text: Without color correction gels, a scene may have a mix of various colors.  Applying color correction gels in front of light sources can alter the color of the various light sources to match.  Mixed lighting can produce an undesirable aesthetic when displayed on a television or in a theatre.

text: China will ban imports and sales of certain incandescent light bulbs starting October 2012 to encourage the use of alternative lighting sources such as light-emitting diodes (LEDs), with a 5-year plan of phasing-out incandescent light bulbs over 100 watts starting 1 October 2012, and gradually extend the ban to those over 15 watts on 1 October 2016.Another source, however, has indicated that by 1 October 2016, all incandescent light bulbs will be banned.According to this source, 1 November 2011 to 30 September 2012 will be a transitional period and as of 1 October 2012, imports and sales of ordinary incandescent bulbs of 100 watts or more will be prohibited. The first phase will be followed by a ban on 60-watt-and-higher incandescent light bulbs starting in October 2014. By October 2016, all incandescent light bulbs will be banned in China.The final phase may be adjusted according to the results of interim assessment from October 2015 to October 2016.

text: China will ban imports and sales of certain incandescent light bulbs starting October 2012 to encourage the use of alternative lighting sources such as

entity_name: Light-emitting diode

text: light-emitting diode

text: s (LEDs), with a 5-year plan of phasing-out incandescent light bulbs over 100 watts starting 1 October 2012, and gradually extend the ban to those over 15 watts on 1 October 2016.Another source, however, has indicated that by 1 October 2016, all incandescent light bulbs will be banned.According to this source, 1 November 2011 to 30 September 2012 will be a transitional period and as of 1 October 2012, imports and sales of ordinary incandescent bulbs of 100 watts or more will be prohibited. The first phase will be followed by a ban on 60-watt-and-higher incandescent light bulbs starting in October 2014. By October 2016, all incandescent light bulbs will be banned in China.The final phase may be adjusted according to the results of interim assessment from October 2015 to October 2016.

method: UNH-qee

text: Before the development of the safety lamp for use in coal mines, dried fish skins were used in Britain and Europe as a weak source of light. This experimental form of illumination avoided the necessity of using candles which risked sparking explosions of firedamp. Another safe source of illumination in mines was bottles containing fireflies. In 1920, the American zoologist E. Newton Harvey published a monograph, The Nature of Animal Light, summarizing early work on bioluminescence. Harvey notes that Aristotle mentions light produced by dead fish and flesh, and that both Aristotle and Pliny the Elder (in his Natural History) mention light from damp wood. He also records that Robert Boyle experimented on these light sources, and showed that both they and the glow-worm require air for light to be produced. Harvey notes that in 1753, J. Baker identified the flagellate Noctiluca "as a luminous animal" "just visible to the naked eye", and in 1854 Johann Florian Heller (1813-1871) identified strands (hyphae) of fungi as the source of light in dead wood.

text: Before the development of the

entity_name: Safety lamp

text: safety lamp

text: for use in coal mines, dried fish skins were used in Britain and Europe as a weak source of light. This experimental form of illumination avoided the necessity of using candles which risked sparking explosions of

entity_name: Firedamp

text: firedamp

text: . Another safe source of illumination in mines was bottles containing fireflies. In 1920, the American zoologist

entity_name: E. Newton Harvey

text: E. Newton Harvey

text: published a monograph, The Nature of Animal Light, summarizing early work on bioluminescence. Harvey notes that

entity_name: Aristotle

text: Aristotle

text: mentions light produced by dead fish and flesh, and that both Aristotle and

entity_name: Pliny the Elder

text: Pliny the Elder

text: (in his

entity_name: Natural History (Pliny)

text: Natural History

text: ) mention light from damp wood. He also records that

entity_name: Robert Boyle

text: Robert Boyle

text: experimented on these light sources, and showed that both they and the glow-worm require air for light to be produced. Harvey notes that in 1753, J. Baker identified the flagellate Noctiluca "as a luminous animal" "just visible to the naked eye", and in 1854

entity_name: Johann Florian Heller

text: Johann Florian Heller

text: (1813-1871) identified strands (

entity_name: Hypha

text: hypha

text: e) of fungi as the source of light in dead wood.

text: Brand new high-intensity discharge lamps make more visible light per unit of electric power consumed than fluorescent and incandescent lamps, since a greater proportion of their radiation is visible light in contrast to infrared. However, the lumen output of HID lighting can deteriorate by up to 70% over 10,000 burning hours.

text: Brand new high-intensity discharge lamps make more

entity_name: Luminous efficacy

text: visible light per unit of electric power consumed

text: than

entity_name: Fluorescent lamp

text: fluorescent

text: and

entity_name: Incandescent light bulb

text: incandescent

text: lamps, since a greater proportion of their radiation is visible light in contrast to infrared. However, the lumen output of HID lighting can deteriorate by up to 70% over 10,000 burning hours.

text: Pigments appear the colors they are because they selectively reflect and absorb certain wavelengths of visible light. White light is a roughly equal mixture of the entire spectrum of visible light with a wavelength in a range from about 375 or 400 nanometers to about 760 or 780 nm. When this light encounters a pigment, parts of the spectrum are absorbed by the molecules or ions of the pigment. In organic pigments such as diazo or phthalocyanine compounds the light is absorbed by the conjugated systems of double bonds in the molecule. Some of the inorganic pigments such as vermilion (mercury sulfide) or cadmium yellow (cadmium sulfide) absorb light by transferring an electron from the negative ion (S) to the positive ion (Hg or Cd). Such compounds are designated as charge-transfer complexes, with broad absorption bands that subtract most of the colors of the incident white light. The other wavelengths or parts of the spectrum are reflected or scattered. The new reflected light spectrum creates the appearance of a color. Pigments, unlike fluorescent or phosphorescent substances, can only subtract wavelengths from the source light, never add new ones.

text: Pigments appear the colors they are because they selectively reflect and absorb certain wavelengths of

entity_name: Light

text: visible light

entity_name: White

text: White light

text: is a roughly equal mixture of the entire spectrum of visible light with a

entity_name: Wavelength

text: wavelength

text: in a range from about 375 or 400

entity_name: Nanometre

text: nanometer

text: s to about 760 or 780 nm. When this light encounters a pigment, parts of the spectrum are

entity_name: Absorption (electromagnetic radiation)

text: absorbed

text: by the molecules or ions of the pigment. In organic pigments such as

entity_name: Azo compound

text: diazo

text: or

entity_name: Phthalocyanine

text: phthalocyanine

text: compounds the light is absorbed by the

entity_name: Conjugated system

entity_section: Conjugated systems in pigments

text: conjugated systems

text: of

entity_name: Double bond

text: double bond

text: s in the molecule. Some of the inorganic pigments such as

entity_name: Vermilion

text: vermilion

text: (mercury sulfide) or

entity_name: Cadmium pigments

text: cadmium yellow

text: (cadmium sulfide) absorb light by transferring an electron from the negative ion (S) to the positive ion (Hg or Cd). Such compounds are designated as

entity_name: Charge-transfer complex

text: charge-transfer complex

text: es, with broad

entity_name: Absorption band

text: absorption band

text: s that subtract most of the colors of the incident white light. The other wavelengths or parts of the spectrum are reflected or scattered. The new reflected light spectrum creates the appearance of a

entity_name: Color

text: color

text: . Pigments, unlike

entity_name: Fluorescence

text: fluorescent

text: or

entity_name: Phosphorescence

text: phosphorescent

text: substances, can only

entity_name: Subtractive color

text: subtract

text: wavelengths from the source light, never add new ones.

text: The first prototype Beckman spectrophotometer, the Model A, was created at National Technologies Laboratories in 1940.  It used a tungsten light source with a glass Fery prism  as a monochromator. Tungsten was used for incandescent light filaments because it was strong, withstood heat, and emitted a steady light. Types of light sources differed in the range of wavelengths of light that they emitted.  Tungsten lamps were useful in the visible light range but gave poor coverage in the ultraviolet range. However, they had the advantage of being readily available because they were used as automobile headlamps. An external amplifier from the Beckman pH meter and a vacuum tube photocell were used to detect wavelengths.

text: The first prototype Beckman spectrophotometer, the Model A, was created at National Technologies Laboratories in 1940.  It used a

entity_name: Tungsten

text: tungsten

text: light source with a glass

text: Fery prism

text: as a

entity_name: Monochromator

text: monochromator

text: . Tungsten was used for

text: incandescent light

text: filaments because it was strong, withstood heat, and emitted a steady light. Types of light sources differed in the range of wavelengths of light that they emitted.  Tungsten lamps were useful in the visible light range but gave poor coverage in the ultraviolet range. However, they had the advantage of being readily available because they were used as automobile

entity_name: Headlamp

text: headlamps

text: . An external amplifier from the Beckman pH meter and a

entity_name: Vacuum tube

text: vacuum tube

text: photocell were used to detect wavelengths.

text: Luminous efficacy is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power, measured in lumens per watt in SI. Depending on context, the power can be either the radiant flux of the source's output, or it can be the total power (electric power, chemical energy, or others) consumed by the source.Which sense of the term is intended must usually be inferred from the context, and is sometimes unclear. The former sense is sometimes called luminous efficacy of radiation, and the latter luminous efficacy of a source or overall luminous efficacy.

text: Luminous efficacy is a measure of how well a light source produces visible light. It is the ratio of

entity_name: Luminous flux

text: luminous flux

text: to

entity_name: Power (physics)

text: power

text: , measured in

entity_name: Lumen (unit)

text: lumens

text: per

entity_name: Watt

text: watt

text: in

entity_name: International System of Units

text: SI

text: . Depending on context, the power can be either the

entity_name: Radiant flux

text: radiant flux

text: of the source's output, or it can be the total power (electric power, chemical energy, or others) consumed by the source.Which sense of the term is intended must usually be inferred from the context, and is sometimes unclear. The former sense is sometimes called luminous efficacy of radiation, and the latter luminous efficacy of a source or overall luminous efficacy.

method: UvABottomUpChangeOrder

text: Visible light can be seen by the naked eye (and thus forms images that people can look at), but it does not penetrate most objects (only translucent ones). In contrast, X-rays can penetrate a wider variety of objects (such as the human body), but they are invisible to the naked eye. To take advantage of the penetration for image-forming purposes, one must somehow convert the X-rays' intensity variations (which correspond to material contrast and thus image contrast) into a form that is visible. Classic film-based radiography achieves this by the variable chemical changes that the X-rays induce in the film, and classic fluoroscopy achieves it by fluorescence, in which certain materials convert X-ray energy (or other parts of the spectrum) into visible light. This use of fluorescent materials to make a viewing scope is how fluoroscopy got its name.

text: Visible light

text: can be seen by the naked eye (and thus forms images that people can look at), but it does not penetrate most objects (only

entity_name: Transparency and translucency

text: translucent

text: ones). In contrast, X-rays can penetrate a wider variety of objects (such as the human body), but they are invisible to the naked eye. To take advantage of the penetration for image-forming purposes, one must somehow convert the X-rays'

entity_name: Intensity (physics)

text: intensity

text: variations (which correspond to material contrast and thus image contrast) into a form that is visible. Classic film-based radiography achieves this by the variable chemical changes that the X-rays induce in the

entity_name: Photographic film

text: film

text: , and classic fluoroscopy achieves it by

text: fluorescence

text: , in which certain materials convert X-ray energy (or other parts of the

entity_name: Electromagnetic spectrum

text: spectrum

text: ) into visible light. This use of fluorescent materials to make a

text: viewing scope

text: is how fluoroscopy got its name.

text: Global illumination (shortened as GI), or indirect illumination, is a general name for a group of algorithms used in 3D computer graphics that are meant to add more realistic lighting to 3D scenes. Such algorithms take into account not only the light that comes directly from a light source (direct illumination), but also subsequent cases in which light rays from the same source are reflected by other surfaces in the scene, whether reflective or not (indirect illumination).

text: Global illumination (shortened as GI), or indirect illumination, is a general name for a group of

entity_name: Algorithm

text: algorithm

text: s used in

entity_name: 3D computer graphics

text: 3D computer graphics

text: that are meant to add more realistic lighting to 3D scenes. Such algorithms take into account not only the light that comes directly from a light source (direct illumination), but also subsequent cases in which light rays from the same source are reflected by other surfaces in the scene, whether reflective or not (indirect illumination).

text: The brain, being the source of perception, voluntary movement, and free will, is also described as the source of psychic pneuma. Starting out from the heart as vital pneuma, it moves towards the brain where it is further refined into the specialized pneuma to be employed for vision. Hunayn also introduces the concept of a sense hierarchy, placing sight at the top of the list with the corresponding element of fire. In addition, he also describes three levels of this element: flame, red heat, and light, rationalizing the inclusion of light by describing the creation of flames after concentrating it via a magnetic glass. Hunayn connects all of these ideas by referencing the fact that the brain works directly to provide the eyes with the pneuma necessary to carry out its function, with light providing the illumination needed to discern the object being viewed.

text: The brain, being the source of

entity_name: Perception

text: perception

text: , voluntary movement, and

entity_name: Free will

text: free will

text: , is also described as the source of psychic pneuma. Starting out from the

entity_name: Heart

text: heart

text: as vital pneuma, it moves towards the brain where it is further refined into the specialized pneuma to be employed for vision. Hunayn also introduces the concept of a sense hierarchy, placing sight at the top of the list with the corresponding element of fire. In addition, he also describes three levels of this element: flame, red heat, and light, rationalizing the inclusion of light by describing the creation of flames after concentrating it via a magnetic glass. Hunayn connects all of these ideas by referencing the fact that the brain works directly to provide the eyes with the pneuma necessary to carry out its function, with light providing the illumination needed to discern the object being viewed.

text: The tower original light source was a 55-millimetre (2.2 in) vapourised kerosene incandescent mantle, with an intensity of 150,000 cd and a visible range of . The original lens was a Chance Brothers 3rd order 500-millimetre (20 in) dioptric fresnel lens. The apparatus was a rotating pedestal floating in a mercury bath, operated by a clockwork mechanism with descending weights, which only had to be rewound once every twelve hours.

text: The tower original light source was a 55-millimetre (2.2 in) vapourised

entity_name: Kerosene

text: kerosene

text: incandescent mantle, with an intensity of 150,000

entity_name: Candela

text: cd

text: and a visible range of . The original lens was a

entity_name: Chance Brothers

text: Chance Brothers

text: 3rd order 500-millimetre (20 in)

entity_name: Dioptrics

text: dioptric

entity_name: Fresnel lens

text: fresnel lens

text: . The apparatus was a rotating pedestal floating in a mercury bath, operated by a

entity_name: Clockwork

text: clockwork

text: mechanism with descending weights, which only had to be rewound once every twelve hours.

text: The UV light is absorbed by the lamp's fluorescent coating, which re-radiates the energy at longer wavelengths to emit visible light. Not all the UV energy striking the phosphor gets converted into visible light. In a modern lamp, for every 100 incident photons of UV impacting the phosphor, only 86 visible light photons are emitted (a quantum efficiency of 86%). The largest single loss in modern lamps is due to the lower energy of each photon of visible light, compared to the energy of the UV photons that generated them (a phenomenon called Stokes shift). Incident photons have an energy of 5.5 electron volts but produce visible light photons with energy around 2.5 electron volts, so only 45% of the UV energy is used; the rest is dissipated as heat. If a so-called "two-photon" phosphor could be developed, this would improve the efficiency but much research has not yet found such a system.

text: The UV light is

text: absorbed

text: by the lamp's

text: fluorescent

text: coating, which re-radiates the energy at longer wavelengths to emit

text: visible light

text: . Not all the UV energy striking the phosphor gets converted into visible light. In a modern lamp, for every 100 incident photons of UV impacting the phosphor, only 86 visible light photons are emitted (a quantum efficiency of 86%). The largest single loss in modern lamps is due to the lower energy of each photon of visible light, compared to the energy of the UV photons that generated them (a phenomenon called

entity_name: Stokes shift

text: Stokes shift

text: ). Incident photons have an energy of 5.5 electron volts but produce visible light photons with energy around 2.5 electron volts, so only 45% of the UV energy is used; the rest is dissipated as heat. If a so-called "two-photon" phosphor could be developed, this would improve the efficiency but much research has not yet found such a system.

text: Köhler illumination is a method of specimen illumination used for transmitted and reflected light (trans- and epi-illuminated) optical microscopy. Köhler illumination acts to generate an extremely even illumination of the sample and ensures that an image of the illumination source (for example a halogen lamp filament) is not visible in the resulting image. Köhler illumination is the predominant technique for sample illumination in modern scientific light microscopy. It requires additional optical elements which are more expensive and may not be present in more basic light microscopes.

text: Köhler illumination is a method of

entity_name: Laboratory specimen

text: specimen

entity_name: Lighting

text: illumination

text: used for transmitted and reflected light (trans- and epi-illuminated)

entity_name: Optical microscope

text: optical

entity_name: Microscopy

text: microscopy

text: . Köhler illumination acts to generate an extremely even illumination of the sample and ensures that an image of the illumination source (for example a

entity_name: Halogen lamp

text: halogen lamp

entity_section: Filament

text: filament

text: ) is not visible in the resulting

entity_name: Image

text: image

text: . Köhler illumination is the predominant technique for sample illumination in modern scientific light microscopy. It requires additional optical elements which are more expensive and may not be present in more basic light microscopes.

text: In photometry, luminous energy is the perceived energy of light. This is sometimes called the quantity of light. Luminous energy is not the same as radiant energy, the corresponding objective physical quantity. This is because the human eye can only see light in the visible spectrum and has different sensitivities to light of different wavelengths within the spectrum. When adapted for bright conditions (photopic vision), the eye is most sensitive to light at a wavelength of 555 nm. Light with a given amount of radiant energy will have more luminous energy if the wavelength is 555 nm than if the wavelength is longer or shorter. Light whose wavelength is well outside the visible spectrum has a luminous energy of zero, regardless of the amount of radiant energy present.

text: In

entity_name: Photometry (optics)

text: photometry

text: , luminous energy is the perceived

entity_name: Energy

text: energy

text: of

text: light

text: . This is sometimes called the quantity of light. Luminous energy is not the same as

entity_name: Radiant energy

text: radiant energy

text: , the corresponding objective

entity_name: Physical quantity

text: physical quantity

text: . This is because the

entity_name: Human eye

text: human eye

text: can only see light in the

text: visible spectrum

text: and has different sensitivities to

text: light

text: of different

text: wavelength

text: s within the spectrum. When adapted for bright conditions (

text: photopic vision

text: ), the eye is most sensitive to light at a wavelength of 555

text: nm

text: . Light with a given amount of radiant energy will have more luminous energy if the wavelength is 555 nm than if the wavelength is longer or shorter. Light whose wavelength is well outside the

text: visible spectrum

text: has a luminous energy of zero, regardless of the amount of radiant energy present.

text: Keyboards and keypads may be illuminated from inside, especially on equipment for mobile use. Illumination facilitates the use of the keyboard or keypad in dark environments. Some gaming keyboards have lighted keys, to make it easier for gamers to find command keys while playing in a dark room. Some keyboards may have small LED lights in a few important function keys, to remind users that the function is activated (see photo).

text: Luminescence became Anggun's comeback album in France, selling over 121,000 copies there. In Indonesia, the album was certified quadruple platinum for exceeding sales of over 450,000 copies as of 2015. With the album, Anggun expanded her popularity to Eastern Europe. Luminescence was certified gold in Russia, while the album's singles accumulatively received more than 79,000 plays on Russian radio according to TopHit.ru. Luminescence received Platinum Export Award for its sales outside France. The album spawned singles "Être une femme", "Cesse la pluie", "Juste avant toi" and "Garde-moi" (featuring David Hallyday) from the French version, as well as "Undress Me", "In Your Mind", "Saviour", "I'll Be Alright" and "A Crime" from the English version.

text: Luminescence became Anggun's comeback album in France, selling over 121,000 copies there. In Indonesia, the album was certified quadruple platinum for exceeding sales of over 450,000 copies as of 2015. With the album, Anggun expanded her popularity to

text: Eastern Europe

text: . Luminescence was certified gold in Russia, while the album's singles accumulatively received more than 79,000 plays on Russian radio according to

text: TopHit.ru

text: . Luminescence received Platinum Export Award for its sales outside France. The album spawned singles "

text: Être une femme

text: Cesse la pluie

text: Juste avant toi

text: " and "Garde-moi" (featuring

text: David Hallyday

text: ) from the French version, as well as "Undress Me", "

text: In Your Mind

text: Saviour

text: I'll Be Alright

text: " and "A Crime" from the English version.

text: Reflectors can also be used to selectively reduce or eliminate unwanted thermal emission. Incandescent lamps produce light through heating of the filament, while arc lamps produce light through the heating and ionization of a gas. In either case, this heat is also emitted from the lamp as infrared light. The thermal energy is often projected onto the stage with the visible light, and thousands of watts of incandescent lighting can be uncomfortably hot for the actors on stage. Specially designed reflectors are able to absorb and dissipate infrared at the fixture before the visible light reaches the stage.

text: The amount of luminescence is proportional to the original dose of radiation received. In thermoluminescence dating, this can be used to date buried objects that have been heated in the past, since the ionizing dose received from radioactive elements in the soil or from cosmic rays is proportional to age.  This phenomenon has been applied in the thermoluminescent dosimeter, a device to measure the radiation dose received by a chip of suitable material that is carried by a person or placed with an object.

text: The amount of luminescence is proportional to the original dose of radiation received. In

text: thermoluminescence dating

text: , this can be used to date buried objects that have been heated in the past, since the ionizing dose received from

text: radioactive

text: elements in the soil or from

text: cosmic ray

text: s is proportional to age.  This phenomenon has been applied in the

text: thermoluminescent dosimeter

text: , a device to measure the radiation dose received by a chip of suitable material that is carried by a person or placed with an object.

text: Flare is the diffraction of light in the human lens, resulting in "rays" of light emanating from small light sources, and can also result in some chromatic effects.  It is most visible on point light sources because of their small visual angle.

text: It was discovered by three teams in September 2009 in sensitive infrared Hubble Space Telescope images and identified by these as source UDF-38135539 (R Bouwens et al.,) source HUDF.YD3 (A Bunker et al.) and source 1721 (R McLure et al.), and additionally reported in the Astrophysical Journal, and the Monthly Notices of the Royal Astronomical Society. All teams independently identified the source likely  an extremely distant galaxy because there were no measurable light at visible wavelengths (caused by absorption of hydrogen gas along the line of sight). Following the discovery of this candidate distant galaxy, another team targeted this object with ground-based spectroscopy to confirm the distance, reporting a redshift z=8.6.However, attempts to replicate this observation strongly suggest the original claim was in error, meaning that at the present time the galaxy only has a photometric redshift estimate.

text: It was discovered by three teams in September 2009 in sensitive infrared

text: Hubble Space Telescope

text: images and identified by these as source UDF-38135539 (

text: R Bouwens

text: et al.,) source HUDF.YD3 (A Bunker et al.) and source 1721 (R McLure et al.), and additionally reported in the Astrophysical Journal, and the Monthly Notices of the Royal Astronomical Society. All teams independently identified the source likely  an extremely distant galaxy because there were no measurable light at

text: visible wavelengths

text: (caused by absorption of

text: hydrogen gas

text: along the line of sight). Following the discovery of this candidate distant galaxy, another team targeted this object with ground-based

text: spectroscopy

text: to confirm the distance, reporting a

text: redshift

text: z=8.6.However, attempts to replicate this observation strongly suggest the original claim was in error, meaning that at the present time the galaxy only has a photometric redshift estimate.

text: The photometry units are different from most systems of physical units in that they take into account how the human eye responds to light. The cone cells in the human eye are of three types which respond differently across the visible spectrum, and the cumulative response peaks at a wavelength of around 555 nm. Therefore, two sources of light which produce the same intensity (W/m) of visible light do not necessarily appear equally bright. The photometry units are designed to take this into account, and therefore are a better representation of how "bright" a light appears to be than raw intensity. They relate to raw power by a quantity called luminous efficacy, and are used for purposes like determining how to best achieve sufficient illumination for various tasks in indoor and outdoor settings. The illumination measured by a photocell sensor does not necessarily correspond to what is perceived by the human eye, and without filters which may be costly, photocells and charge-coupled devices (CCD) tend to respond to some infrared, ultraviolet or both.

text: The photometry units are different from most systems of physical units in that they take into account how the human eye responds to light. The

text: cone cell

text: s in the human eye are of three types which respond differently across the visible spectrum, and the cumulative response peaks at a wavelength of around 555 nm. Therefore, two sources of light which produce the same intensity (W/m) of visible light do not necessarily appear equally bright. The photometry units are designed to take this into account, and therefore are a better representation of how "bright" a light appears to be than raw intensity. They relate to raw

text: power

text: by a quantity called

text: luminous efficacy

text: , and are used for purposes like determining how to best achieve sufficient illumination for various tasks in indoor and outdoor settings. The illumination measured by a

text: photocell

text: sensor does not necessarily correspond to what is perceived by the human eye, and without filters which may be costly, photocells and

text: charge-coupled device

text: s (CCD) tend to respond to some

text: infrared

text: ultraviolet

text: or both.

text: Socrates' argument is that in the ideal city, a true philosopher with understanding of forms will facilitate the harmonious co-operation of all the citizens of the city. This philosopher-king must be intelligent, reliable, and willing to lead a simple life. However, these qualities are rarely manifested on their own, and so they must be encouraged through education and the study of Good. Just as visible objects must be illuminated in order to be seen, so must also be true of objects of knowledge if light is cast on them. Just as light comes from the Sun, so does truth come from goodness. Goodness as the source of truth makes it possible for the mind to know, just as light from the Sun makes the eyes able to see.

text: The Ohio Statehouse has been termed a supreme example of Greek Revival style. It is not patterned on one single building, but is a combination of stylistic elements from Greek sources, melded with contemporary needs and functions. The cupola shows direct influence by the Tholos of Delphi, a circular temple built about 360 BC. The Parthenon of Athens is also an influence. No ancient Greek building would have contained windows, but they were a major part of Greek Revival for a more practical reason: before electric light, sunlight was the major source of illumination.

text: The Ohio Statehouse has been termed a supreme example of Greek Revival style. It is not patterned on one single building, but is a combination of stylistic elements from Greek sources, melded with contemporary needs and functions. The cupola shows direct influence by the Tholos of Delphi, a circular temple built about 360 BC. The

text: Parthenon

text: of Athens is also an influence. No ancient Greek building would have contained windows, but they were a major part of Greek Revival for a more practical reason: before electric light, sunlight was the major source of illumination.

text: The optical properties of the lining of the sphere greatly affect its accuracy. Different coatings must be used at visible, infrared and ultraviolet wavelengths. High-powered illumination sources may heat or damage the coating, so an integrating sphere will be rated for a maximum level of incident power. Various coating materials are used.  For visible-spectrum light, early experimenters used a deposit of magnesium oxide,  and barium sulfate also has a usefully flat reflectance over the visible spectrum. Various proprietary PTFE compounds are also used for visible light measurements. Finely-deposited gold is used for infrared measurements.

text: The optical properties of the lining of the sphere greatly affect its accuracy. Different coatings must be used at visible, infrared and ultraviolet wavelengths. High-powered illumination sources may heat or damage the coating, so an integrating sphere will be rated for a maximum level of incident power. Various coating materials are used.  For visible-spectrum light, early experimenters used a deposit of

text: magnesium oxide

text: ,  and

text: barium sulfate

text: also has a usefully flat reflectance over the visible spectrum. Various proprietary

text: PTFE

text: compounds are also used for visible light measurements. Finely-deposited gold is used for infrared measurements.

text: The fluorescent type of luminescence is significantly different from the natural bio-luminescence of bacteria, insects and fish such as the case of the firefly, etc. Bio-luminescence involves no reflection at all, but living generation of light (via the chemistry of Luciferin).

text: The fluorescent type of luminescence is significantly different from the natural

text: bio-luminescence

text: of bacteria, insects and fish such as the case of the firefly, etc. Bio-luminescence involves no reflection at all, but living generation of light (via the chemistry of

text: Luciferin

text: In translumination, the spectrum of white light is divided into different wavelengths (colors). A histogram represents the graphic visualization of these colors and the luminescence of the obtained images. In a histogram, the intensity of the luminescence is accompanied by a gray baseline that decreases as the source approaches, where the red scale is more intense and is represented by a line in ascension. The scales of blue and green colors represent the refraction indexes of the light emitted by the transluminator in contact with the studied area. In the histogram when the selection of a scale (for example, the green scale) is disabled, the luminescence intensity of captured images may be mapped. Bollinger et al. reported their experience: denominated fluorescence videomiscroscopy, based on the video capture of images and study of their luminescence through light emission stimulated by 20% sodium-fluorocein (0.3 ml/l of blood). The principles of spectrographic analysis of this test are similar to those used to evaluate the luminescence of captured images by venous translumination, and the histogram also evaluates the scales of red, blue and green (RGB). All organic components are composed of chemical elements that emit light according to their wavelength. This is why the histogram analysis of transluminated images could define an organic element according to the quality and amount of their components.

text: In translumination, the spectrum of white light is divided into different wavelengths (colors). A histogram represents the graphic visualization of these colors and the luminescence of the obtained images. In a

text: histogram

text: , the intensity of the luminescence is accompanied by a gray baseline that decreases as the source approaches, where the red scale is more intense and is represented by a line in ascension. The scales of blue and green colors represent the refraction indexes of the light emitted by the transluminator in contact with the studied area. In the histogram when the selection of a scale (for example, the green scale) is disabled, the

text: luminescence

text: intensity of captured images may be mapped. Bollinger et al. reported their experience: denominated

text: fluorescence

text: videomiscroscopy, based on the video capture of images and study of their luminescence through light emission stimulated by 20% sodium-fluorocein (0.3 ml/l of blood). The principles of spectrographic analysis of this test are similar to those used to evaluate the luminescence of captured images by venous translumination, and the histogram also evaluates the scales of red, blue and green (RGB). All organic components are composed of chemical elements that emit light according to their wavelength. This is why the histogram analysis of transluminated images could define an organic element according to the quality and amount of their components.

text: A compact fluorescent lamp is a fluorescent lamp designed to replace an incandescent lightbulb. Some CFL's fit into light fixtures formerly used for incandescent lamps and they are designed to produce the same amount of visible light found in incandescent light. CFLs generally use 70% less energy and have a longer rated life. In 1941, George Inman devised the first practical fluorescent lamp while working for General Electric. The key patent for this light source, U.S. patent #2,259,040 was filed by Inman on April 22, 1936 and issued to him on October 14, 1941. In 1976, Edward E. Hammer invented the first helical or spiraled compact fluorescent lamp, but due to the difficulty of the manufacturing process for coating the interior of the spiral glass tube, General Electric did not manufacture or sell the device. Other companies began manufacturing and selling the device in 1995.

text: A compact fluorescent lamp is a

text: fluorescent

text: lamp designed to replace an

text: incandescent lightbulb

text: . Some CFL's fit into light fixtures formerly used for incandescent lamps and they are designed to produce the same amount of visible light found in incandescent light. CFLs generally use 70% less energy and have a longer rated life. In 1941, George Inman devised the first practical fluorescent lamp while working for

text: General Electric

text: . The key patent for this light source, U.S. patent #2,259,040 was filed by Inman on April 22, 1936 and issued to him on October 14, 1941. In 1976,

text: Edward E. Hammer

text: invented the first

text: helical

text: or spiraled compact fluorescent lamp, but due to the difficulty of the manufacturing process for coating the interior of the spiral glass tube, General Electric did not manufacture or sell the device. Other companies began manufacturing and selling the device in 1995.

text: Dating of these abandoned terrace surfaces (treads) is possible using a variety of geochronologic techniques.  The type of technique used, however, is dependent on the composition and age of the terraces.  Currently used techniques are magnetostratigraphy, low temperature thermochronology, cosmogenic nuclides, radiocarbon, thermoluminescence, optically stimulated luminescence, and U-Th disequilibria. Additionally, if there is a succession of preserved fossils, biostratigraphy can be used.

text: Dating of these abandoned terrace surfaces (treads) is possible using a variety of

text: geochronologic

text: techniques.  The type of technique used, however, is dependent on the composition and age of the terraces.  Currently used techniques are

text: magnetostratigraphy

text: , low temperature

text: thermochronology

text: cosmogenic nuclide

text: s,

text: radiocarbon

text: thermoluminescence

text: optically stimulated luminescence

text: , and

text: U-Th disequilibria

text: . Additionally, if there is a succession of preserved fossils,

text: biostratigraphy

text: can be used.

text: An electromagnetic field very far from currents and charges (sources) is called electromagnetic radiation (EMR) since it radiates from the charges and currents in the source, and has no "feedback" effect on them, and is also not affected directly by them in the present time (rather, it is indirectly produced by a sequences of changes in fields radiating out from them in the past). EMR consists of the radiations in the electromagnetic spectrum, including radio waves, microwave, infrared, visible light, ultraviolet light, X-rays, and gamma rays. The many commercial applications of these radiations are discussed in the named and linked articles.

text: An electromagnetic field very far from currents and charges (sources) is called

text: electromagnetic radiation

text: (EMR) since it radiates from the charges and currents in the source, and has no "feedback" effect on them, and is also not affected directly by them in the present time (rather, it is indirectly produced by a sequences of changes in fields radiating out from them in the past). EMR consists of the radiations in the

text: electromagnetic spectrum

text: , including

text: radio wave

text: s,

text: microwave

text: infrared

text: visible light

text: ultraviolet light

text: X-rays

text: , and

text: gamma ray

text: s. The many commercial applications of these radiations are discussed in the named and linked articles.

text: In the Crab Nebula X-ray spectrum there are three features that differ greatly from Scorpius X-1: its spectrum is much harder, its source diameter is in light-years (ly)s, not astronomical units (AU), and its radio and optical synchrotron emission are strong. Its overall X-ray luminosity rivals the optical emission and could be that of a nonthermal plasma. However, the Crab Nebula appears as an X-ray source that is a central freely expanding ball of dilute plasma, where the energy content is 100 times the total energy content of the large visible and radio portion, obtained from the unknown source.

text: In the Crab Nebula X-ray spectrum there are three features that differ greatly from Scorpius X-1: its spectrum is much harder, its source diameter is in

text: light-year

text: s (ly)s, not

text: astronomical unit

text: s (AU), and its radio and optical synchrotron emission are strong. Its overall X-ray luminosity rivals the optical emission and could be that of a nonthermal plasma. However, the Crab Nebula appears as an X-ray source that is a central freely expanding ball of dilute plasma, where the energy content is 100 times the total energy content of the large visible and radio portion, obtained from the unknown source.

text: Luminescence is the result of a chemical or biochemical reaction. Luminescence detection is simpler optically than fluorescence detection because luminescence does not require a light source for excitation or optics for selecting discrete excitation wavelengths. A typical luminescence optical system consists of a light-tight reading chamber and a PMT detector. Some plate readers use an Analog PMT detector while others have a photon counting PMT detector. Photon Counting is widely accepted as the most sensitive means of detecting luminescence. Some plate readers offer filter wheel or tunable wavelength monochromator optical systems for selecting specific luminescent wavelengths.  The ability to select multiple wavelengths, or even wavelength ranges, allows for detection of assays that contain multiple luminescent reporter enzymes, the development of new luminescence assays, as well as a means to optimize signal to noise.

text: Luminescence is the result of a chemical or biochemical reaction. Luminescence detection is simpler optically than fluorescence detection because luminescence does not require a light source for excitation or optics for selecting discrete excitation wavelengths. A typical luminescence optical system consists of a light-tight reading chamber and a

text: PMT

text: detector. Some plate readers use an Analog PMT detector while others have a

text: photon counting

text: PMT detector. Photon Counting is widely accepted as the most sensitive means of detecting luminescence. Some plate readers offer filter wheel or tunable wavelength monochromator optical systems for selecting specific luminescent wavelengths.  The ability to select multiple wavelengths, or even wavelength ranges, allows for detection of assays that contain multiple luminescent reporter enzymes, the development of new luminescence assays, as well as a means to optimize signal to noise.

text: Many species can see light with frequencies outside the human "visible spectrum". Bees and many other insects can detect ultraviolet light, which helps them to find nectar in flowers. Plant species that depend on insect pollination may owe reproductive success to ultraviolet "colors" and patterns rather than how colorful they appear to humans. Birds, too, can see into the ultraviolet (300–400 nm), and some have sex-dependent markings on their plumage that are visible only in the ultraviolet range. Many animals that can see into the ultraviolet range, however, cannot see red light or any other reddish wavelengths.  For example, bees' visible spectrum ends at about 590 nm, just before the orange wavelengths start. Birds, however, can see some red wavelengths, although not as far into the light spectrum as humans. It is an incorrect popular belief that the common goldfish is the only animal that can see both infrared and ultraviolet light, their color vision extends into the ultraviolet but not the infrared.

text: Many species can see light with frequencies outside the human "visible spectrum".

text: Bee

text: s and many other insects can detect ultraviolet light, which helps them to find

text: nectar

text: in flowers. Plant species that depend on insect pollination may owe reproductive success to ultraviolet "colors" and patterns rather than how colorful they appear to humans. Birds, too, can see into the ultraviolet (300–400 nm), and some have sex-dependent markings on their plumage that are visible only in the ultraviolet range. Many animals that can see into the ultraviolet range, however, cannot see red light or any other reddish wavelengths.  For example, bees' visible spectrum ends at about 590 nm, just before the orange wavelengths start. Birds, however, can see some red wavelengths, although not as far into the light spectrum as humans. It is an incorrect popular belief that the common goldfish is the only animal that can see both infrared and ultraviolet light, their color vision extends into the ultraviolet but not the infrared.

text: The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of comparable hue to that of the light source. Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, horticulture, and other fields. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e., those on a line from reddish/orange via yellow and more or less white to blueish white; it does not make sense to speak of the color temperature of, e.g., a green or a purple light. Color temperature is conventionally expressed in kelvins, using the symbol K, a unit of measure for temperature based on the Kelvin scale.

text: The color temperature of a light source is the

text: temperature

text: of an ideal

text: black-body radiator

text: that radiates light of comparable

text: hue

text: to that of the light source. Color temperature is a characteristic of

text: visible light

text: that has important applications in

text: lighting

text: photography

text: videography

text: publishing

text: manufacturing

text: astrophysics

text: horticulture

text: , and other fields. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e., those on a line from reddish/orange via yellow and more or less white to blueish white; it does not make sense to speak of the color temperature of, e.g., a green or a purple light. Color temperature is conventionally expressed in

text: kelvins

text: , using the symbol K, a

text: unit of measure

text: for temperature based on the Kelvin scale.

text: A heat lamp is an incandescent light bulb that is used for the principal purpose of creating heat. The spectrum of black body radiation emitted by the lamp is shifted to produce more infrared light. Many heat lamps include a red filter to minimize the amount of visible light emitted. Heat lamps often include an internal reflector.

text: A

text: heat lamp

text: is an

text: incandescent light bulb

text: that is used for the principal purpose of creating heat. The spectrum of

text: black body radiation

text: emitted by the lamp is shifted to produce more

text: infrared light

text: . Many heat lamps include a red filter to minimize the amount of visible light emitted. Heat lamps often include an internal reflector.

text: The following are types of luminescence:

text: Infrared light lies between the visible and microwave portions of the electromagnetic spectrum. Infrared light has a range of wavelengths, just like visible light has wavelengths that range from red light to violet. "Near infrared" light is closest in wavelength to visible light and "far infrared" is closer to the microwave region of the electromagnetic spectrum. The longer, far infrared wavelengths are about the size of a pin head and the shorter, near infrared ones are the size of cells, or are microscopic.

text: Infrared light lies between the visible and microwave portions of the

text: electromagnetic spectrum

text: . Infrared light has a range of wavelengths, just like visible light has wavelengths that range from red light to violet. "Near infrared" light is closest in wavelength to visible light and "far infrared" is closer to the microwave region of the electromagnetic spectrum. The longer, far infrared wavelengths are about the size of a pin head and the shorter, near infrared ones are the size of cells, or are microscopic.

text: Key considerations of landing light design include intensity, reliability, weight, and power consumption. Ideal landing lights are extremely intense, require little electrical power, are lightweight, and have long and predictable service lives. Past and present technologies include ordinary incandescent lamps, halogen lamps, various forms of arc lamps and discharge lamps, and LED lamps.

text: Key considerations of landing light design include intensity, reliability, weight, and power consumption. Ideal landing lights are extremely intense, require little electrical power, are lightweight, and have long and predictable service lives. Past and present technologies include ordinary

text: incandescent lamps

text: halogen lamp

text: s, various forms of

text: arc lamp

text: s and

text: discharge lamp

text: s, and

text: LED

text: lamps.

text: Compared with an incandescent lamp, a fluorescent tube is a more diffuse and physically larger light source. In suitably designed lamps, light can be more evenly distributed without point source of glare such as seen from an undiffused incandescent filament; the lamp is large compared to the typical distance between lamp and illuminated surfaces.

text: The PH Artichoke Pendant is a designer Light fixture manufactured by Louis Poulsen. It was designed by Poul Henningsen in 1958. A chrome inner diffuser also assists in the proper even reflection of the light source. The light source can be an incandescent bulb (high powered halogen or xenon), fluorescent (with the ballast mounted in fixture canopy), or metal halide (canopy-mounted ballast). The metal halide sources are used in the largest of the Artichoke fixtures.  For years, a number of companies have tried to replicate the Artichoke fixture; only a handful have made a replica that is at all geometrically and cosmetically similar.

text: The PH Artichoke Pendant is a

text: designer

text: Light fixture

text: manufactured by

text: Louis Poulsen

text: . It was designed by

text: Poul Henningsen

text: in 1958. A chrome inner diffuser also assists in the proper even reflection of the light source. The light source can be an

text: incandescent bulb

text: (high powered

text: halogen

text: or

text: xenon

text: fluorescent

text: (with the ballast mounted in fixture canopy), or

text: metal halide

text: (canopy-mounted ballast). The metal halide sources are used in the largest of the Artichoke fixtures.  For years, a number of companies have tried to replicate the Artichoke fixture; only a handful have made a replica that is at all geometrically and cosmetically similar.

text: Bug zappers are usually housed in a protective cage of plastic or grounded metal bars to prevent people or animals from touching the high voltage grid.  A light source is fitted inside, often a fluorescent lamp designed to emit both visible and ultraviolet light, which is visible to insects and attracts them.  The light is surrounded by a pair of interleaved bare wire grids or spirals. The distance between adjacent wires is typically about . A high-voltage power supply powered by mains electricity, which may be a simple transformerless voltage multiplier circuit made with diodes and capacitors, generates a voltage of 2,000 volts or more, high enough to conduct through the body of an insect which bridges the two grids, but not high enough to spark across the air gap. Enough electric current flows through the small body of the insect to heat it to a high temperature. The impedance of the power supply and the arrangement of the grid is such that it cannot drive a dangerous current through the body of a human.

text: Bug zappers are usually housed in a protective cage of plastic or grounded metal bars to prevent people or animals from touching the high voltage grid.  A light source is fitted inside, often a

text: fluorescent lamp

text: designed to emit both

text: visible

text: and

text: ultraviolet

text: light, which is visible to insects and attracts them.  The light is surrounded by a pair of interleaved bare wire grids or spirals. The distance between adjacent wires is typically about . A high-voltage

text: power supply

text: powered by

text: mains electricity

text: , which may be a simple

text: transformer

text: less

text: voltage multiplier

text: circuit made with

text: diode

text: s and

text: capacitor

text: s, generates a voltage of 2,000

text: volt

text: s or more, high enough to conduct through the body of an insect which bridges the two grids, but not high enough to spark across the air gap. Enough

text: electric current

text: flows through the small body of the insect to heat it to a high temperature. The

text: impedance

text: of the power supply and the arrangement of the grid is such that it cannot drive a dangerous current through the body of a human.

text: Before modern strobe lights, lenses were used to concentrate the light from a continuous source.  Vertical light rays of the lamp are redirected into a horizontal plane, and horizontally the light is focused into one or a few directions at a time, with the light beam swept around. As a result, in addition to seeing the side of the light beam, the light is directly visible from greater distances, and with an identifying light characteristic.

text: Before modern

text: strobe light

text: s,

text: lenses

text: were used to concentrate the light from a continuous source.  Vertical light rays of the lamp are redirected into a horizontal plane, and horizontally the light is focused into one or a few directions at a time, with the

text: light beam

text: swept around. As a result, in addition to seeing the side of the light beam, the light is directly visible from greater distances, and with an identifying

text: light characteristic

text: A visible light sensor (for example a camera: 0.4 to 0.7 µm) is able to present an image, which can be understood by a human being. Furthermore complex image processing analysis can be executed by computers, which can recognize a flame or even smoke. Unfortunately, a camera can be blinded, like a human, by heavy smoke and by fog. It is also possible to mix visible light information (monitor) with UV or Infrared information, which in this case is made visible. The corona camera is an example of this equipment. In this equipment the information of an UV camera mixed with visible image information. It is used for tracing defects in high voltage equipment and fire detection over high distances.

text: A visible light sensor (for example a camera: 0.4 to 0.7 µm) is able to present an image, which can be understood by a human being. Furthermore complex image processing analysis can be executed by computers, which can recognize a flame or even smoke. Unfortunately, a camera can be blinded, like a human, by heavy smoke and by fog. It is also possible to mix visible light information (monitor) with UV or

text: Infrared

text: information, which in this case is made visible. The corona

text: camera

text: is an example of this equipment. In this equipment the information of an UV camera mixed with visible image information. It is used for tracing defects in

text: high voltage

text: equipment and fire detection over high distances.

text: At this level, the SBEs provide an extremely versatile method that describes linear as well as nonlinear phenomena such as excitonic effects, propagation effects, semiconductor microcavity effects, four-wave-mixing, polaritons in semiconductor microcavities, gain spectroscopy, and so on. One can also generalize the SBEs by including excitation with terahertz (THz) fields that are typically resonant with intraband transitions. One can also quantize the light field and investigate quantum-optical effects that result. In this situation, the SBEs become coupled to the semiconductor luminescence equations.

text: At this level, the SBEs provide an extremely versatile method that describes linear as well as nonlinear phenomena such as

text: exciton

text: ic effects, propagation effects, semiconductor

text: microcavity

text: effects,

text: four-wave-mixing

text: polaritons

text: in semiconductor microcavities,

text: gain spectroscopy

text: , and so on. One can also generalize the SBEs by including excitation with terahertz (THz) fields that are typically resonant with intraband transitions. One can also quantize the light field and investigate

text: quantum-optical

text: effects that result. In this situation, the SBEs become coupled to the

text: semiconductor luminescence equations

text: A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.

text: A pigment is a material that changes the

text: color

text: of reflected or transmitted

text: light

text: as the result of

text: wavelength

text: -selective absorption. This physical process differs from

text: fluorescence

text: phosphorescence

text: , and other forms of

text: luminescence

text: , in which a material emits light.

text: Often task lighting refers to increasing illuminance to better accomplish a specific activity. However, the illuminance level is not the only factor governing visibility. Contrast is also important, and a poorly positioned light source may cause contrast reduction, resulting in loss of visibility. Therefore, it can be argued that the most important purpose of task lighting in the office is not increasing illuminance, but improving contrast. Because task lighting provides focused light where needed, general lighting can be reduced.

text: Often task lighting refers to increasing

text: illuminance

text: to better accomplish a specific activity. However, the illuminance level is not the only factor governing visibility.

text: Contrast

text: is also important, and a poorly positioned light source may cause contrast reduction, resulting in loss of visibility. Therefore, it can be argued that the most important purpose of task lighting in the office is not increasing illuminance, but improving contrast. Because task lighting provides focused light where needed, general lighting can be reduced.

text: Starting in the early 1890s the lights were provided by burning acetylene gas generated in situ from calcium carbide reacting with water. The acetylene-gas illumination system could reliably be turned on and off automatically, enabling automated unattended lighthouses to be used. Once electricity became available, often provided by one or more diesel electric generators in remote locations, the light source was gradually converted to electrical power and the clockworks were run by some type of electric motor. For example, of modern changes, the Chatham Light in Chatham, Massachusetts (near the "elbow" of Cape Cod) the light was converted in 1969 from its Fresnel lens light assembly to a Carlisle & Finch DCB-224 rotating light generating over 2.8 million candela. This is visible for over 20 nautical miles on a clear night and has a self-changing bulb assembly to replace burned-out bulbs.

text: Starting in the early 1890s the lights were provided by burning

text: acetylene

text: gas generated

text: in situ

text: from

text: calcium carbide

text: reacting with water. The acetylene-gas illumination system could reliably be turned on and off automatically, enabling automated unattended lighthouses to be used. Once electricity became available, often provided by one or more

text: diesel

text: electric generator

text: s in remote locations, the light source was gradually converted to electrical power and the clockworks were run by some type of electric motor. For example, of modern changes, the

text: Chatham Light

text: in

text: Chatham, Massachusetts

text: (near the "elbow" of

text: Cape Cod

text: ) the light was converted in 1969 from its Fresnel lens light assembly to a

text: Carlisle & Finch

text: rotating light generating over 2.8 million candela. This is visible for over 20 nautical miles on a clear night and has a self-changing bulb assembly to replace burned-out bulbs.

text: He proposed and joined the international project to build the Infrared Astronomy Satellite (IRAS), a project that included joint efforts from the United States, United Kingdom and the Netherlands, which made the first survey of the infrared sky from space, avoiding all atmospheric interference with observations, starting in 1983. Low served as the chief technologist for the project. After an accident at Jet Propulsion Laboratory destroyed preamplifiers used in the infrared detectors, Low led an effort at Infrared Laboratories to develop improved replacement units to resolve the crisis. IRAS was able to discover in excess of 500,000 infrared sources, including many galaxies, and has discovered shells of debris surrounding stars that show the early stages of planetary formation, with debris similar to that later found as the Kuiper belt that encircles our Solar System beyond the orbit of Neptune. Based on these findings, researchers have concluded that the majority of galactic radiation is emitted in the form of infrared radiation that is generated when light from young stars is absorbed by interstellar dust and then radiated from the dust in the form of heat. In 1984, IRAS found that the galaxy Arp 220, located 300 million light years from Earth, is the closest Ultraluminous Infrared Galaxy, emitting 100 times more energy than the Milky Way galaxy, primarily in the infrared spectrum, even though it is faintly visible by telescope using visible light.

text: He proposed and joined the international project to build the

text: Infrared Astronomy Satellite

text: (IRAS), a project that included joint efforts from the United States,

text: United Kingdom

text: and the

text: Netherlands

text: , which made the first survey of the infrared sky from space, avoiding all atmospheric interference with observations, starting in 1983. Low served as the chief technologist for the project. After an accident at

text: Jet Propulsion Laboratory

text: destroyed

text: preamplifier

text: s used in the infrared detectors, Low led an effort at Infrared Laboratories to develop improved replacement units to resolve the crisis. IRAS was able to discover in excess of 500,000 infrared sources, including many galaxies, and has discovered shells of debris surrounding stars that show the early stages of

text: planetary formation

text: , with debris similar to that later found as the

text: Kuiper belt

text: that encircles our

text: Solar System

text: beyond the orbit of

text: Neptune

text: . Based on these findings, researchers have concluded that the majority of galactic radiation is emitted in the form of infrared radiation that is generated when light from young stars is absorbed by

text: interstellar dust

text: and then radiated from the dust in the form of heat. In 1984, IRAS found that the galaxy

text: Arp 220

text: , located 300 million light years from Earth, is the closest

text: Ultraluminous Infrared Galaxy

text: , emitting 100 times more energy than the

text: Milky Way

text: galaxy, primarily in the infrared spectrum, even though it is faintly visible by telescope using visible light.

text: A flashlight (often called a torch outside North America) is a portable hand-held electric light. Usually, the source of the light is an incandescent light bulb or light-emitting diode (LED). A typical flashlight consists of a light bulb  mounted in a reflector, a transparent cover (sometimes combined with a lens) to protect the light source and reflector, a battery, and a switch.  These are supported and protected by a case.

text: A flashlight (often called a torch outside

text: North America

text: ) is a portable hand-held electric light. Usually, the source of the light is an

text: incandescent light bulb

text: or

text: light-emitting diode

text: (LED). A typical flashlight consists of a light bulb  mounted in a reflector, a transparent cover (sometimes combined with a

text: lens

text: ) to protect the light source and reflector, a

text: battery

text: , and a

text: switch

text: .  These are supported and protected by a case.

text: The current tower is located on the north pier. It is constructed of cast iron, and was first listed in 1927.  The tower is a white cylinder, and the keepers house is separate.  The original lens was a Fifth Order Fresnel lens.  The tower has also been rebuilt as the pier has been extended.  Other changes have involved the placement and configuration of the fog horn.  The present tower is  tall.  The catwalk is one of only four that survive in the State of Michigan.  National Register of Historic Places, Reference # 90000718  The tower is capped with a ten-sided steel lantern.  The light uses a 5,000 candlepower incandescent electric bulb, and has a flashing mechanism which displays "a group occulting white light" over 30 seconds. Its  focal plane is , and is visible for  in clear weather. The "Type C" diaphone is powered by an electric compressor housed in the tower, and emits a group of three blasts every 30 seconds.  There is also a radio beacon.

text: The current tower is located on the north pier. It is constructed of cast iron, and was first listed in 1927.  The tower is a white cylinder, and the keepers house is separate.  The original lens was a Fifth Order

text: Fresnel lens

text: .  The tower has also been rebuilt as the pier has been extended.  Other changes have involved the placement and configuration of the

text: fog horn

text: .  The present tower is  tall.  The catwalk is one of only four that survive in the State of Michigan.

text: National Register of Historic Places

text: , Reference # 90000718  The tower is capped with a ten-sided steel lantern.  The light uses a 5,000 candlepower incandescent electric bulb, and has a flashing mechanism which displays "a group occulting white light" over 30 seconds. Its  focal plane is , and is visible for  in clear weather. The "Type C"

text: diaphone

text: is powered by an electric compressor housed in the tower, and emits a group of three blasts every 30 seconds.  There is also a radio beacon.

text: Westinghouse purchased the US patents rights to the Gaulard-Gibbs transformer and imported several of those as well as Siemens AC generators to begin experimenting with an AC based lighting system in Pittsburgh. William Stanley used the Gaulard-Gibbs design and designs from the ZBD Transformer to develop the first practical transformer. The Westinghouse Electric Company was formed at the beginning of 1886. In March 1886 Stanley, with Westinghouse's backing, installed the first multiple-voltage AC power system, a demonstration incandescent lighting system, in Great Barrington, Massachusetts. Expanded to the point where it could light 23 businesses along main street with very little power loss over 4000 feet, the system used transformers to step 500 AC volts at the street down to 100 volts to power incandescent lamps at each location. By fall of 1886 Westinghouse, Stanley, and Oliver B. Shallenberger had built the first commercial AC power system in the US in Buffalo, New York.

text: Westinghouse purchased the US patents rights to the Gaulard-Gibbs transformer and imported several of those as well as

text: Siemens

text: AC

text: generator

text: s to begin experimenting with an AC based lighting system in

text: Pittsburgh

text: . William Stanley used the Gaulard-Gibbs design and designs from the ZBD Transformer to develop the first practical transformer. The

text: Westinghouse Electric Company

text: was formed at the beginning of 1886. In March 1886 Stanley, with Westinghouse's backing, installed the first multiple-voltage AC power system, a demonstration incandescent lighting system, in Great Barrington, Massachusetts. Expanded to the point where it could light 23 businesses along main street with very little power loss over 4000 feet, the system used transformers to step 500 AC volts at the street down to 100 volts to power incandescent lamps at each location. By fall of 1886 Westinghouse, Stanley, and

text: Oliver B. Shallenberger

text: had built the first commercial AC power system in the US in Buffalo, New York.

text: The discussion on how much UV filtering is necessary in art framing is complex and controversial, driven by conflicting corporate interests. There have so far been no independent organizations, not tied to corporate sponsors, which have presented scientifically verifiable and conclusive evidence to the amount of UV filtering necessary for a glazing to both display and at the same time protect an artwork. On one hand, the issue is complicated by the varying amount of damaging light actually present in an indoor environment (from low level indirect sources to direct daylight). On the other, by the fact that not only UV, but also visible light damages an artwork. According to the National Fenestration Rating Council, only 40% of artwork fading is caused by UV radiation. The remaining damage comes from the visible light, heat, humidity and material chemistry. This means that increasing visible light transmission by an anti-reflective coating actually increases the amount of damaging radiation on an artwork.

text: The discussion on how much

text: UV

text: filtering is necessary in art framing is complex and controversial, driven by conflicting corporate interests. There have so far been no independent organizations, not tied to corporate sponsors, which have presented scientifically verifiable and conclusive evidence to the amount of UV filtering necessary for a glazing to both display and at the same time protect an artwork. On one hand, the issue is complicated by the varying amount of damaging light actually present in an indoor environment (from low level indirect sources to direct daylight). On the other, by the fact that not only

text: UV

text: , but also

text: visible light

text: damages an artwork. According to the National Fenestration Rating Council, only 40% of artwork fading is caused by UV radiation. The remaining damage comes from the visible light, heat, humidity and material chemistry. This means that increasing visible light transmission by an anti-reflective coating actually increases the amount of damaging radiation on an artwork.

text: In 1994, the principles behind optical and thermoluminescence dating were extended to include surfaces made of granite, basalt and sandstone, such as carved rock from ancient monuments and artifacts.  Ioannis Liritzis, the initiator of ancient buildings luminescence dating, has shown this in several cases of various monuments.

text: In 1994, the principles behind optical and

text: thermoluminescence dating

text: were extended to include surfaces made of granite, basalt and sandstone, such as carved rock from ancient monuments and artifacts.

text: Ioannis Liritzis

text: , the initiator of ancient buildings luminescence dating, has shown this in several cases of various monuments.

text: In 2015 visible light joined microwave and infrared NIMs in propagating light in only one direction. ("mirrors" instead reduce light transmission in the reverse direction, requiring low light levels behind the mirror to work.)

text: In 2015 visible light joined microwave and infrared NIMs in propagating light in only one direction. ("

text: mirrors

text: " instead reduce light transmission in the reverse direction, requiring low light levels behind the mirror to work.)

text: Each of these three aspects is looked at in considerable detail when the lighting designer is at work. In aesthetic appeal, the lighting designer attempts to raise the general attractiveness of the design, measure whether it should be subtly blended into the background or whether it should stand out, and assess what kind of emotions the lighting should evoke. The functional aspects of the project can encompass the need for the project to be visible (by night mostly, but also by day), the impact of daylight on the project and safety issues (glare, colour confusion etc.).

text: Each of these three aspects is looked at in considerable detail when the lighting designer is at work. In aesthetic appeal, the lighting designer attempts to raise the general attractiveness of the design, measure whether it should be subtly blended into the background or whether it should stand out, and assess what kind of

text: emotions

text: the lighting should evoke. The functional aspects of the project can encompass the need for the project to be visible (by night mostly, but also by day), the impact of

text: daylight

text: on the project and

text: safety

text: issues (

text: glare

text: , colour confusion etc.).

text: Both the mycelia and the fruit bodies of M. haematopus (both young and mature specimens) are reported to be bioluminescent. However, the luminescence is quite weak, and not visible to the dark-adapted eye; in one study, light emission was detectable only after 20 hours of exposure to X-ray film. Although the biochemical basis of bioluminescence in M. haematopus has not been scientifically investigated, in general, bioluminescence is caused by the action of luciferases, enzymes that produce light by the oxidation of a luciferin (a pigment). The biological purpose of bioluminescence in fungi is not definitively known, although several hypotheses have been suggested: it may help attract insects to help with spore dispersal, it may be a by-product of other biochemical functions, or it may help deter heterotrophs that might consume the fungus.

text: Both the mycelia and the fruit bodies of M. haematopus (both young and mature specimens) are reported to be

text: bioluminescent

text: . However, the luminescence is quite weak, and not visible to the

text: dark-adapted

text: eye; in one study, light emission was detectable only after 20 hours of

text: exposure

text: to

text: X-ray film

text: . Although the biochemical basis of bioluminescence in M. haematopus has not been scientifically investigated, in general, bioluminescence is caused by the action of

text: luciferase

text: s, enzymes that produce light by the

text: oxidation

text: of a

text: luciferin

text: (a

text: pigment

text: ). The biological purpose of bioluminescence in fungi is not definitively known, although several hypotheses have been suggested: it may help attract insects to help with spore dispersal, it may be a by-product of other biochemical functions, or it may help deter

text: heterotroph

text: s that might consume the fungus.

text: Ottoman illumination covers non-figurative painted or drawn decorative art in books or on sheets in muraqqa or albums, as opposed to the figurative images of the Ottoman miniature. It was a part of the Ottoman Book Arts together with the Ottoman miniature (taswir), calligraphy (hat), Islamic calligraphy, bookbinding (cilt) and paper marbling (ebru). In the Ottoman Empire, illuminated and illustrated manuscripts were commissioned by the Sultan or the administrators of the court. In Topkapi Palace, these manuscripts were created by the artists working in Nakkashane, the atelier of the miniature and illumination artists. Both religious and non-religious books could be illuminated. Also sheets for albums levha consisted of illuminated calligraphy (hat) of tughra, religious texts, verses from poems or proverbs, and purely decorative drawings.

text: Ottoman illumination

text: covers non-figurative painted or drawn decorative art in books or on sheets in

text: muraqqa

text: or albums, as opposed to the figurative images of the

text: Ottoman miniature

text: . It was a part of the Ottoman Book Arts together with the Ottoman miniature (taswir), calligraphy (hat),

text: Islamic calligraphy

text: , bookbinding (cilt) and

text: paper marbling

text: (ebru). In the Ottoman Empire,

text: illuminated and illustrated manuscripts

text: were commissioned by the Sultan or the administrators of the court. In

text: Topkapi Palace

text: , these manuscripts were created by the artists working in Nakkashane, the atelier of the miniature and illumination artists. Both religious and non-religious books could be illuminated. Also sheets for albums levha consisted of illuminated calligraphy (hat) of

text: tughra

text: , religious texts, verses from poems or proverbs, and purely decorative drawings.

text: Notable Galactic H II regions include the Orion Nebula, the Eta Carinae Nebula, and the Berkeley 59 / Cepheus OB4 Complex. The Orion Nebula, about 500 pc (1,500 light-years) from Earth, is part of OMC-1, a GMC that, if visible, would be seen to fill most of the constellation of Orion. The Horsehead Nebula and Barnard's Loop are two other illuminated parts of this cloud of gas.<ref name=Horsehead>

text: Notable Galactic H II regions include the Orion Nebula, the

text: Eta Carinae Nebula

text: , and the

text: Berkeley 59 / Cepheus OB4 Complex

text: . The Orion Nebula, about 500

text: pc

text: (1,500 light-years) from Earth, is part of

text: , a GMC that, if visible, would be seen to fill most of the constellation of

text: Orion

text: . The

text: Horsehead Nebula

text: and

text: Barnard's Loop

text: are two other illuminated parts of this cloud of gas.<ref name=Horsehead>

text: The advice to cover one's exposed skin with anything that can cast a shadow, like the picnic blanket and newspaper used by the family in the film, may seem absurd at first when one considers the capabilities of a nuclear weapon, but even the thinnest of barriers such as cloth or plant leaves would reduce the severity of burns on the skin from the thermal radiation( the thermal radiation/flash is light, similar in average emission spectrum/color to sun light, emitting in the ultraviolet, visible light, and infrared range but with a higher light intensity than sunlight, with this combination of light rays capable of delivering radiant burning energy to exposed skin areas. While the duration of emittance of this burning thermal radiation, which can be experienced by people within range, increases with yield, it is usually at least a few seconds long.) Furthermore, great importance is given to closing eyelids and covering the location of the eyes as temporary and permanent flash blindness is a risk potential without this covering, especially at night. A photograph taken about 1.3 km from the hypocenter of the Hiroshima bomb explosion showed that the shadowing effect of leaves from a nearby shrub protected a wooden utilities pole from charring discoloration due to the burst of thermal radiation, however the rest of the telephone pole, not under the protection of the leaves, was charred almost completely black.

text: The advice to cover one's exposed skin with anything that can cast a shadow, like the picnic blanket and newspaper used by the family in the

text: film

text: , may seem absurd at first when one considers the capabilities of a nuclear weapon, but even the thinnest of barriers such as cloth or plant leaves would reduce the severity of burns on the skin from the

text: thermal radiation

text: ( the thermal radiation/flash is

text: light

text: , similar in average

text: emission spectrum

text: /color to

text: sun light

text: , emitting in the

text: ultraviolet

text: visible light

text: , and

text: infrared

text: range but with a higher

text: light intensity

text: than sunlight, with this combination of light rays capable of delivering

text: radiant

text: burning energy to exposed skin areas. While the duration of

text: emittance

text: of this burning thermal radiation, which can be experienced by people within range, increases with yield, it is usually at least a few seconds long.) Furthermore, great importance is given to closing

text: eyelid

text: s and covering the location of the eyes as temporary and permanent

text: flash blindness

text: is a risk potential without this covering, especially at night. A photograph taken about 1.3 km from the

text: hypocenter

text: of the

entity_name: Atomic bombings of Hiroshima and Nagasaki

text: Hiroshima bomb explosion

text: showed that the shadowing effect of

text: leaves

text: from a nearby

text: shrub

text: protected a wooden

text: utilities

text: pole from

text: charring

text: discoloration due to the burst of thermal radiation, however the rest of the telephone pole, not under the protection of the leaves, was

text: charred almost completely black

text: The CRI of a light source does not indicate the apparent color of the light source; that information is under the rubric of the correlated color temperature (CCT). The CRI is determined by the light source's spectrum. The pictures on the right show the continuous spectrum of an incandescent lamp and the discrete line spectrum of a fluorescent lamp; the former lamp has the higher CRI.

text: The CRI of a light source does not indicate the apparent color of the light source; that information is under the rubric of the

text: correlated color temperature

text: (CCT). The CRI is determined by the light source's

text: spectrum

text: . The pictures on the right show the continuous spectrum of an

text: incandescent lamp

text: and the discrete line spectrum of a

text: fluorescent lamp

text: ; the former lamp has the higher CRI.

text: Nineteenth-century technology revolutionized stage lighting, which until then had been primitive. The introduction of gas lighting was the first step. In 1816, Philadelphia's Chestnut Street Theater became the earliest gas-lit playhouse in the world. The introduction of gas lighting revolutionized stage lighting. It provided a somewhat more natural and adequate light for the playing and the scenic space upstage of the proscenium arch. However, this new richness in lighting provided difficulties at first. Though scenic painters had to learn to subdue their colors to the increased candle-power, the brightness only further highlight the disparity between three-dimensional set pieces and their two-dimensional backdrop and led to the latter's eventual decline. The advent of limelight, also known as Drummond light, also effectively introduced spotlighting to theater. Thomas Edison's electric incandescent lamp, invented in 1879, was the next step. It made electricity the most flexible, most controllable, and safest form of lighting, in the twentieth century, it would make stage lighting design a true art. These new means of illumination tremendously increased the control over stage light and stimulated interest in imitating lighting phenomena of nature.

text: Nineteenth-century technology revolutionized stage lighting, which until then had been primitive. The introduction of

text: gas lighting

text: was the first step. In 1816, Philadelphia's Chestnut Street Theater became the earliest gas-lit playhouse in the world. The introduction of gas lighting revolutionized stage lighting. It provided a somewhat more natural and adequate light for the playing and the scenic space upstage of the proscenium arch. However, this new richness in lighting provided difficulties at first. Though scenic painters had to learn to subdue their colors to the increased candle-power, the brightness only further highlight the disparity between three-dimensional set pieces and their two-dimensional backdrop and led to the latter's eventual decline. The advent of

text: limelight

text: , also known as

text: Drummond light

text: , also effectively introduced

text: spotlighting

text: to theater.

text: Thomas Edison

text: 's electric incandescent lamp, invented in 1879, was the next step. It made electricity the most flexible, most controllable, and safest form of lighting, in the twentieth century, it would make stage lighting design a true art. These new means of illumination tremendously increased the control over stage light and stimulated interest in imitating lighting phenomena of nature.

text: Photo-luminescent signs are sometimes wrongfully described as being reflective. A reflective material will only return ambient light for as long as the light source is supplied, rather than storing energy and releasing it over a period of time. But, many fire extinguishers and extinguisher-mounting posts have strips of retroreflective adhesive tape placed on them to facilitate their location in situations where only emergency lighting or flashlights are available.

text: Photo-luminescent signs are sometimes wrongfully described as being

text: reflective

text: . A reflective material will only return ambient light for as long as the light source is supplied, rather than storing energy and releasing it over a period of time. But, many fire extinguishers and extinguisher-mounting posts have strips of

text: retroreflective

text: adhesive tape placed on them to facilitate their location in situations where only emergency lighting or

text: flashlight

text: s are available.

text: D65 corresponds roughly to the average midday light in Western Europe / Northern Europe (comprising both direct sunlight and the light diffused by a clear sky), hence it is also called a daylight illuminant. As any standard illuminant is represented as a table of averaged spectrophotometric data, any light source which statistically has the same relative spectral power distribution (SPD) can be considered a D65 light source. There are no actual D65 light sources, only simulators. The quality of a simulator can be assessed with the CIE Metamerism Index.

text: D65 corresponds roughly to the average midday light in

text: Western Europe

text: Northern Europe

text: (comprising both direct sunlight and the light diffused by a clear sky), hence it is also called a

text: daylight

text: illuminant. As any standard illuminant is represented as a table of

text: averaged

text: spectrophotometric

text: data, any light source which statistically has the same relative

text: spectral power distribution

text: (SPD) can be considered a D65 light source. There are no actual D65 light sources, only simulators. The quality of a simulator can be assessed with the CIE

text: Metamerism

text: Index.

text: When you choose not to put energy to work, you save multiples of energy at the point where the primary fuel was sourced. Put another way, the amount of energy saved by not flicking on the wall switch does not translate into an equal amount of energy saved at a coal mine. The leverage up the inefficient supply chain of energy is such that multiples of that energy is saved in terms of the coal not needed to generate your electricity. Consider a simple example. For an incandescent light bulb the multiplier is approximately 50-to-one. A conscious decision to forfeit one quantum of light energy in your home means that 50 times that amount of primary energy is conserved at the source.

text: When you choose not to put energy to work, you save multiples of energy at the point where the primary fuel was sourced. Put another way, the amount of energy saved by not flicking on the wall switch does not translate into an equal amount of energy saved at a

text: coal mine

text: . The leverage up the inefficient supply chain of energy is such that multiples of that energy is saved in terms of the

text: coal

text: not needed to generate your

text: electricity

text: . Consider a simple example. For an

text: incandescent light bulb

text: the multiplier is approximately 50-to-one. A conscious decision to forfeit one quantum of light energy in your home means that 50 times that amount of primary energy is conserved at the source.

text: Another type of finder commonly found on amateur telescopes is known as a reflector (reflex) sight. This non-magnifying sight (technically not a "scope") uses a type of beam splitter to "reflect" a reticle generated by collimating optics into the users field of view. The view of the sky seen through the sight is just what can be seen with the naked eye with an illuminated crosshair or dot seeming to float in space at infinity. These crosshairs are generally illuminated by a small LED. Reflex sights are most useful for locating bright objects visible to the naked eye such as stars, planets, or nebulae. Since the sight uses a beam splitter "window", instead of an optical telescope with the ability to gather light, objects dimmer than the naked eye limit can not be seen through it. The lack of an optical telescope's magnification can make it harder to discern the difference between objects, such as stars and small angular size nebulae. They can also be used when finding dimmer objects by using the object's known position relative to brighter objects as a reference.

text: Another type of finder commonly found on amateur telescopes is known as a

text: reflector (reflex) sight

text: . This non-magnifying

text: sight

text: (technically not a "scope") uses a type of

text: beam splitter

text: to "reflect" a reticle generated by

text: collimating optics

text: into the users field of view. The view of the sky seen through the sight is just what can be seen with the naked eye with an illuminated crosshair or dot seeming to float in space at

text: infinity

text: . These crosshairs are generally illuminated by a small LED. Reflex sights are most useful for locating bright objects visible to the naked eye such as stars,

text: planets

text: , or

text: nebulae

text: . Since the sight uses a beam splitter "window", instead of an optical telescope with the ability to

text: gather light

text: , objects dimmer than the naked eye limit can not be seen through it. The lack of an optical telescope's magnification can make it harder to discern the difference between objects, such as stars and small angular size nebulae. They can also be used when finding dimmer objects by using the object's known position relative to brighter objects as a reference.

text: The incandescent light bulb has a spectrum overlapping the black body spectra of the sun and the earth. Some of the photons emitted by a tungsten light bulb filament at 3000 K are in the visible spectrum. Most of the energy is associated with photons of longer wavelengths; these do not help a person see, but still transfer heat to the environment, as can be deduced empirically by observing an incandescent light bulb. Whenever EM radiation is emitted and then absorbed, heat is transferred. This principle is used in microwave ovens, laser cutting, and RF hair removal.

text: The

text: incandescent light bulb

text: has a spectrum overlapping the black body spectra of the sun and the earth. Some of the photons emitted by a tungsten light bulb filament at

text: 3000 K

text: are in the visible spectrum. Most of the energy is associated with photons of longer wavelengths; these do not help a person see, but still transfer heat to the environment, as can be deduced empirically by observing an incandescent light bulb. Whenever EM radiation is emitted and then absorbed, heat is transferred. This principle is used in

text: microwave oven

text: s,

text: laser cutting

text: , and

text: RF hair removal

text: Noble gases are commonly used in lighting because of their lack of chemical reactivity. Argon, mixed with nitrogen, is used as a filler gas for incandescent light bulbs. Krypton is used in high-performance light bulbs, which have higher color temperatures and greater efficiency, because it reduces the rate of evaporation of the filament more than argon; halogen lamps, in particular, use krypton mixed with small amounts of compounds of iodine or bromine. The noble gases glow in distinctive colors when used inside gas-discharge lamps, such as "neon lights". These lights are called after neon but often contain other gases and phosphors, which add various hues to the orange-red color of neon. Xenon is commonly used in xenon arc lamps which, due to their nearly continuous spectrum that resembles daylight, find application in film projectors and as automobile headlamps.

text: Noble gases are commonly used in

text: lighting

text: because of their lack of chemical reactivity. Argon, mixed with nitrogen, is used as a filler gas for

text: incandescent light bulb

text: s. Krypton is used in high-performance light bulbs, which have higher

text: color temperature

text: s and greater efficiency, because it reduces the rate of evaporation of the filament more than argon;

text: halogen lamps

text: , in particular, use krypton mixed with small amounts of compounds of

text: iodine

text: or

text: bromine

text: . The noble gases glow in distinctive colors when used inside

text: gas-discharge lamp

text: s, such as "

text: neon lights

text: ". These lights are called after neon but often contain other gases and

text: phosphor

text: s, which add various hues to the orange-red color of neon. Xenon is commonly used in

text: xenon arc lamp

text: s which, due to their nearly

text: continuous spectrum

text: that resembles daylight, find application in film projectors and as automobile headlamps.

text: Visible light, a small portion of the electromagnetic spectrum, encompasses wavelengths between 380-750 nanometers, which humans perceive as the colors of the spectrum: red, orange, yellow, green, blue, indigo, and violet. Light behaves according to a well-defined set of rules: it travels in straight lines, unless otherwise refracted or reflected by another object, or curved by gravity.

text: Visible

text: light

text: , a small portion of the electromagnetic spectrum, encompasses wavelengths between 380-750 nanometers, which humans perceive as the colors of the spectrum: red, orange, yellow, green, blue, indigo, and violet. Light behaves according to a well-defined set of rules: it travels in straight lines, unless otherwise refracted or reflected by another object, or curved by gravity.

text: Approach lighting systems are designed to allow the pilot to quickly and positively identify visibility distances in Instrument meteorological conditions.  For example, if the aircraft is at the middle marker, and the middle marker is located 3600 feet from the threshold, the Decision Bar is 2600 feet ahead.  If the procedure calls for at least half a statute mile flight visibility (roughly 2600 feet),  spotting the Decision Bar at the marker would indicate enough flight visibility to continue the procedure.  In addition, the shorter bars before and after the Decision Bar are spaced either 100 feet or 200 feet apart, depending on the ALS type.  The number of short bars the pilot can see can be used to determine flight visibility.  Approaches with lower minimums use the more precise 100-foot spacing systems for more accurate identification of visibility.

text: Approach lighting systems are designed to allow the pilot to quickly and positively identify visibility distances in

text: Instrument meteorological conditions

text: .  For example, if the aircraft is at the middle marker, and the middle marker is located 3600 feet from the threshold, the Decision Bar is 2600 feet ahead.  If the procedure calls for at least half a statute mile flight visibility (roughly 2600 feet),  spotting the Decision Bar at the marker would indicate enough flight visibility to continue the procedure.  In addition, the shorter bars before and after the Decision Bar are spaced either 100 feet or 200 feet apart, depending on the ALS type.  The number of short bars the pilot can see can be used to determine flight visibility.  Approaches with lower minimums use the more precise 100-foot spacing systems for more accurate identification of visibility.

text: - For visible light,

text: - For visible light,

text: Perhaps bolometry should in some cases be combined with other detection techniques (luminescence?) in order to produce a primary fast signal as timing strobe. If light is used as a complementary signature, particle identification can be achieved through the heat-light ratio, where nucleus recoil is expected to be less luminescent than ionizing particles. The success of such a development would open the way to unprecedented achievements in background rejection for rare event experiments.

text: On June 14, 2004, a $17 million upgrade was unveiled that would feature a 12.5-million LED display and more color combinations than the original display, which was composed of incandescent lighting.

text: On June 14, 2004, a $17 million upgrade was unveiled that would feature a 12.5-million

text: LED

text: display and more color combinations than the original display, which was composed of

text: incandescent light

text: ing.

text: The researchers had suggested that the motion may be a remnant of the influence of no-longer-visible regions of the universe prior to inflation. Telescopes cannot see events earlier than about 380,000 years after the Big Bang, when the universe became transparent (the cosmic microwave background); this corresponds to the particle horizon at a distance of about 46 billion (4.6×10) light years. Since the matter causing the net motion in this proposal is outside this range, it would in a certain sense be outside our visible universe; however, it would still be in our past light cone.

text: The researchers had suggested that the motion may be a remnant of the influence of no-longer-visible regions of the universe prior to

text: inflation

text: . Telescopes cannot see events earlier than about 380,000 years after the

text: Big Bang

text: , when the universe became transparent (the

text: cosmic microwave background

text: ); this corresponds to the

text: particle horizon

text: at a distance of about 46 billion (4.6×10)

text: light year

text: s. Since the matter causing the net motion in this proposal is outside this range, it would in a certain sense be outside our

text: visible universe

text: ; however, it would still be in our past

text: light cone

text: The House of Blues concert hall was built in the shell of the complex's long-disused movie theater; similarly, the hotel was built in what was once the Marina City office building.  In order to accommodate Smith and Wollensky, the former skating rink was demolished and pedestrian and vehicular access to the residential towers and the raised common plaza were redesigned. In 2006, decorative lighting, visible for miles, was installed around the circular roofs of the mechanical sheds that top each tower; the towers had not contained any such lighting since the 1960s.

text: DDOT regulations provide for the use of three type of lamps:  sodium-vapor, metal halide, mercury-vapor, LED, fluorescent, and incandescent. Sodium-vapor lamps are used almost universally throughout the city, except for the Monumental Core. Metal halide lamps are used primarily in the Monumental Core. LED lamps are being introduced, and mercury-vapor and incandescent lights are being phased out in favor of sodium-vapor lamps. Fluorescent lighting is used almost exclusively for underpasses.

text: DDOT regulations provide for the use of three type of lamps:  sodium-vapor,

text: metal halide

text: mercury-vapor

text: LED

text: fluorescent

text: , and

text: incandescent

text: . Sodium-vapor lamps are used almost universally throughout the city, except for the

entity_section: The National Mall and the "monumental core"

text: Monumental Core

text: . Metal halide lamps are used primarily in the Monumental Core. LED lamps are being introduced, and mercury-vapor and incandescent lights are being phased out in favor of sodium-vapor lamps. Fluorescent lighting is used almost exclusively for underpasses.

text: Tritium light sources are most often seen as "permanent" illumination for the hands of wristwatches intended for diving, nighttime, or tactical use. They are additionally used in glowing novelty keychains, in self-illuminated exit signs, and formerly in fishing lures. They are favored by the military for applications where a power source may not be available, such as for instrument dials in aircraft, compasses, lights for map reading, and sights for weapons.

text: Tritium light sources are most often seen as "permanent" illumination for the hands of

text: wristwatches

text: intended for diving, nighttime, or tactical use. They are additionally used in glowing

text: novelty

text: keychain

text: s, in self-illuminated

text: exit sign

text: s, and formerly in fishing lures. They are favored by the military for applications where a power source may not be available, such as for instrument

text: dial

text: s in aircraft,

text: compass

text: es, lights for map reading, and sights for weapons.

text: Secondly, although the carbon arc lamp was bright, and relatively economical for the illumination produced, individual lamps were expensive and complicated, although powerful. This encouraged their use as the minimum number of large lamps to cover an entire work site. As the arc lamp also has a very small source of light, this gave a particularly harsh lighting. There was a sudden contrast between the illuminated and shadow areas, especially where a point was only in sight of a single lamp. This was recognised as a trip and obstacle hazard, as well as making even the light areas difficult to work under. The Wells light was specifically contrasted with the point-source of the arc lamp and the relatively shadow-free illumination was cited as an advantage in their adverts. Because the smaller Wells lights were so portable, they could be carried into the best position to illuminate a deep shaft or inside a ship's hull.

text: An LED lamp is a light-emitting diode (LED) product which is assembled into a lamp (or light bulb) for use in lighting fixtures. LED lamps have a lifespan and electrical efficiency which are several times greater than incandescent lamps, and are significantly more efficient than most fluorescent lamps, with some chips able to emit more than 300 lumens per watt (as claimed by Cree and some other LED manufacturers). The LED lamp market is projected to grow by more than twelve-fold over the next decade, from $2 billion in the beginning of 2014 to $25 billion in 2023, a compound annual growth rate (CAGR) of 25%. As of 2016, LEDs use only about 10% of the energy an incandescent lamp requires.

text: An LED lamp is a

text: light-emitting diode

text: (LED) product which is assembled into a

text: lamp

text: (or

text: light bulb

text: ) for use in

text: lighting fixture

text: s. LED lamps have a lifespan and

text: electrical efficiency

text: which are several times greater than

text: incandescent lamps

text: , and are significantly more efficient than most

text: fluorescent lamps

text: , with some chips able to emit more than 300 lumens per watt (as claimed by Cree and some other LED manufacturers). The LED lamp market is projected to grow by more than twelve-fold over the next decade, from $2 billion in the beginning of 2014 to $25 billion in 2023, a

text: compound annual growth rate

text: (CAGR) of 25%. As of 2016, LEDs use only about 10% of the energy an incandescent lamp requires.

text: They are easily visible under 100x magnification (use the 10x or "scanning" objective on most compound microscopes) and their scintillons luminesce in response to surface tension and acidity. Luminescence is under circadian regulation, peaking at night. Because of this obvious rhythms (and also due to the fact that most its activities, physiological and molecular, are rhythmic) L. polyedrum has been a model organism for studying clocks in single cells.

text: They are easily visible under 100x magnification (use the 10x or "scanning" objective on most compound microscopes) and their

text: scintillon

text: s luminesce in response to surface tension and acidity. Luminescence is under circadian regulation, peaking at night. Because of this obvious rhythms (and also due to the fact that most its activities, physiological and molecular, are rhythmic) L. polyedrum has been a model organism for studying clocks in single cells.

text: A luminous flame is a burning flame which is brightly visible. Much of its output is in the form of visible light, as well as heat or light in the non-visible wavelengths.

text: A luminous flame is a burning

text: flame

text: which is brightly visible. Much of its output is in the form of

text: visible light

text: , as well as heat or light in the non-visible wavelengths.

text: Refraction of light entering the mask makes objects appear about 34% bigger and 25% nearer when underwater. As the diver descends in clean water, the water acts as a colour filter eliminating the red end of the visible spectrum of the sunlight entering the water leaving only the blue end of the spectrum. Depending on the depth and clarity of the water, eventually all sunlight is blocked and the diver has to rely on artificial light sources to see underwater.

text: Refraction

text: of light entering the mask makes objects appear about 34% bigger and 25% nearer when

text: underwater

text: . As the diver descends in clean water, the water acts as a

text: colour

text: filter

text: eliminating the

text: red

text: end of the

text: visible spectrum

text: of the

text: sunlight

text: entering the water leaving only the

text: blue

text: end of the spectrum. Depending on the depth and clarity of the water, eventually all sunlight is blocked and the diver has to rely on artificial

text: light source

text: s to see underwater.

text: Color temperature for white light sources also affects their use for certain applications. The color temperature of a white light source is the temperature in Kelvin of a theoretical black body emitter that most closely matches the spectral characteristics  of the lamp. An incandescent bulb has a color temperature around 2800 to 3000 Kelvin; daylight is around 6400 Kelvin. Lower color temperature lamps have relatively more energy in the yellow and red part of the visible spectrum, while high color temperatures correspond to lamps with more of a blue-white appearance.  For critical inspection or color matching tasks, or for retail displays of food and clothing, the color temperature of the lamps will be selected for the best overall lighting effect.

text: Color temperature

text: for white light sources also affects their use for certain applications. The color temperature of a white light source is the temperature in

text: Kelvin

text: of a theoretical

text: black body

text: emitter that most closely matches the spectral characteristics  of the lamp. An incandescent bulb has a color temperature around 2800 to 3000 Kelvin; daylight is around 6400 Kelvin. Lower color temperature lamps have relatively more energy in the yellow and red part of the visible spectrum, while high color temperatures correspond to lamps with more of a blue-white appearance.  For critical inspection or color matching tasks, or for retail displays of food and clothing, the color temperature of the lamps will be selected for the best overall lighting effect.

text: Many of the installations of the lamps were for testing purposes only, but there remain a few sites where the lamps are in use as the primary lighting source.  Perhaps the most visible of these would be the glass atria in the National Air and Space Museum.

text: Many of the installations of the lamps were for testing purposes only, but there remain a few sites where the lamps are in use as the primary lighting source.  Perhaps the most visible of these would be the glass

text: atria

text: in the

text: National Air and Space Museum

text: Civilian commercial airliners also have other non-navigational lights. These include logo lights, which illuminate the company logo on the tail fin. These lights are optional to turn on, though most pilots switch them on at night to increase visibility from other aircraft. Modern airliners also have a wing light. These are positioned on the outer side just in front of the engine cowlings on the fuselage. These are not required to be on, but in some cases pilots turn these lights on for engine checks and also while passengers board the aircraft for better visibility of the ground near the aircraft.

text: Civilian commercial airliners also have other non-navigational lights. These include logo lights, which illuminate the company logo on the tail fin. These lights are optional to turn on, though most pilots switch them on at night to increase visibility from other aircraft. Modern airliners also have a wing light. These are positioned on the outer side just in front of the engine cowlings on the

text: fuselage

text: . These are not required to be on, but in some cases pilots turn these lights on for engine checks and also while passengers board the aircraft for better visibility of the ground near the aircraft.

text: Art historians classify illuminated manuscripts into their historic periods and types, including (but not limited to) Late Antique, Insular, Carolingian manuscripts, Ottonian manuscripts, Romanesque manuscripts, Gothic manuscripts, and Renaissance manuscripts. There are a few examples from later periods. The type of book that was most often heavily and richly illuminated, sometimes known as a "display book", varied between periods. In the first millennium, these were most likely to be Gospel Books, such as the Lindisfarne Gospels and the Book of Kells. The Romanesque period saw the creation of many huge illuminated complete Bibles – one in Sweden requires three librarians to lift it. Many Psalters were also heavily illuminated in both this and the Gothic period. Single cards or posters of vellum, leather or paper were in wider circulation with short stories or legends on them about the lives of saints, chivalry knights or other mythological figures, even criminal, social or miraculous occurrences; popular events much freely used by story tellers and itinerant actors to support their plays. Finally, the Book of Hours, very commonly the personal devotional book of a wealthy layperson, was often richly illuminated in the Gothic period. Other books, both liturgical and not, continued to be illuminated at all periods. The Byzantine world also continued to produce manuscripts in its own style, versions of which spread to other Orthodox and Eastern Christian areas. See Medieval art for other regions, periods and types.  Reusing parchments by scraping the surface and reusing them was a common practice; the traces often left behind of the original text are known as palimpsests.

text: Art historians classify illuminated manuscripts into their historic periods and types, including (but not limited to) Late Antique,

text: Insular

text: Carolingian manuscripts

text: Ottonian manuscripts

text: Romanesque manuscripts

text: Gothic manuscripts

text: , and

text: Renaissance manuscripts

text: . There are a few examples from later periods. The type of book that was most often heavily and richly illuminated, sometimes known as a "display book", varied between periods. In the first millennium, these were most likely to be

text: Gospel Book

text: s, such as the

text: Lindisfarne Gospels

text: and the

text: Book of Kells

text: . The Romanesque period saw the creation of many huge illuminated complete

text: Bible

text: s – one in Sweden requires three librarians to lift it. Many

text: Psalter

text: s were also heavily illuminated in both this and the Gothic period. Single cards or posters of vellum, leather or paper were in wider circulation with short stories or legends on them about the lives of saints, chivalry knights or other mythological figures, even criminal, social or miraculous occurrences; popular events much freely used by story tellers and itinerant actors to support their plays. Finally, the

text: Book of Hours

text: , very commonly the personal devotional book of a wealthy layperson, was often richly illuminated in the Gothic period. Other books, both liturgical and not, continued to be illuminated at all periods. The Byzantine world also continued to produce manuscripts in its own style, versions of which spread to other Orthodox and Eastern Christian areas. See

text: Medieval art

text: for other regions, periods and types.  Reusing parchments by scraping the surface and reusing them was a common practice; the traces often left behind of the original text are known as

text: palimpsests

text: When a material is heated to incandescence it emits light that is characteristic of the atomic makeup of the material.Particular light frequencies give rise to sharply defined bands on the scale which can be thought of as fingerprints. For example, the element sodium has a very characteristic double yellow band known as the Sodium D-lines at 588.9950 and 589.5924 nanometers, the color of which will be familiar to anyone who has seen a low pressure sodium vapor lamp.

text: When a material is heated to

text: incandescence

text: it emits

text: light

text: that is characteristic of the atomic makeup of the material.Particular light frequencies give rise to sharply defined bands on the scale which can be thought of as fingerprints. For example, the element

text: sodium

text: has a very characteristic double yellow band known as the Sodium D-lines at 588.9950 and 589.5924 nanometers, the color of which will be familiar to anyone who has seen a low pressure

text: sodium vapor lamp

text: Several different types of light sources exist, each having different properties that affect their appropriateness for certain tasks, particularly efficiency and spectral power distribution. It is often the case that inappropriate light sources have been selected for a task, either due to ignorance or because more sophisticated light sources were unavailable at the time of installation. Therefore, badly chosen light sources often contribute unnecessarily to light pollution and energy waste. By re-assessing and changing the light sources used, it is often possible to reduce energy use and pollutive effects while simultaneously greatly improving efficiency and visibility.

text: High-pressure sodium lights are a more efficient type of HID lighting than metal halides. HPS bulbs emit light in the yellow/red visible light as well as small portions of all other visible light. Since HPS grow lights deliver more energy in the red part of the light spectrum, they may promote blooming and fruiting. They are used as a supplement to natural daylight in greenhouse lighting and full-spectrum lighting(metal halide) or, as a standalone source of light for indoors/grow chambers.

text: High-pressure sodium lights

text: are a more efficient type of HID lighting than metal halides. HPS bulbs emit light in the yellow/red visible light as well as small portions of all other visible light. Since HPS grow lights deliver more energy in the red part of the light spectrum, they may promote blooming and fruiting. They are used as a supplement to natural daylight in greenhouse lighting and full-spectrum lighting(metal halide) or, as a standalone source of light for indoors/grow chambers.

text: Except for light that comes directly from the sun, most of the light in the day sky is caused by scattering, which is dominated by a small-particle limit called Rayleigh Scattering. The scattering due to molecule sized particles (as in air) is greater in the forward and backward directions than it is in the lateral direction. Scattering is significant for light at all visible wavelengths but is stronger at the shorter (bluer) end of the visible spectrum, meaning that the scattered light is bluer than its source, the sun. The remaining sunlight, having lost some of its short wavelength components, appears slightly less blue.

text: Except for

text: light

text: that comes directly from the sun, most of the light in the day sky is caused by

text: scattering

text: , which is dominated by a small-particle limit called

text: Rayleigh Scattering

text: . The scattering due to

text: molecule

text: sized particles (as in air) is greater in the forward and backward directions than it is in the lateral direction. Scattering is significant for light at all visible wavelengths but is stronger at the shorter (bluer) end of the

text: visible spectrum

text: , meaning that the scattered light is bluer than its source, the

text: sun

text: . The remaining sunlight, having lost some of its short wavelength components, appears slightly less blue.

text: Low-key lighting is a style of lighting for photography, film or television. It is a necessary element in creating a chiaroscuro effect. Traditional photographic lighting, three-point lighting uses a key light, a fill light, and a back light for illumination. Low-key lighting often uses only one key light, optionally controlled with a fill light or a simple reflector.

text: Low-key lighting is a style of

text: lighting

text: for

text: photography

text: film

text: or

text: television

text: . It is a necessary element in creating a

text: chiaroscuro

text: effect. Traditional photographic

text: lighting

text: three-point lighting

text: uses a

text: key light

text: , a

text: fill light

text: , and a

text: back light

text: for illumination. Low-key lighting often uses only one key light, optionally controlled with a fill light or a simple

text: reflector

text: The color of the lamps varies by jurisdiction; typical colors are blue and/or red for police, fire, and medical-emergency vehicles; amber for hazards (slow-moving vehicles, wide loads, tow trucks, security personnel, construction vehicles, etc.); green for volunteer firefighters or for medical personnel, and violet for funerary vehicles. Beacons may be constructed with halogen bulbs similar to those used in vehicle headlamps, xenon flashtubes, or LEDs. Incandescent and xenon light sources require the vehicle’s engine to continue running to ensure that the battery is not depleted when the lights are used for a prolonged period. The low power consumption of LEDs allows the vehicle's engine to remain turned off while the lights operate nodes.

text: The color of the lamps varies by jurisdiction; typical colors are blue and/or red for police, fire, and medical-emergency vehicles; amber for hazards (slow-moving vehicles, wide loads, tow trucks, security personnel, construction vehicles, etc.); green for volunteer firefighters or for medical personnel, and violet for funerary vehicles. Beacons may be constructed with

text: halogen bulbs

text: similar to those used in vehicle

text: headlamp

text: s, xenon

text: flashtube

text: s, or

text: LEDs

text: . Incandescent and xenon light sources require the vehicle’s engine to continue running to ensure that the battery is not depleted when the lights are used for a prolonged period. The low power consumption of LEDs allows the vehicle's engine to remain turned off while the lights operate nodes.

text: For the purpose of measuring illumination, the candela is not a practical unit, as it only applies to idealized point light sources, each approximated by a source small compared to the distance from which its luminous radiation is measured, also assuming that it is done so in the absence of other light sources. What gets directly measured by a light meter is incident light on a sensor of finite area, i.e. illuminance in lm/m (lux). However, if designing illumination from many point light sources, like light bulbs, of known approximate omnidirectionally-uniform intensities, the contributions to illuminance from incoherent light being additive, it is mathematically estimated as follows. If r is the position of the i-th source of uniform intensity I, and â is the unit vector normal to the illuminated elemental opaque area dA being measured, and provided that all light sources lie in the same half-space divided by the plane of this area,

text: For the purpose of measuring illumination, the candela is not a practical unit, as it only applies to idealized point light sources, each approximated by a source small compared to the distance from which its luminous radiation is measured, also assuming that it is done so in the absence of other light sources. What gets directly measured by a

text: light meter

text: is incident light on a sensor of finite area, i.e.

text: illuminance

text: in lm/m (lux). However, if designing illumination from many point light sources, like light bulbs, of known approximate omnidirectionally-uniform intensities, the contributions to illuminance from

text: incoherent light

text: being additive, it is mathematically estimated as follows. If r is the position of the i-th source of uniform intensity I, and â is the unit vector

text: normal

text: to the illuminated elemental opaque area dA being measured, and provided that all light sources lie in the same half-space divided by the plane of this area,

text: The chart below lists values of overall luminous efficacy and efficiency for several types of general service, 120-volt, 1000-hour lifespan incandescent bulb, and several idealized light sources. The values for the incandescent bulbs are source efficiencies and efficacies. The values for the ideal sources are radiant efficiencies and efficacies. A similar chart in the article on luminous efficacy compares a broader array of light sources to one another.

text: The chart below lists values of overall luminous efficacy and efficiency for several types of general service, 120-volt, 1000-hour lifespan incandescent bulb, and several idealized light sources. The values for the incandescent bulbs are source efficiencies and efficacies. The values for the ideal sources are radiant efficiencies and efficacies. A similar chart in the article on

text: luminous efficacy

text: compares a broader array of light sources to one another.

text: By far the most recognized type of lighting is the incandescent light bulb using a tungsten filament. These were the first low power electric lights in cities worldwide. Some can still be found in streetlight service, although many of them are using more efficient CFL light bulbs and some have been converted to MV or HPS. Others have been installed popular downtown areas of major cities to have a nostalgia effect. They were introduced some 20 years after open arc lamps, and in many cases replaced the higher maintenance arc lamps. Incandescent light also has excellent CRI rated at 100. Color temperature is generally around 2000–3200 K depending on the type of lamp. An incandescent lamp is less efficient when compared to HID and gas discharge lighting such as Neon light.

text: By far the most recognized type of lighting is the

text: incandescent light bulb

text: using a

text: tungsten

text: filament. These were the first low power electric lights in cities worldwide. Some can still be found in streetlight service, although many of them are using more efficient CFL light bulbs and some have been converted to MV or HPS. Others have been installed popular downtown areas of major cities to have a nostalgia effect. They were introduced some 20 years after open arc lamps, and in many cases replaced the higher maintenance arc lamps.

text: Incandescent light

text: also has excellent

text: CRI

text: rated at 100. Color temperature is generally around 2000–3200

text: K

text: depending on the type of lamp. An incandescent lamp is less efficient when compared to

text: HID

text: and

text: gas discharge

text: lighting such as

text: Neon light

text: The term "solid state" refers commonly to light emitted by solid-state electroluminescence, as opposed to incandescent bulbs (which use thermal radiation) or fluorescent tubes. Compared to incandescent lighting, SSL creates visible light with reduced heat generation and less energy dissipation. Most common "white" LEDs convert blue light from a solid-state device to an (approximate) white light spectrum using photoluminescence, the same principle used in conventional fluorescent tubes.

text: The term "

text: solid state

text: " refers commonly to light emitted by solid-state electroluminescence, as opposed to incandescent bulbs (which use thermal radiation) or fluorescent tubes. Compared to incandescent lighting, SSL creates visible light with reduced heat generation and less energy dissipation. Most common "white" LEDs convert blue light from a solid-state device to an (approximate) white light spectrum using photoluminescence, the same principle used in conventional fluorescent tubes.

text: Many governments list specific requirements for emergency vehicle lighting. These requirements may address the colour, location and intensity/visibility of the lights, and whether they should flash or burn steadily. Laws also may regulate what vehicles may display these lights, and under what circumstances they may do so.

text: One possible explanation for the missing light-source is that illumination from the assumed quasar was a transient phenomenon. In this case, its effects on HsV would be still visible because of the distance of several tens of thousands of light years between HsV and the quasar in the nearby galaxy: HsV would show a "light echo" or "ghost image" of events that are older than those currently seen in the galaxy.

text: One possible explanation for the missing light-source is that illumination from the assumed quasar was a

text: transient phenomenon

text: . In this case, its effects on HsV would be still visible because of the distance of several tens of thousands of

text: light year

text: s between HsV and the

text: quasar

text: in the nearby galaxy: HsV would show a "

text: light echo

text: " or "ghost image" of events that are older than those currently seen in the galaxy.

text: Prior to Köhler illumination critical illumination was the predominant technique for sample illumination. Critical illumination has the major limitation that the image of the light source (typically a light bulb) falls in the same plane as the image of the specimen, i.e. the bulb filament is visible in the final image. The image of the light source is often referred to as the filament image. Critical illumination therefore gives uneven illumination of the sample; bright regions in the filament image illuminate those regions of the sample more strongly. Uneven illumination is undesirable as it can introduce artefacts such as glare and shadowing in the image.

text: Prior to Köhler illumination

text: critical illumination

text: was the predominant technique for sample illumination. Critical illumination has the major limitation that the image of the light source (typically a

text: light bulb

text: ) falls in the same plane as the image of the specimen, i.e. the bulb filament is visible in the final image. The image of the light source is often referred to as the filament image. Critical illumination therefore gives uneven illumination of the sample; bright regions in the filament image illuminate those regions of the sample more strongly. Uneven illumination is undesirable as it can introduce artefacts such as

text: glare

text: and shadowing in the image.

text: A photoelectric, or optical smoke detector contains a source of infrared, visible, or ultraviolet light (typically an incandescent light bulb or light-emitting diode), a lens, and a photoelectric receiver (typically a photodiode). In spot-type detectors all of these components are arranged inside a chamber where air, which may contain smoke from a nearby fire, flows. In large open areas such as atria and auditoriums, optical beam or projected-beam smoke detectors are used instead of a chamber within the unit: a wall-mounted unit emits a beam of infrared or ultraviolet light which is either received and processed by a separate device, or reflected back to the receiver by a reflector. In some types, particularly optical beam types, the light emitted by the light source passes through the air being tested and reaches the photosensor. The received light intensity will be reduced by absorption due to smoke, air-borne dust, or other substances; the circuitry detects the light intensity and generates the alarm if it is below a specified threshold, potentially due to smoke. In other types, typically chamber types, the light is not directed at the sensor, which is not illuminated in the absence of particles. If the air in the chamber contains particles (smoke or dust), the light is scattered and some of it reaches the sensor, triggering the alarm.

text: A photoelectric, or optical smoke detector contains a source of infrared, visible, or ultraviolet light (typically an

text: incandescent light bulb

text: or

text: light-emitting diode

text: ), a

text: lens

text: , and a photoelectric receiver (typically a

text: photodiode

text: ). In spot-type detectors all of these components are arranged inside a chamber where air, which may contain smoke from a nearby fire, flows. In large open areas such as atria and auditoriums,

text: optical beam

text: or projected-beam smoke detectors are used instead of a chamber within the unit: a wall-mounted unit emits a beam of infrared or ultraviolet light which is either received and processed by a separate device, or reflected back to the receiver by a reflector. In some types, particularly optical beam types, the light emitted by the light source passes through the air being tested and reaches the photosensor. The received

text: light intensity will be reduced

text: by

text: absorption

text: due to smoke, air-borne dust, or other substances; the circuitry detects the light intensity and generates the alarm if it is below a specified threshold, potentially due to smoke. In other types, typically chamber types, the light is not directed at the sensor, which is not illuminated in the absence of particles. If the air in the chamber contains particles (smoke or dust), the light is

text: scattered

text: and some of it reaches the sensor, triggering the alarm.

text: The resulting light was not visible from the northern approach to Jervis Bay, and was barely visible from the southern approach. When inspected by members of the Pilots Board it was found that on top of the inaccuracies, the contractor built the light  north of the intended site, as it was closer to the quarry he was obtaining the stone from.

text: Light levels need to be measured when the exhibition is prepared. UV light meters will check radiation levels in an exhibit space, and data event loggers help determine visible light levels over an extended period of time. Blue wool standards cards can also be utilized to predict the extent to which materials will be damaged during exhibits. UV radiation must be eliminated to the extent it is physically possible; it is recommended that light with a wavelength below 400 nm (ultraviolet radiation) be limited to no more than 75 microwatts per lumen at 10 to 100 lux. Furthermore, exposure to natural light is undesirable because of its intensity and high UV content. When such exposure is unavoidable, preventative measures must be taken to control UV radiation, including the use of blinds, shades, curtains, UV filtering films, and UV-filtering panels in windows or cases. Artificial light sources are safer options for exhibition. Among these sources, incandescent lamps are most suitable because they emit little or no UV radiation.  Fluorescent lamps, common in most institutions, may be used only when they produce a low UV output and when covered with plastic sleeves before exhibition.  Though tungsten-halogen lamps are currently a favorite artificial lighting source, they still give off significant amounts of UV radiation; use these only with special UV filters and dimmers.  Lights should be lowered or turned off completely when visitors are not in the exhibition space.

text: Light levels need to be measured when the exhibition is prepared.

text: UV

text: light meters will check radiation levels in an exhibit space, and data event loggers help determine visible light levels over an extended period of time. Blue wool standards cards can also be utilized to predict the extent to which materials will be damaged during exhibits. UV

text: radiation

text: must be eliminated to the extent it is physically possible; it is recommended that light with a wavelength below 400

text: nm

text: (ultraviolet radiation) be limited to no more than 75

text: microwatts

text: per

text: lumen

text: at 10 to 100 lux. Furthermore, exposure to

text: natural light

text: is undesirable because of its intensity and high UV content. When such exposure is unavoidable, preventative measures must be taken to control UV radiation, including the use of blinds, shades, curtains,

text: UV filter

text: ing films, and UV-filtering panels in windows or cases.

text: Artificial light

text: sources are safer options for exhibition. Among these sources,

text: incandescent lamps

text: are most suitable because they emit little or no UV radiation.

text: Fluorescent lamp

text: s, common in most institutions, may be used only when they produce a low UV output and when covered with plastic sleeves before exhibition.  Though

text: tungsten-halogen lamps

text: are currently a favorite artificial lighting source, they still give off significant amounts of UV radiation; use these only with special UV filters and dimmers.  Lights should be lowered or turned off completely when visitors are not in the exhibition space.

text: The instrumentation involved for pc-AFM is very similar to that necessary for traditional AFM or the modified conductive AFM. The main difference between pc-AFM and other types of AFM instruments is the illumination source that is focused through the inverted microscope objective and the neutral density filter that is positioned adjacent to the illumination source. The technical parameters of pc-AFM are identical to those of traditional AFM techniques. This section will focus on the instrumentation necessary for AFM and then detail the requirements for pc-AFM modification. The main instrumental components to all AFM techniques are the conductive AFM cantilever and tip, the modified piezo components and the sample substrate. The components for photoconductive modification include: the illumination source (532 nm laser), filter and inverted microscope. When modifying traditional AFM for pc application, all components must be combined such that they do not interfere with one another and so that various sources of noise and mechanical interference do not disrupt the optical components.

text: The instrumentation involved for pc-AFM is very similar to that necessary for traditional AFM or the modified conductive AFM. The main difference between pc-AFM and other types of AFM instruments is the illumination source that is focused through the inverted

text: microscope objective

text: and the

text: neutral density filter

text: that is positioned adjacent to the illumination source. The technical parameters of pc-AFM are identical to those of traditional AFM techniques. This section will focus on the instrumentation necessary for AFM and then detail the requirements for pc-AFM modification. The main instrumental components to all AFM techniques are the conductive AFM cantilever and tip, the modified

text: piezo

text: components and the sample substrate. The components for photoconductive modification include: the illumination source (532 nm laser), filter and inverted microscope. When modifying traditional AFM for pc application, all components must be combined such that they do not interfere with one another and so that various sources of noise and mechanical interference do not disrupt the optical components.

text: The current structure, installed on 26 March 1990,  is a white fibre glass hut, mounted on a small stainless steel structure, on concrete piles. It is  tall, from seabed to the deck, and the light is displayed at , with a daymark at .The current light characteristic is a flash every five seconds, white, red or green, depending on direction (Fl.W.R.G. 5s). Green is displayed at 84°-97°, visible for , white is displayed at 97°-126° and 229°-84°, visible for , and red is displayed at 126°-229°, visible for .The light source is a solar powered ML-300 beacon with a 12 Volt 35 Watt Halogen lamp, showing an intensity of 2,100 cd for the white light and 420 cd for the red and green ones. It is operated by the Australian Maritime Safety Authority.

text: The current structure, installed on 26 March 1990,  is a white fibre glass hut, mounted on a small

text: stainless steel

text: structure, on concrete piles. It is  tall, from seabed to the deck, and the light is displayed at , with a

text: daymark

text: at .The current

text: light characteristic

text: is a flash every five seconds, white, red or green, depending on direction (Fl.W.R.G. 5s). Green is displayed at 84°-97°, visible for , white is displayed at 97°-126° and 229°-84°, visible for , and red is displayed at 126°-229°, visible for .The light source is a

text: solar power

text: ed ML-300 beacon with a 12

text: Volt

text: Watt

text: Halogen lamp

text: , showing an intensity of 2,100

text: cd

text: for the white light and 420 cd for the red and green ones. It is operated by the

text: Australian Maritime Safety Authority

text: UV-visible spectroscopy of microscopic samples is done by integrating an optical microscope with UV-visible optics, white light sources, a monochromator, and a sensitive detector such as a charge-coupled device (CCD) or photomultiplier tube (PMT). As only a single optical path is available, these are single beam instruments. Modern instruments are capable of measuring UV-visible spectra in both reflectance and transmission of micron-scale sampling areas. The advantages of using such instruments is that they are able to measure microscopic samples but are also able to measure the spectra of larger samples with high spatial resolution. As such, they are used in the forensic laboratory to analyze the dyes and pigments in individual textile fibers, microscopic paint chips  and the color of glass fragments. They are also used in materials science and biological research and for determining the energy content of coal and petroleum source rock by measuring the vitrinite reflectance. Microspectrophotometers are used in the semiconductor and micro-optics industries for monitoring the thickness of thin films after they have been deposited. In the semiconductor industry, they are used because the critical dimensions of circuitry is microscopic. A typical test of a semiconductor wafer would entail the acquisition of spectra from many points on a patterned or unpatterned wafer. The thickness of the deposited films may be calculated from the interference pattern of the spectra. In addition, ultraviolet-visible spectrophotometry can be used to determine the thickness, along with the refractive index and extinction coefficient of thin films as described in Refractive index and extinction coefficient of thin film materials. A map of the film thickness across the entire wafer can then be generated and used for quality control purposes.

text: UV-visible spectroscopy of microscopic samples is done by integrating an optical microscope with UV-visible optics, white light sources, a

text: monochromator

text: , and a sensitive detector such as a

text: charge-coupled device

text: (CCD) or

text: photomultiplier

text: tube (PMT). As only a single optical path is available, these are single beam instruments. Modern instruments are capable of measuring UV-visible spectra in both reflectance and transmission of micron-scale sampling areas. The advantages of using such instruments is that they are able to measure microscopic samples but are also able to measure the spectra of larger samples with high spatial resolution. As such, they are used in the forensic laboratory to analyze the dyes and pigments in individual textile fibers, microscopic paint chips  and the color of glass fragments. They are also used in materials science and biological research and for determining the energy content of coal and petroleum source rock by measuring the

text: vitrinite

text: reflectance. Microspectrophotometers are used in the semiconductor and micro-optics industries for monitoring the thickness of thin films after they have been deposited. In the semiconductor industry, they are used because the critical dimensions of circuitry is microscopic. A typical test of a semiconductor wafer would entail the acquisition of spectra from many points on a patterned or unpatterned wafer. The thickness of the deposited films may be calculated from the

text: interference pattern

text: of the spectra. In addition, ultraviolet-visible spectrophotometry can be used to determine the thickness, along with the refractive index and extinction coefficient of thin films as described in

entity_name: Refractive index and extinction coefficient of thin film materials

text: Refractive index and extinction coefficient of thin film materials

text: . A map of the film thickness across the entire wafer can then be generated and used for quality control purposes.

text: The above description covers a wider class of concentrators (for example simple optical concentrators) than just luminescent solar concentrators. The essential attribute of LSCs is that they incorporate luminescent materials that absorb incoming light with a wide frequency range, and re-emit the energy in the form of light in a narrow frequency range. The narrower the frequency range, (i.e. the higher the saturation) the simpler a photovoltaic cell can be designed to convert it to electricity.

text: The above description covers a wider class of concentrators (for example simple optical concentrators) than just luminescent solar concentrators. The essential attribute of LSCs is that they incorporate luminescent materials that absorb incoming light with a wide frequency range, and re-emit the energy in the form of light in a narrow frequency range. The narrower the frequency range, (i.e. the higher the saturation) the simpler a

text: photovoltaic

text: cell

text: can be designed to convert it to electricity.

text: Luminous paint or luminescent paint is paint that exhibits luminescence. In other words, it gives off visible light through fluorescence, phosphorescence, or radioluminescence.

text: Luminous paint or luminescent paint is

text: paint

text: that exhibits

text: luminescence

text: . In other words, it gives off

text: visible

text: light

text: through

text: fluorescence

text: phosphorescence

text: , or

text: radioluminescence

text: When light strikes an object, it usually has not just a single frequency (or wavelength) but many. Objects have a tendency to selectively absorb, reflect or transmit light of certain frequencies. That is, one object might reflect green light while absorbing all other frequencies of visible light. Another object might selectively transmit blue light while absorbing all other frequencies of visible light. The manner in which visible light interacts with an object is dependent upon the frequency of the light, the nature of the atoms in the object, and often the nature of the electrons in the atoms of the object.

text: When light strikes an object, it usually has not just a single frequency (or wavelength) but many. Objects have a tendency to selectively absorb, reflect or transmit light of certain frequencies. That is, one object might reflect green light while absorbing all other frequencies of visible light. Another object might selectively transmit blue light while absorbing all other frequencies of visible light. The manner in which visible light interacts with an object is dependent upon the frequency of the light, the nature of the atoms in the object, and often the nature of the

text: electron

text: s in the

text: atom

text: s of the object.

text: Incandescence is the emission of electromagnetic radiation (including visible light) from a hot body as a result of its temperature.  The term derives from the Latin verb incandescere, to glow white.

text: Incandescence is the emission of

text: electromagnetic radiation

text: (including visible

text: light

text: ) from a hot body as a result of its temperature.  The term derives from the Latin verb incandescere, to glow white.

text: Sunglasses offer protection against excessive exposure to light, including its visible and invisible components.

text: Bioluminescence refers to the ability of certain living things in the environment to produce light by the action of enzymes. Bioluminescent fungi are widespread, and over 70 species are known. Although the intensity of their luminescence is generally low compared to many other bioluminescent organisms, fungi glow continuously for days, so their total emission is comparable with that of most brightly luminescent organisms, such as fireflies. Luminous fungi are found growing on decaying wood, leading to the popular name of "foxfire" or "glow wood" when their glow is visible at night. The responsible oxidative enzymes—known generically as luciferases—produce light by oxidizing a pigment called a luciferin. In some areas, P. stypticus is bioluminescent, and the fruit bodies of these strains will glow in the dark when fresh or sometimes when revived in water after drying.

text: Bioluminescence

text: refers to the ability of certain living things in the environment to produce light by the action of

text: enzyme

text: s. Bioluminescent fungi are widespread, and over 70 species are known. Although the intensity of their luminescence is generally low compared to many other bioluminescent organisms, fungi glow continuously for days, so their total emission is comparable with that of most brightly luminescent organisms, such as

text: fireflies

text: . Luminous fungi are found growing on decaying wood, leading to the popular name of "

text: foxfire

text: " or "glow wood" when their glow is visible at night. The responsible

text: oxidative enzyme

text: s—known generically as

text: luciferase

text: s—produce light by

text: oxidizing

text: a

text: pigment

text: called a

text: luciferin

text: . In some areas, P. stypticus is bioluminescent, and the fruit bodies of these strains will glow in the dark when fresh or sometimes when revived in water after drying.

text: The water-solubility of the organic constituent of the absorber material make devices highly prone to rapid degradation in moist environments. The degradation which is caused by moisture can be reduced by optimizing the constituent materials, the architecture of the cell, the interfaces and the environment conditions during the fabrication steps.  Encapsulating the perovskite absorber with a composite of carbon nanotubes and an inert polymer matrix has been demonstrated to successfully prevent the immediate degradation of the material when exposed to moist ambient air at elevated temperatures. However, no long term studies and comprehensive encapsulation techniques have yet been demonstrated for perovskite solar cells. Beside moisture instability, it has also been shown that the embodiment of devices in which a mesoporous TiO layer is sensitized with the perovskite absorber exhibits UV light induced instability. The cause for the observed decline in device performance of those solar cells is linked to the interaction between photogenerated holes inside the TiO and oxygen radicals on the surface of TiO.The measured ultra low thermal conductivity of 0.5 W/(Km) at room temperature in CHNHPbI can prevent fast propagation of the light deposited heat, and keep the cell resistive on thermal stresses that can reduce its life time. The PbI residue in perovskite film has been experimentally demonstrated to have a negative effect on the long-term stability of devices. The stabilization problem is claimed to be solved by replacing the organic transport layer with a metal oxide layer, allowing the cell to retain 90% capacity after 60 days. Besides, the two instabilities issues can be solved by using multifunctional fluorinated photopolymer coatings that confer luminescent and easy-cleaning features on the front side of the devices, while concurrently forming a strongly hydrophobic barrier toward environmental moisture on the back contact side. The front coating can prevent the UV light of the whole incident solar spectrum from negatively interacting with the PSC stack by converting it into visible light, and the back layer can prevent water from permeation within the solar cell stack. The resulting devices demonstrated excellent stability in terms of power conversion efficiencies during a 180-day aging test in the lab and a real outdoor condition test for more than 3 months.

text: The water-solubility of the organic constituent of the absorber material make devices highly prone to rapid degradation in moist environments. The degradation which is caused by moisture can be reduced by optimizing the constituent materials, the architecture of the cell, the interfaces and the environment conditions during the fabrication steps.  Encapsulating the perovskite absorber with a composite of

text: carbon nanotube

text: s and an inert polymer matrix has been demonstrated to successfully prevent the immediate degradation of the material when exposed to moist ambient air at elevated temperatures. However, no long term studies and comprehensive encapsulation techniques have yet been demonstrated for perovskite solar cells. Beside moisture instability, it has also been shown that the embodiment of devices in which a mesoporous TiO layer is sensitized with the perovskite absorber exhibits

text: UV light

text: induced instability. The cause for the observed decline in device performance of those solar cells is linked to the interaction between photogenerated holes inside the TiO and

text: oxygen radicals

text: The relationships between the energies of the various quantum states are treated by atomic orbital, molecular orbital, and Ligand Field Theory. If photons of a particular wavelength are absorbed by matter, then when we observe light reflected from or transmitted through that matter, what we see is the complementary color, made up of the other visible wavelengths remaining. For example, beta-carotene has maximum absorption at 454 nm (blue light), consequently what visible light remains appears orange .

text: The relationships between the energies of the various quantum states are treated by

text: atomic orbital

text: molecular orbital

text: , and

text: Ligand Field Theory

text: . If photons of a particular wavelength are absorbed by matter, then when we observe light reflected from or transmitted through that matter, what we see is the

text: complementary color

text: , made up of the other visible wavelengths remaining. For example,

text: beta-carotene

text: has maximum absorption at 454 nm (blue light), consequently what visible light remains appears orange .

text: Exposure and focusing are difficult when using UV or IR film with a camera and lens designed for visible light. The ISO standard for film speed only applies to visible light, so visual-spectrum light meters are nearly useless. Film manufacturers can supply suggested equivalent film speeds under different conditions, and recommend heavy bracketing (e.g., with a certain filter, assume ISO 25 under daylight and ISO 64 under tungsten lighting). This allows a light meter to be used to estimate an exposure. The focal point for IR is slightly farther away from the camera than visible light, and UV slightly closer; this must be compensated for when focusing. Apochromatic lenses are sometimes recommended due to their improved focusing across the spectrum.

text: Exposure and focusing are difficult when using UV or IR film with a camera and lens designed for visible light. The ISO standard for film speed only applies to visible light, so visual-spectrum light meters are nearly useless. Film manufacturers can supply suggested equivalent film speeds under different conditions, and recommend heavy

text: bracketing

text: (e.g., with a certain filter, assume ISO 25 under daylight and ISO 64 under tungsten lighting). This allows a light meter to be used to estimate an exposure. The focal point for IR is slightly farther away from the camera than visible light, and UV slightly closer; this must be compensated for when focusing.

text: Apochromat

text: ic lenses are sometimes recommended due to their improved focusing across the spectrum.

text: Ambassadors now came with a unique compound curved windshield that cut into the roof. This improved visibility, did away with the “knee knocker” dogleg design of AMC's first generation wrap-around windshield, and resulted in an even stiffer unitized structure. The 1960 Ambassador had a low cowl which with the compound windshield afforded excellent visibility. The Ambassador was offered in higher end Custom or entry level Super trim levels. All 1960 Ambassadors came with a new instrument cluster under a padded cowl, as well as illuminated controls for lights, wipers, fan, and defrost functions. The 1960 Ambassadors continued with an enclosed drive shaft (torque tube) and coil springs at all four corners, although the suspension was revised resulting in better handling. The top-of-the-line Ambassador models came standard with individual "airliner" reclining front seats that now had even more luxurious fabrics than in previous years.

text: Cyanoacrylate is used as a forensic tool to capture latent fingerprints on non-porous surfaces like glass, plastic, etc. Cyanoacrylate is warmed to produce fumes which react with the invisible fingerprint residues and atmospheric moisture to form a white polymer (polycyanoacrylate) on the fingerprint ridges.  The ridges can then be recorded. The developed fingerprints are, on most surfaces (except on white plastic or similar), visible to the naked eye. Invisible or poorly visible prints can be further enhanced by applying a luminescent or non-luminescent stain.

text: Cyanoacrylate is used as a

text: forensic

text: tool to capture

text: latent fingerprint

text: s on non-porous surfaces like glass, plastic, etc. Cyanoacrylate is warmed to produce fumes which react with the invisible fingerprint residues and atmospheric moisture to form a white polymer (polycyanoacrylate) on the fingerprint ridges.  The ridges can then be recorded. The developed fingerprints are, on most surfaces (except on white plastic or similar), visible to the naked eye. Invisible or poorly visible prints can be further enhanced by applying a luminescent or non-luminescent stain.

text: In architecture, light reflectance value (LRV), is a measure of visible and usable light that is reflected from a surface when illuminated by a light source.  The measurement is most commonly used by design professionals, such as architectural color consultants, architects, environmental graphic designers and interior designers.

text: In

text: architecture

text: , light reflectance value (LRV), is a measure of visible and usable light that is

text: reflected

text: from a surface when illuminated by a light source.  The measurement is most commonly used by design professionals, such as architectural

text: color consultants

text: architect

text: s,

text: environmental graphic designers

text: and

text: interior designer

text: s.

text: Incandescent miniatures now usually come in sets of 50 or 100 (which contains two circuits of 50) 2.5 V 170 mA bulbs, though decorative sets with larger bulbs (C6 or pearl style) typically come in sets of 35 or 70.  Several "extra-bright" sets also use 70 or 105 bulbs, keeping the per-bulb voltage at 3.5 instead of 2.5.

text: Incandescent miniatures now usually come in sets of 50 or 100 (which contains two circuits of 50) 2.5 V 170 mA bulbs, though decorative sets with larger bulbs (C6 or pearl style) typically come in sets of 35 or 70.  Several "extra-bright" sets also use 70 or 105 bulbs, keeping the

text: per-bulb voltage

text: at 3.5 instead of 2.5.

text: Light is the core concept in Iranian mysticism. The main roots of this thought is in the Zoroastrian beliefs, which defines The supreme God Ahura Mazda as the source of light. This very essential attribute is manifested in various schools of thought in the Iranian Religions and philosophy. Later this notion has been dispensed into the whole Middle East, having a great effect of shaping the paradigms of different religions and philosophies emerging one after another in the region. After the Arab invasion, this concept has been incorporated into the Islamic teachings by Iranian thinkers, most famous of them Shahab al-Din Suhrawardi, who is the founder of the illumination philosophy.

text: Light is the core concept in Iranian mysticism. The main roots of this thought is in the

text: Zoroastrian

text: beliefs, which defines The supreme God

text: Ahura Mazda

text: as the source of light. This very essential attribute is manifested in various schools of thought in the

text: Iranian Religions

text: and philosophy. Later this notion has been dispensed into the whole

text: Middle East

text: , having a great effect of shaping the paradigms of different religions and philosophies emerging one after another in the region. After the

text: Arab invasion

text: , this concept has been incorporated into the Islamic teachings by Iranian thinkers, most famous of them

entity_name: Shahab al-Din Yahya ibn Habash Suhrawardi

text: Shahab al-Din Suhrawardi

text: , who is the founder of the

text: illumination philosophy

text: MORIS (MIT Optical Rapid Imaging System) s a high-speed, visible-wavelength camera for use on IRTF using an electron multiplying CCD.  MORIS is mounted on the side window of SpeX, and is fed by the internal cold dichroic in SpeX. The design is based on POETS (Portable Occultation, Eclipse, and Transit Systems), which were developed by a collaboration between MIT and Williams College.  MORIS is available for open use on IRTF and its user interface has been converted to the IRTF standard interface.  In addition to visible light photometry, MORIS is also used as a visible light guider for SpeX, allowing guiding on targets as faint as V=20.  The guiding software includes atmospheric dispersion correction to move the visible light guide box to keep the IR image on the SpeX slit.

text: An important area of ergonomics concerns lighting, so that the user can see easily any possible fall hazards (such as steps or obstacles), and so avoid them. Lamps and lighting, for example, should be of great intensity or power (or illuminance) so that dangers are clearly illuminated and can be seen by users. They should also react quickly when switched on, so many CFLs are or should be excluded. Incandescent bulbs  normally offer extremely fast reaction times as well as high intensity illumination, while CFLs take time to warm up to maximum illuminance. It is especially vital for older people who may be suffering from macular degeneration or cataracts leading to poor eyesight. The stability of the user is essential for stable movement, and his or her balance can be improved by, for example, high friction floors to prevent slippage. Footwear such as shoes should also have high friction natural rubber or synthetic rubber soles, preferably serrated as in the Vibram sole so as to give extra grip.

text: An important area of

text: ergonomics

text: concerns

text: lighting

text: , so that the user can see easily any possible fall hazards (such as steps or obstacles), and so avoid them.

text: Lamps

text: and

text: lighting

text: , for example, should be of great intensity or power (or

text: illuminance

text: ) so that dangers are clearly illuminated and can be seen by users. They should also react quickly when switched on, so many

text: CFL

text: s are or should be excluded.

text: Incandescent bulb

text: s  normally offer extremely fast reaction times as well as high intensity illumination, while CFLs take time to warm up to maximum illuminance. It is especially vital for older people who may be suffering from

text: macular degeneration

text: or

text: cataracts

text: leading to poor eyesight. The stability of the user is essential for stable movement, and his or her balance can be improved by, for example, high

text: friction

text: floors to prevent slippage.

text: Footwear

text: such as

text: shoe

text: s should also have high friction

text: natural rubber

text: or

text: synthetic rubber

text: soles, preferably serrated as in the

text: Vibram

text: sole so as to give extra grip.

text: Incandescent light bulbs use a tungsten filament heated to high temperature to produce visible light and, necessarily, even more infrared radiation.  Round bulbs, often tinted red to reduce visible light, provide infrared radiant heat suitable for warming of people or animals, but the power density available is low. The development of quartz halogen linear lamps allowed much higher power density up to 200 watts/inch of lamp (8 w/mm), useful for industrial heating, drying and processing applications.By adjusting the voltage applied to incandescent lamps, the spectrum of the radiated energy can be made to reduce visible light and emphasize infrared energy production. Different wavelengths of infrared radiation are differently absorbed by different materials.

text: Incandescent light bulb

text: s use a

text: tungsten

text: filament heated to high temperature to produce visible light and, necessarily, even more infrared radiation.  Round bulbs, often tinted red to reduce visible light, provide infrared radiant heat suitable for warming of people or animals, but the power density available is low. The development of quartz halogen linear lamps allowed much higher power density up to 200 watts/inch of lamp (8 w/mm), useful for industrial heating, drying and processing applications.By adjusting the voltage applied to incandescent lamps, the spectrum of the radiated energy can be made to reduce visible light and emphasize infrared energy production. Different wavelengths of infrared radiation are differently absorbed by different materials.

text: A chandelier  is a decorative ceiling-mounted light fixture, a distinct type of pendant light.  Chandeliers are often ornate, and normally use incandescent light bulbs, though some modern designs also use fluorescent lamps or even LEDs. Crystal chandeliers have more or less complex arrays of crystal prisms to illuminate a room with refracted light. Chandeliers are often located in hallways, living rooms, dining rooms, and recently in bathrooms and bedrooms.

text: A chandelier  is a decorative ceiling-mounted

text: light fixture

text: , a distinct type of

text: pendant light

text: .  Chandeliers are often ornate, and normally use

text: incandescent light bulb

text: s, though some modern designs also use

text: fluorescent lamps

text: or even

text: LED

text: s. Crystal chandeliers have more or less complex arrays of crystal prisms to illuminate a room with

text: refracted

text: light. Chandeliers are often located in hallways, living rooms, dining rooms, and recently in bathrooms and bedrooms.

text: Theoria is beyond conceptual knowledge. It is the state in which the mind is placed in the heart (kardio) and the nous is focused on the immediacy or immanence of the Trinity of God rather than strictly insight or foresight (which is to face the unknown with free will and faith) and rather than hindsight (determinism and knowledge). It is much like the difference between reading about the experience of another and reading about one's own experience. Thus, theoria is an expression of insight (noesis), and is deeply focused on the 'now', the 'immediate', and the 'present'. Though theoria is akin to acting by free will and by conscious choice rather than deterministically, it holds that one moves through time into the future without knowing, but proceeds by faith (faith is meta-gnosis or beyond knowledge). Theoria means placing the actual experience above the recollection of an experience (mnemonic) or memory. As it is the contemplation of the present (insight) while in the present, rather than the past (knowledge) or future (unknown), it is ultimately the experience of the hypostases of God. In other words, theoria places primacy of experience and observation over a speculative, discursive, rational analysis (Orthodox Empirical theology). This illumination is photismos, a light that permeates all things and is without source, a light that illuminates not only the physical world, but also the darkness within humanity; this light is also called the Tabor light. The Trinity is the three realities of the single God at once. Each reality or hypostasis is critical to the ontology of being (ousia).

text: Theoria is beyond conceptual knowledge. It is the state in which the mind is placed in the heart (

text: kardio

text: ) and the

text: nous

text: is focused on the

text: immediacy

text: or

text: immanence

text: of the Trinity of God rather than strictly

text: insight

text: or

text: foresight

text: (which is to face the unknown with

text: free will

text: and

text: faith

text: ) and rather than

text: hindsight

text: determinism

text: and knowledge). It is much like the difference between reading about the experience of another and reading about one's own experience. Thus, theoria is an expression of insight (noesis), and is deeply focused on the 'now', the 'immediate', and the 'present'. Though theoria is akin to acting by

text: free will

text: and by conscious choice rather than deterministically, it holds that one moves through time into the future without knowing, but proceeds by faith (faith is meta-gnosis or beyond knowledge). Theoria means placing the actual experience above the recollection of an experience (

text: mnemonic

text: ) or memory. As it is the contemplation of the present (

text: insight

text: ) while in the present, rather than the past (knowledge) or future (unknown), it is ultimately the experience of the hypostases of God. In other words, theoria places primacy of experience and observation over a speculative,

text: discursive

text: , rational analysis (Orthodox

text: Empirical

text: theology). This illumination is

text: photismos

text: , a light that permeates all things and is without source, a light that illuminates not only the physical world, but also the darkness within humanity; this light is also called the

text: Tabor light

text: . The Trinity is the three realities of the single God at once. Each reality or hypostasis is critical to the ontology of being (ousia).

text: A metal-halide lamp is an electric lamp that produces light by an electric arc through a gaseous mixture of vaporized mercury and metal halides (compounds of metals with bromine or iodine). It is a type of high-intensity discharge (HID) gas discharge lamp.   Developed in the 1960s, they are similar to mercury vapor lamps, but contain additional metal halide compounds in the quartz arc tube,  which improve the efficiency and color rendition of the light.The most common metal halide compound used is sodium iodide. Once the arc tube reaches its running temperature, the sodium dissociates from the iodine, adding orange and reds to the lamp's spectrum from the sodium D line as the metal ionizes.As a result, metal-halide lamps have high luminous efficacy of around 75–100 lumens per watt, which is about twice that of mercury vapor lights and 3 to 5 times that of incandescent lights and produce an intense white light.    Lamp life is 6,000 to 15,000 hours.   As one of the most efficient sources of high CRI white light, metal halides  were the fastest growing segment of the lighting industry.     They are used for wide area overhead lighting of commercial, industrial, and public spaces, such as parking lots, sports arenas, factories, and retail stores, as well as residential security lighting and automotive headlamps (xenon headlights).

text: A metal-halide lamp is an electric lamp that produces light by an

text: electric arc

text: through a gaseous mixture of vaporized

text: mercury

text: and

text: metal halides

text: (compounds of metals with

text: bromine

text: or

text: iodine

text: ). It is a type of

text: high-intensity discharge

text: (HID)

text: gas discharge lamp

text: .   Developed in the 1960s, they are similar to

text: mercury vapor lamp

text: s, but contain additional metal halide compounds in the

text: quartz

text: arc tube,  which improve the efficiency and

text: color rendition

text: of the light.The most common metal halide compound used is

text: sodium iodide

text: . Once the arc tube reaches its running temperature, the sodium dissociates from the iodine, adding orange and reds to the lamp's spectrum from the sodium D line as the metal ionizes.As a result, metal-halide lamps have high

text: luminous efficacy

text: of around 75–100 lumens per watt, which is about twice that of mercury vapor lights and 3 to 5 times that of

text: incandescent light

text: s and produce an intense white light.    Lamp life is 6,000 to 15,000 hours.   As one of the most efficient sources of high

text: CRI

text: white light, metal halides  were the fastest growing segment of the lighting industry.     They are used for wide area overhead lighting of commercial, industrial, and public spaces, such as parking lots, sports arenas, factories, and retail stores, as well as residential

text: security lighting

text: and

text: automotive headlamp

text: s (

text: xenon headlights

text: However, CRI is a poor indicator of the perception of light produced by LEDs, and scores as low as 25 can produce vivid-appearing white light, while high-scoring sources can still be very poor at rendering reds, including skin tones. This is because CRI is not an indication of light colour, but a measurement of a light source's ability to accurately illuminate different colors compared to a radiating black body light source of the same light color, such as the sun or an incandescent light. The "warmer" light colors, such as a 2700K incandescent bulb or a 1700K candle light are more easily reproduced than more neutral white lights, such as 4800K direct sunlight, and thus usually have higher CRI ratings in alternative light sources such as CFL and LED bulbs; "warmer" light (more red) naturally renders colors less accurately. Think of how the world looks at sunset (2000K) compared to high noon (5600K).

text: The lantern as a source of illumination in art was widely used by Baroque artists, and perfected by Caravaggio. Traditionally a dramatic light source and the resultant chiaroscuro were used as metaphors for the presence of God. Illumination by torch or candlelight took on religious connotations; but in The Third of May the lantern manifests no such miracle. Rather, it affords light only so that the firing squad may complete its grim work, and provides a stark illumination so that the viewer may bear witness to wanton violence. The traditional role of light in art as a conduit for the spiritual has been subverted.

text: The lantern as a source of illumination in art was widely used by

text: Baroque

text: artists, and perfected by

text: Caravaggio

text: . Traditionally a dramatic light source and the resultant chiaroscuro were used as metaphors for the presence of God. Illumination by torch or candlelight took on religious connotations; but in The Third of May the lantern manifests no such miracle. Rather, it affords light only so that the firing squad may complete its grim work, and provides a stark illumination so that the viewer may bear witness to wanton violence. The traditional role of light in art as a

text: conduit

text: for the spiritual has been subverted.

text: The building was dubbed by then De La Salle University System president, Br. Armin Luistro FSC as the "jewel in the crown of the De La Salle University System schools," as well as one of De La Salle's most ambitious projects. The building features an architectural design never before used, with a sophisticated façade and all-glass backside and designed in a way that only floor from the tenth are visible. Calma relates that the building will feature louvers which, when illuminated at night, will appear like lanterns and considering the location, the lighting effects would set the building apart from its surroundings.

text: The building was dubbed by then De La Salle University System president,

text: Br. Armin Luistro FSC

text: as the "jewel in the crown of the De La Salle University System schools," as well as one of De La Salle's most ambitious projects. The building features an architectural design never before used, with a sophisticated façade and all-glass backside and designed in a way that only floor from the tenth are visible. Calma relates that the building will feature louvers which, when illuminated at night, will appear like lanterns and considering the location, the lighting effects would set the building apart from its surroundings.

text: Illumination Software Creator (Illumination) is a tool for visually designing and developing software, and a corresponding Visual programming language that is available for Microsoft Windows, Linux and Mac OS X. Software developed with Illumination runs on Microsoft Windows, Linux, Mac OS X, Android, iOS, Maemo, and Adobe Flash-powered websites. Illumination is developed and sold by Bryan Lunduke. Source code is also available to buy under three levels of licensing.

text: Illumination Software Creator (Illumination) is a tool for visually designing and developing software, and a corresponding

text: Visual programming language

text: that is available for

text: Microsoft Windows

text: Linux

text: and

text: Mac OS X

text: . Software developed with Illumination runs on

text: Microsoft Windows

text: Linux

text: Mac OS X

text: Android

text: iOS

text: Maemo

text: , and

text: Adobe Flash

text: -powered websites. Illumination is developed and sold by

text: Bryan Lunduke

text: Source code

text: is also available to buy under three levels of

text: licensing

text: For an accurate estimate of direct illumination, a ray is traced from the point of intersection to each light source.  As long as a ray does not intersect another object, the light source is used to calculate the direct illumination.  For an approximate estimate of indirect illumination, the photon map is used to calculate the radiance contribution.

text: Some artificial light sources are marketed which have a spectrum similar to that of sunlight, at least in the human visible spectrum range, as well as low flicker. Their spectrum can be made to vary dynamically such as to mimick the changes of natural light over the day. Manufacturers and vendors of such light sources claim that their products can provide the same or similar health effects as natural light. When considered as alternatives to solar light pipes, such products may have lower installation costs but do consume energy during use; therefore they may well be more wasteful in terms of overall energy resources and costs.

text: Some artificial light sources are marketed which have a spectrum similar to that of sunlight, at least in the

text: human visible spectrum

text: range, as well as low flicker. Their spectrum can be made to vary dynamically such as to mimick the changes of natural light over the day. Manufacturers and vendors of such light sources claim that their products can provide the same or similar health effects as natural light. When considered as alternatives to solar light pipes, such products may have lower installation costs but do consume energy during use; therefore they may well be more wasteful in terms of overall energy resources and costs.

text: One of four surviving Bruegel paintings in distemper, the work is a tüchlein, a type of light painting that uses tempera made from pigment mixed with water-soluble glue. This medium was widely used in painting and manuscript illumination before the advent of oil paint.  It is not known from whom Bruegel learnt its use, but amongst those speculated are his mother-in-law, illuminator Mayken Verhulst; his teacher Pieter Coecke van Aelst; and painter and illuminator Giulio Clovio, with whom he resided in Italy and whom he helped paint miniatures in distemper. Due to the high perishability of linen cloth and the solubility of hide glue, tüchleins do not preserve well and are difficult to restore.  The Blind Leading the Blind is in good condition and has suffered no more than some erosion, such as of a herdsman and some fowl in the middle ground.  The grain of the linen canvas is visible beneath the delicate brushstrokes.  The work is signed and dated

text: One of four surviving Bruegel paintings in

text: distemper

text: , the work is a

text: tüchlein

text: , a type of light painting that uses tempera made from pigment mixed with water-soluble glue. This medium was widely used in painting and

text: manuscript illumination

text: before the advent of oil paint.  It is not known from whom Bruegel learnt its use, but amongst those speculated are his mother-in-law, illuminator

text: Mayken Verhulst

text: ; his teacher

text: Pieter Coecke van Aelst

text: ; and painter and illuminator

text: Giulio Clovio

text: , with whom he resided in Italy and whom he helped paint miniatures in distemper. Due to the high perishability of linen cloth and the solubility of hide glue, tüchleins do not preserve well and are difficult to restore.  The Blind Leading the Blind is in good condition and has suffered no more than some erosion, such as of a herdsman and some fowl in the middle ground.  The grain of the linen canvas is visible beneath the delicate brushstrokes.  The work is signed and dated

text: In 1903, Prosper-René Blondlot was working on X-rays (as were many physicists of the era) and noticed a new visible radiation that could penetrate aluminium. He devised experiments in which a barely visible object was illuminated by these N-rays, and thus became "more visible". Blondlot claimed that N-rays were causing a small visual reaction, too small to be seen under normal illumination, but just visible when most normal light sources were removed and the target was just barely visible to begin with.

text: In 1903,

text: Prosper-René Blondlot

text: was working on

text: X-ray

text: s (as were many physicists of the era) and noticed a new visible radiation that could penetrate

text: aluminium

text: . He devised experiments in which a barely visible object was illuminated by these N-rays, and thus became "more visible". Blondlot claimed that N-rays were causing a small visual reaction, too small to be seen under normal illumination, but just visible when most normal light sources were removed and the target was just barely visible to begin with.

text: Tracking movement can help determine how well drugs are being distributed or how substances are metabolized. It is difficult to track a small group of cells throughout the body, so scientists used to dye the cells. These dyes needed to be excited by light of a certain wavelength in order for them to light up. While different color dyes absorb different frequencies of light, there was a need for as many light sources as cells. A way around this problem is with luminescent tags. These tags are quantum dots attached to proteins that penetrate cell membranes. The dots can be random in size, can be made of bio-inert material, and they demonstrate the nanoscale property that color is size-dependent. As a result, sizes are selected so that the frequency of light used to make a group of quantum dots fluoresce is an even multiple of the frequency required to make another group incandesce. Then both groups can be lit with a single light source. They have also found a way to insert nanoparticles into the affected parts of the body so that those parts of the body will glow showing the tumor growth or shrinkage or also organ trouble.

text: Tracking movement can help determine how well drugs are being distributed or how substances are metabolized. It is difficult to track a small group of cells throughout the body, so scientists used to dye the cells. These dyes needed to be excited by light of a certain wavelength in order for them to light up. While different color dyes absorb different frequencies of light, there was a need for as many light sources as cells. A way around this problem is with luminescent tags. These tags are

text: quantum dots

text: attached to proteins that penetrate cell membranes. The dots can be random in size, can be made of bio-inert material, and they demonstrate the nanoscale property that color is size-dependent. As a result, sizes are selected so that the frequency of light used to make a group of quantum dots fluoresce is an even multiple of the frequency required to make another group incandesce. Then both groups can be lit with a single light source. They have also found a way to insert

text: nanoparticles

text: into the affected parts of the body so that those parts of the body will glow showing the tumor growth or shrinkage or also organ trouble.

text: While the beam is visible at its listed range, it is a more focused beam than that produced by a glass Fresnel lens.  Some navigators don't like this, finding it harder to see under some conditions. It is easy to see the difference from many points around Boston Harbor, where the VRB-25 at The Graves Light and the 2nd order glass Fresnel lens at Boston Light are both visible. Of course, the original first order Fresnel lens at The Graves stood twelve feet high and weighed several tons.  Its many pieces of glass required periodic careful cleaning and alignment.

text: While the beam is visible at its listed range, it is a more focused beam than that produced by a glass Fresnel lens.  Some navigators don't like this, finding it harder to see under some conditions. It is easy to see the difference from many points around Boston Harbor, where the VRB-25 at

text: The Graves Light

text: and the 2nd order glass Fresnel lens at

text: Boston Light

text: are both visible. Of course, the original first order Fresnel lens at The Graves stood twelve feet high and weighed several tons.  Its many pieces of glass required periodic careful cleaning and alignment.

text: Trumbull and Dykstra found the Magicam models problematic. The Klingon cruiser's lighting was so dim that there was no way to make them bright enough on film. As Trumbull also felt the Enterprises lights were ill-suited for his needs, he rewired both models. He questioned that the Enterprise could be traveling years from any source of light and yet still be fully illuminated. Instead of having the ship completely dark save for viewports, Trumbull came up with a system of self-illumination; he pictured the ship as something like an oceanliner, "a grand lady of the seas at night". A similar method was used on the Klingon cruiser model, but he made it less well-lit to convey a different look than the clean visuals of the Federation—the cruiser was meant to evoke "an enemy submarine in World War II that's been out at sea for too long". The models were filmed in multiple passes and composited together in post-production; multiple passes with only the model's lighting running were added to the original pass for the final look. The Klingon cruiser sequence was developed to avoid an opening similar to Star Wars, with one model used for all three seen in the film.

text: The overwhelming majority of Orthodox halakhic authorities maintain that turning on an incandescent light on Shabbat violates a Biblical prohibition.  An incandescent light bulb generates light by causing electric current to flow through a metal filament.  The resistance to current flow generates light and heat.  Sources in the Torah and Talmud forbid similar cases.

text: The overwhelming majority of Orthodox halakhic authorities maintain that turning on an incandescent light on Shabbat violates a Biblical prohibition.  An incandescent light bulb generates light by causing

text: electric current

text: to flow through a metal filament.  The

text: resistance

text: to current flow generates light and heat.  Sources in the

text: Torah

text: and

text: Talmud

text: forbid similar cases.

text: From the side, a beam of light is only visible if part of the light is scattered by objects: tiny particles like dust, water droplets (mist, fog, rain), hail, snow, or smoke, or larger objects such as birds. If there are many objects in the light path, then it appears as a continuous beam, but if there are only a few objects, then the light is visible as a few individual bright points. In any case, this scattering of light from a beam, and the resultant visibility of a light beam from the side, is known as the Tyndall effect.

text: From the side, a beam of light is only visible if part of the light is scattered by objects: tiny particles like

text: dust

text: , water droplets (

text: mist

text: fog

text: rain

text: hail

text: snow

text: , or

text: smoke

text: , or larger objects such as

text: bird

text: s. If there are many objects in the light path, then it appears as a continuous beam, but if there are only a few objects, then the light is visible as a few individual bright points. In any case, this scattering of light from a beam, and the resultant visibility of a light beam from the side, is known as the

text: Tyndall effect

text: Commonly referred as phosphorescence, persistent luminescence is the phenomenon encountered in materials which make them glow in the dark after the end of an excitation with UV or visible light.

text: Commonly referred as phosphorescence, persistent luminescence is the phenomenon encountered in materials which make them glow in the dark after the end of an

text: excitation

text: with UV or visible light.

text: In the marine environment, use of luminescence for mate attraction is chiefly known among ostracods, small shrimplike crustaceans, especially in the Cyprididae family. Pheromones may be used for long-distance communication, with bioluminescence used at close range to enable mates to "home in". A polychaete worm, the Bermuda fireworm creates a brief display, a few nights after the full moon, when the female lights up to attract males.

text: In the marine environment, use of luminescence for mate attraction is chiefly known among

text: ostracod

text: s, small shrimplike

text: crustacean

text: s, especially in the

text: Cyprididae

text: family.

text: Pheromone

text: s may be used for long-distance communication, with bioluminescence used at close range to enable mates to "home in". A

text: polychaete

text: worm, the

text: Bermuda fireworm

text: creates a brief display, a few nights after the full moon, when the female lights up to attract males.

text: Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10 to 7.00 × 10 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). This wavelength means a frequency range of roughly 430–750 terahertz (THz).

text: Visible light is usually defined as having

text: wavelength

text: s in the range of 400–700

text: nanometre

text: s (nm), or 4.00 × 10 to 7.00 × 10 m, between the

text: infrared

text: (with longer wavelengths) and the

text: ultraviolet

text: (with shorter wavelengths). This wavelength means a

text: frequency

text: range of roughly 430–750

text: terahertz

text: (THz).

text: Infrared is used in night vision equipment when there is insufficient visible light to see. Night vision devices operate through a process involving the conversion of ambient light photons into electrons that are then amplified by a chemical and electrical process and then converted back into visible light. Infrared light sources can be used to augment the available ambient light for conversion by night vision devices, increasing in-the-dark visibility without actually using a visible light source.

text: Infrared is used in night vision equipment when there is insufficient

text: visible light

text: to see.

text: Night vision devices

text: operate through a process involving the conversion of ambient light photons into electrons that are then amplified by a chemical and electrical process and then converted back into visible light. Infrared light sources can be used to augment the available ambient light for conversion by night vision devices, increasing in-the-dark visibility without actually using a visible light source.

text: Different activities or scenarios call for different color temperature-illuminance pairs: preferred light sources change depending on the scenario the source is illuminating. Individuals did prefer color temperature-illuminance pairs within the comfortable region for dining, socializing and studying, but also preferred color temperature-illuminance pairs that were in the lower uncomfortable region for night time activities and preparing for bed. This is linked to the Purkinje effect; individuals who desire some light at night time desire lower (redder) color temperatures even if luminance levels are very low.

text: Different activities or scenarios call for different color temperature-illuminance pairs: preferred light sources change depending on the scenario the source is illuminating. Individuals did prefer color temperature-illuminance pairs within the comfortable region for

text: dining

text: socializing

text: and

text: studying

text: , but also preferred color temperature-illuminance pairs that were in the lower uncomfortable region for night time activities and preparing for bed. This is linked to the Purkinje effect; individuals who desire some light at night time desire lower (redder) color temperatures even if luminance levels are very low.

text: Lycopene is a symmetrical tetraterpene assembled from eight isoprene units. It is a member of the carotenoid family of compounds, and because it consists entirely of carbon and hydrogen, is also a carotene. Isolation procedures for lycopene were first reported in 1910, and the structure of the molecule was determined by 1931. In its natural, all-trans form, the molecule is long and straight, constrained by its system of eleven conjugated double bonds. Each extension in this conjugated system reduces the energy required for electrons to transition to higher energy states, allowing the molecule to absorb visible light of progressively longer wavelengths. Lycopene absorbs all but the longest wavelengths of visible light, so it appears red.

text: Lycopene is a symmetrical

text: tetraterpene

text: assembled from eight

text: isoprene

text: units. It is a member of the carotenoid family of compounds, and because it consists entirely of carbon and hydrogen, is also a

text: carotene

text: . Isolation procedures for lycopene were first reported in 1910, and the structure of the molecule was determined by 1931. In its natural, all-trans form, the molecule is long and straight, constrained by its system of eleven conjugated double bonds. Each extension in this

text: conjugated system

text: reduces the energy required for electrons to transition to higher

text: energy state

text: s, allowing the molecule to absorb visible light of progressively longer wavelengths. Lycopene absorbs all but the longest wavelengths of visible light, so it appears red.

text: Two general types of infrared / near-infrared (also known as active light) eye tracking techniques are used: bright-pupil and dark-pupil.  Their difference is based on the location of the illumination source with respect to the optics.  If the illumination is coaxial with the optical path, then the eye acts as a retroreflector as the light reflects off the retina creating a bright pupil effect similar to red eye.  If the illumination source is offset from the optical path, then the pupil appears dark because the retroreflection from the retina is directed away from the camera.

text: Two general types of infrared / near-infrared (also known as active light) eye tracking techniques are used: bright-pupil and dark-pupil.  Their difference is based on the location of the illumination source with respect to the optics.  If the illumination is

text: coaxial

text: with the optical path, then the eye acts as a

text: retroreflector

text: as the light reflects off the

text: retina

text: creating a bright pupil effect similar to

text: red eye

text: .  If the illumination source is offset from the optical path, then the pupil appears dark because the retroreflection from the retina is directed away from the camera.

text: The illumination of light as a practical use to visibly reveal what may be shaded or in the dark is common. Light as an art form is a function of art works and entertainment, it is a projection source and a backlighting source, for colours, focal or focus points and can be an element to enhance or change atmosphere or mood in areas or on objects.

text: The illumination of

text: light

text: as a practical use to visibly reveal what may be shaded or in the dark is common. Light as an art form is a function of art works and entertainment, it is a

text: projection

text: source and a

text: backlight

text: ing source, for colours, focal or focus points and can be an element to enhance or change atmosphere or mood in areas or on objects.

text: The illumination provided on a surface by a point source equals the number of lux just described times the cosine of the angle between a ray coming from the source and a normal to the surface. The illumination provided by a light source that covers a large solid angle is proportional to the cosine of the angle between the surface normal and a sort of barycentre of the light source, so long as all of the source is above the plane of the surface. The number of lux falling on the surface equals this cosine times a number (in lux) that characterizes the source from the point of view in question.

text: The illumination provided on a surface by a point source equals the number of lux just described times the cosine of the angle between a ray coming from the source and a

text: normal

text: to the surface. The illumination provided by a light source that covers a large solid angle is proportional to the cosine of the angle between the surface normal and a sort of

text: barycentre

text: of the light source, so long as all of the source is above the plane of the surface. The number of lux falling on the surface equals this cosine times a number (in lux) that characterizes the source from the point of view in question.

text: Fluorescent lamps convert more of the input power to visible light than incandescent lamps, though as of 2013 LEDs are sometimes even more efficient and are more rapidly increasing in efficiency. A typical 100 watt tungsten filament incandescent lamp may convert only 5% of its power input to visible white light (400–700 nm wavelength), whereas typical fluorescent lamps convert about 22% of the power input to visible white light.

text: Fluorescent lamps convert more of the input power to visible light than incandescent lamps, though as of 2013

text: LEDs

text: are sometimes even more efficient and are more rapidly increasing in efficiency. A typical 100 watt tungsten filament incandescent lamp may convert only 5% of its power input to visible white light (400–700 nm wavelength), whereas typical fluorescent lamps convert about 22% of the power input to visible white light.

text: The culture of Surin is also strongly influenced by the Kuy people, most visibly in the activity surrounding elephants that is so prominent in the province. Surin is the source of approximately a quarter of all the domesticated elephants in Thailand and the capture, training and raising of these elephants is conducted by people belonging to the Kuy ethnicity. This is such an important activity to Surin and a source of pride to the Kuy people, that celebrations such as Thai Elephant Day () and the Surin Elephant Round-up are held annually on the second and third weeks, respectively, of November. The festivals include light and sound shows describing the legends of the Thai elephants and a fair at Si Narong Stadium featuring parades, floats, contests such as tug of war between elephants and men and demonstrations of war elephants.

text: The culture of Surin is also strongly influenced by the Kuy people, most visibly in the activity surrounding

text: elephants

text: that is so prominent in the province. Surin is the source of approximately a quarter of all the domesticated elephants in Thailand and the capture, training and raising of these elephants is conducted by people belonging to the Kuy ethnicity. This is such an important activity to Surin and a source of pride to the Kuy people, that celebrations such as Thai Elephant Day () and the

text: Surin Elephant Round-up

text: are held annually on the second and third weeks, respectively, of November. The festivals include light and sound shows describing the legends of the Thai elephants and a fair at Si Narong Stadium featuring parades, floats, contests such as tug of war between elephants and men and demonstrations of war elephants.

text: Working in the basement of his home on Orchard Street in Elizabeth, New Jersey, Diehl invented a lamp that was different from Thomas Edison's incandescent electric lamp, which was patented in 1879. Diehl's lamp had no lead-in wires. In 1882 Diehl obtained the first patent on this induction incandescent lamp. The base of the lamp contained a wire coil that coupled with a primary coil in the lamp socket, causing current to flow through the lamp without the need for lead-in wires. Two additional patents were granted in 1883, followed by patents for electrical lighting systems in 1885 and 1886.

text: Working in the basement of his home on Orchard Street in Elizabeth, New Jersey, Diehl invented a lamp that was different from

text: Thomas Edison

text: 's incandescent electric lamp, which was patented in 1879. Diehl's lamp had no lead-in wires. In 1882 Diehl obtained the first patent on this induction incandescent lamp. The base of the lamp contained a wire coil that coupled with a primary coil in the lamp socket, causing current to flow through the lamp without the need for lead-in wires. Two additional patents were granted in 1883, followed by patents for electrical lighting systems in 1885 and 1886.

text: The improvement in the light referred to had begun in 1845 when the reflectors were changed from 14 to . In 1848 the 18 lamps were changed to 15 lamps with  reflectors and the light had become visible in clear weather at a distance of . In 1854 a first-order Fresnel lens with flashing white light was substituted for the old reflecting apparatus, and the tower was raised to .

text: Incandescent bulbs have been replaced in many applications by other types of electric light, such as fluorescent lamps, compact fluorescent lamps (CFL), cold cathode fluorescent lamps (CCFL), high-intensity discharge lamps, and light-emitting diode lamps (LED). Some jurisdictions, such as the European Union, China, Canada and United States, are in the process of phasing out the use of incandescent light bulbs while others, including Colombia, Mexico, Cuba, Argentina, Brazil and Australia, have prohibited them already.

text: Incandescent bulbs have been replaced in many applications by other types of electric light, such as

text: fluorescent lamp

text: s,

text: compact fluorescent lamp

text: s (CFL),

text: cold cathode fluorescent lamp

text: s (CCFL),

text: high-intensity discharge lamp

text: s, and

text: light-emitting diode lamp

text: s (LED). Some jurisdictions, such as the

text: European Union

text: China

text: Canada

text: and

text: United States

text: , are in the process of

text: phasing out the use of incandescent light bulbs

text: while others, including

text: Colombia

text: Mexico

text: Cuba

text: Argentina

text: Brazil

text: and

text: Australia

text: , have prohibited them already.

text: Larval and larviform female glowworms are predators, feeding on millipedes and other arthropods occurring in soil and litter. The winged males, which are often attracted to lights at night, are short-lived and probably do not feed. Females are much larger than the males and are completely larviform. Males may be luminescent, but females and larvae have a series of luminescent organs on trunk segments which emit yellow or green light, and sometimes an additional head organ which emits red light, as in railroad worms.

text: Larval and

text: larviform female

text: glowworms are

text: predator

text: s, feeding on

text: millipede

text: s and other

text: arthropod

text: s occurring in

text: soil

text: and

text: litter

text: . The winged males, which are often attracted to lights at night, are short-lived and probably do not feed. Females are much larger than the males and are completely larviform. Males may be luminescent, but females and larvae have a series of luminescent organs on trunk segments which emit yellow or green light, and sometimes an additional head organ which emits red light, as in

text: railroad worm

text: s.

text: Many other light sources, such as fluorescent lamps, or LEDs (light emitting diodes) emit light primarily by processes other than thermal radiation. This means that the emitted radiation does not follow the form of a black-body spectrum. These sources are assigned what is known as a correlated color temperature (CCT). CCT is the color temperature of a black-body radiator which to human color perception most closely matches the light from the lamp. Because such an approximation is not required for incandescent light, the CCT for an incandescent light is simply its unadjusted temperature, derived from the comparison to a black-body radiator.

text: Many other light sources, such as

text: fluorescent lamp

text: s, or

text: LED

text: s (light emitting diodes) emit light primarily by processes other than thermal radiation. This means that the emitted radiation does not follow the form of a

text: black-body spectrum

text: . These sources are assigned what is known as a

text: correlated color temperature

text: (CCT). CCT is the color temperature of a black-body radiator which to

text: human color perception

text: most closely matches the light from the lamp. Because such an approximation is not required for incandescent light, the CCT for an incandescent light is simply its unadjusted temperature, derived from the comparison to a black-body radiator.

text: Incandescent bulbs are much less efficient than most other types of electric lighting; incandescent bulbs convert less than 5% of the energy they use into visible light, with standard light bulbs averaging about 2.2%. The remaining energy is converted into heat. The luminous efficacy of a typical incandescent bulb is 16 lumens per watt, compared with 60 lm/W for a compact fluorescent bulb or 150 lm/W for some white LED lamps. Some applications of the incandescent bulb deliberately use the heat generated by the filament. Such applications include incubators, brooding boxes for poultry, heat lights for reptile tanks, infrared heating for industrial heating and drying processes, lava lamps, and the Easy-Bake Oven toy. Incandescent bulbs typically have short lifetimes compared with other types of lighting; around 1,000 hours for home light bulbs versus typically 10,000 hours for compact fluorescents and 30,000 hours for lighting LEDs.

text: Incandescent bulbs are much less efficient than most other types of electric lighting; incandescent bulbs convert less than 5% of the energy they use into visible light, with standard light bulbs averaging about 2.2%. The remaining energy is converted into heat. The

text: luminous efficacy

text: of a typical incandescent bulb is 16

text: lumen

text: s per watt, compared with 60 lm/W for a

text: compact fluorescent

text: bulb or 150 lm/W for some white

text: LED lamp

text: s. Some applications of the incandescent bulb deliberately use the heat generated by the filament. Such applications include incubators, brooding boxes for poultry, heat lights for

text: reptile

text: tanks

text: infrared heating

text: for industrial heating and drying processes,

text: lava lamp

text: s, and the

text: Easy-Bake Oven

text: toy. Incandescent bulbs typically have short lifetimes compared with other types of lighting; around 1,000 hours for home light bulbs versus typically 10,000 hours for compact fluorescents and 30,000 hours for lighting LEDs.

text: The Hornblende Schist continues south of the South Pier for  where there is a fault boundary with the serpentine. The serpentine continues towards the south west, with a further boundary at the Vro Rock  away. The serpentinite is clearly visible in the high Mullion Cliffs adjacent to what is now a massive scree slope. In 1752 these cliffs were part of a quarry site from which the mineral soapstone, a talc, known then as soaprock, or steatite was extracted. Remains of the mineral are still visible in the form of veins of a white or light-coloured mineral occasionally up to  thick, running at an angle of 45° along the serpentine cliff face.

text: The Hornblende Schist continues south of the South Pier for  where there is a fault boundary with the

text: serpentine

text: . The serpentine continues towards the south west, with a further boundary at the Vro Rock  away. The serpentinite is clearly visible in the high Mullion Cliffs adjacent to what is now a massive scree slope. In 1752 these cliffs were part of a quarry site from which the mineral

text: soapstone

text: , a

text: talc

text: , known then as soaprock, or

text: steatite

text: was extracted. Remains of the mineral are still visible in the form of veins of a white or light-coloured mineral occasionally up to  thick, running at an angle of 45° along the serpentine cliff face.

text: The primary properties of visible light are intensity, propagation direction, frequency or wavelength spectrum, and polarization, while its speed in a vacuum, 299,792,458 metres per second, is one of the fundamental constants of nature. Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in a vacuum.

text: The primary properties of visible light are

text: intensity

text: , propagation direction, frequency or wavelength

text: spectrum

text: , and

text: polarization

text: , while its

text: speed

text: in a vacuum, 299,792,458 metres per second, is one of the fundamental

text: constants

text: of nature. Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in a vacuum.

text: Illumination was created by Bryan Lunduke, and first released in May 2010. The earliest known public mention of Illumination was on the April 11, 2010 episode of The Linux Action Show!.

text: Illumination was created by

text: Bryan Lunduke

text: , and first released in May 2010. The earliest known public mention of Illumination was on the April 11, 2010 episode of

text: The Linux Action Show!

text: A fluorescent lamp or a fluorescent tube is a low pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An  electric current in the gas excites mercury vapor which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than incandescent lamps. The typical luminous efficacy of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output, but less than that of a typical LED bulb.

text: A fluorescent lamp or a fluorescent tube is a low pressure

text: mercury-vapor

text: gas-discharge lamp

text: that uses

text: fluorescence

text: to produce visible light. An

text: electric current

text: in the gas

text: excites

text: mercury

text: vapor which produces short-wave

text: ultraviolet

text: light that then causes a

text: phosphor

text: coating on the inside of the lamp to

text: glow

text: . A fluorescent lamp converts electrical energy into useful light much more efficiently than

text: incandescent lamp

text: s. The typical

text: luminous efficacy

text: of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output, but less than that of a typical LED bulb.

text: Freshwater aquarium lighting is commonly provided by screw-in incandescent bulbs, fluorescent tubes and LED lamps. Incandescent lighting is becoming less popular because it uses much more energy and produces more heat than the other lighting types. Compact fluorescent lighting with a compatible screw-in base is frequently used as a direct replacement for incandescent bulbs.

text: Freshwater aquarium lighting is commonly provided by

text: screw-in

text: incandescent bulbs

text: fluorescent tubes

text: and

text: LED lamps

text: . Incandescent lighting is becoming less popular because it uses much more energy and produces more heat than the other lighting types.

text: Compact fluorescent lighting

text: with a compatible screw-in base is frequently used as a direct replacement for incandescent bulbs.

text: More recently, Michell has become known for his letter to Cavendish, published in 1784,  on the effect of gravity on light. This paper was rediscovered in the 1970s and is now recognised as anticipating several astronomical ideas that had been considered to be 20th century innovations. Michell is now credited with being the first to study the case of a heavenly object massive enough to prevent light from escaping (the concept of escape velocity was well known at the time). Such an object, which he called a dark star, would not be directly visible, but could be identified by the motions of a companion star if it was part of a binary system. The classical minimum radius for escape assuming light behaved like particles of matter is numerically equal to the Schwarzschild Radius in general relativity.  Michell also suggested using a prism to measure what is now known as gravitational redshift, the gravitational weakening of starlight due to the surface gravity of the source. Michell acknowledged that some of these ideas were not technically practical at the time, but wrote that he hoped they would be useful to future generations. By the time that Michell's paper was rediscovered nearly two centuries later, these ideas had been reinvented by others.

text: More recently, Michell has become known for his letter to Cavendish, published in 1784,  on the effect of gravity on light. This paper was rediscovered in the 1970s and is now recognised as anticipating several astronomical ideas that had been considered to be 20th century innovations. Michell is now credited with being the first to study the case of a heavenly object massive enough to prevent light from escaping (the concept of

text: escape velocity

text: was well known at the time). Such an object, which he called a

text: dark star

text: , would not be directly visible, but could be identified by the motions of a companion star if it was part of a binary system. The classical minimum radius for escape assuming light behaved like particles of matter is numerically equal to the

text: Schwarzschild Radius

text: in

text: general relativity

text: .  Michell also suggested using a

text: prism

text: to measure what is now known as

text: gravitational redshift

text: , the gravitational weakening of starlight due to the surface gravity of the source. Michell acknowledged that some of these ideas were not technically practical at the time, but wrote that he hoped they would be useful to future generations. By the time that Michell's paper was rediscovered nearly two centuries later, these ideas had been reinvented by others.

text: Light from many different sources contains various colors, each with its own brightness or intensity.  A rainbow, or prism, sends these component colors in different directions, making them individually visible at different angles.  A graph of the intensity plotted against the frequency (showing the brightness of each color) is the frequency spectrum of the light.  When all the visible frequencies are present equally, the perceived color of the light is white, and the spectrum is a flat line.  Therefore, flat-line spectrums in general are often referred to as white, whether they represent light or another type of wave phenomenon (sound, for example, or vibration in a structure).

text: Light from many different sources contains various colors, each with its own brightness or intensity.  A rainbow, or

text: prism

text: , sends these component colors in different directions, making them individually visible at different angles.  A graph of the intensity plotted against the frequency (showing the brightness of each color) is the frequency spectrum of the light.  When all the visible frequencies are present equally, the perceived color of the light is white, and the spectrum is a flat line.  Therefore, flat-line spectrums in general are often referred to as white, whether they represent light or another type of wave phenomenon (sound, for example, or vibration in a structure).

text: Measurement of light or photometry is generally concerned with the amount of useful light falling on a surface and the amount of light emerging from a lamp or other source, along with the colors that can be rendered by this light. The human eye responds differently to light from different parts of the visible spectrum, therefore photometric measurements must take the luminosity function into account when measuring the amount of useful light. The basic SI unit of measurement is the candela (cd), which describes the luminous intensity, all other photometric units are derived from the candela. Luminance for instance is a measure of the density of luminous intensity in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square metre (cd/m). The CGS unit of luminance is the stilb, which is equal to one candela per square centimetre or 10 kcd/m. The amount of useful light emitted from a source or the luminous flux is measured in lumen (lm).

text: Measurement of light or

text: photometry

text: is generally concerned with the amount of useful light falling on a surface and the amount of light emerging from a lamp or other source, along with the colors that can be rendered by this light. The human eye responds differently to light from different parts of the visible spectrum, therefore photometric measurements must take the

text: luminosity function

text: into account when measuring the amount of useful light. The basic

text: SI

text: unit of measurement is the

text: candela

text: (cd), which describes the luminous intensity, all other photometric units are derived from the candela.

text: Luminance

text: for instance is a measure of the density of luminous intensity in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given

text: solid angle

text: . The SI unit for luminance is

text: candela

text: per

text: square metre

text: (cd/m). The

text: CGS

text: unit of luminance is the

text: stilb

text: , which is equal to one candela per square centimetre or 10 kcd/m. The amount of useful light emitted from a source or the

text: luminous flux

text: is measured in

text: lumen

text: (lm).

text: Materials which do not allow the transmission of any light wave frequencies are called opaque. Such substances may have a chemical composition which includes what are referred to as absorption centers. Most materials are composed of materials which are selective in their absorption of light frequencies. Thus they absorb only certain portions of the visible spectrum. The frequencies of the spectrum which are not absorbed are either reflected back or transmitted for our physical observation. In the visible portion of the spectrum, this is what gives rise to color.

text: Materials which do not allow the transmission of any light wave frequencies are called

text: opaque

text: . Such substances may have a chemical composition which includes what are referred to as absorption centers. Most materials are composed of materials which are selective in their absorption of light frequencies. Thus they absorb only certain portions of the visible spectrum. The frequencies of the spectrum which are not absorbed are either reflected back or transmitted for our physical observation. In the visible portion of the spectrum, this is what gives rise to color.

text: For a polygonal model, the volume is usually formed by classifying each face in the model as either facing toward the light source or facing away from the light source. The set of all edges that connect a toward-face to an away-face form the silhouette with respect to the light source. The edges forming the silhouette are extruded away from the light to construct the faces of the shadow volume. This volume must extend over the range of the entire visible scene; often the dimensions of the shadow volume are extended to infinity to accomplish this (see optimization below.) To form a closed volume, the front and back end of this extrusion must be covered. These coverings are called "caps". Depending on the method used for the shadow volume, the front end may be covered by the object itself, and the rear end may sometimes be omitted (see depth pass below).

text: For a polygonal model, the volume is usually formed by classifying each face in the model as either facing toward the light source or facing away from the light source. The set of all edges that connect a toward-face to an away-face form the silhouette with respect to the light source. The edges forming the silhouette are extruded away from the light to construct the faces of the shadow volume. This volume must extend over the range of the entire visible scene; often the dimensions of the shadow volume are extended to infinity to accomplish this (see

text: optimization

text: below.) To form a closed volume, the front and back end of this extrusion must be covered. These coverings are called "caps". Depending on the method used for the shadow volume, the front end may be covered by the object itself, and the rear end may sometimes be omitted (see

text: depth pass

text: below).

text: The simple logic of tasrif based understanding is that 'light', to be seen, does not need an external source of light'.

text: Most of the plastic bottles used are recycled 1.5 liter bottles.  After being filled with water and a little bleach, the bottle is pushed through a steel sheet that serves as a metal lock to prevent it from slipping.  It is then embedded into a corrugated iron roof. A small part of the bottle is left outside while the rest of it protrudes into the house.  Sealant is put around the hole made in the roof to keep it weather proof. The refractive properties of water ensures that the light from the sun that reaches the inside of the bottle becomes omni-directional mimicking an electric light bulb and emitting the same amount of light as a 40–60 W incandescent bulb depending on the amount of solar insolation available.  Adding bleach to the water prevents it from turning green with algae and ensures a high quality light keeping the water clear for a longer time. In order to facilitate use of the invention through open source mechanisms, step-by-step guides on materials and installation are available online.

text: A material can emit light either through incandescence, where all atoms radiate, or by luminescence, where only a small fraction of atoms, called emission centers or luminescence centers, emit light. In inorganic phosphors, these inhomogeneities in the crystal structure are created usually by addition of a trace amount of dopants, impurities called activators. (In rare cases dislocations or other crystal defects can play the role of the impurity.) The wavelength emitted by the emission center is dependent on the atom itself, and on the surrounding crystal structure.

text: A material can emit light either through

text: incandescence

text: , where all atoms radiate, or by

text: luminescence

text: , where only a small fraction of atoms, called emission centers or luminescence centers, emit light. In inorganic phosphors, these inhomogeneities in the crystal structure are created usually by addition of a trace amount of

text: dopant

text: s, impurities called

text: activators

text: . (In rare cases

text: dislocation

text: s or other

text: crystal defect

text: s can play the role of the impurity.) The wavelength emitted by the emission center is dependent on the atom itself, and on the surrounding crystal structure.

text: While it might seem astonishing that so many longest-lasting light bulbs have been so infrequently turned off, this is the precise reason for their longevity. Most of the wear and tear that leads to burnouts in incandescent light bulbs is caused by turning them on and off, not by burning them. Each time the bulb is turned on and off, the filament is heated and cooled. This causes the material of the filament to expand and contract, in turn causing micro stress cracks to develop. The more the light is turned on and off, the larger these cracks grow, until eventually the filament breaks at some point, in non-spectacular fashion, thus causing the light to burn out.Another reason for the longevity of bulbs is the size, quality and material of the filament.

text: The apparent magnitude of an astronomical object is generally given as an integrated value—if a galaxy is quoted as having a magnitude of 12.5, it means we see the same total amount of light from the galaxy as we would from a star with magnitude 12.5. However, a star is so small it is effectively a point source in most observations (the largest angular diameter, that of R Doradus, is 0.057 ± 0.005 arcsec), whereas a galaxy may extend over several arcseconds or arcminutes. Therefore, the galaxy will be harder to see than the star against the airglow background light. Apparent magnitude is a good indication of visibility if the object is point-like or small, whereas surface brightness is a better indicator if the object is large. What counts as small or large depends on the specific viewing conditions and follows from Ricco's law. In general, in order to adequately assess an object's visibility one needs to know both parameters.

text: The

text: apparent magnitude

text: of an astronomical object is generally given as an integrated value—if a

text: galaxy

text: is quoted as having a magnitude of 12.5, it means we see the same total amount of light from the galaxy as we would from a star with magnitude 12.5. However, a

text: star

text: is so small it is effectively a

text: point source

text: in most observations (the largest

text: angular diameter

text: , that of

text: R Doradus

text: , is 0.057 ± 0.005

text: arcsec

text: ), whereas a galaxy may extend over several

text: arcsecond

text: s or

text: arcminute

text: s. Therefore, the galaxy will be harder to see than the star against the

text: airglow

text: background light. Apparent magnitude is a good indication of visibility if the object is point-like or small, whereas surface brightness is a better indicator if the object is large. What counts as small or large depends on the specific viewing conditions and follows from

text: Ricco's law

text: . In general, in order to adequately assess an object's visibility one needs to know both parameters.

text: To minimize the total primary energy consumption, the many passive and active daylighting techniques are the first daytime solution to employ. For low light level days, non-daylighted spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and solid-state lighting with Light-emitting diode-LED lamps, organic light-emitting diodes, and PLED - polymer light-emitting diodes; and  'low voltage' electrical filament-Incandescent light bulbs, and compact Metal halide, Xenon and Halogen lamps, can be used.

text: To minimize the total primary energy consumption, the many

text: passive

text: and

text: active

text: daylighting

text: techniques are the first daytime solution to employ. For low light level days, non-daylighted spaces, and nighttime; the use of creative-sustainable

text: lighting design

text: using low-energy sources such as 'standard voltage'

text: compact fluorescent lamp

text: s and

text: solid-state lighting

text: with

text: Light-emitting diode

text: LED lamp

text: s,

text: organic light-emitting diode

text: s, and

text: PLED - polymer light-emitting diodes

text: ; and  'low voltage'

text: electrical filament

text: Incandescent light bulb

text: s, and

text: compact Metal halide

text: Xenon

text: and

text: Halogen lamps

text: , can be used.

text: A rare variety of natural sapphire, known as color-change sapphire, exhibits different colors in different light. Color change sapphires are blue in outdoor light and purple under incandescent indoor light, or green to gray-green in daylight and pink to reddish-violet in incandescent light. Color change sapphires come from a variety of locations, including Thailand and Tanzania. The color-change effect is caused by the interaction of the sapphire, which absorbs specific wavelengths of light, and the light-source, whose spectral output varies depending upon the illuminant. Transition-metal impurities in the sapphire, such as chromium and vanadium, are responsible for the color change.

text: A rare variety of natural sapphire, known as color-change sapphire, exhibits different colors in different light. Color change sapphires are blue in outdoor light and purple under

text: incandescent

text: indoor light, or green to gray-green in daylight and pink to reddish-violet in incandescent light. Color change sapphires come from a variety of locations, including

text: Thailand

text: and

text: Tanzania

text: . The color-change effect is caused by the interaction of the sapphire, which absorbs specific wavelengths of light, and the light-source, whose spectral output varies depending upon the illuminant. Transition-metal impurities in the sapphire, such as chromium and vanadium, are responsible for the color change.

text: Fluorescent black light tubes are typically made in the same fashion as normal fluorescent tubes except that a phosphor that emits UVA light instead of visible white light is used.  The type most commonly used for black lights, designated blacklight blue or "BLB" by the industry, has a dark blue filter coating on the tube, which filters out most visible light, so that fluorescence effects can be observed.  These tubes have a dim violet glow when operating.  They should not be confused with "blacklight" or "BL" tubes, which have no filter coating, and have a brighter blue color.  These are made for use in "bug zapper" insect traps, where visible light emission is not a problem.   The phosphor typically used for a near 368 to 371 nanometer emission peak is either europium-doped strontium fluoroborate (:) or europium-doped strontium borate (:) while the phosphor used to produce a peak around 350 to 353 nanometres is lead-doped barium silicate (:). "Blacklight Blue" lamps peak at 365 nm.

text: Fluorescent black light tubes are typically made in the same fashion as normal

text: fluorescent tube

text: s except that a

text: phosphor

text: that emits UVA light instead of visible white light is used.  The type most commonly used for black lights, designated blacklight blue or "BLB" by the industry, has a dark blue filter coating on the tube, which filters out most visible light, so that

text: fluorescence

text: effects can be observed.  These tubes have a dim violet glow when operating.  They should not be confused with "blacklight" or "BL" tubes, which have no filter coating, and have a brighter blue color.  These are made for use in "

text: bug zapper

text: " insect traps, where visible light emission is not a problem.   The phosphor typically used for a near 368 to 371 nanometer emission peak is either

text: europium

text: -doped strontium fluoroborate (:) or europium-doped strontium borate (:) while the phosphor used to produce a peak around 350 to 353 nanometres is lead-doped barium silicate (:). "Blacklight Blue" lamps peak at 365 nm.

text: Nautilus is now recognized as one of Weston's greatest photographs, but all of his images of shells have a greater-than-life quality to them. Weston biographer Ben Maddow has said that what is so remarkable about them "is not in the closeness nor in the monumentality of the forms; or at least, not in these alone. It is instead in the particular light, almost an inward luminescence, that he saw implicit in them before he put them before the lens. Glowing with an interior life . .. one is seeing more than form."

text: UV/visible light from an integrating sphere (and/or other source such as a black body) is focused onto a square test target at the focal plane of a collimator (the mirrors in the diagram), such that a virtual image of the test target will be seen infinitely far away by the camera under test. The camera under test senses a real image of the virtual image of the target, and the sensed image is displayed on a monitor.

text: UV/visible light from an

text: integrating sphere

text: (and/or other source such as a

text: black body

text: ) is focused onto a square test target at the

text: focal plane

text: of a

text: collimator

text: (the mirrors in the diagram), such that a virtual image of the test target will be seen infinitely far away by the camera under test. The camera under test senses a real image of the virtual image of the target, and the sensed image is displayed on a monitor.

text: The term illuminant metameric failure is sometimes used to describe situations where two material samples match when viewed under one light source but not another. Most types of fluorescent lights produce an irregular or peaky spectral emittance curve, so that two materials under fluorescent light might not match, even though they are a metameric match to an incandescent "white" light source with a nearly flat or smooth emittance curve. Material colors that match under one source will often appear different under the other.

text: Ghosting occurs due to poor treatment of the source images, and also due to transitions where demand for an effect goes beyond the limits and technical possibilities of the system. This causes some of the images to remain visible when they should disappear. These effects can depend on the lighting of the lenticular print.

text: One solution to this problem is to use infrared imaging instead of visible light. This is particularly well suited to LWIR cameras that image the heat signature of the target. This is very effective against vehicles like tanks, where the engine produces an excellent high-contrast image to seek on. However, this also greatly adds to the cost of the seeker, especially in the 1970s when this technology was new, and also limits it to uses against vehicles or other hot sources. This means the aircraft has to carry two types of missiles, ones with IR for vehicles, and ones with visible light seekers for attacking other targets like bridges or bunkers.

text: One solution to this problem is to use

text: infrared imaging

text: instead of visible light. This is particularly well suited to LWIR cameras that image the heat signature of the target. This is very effective against vehicles like tanks, where the engine produces an excellent high-contrast image to seek on. However, this also greatly adds to the cost of the seeker, especially in the 1970s when this technology was new, and also limits it to uses against vehicles or other hot sources. This means the aircraft has to carry two types of missiles, ones with IR for vehicles, and ones with visible light seekers for attacking other targets like bridges or bunkers.

text: Examination of a terminator can yield information about the surface of a planetary body; for example, the presence of an atmosphere can create a fuzzier terminator. As the particles within an atmosphere are at a higher elevation, the light source can remain visible even after it has set at ground level. These particles scatter the light, reflecting some of it to the ground. Hence, the sky can remain illuminated even after the sun has set.

text: Examination of a terminator can yield information about the surface of a planetary body; for example, the presence of an

text: atmosphere

text: can create a fuzzier terminator. As the particles within an atmosphere are at a higher elevation, the light source can remain visible even after it has set at ground level. These particles scatter the light, reflecting some of it to the ground. Hence, the sky can remain illuminated even after the sun has set.

text: There are many sources of light. The most common light sources are thermal: a body at a given temperature emits a characteristic spectrum of black-body radiation. A simple thermal source is sunlight, the radiation emitted by the chromosphere of the Sun at around   peaks in the visible region of the electromagnetic spectrum when plotted in wavelength units and roughly 44% of sunlight energy that reaches the ground is visible. Another example is incandescent light bulbs, which emit only around 10% of their energy as visible light and the remainder as infrared. A common thermal light source in history is the glowing solid particles in flames, but these also emit most of their radiation in the infrared, and only a fraction in the visible spectrum. The peak of the blackbody spectrum is in the deep infrared, at about 10 micrometre wavelength, for relatively cool objects like human beings. As the temperature increases, the peak shifts to shorter wavelengths, producing first a red glow, then a white one, and finally a blue-white colour as the peak moves out of the visible part of the spectrum and into the ultraviolet. These colours can be seen when metal is heated to "red hot" or "white hot". Blue-white thermal emission is not often seen, except in stars (the commonly seen pure-blue colour in a gas flame or a welder's torch is in fact due to molecular emission, notably by CH radicals (emitting a wavelength band around 425 nm, and is not seen in stars or pure thermal radiation).

text: There are many sources of light. The most common light sources are thermal: a body at a given

text: temperature

text: emits a characteristic spectrum of

text: black-body

text: radiation. A simple thermal source is

text: sunlight

text: , the radiation emitted by the

text: chromosphere

text: of the

text: Sun

text: at around   peaks in the visible region of the electromagnetic spectrum when plotted in wavelength units and roughly 44% of sunlight energy that reaches the ground is visible. Another example is

text: incandescent light bulb

text: s, which emit only around 10% of their energy as visible light and the remainder as infrared. A common thermal light source in history is the glowing solid particles in

text: flames

text: , but these also emit most of their radiation in the infrared, and only a fraction in the visible spectrum. The peak of the blackbody spectrum is in the deep infrared, at about 10

text: micrometre

text: wavelength, for relatively cool objects like human beings. As the temperature increases, the peak shifts to shorter wavelengths, producing first a red glow, then a white one, and finally a blue-white colour as the peak moves out of the visible part of the spectrum and into the ultraviolet. These colours can be seen when metal is

text: heat

text: ed to "red hot" or "white hot". Blue-white

text: thermal emission

text: is not often seen, except in stars (the commonly seen pure-blue colour in a

text: gas

text: flame or a

text: welder's

text: torch is in fact due to molecular emission, notably by CH radicals (emitting a wavelength band around 425 nm, and is not seen in stars or pure thermal radiation).

text: A scintillator is a material which exhibits the property of luminescence when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, such as an X-ray photon, absorb its energy and scintillate, i.e. reemit the absorbed energy in the form of a small flash of light, typically in the visible range.

text: A scintillator is a material which exhibits the property of

text: luminescence

text: when excited by

text: ionizing radiation

text: . Luminescent materials, when struck by an incoming particle, such as an X-ray photon, absorb its energy and scintillate, i.e. reemit the absorbed energy in the form of a small flash of light, typically in the visible range.

text: The onset of infrared is defined (according to different standards) at various values typically between 700 nm and 800 nm, but the boundary between visible and infrared light is not precisely defined. The human eye is markedly less sensitive to light above 700 nm wavelength, so longer wavelengths make insignificant contributions to scenes illuminated by common light sources. However, particularly intense near-IR light (e.g., from IR lasers, IR LED sources, or from bright daylight with the visible light removed by colored gels) can be detected up to approximately 780 nm, and will be perceived as red light. Intense light sources providing wavelengths as long as 1050 nm can be seen as a dull red glow, causing some difficulty in near-IR illumination of scenes in the dark (usually this practical problem is solved by indirect illumination). Leaves are particularly bright in the near IR, and if all visible light leaks from around an IR-filter are blocked, and the eye is given a moment to adjust to the extremely dim image coming through a visually opaque IR-passing photographic filter, it is possible to see the Wood effect that consists of IR-glowing foliage.

text: The onset of infrared is defined (according to different standards) at various values typically between 700 nm and 800 nm, but the boundary between visible and infrared light is not precisely defined. The human eye is markedly less sensitive to light above 700 nm wavelength, so longer wavelengths make insignificant contributions to scenes illuminated by common light sources. However, particularly intense near-IR light (e.g., from IR

text: laser

text: s, IR LED sources, or from bright daylight with the visible light removed by colored gels) can be detected up to approximately 780 nm, and will be perceived as red light. Intense light sources providing wavelengths as long as 1050 nm can be seen as a dull red glow, causing some difficulty in near-IR illumination of scenes in the dark (usually this practical problem is solved by indirect illumination). Leaves are particularly bright in the near IR, and if all visible light leaks from around an IR-filter are blocked, and the eye is given a moment to adjust to the extremely dim image coming through a visually opaque IR-passing photographic filter, it is possible to see the

text: Wood effect

text: that consists of IR-glowing foliage.

text: Illuminations is the fourth extended play (EP) by English recording artist Little Boots. It was released in the United States and Canada on 9 June 2009 by Elektra Records. Released as a digital download, the extended play was accompanied by a digital booklet and a music video for the song "New in Town". In Canada, Illuminations was also released on CD.

text: Illuminations is the fourth

text: extended play

text: (EP) by English recording artist

text: Little Boots

text: . It was released in the United States and Canada on 9 June 2009 by

text: Elektra Records

text: . Released as a

text: digital download

text: , the extended play was accompanied by a

text: digital booklet

text: and a music video for the song "

text: New in Town

text: ". In Canada, Illuminations was also released on

text: CD

text: Miller noted there appeared to be two colour forms reported across its range, namely a more cream-coloured form with darker shades of brown and grey in its cap that darkens with age, and a more wholly brownish form with paler edges and darker centre to its cap. He found the cream-coloured form to be strongly luminescent—the brightest of any fungus in the genus—with the cap, stipe and gills all glowing. The brown form was generally fainter, with its luminescence restricted to the gills. However, some strongly luminescent wholly brown-coloured mushrooms were recorded, and laboratory experiments showed all interbred freely and produced fertile offspring, leading Miller to conclude that these were phenotypic variants of a single taxon.

text: Miller noted there appeared to be two colour forms reported across its range, namely a more cream-coloured form with darker shades of brown and grey in its cap that darkens with age, and a more wholly brownish form with paler edges and darker centre to its cap. He found the cream-coloured form to be strongly luminescent—the brightest of any fungus in the genus—with the cap, stipe and gills all glowing. The brown form was generally fainter, with its luminescence restricted to the gills. However, some strongly luminescent wholly brown-coloured mushrooms were recorded, and laboratory experiments showed all

text: interbred

text: freely and produced fertile offspring, leading Miller to conclude that these were

text: phenotypic

text: variants of a single

text: taxon

text: Luminescence! is an album by pianist Barry Harris recorded in 1967 and released on the Prestige label.

text: Luminescence! is an album by pianist

text: Barry Harris

text: recorded in 1967 and released on the

text: Prestige

text: label.

text: The spectral power distribution over the visible spectrum from a source can have varying concentrations of relative SPDs.  The interactions between light and matter affect the absorption and reflectance properties of  materials and subsequently produces a color that varies with source illumination.

text: The spectral power distribution over the

text: visible spectrum

text: from a source can have varying concentrations of relative SPDs.  The interactions between light and matter affect the absorption and reflectance properties of  materials and subsequently produces a color that varies with source illumination.

text: The peculiar and picturesque loess hills which characterize the Palouse Prairie are underlain by wind-blown sediments of the Palouse Loess that covers the surface of over  on the Columbia Plateau in southeastern Washington, western Idaho, and northeastern Oregon.  The Palouse Loess forms a fine-grained mantle of variable thickness that lies upon either the Miocene Columbia River Basalt Group, non-glacial Pliocene fluvial sediments of the Ringold Formation, or Pleistocene glacial outburst flood sediments that are known informally as the Hanford formation. At its thickest, the Palouse Loess is up to  thick. It consists of multiple layers of loess separated by multiple well-defined calcrete paleosols and erosional unconformities. The degree of development of individual layers of calcrete together with thermoluminescence and optically stimulated luminescence dating of the loess indicate that each calcrete layer represents a period of thousands to tens of thousands of years of nondeposition, weathering, and soil development that occurred between episodic periods of loess deposition. A consistent sequence of normal-reverse-normal polarity signatures demonstrates that the older layers of loess accumulated between 2 and 1 million years ago. Detailed optically stimulated luminescence dating has shown that the uppermost layer of Palouse Loess accumulated between 15,000 years ago and modern times and the layer of loess underlying it accumulated episodically between about 77,000 and 16,000 years ago. Regional trends in the distribution, thickness, texture, and overall composition of the Palouse Loess indicate that it largely consists of the wind-blown sediments eroded from fine-grained deposits of the Hanford formation that were periodically deposited by repeated Missoula Floods within the Eureka Flats area.

text: The peculiar and picturesque loess hills which characterize the Palouse Prairie are underlain by wind-blown

text: sediment

text: s of the Palouse Loess that covers the surface of over  on the Columbia Plateau in southeastern Washington, western Idaho, and northeastern Oregon.  The Palouse Loess forms a fine-grained mantle of variable thickness that lies upon either the

text: Miocene

text: Columbia River Basalt Group

text: , non-glacial

text: Pliocene

text: fluvial

text: sediments of the Ringold Formation, or

text: Pleistocene

text: glacial

text: outburst flood

text: sediments that are known informally as the Hanford formation. At its thickest, the Palouse Loess is up to  thick. It consists of multiple layers of

text: loess

text: separated by multiple well-defined

text: calcrete

text: paleosol

text: s and erosional

text: unconformities

text: . The degree of development of individual layers of calcrete together with

text: thermoluminescence

text: and

text: optically stimulated luminescence dating

text: of the loess indicate that each calcrete layer represents a period of thousands to tens of thousands of years of nondeposition, weathering, and soil development that occurred between episodic periods of loess deposition. A consistent sequence of

text: normal-reverse-normal polarity signatures

text: demonstrates that the older layers of loess accumulated between 2 and 1 million years ago. Detailed optically stimulated luminescence dating has shown that the uppermost layer of Palouse Loess accumulated between 15,000 years ago and modern times and the layer of loess underlying it accumulated episodically between about 77,000 and 16,000 years ago. Regional trends in the distribution, thickness, texture, and overall composition of the Palouse Loess indicate that it largely consists of the wind-blown sediments eroded from fine-grained deposits of the Hanford formation that were periodically deposited by repeated

text: Missoula Floods

text: within the Eureka Flats area.

text: Due to refraction of light rays in the Earth's atmosphere the Sun, whether  rising or setting, will, in part, show above the horizon even when its disc is completely below the limb of Earth's horizon. Also, viewed from the Earth, the Sun presents as an extended object (a disc) source of light rather than a point source of light, and its upper disk is visible even when the center of the Sun is below Earth's horizon. Thus, sunrise produces daylight  several minutes before  the Sun's geometric center crosses from below the horizon; a converse sequence occurs at dusk, and sunset produces daylight several minutes after the setting of the center of the Sun to below Earth's horizon. These conditions produce differentials of actual durations of light and darkness at various locations on Earth during an equinox; see lengths of equinoctial day and night.

text: Due to

text: refraction

text: of light rays in the Earth's atmosphere the Sun, whether  rising or setting, will, in part, show above the horizon even when its disc is completely below the limb of Earth's horizon. Also, viewed from the Earth, the Sun presents as an extended object (a disc) source of light rather than a point source of light, and its upper disk is visible even when the center of the Sun is below Earth's horizon. Thus, sunrise produces daylight  several minutes before  the Sun's geometric center crosses from below the horizon; a converse sequence occurs at dusk, and sunset produces daylight several minutes after the setting of the center of the Sun to below Earth's horizon. These conditions produce differentials of actual durations of light and darkness at various locations on Earth during an equinox; see

text: lengths of equinoctial day and night

text: In radiometry and colorimetry (or color science more generally), the spectral power distribution (SPD) of a light source is a measure of the power contributed by each frequency or color in a light source. The light spectrum is usually measured at points (often 31) along the visible spectrum, in wavelength space instead of frequency space, which makes it not strictly a spectral density. Some spectrophotometers can measure increments as fine as one to two nanometers. the values are used to calculate other specifications and then plotted to show the spectral attributes of the source. This can be helpful in analyzing the color characteristics of a particular source.

text: In

text: radiometry

text: and

text: colorimetry

text: (or

text: color science

text: more generally), the

text: spectral power distribution

text: (SPD) of a

text: light source

text: is a measure of the power contributed by each frequency or color in a light source. The light spectrum is usually measured at points (often 31) along the

text: visible spectrum

text: , in wavelength space instead of frequency space, which makes it not strictly a spectral density. Some

text: spectrophotometers

text: can measure increments as fine as one to two

text: nanometer

text: s. the values are used to calculate other specifications and then plotted to show the spectral attributes of the source. This can be helpful in analyzing the

text: color

text: characteristics of a particular source.

text: The other important factor for a photocatalyst is the range of light absorbed; though UV-based photocatalysts will perform better per photon than visible light-based photocatalysts due to the higher photon energy, far more visible light reaches the Earth's surface than UV light. Thus, a less efficient photocatalyst that absorbs visible light may ultimately be more useful than a more efficient photocatalyst absorbing solely light with smaller wavelengths.

text: The other important factor for a photocatalyst is the range of light absorbed; though UV-based photocatalysts will perform better per

text: photon

text: than visible light-based photocatalysts due to the higher photon energy, far more visible light reaches the Earth's surface than UV light. Thus, a less efficient photocatalyst that absorbs visible light may ultimately be more useful than a more efficient photocatalyst absorbing solely light with smaller wavelengths.

text: Sources that depend on thermal emission from a solid filament, such as incandescent light bulbs, tend to have low overall efficacy because, as explained by Donald L. Klipstein, “An ideal thermal radiator produces visible light most efficiently at temperatures around 6300 °C (6600 K or 11,500 °F). Even at this high temperature, a lot of the radiation is either infrared or ultraviolet, and the theoretical luminous [efficacy] is 95 lumens per watt. No substance is solid and usable as a light bulb filament at temperatures anywhere close to this. The surface of the sun is not quite that hot.” At temperatures where the tungsten filament of an ordinary light bulb remains solid (below 3683 kelvins), most of its emission is in the infrared.

text: Sources that depend on thermal emission from a solid filament, such as

text: incandescent light bulb

text: s, tend to have low overall efficacy because, as explained by Donald L. Klipstein, “An ideal thermal radiator produces visible light most efficiently at temperatures around 6300 °C (6600 K or 11,500 °F). Even at this high temperature, a lot of the radiation is either infrared or ultraviolet, and the theoretical luminous [efficacy] is 95 lumens per watt. No substance is solid and usable as a light bulb filament at temperatures anywhere close to this. The surface of the sun is not quite that hot.” At temperatures where the

text: tungsten

text: filament of an ordinary light bulb remains solid (below 3683 kelvins), most of its emission is in the

text: infrared

text: The relationship of the Woodward/Evans work on the incandescent bulb that of others, including Edison, on electric light is explained in the following passage of an article in a 1900 issue of Electrical World and Engineer as follows:

text: The Savoy was a state-of-the-art theatre and the first public building in the world to be lit entirely by electricity. In 1881, Sir Joseph Swan, inventor of the incandescent light bulb, supplied about 1,200 Swan incandescent lamps, and the lights were powered by a  generator on open land near the theatre. Carte explained why he had introduced electric light: "The greatest drawbacks to the enjoyment of the theatrical performances are, undoubtedly, the foul air and heat which pervade all theatres. As everyone knows, each gas-burner consumes as much oxygen as many people, and causes great heat beside. The incandescent lamps consume no oxygen, and cause no perceptible heat." The first generator proved too small to power the whole building, and though the entire front-of-house was electrically lit, the stage was lit by gas until 28 December 1881. At that performance, Carte stepped onstage and broke a glowing lightbulb before the audience to demonstrate the safety of the new technology. The Times described the electric lighting as superior, visually, to gaslight. Gaslights were installed as a backup, but they rarely had to be used. The Times concluded that the theatre "is admirably adapted for its purpose, its acoustic qualities are excellent, and all reasonable demands of comfort and taste are complied with." Carte and his manager, George Edwardes (later famous as manager of the Gaiety Theatre), introduced several innovations including numbered seating, free programme booklets, good quality whisky in the bars, the "queue" system for the pit and gallery (an American idea) and a policy of no tipping for cloakroom or other services. Daily expenses at the theatre were about half the possible takings from ticket sales.

text: The Savoy was a state-of-the-art theatre and the first public building in the world to be lit entirely by electricity. In 1881,

text: Sir Joseph Swan

text: , inventor of the

text: incandescent light bulb

text: , supplied about 1,200 Swan incandescent lamps, and the lights were powered by a  generator on open land near the theatre. Carte explained why he had introduced electric light: "The greatest drawbacks to the enjoyment of the theatrical performances are, undoubtedly, the foul air and heat which pervade all theatres. As everyone knows, each

text: gas-burner

text: consumes as much oxygen as many people, and causes great heat beside. The incandescent lamps consume no oxygen, and cause no perceptible heat." The first generator proved too small to power the whole building, and though the entire front-of-house was electrically lit, the stage was lit by gas until 28 December 1881. At that performance, Carte stepped onstage and broke a glowing lightbulb before the audience to demonstrate the safety of the new technology. The Times described the electric lighting as superior, visually, to gaslight. Gaslights were installed as a backup, but they rarely had to be used. The Times concluded that the theatre "is admirably adapted for its purpose, its acoustic qualities are excellent, and all reasonable demands of comfort and taste are complied with." Carte and his manager,

text: George Edwardes

text: (later famous as manager of the

text: Gaiety Theatre

text: ), introduced several innovations including numbered seating, free programme booklets, good quality whisky in the bars, the "queue" system for the pit and gallery (an American idea) and a policy of no tipping for cloakroom or other services. Daily expenses at the theatre were about half the possible takings from ticket sales.

text: Georg Wolf (1873–1938) a Berlin manufacturer of rigid endoscopes, established in 1906, produced the Sussmann flexible gastroscope in 1911(Modlin,Farhadi-Journal of Clinical Gastroenterology, 2000).Karl Storz began producing instruments for ENT specialists in 1945. His intention was to develop instruments which would enable the practitioner to look inside the human body. The technology available at the end of the Second World War was still very modest: The area under examination in the interior of the human body was illuminated with miniature electric lamps; alternatively, attempts were made to reflect light from an external source into the body through the endoscopic tube. Karl Storz pursued a plan: he set out to introduce very bright, but cold light into the body cavities through the instrument, thus providing excellent visibility while at the same time allowing objective documentation by means of image transmission.

text: Georg Wolf (1873–1938) a Berlin manufacturer of rigid endoscopes, established in 1906, produced the Sussmann flexible gastroscope in 1911(Modlin,Farhadi-Journal of Clinical Gastroenterology, 2000).Karl Storz began producing instruments for

text: ENT

text: specialists in 1945. His intention was to develop instruments which would enable the practitioner to look inside the human body. The technology available at the end of the Second World War was still very modest: The area under examination in the interior of the human body was illuminated with miniature electric lamps; alternatively, attempts were made to reflect light from an external source into the body through the endoscopic tube. Karl Storz pursued a plan: he set out to introduce very bright, but cold light into the body cavities through the instrument, thus providing excellent visibility while at the same time allowing objective documentation by means of image transmission.

text: Better signs were soon developed that more resembled today's modern exit sign, with an incandescent bulb inside a rectangular-shaped box that backlit the word "EXIT" on one or both sides.  Being larger than its predecessors, this version of the exit sign solved some of the visibility problem.  The sign was only useful as long as main power remained on.

text: Materials distinguish the interior, with exposed unpainted concrete visibly dominating. The floors and stairways are of polished terrazzo, the walls and ceilings of exposed unpolished concrete. The ground floor accommodates foyer, checkroom, cashier’s desk, and catalogue sales, although most of its almost 500 m2 is used as a multifunctional exhibiting space for KUB Arena projects. Aside from its etched glass outer walls, three differently positioned concrete wall-slabs are visible on the ground floor. These support the Kunsthaus floors and ceilings, structuring the exhibition space on all three upper stories and dividing it from the main stairways, emergency exits, and passenger and freight elevators. Uniformly positioned entrances and exits structure a route through ground floor and upper stories. The latter differ only in ceiling height; each can be used as one large space or scaled down by means of mobile partitions, depending on the project. All three upper stories are top-lit. The ceilings of the exhibition spaces are of loosely joined glass panels. Incident light enters the building on all four sides through light bands and is distributed through the interior volume of each story by the glass ceiling panels. Artificial lighting in the cavity above the glass ceilings complements or replaces daylight as required. These light sources are not visible. The ground and three upper stories and their material and formal aesthetic make up a unity with great potential for art installations. Two subterranean levels complete the spatial program. The first, supplied with daylight by a light pit, accommodates a lecture room, the museum educational center, and sanitary rooms, separated from the non public areas (stock, maintenance, personnel rooms) by translucent glass brick walls. The second subterranean level is closed to the public. It accommodates an originals archive and storage space as well as the electrical, heating, and climate controls.

text: Materials distinguish the interior, with exposed unpainted

text: concrete

text: visibly dominating. The floors and stairways are of polished

text: terrazzo

text: , the walls and ceilings of exposed unpolished concrete. The ground floor accommodates foyer, checkroom, cashier’s desk, and catalogue sales, although most of its almost 500 m2 is used as a multifunctional exhibiting space for KUB Arena projects. Aside from its

text: etched glass

text: outer walls, three differently positioned concrete wall-slabs are visible on the ground floor. These support the Kunsthaus floors and ceilings, structuring the exhibition space on all three upper stories and dividing it from the main stairways,

text: emergency exit

text: s, and passenger and freight

text: elevator

text: s. Uniformly positioned entrances and exits structure a route through ground floor and upper stories. The latter differ only in ceiling height; each can be used as one large space or scaled down by means of mobile partitions, depending on the project. All three upper stories are top-lit. The ceilings of the exhibition spaces are of loosely joined glass panels.

text: Incident light

text: enters the building on all four sides through light bands and is distributed through the interior volume of each story by the glass ceiling panels. Artificial lighting in the cavity above the glass ceilings complements or replaces daylight as required. These light sources are not visible. The ground and three upper stories and their material and formal aesthetic make up a unity with great potential for

text: art installation

text: s. Two subterranean levels complete the spatial program. The first, supplied with daylight by a

text: light pit

text: , accommodates a lecture room, the museum educational center, and sanitary rooms, separated from the non public areas (stock, maintenance, personnel rooms) by translucent glass brick walls. The second subterranean level is closed to the public. It accommodates an originals archive and storage space as well as the electrical, heating, and

text: climate control

text: s.

text: Many of the light sources that emit white light emit light at almost all visible wavelengths (sun light, incandescent lamps of various Color temperatures). This has led to the notion that white light can be defined as a mixture of "all colors" or "all visible wavelengths". This misconception is widespread and might originally stem from the fact that Newton discovered that sunlight is composed of light with wavelengths across the visible spectrum. Concluding that since "all colors" produce white light then white must be made up of "all colors" is a common logical error called affirming the consequent, which might be the cause of the misunderstanding.

text: Many of the light sources that emit white light emit light at almost all visible wavelengths (sun light, incandescent lamps of various

text: Color temperature

text: s). This has led to the notion that white light can be defined as a mixture of "all colors" or "all visible wavelengths". This misconception is widespread and might originally stem from the fact that

text: Newton

text: discovered that sunlight is composed of light with wavelengths across the visible spectrum. Concluding that since "all colors" produce white light then white must be made up of "all colors" is a common logical error called

text: affirming the consequent

text: , which might be the cause of the misunderstanding.

text: It includes techniques such as optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), and thermoluminescence (TL). "Optical dating" typically refers to OSL and IRSL, but not TL.

text: It includes techniques such as

text: optically stimulated luminescence

text: (OSL), infrared stimulated luminescence (IRSL), and

text: thermoluminescence

text: (TL). "Optical dating" typically refers to OSL and IRSL, but not TL.

text: Luminescence in solution obeys the linear Stern–Volmer relationship. Fluorescence of a molecule is quenched by specific analytes, e.g., ruthenium complexes are quenched by oxygen.  When a fluorophore is immobilised within a polymer matrix myriad micro-environments are created. The micro-environments reflect varying diffusion co-efficients for the analyte. This leads to a non-linear relationship between the fluorescence and the quencher (analyte). This relationship is modelled in various ways, the most popular model is the two site model created by James Demas (University of Virginia).

text: Luminescence in solution obeys the linear

text: Stern–Volmer relationship

text: . Fluorescence of a molecule is

text: quenched

text: by specific analytes, e.g.,

text: ruthenium

text: complexes are quenched by oxygen.  When a

text: fluorophore

text: is immobilised within a polymer matrix myriad micro-environments are created. The micro-environments reflect varying diffusion co-efficients for the analyte. This leads to a

text: non-linear

text: relationship between the fluorescence and the quencher (analyte). This relationship is modelled in various ways, the most popular model is the two site model created by James Demas (University of Virginia).

text: Because of the illusion this can give to moving machinery, it is advised that single-phase lighting be avoided in workshops and factories. For example, a factory that is lit from a single-phase supply with basic fluorescent lighting will have a flicker of twice the mains frequency, either at 100 or 120 Hz (depending on country); thus, any machinery rotating at multiples of this frequency may appear to not be turning. Seeing that the most common types of AC motors are locked to the mains frequency, this can pose a considerable hazard to operators of lathes and other rotating equipment. Solutions include deploying the lighting over a full 3-phase supply, or by using high-frequency controllers that drive the lights at safer frequencies. Traditional incandescent light bulbs, which employ filaments that glow continuously, offer another option as well, albeit at the expense of increased power consumption. Smaller incandescent lights can be used as task lighting on equipment to help combat this effect to avoid the cost of operating larger quantities of incandescent lighting in a workshop environment.

text: Visible light includes radiation with wavelengths between 400 nm and 700 nm, meaning that far infrared photons have less energy than visible light photons.

text: Visible light

text: includes radiation with wavelengths between 400 nm and 700 nm, meaning that far infrared photons have less energy than visible light photons.

text: The English version of Luminescence—sharing the same title with the French counterpart—was released in Europe under Sony BMG and in Asia under Universal Music. "Undress Me" was chosen as the first single from the English version. Although it wasn't accompanied with a music video, it debuted at number 13 in Italy, becoming her fifth top 20 single there. It also provided Anggun with her first hit in the Middle East, where the song topped the charts in Lebanon and Turkey. "In Your Mind" was released as the second single and it became a huge hit in Asia. The third single, "Saviour", was used as the soundtrack for the U.S. box office number-one film Transporter 2.

text: The English version of Luminescence—sharing the same title with the French counterpart—was released in Europe under

text: Sony BMG

text: and in Asia under

text: Universal Music

text: . "Undress Me" was chosen as the first single from the English version. Although it wasn't accompanied with a music video, it debuted at number 13 in Italy, becoming her fifth top 20 single there. It also provided Anggun with her first hit in the Middle East, where the song topped the charts in Lebanon and Turkey. "

text: In Your Mind

text: " was released as the second single and it became a huge hit in Asia. The third single, "

text: Saviour

text: ", was used as the soundtrack for the

entity_name: List of 2005 box office number-one films in the United States

text: U.S. box office number-one

text: film

text: Transporter 2

text: The broadcasting booth obscures what appears to be two sources of light, one emanating from the booth, and another from additional equipment barely visible on the far right in the middleground.

text: A safelight is a light source suitable for use in a photographic darkroom. It provides illumination only from parts of the visible spectrum to which the photographic material in use is nearly, or completely, insensitive.

text: A safelight is a

text: light source

text: suitable for use in a photographic

text: darkroom

text: . It provides illumination only from parts of the

text: visible spectrum

text: to which the photographic material in use is nearly, or completely, insensitive.

text: Unlike in UV/visible spectroscopy, ‘standard’, device independent spectra are not easily attained. Several factors influence and distort the spectra, and corrections are necessary to attain ‘true’, i.e. machine-independent, spectra. The different types of distortions will here be classified as being either instrument- or sample-related. Firstly, the distortion arising from the instrument is discussed. As a start, the light source intensity and wavelength characteristics varies over time during each experiment and between each experiment. Furthermore, no lamp has a constant intensity at all wavelengths. To correct this, a beam splitter can be applied after the excitation monochromator or filter to direct a portion of the light to a reference detector.

text: The use of Sidot's blende (zinc sulfide) instead of barium platinocyanide as a luminescence material to make the radioactive rays visible was a commonly accepted improvement. He did several self-experiments with radioactive substances and was able to affirm the damaging effects of radioactive radiation on skin. Because of prolonged contact with radioactive material, fingers of his right hand had to be amputated and he suffered from lung cancer. He died of lung cancer in 1927. His name was included on the Monument to the X-ray and Radium Martyrs of All Nations erected in Hamburg, Germany in 1936.

text: The use of

text: Sidot's blende

text: (zinc sulfide) instead of

text: barium platinocyanide

text: as a luminescence material to make the radioactive rays visible was a commonly accepted improvement. He did several self-experiments with radioactive substances and was able to affirm the damaging effects of radioactive radiation on skin. Because of prolonged contact with radioactive material, fingers of his right hand had to be amputated and he suffered from lung cancer. He died of lung cancer in 1927. His name was included on the

entity_name: Monument to the X-ray and Radium Martyrs of All Nations

text: Monument to the X-ray and Radium Martyrs of All Nations

text: erected in

text: Hamburg

text: , Germany in 1936.

text: An afterglow is a broad high arch of whitish or rosy light appearing in the sky due to very fine particles of dust suspended in the high regions of the atmosphere. An afterglow may appear above the highest clouds in the hour of deepening twilight, or reflected from the high snowfields in mountain regions long after sunset. The particles produce a scattering effect upon the component parts of white light. The true alpenglow, which occurs long after sunset or long before sunrise, is caused by the backscattering of red sunlight by aerosols and fine dust particles low in the atmosphere. It is an afterglow caused by direct illumination of atmospheric particles by sunlight as it refracts and gets scattered through the Earth's atmosphere. The high-energy and high-frequency light is scattered out the most and the remaining low-energy, low-frequency reaches the observer in the horizon at twilight. The backscattering of this light further turns it pinkish-red. This period of time is referred to as the blue hour and is widely treasured by photographers and painters as it offers breathtaking imagery.The afterglow persists till the Earth's shadow (terminator line) takes over the sky of the observer as nightfall and the stars appear, with planet Venus being the brightest star visible in the night sky just opposite to the Belt of Venus at the anti-solar point.

text: An afterglow is a broad high arch of whitish or rosy light appearing in the

text: sky

text: due to very fine particles of

text: dust

text: suspended in the high regions of the

text: atmosphere

text: . An afterglow may appear above the highest

text: cloud

text: s in the hour of deepening

text: twilight

text: , or

text: reflected

text: from the high

text: snow

text: fields in

text: mountain

text: regions long after

text: sunset

text: . The particles produce a

text: scattering

text: effect upon the component parts of

text: white

text: light

text: . The true

text: alpenglow

text: , which occurs long after sunset or long before sunrise, is caused by the

text: backscattering

text: of red sunlight by

text: aerosols

text: and fine dust particles low in the atmosphere. It is an afterglow caused by

text: direct illumination

text: of atmospheric particles by sunlight as it

text: refracts

text: and gets

text: scattered

text: through the Earth's atmosphere. The

text: high-energy

text: and

text: high-frequency

text: light is

text: scattered

text: out the most and the remaining low-energy, low-frequency reaches the observer in the

text: horizon

text: at

text: twilight

text: . The backscattering of this light further turns it pinkish-red. This period of time is referred to as the

text: blue hour

text: and is widely treasured by

text: photographers

text: and

text: painters

text: as it offers breathtaking imagery.The afterglow persists till the

text: Earth's shadow

text: (terminator line) takes over the

text: sky

text: of the observer as nightfall and the stars appear, with planet

text: Venus

text: being the brightest star visible in the

text: night sky

text: just opposite to the

text: Belt of Venus

text: at the

text: anti-solar point

text: A new emerging type of concentrators which are still at the research stage are Luminescent solar concentrators, they are composed of luminescent plates either totally impregnated by luminescent species or fluorescent thin films on transparent plates. They absorb solar light which is converted to fluorescence guided to plate edges where it emerges in a concentrated form. The concentration factor is directly proportional to the plate surface and inversely proportional to the plate edges. Such arrangement allows to use small amounts of solar cells as a result of concentration of fluorescent light. The fluorescent concentrator is able to concentrate both direct and diffuse light which is especially important on cloudy days. They also don't need expensive Solar trackers.

text: A new emerging type of concentrators which are still at the research stage are

text: Luminescent solar concentrator

text: s, they are composed of luminescent plates either totally impregnated by luminescent species or fluorescent

text: thin films

text: on transparent plates. They absorb solar

text: light

text: which is converted to

text: fluorescence

text: guided to plate edges where it emerges in a concentrated form. The concentration factor is directly proportional to the plate surface and inversely proportional to the plate edges. Such arrangement allows to use small amounts of

text: solar cells

text: as a result of concentration of fluorescent light. The fluorescent concentrator is able to concentrate both direct and diffuse light which is especially important on cloudy days. They also don't need expensive

text: Solar tracker

text: s.

text: Helium–cadmium lasers are a common source of blue-ultraviolet laser light. They operate at either 325 or 422 nm in fluorescence microscopes and various laboratory experiments. Cadmium selenide quantum dots emit bright luminescence under UV excitation (He-Cd laser, for example). The color of this luminescence can be green, yellow or red depending on the particle size. Colloidal solutions of those particles are used for imaging of biological tissues and solutions with a fluorescence microscope.

text: Helium–cadmium lasers are a common source of blue-ultraviolet laser light. They operate at either 325 or 422 nm in

text: fluorescence microscope

text: s and various laboratory experiments. Cadmium selenide

text: quantum dot

text: s emit bright

text: luminescence

text: under UV excitation (He-Cd laser, for example). The color of this luminescence can be green, yellow or red depending on the particle size. Colloidal solutions of those particles are used for imaging of biological tissues and solutions with a

text: fluorescence microscope

text: Since not everyone is irritated by the same lighting sources, it is common for one person's light "pollution" to be light that is desirable for another. One example of this is found in advertising, when an advertiser wishes for particular lights to be bright and visible, even though others find them annoying. Other types of light pollution are more certain. For instance, light that accidentally crosses a property boundary and annoys a neighbor is generally wasted and pollutive light.

text: The pineconefish is yellow with distinct large scales outlined in black.  It has light-producing organs filled with luminescent bacteria on each side of the lower jaw the purpose of with is not known, but may help it to see at night or to attract prey.  The fish grows to 17 cm, but is more commonly found up to 12 cm.

text: With increasing depth underwater, sunlight is absorbed, and the amount of visible light diminishes. Because absorption is greater for long wavelengths (red end of the visible spectrum) than for short wavelengths (blue end of the visible spectrum), the colour spectrum is rapidly altered with increasing depth. White objects at the surface appear bluish underwater, and red objects appear dark, even black. Although light penetration will be less if water is turbid, in the very clear water of the open ocean less than 25% of the surface light reaches a depth of 10 m (33 feet). At 100 m (330 ft) the light present from the sun is normally about 0.5% of that at the surface.

text: With increasing depth underwater,

text: sunlight

text: is absorbed, and the amount of visible

text: light

text: diminishes. Because absorption is greater for long

text: wavelength

text: s (red end of the

text: visible spectrum

text: ) than for short wavelengths (blue end of the visible spectrum), the

text: colour spectrum

text: is rapidly altered with increasing depth. White objects at the surface appear bluish underwater, and red objects appear dark, even black. Although light penetration will be less if water is

text: turbid

text: , in the very clear water of the open ocean less than 25% of the surface light reaches a depth of 10 m (33 feet). At 100 m (330 ft) the light present from the sun is normally about 0.5% of that at the surface.

text: The luminous flux (or visible power) in a light source is defined by the photopic luminosity function. The following equation calculates the total luminous flux in a source of light:

text: A calculation of the MPE for ocular exposure takes into account the various ways light can act upon the eye. For example, deep-ultraviolet light causes accumulating damage, even at very low powers. Infrared light with a wavelength longer than about 1400 nm is absorbed by the transparent parts of the eye before it reaches the retina, which means that the MPE for these wavelengths is higher than for visible light. In addition to the wavelength and exposure time, the MPE takes into account the spatial distribution of the light (from a laser or otherwise). Collimated laser beams of visible and near-infrared light are especially dangerous at relatively low powers because the lens focuses the light onto a tiny spot on the retina. Light sources with a smaller degree of spatial coherence than a well-collimated laser beam, such as high-power LEDs, lead to a distribution of the light over a larger area on the retina. For such sources, the MPE is higher than for collimated laser beams. In the MPE calculation, the worst-case scenario is assumed, in which the eye lens focuses the light into the smallest possible spot size on the retina for the particular wavelength and the pupil is fully open. Although the MPE is specified as power or energy per unit surface, it is based on the power or energy that can pass through a fully open pupil (0.39 cm) for visible and near-infrared wavelengths. This is relevant for laser beams that have a cross-section smaller than 0.39 cm. The IEC-60825-1 and ANSI Z136.1 standards include methods of calculating MPEs.

text: A calculation of the MPE for ocular exposure takes into account the various ways light can act upon the eye. For example, deep-ultraviolet light causes accumulating damage, even at very low powers.

text: Infrared

text: light with a wavelength longer than about 1400 nm is absorbed by the transparent parts of the eye before it reaches the retina, which means that the MPE for these wavelengths is higher than for visible light. In addition to the wavelength and exposure time, the MPE takes into account the spatial distribution of the light (from a laser or otherwise). Collimated laser beams of visible and near-infrared light are especially dangerous at relatively low powers because the lens focuses the light onto a tiny spot on the retina. Light sources with a smaller degree of

text: spatial coherence

text: than a well-collimated laser beam, such as high-power

text: LED

text: s, lead to a distribution of the light over a larger area on the retina. For such sources, the MPE is higher than for collimated laser beams. In the MPE calculation, the worst-case scenario is assumed, in which the eye lens focuses the light into the smallest possible spot size on the retina for the particular wavelength and the

text: pupil

text: is fully open. Although the MPE is specified as power or energy per unit surface, it is based on the power or energy that can pass through a fully open pupil (0.39 cm) for visible and near-infrared wavelengths. This is relevant for laser beams that have a cross-section smaller than 0.39 cm. The IEC-60825-1 and ANSI Z136.1 standards include methods of calculating MPEs.

text: Optically stimulated luminescence dating is a related measurement method which replaces heating with exposure to intense light.  The sample material is illuminated with a very bright source of green or blue light (for quartz) or infrared light (for potassium feldspars).  Ultraviolet light emitted by the sample is detected for measurement.

text: Optically stimulated luminescence

text: dating is a related measurement method which replaces heating with exposure to intense light.  The sample material is illuminated with a very bright source of green or blue light (for

text: quartz

text: ) or

text: infrared light

text: (for

text: potassium feldspars

text: Ultraviolet light

text: emitted by the sample is detected for measurement.

text: In 1974, the glow was explained by R. J. van Zee and A. U. Khan. A reaction with oxygen takes place at the surface of the solid (or liquid) phosphorus, forming the short-lived molecules HPO and  that both emit visible light. The reaction is slow and only very little of the intermediates are required to produce the luminescence, hence the extended time the glow continues in a stoppered jar.

text: The service life of a RO is determined by the lifetime of the light source and the acceptable drift of the parameters of the photoresistor. A typical LED can operate for 10,000 hours, after which its parameters slightly degrade. Its lifetime can be prolonged by limiting the controlling current to half of the maximum value. ROs based on incandescent lamps typically fail after about 20,000 hours, due to the burnout of the spiral, and are more prone to overheating.

text: The common symbol for inventiveness, the light bulb, is a perfect example. The first incandescent light bulb was invented by British chemist Sir Humphry Davy in 1802. Many subsequent inventors improved Davy's invention prior to the successful commercialization of electric lighting by Thomas Edison in 1880, 78 years later. Electric lighting continued to be developed. Edison's carbon filament light bulb was made obsolete by the tungsten filament light bulb, invented in 1904 by Sándor Just and Franjo Hanaman. It is this that forms the popular conception of a light bulb, though there are other major forms of lighting. The principle of fluorescent lights was known since 1845, and various inventors, including Edison and Nikola Tesla worked on them without commercial success. Various improvements were made by many other inventors, until General Electric introduced "fluorescent lumiline lamps" commercially in 1938, first available to the public at the 1939 World's Fair. LED lamps also have a long history, with the first light-emitting diode (LED) invented in 1927 by Oleg Losev. LEDs were initially of low brightness, and have been used as indicator lamps and seven-segment displays since 1968. It wasn't until the development of high efficiency blue LEDs by Shuji Nakamura in the 1980s that white LEDs for lighting applications became practical. Although higher cost than incandescent light bulbs, LEDs have higher efficiency and longer life and may finally displace light bulbs in general lighting applications. In each case, more than 50 years passed between the initial invention and commercial success in general lighting applications.

text: The common symbol for inventiveness, the light bulb, is a perfect example. The first

text: incandescent light bulb

text: was invented by British

text: chemist

text: Sir Humphry Davy

text: in 1802. Many subsequent inventors improved Davy's invention prior to the successful commercialization of electric lighting by

text: Thomas Edison

text: in 1880, 78 years later. Electric lighting continued to be developed. Edison's carbon filament light bulb was made obsolete by the tungsten filament light bulb, invented in 1904 by

text: Sándor Just

text: and

text: Franjo Hanaman

text: . It is this that forms the popular conception of a light bulb, though there are other major forms of lighting. The principle of

text: fluorescent lights

text: was known since 1845, and various inventors, including Edison and

text: Nikola Tesla

text: worked on them without commercial success. Various improvements were made by many other inventors, until

text: General Electric

text: introduced "fluorescent lumiline lamps" commercially in 1938, first available to the public at the

text: 1939 World's Fair

text: LED lamps

text: also have a long history, with the first

text: light-emitting diode

text: (LED) invented in 1927 by

text: Oleg Losev

text: . LEDs were initially of low brightness, and have been used as indicator lamps and

text: seven-segment display

text: s since 1968. It wasn't until the development of high efficiency blue LEDs by

text: Shuji Nakamura

text: in the 1980s that white LEDs for lighting applications became practical. Although higher cost than incandescent light bulbs, LEDs have higher efficiency and longer life and may finally displace light bulbs in general lighting applications. In each case, more than 50 years passed between the initial invention and commercial success in general lighting applications.

text: Suitable optical designs trap light emitted by the luminescent material in all directions, redirecting it so that little escapes the photovoltaic converters. Redirection techniques include internal reflection, refractive index gradients and where suitable, diffraction. In principle such LSCs can use light from cloudy skies and similar diffuse sources that are of little use for powering conventional solar cells or for concentration by conventional optical reflectors or refractive devices.

text: Suitable optical designs trap light emitted by the luminescent material in all directions, redirecting it so that little escapes the

text: photovoltaic converters

text: . Redirection techniques include

text: internal reflection

text: refractive index

text: gradients and where suitable,

text: diffraction

text: . In principle such LSCs can use light from cloudy skies and similar diffuse sources that are of little use for powering conventional solar cells or for concentration by conventional optical reflectors or refractive devices.

text: The absorption of energy followed by the emission of light is often described by the term luminescence. The exact term  used is based on the energy source responsible for the luminescence as in color-change phenomena.

text: The absorption of energy followed by the emission of light is often described by the term

text: luminescence

text: . The exact term  used is based on the energy source responsible for the luminescence as in color-change phenomena.

text: Light can have a variety of effects on textiles over time.  In some cases, it may contribute to fading or discoloration, but of more concern is the damage which the fibers may suffer under prolonged exposure to non-visible light, such as ultraviolet and infrared lighting.  Ideally, textiles should be stored or displayed in as little light as possible, and preferably in total darkness.  However, as this is impractical for display and care of the piece, knowing the limits of lighting as well as the safest amounts of lighting, become important.

text: Light

text: can have a variety of effects on textiles over time.  In some cases, it may contribute to fading or discoloration, but of more concern is the damage which the fibers may suffer under prolonged exposure to non-visible light, such as

text: ultraviolet

text: and

text: infrared

text: lighting.  Ideally, textiles should be stored or displayed in as little light as possible, and preferably in total darkness.  However, as this is impractical for display and care of the piece, knowing the limits of lighting as well as the safest amounts of lighting, become important.

text: Three Women is one of Umberto Boccioni’s paintings that portrayed evidence of his transformation from the divisionism style to the futurism style. Three Women is a painting that portrays raw emotion, with calmness and intimacy. The faces of the figures in the painting are dressed with melancholy tones. This painting is categorized as a divisionism painting, however there exists a futuristic style within it. The way that the light enters the room and affects the figures is an example of how this painting contains both divisionism and futurism. A characteristic of futurism lies in the varying and visible strokes as well. This aspect of futurism is extremely evident in this painting; it is seen in the women’s dresses, the women’s hair, the luminescence, the walls in the background, the bed, and the women’s faces and skin.  Also, the luminescence mentioned above, according to Maurizio Calvesi, may be in relation to Einstein’s concepts of the physical properties of light, adding yet another futuristic aspect to Three Women, he says in 1967. The significance of Boccioni’s Three Women isn’t necessarily the painting itself, but lies in what the painting represents. According to Coen, it “marks a moment of transition in the artist’s work, the bridge from the suburbs of Milan to the idealistic vision of The City Rises”.

text: Black light paints and inks are commonly used in the production of black light posters. Under daylight, the poster may or may not be vibrant in color, but under black light (with little or no visible light present), the effect produced can be psychedelic. The inks are normally highly sensitive to direct sunlight and other powerful light sources. The fluorescent dyes cause a chemical reaction when exposed to high intensity light sources (HILS) and the visual result is a fading in the colors of the inks. With paper, significant visible change in the color saturation can typically be observed within 45 minutes to one hour of exposure to the HILS. To date, there is no absolute method to prevent this phenomenon, although certain laminations, lacquer coatings and glass or plastic protective sheets can effectively slow the fading characteristics of the dyes.

text: Black light paints and

text: inks

text: are commonly used in the production of

text: black light posters

text: . Under daylight, the poster may or may not be vibrant in color, but under black light (with little or no visible light present), the effect produced can be

text: psychedelic

text: . The inks are normally highly sensitive to direct sunlight and other powerful light sources. The fluorescent dyes cause a chemical reaction when exposed to high intensity light sources (HILS) and the visual result is a fading in the colors of the inks. With paper, significant visible change in the color saturation can typically be observed within 45 minutes to one hour of exposure to the HILS. To date, there is no absolute method to prevent this phenomenon, although certain laminations, lacquer coatings and glass or plastic protective sheets can effectively slow the fading characteristics of the dyes.

text: Reflectivity is light reflected from a source to a surface and  returned to its original source.  For traffic signs and vehicle operators, the light source is a vehicle’s headlights, where the light is sent to the traffic sign face and then returned to the vehicle operator. Traffic signs are manufactured with retroreflective sheeting so that the traffic sign is visible at night. Reflective sign faces are manufactured with glass beads or prismatic reflectors imbedded in the sheeting so that the face reflects light, therefore making the sign appear more bright and visible to the vehicle operator. According to the National Highway Traffic Safety Administration (NHTSA), the Traffic Safety Facts 2000 publication states the fatal crash rate is 3-4 times more likely during nighttime crashes than daytime incidents.

text: Reflectivity is light reflected from a source to a surface and  returned to its original source.  For traffic signs and vehicle operators, the light source is a vehicle’s headlights, where the light is sent to the traffic sign face and then returned to the vehicle operator. Traffic signs are manufactured with retroreflective sheeting so that the traffic sign is visible at night. Reflective sign faces are manufactured with glass beads or prismatic reflectors imbedded in the sheeting so that the face reflects light, therefore making the sign appear more bright and visible to the vehicle operator. According to the

entity_name: National Highway Traffic Safety Administration

text: National Highway Traffic Safety Administration

text: (NHTSA), the Traffic Safety Facts 2000 publication states the fatal crash rate is 3-4 times more likely during nighttime crashes than daytime incidents.

text: Luminescence is the first album from the British electropop band Neon Highwire. It was released on Health Bomber.

text: Luminescence is the first

text: album

text: from the

text: British

text: electropop

text: band

text: Neon Highwire

text: . It was released on

text: Health Bomber

text: Illumination (2007) is an album by the American ambient musician Robert Rich.  This CD is published as a companion piece to Michael Somoroff’s installation Illumination I originally created for the famed Rothko Chapel, on the occasion of the installation’s move to The Aldrich Contemporary Art Museum in Ridgefield, CT as the audio track to Somoroff’s Illumination, a multimedia installation at BravinLee Programs in Chelsea, N.Y.C. during the summer of 2007.

text: Illumination (2007) is an album by the

text: American

text: ambient

text: musician

text: Robert Rich

text: .  This CD is published as a companion piece to Michael Somoroff’s installation Illumination I originally created for the famed Rothko Chapel, on the occasion of the installation’s move to The Aldrich Contemporary Art Museum in Ridgefield, CT as the audio track to Somoroff’s Illumination, a multimedia installation at

text: BravinLee Programs

text: in Chelsea, N.Y.C. during the summer of 2007.

text: The heat output of any resistance device, such as an electric space heater, is equal to the true power consumption, which is an increasing function of the applied voltage. If the resistance stays constant, power consumption is proportional to the square of the applied voltage. Therefore, a significant reduction of heat output will occur with a relatively small reduction in voltage. An incandescent lamp will dim due to lower heat creation in the filament, as well as lower conversion of heat to light. Generally speaking, no damage will occur but functionality will be impaired.

text: The heat output of any resistance device, such as an electric

text: space heater

text: , is equal to the true power consumption, which is an increasing function of the applied voltage. If the resistance stays constant, power consumption is proportional to the square of the applied voltage. Therefore, a significant reduction of heat output will occur with a relatively small reduction in voltage. An

text: incandescent lamp

text: will dim due to lower heat creation in the filament, as well as lower conversion of heat to light. Generally speaking, no damage will occur but functionality will be impaired.

text: The analysis of HsV in turn has led to the study of objects called Voowerpjes (see HsV article) and  Green bean galaxies. A picture of NGC 5972, a small Voorwerpje, taken by the Hubble Space Telescope (HST), is to the right. This was imaged as part of a study of 8 Voorwerpjes. It shows the galaxy NGC 5972, which once had an Active galactic nucleus which has turned off ('off duty'). Only visible for a few tens of thousands of years, the greenish gas is still illuminated by light or ionization from NGC 5972.

text: The analysis of HsV in turn has led to the study of objects called Voowerpjes (see HsV article) and

text: Green bean galaxies

text: . A picture of NGC 5972, a small Voorwerpje, taken by the

text: Hubble Space Telescope

text: (HST), is to the right. This was imaged as part of a study of 8 Voorwerpjes. It shows the galaxy NGC 5972, which once had an

text: Active galactic nucleus

text: which has turned off ('off duty'). Only visible for a few tens of thousands of years, the greenish gas is still illuminated by light or ionization from NGC 5972.

text: Lighting engineers for years have had to contend with glare, the visual discomfort caused by direct lighting. They developed Equivalent Sphere Illumination to measure it. They then developed Visual Comfort Probability.  High values of comfort imply more diffuse lighting; the light comes from many directions.  That concept has never been seriously applied to sound. Most people continually experience ambient sound and are seldom aware of it if the level is reasonable; it is often referred to as background sound.  That is because the sound they hear comes from many sources, the sound field is diffuse.  This concept applies to sound masking as well. Experience has shown that when an office occupant can point at the source of the sound masking (the sound field is more direct), acceptance is diminished.  Diffusion of masking sound is best accomplished by the presence of intervening sound attenuating materials, such as ceilings and floors.  Of the locations listed above, under floor masking creates the best diffusion.

text: The only light source in the deep sea, marine animals give off visible light energy called bioluminescence, a subset of chemiluminescence. This is the chemical reaction in which chemical energy is converted to light energy. It is estimated that 90% of deep-sea animals produce some sort of bioluminescence. Considering that a large proportion of the visible light spectrum is absorbed before reaching the deep sea, most of the emitted light from the sea-animals is blue and green. However, some species may emit a red and infrared light, and there has even been a genus that is found to emit yellow bioluminescence. The organ that is responsible for the emission of bioluminescence is known as photophores. This type is only present in squid and fish, and is used to illuminate their ventral surfaces, which disguise their silhouettes from predators. The uses of the photophores in the sea-animals differ, such as lenses for controlling intensity of color, and the intensity of the light produced. Squids have both photophores and chromatophores which controls both of these intensities. Another thing that is responsible for the emission of bioluminescence, which is evident in the bursts of light that jellyfish emit, start with a luciferin (a photogen) and ends with the light emitter (a photagogikon.) Luciferin, luciferase, salt, and oxygen react and combine to create a single unit called photo-proteins, which can produce light when reacted with another molecule such as Ca+. Jellyfish use this as a defense mechanism; when a smaller predator is attempting to devour a jellyfish, it will flash its lights, which would therefore lure a larger predator and chase the smaller predator away. It is also used as mating behavior.

text: The only light source in the deep sea, marine animals give off visible light energy called

text: bioluminescence

text: , a subset of

text: chemiluminescence

text: . This is the chemical reaction in which chemical energy is converted to light energy. It is estimated that 90% of deep-sea animals produce some sort of bioluminescence. Considering that a large proportion of the visible light spectrum is absorbed before reaching the deep sea, most of the emitted light from the sea-animals is blue and green. However, some species may emit a red and infrared light, and there has even been a genus that is found to emit yellow bioluminescence. The organ that is responsible for the emission of bioluminescence is known as photophores. This type is only present in squid and fish, and is used to illuminate their ventral surfaces, which disguise their silhouettes from predators. The uses of the photophores in the sea-animals differ, such as lenses for controlling intensity of color, and the intensity of the light produced. Squids have both photophores and chromatophores which controls both of these intensities. Another thing that is responsible for the emission of bioluminescence, which is evident in the bursts of light that

text: jellyfish

text: emit, start with a luciferin (a photogen) and ends with the light emitter (a photagogikon.) Luciferin, luciferase, salt, and oxygen react and combine to create a single unit called photo-proteins, which can produce light when reacted with another molecule such as Ca+. Jellyfish use this as a defense mechanism; when a smaller predator is attempting to devour a jellyfish, it will flash its lights, which would therefore lure a larger predator and chase the smaller predator away. It is also used as mating behavior.

text: Electromagnetic radiation is characterized by its wavelength (or frequency) and its intensity. When the wavelength is within the visible spectrum (the range of wavelengths humans can perceive, approximately from 390 nm to 700 nm), it is known as "visible light".

text: Electromagnetic radiation

text: is characterized by its

text: wavelength

text: (or

text: frequency

text: ) and its

text: intensity

text: . When the wavelength is within the visible spectrum (the range of wavelengths humans can perceive, approximately from 390

text: nm

text: to 700 nm), it is known as "visible light".

text: I am in a big mass of some very small particles, they're brilliantly lit up like they're luminescent. I never saw anything like it. They round a little: they're coming by the capsule and they look like little stars. A whole shower of them coming by. They swirl around the capsule and go in front of the window and they're all brilliantly lighted. Glenn started banging the capsule wall and watched the "fireflies" come off, just as Alan Shepard did.

text: If an incandescent lamp is operated on a low-frequency current, the filament cools on each half-cycle of the alternating current, leading to perceptible change in brightness and flicker of the lamps; the effect is more pronounced with arc lamps, and the later mercury-vapor and fluorescent lamps.

text: If an incandescent lamp is operated on a low-frequency current, the filament cools on each half-cycle of the alternating current, leading to perceptible change in brightness and flicker of the lamps; the effect is more pronounced with

text: arc lamp

text: s, and the later

text: mercury-vapor

text: and

text: fluorescent

text: lamps.

text: At the time of the invention of his revolutionary illumination scheme as a graduate student at the University of Giessen, Köhler was working on overcoming problems with microphotography. Microscopes were illuminated by gas lamps, mirrors or other primitive light sources, resulting in an uneven specimen illumination unsuited for producing good quality photomicrographs using the slow-speed emulsions available at the time. Over the course of his work for his doctorate degree, Köhler developed a microscope configuration that allowed for an evenly illuminated field of view and reduced optical glare from the light source. It involved a collector lens for the lamp that allowed the light source to be focused on the front aperture of the condenser. This in turn allowed the condenser to be focused on the specimen using a field diaphragm and condenser focus control. This superior illumination scheme is still widely used in modern microscopes and forms the basis for phase contrast, differential interference contrast, epifluorescence, and confocal microscopy.

text: At the time of the invention of his revolutionary illumination scheme as a graduate student at the University of Giessen, Köhler was working on overcoming problems with microphotography. Microscopes were illuminated by

text: gas lamp

text: s, mirrors or other primitive light sources, resulting in an uneven specimen illumination unsuited for producing good quality

text: photomicrograph

text: s using the slow-speed

text: emulsion

text: s available at the time. Over the course of his work for his doctorate degree, Köhler developed a microscope configuration that allowed for an evenly illuminated field of view and reduced optical glare from the light source. It involved a collector lens for the lamp that allowed the light source to be focused on the front

text: aperture

text: of the

text: condenser

text: . This in turn allowed the condenser to be focused on the specimen using a field

text: diaphragm

text: and condenser focus control. This superior illumination scheme is still widely used in modern microscopes and forms the basis for

text: phase contrast

entity_name: Differential interference contrast microscopy

text: differential interference contrast

text: epifluorescence

text: , and

text: confocal microscopy

text: Light, or visible light, is a very narrow range of electromagnetic radiation of a wavelength that is visible to the human eye, or 380–750 nm which equates to a frequency range of 790 to 400 THz respectively. More broadly, physicists use the term "light" to mean electromagnetic radiation of all wavelengths, whether visible or not.

text: Luminescence is the first EP from the British electropop band Neon Highwire. It was released on Health Bomber.

text: Luminescence is the first

text: EP

text: from the

text: British

text: electropop

text: band

text: Neon Highwire

text: . It was released on

text: Health Bomber

text: The Tungsten halogen curing light, also known as simply “halogen curing light” is the most frequent polymerization source used in dental offices.    In order for the light to be produced, an electric current flows through a thin tungsten filament, which functions as a resistor.  This resistor is then “heated to temperatures of about 3,000 Kelvin, it becomes incandescent and emits infrared and electromagnetic radiation in the form of visible light”.   It provides a blue light of about 400 and 500 nm, with an intensity of 400- 600 mW cm^-2.  This type of curing light however has certain drawbacks, the first of which is the high temperatures that the filament generates.  This requires that the curing light have a ventilating fan installed in order to “force airflow through slots in the casing”.  This requires the curing light to be larger, in order to house the fan.  The fan generates a sound that may disturb some patients, and the wattage of the bulb is such (e.g. 80W) these curing lights must be plugged into a power source, that is, they are not cordless. Furthermore, this light requires frequent monitoring and replacement of the actual curing light bulb because of the high temperatures that are reached.  (For example, one model uses a bulb with an estimated life of 50 hours which would require annual replacement, assuming 12 minutes' use per day, 250 days per year.)  Also, the time needed to fully cure the material is much more than the LED curing light.

text: The Tungsten halogen curing light, also known as simply “halogen curing light” is the most frequent polymerization source used in dental offices.    In order for the light to be produced, an electric current flows through a thin

text: tungsten filament

text: , which functions as a

text: resistor

text: Lighting or illumination is the deliberate use of light to achieve a practical or aesthetic effect. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting (using windows, skylights, or light shelves) is sometimes used as the main source of light during daytime in buildings.  This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings.  Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.

text: Lighting or illumination is the deliberate use of

text: light

text: to achieve a practical or aesthetic effect. Lighting includes the use of both artificial

text: light source

text: s like lamps and light fixtures, as well as natural illumination by capturing

text: daylight

text: Daylighting

text: (using windows, skylights, or light shelves) is sometimes used as the main source of light during daytime in buildings.  This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings.  Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.

text: Troika wanted to make a 3D game, but was uncertain whether to build a new game engine or license an existing one and whether to use first- or third-person. At that time, the Source game engine was being built by Valve Corporation. Valve employee Scott Lynch approached Troika about using the engine, and it was the first external team to use it. Troika chose Source for its facial animation and lip-synching system, since it wanted players to speak to the characters face-to-face. Since the engine was in development with Bloodlines and Valve's own Half-Life 2, Troika was working with unfamiliar code and tools, forcing it to write its own code to compensate for the unfinished engine, and with only a single source for technical support. Troika developed a lighting system to create distinctive, moody illumination for the nighttime setting, a particle system for the special effects accompanying the vampire Disciplines, and a cloth system for clothing flow. Source lacked its later artificial intelligence (AI) coding, and Troika's code worked poorly with the Source engine.

text: Troika wanted to make a

text: 3D game

text: , but was uncertain whether to build a new game engine or license an existing one and whether to use first- or third-person. At that time, the

text: Source

text: game engine was being built by

text: Valve Corporation

text: . Valve employee Scott Lynch approached Troika about using the engine, and it was the first external team to use it. Troika chose Source for its facial animation and lip-synching system, since it wanted players to speak to the characters face-to-face. Since the engine was in development with Bloodlines and Valve's own

text: Half-Life 2

text: , Troika was working with unfamiliar code and tools, forcing it to write its own code to compensate for the unfinished engine, and with only a single source for technical support. Troika developed a lighting system to create distinctive, moody illumination for the nighttime setting, a particle system for the special effects accompanying the vampire Disciplines, and a cloth system for clothing flow. Source lacked its later

text: artificial intelligence

text: (AI) coding, and Troika's code worked poorly with the Source engine.

text: Critical illumination or Nelsonian illumination is a method of specimen illumination used for transmitted and reflected light (trans- and epi-illuminated) optical microscopy. Critical illumination focuses an image of a light source on to the specimen for bright illumination. Critical illumination generally has problems with evenness of illumination as an image of the illumination source (for example a halogen lamp filament) is visible in the resulting image. Köhler illumination has largely replaced critical illumination in modern scientific light microscopy although it requires additional optics which less expensive and simpler light microscopes may not have.

text: Critical illumination or Nelsonian illumination is a method of

text: specimen

text: illumination

text: optical microscopy

text: . Critical illumination focuses an image of a light source on to the specimen for bright illumination. Critical illumination generally has problems with evenness of illumination as an image of the illumination source (for example a halogen lamp filament) is visible in the resulting image.

text: Köhler illumination

text: has largely replaced critical illumination in modern scientific light microscopy although it requires additional optics which less expensive and simpler light microscopes may not have.

text: The goal was to obtain the greatest imaging area in the smallest cylindrical volume using a consumer flatbed scanner.  Typical flatbed scanners image an area of about 220 x 300 mm (660 cm), so a system had to be found which could be reconfigured to fit inside a sealed transparent capsule.  There are two basic imaging methods in modern flatbed scanners.  From the 1980s to the late-1990s the market was dominated by systems that could capture an image from any depth of field.  Most such digital imaging devices used a Charge-Coupled Device (CCD) array.  In a CCD, discrete dots of photosensitive material produce a specific charge based on the intensity of light hitting it.  A CCD does not detect colour.  In this technology, a scene is illuminated, a narrow band of reflected light from the scene passes through a slit (to eliminate light coming from other directions), is then concentrated by an array of mirrors (typically folded into a box) into a prism typically a few centimetres in length.  The prism splits the light into its constituent colours.  Small CCD arrays are carefully placed at the point where the primary colours are sharply focused.  The separate colour intensities are combined to composite values and recorded by the computer (or scanner electronic assemblies) as a line of pixels.  The moving scan head then advances a short distance to gather the next line of the scene.  Thus resolution in one axis is determined by CCD array size and focused optics, while the other axis’ resolution is determined by the smallest reliable step the scan head advancing motor can make.  The optical assemblies of this type of scanner are fairly robust to vibration, but the traditional light source (a cold cathode tube of balanced colour temperature) is not.  It was therefore replaced with an array of solid-state white light emitting diodes (LEDs).  Another advantage of this replacement is that the sources could be alternated between white light and ultraviolet (UV) of about 370 nm wavelength.  This UV light source allowed detection of visibly fluorescing materials (typically tracer minerals or hydrocarbons) by the prototype.

text: Commonly called 'light bulbs', lamps are the removable and replaceable part of a light fixture, which converts electrical energy into electromagnetic radiation. While lamps have traditionally been rated and marketed primarily in terms of their power consumption, expressed in watts, proliferation of lighting technology beyond the incandescent light bulb has eliminated the correspondence of wattage to the amount of light produced. For example, a 60 W incandescent light bulb produces about the same amount of light as a 13 W compact fluorescent lamp. Each of these technologies has a different efficacy in converting electrical energy to visible light. Visible light output is typically measured in lumens. This unit only quantifies the visible radiation, and excludes invisible infrared and ultraviolet light. A wax candle produces on the close order of 13 lumens, a 60 watt incandescent lamp makes around 700 lumens, and a 15-watt compact fluorescent lamp produces about 800 lumens, but actual output varies by specific design. Rating and marketing emphasis is shifting away from wattage and towards lumen output, to give the purchaser a directly applicable basis upon which to select a lamp.

text: Commonly called 'light bulbs',

text: lamps

text: are the removable and replaceable part of a light fixture, which converts electrical energy into

text: electromagnetic radiation

text: . While lamps have traditionally been rated and marketed primarily in terms of their power consumption, expressed in

text: watt

text: s, proliferation of lighting technology beyond the

text: incandescent light bulb

text: has eliminated the correspondence of wattage to the amount of light produced. For example, a 60 W incandescent light bulb produces about the same amount of light as a 13 W

text: compact fluorescent lamp

text: . Each of these technologies has a different

text: efficacy

text: in converting electrical energy to

text: visible light

text: . Visible light output is typically measured in

text: lumen

text: s. This unit only quantifies the visible radiation, and excludes invisible infrared and ultraviolet light. A wax candle produces on the close order of 13 lumens, a 60 watt incandescent lamp makes around 700 lumens, and a 15-watt compact fluorescent lamp produces about 800 lumens, but actual output varies by specific design. Rating and marketing emphasis is shifting away from wattage and towards lumen output, to give the purchaser a directly applicable basis upon which to select a lamp.

text: Often when a photon is absorbed, the system is excited in the corresponding excited state, then it relaxes in an intermediate lower energy state, with a "non-radiative relaxation" (a relaxation that doesn't involve the emission of a photon, but e.g. involves the emission of vibrational energy) and then there is the emission of a photon with a lower energy than the absorbed one, because of the relaxation from the intermediate, lower energy state to the "ground state". Usually the strongest luminescence of the material is from the lower levels to the ground state. This process is called fluorescence. For instance, in semiconductors, most of the light emitted is at the frequency corresponding to the bandgap energy, i.e. from the bottom of the conduction band to the top of the valence band. In such systems, more light absorbed by the material, results in more electrons decaying non-radiatively to the lower states, and more luminescence in the emission wavelength.

text: Often when a photon is absorbed, the system is excited in the corresponding excited state, then it relaxes in an intermediate lower energy state, with a "non-radiative relaxation" (a relaxation that doesn't involve the emission of a photon, but e.g. involves the emission of vibrational energy) and then there is the emission of a photon with a lower energy than the absorbed one, because of the relaxation from the intermediate, lower energy state to the "ground state". Usually the strongest luminescence of the material is from the lower levels to the ground state. This process is called

text: fluorescence

text: . For instance, in

text: semiconductors

text: , most of the light emitted is at the frequency corresponding to the bandgap energy, i.e. from the bottom of the conduction band to the top of the valence band. In such systems, more light absorbed by the material, results in more electrons decaying non-radiatively to the lower states, and more luminescence in the emission wavelength.

text: The light characteristic shown is four white flashes every twenty seconds Fl.(4)W. 20s,  only visible in the sector 120°-320°. The light source is a 12 Volt 50 Watt tungsten-halogen lamp, fed from the Mains electricity, providing a light intensity of 55,000 cd, visible for .

text: The

text: light characteristic

text: shown is four white flashes every twenty seconds Fl.(4)W. 20s,  only visible in the sector 120°-320°. The light source is a 12

text: Volt

text: Watt

text: tungsten-halogen lamp

text: , fed from the

text: Mains electricity

text: , providing a light intensity of 55,000

text: cd

text: , visible for .

text: The city's newly-constructed football venue, U.S. Bank Stadium, faced a similar controversy; the Minneapolis offices of Wells Fargo, a bank that competes with naming rights sponsor U.S. Bank, are located within the vicinity of the stadium. In December 2015, the Minnesota Vikings (who are the main tenant of the stadium) sued Wells Fargo for beginning the process of installing an illuminated sign on the rooftop of their building, which violated an agreement with the bank that it would only install "non-mounted," non-illuminated signage on its building, such as letters painted directly onto the roof. The sign would be visible in overhead views of U.S. Bank Stadium (such as camera shots during event telecasts), which the Vikings described as being a "photobombing" of the "iconic" facility. After the original agreement was reached, Wells Fargo had asked the team to allow it to install "raised, illuminated lettering. mounted on beams more than a foot above the roof rather than painted on the roof as agreed upon". The bank threatened to light the entire rooftops of its offices if the Vikings chose to deny the requested change. On June 23, 2016, Judge Donovan W. Frank ruled in favor of the Vikings, and ordered Wells Fargo to remove the raised, illuminated signage.

text: The city's newly-constructed football venue,

text: U.S. Bank Stadium

text: , faced a similar controversy; the Minneapolis offices of

text: Wells Fargo

text: , a bank that competes with naming rights sponsor

text: U.S. Bank

text: , are located within the vicinity of the stadium. In December 2015, the

text: Minnesota Vikings

text: (who are the main tenant of the stadium) sued Wells Fargo for beginning the process of installing an illuminated sign on the rooftop of their building, which violated an agreement with the bank that it would only install "non-mounted," non-illuminated signage on its building, such as letters painted directly onto the roof. The sign would be visible in overhead views of U.S. Bank Stadium (such as camera shots during event telecasts), which the Vikings described as being a "

text: photobombing

text: " of the "iconic" facility. After the original agreement was reached, Wells Fargo had asked the team to allow it to install "raised, illuminated lettering. mounted on beams more than a foot above the roof rather than painted on the roof as agreed upon". The bank threatened to light the entire rooftops of its offices if the Vikings chose to deny the requested change. On June 23, 2016, Judge

text: Donovan W. Frank

text: ruled in favor of the Vikings, and ordered Wells Fargo to remove the raised, illuminated signage.

text: Above infrared in frequency comes visible light. The Sun emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light. By definition, visible light is the part of the EM spectrum the human eye is the most sensitive to. Visible light (and near-infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. This action allows the chemical mechanisms that underlie human vision and plant photosynthesis. The light that excites the human visual system is a very small portion of the electromagnetic spectrum. A rainbow shows the optical (visible) part of the electromagnetic spectrum; infrared (if it could be seen) would be located just beyond the red side of the rainbow with ultraviolet appearing just beyond the violet end.

text: Above infrared in frequency comes

text: visible light

text: . The

text: Sun

text: emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light. By definition, visible light is the part of the EM spectrum the

text: human eye

text: is the most sensitive to. Visible light (and near-infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. This action allows the chemical mechanisms that underlie human vision and plant photosynthesis. The light that excites the human

text: visual system

text: is a very small portion of the electromagnetic spectrum. A

text: rainbow

text: shows the optical (visible) part of the electromagnetic spectrum; infrared (if it could be seen) would be located just beyond the red side of the rainbow with

text: ultraviolet

text: appearing just beyond the violet end.

text: Trees, buildings and enemies are drawn in filled light-sourced polygons. Shadows of the lander and enemies are projected vertically onto the ground, which does not cater for landscape curvature but is fast. Consequently, shadows are not shown on other scenery.<ref name='TMU 1987-11'/> The shadows allow the player to follow movements of enemy craft by their shadows, even when they are not visible on the screen. In !Virus, there is no light-sourcing. The game also provides particle system effects to depict the thrust from the lander, explosions, the virus spreading over the landscape, and assorted other phenomena such as splashes when shots strike water, and puffs of dust when they strike land. At altitude, when the ground cannot be seen, dust particles in the air give the impression of movement and speed.

text: Trees, buildings and enemies are drawn in filled light-sourced

text: polygons

text: . Shadows of the lander and enemies are projected vertically onto the ground, which does not cater for landscape curvature but is fast. Consequently, shadows are not shown on other scenery.<ref name='TMU 1987-11'/> The shadows allow the player to follow movements of enemy craft by their shadows, even when they are not visible on the screen. In !Virus, there is no light-sourcing. The game also provides

text: particle system

text: effects to depict the thrust from the lander, explosions, the virus spreading over the landscape, and assorted other phenomena such as splashes when shots strike water, and puffs of dust when they strike land. At altitude, when the ground cannot be seen, dust particles in the air give the impression of movement and speed.

text: Kila MandirSituated in Shivaji Road, in the heart of the town. The soldiers of Ramgarh  Battalion had a barricade here, the temple was surrounded and secured by deep canyons filled with water, which was connected to the temple underground now named as Bijulia Talab (lake) which also served as water source for British camp. The Gadh (Kila) of Ramgarh regime  was situated nearly 3 km. was on the bank of River Damodar. Famous 'Garh' was signaled from here by the means of Mashal (a source of light). The 'Garh' is still visible from the top of Kila Mandir.

text: Another fundamental concept of all AFM is the feedback loop. The feedback loop is particularly important in non-contact AFM techniques, particularly in pc-AFM. As previously mentioned, in non-contact mode the cantilever is stationary and the tip does not come into physical contact with the sample surface. The cantilever behaves as a spring and oscillates at its resonance frequency. Topological variance causes the spring-like oscillations of the cantilever to change amplitude and phase in order to prevent the tip from colliding with sample topographies. The non-contact feedback loop is used to control that changes in the oscillations of the cantilever. The application of AFM on non-conducting samples (c-AFM) has in recent years evolved into the modification used for analysis of morphologies on the local scale, particularly morphologies at heterojunctions of multilayered samples. Photoconductive atomic force microscopy (pc-AFM) is particularly prevalent in the development of organic photovoltaic devices (OPV). The fundamental modification of c-AFM to pc-AFM is the addition of an illumination source and an inverted microscope that focuses the laser to a nanometer-scale point directly underneath the conductive AFM tip. The main concept of the illumination laser point is that it must be small enough to fit within the confines of ultra-thin films. These characteristics are achieved by using a monochromatic light source and a laser filter. In the OPV application, applying the illumination laser to the confines of ultra-thin films is further assisted by the recent development of the bulk heterojunction (BHJ) mixture of electron donating and accepting material in the film.The combination of the conductive tip and illumination laser provides photocurrent images with vertical resolutions in the range of 0 to 10 pA when overlaid with the topographical data obtained. Also unique to this modification are the spectra data gathered by comparing the current between the tip and sample to a variety of parameters including: laser wavelength, applied voltage and light intensity. The pc-AFM technique was also reported to detect local surface oxidation at a vertical resolution of 80 nm.

text: Another fundamental concept of all AFM is the

text: feedback loop

text: The facade of the structure is illuminated by hundreds of programmable color changing LED and metal halide luminaires with design work by Gabler-Youngston Architectural Lighting Design.  The facade lighting system provides various shows and effects.  Highly visible over the east corner of Bank of America Stadium, the lighting show is used during key moments of sporting events played there. For example, if the Carolina Panthers are playing it may light up blue. For the 2011 ACC Championship game, the building displayed orange and purple lighting for Clemson University and red and orange for Virginia Tech.

text: The facade of the structure is illuminated by hundreds of programmable color changing LED and metal halide luminaires with design work by Gabler-Youngston Architectural Lighting Design.  The facade lighting system provides various shows and effects.  Highly visible over the east corner of

text: Bank of America Stadium

text: , the lighting show is used during key moments of sporting events played there. For example, if the

text: Carolina Panthers

text: are playing it may light up blue. For the 2011 ACC Championship game, the building displayed orange and purple lighting for

text: Clemson University

text: and red and orange for

text: Virginia Tech

text: Visible light is an electromagnetic wave, consisting of oscillating electric and magnetic fields traveling through space. The frequency of the wave determines its color:  is red light,  is violet light, and between these (in the range 4-) are all the other colors of the visible spectrum. An electromagnetic wave can have a frequency less than , but it will be invisible to the human eye; such waves are called infrared (IR) radiation. At even lower frequency, the wave is called a microwave, and at still lower frequencies it is called a radio wave. Likewise, an electromagnetic wave can have a frequency higher than , but it will be invisible to the human eye; such waves are called ultraviolet (UV) radiation. Even higher-frequency waves are called X-rays, and higher still are gamma rays.

text: Visible light is an

text: electromagnetic wave

text: , consisting of oscillating

text: electric

text: and

text: magnetic field

text: s traveling through space. The frequency of the wave determines its color:  is red light,  is violet light, and between these (in the range 4-) are all the other colors of the

text: visible spectrum

text: . An electromagnetic wave can have a frequency less than , but it will be invisible to the human eye; such waves are called

text: infrared

text: (IR) radiation. At even lower frequency, the wave is called a

text: microwave

text: , and at still lower frequencies it is called a

text: radio wave

text: . Likewise, an electromagnetic wave can have a frequency higher than , but it will be invisible to the human eye; such waves are called

text: ultraviolet

text: (UV) radiation. Even higher-frequency waves are called

text: X-ray

text: s, and higher still are

text: gamma ray

text: s.

text: Blacklight sources may be specially designed fluorescent lamps, mercury vapor lamps, light-emitting diodes, lasers, or incandescent lamps; although incandescents produce almost no blacklight (except slightly more for halogen types), and so are not considered true blacklight sources.   In medicine, forensics, and some other scientific fields, such a light source is referred to as a Wood's lamp, named after Robert Williams Wood.

text: Blacklight sources may be specially designed

text: fluorescent lamp

text: s,

text: mercury vapor

text: lamps,

text: light-emitting diodes

text: lasers

text: , or

text: incandescent lamp

text: s; although incandescents produce almost no blacklight (except slightly more for halogen types), and so are not considered true blacklight sources.   In

text: medicine

text: forensics

text: , and some other scientific fields, such a light source is referred to as a Wood's lamp, named after

text: Robert Williams Wood

text: The downside of optical imaging is the lack of penetration depth, especially when working at visible wavelengths.  Depth of penetration is related to the absorption and scattering of light, which is primarily a function of the wavelength of the excitation source. Light is absorbed by endogenous chromophores found in living tissue (e.g. hemoglobin, melanin, and lipids). In general, light absorption and scattering decreases with increasing wavelength. Below ~700 nm (e.g. visible wavelengths), these effects result in shallow penetration depths of only a few millimeters. Thus, in the visible region of the spectrum, only superficial assessment of tissue features is possible. Above 900 nm, water absorption can interfere with signal-to-background ratio. Because the absorption coefficient of tissue is considerably lower in the near infrared (NIR) region (700-900 nm), light can penetrate more deeply, to depths of several centimeters.

text: The defects can be detected by different types of spectroscopy, including electron paramagnetic resonance (EPR), luminescence induced by light (photoluminescence, PL) or electron beam (cathodoluminescence, CL), and absorption of light in the infrared (IR), visible and UV parts of the spectrum. Absorption spectrum is used not only to identify the defects, but also to estimate their concentration; it can also distinguish natural from synthetic or enhanced diamonds.

text: The defects can be detected by different types of

text: spectroscopy

text: , including

text: electron paramagnetic resonance

text: (EPR),

text: luminescence

text: induced by light (

text: photoluminescence

text: , PL) or electron beam (

text: cathodoluminescence

text: , CL), and absorption of light in the

text: infrared

text: (IR), visible and UV parts of the spectrum.

text: Absorption spectrum

text: is used not only to identify the defects, but also to estimate their concentration; it can also distinguish natural from

text: synthetic

text: or

text: enhanced diamonds

text: The material works across a broad spectrum from near-infrared to visible light. Near-infrared is essential for telecommunications and optical communications, and visible light is important for sensors, microscopes and efficient solid-state light sources.

text: Microspectrophotometry is the measure of the spectra of microscopic samples using different wavelengths of electromagnetic radiation (e.g. ultraviolet, visible and near infrared, etc.) It is accomplished with microspectrophotometers, cytospectrophotometers, microfluorometers, Raman microspectrophotometers, etc. A microspectrophotometer can be configured to measure transmittance, absorbance, reflectance, light polarization, fluorescence or luminescence of sample areas less than a micrometer in diameter through a modified optical microscope.

text: Microspectrophotometry is the measure of the spectra of microscopic samples using different wavelengths of

text: electromagnetic radiation

text: (e.g.

text: ultraviolet

text: , visible and near

text: infrared

text: , etc.) It is accomplished with microspectrophotometers, cytospectrophotometers, microfluorometers, Raman microspectrophotometers, etc. A microspectrophotometer can be configured to measure

text: transmittance

text: absorbance

text: reflectance

text: light polarization

text: fluorescence

text: or

text: luminescence

text: of sample areas less than a micrometer in diameter through a modified optical microscope.

text: More efficient light sources, such as fluorescent lamps and LEDs, do not function by incandescence.

text: More efficient light sources, such as

text: fluorescent lamp

text: s and

text: LED

text: s, do not function by incandescence.

text: Many reticle illumination and pattern options are available. Common light sources used in firearm reflector sights include battery powered lights, fiber optic light collectors, and even tritium capsules. Some sights are specifically designed to be visible when viewed through night vision devices. The color of a sight reticle is often red or amber for visibility against most backgrounds. Some sights use a chevron or triangular pattern instead, to aid precision aiming and range estimation, and still others provide selectable patterns.

text: Many reticle illumination and pattern options are available. Common light sources used in firearm reflector sights include

text: battery

text: powered lights,

text: fiber optic

text: light collectors, and even

text: tritium

text: capsules. Some sights are specifically designed to be visible when viewed through

text: night vision device

text: s. The color of a sight reticle is often red or amber for visibility against most backgrounds. Some sights use a

text: chevron

text: or triangular pattern instead, to aid precision aiming and range estimation, and still others provide selectable patterns.

text: Gadolinium oxysulfide is a promising luminescent host material, because of its high density (7.32 g/cm) and high effective atomic number of Gd.  These characteristics lead to a high stopping power for X-ray radiation.  Several synthesis routes have been developed for processing GdOS phosphors, including: solid state reaction method, reduction method, combustion synthesis method, emulsion liquid membrane method, and gas sulfuration method.   The solid state reaction method and reduction methods are most commonly used because of their high reliability, low cost, and high luminescent properties. (Gd0.99, Pr0.01)2O2S sub-microphosphors synthesized by homogeneous precipitation method are very promising for a new green emitting material to be applied to the high resolution digital X-ray imaging field   Gadolinium oxysulfide powder phosphors are intensively used for conversion of X-rays to visible light in medical X-ray imaging.  GdOS: Pr based solid state X-ray detectors have been successfully reintroduced to X-ray sampling in medical computed tomography (imaging by sections or sectioning, through the use of any kind of penetrating wave).

text: Luminescence is the third international studio album by Anggun. The French-language version was released in France on 22 February 2005, while English-language version, also with the same title, was first released in Italy on 18 May 2005. The album was later repackaged in August 2006 as Luminescence: Special Edition with three brand new songs. Following her departure from Columbia Records in 2003, Anggun signed a recording contract with Heben Music. The album features production by several musicians, including Jean-Pierre Taïeb, Frédéric Jaffré and Niels Brinck. Anggun co-wrote music and lyrics of the entire album, except two tracks on the French version.

text: Luminescence is the third international

text: studio album

text: by

text: Anggun

text: . The

text: French-language

text: version was released in France on 22 February 2005, while

text: English-language

text: version, also with the same title, was first released in Italy on 18 May 2005. The album was later repackaged in August 2006 as Luminescence: Special Edition with three brand new songs. Following her departure from

text: Columbia Records

text: in 2003, Anggun signed a recording contract with Heben Music. The album features production by several musicians, including Jean-Pierre Taïeb, Frédéric Jaffré and

text: Niels Brinck

text: . Anggun co-wrote music and lyrics of the entire album, except two tracks on the French version.

text: The volume Bragg grating technology is also used to design tunable bandpass filters for various light sources. This technology combines an  out-of-band rejection of <-60 dB and an optical density higher than OD 6 with a tunability over the visible and near infrared regions of the electromagnetic spectrum.

text: The volume Bragg grating technology is also used to design tunable bandpass filters for various light sources. This technology combines an  out-of-band rejection of <-60 dB and an optical density higher than OD 6 with a tunability over the

text: visible

text: and

text: near infrared

text: regions of the

text: electromagnetic spectrum

text: CFLs radiate a spectral power distribution that is different from that of incandescent lamps. Improved phosphor formulations have improved the perceived color of the light emitted by CFLs, such that some sources rate the best "soft white" CFLs as subjectively similar in color to standard incandescent lamps.

text: CFLs radiate a

text: spectral power distribution

text: that is different from that of incandescent lamps. Improved

text: phosphor

text: formulations have improved the perceived color of the light emitted by CFLs, such that some sources rate the best "soft white" CFLs as subjectively similar in color to standard incandescent lamps.

text: For example, natural daylight has a color temperature of 6500 K and an illuminance of about 10 to 10 lux. This color temperature–illuminance pair results in natural color rendition, but if viewed at a low illuminance, would appear bluish. At typical indoor office illuminance levels of about 400 lux, pleasing color temperatures are lower (between 3000 and 6000 K), and at typical home illuminance levels of about 75 lux, pleasing color temperatures are even lower (between 2400 and 2700 K). These color temperature-illuminance pairs are often achieved with fluorescent and incandescent sources, respectively. It is noteworthy that the pleasing region of the curve contains color temperatures and illuminance levels comparable to naturally lit environments.

text: For example, natural daylight has a color temperature of 6500

text: K

text: and an illuminance of about 10 to 10

text: lux

text: . This color temperature–illuminance pair results in natural

text: color rendition

text: , but if viewed at a low illuminance, would appear bluish. At typical indoor office illuminance levels of about 400 lux, pleasing color temperatures are lower (between 3000 and 6000 K), and at typical home illuminance levels of about 75 lux, pleasing color temperatures are even lower (between 2400 and 2700 K). These color temperature-illuminance pairs are often achieved with

text: fluorescent

text: and

text: incandescent sources

text: , respectively. It is noteworthy that the pleasing region of the curve contains color temperatures and illuminance levels comparable to naturally lit environments.

text: A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves (unlike for example Cathode ray tube (CRT) displays), they need illumination (ambient light or a special light source) to produce a visible image. Backlights illuminate the LCD from the side or back of the display panel, unlike frontlights, which are placed in front of the LCD. Backlights are used in small displays to increase readability in low light conditions such as in wristwatches, and are used in smart phones, computer displays and LCD televisions to produce light in a manner similar to a CRT display. A review of some early backlighting schemes for LCDs is given in a report Engineering and Technology History by Peter J. Wild under its section Backlit LCDs.

text: A backlight is a form of illumination used in

text: liquid crystal display

text: s (LCDs). As LCDs do not produce light by themselves (unlike for example

text: Cathode ray tube

text: (CRT) displays), they need illumination (

text: ambient light

text: or a special light source) to produce a visible image. Backlights illuminate the LCD from the side or back of the display panel, unlike

text: frontlight

text: s, which are placed in front of the LCD. Backlights are used in small displays to increase readability in low light conditions such as in

text: wristwatches

text: , and are used in

text: smart phone

text: s,

text: computer display

text: s and

text: LCD television

text: s to produce light in a manner similar to a CRT display. A review of some early backlighting schemes for LCDs is given in a report Engineering and Technology History by Peter J. Wild under its section Backlit LCDs.

text: If the excitation source is periodic rather than pulsed, then the time response of the luminescence is correspondingly different. For instance, there is a phase difference between a sinusoidally varying light emitting diode (LED) signal of frequency f and the fluorescence that results (see figure). The phase difference varies with decay time and hence temperature as:

text: If the excitation source is periodic rather than pulsed, then the time response of the luminescence is correspondingly different. For instance, there is a phase difference between a sinusoidally varying

text: light emitting diode

text: (LED) signal of frequency f and the fluorescence that results (see figure). The phase difference varies with decay time and hence temperature as:

text: During the immediate post-war period, BEA suffered a number of accidents during approach and landing in poor visibility, which caused it to focus on the problems of how pilots could land safely in such conditions. A major breakthrough came with the recognition that in such low visibility the very limited visual information available (lights and so on) was extraordinarily easy to misinterpret, especially when the requirement to assess it was combined with a requirement to simultaneously fly the aircraft on instruments.  This led to the development of what is now widely understood as the "monitored approach" procedure whereby one pilot is assigned the task of accurate instrument flying while the other assesses the visual cues available at decision height, taking control to execute the landing once satisfied that the aircraft is in fact in the correct place and on a safe trajectory for a landing. The result was a major improvement in the safety of operations in low visibility, and as the concept clearly incorporates vast elements of what is now known as Crew Resource Management (although predating this phrase by some three decades) it was expanded to encompass a far broader spectrum of operations than just low visibility.

text: During the immediate post-war period, BEA suffered a number of accidents during approach and landing in poor visibility, which caused it to focus on the problems of how pilots could land safely in such conditions. A major breakthrough came with the recognition that in such low visibility the very limited visual information available (lights and so on) was extraordinarily easy to misinterpret, especially when the requirement to assess it was combined with a requirement to simultaneously fly the aircraft on instruments.  This led to the development of what is now widely understood as the "monitored approach" procedure whereby one pilot is assigned the task of accurate instrument flying while the other assesses the visual cues available at

text: decision height

text: , taking control to execute the landing once satisfied that the aircraft is in fact in the correct place and on a safe trajectory for a landing. The result was a major improvement in the safety of operations in low visibility, and as the concept clearly incorporates vast elements of what is now known as

text: Crew Resource Management

text: (although predating this phrase by some three decades) it was expanded to encompass a far broader spectrum of operations than just low visibility.

text: Some installations include medium- or high-intensity approach light systems (abbreviated ALS). Most often, these are at larger airports but many small general aviation airports in the U.S. have approach lights to support their ILS installations and obtain low-visibility minimums. The ALS assists the pilot in transitioning from instrument to visual flight, and to align the aircraft visually with the runway centerline. Pilot observation of the approach lighting system at the Decision Altitude allows the pilot to continue descending towards the runway, even if the runway or runway lights cannot be seen, since the ALS counts as runway end environment. In the U.S., an ILS without approach lights may have CAT I ILS visibility minimums as low as 3/4 mile (runway visual range of 4,000 feet) if the required obstacle clearance surfaces are clear of obstructions. Visibility minimums of 1/2 mile (runway visual range of 2,400 feet) are possible with a CAT I ILS approach supported by a  ALS, and 3/8 mile visibility  visual range is possible if the runway has high-intensity edge lights, touchdown zone and centerline lights, and an ALS that is at least  long (see Table 3-5a in FAA Order 8260.3b). In effect, ALS extends the runway environment out towards the landing aircraft and allows low-visibility operations. CAT II and III ILS approaches generally require complex high-intensity approach light systems, while medium-intensity systems are usually paired with CAT I ILS approaches. At many non-towered airports, the pilot controls the lighting system; for example, the pilot can key the microphone 7 times to turn on the lights on the high intensity, 5 times to medium intensity or 3 times for low intensity

text: Some installations include medium- or high-intensity

text: approach light systems

text: (abbreviated ALS). Most often, these are at larger airports but many small general aviation airports in the U.S. have approach lights to support their ILS installations and obtain low-visibility minimums. The ALS assists the pilot in transitioning from instrument to visual flight, and to align the aircraft visually with the runway centerline. Pilot observation of the approach lighting system at the Decision Altitude allows the pilot to continue descending towards the runway, even if the runway or runway lights cannot be seen, since the ALS counts as runway end environment. In the U.S., an ILS without approach lights may have CAT I ILS visibility minimums as low as 3/4 mile (runway visual range of 4,000 feet) if the required obstacle clearance surfaces are clear of obstructions. Visibility minimums of 1/2 mile (runway visual range of 2,400 feet) are possible with a CAT I ILS approach supported by a  ALS, and 3/8 mile visibility

text: visual range

text: is possible if the runway has high-intensity edge lights, touchdown zone and centerline lights, and an ALS that is at least  long (see Table 3-5a in FAA Order 8260.3b). In effect, ALS extends the runway environment out towards the landing aircraft and allows low-visibility operations. CAT II and III ILS approaches generally require complex high-intensity approach light systems, while medium-intensity systems are usually paired with CAT I ILS approaches. At many

text: non-towered airport

text: s, the

text: pilot controls the lighting system

text: ; for example, the pilot can key the microphone 7 times to turn on the lights on the high intensity, 5 times to medium intensity or 3 times for low intensity

text: Illumination works by arranging "building blocks" in order to visually describe the functionality of a software application. Like many other Visual programming languages, Illumination does not require any code to be written by hand in order to develop software.

text: Illumination works by arranging "building blocks" in order to visually describe the functionality of a software application. Like many other

text: Visual programming language

text: s, Illumination does not require any code to be written by hand in order to develop software.

text: Incandescence is exploited in incandescent light bulbs, in which a filament is heated to a temperature at which a fraction of the radiation falls in the visible spectrum. The majority of the radiation however, is emitted in the infrared part of the spectrum, rendering incandescent lights relatively inefficient as a light source. If the filament could be made hotter, efficiency would increase; however, there are currently no materials able to withstand such temperatures which would be appropriate for use in lamps.

text: Incandescence is exploited in

text: incandescent light bulb

text: s, in which a filament is heated to a temperature at which a fraction of the radiation falls in the visible spectrum. The majority of the radiation however, is emitted in the infrared part of the spectrum, rendering incandescent lights relatively inefficient as a light source. If the filament could be made hotter, efficiency would increase; however, there are currently no materials able to withstand such temperatures which would be appropriate for use in lamps.

text: The cineplex was altered in 2000 when the Edwards Cinemas was bought by Regal Entertainment Group. Entrances to theatres were relocated to less-visible locations and were converted to stadium seating which eliminated up to a third of their seating capacity. The theatre was highly visible at night, bearing over two miles of pink and purple neon lights. This night-time visibility has since been reduced by the addition of parking structures and the centre's second phase.

text: The cineplex was altered in 2000 when the Edwards Cinemas was bought by

text: Regal Entertainment Group

text: . Entrances to theatres were relocated to less-visible locations and were converted to stadium seating which eliminated up to a third of their seating capacity. The theatre was highly visible at night, bearing over two miles of pink and purple neon lights. This night-time visibility has since been reduced by the addition of parking structures and the centre's second phase.

text: Various sources define visible light as narrowly as 420 to 680 to as broadly as 380 to 800 nm. Under ideal laboratory conditions, people can see infrared up to at least 1050 nm; children and young adults may perceive ultraviolet wavelengths down to about 310 to 313 nm.

text: In 1939 he demonstrated that the major source of optical opacity in the Sun's atmosphere is the H ion, and thus the main source of visible light for the Sun and stars.

text: In 1939 he demonstrated that the major source of optical opacity in the Sun's atmosphere is the

text: H

text: ion, and thus the main source of visible light for the Sun and stars.

text: Illuminants B and C are daylight simulators. They are derived from Illuminant A by using liquid filters. B served as a representative of noon sunlight, with a correlated color temperature (CCT) of 4874 K, while C represented average day light with a CCT of 6774 K. They are poor approximations of any phase of natural daylight, particularly in the short-wave visible and in the ultraviolet spectral ranges. Still, the lighting cabinets, such as the Spectralight III, that use filtered incandescent lamps have better fits to the D illuminants in the  to  range than do the fluorescent daylight simulators. As a result, these illuminants have been deprecated in favor of the D series:

text: Illuminants B and C are daylight simulators. They are derived from Illuminant A by using liquid filters. B served as a representative of noon sunlight, with a

text: correlated color temperature

text: (CCT) of 4874 K, while C represented average day light with a CCT of 6774 K. They are poor approximations of any phase of natural daylight, particularly in the short-wave visible and in the ultraviolet spectral ranges. Still, the lighting cabinets, such as the Spectralight III, that use filtered incandescent lamps have better fits to the D illuminants in the  to  range than do the fluorescent daylight simulators. As a result, these illuminants have been deprecated in favor of the D series:

text: The shortened barrel of a Source Four PAR (relative to a traditional PAR fixture) makes the light source more visible at a much greater angle.  In some cases, this may be considered an unwelcome effect as it can cause lens flare or change the audience's perception of a theatrical scene. top hats or barn doors attach to Source Four PARs to eliminate this source visibility.

text: The shortened barrel of a Source Four PAR (relative to a traditional PAR fixture) makes the light source more visible at a much greater angle.  In some cases, this may be considered an unwelcome effect as it can cause lens flare or change the audience's perception of a theatrical scene.

text: top hats

text: or

text: barn doors

text: attach to Source Four PARs to eliminate this source visibility.

text: Shadows are created by testing whether a pixel is visible from the light source, by comparing the pixel to a z-buffer or depth image of the light source's view, stored in the form of a texture.

text: Shadows are created by testing whether a

text: pixel

text: is visible from the light source, by comparing the pixel to a

text: z-buffer

text: or depth image of the light source's view, stored in the form of a

text: texture

text: Luminescence dating methods are not radiometric dating methods in that they do not rely on abundances of isotopes to calculate age. Instead, they are a consequence of background radiation on certain minerals. Over time, ionizing radiation is absorbed by mineral grains in sediments and archaeological materials such as quartz and potassium feldspar. The radiation causes charge to remain within the grains in structurally unstable "electron traps". Exposure to sunlight or heat releases these charges, effectively "bleaching" the sample and resetting the clock to zero. The trapped charge accumulates over time at a rate determined by the amount of background radiation at the location where the sample was buried. Stimulating these mineral grains using either light (optically stimulated luminescence or infrared stimulated luminescence dating) or heat (thermoluminescence dating) causes a luminescence signal to be emitted as the stored unstable electron energy is released, the intensity of which varies depending on the amount of radiation absorbed during burial and specific properties of the mineral.

text: Luminescence dating methods are not radiometric dating methods in that they do not rely on abundances of isotopes to calculate age. Instead, they are a consequence of

text: background radiation

text: on certain minerals. Over time,

text: ionizing radiation

text: is absorbed by mineral grains in sediments and archaeological materials such as

text: quartz

text: and

text: potassium feldspar

text: . The radiation causes charge to remain within the grains in structurally unstable "electron traps". Exposure to sunlight or heat releases these charges, effectively "bleaching" the sample and resetting the clock to zero. The trapped charge accumulates over time at a rate determined by the amount of background radiation at the location where the sample was buried. Stimulating these mineral grains using either light (

text: optically stimulated luminescence

text: or infrared stimulated luminescence dating) or heat (

text: thermoluminescence dating

text: ) causes a luminescence signal to be emitted as the stored unstable electron energy is released, the intensity of which varies depending on the amount of radiation absorbed during burial and specific properties of the mineral.

text: A further internal diagonal passes through the space occupied by the Infanta. There is a similar connection between the female dwarf and the figure of Velázquez himself, both of whom look towards the viewer from similar angles, creating a visual tension. The face of Velázquez is dimly lit by light that is reflected, rather than direct. For this reason his features, though not as sharply defined, are more visible than those of the dwarf who is much nearer the light source. This appearance of a total face, full-on to the viewer, draws the attention, and its importance is marked, tonally, by the contrasting frame of dark hair, the light on the hand and brush, and the skilfully placed triangle of light on the artist's sleeve, pointing directly to the face.

text: One key technique for achieving high sensitivity in the FUV is minimizing the number of optics. This is done because FUV reflection and transmission efficiencies are typically quite low compared to what is common at visible wavelengths. In accomplishing this, the COS FUV channel uses a single (selectable) optic to diffract the light from HST, correct for the Hubble spherical aberration, focus the diffracted light onto the FUV detector and correct for astigmatism typical of this sort of instrument. Since aberration correction is performed after the light passes into the instrument, the entrance to the spectrograph must be an extended aperture, rather than the traditional narrow entrance slit, in order to allow the entire aberrated HST image from a point source to enter the instrument. The 2.5 arc second diameter entrance aperture allows ≈ 95% of the light from compact sources to enter COS, yielding high sensitivity at the design resolution for compact sources.

text: One key technique for achieving high sensitivity in the FUV is minimizing the number of optics. This is done because FUV reflection and transmission efficiencies are typically quite low compared to what is common at visible wavelengths. In accomplishing this, the COS FUV channel uses a single (selectable) optic to diffract the light from HST, correct for the

text: Hubble spherical aberration

text: , focus the diffracted light onto the FUV detector and correct for astigmatism typical of this sort of instrument. Since aberration correction is performed after the light passes into the instrument, the entrance to the spectrograph must be an extended aperture, rather than the traditional narrow entrance slit, in order to allow the entire aberrated HST image from a point source to enter the instrument. The 2.5 arc second diameter entrance aperture allows ≈ 95% of the light from compact sources to enter COS, yielding high sensitivity at the design resolution for compact sources.

text: Although inefficient, incandescent light bulbs have an advantage in applications where accurate color reproduction is important, since the continuous blackbody spectrum emitted from an incandescent light-bulb filament yields near-perfect color rendition, with a color rendering index of 100 (the best possible). White-balancing is still required to avoid too "warm" or "cool" colors, but this is a simple process that requires only the color temperature in Kelvin as input for modern, digital visual reproduction equipment such as video or still cameras unless it is completely automated. The color-rendering performance of incandescent lights cannot be matched by LEDs or fluorescent lights, although they can offer satisfactory performance for non-critical applications such as home lighting. White-balancing such lights is therefore more complicated, requiring additional adjustments to reduce for example green-magenta color casts, and even when properly white-balanced, the color reproduction will not be perfect.

text: Although inefficient, incandescent light bulbs have an advantage in applications where accurate color reproduction is important, since the continuous blackbody spectrum emitted from an incandescent light-bulb filament yields near-perfect color rendition, with a

text: color rendering index

text: of 100 (the best possible). White-balancing is still required to avoid too "warm" or "cool" colors, but this is a simple process that requires only the color temperature in Kelvin as input for modern, digital visual reproduction equipment such as video or still cameras unless it is completely automated. The color-rendering performance of incandescent lights cannot be matched by LEDs or fluorescent lights, although they can offer satisfactory performance for non-critical applications such as home lighting. White-balancing such lights is therefore more complicated, requiring additional adjustments to reduce for example green-magenta color casts, and even when properly white-balanced, the color reproduction will not be perfect.

text: Skyglow is the illumination of the night sky or parts of it, resembling an orange "smog". It occurs from both natural and human-made sources. Artificial skyglow is caused by the over-illumination of the sky from large city centres, shopping centres, or stadiums. It consists of light that is either emitted directly upward or reflected from the ground that is then scattered by dust and gas molecules in the atmosphere, producing a luminous background or light dome. These artificial skyglows cause the sky to be 5–10 times brighter in urban areas than a naturally dark sky that is unaffected by artificial light. Natural skyglow can come from natural light sources, such as the Sun, the Moon, the stars, or auroras.

text: Skyglow

text: is the illumination of the

text: night sky

text: or parts of it, resembling an orange "

text: smog

text: ". It occurs from both natural and human-made sources. Artificial skyglow is caused by the

text: over-illumination

text: of the sky from large city centres, shopping centres, or stadiums. It consists of light that is either emitted directly upward or reflected from the ground that is then scattered by dust and gas molecules in the atmosphere, producing a luminous background or light dome. These artificial skyglows cause the sky to be 5–10 times brighter in urban areas than a naturally dark sky that is unaffected by artificial light. Natural skyglow can come from

text: natural light

text: sources, such as the

text: Sun

text: , the

text: Moon

text: , the

text: stars

text: , or

text: aurora

text: s.

text: The luminescent features of the stamps are generally invisible or barely visible to the human eye in normal illumination. They can, however, be identified under ultraviolet light similar to the way it is done in the postal machinery. In general, fluorescent features can be identified with UV light of a longer wavelength than needed for phosphorescent features (see below).

text: For the simplified scenario of visible light travelling from air (n ≈ 1.0) into common glass (), value of R is 0.04, or 4%, on a single reflection. So at most 96% of the light ( 1 − R  0.96}}) actually enters the glass, and the rest is reflected from the surface. The amount of light reflected is known as the reflection loss.

text: Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to normal levels of background radiation. The term irradiation usually excludes the exposure to non-ionizing radiation, such as infrared, visible light, microwaves from cellular phones or electromagnetic waves emitted by radio and TV receivers and power supplies.

text: Irradiation is the process by which an object is exposed to

text: radiation

text: . The exposure can originate from various sources, including natural sources. Most frequently the term refers to

text: ionizing radiation

text: , and to a level of radiation that will serve a specific purpose, rather than radiation

text: exposure

text: to normal levels of

text: background radiation

text: . The term irradiation usually excludes the exposure to non-ionizing radiation, such as

text: infrared

text: visible light

text: microwave

text: s from

text: cellular phone

text: s or

text: electromagnetic wave

text: s emitted by radio and TV receivers and power supplies.

text: Materials which do not transmit light are called opaque. Many such substances have a chemical composition which includes what are referred to as absorption centers. Many substances are selective in their absorption of white light frequencies. They absorb certain portions of the visible spectrum while reflecting others. The frequencies of the spectrum which are not absorbed are either reflected or transmitted for our physical observation. This is what gives rise to color. The attenuation of light of all frequencies and wavelengths is due to the combined mechanisms of absorption and scattering.

text: Materials which do not

text: transmit

text: light are called

text: opaque

text: . Many such substances have a

text: chemical composition

text: which includes what are referred to as

text: absorption

text: centers. Many substances are selective in their absorption of

text: white light

text: frequencies

text: . They absorb certain portions of the

text: visible spectrum

text: while reflecting others. The frequencies of the spectrum which are not absorbed are either reflected or transmitted for our physical observation. This is what gives rise to

text: color

text: . The attenuation of light of all frequencies and wavelengths is due to the combined mechanisms of absorption and

text: scattering

text: Around the turn of the century arc-lighting systems were in decline, but Thomson-Houston controlled key patents to urban lighting systems. This control slowed the expansion of incandescent lighting systems being developed by Thomas Edison's Edison General Electric Company. Conversely, Edison's control of direct current distribution and generating machinery patents blocked further expansion of Thomson-Houston. The roadblock to expansion was removed when the two companies merged in 1892 to form the General Electric Company.

text: Around the turn of the century arc-lighting systems were in decline, but Thomson-Houston controlled key patents to urban lighting systems. This control slowed the expansion of incandescent lighting systems being developed by

text: Thomas Edison

text: 's

text: Edison General Electric Company

text: . Conversely, Edison's control of direct current distribution and generating machinery patents blocked further expansion of Thomson-Houston. The roadblock to expansion was removed when the two companies merged in 1892 to form the

text: General Electric Company

text: The Source Four is the first ERS to use a faceted borosilicate reflector behind the lamp.  Nearly all stage lights have some form of reflector positioned behind the lamp to reflect otherwise wasted light out of the front of the instrument.  The Source Four's reflector is dichroic, meaning that it reflects light of only certain wavelengths.  The Source Four's reflector reflects back 95% of the visible light striking it, while allowing over 90% of the infrared radiation (heat) to pass out the back of the instrument. This produces a much cooler light which is less destructive to gobos or color gels at the front of the fixture, and reduces localized heating of the lighting target.

text: The Source Four is the first ERS to use a faceted

text: borosilicate

text: reflector behind the lamp.  Nearly all

text: stage lights

text: have some form of reflector positioned behind the lamp to reflect otherwise wasted light out of the front of the instrument.  The Source Four's reflector is

text: dichroic

text: , meaning that it reflects

text: light

text: of only certain wavelengths.  The Source Four's reflector reflects back 95% of the visible light striking it, while allowing over 90% of the

text: infrared

text: radiation (heat) to pass out the back of the instrument. This produces a much cooler light which is less destructive to

text: gobo

text: s or

text: color gel

text: s at the front of the fixture, and reduces localized heating of the lighting target.

text: Some authors, as in this article, use the term chromosome in a wider sense, to refer to the individualized portions of chromatin in cells, either visible or not under light microscopy. However, others use the concept in a narrower sense, to refer to the individualized portions of chromatin during cell division, visible under light microscopy due to high condensation.

text: The intensity (or illuminance or irradiance) of light or other linear waves radiating from a point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only one-quarter the energy (in the same time period).

text: The

text: intensity

text: (or

text: illuminance

text: or

text: irradiance

text: ) of

text: light

text: or other linear waves radiating from a

text: point source

text: (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only one-quarter the

text: energy

text: (in the same time period).

text: The illuminance provided by a light source, on a surface perpendicular to the direction to the source, is a measure of the strength of that source as perceived from that location. For instance, a star of apparent magnitude 0 provides 2.08 microlux at the earth's surface. A barely perceptible magnitude 6 star provides 8 nanolux. The unobscured sun provides an illumination of up to 100 kilolux on the Earth's surface, the exact value depending on time of year and atmospheric conditions. This direct normal illuminance is related to the solar illuminance constant E, equal to  (see Sunlight).

text: The illuminance provided by a light source, on a surface perpendicular to the direction to the source, is a measure of the strength of that source as perceived from that location. For instance, a star of

text: apparent magnitude

text: 0 provides 2.08 microlux at the earth's surface. A barely perceptible magnitude 6 star provides 8 nanolux. The unobscured sun provides an illumination of up to 100 kilolux on the Earth's surface, the exact value depending on time of year and atmospheric conditions. This direct normal illuminance is related to the

text: solar illuminance constant

text: E, equal to  (see

text: Sunlight

text: Although many other types of lamp emit ultraviolet light with visible light, black lights are essential when UV-A light without visible light is needed, particularly in observing fluorescence, the colored glow that many substances emit when exposed to UV.  Black lights are employed for decorative and artistic lighting effects, diagnostic and therapeutic uses in medicine, the detection of substances tagged with fluorescent dyes, rock-hunting, the detection of counterfeit money, the curing of plastic resins, and attracting insects.  Strong sources of long-wave ultraviolet light are used in tanning beds.  Although the low-power UV-A emitted by black lights is not a hazard to skin or eyes and can be viewed without protection, powerful ultraviolet sources present dangers and require personal protective equipment such as goggles and gloves.

text: Although many other types of lamp emit ultraviolet light with visible light, black lights are essential when UV-A light without visible light is needed, particularly in observing

text: fluorescence

text: , the colored glow that many substances emit when exposed to UV.  Black lights are employed for decorative and artistic lighting effects, diagnostic and therapeutic uses in medicine, the detection of substances tagged with

text: fluorescent dye

text: s,

text: rock-hunting

text: , the detection of

text: counterfeit money

text: , the curing of plastic resins, and attracting insects.  Strong sources of long-wave ultraviolet light are used in

text: tanning bed

text: s.  Although the low-power UV-A emitted by black lights is not a hazard to skin or eyes and can be viewed without protection, powerful ultraviolet sources present dangers and require

text: personal protective equipment

text: such as goggles and gloves.

text: The alexandrite variety displays a color change (alexandrite effect) dependent upon the nature of ambient lighting. Alexandrite effect is the phenomenon of an observed color change from greenish to reddish with a change in source illumination.  Alexandrite results from small scale replacement of aluminium by chromium ions in the crystal structure, which causes intense absorption of light over a narrow range of wavelengths in the yellow region (580 nm) of the visible light spectrum.  Because human vision is more sensitive to light in the green spectrum and the red spectrum, alexandrite appears greenish in daylight where a full spectrum of visible light is present and reddish in incandescent light which emits less green and blue spectrum.  This color change is independent of any change of hue with viewing direction through the crystal that would arise from pleochroism.

text: The alexandrite variety displays a color change (alexandrite effect) dependent upon the nature of ambient lighting. Alexandrite effect is the phenomenon of an observed color change from greenish to reddish with a change in source illumination.  Alexandrite results from small scale replacement of aluminium by chromium ions in the crystal structure, which causes intense absorption of light over a narrow range of wavelengths in the yellow region (580

text: nm

text: ) of the visible light spectrum.  Because human vision is more sensitive to light in the green spectrum and the red spectrum, alexandrite appears greenish in daylight where a full spectrum of visible light is present and reddish in incandescent light which emits less green and blue spectrum.  This color change is independent of any change of hue with viewing direction through the crystal that would arise from

text: pleochroism

text: Electronics 7 is a Soviet Russian brand of seven-segment industrial digital clocks with four or eleven seven-segment luminescent digits.  It had a separate binary-to-seven-segment decoder board for each digit, while the actual timekeeping was done by a main board which emitted the digits of the time as binary code.  Most models used Russian-made vacuum-fluorescent indicators, but there were also models based on light-emitting diodes. The most common problem with the clocks was that the segments of the display were gradually burnt out after ten or more years of continuous use, causing a significant difference in luminescence between more often and less often displayed segments.  All the street and wall clocks were based on a kit by the "Reflector" factory in Saratov, and many remain in use at administrative and industrial premises in Russia.

text: Electronics 7 is a

entity_name: Russian Soviet Federative Socialist Republic

text: Soviet Russian

text: brand of

text: seven-segment

text: industrial

text: digital clock

text: s with four or eleven seven-segment

text: luminescent

text: digits.  It had a separate binary-to-seven-segment decoder board for each digit, while the actual timekeeping was done by a main board which emitted the digits of the time as

text: binary code

text: .  Most models used Russian-made

text: vacuum-fluorescent indicators

text: , but there were also models based on

text: light-emitting diode

text: s. The most common problem with the clocks was that the segments of the display were gradually burnt out after ten or more years of continuous use, causing a significant difference in luminescence between more often and less often displayed segments.  All the street and wall clocks were based on a kit by the "Reflector" factory in

text: Saratov

text: , and many remain in use at administrative and industrial premises in

text: Russia

text: Photostimulated luminescence (PSL) is the release of stored energy within a phosphor by stimulation with visible light, to produce a luminescent signal. Commonly this is used to allow the storage of a weak radioactive signal in a phosphor plate that takes the place of X-ray film, potentially over a prolonged period, which PSL transforms to obtain a highly sensitive image of the original pattern of radiation. Also known as an image plate, a photostimulable phosphor (PSP) plate can be used to record a two-dimensional image of the intensity short-wavelength (typically, X-ray) electromagnetic radiation. The device to read such a plate is known as a phosphorimager (occasionally spelled phosphoimager, perhaps reflecting its common application in molecular biology for detecting radiolabeled phosphorylated proteins and nucleic acids).

text: Photostimulated luminescence (PSL) is the release of stored energy within a

text: phosphor

text: by stimulation with visible light, to produce a luminescent signal. Commonly this is used to allow the storage of a weak radioactive signal in a phosphor plate that takes the place of X-ray film, potentially over a prolonged period, which PSL transforms to obtain a highly sensitive image of the original pattern of radiation. Also known as an image plate, a photostimulable phosphor (PSP) plate can be used to record a

text: two-dimensional

text: image

text: of the intensity short-

text: wavelength

text: (typically,

text: X-ray

text: electromagnetic radiation

text: . The device to read such a plate is known as a phosphorimager (occasionally spelled phosphoimager, perhaps reflecting its common application in

text: molecular biology

text: for detecting

text: radiolabel

text: ed

text: phosphorylated

text: proteins

text: and

text: nucleic acids

text: Also visible is the Light Ship Carpentaria.

text: Also visible is the

text: Light Ship

text: Carpentaria.

text: , vanish and the system becomes quasistationary, semiconductors emit incoherent light spontaneously, commonly referred to as luminescence (L). The corresponding luminescence flux is proportional to the temporal change in photon number,

text: , vanish and the system becomes quasistationary, semiconductors emit

text: incoherent

text: light spontaneously, commonly referred to as

text: luminescence

text: (L). The corresponding luminescence

text: flux

text: is proportional to the temporal change in photon number,

text: Illuminants are unique location to location across the globe, however several types of illuminant have been standardized by the CIE. Illuminants types D65 and D50 are acceptable for use, however D50 illuminant is suggested for a calibrated and accurate color vision test result. Use of different illuminant can sway results in a significant manner due to the spectral power distribution of alternate sources and their incident effect on how displayed information is processed by the human visual system. Illuminants containing varying concentrations of differing wavelength intensity light skews the representation of color on the screen in a manner that would cause the eye to mismatch color patches. In combination with the spatial acuity function of the human visual system, illumination plays a significant role in the color accuracy of a display.

text: Illuminants

text: are unique location to location across the globe, however several types of illuminant have been standardized by the

entity_name: International Commission on Illumination

text: CIE

text: . Illuminants types

text: and

text: are acceptable for use, however

text: D50 illuminant

text: is suggested for a

text: calibrated

text: and accurate color vision test result. Use of different illuminant can sway results in a significant manner due to the

text: spectral power distribution

text: of alternate sources and their

text: incident

text: effect on how displayed information is processed by the human visual system. Illuminants containing varying concentrations of differing

text: wavelength

text: intensity

text: light skews the

text: representation of color on the screen

text: in a manner that would cause the eye to mismatch color patches. In combination with the

text: spatial acuity function

text: of the human visual system,

text: illumination

text: plays a significant role in the

text: color accuracy of a display

text: A panel of a plasma display typically comprises millions of tiny compartments in between two panels of glass. These compartments, or "bulbs" or "cells", hold a mixture of noble gases and a minuscule amount of another gas (e.g., mercury vapor). Just as in the fluorescent lamps over an office desk, when a high voltage is applied across the cell, the gas in the cells forms a plasma. With flow of electricity (electrons), some of the electrons strike mercury particles as the electrons move through the plasma, momentarily increasing the energy level of the atom until the excess energy is shed. Mercury sheds the energy as ultraviolet (UV) photons. The UV photons then strike phosphor that is painted on the inside of the cell. When the UV photon strikes a phosphor molecule, it momentarily raises the energy level of an outer orbit electron in the phosphor molecule, moving the electron from a stable to an unstable state; the electron then sheds the excess energy as a photon at a lower energy level than UV light; the lower energy photons are mostly in the infrared range but about 40% are in the visible light range. Thus the input energy is converted to mostly infrared but also as visible light. The screen heats up to between  during operation. Depending on the phosphors used, different colors of visible light can be achieved. Each pixel in a plasma display is made up of three cells comprising the primary colors of visible light. Varying the voltage of the signals to the cells thus allows different perceived colors.

text: A panel of a plasma display typically comprises millions of tiny compartments in between two panels of glass. These compartments, or "bulbs" or "cells", hold a mixture of

text: noble gases

text: and a minuscule amount of another gas (e.g., mercury vapor). Just as in the fluorescent lamps over an office desk, when a high voltage is applied across the cell, the gas in the cells forms a

text: plasma

text: . With flow of electricity (

text: electron

text: s), some of the electrons strike mercury particles as the electrons move through the plasma, momentarily increasing the energy level of the atom until the excess energy is shed. Mercury sheds the energy as ultraviolet (UV) photons. The UV photons then strike phosphor that is painted on the inside of the cell. When the UV photon strikes a phosphor molecule, it momentarily raises the energy level of an outer orbit electron in the phosphor molecule, moving the electron from a stable to an unstable state; the electron then sheds the excess energy as a photon at a lower energy level than UV light; the lower energy photons are mostly in the infrared range but about 40% are in the visible light range. Thus the input energy is converted to mostly infrared but also as visible light. The screen heats up to between  during operation. Depending on the phosphors used, different colors of visible light can be achieved. Each pixel in a plasma display is made up of three cells comprising the primary colors of visible light. Varying the voltage of the signals to the cells thus allows different perceived colors.

text: The inspector will use visible light with adequate intensity (100 foot-candles or 1100 lux is typical) for visible dye penetrant. Ultraviolet (UV-A) radiation of adequate intensity (1,000 micro-watts per centimeter squared is common), along with low ambient light levels (less than 2 foot-candles) for fluorescent penetrant examinations.  Inspection of the test surface should take place after 10- to 30-minute development time, depends of product kind.  This time delay allows the blotting action to occur.  The inspector may observe the sample for indication formation when using visible dye.  It is also good practice to observe indications as they form because the characteristics of the bleed out are a significant part of interpretation characterization of flaws.

text: The inspector will use visible light with adequate intensity (100

text: foot-candles

text: or 1100

text: lux

text: is typical) for visible dye penetrant. Ultraviolet (UV-A) radiation of adequate intensity (1,000 micro-watts per centimeter squared is common), along with low ambient light levels (less than 2 foot-candles) for fluorescent penetrant examinations.  Inspection of the test surface should take place after 10- to 30-minute development time, depends of product kind.  This time delay allows the blotting action to occur.  The inspector may observe the sample for indication formation when using visible dye.  It is also good practice to observe indications as they form because the characteristics of the bleed out are a significant part of interpretation characterization of flaws.

text: Engadget has described the game as "a mix of Minecraft-esque collaborative building, social economics and a Soviet Union-themed post-apocalyptic dystopia." The Tomorrow Children runs on a proprietary game engine developed by Q-Games. The game's graphics engine utilizes new technology, aiming to achieve a Pixar-like pre-rendered CGI look with real-time 3D graphics. It utilizes the PlayStation 4's Async Compute technology extensively. It features new lighting techniques developed by Q-Games, such as cascaded voxel cone ray tracing, which simulates lighting in real-time and uses more realistic reflections rather than screen space reflections. This allows real-time global illumination, without any need for pre-calculated or pre-baked lighting. It supports direct and indirect illumination in real-time, and up to three bounces of light per pixel from all directions (compared to one bounce for Pixar films). It also features deformable landscapes, with layered depth cubes, representing the world as volumes, which are then converted to polygons as needed.

text: Engadget has described the game as "a mix of

text: Minecraft

text: -esque collaborative building, social economics and a Soviet Union-themed post-apocalyptic dystopia." The Tomorrow Children runs on a proprietary

text: game engine

text: developed by Q-Games. The game's

text: graphics engine

text: utilizes new technology, aiming to achieve a

text: Pixar

text: -like

text: pre-rendered

text: CGI

text: look with

text: real-time

text: 3D graphics

text: . It utilizes the

text: PlayStation 4

text: 's

text: Async Compute

text: technology extensively. It features new

text: lighting

text: techniques developed by Q-Games, such as cascaded

text: voxel

text: cone

text: ray tracing

text: , which simulates lighting in real-time and uses more realistic

text: reflections

text: rather than

text: screen space

text: reflections. This allows real-time

text: global illumination

text: , without any need for

text: pre-calculated

text: or

text: pre-baked lighting

text: . It supports direct and

text: indirect illumination

text: in real-time, and up to three

text: bounces of light

text: per pixel

text: from all directions (compared to one bounce for Pixar films). It also features

text: deformable

text: landscapes, with layered depth cubes, representing the

text: world

text: as

text: volumes

text: , which are then converted to

text: polygons

text: as needed.

text: A standard illuminant is a theoretical source of visible light with a profile (its spectral power distribution) which is published. Standard illuminants provide a basis for comparing images or colors recorded under different lighting.

text: A standard illuminant is a theoretical source of

text: visible light

text: with a profile (its

text: spectral power distribution

text: ) which is published. Standard illuminants provide a basis for comparing images or colors recorded under different lighting.

text: Wavelengths of light outside of the visible spectrum are not useful for illumination because they cannot be seen by the human eye. Furthermore, the eye responds more to some wavelengths of light than others, even within the visible spectrum. This response of the eye is represented by the luminosity function. This is a standardized function which represents the response of a "typical" eye under bright conditions (photopic vision). One can also define a similar curve for dim conditions (scotopic vision). When neither is specified, photopic conditions are generally assumed.

text: Wavelength

text: s of light outside of the

text: visible spectrum

text: are not useful for illumination because they cannot be seen by the

text: human eye

text: . Furthermore, the eye responds more to some wavelengths of light than others, even within the visible spectrum. This response of the eye is represented by the

text: luminosity function

text: . This is a standardized function which represents the response of a "typical" eye under bright conditions (

text: photopic vision

text: ). One can also define a similar curve for dim conditions (

text: scotopic vision

text: ). When neither is specified, photopic conditions are generally assumed.

text: The New York Times review was generally positive, but: "About that styling: I love it, but you might hate it. ... The face is dominated by bug-eye headlamps, and the running lights bulge up above the hood such that they’re in the driver’s line of sight. At night, the effect is of large bio-luminescent slugs lounging atop the front fenders. Admittedly, it’s more appealing than I’m making it sound."

text: Morecambe's Illuminations once highlighted the promenade with a "spectacular wonderland of light" in the resort's main park - Happy Mount Park. The lights ran from 1919 until 1996, famous faces such as Roger Moore and Noel Edmonds and even the towns most famous son and his companion, Morecambe and Wise were called upon to switch the Illuminations on for each season. In 2015, Callum Henry, set up an ambitious campaign of proposals in which to bring back the illuminations. By 2016 a community Mini-Illuminations project funded by the Big Local National Lottery fund, and hosted by the West Street Exchange and @ShrimpingIt led to the first new Morecambe illuminations for twenty years, with 31 new tableaux designed by members of the Morecambe community and installed for the first time in Alexandra Square on November 30th 2016.

text: Morecambe's Illuminations once highlighted the promenade with a "spectacular wonderland of light" in the resort's main park - Happy Mount Park. The lights ran from 1919 until 1996, famous faces such as

text: Roger Moore

text: and

text: Noel Edmonds

text: and even the towns most famous son and his companion,

text: Morecambe and Wise

text: were called upon to switch the Illuminations on for each season. In 2015, Callum Henry, set up an ambitious campaign of proposals in which to bring back the illuminations. By 2016 a community Mini-Illuminations project funded by the Big Local National Lottery fund, and hosted by the West Street Exchange and @ShrimpingIt led to the first new Morecambe illuminations for twenty years, with 31 new tableaux designed by members of the Morecambe community and installed for the first time in Alexandra Square on November 30th 2016.

text: P. rubra exhibits bioluminescence, light produced by a chemical reaction within a living organism. Bio-luminescence is a type of luminescence, which is the term for a light-producing chemical reaction. Bio-luminescence is a "cold light" in that less than 20% of the light generates heat.

text: P. rubra exhibits

text: bioluminescence

text: , light produced by a chemical reaction within a living organism. Bio-luminescence is a type of

text: luminescence

text: , which is the term for a light-producing chemical reaction. Bio-luminescence is a "cold light" in that less than 20% of the light generates heat.

text: Specification of illumination requirements is the basic concept of deciding how much illumination is required for a given task. Clearly, much less light is required to illuminate a hallway compared to that needed for a word processing work station.  Generally speaking, the energy expended is proportional to the design illumination level. For example, a lighting level of 400 lux might be chosen for a work environment involving meeting rooms and conferences, whereas a level of 80 lux could be selected for building hallways. If the hallway standard simply emulates the conference room needs, then much more energy will be consumed than is needed. Unfortunately, most of the lighting standards even today have been specified by industrial groups who manufacture and sell lighting, so that a historical commercial bias exists in designing most building lighting, especially for office and industrial settings.

text: Specification of illumination requirements is the basic concept of deciding how much illumination is required for a given task. Clearly, much less light is required to illuminate a hallway compared to that needed for a

text: word processing

text: work station.  Generally speaking, the

text: energy

text: expended is proportional to the design illumination level. For example, a lighting level of 400

text: lux

text: might be chosen for a work environment involving meeting rooms and conferences, whereas a level of 80 lux could be selected for building hallways. If the hallway standard simply emulates the conference room needs, then much more energy will be consumed than is needed. Unfortunately, most of the lighting standards even today have been specified by industrial groups who manufacture and sell lighting, so that a historical commercial bias exists in designing most building lighting, especially for office and industrial settings.

text: Oblique illumination dispersion staining is the result of refraction and the convex shape of most particles.  With oblique illumination the beam of light illuminating the sample is directed at an oblique angle through the sample.  This enhances the resolution of structural details in the particle that are oriented at right angles to the incident beam of light while sacrificing some of the resolution of features parallel to the direction of the beam.  Because of this orientation of the beam the relative refractive index of the particle and the mounting liquid becomes apparent.  The wavelengths for which the liquid has the higher refractive index are refracted into the front lens of the objective from the side of the particle nearest the side from which the light is coming.  If the particle has a higher refractive index for all visible wavelengths then this side of the particle is dark.  The side farthest from the source of the light shows all the wavelengths for which the particle has the higher refractive index.  These effects are seen with the particle in sharp focus.  This is a significant advantage over the Becke` line method because the particle doesn’t have to be defocus to see the colors and generally the colors are more distinct than are the Becke` line dispersion colors.  The colors seen with this type of dispersion staining are about the same as those with the Becke` Line method shown in Chart 1.  Examples of this type of dispersion staining and the colors shown for different λo’s can be seen at microlabgallery.com site for Becke` Line Dispersion Staining.  The presence of two colors helps to bracket the wavelength at which the refractive index matches for the two materials.

text: A smart key is available as an option coupled with two position memory seat that memorizes driver's seat positions and adjustments, exterior mirror adjustments, and climate control settings. The settings can be customized based on the smart key module being used to unlock and start the car. Turn signal repeaters are still integrated into the side exterior mirrors on all Japanese-spec models. The black leather interior installed on vehicles with the "S" package can be fitted with optional black corduroy inserts with white contrasting French stitching on all visible seams and aluminum cross drilled brake, clutch and accelerator pedals. The Legacy wagon can be fitted with twin white LED lights installed on the interior hatch vertically surrounding the rear window with a separate light switch for additional illumination when the rear hatch is open. An optional LED accessory lighting package in either white or blue can be installed for the front and rear passenger footwells and a matching illuminated sill panel for the front and rear doors, and the standard overhead dome light can be exchanged for white LED as well.

text: A

text: smart key

text: is available as an option coupled with two position memory seat that memorizes driver's seat positions and adjustments, exterior mirror adjustments, and climate control settings. The settings can be customized based on the smart key module being used to unlock and start the car. Turn signal repeaters are still integrated into the side exterior mirrors on all Japanese-spec models. The black leather interior installed on vehicles with the "S" package can be fitted with optional black

text: corduroy

text: inserts with white contrasting

text: French stitching

text: on all visible seams and aluminum cross drilled brake, clutch and accelerator pedals. The Legacy wagon can be fitted with twin white LED lights installed on the interior hatch vertically surrounding the rear window with a separate light switch for additional illumination when the rear hatch is open. An optional LED accessory lighting package in either white or blue can be installed for the front and rear passenger footwells and a matching illuminated sill panel for the front and rear doors, and the standard overhead

text: dome light

text: can be exchanged for white LED as well.

text: The context of a photogeochemical reaction is implicitly the surface of Earth, since that is where sunlight is available (although other sources of light such as chemiluminescence would not be strictly excluded from photogeochemical study). Reactions may occur among components of land such as rocks, soil and detritus; components of surface water such as sediment and dissolved organic matter; and components of the atmospheric boundary layer directly influenced by contact with land or water, such as mineral aerosols and gases. Visible and medium- to long-wave ultraviolet radiation is the main source of energy for photogeochemical reactions; wavelengths of light shorter than about 290 nm are completely absorbed by the present atmosphere, and are therefore practically irrelevant, except in consideration of atmospheres different from that of Earth today.

text: The context of a photogeochemical reaction is implicitly the surface of Earth, since that is where

text: sunlight

text: is available (although other sources of light such as

text: chemiluminescence

text: would not be strictly excluded from photogeochemical study). Reactions may occur among components of land such as

text: rocks

text: soil

text: and

text: detritus

text: ; components of

text: surface water

text: such as sediment and dissolved organic matter; and components of the

text: atmospheric boundary layer

text: directly influenced by contact with land or water, such as mineral

text: aerosol

text: s and gases.

text: Visible

text: and medium- to long-wave

text: ultraviolet

text: radiation is the main source of energy for photogeochemical reactions; wavelengths of light shorter than about 290 nm are completely absorbed by the present atmosphere, and are therefore practically irrelevant, except in consideration of atmospheres different from that of Earth today.

text: Critical illumination acts to form an image of the light source on the specimen to illuminate it. This image is formed by the condenser or collector lens. This illumination is bright but not always even, as any structure in the light source (for example the filament of a light bulb) will be visible in the resulting image. Homogenous light sources such as a flame or sunlight give more even illumination. Alternatively, a ground or opal glass diffuser can be used to homogenise the light source, but this will cause a significant amount of light to be scattered away from the sample.

text: Critical illumination acts to form an image of the light source on the specimen to illuminate it. This image is formed by the

text: condenser or collector lens

text: . This illumination is bright but not always even, as any structure in the light source (for example the filament of a

text: light bulb

text: ) will be visible in the resulting image. Homogenous light sources such as a

text: flame

text: or

text: sunlight

text: give more even illumination. Alternatively, a

text: ground

text: or

text: opal glass

text: diffuser can be used to homogenise the light source, but this will cause a significant amount of light to be scattered away from the sample.

text: In photography and stage lighting, the inverse-square law is used to determine the "fall off" or the difference in illumination on a subject as it moves closer to or further from the light source. For quick approximations, it is enough to remember that doubling the distance reduces illumination to one quarter; or similarly, to halve the illumination increase the distance by a factor of 1.4 (the square root of 2), and to double illumination, reduce the distance to 0.7 (square root of 1/2). When the illuminant is not a point source, the inverse square rule is often still a useful approximation; when the size of the light source is less than one-fifth of the distance to the subject, the calculation error is less than 1%.

text: In

text: photography

text: and

text: stage lighting

text: , the inverse-square law is used to determine the "fall off" or the difference in illumination on a subject as it moves closer to or further from the light source. For quick approximations, it is enough to remember that doubling the distance reduces illumination to one quarter; or similarly, to halve the illumination increase the distance by a factor of 1.4 (the

text: square root of 2

text: ), and to double illumination, reduce the distance to 0.7 (square root of 1/2). When the illuminant is not a point source, the inverse square rule is often still a useful approximation; when the size of the light source is less than one-fifth of the distance to the subject, the calculation error is less than 1%.

text: Illumination was a complex and frequently costly process. It was usually reserved for special books: an altar Bible, for example. Wealthy people often had richly illuminated "books of hours" made, which set down prayers appropriate for various times in the liturgical day.

text: Illumination was a complex and frequently costly process. It was usually reserved for special books: an altar Bible, for example. Wealthy people often had richly illuminated "

text: books of hours

text: " made, which set down prayers appropriate for various times in the

text: liturgical day

text: (1) Light no visible in the satellite view

text: Chappelle proved that the number of bacteria in water can be measured by the amount of light given off by that bacteria. He also showed how satellites can monitor luminescence levels to monitor crops (growth rates, water conditions and harvest timing). Emmett Chappelle married his highschool sweetheart, Rose Mary Phillips.

text: The total amount of artificial light (especially from street light) is sufficient for cities to be easily visible at night from the air, and from space.  This light is the source of light pollution that burdens astronomers and others.<center>

text: The total amount of artificial light (especially from

text: street light

text: ) is sufficient for cities to be easily visible at night from the air, and from space.  This light is the source of

text: light pollution

text: that burdens

text: astronomers

text: and others.<center>

text: Ultimately, other sources of illumination will have to be put to use, such as electron beams, x-rays or similar sources of electromagnetic energy with wavelengths much shorter than visible light.  However, in order to delay as long as possible the vast expense and difficulty of adopting a whole new type of illumination technology, manufacturers have turned to a technique, previously used in microscopes, for increasing the numerical aperture of the lens by allowing the light to pass through water instead of air. This method, called immersion lithography, is the current cutting edge of practical production technology.  It works because numerical aperture is a function of the maximum angle of light that can enter the lens and the refractive index of the medium through which the light passes. When water is employed as the medium, it greatly increases numerical aperture, since it has a refractive index of 1.44 at 193 nm, while air has an index of 1. Current production machines employing this technology are capable of resolving lines in the 32 nm range, and may eventually be able to achieve lines of 30 nm.

text: Ultimately, other sources of illumination will have to be put to use, such as

text: electron beam

text: s,

text: x-ray

text: s or similar sources of

text: electromagnetic

text: energy

text: with wavelengths much shorter than visible light.  However, in order to delay as long as possible the vast expense and difficulty of adopting a whole new type of illumination technology, manufacturers have turned to a technique, previously used in

text: microscope

text: s, for increasing the numerical aperture of the lens by allowing the light to pass through

text: water

text: instead of

text: air

text: . This method, called

text: immersion lithography

text: , is the current cutting edge of practical production technology.  It works because numerical aperture is a function of the maximum angle of light that can enter the lens and the

text: refractive index

text: of the medium through which the light passes. When water is employed as the medium, it greatly increases numerical aperture, since it has a refractive index of 1.44 at 193 nm, while air has an index of 1. Current production machines employing this technology are capable of resolving lines in the 32 nm range, and may eventually be able to achieve lines of 30 nm.

text: Incandescence is a special case of thermal radiation. Incandescence usually refers specifically to visible light, while thermal radiation refers also to infrared or any other electromagnetic radiation.

text: Incandescence is a special case of

text: thermal radiation

text: . Incandescence usually refers specifically to

text: visible light

text: , while thermal radiation refers also to

text: infrared

text: or any other

text: electromagnetic radiation

text: The captain of a 707 which was  behind the accident flight stated their descent was in instrument conditions until they broke out of the cloud layer at about 8,000 to 10,000 feet and approximately  east of the shoreline. The night visibility was "fuzzy and unclear", and lights on the shoreline were the only ones visible.

text: The captain of a

text: which was  behind the accident flight stated their descent was in instrument conditions until they broke out of the cloud layer at about 8,000 to 10,000 feet and approximately  east of the shoreline. The night visibility was "fuzzy and unclear", and lights on the shoreline were the only ones visible.

text: An electric light is a device that produces visible light by the flow of electric current. It is the most common form of artificial lighting and is essential to modern society, providing interior lighting for buildings and exterior light for evening and nighttime activities. In technical usage, a replaceable component that produces light from electricity is called a lamp. Compact lamps are commonly called light bulbs; for example, the incandescent light bulb. Lamps usually have a base made of ceramic, metal, glass or plastic, which secures the lamp in the socket of a light fixture. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap.

text: An electric light is a device that produces

text: visible light

text: by the flow of

text: electric current

text: . It is the most common form of

text: artificial lighting

text: and is essential to modern society, providing interior lighting for buildings and exterior light for evening and nighttime activities. In technical usage, a replaceable component that produces light from electricity is called a lamp. Compact lamps are commonly called light bulbs; for example, the

text: incandescent light bulb

text: . Lamps usually have a base made of ceramic, metal, glass or plastic, which secures the lamp in the socket of a

text: light fixture

text: . The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap.

text: 1. Biologic tissue is irradiated by an energy source that is absorbed by the body. The source of energy is non-specific, but typically consists of visible light, near infrared, radio waves or microwaves.

text: 1. Biologic tissue is irradiated by an energy source that is absorbed by the body. The source of energy is non-specific, but typically consists of

text: visible light

text: near infrared

text: radio waves

text: or

text: microwaves

text: Bobtail squid have  a symbiotic relationship with bioluminescent bacteria (Aliivibrio fischeri), which inhabit a special light organ in the squid's mantle. The bacteria are fed a sugar and amino acid solution by the squid and in return hide the squid's silhouette when viewed from below by matching the amount of light hitting the top of the mantle. The organ contains filters which may alter the wavelength of luminescence closer to that of downwelling moonlight and starlight; a lens with biochemical similarities to the squid's eye to diffuse the bacterial luminescence; and a reflector which directs the light ventrally.

text: Bobtail squid have  a

text: symbiotic

text: relationship with

text: bioluminescent

text: bacteria

text: Aliivibrio fischeri

text: ), which inhabit a special light organ in the squid's mantle. The bacteria are fed a sugar and amino acid solution by the squid and in return hide the squid's

text: silhouette

text: when viewed from below by matching the amount of light hitting the top of the mantle. The organ contains filters which may alter the

text: wavelength

text: of luminescence closer to that of downwelling

text: moonlight

text: and

text: starlight

text: ; a

text: lens

text: with

text: biochemical

text: similarities to the squid's eye to diffuse the bacterial luminescence; and a

text: reflector

text: which directs the light

text: ventral

text: ly.

text: In 1875, the light source was changed to Kerosene. In 1915, the station was transferred to the Commonwealth. The light was upgraded in 1917 and again in 1923. In one of these upgrades when the light source was converted to an incandescent mantle using vaporised kerosene.

text: In 1875, the light source was changed to

text: Kerosene

text: . In 1915, the station was transferred to the Commonwealth. The light was upgraded in 1917 and again in 1923. In one of these upgrades when the light source was converted to an incandescent mantle using vaporised kerosene.

text: The spectrum of light emitted from a fluorescent lamp is the combination of light directly emitted by the mercury vapor, and light emitted by the phosphorescent coating. The spectral lines from the mercury emission and the phosphorescence effect give a combined spectral distribution of light that is different from those produced by incandescent sources. The relative intensity of light emitted in each narrow band of wavelengths over the visible spectrum is in different proportions compared to that of an incandescent source. Colored objects are perceived differently under light sources with differing spectral distributions. For example, some people find the color rendition produced by some fluorescent lamps to be harsh and displeasing. A healthy person can sometimes appear to have an unhealthy skin tone under fluorescent lighting. The extent to which this phenomenon occurs is related to the light's spectral composition, and may be gauged by its color rendering index (CRI).

text: The spectrum of light emitted from a fluorescent lamp is the combination of light directly emitted by the mercury vapor, and light emitted by the phosphorescent coating. The

text: spectral line

text: s from the mercury emission and the phosphorescence effect give a combined spectral distribution of light that is different from those produced by incandescent sources. The relative intensity of light emitted in each narrow band of wavelengths over the visible spectrum is in different proportions compared to that of an incandescent source. Colored objects are perceived differently under light sources with differing spectral distributions. For example, some people find the color rendition produced by some fluorescent lamps to be harsh and displeasing. A healthy person can sometimes appear to have an unhealthy skin tone under fluorescent lighting. The extent to which this phenomenon occurs is related to the light's spectral composition, and may be gauged by its

text: color rendering index

text: (CRI).

text: One upconversion technique is to incorporate lanthanide-doped materials (, ,  or a combination), taking advantage of their luminescence to convert infrared radiation to visible light. Upconversion process occurs when two infrared photons are absorbed by rare-earth ions to generate a (high-energy) absorbable photon. As example, the energy transfer upconversion process (ETU), consists in successive transfer processes between excited ions in the near infrared. The upconverter material could be placed below the solar cell to absorb the infrared light that passes through the silicon. Useful ions are most commonly found in the trivalent state.  ions have been the most used.  ions absorb solar radiation around 1.54 µm. Two  ions that have absorbed this radiation can interact with each other through an upconversion process. The excited ion emits light above the Si bandgap that is absorbed by the solar cell and creates an additional electron–hole pair that can generate current. However, the increased efficiency was small. In addition, fluoroindate glasses have low phonon energy and have been proposed as suitable matrix doped with  ions.

text: One upconversion technique is to incorporate

text: lanthanide

text: -doped materials (

text: or a combination), taking advantage of their

text: luminescence

text: to convert

text: infrared radiation

text: to visible light. Upconversion process occurs when two

text: infrared

text: photons are absorbed by

text: rare-earth

text: ion

text: s to generate a (high-energy) absorbable photon. As example, the energy transfer upconversion process (ETU), consists in successive transfer processes between excited ions in the near infrared. The upconverter material could be placed below the solar cell to absorb the infrared light that passes through the silicon. Useful ions are most commonly found in the trivalent state.  ions have been the most used.  ions absorb solar radiation around 1.54 µm. Two  ions that have absorbed this radiation can interact with each other through an upconversion process. The excited ion emits light above the Si bandgap that is absorbed by the solar cell and creates an additional electron–hole pair that can generate current. However, the increased efficiency was small. In addition, fluoroindate glasses have low

text: phonon

text: energy and have been proposed as suitable matrix doped with  ions.

text: Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation.

text: Photoconductivity is an

text: optical

text: and

text: electrical phenomenon

text: in which a material becomes more

text: electrically conductive

text: due to the absorption of

text: electromagnetic radiation

text: such as

text: visible light

text: ultraviolet

text: light,

text: infrared

text: light, or

text: gamma radiation

text: Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. The most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can only be seen when exposed to UV light. Fluorescent materials cease to glow immediately when the radiation source stops, unlike phosphorescence, where it continues to emit light for some time after.

text: Fluorescence is the emission of

text: light

text: by a substance that has absorbed light or other

text: electromagnetic radiation

text: . It is a form of

text: luminescence

text: . In most cases, the emitted light has a longer

text: wavelength

text: , and therefore lower energy, than the absorbed radiation. The most striking example of fluorescence occurs when the absorbed radiation is in the

text: ultraviolet

text: region of the

text: spectrum

text: , and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can only be seen when exposed to

text: UV light

text: . Fluorescent materials cease to glow immediately when the radiation source stops, unlike

text: phosphorescence

text: , where it continues to emit light for some time after.

text: An ultramicroscope is a microscope with a system of illumination that allows viewing of tiny particles. When the diameter of a particle is below or near the wavelength of visible light (around 500 nanometers), the particle cannot be seen in a light microscope with the usual method of illumination. The ultramicroscope system is based on light scattering, not light reflection.

text: An ultramicroscope is a

text: microscope

text: with a system of illumination that allows viewing of tiny particles. When the diameter of a particle is below or near the

text: wavelength

text: of

text: visible light

text: (around 500

text: nanometer

text: s), the particle cannot be seen in a

text: light microscope

text: with the usual method of illumination. The ultramicroscope system is based on

text: light scattering

text: , not

text: light reflection

text: A black light may also be formed by simply using Wood's glass as the envelope for a common incandescent bulb. This was the method that was used to create the very first black light sources. Although incandescent black light bulbs are a cheaper alternative to fluorescent tubes, they are exceptionally inefficient at producing UV light since most of the light emitted by the filament is visible light which must be blocked. Due to its black body spectrum, an incandescent light radiates less than 0.1% of its energy as UV light. Incandescent UV bulbs, due to the necessary absorption of the visible light, become very hot during use. This heat is, in fact, encouraged in such bulbs, since a hotter filament increases the proportion of UVA in the black-body radiation emitted. This high running-temperature drastically reduces the life of the lamp, however, from a typical 1000 hours to around 100 hours.

text: A black light may also be formed by simply using

text: Wood's glass

text: as the envelope for a common

text: incandescent bulb

text: . This was the method that was used to create the very first black light sources. Although incandescent black light bulbs are a cheaper alternative to fluorescent tubes, they are exceptionally inefficient at producing UV light since most of the light emitted by the filament is visible light which must be blocked. Due to its

text: black body

text: spectrum, an incandescent light radiates less than 0.1% of its energy as UV light. Incandescent UV bulbs, due to the necessary absorption of the visible light, become very hot during use. This heat is, in fact, encouraged in such bulbs, since a hotter filament increases the proportion of UVA in the black-body radiation emitted. This high running-temperature drastically reduces the life of the lamp, however, from a typical 1000 hours to around 100 hours.

text: Live green plants absorb solar radiation in the photosynthetically active radiation (PAR) spectral region, which they use as a source of energy in the process of photosynthesis. Leaf cells have also evolved to re-emit solar radiation in the near-infrared spectral region (which carries approximately half of the total incoming solar energy), because the photon energy at wavelengths longer than about 700 nanometers is not large enough to synthesize organic molecules. A strong absorption at these wavelengths would only result in overheating the plant and possibly damaging the tissues. Hence, live green plants appear relatively dark in the PAR and relatively bright in the near-infrared. By contrast, clouds and snow tend to be rather bright in the red (as well as other visible wavelengths) and quite dark in the near-infrared.The pigment in plant leaves, chlorophyll, strongly absorbs visible light (from 0.4 to 0.7 µm) for use in photosynthesis. The cell structure of the leaves, on the other hand, strongly reflects near-infrared light (from 0.7 to 1.1 µm). The more leaves a plant has, the more these wavelengths of light are affected, respectively.Since early instruments of Earth Observation, such as NASA's ERTS and NOAA's AVHRR, acquired data in visible and near-infrared, it was natural to exploit the strong differences in plant reflectance to determine their spatial distribution in these satellite images.

text: Live green plants absorb solar radiation in the

text: photosynthetically active radiation

text: (PAR) spectral region, which they use as a source of energy in the process of

text: photosynthesis

text: . Leaf cells have also evolved to re-emit solar radiation in the near-infrared spectral region (which carries approximately half of the total incoming solar energy), because the photon energy at wavelengths longer than about 700 nanometers is not large enough to synthesize organic molecules. A strong absorption at these wavelengths would only result in overheating the plant and possibly damaging the tissues. Hence, live green plants appear relatively dark in the PAR and relatively bright in the near-infrared. By contrast, clouds and snow tend to be rather bright in the red (as well as other visible wavelengths) and quite dark in the near-infrared.The pigment in plant leaves, chlorophyll, strongly absorbs visible light (from 0.4 to 0.7 µm) for use in photosynthesis. The cell structure of the leaves, on the other hand, strongly reflects near-infrared light (from 0.7 to 1.1 µm). The more leaves a plant has, the more these wavelengths of light are affected, respectively.Since early instruments of Earth Observation, such as

text: NASA

text: 's ERTS and

entity_name: National Oceanic and Atmospheric Administration

text: NOAA

text: 's AVHRR, acquired data in visible and near-infrared, it was natural to exploit the strong differences in plant reflectance to determine their spatial distribution in these satellite images.

text: When a CFL is dimmed, its color temperature (warmth) stays the same. This is counter to most other light sources (such as the sun or incandescents) where color gets redder as the light source gets dimmer. The Kruithof curve from 1934 described an empirical relationship between intensity and color temperature of visually pleasing light sources.

text: When a CFL is dimmed, its color temperature (warmth) stays the same. This is counter to most other light sources (such as the sun or incandescents) where color gets redder as the light source gets dimmer. The

text: Kruithof curve

text: from 1934 described an empirical relationship between intensity and color temperature of visually pleasing light sources.

text: The color rendering index (CRI) of a light source is a quantitative measure of its ability to reproduce the colors of various objects faithfully in comparison with an ideal or natural light source. In general terms, CRI is a measure of a light source's ability to show object colors "realistically" or "naturally" compared to a familiar reference source, either incandescent light or daylight. It is significant because it has been the most difficult metric for incandescent replacement light bulbs to match (while maintaining high efficiency) and therefore the most frequently ignored (the CRI spec value appears on only a very small percentage of LED product packaging). For that reason, LED light bulbs with a high CRI can be worthy replacements for incandescent light bulbs. Most LED lights do not have a CRI above 90. For example, the top bulbs listed in the 2016 Best LED Lights Consumer Review only have a CRI of 80.

text: The

text: color rendering index

text: (CRI) of a

text: light

text: source is a quantitative measure of its ability to reproduce the colors of various objects faithfully in comparison with an ideal or natural light source. In general terms, CRI is a measure of a light source's ability to show object colors "realistically" or "naturally" compared to a familiar reference source, either incandescent light or daylight. It is significant because it has been the most difficult metric for incandescent replacement

text: light bulb

text: s to match (while maintaining high efficiency) and therefore the most frequently ignored (the CRI spec value appears on only a very small percentage of LED product packaging). For that reason, LED light bulbs with a high CRI can be worthy replacements for incandescent light bulbs. Most LED lights do not have a CRI above 90. For example, the top bulbs listed in the 2016 Best LED Lights Consumer Review only have a CRI of 80.

text: All the major features of fluorescent lighting were in place at the end of the 1920s. Decades of invention and development had provided the key components of fluorescent lamps: economically manufactured glass tubing, inert gases for filling the tubes, electrical ballasts, long-lasting electrodes, mercury vapor as a source of luminescence, effective means of producing a reliable electrical discharge, and fluorescent coatings that could be energized by ultraviolet light. At this point, intensive development was more important than basic research.

text: Since the release of the Source Four, other lighting manufacturers have since revised their products to compete in the market share alongside the ETC. The Selecon Pacific, an L shaped ERS, has an irregular shape due to an integrated dichroic cold mirror, which effectively splits the visible wavelengths of the light beam from the infrared, allowing the heat to be drawn off by a heat sink and away from the instrument. This keeps the beam of the fixture cool allowing for the use of plastic gobos. The beam also improves shutter, gobo and color gel life, and can improve the temperature on stage. Altman Lighting released their Shakespeare line of units in 1994 as a response to the Source Four. One improvement over the Source Four is a wider range of adjustment in regards to rotation of the barrel assembly. The patents for some components in this unit have been licensed from ETC.

text: Since the release of the Source Four, other lighting manufacturers have since revised their products to compete in the market share alongside the ETC. The Selecon Pacific, an L shaped ERS, has an irregular shape due to an integrated dichroic

text: cold mirror

text: , which effectively splits the visible wavelengths of the light beam from the infrared, allowing the heat to be drawn off by a heat sink and away from the instrument. This keeps the beam of the fixture cool allowing for the use of plastic gobos. The beam also improves shutter, gobo and color gel life, and can improve the temperature on stage.

text: Altman Lighting

text: released their Shakespeare line of units in 1994 as a response to the Source Four. One improvement over the Source Four is a wider range of adjustment in regards to rotation of the barrel assembly. The patents for some components in this unit have been licensed from ETC.

text: The light characteristic shown is one flash every five seconds, white/red depending on sector (Fl.W.R. 5s). White is shown 005°-307°, visible for . Red is shown 307°-005°, visible for . The light source is a 120 Volt tungsten-halogen lamp, fed from diesel alternators.

text: The

text: light characteristic

text: shown is one flash every five seconds, white/red depending on sector (Fl.W.R. 5s). White is shown 005°-307°, visible for . Red is shown 307°-005°, visible for . The light source is a 120

text: Volt

text: tungsten-halogen lamp

text: , fed from

text: diesel alternator

text: s.

text: Architectural lighting design focuses on three fundamental aspects of the illumination of buildings or spaces. The first is the aesthetic appeal of a building, an aspect particularly important in the illumination of retail environments. Secondly, the ergonomic aspect: the measure of how much of a function the lighting plays.  Thirdly is the energy efficiency issue to ensure that light is not wasted by over-illumination, either by illuminating vacant spaces unnecessarily or by providing more light than needed for the aesthetics or the task.

text: Architectural lighting design focuses on three fundamental aspects of the illumination of buildings or spaces. The first is the aesthetic appeal of a building, an aspect particularly important in the illumination of

text: retail

text: environments. Secondly, the

text: ergonomic

text: aspect: the measure of how much of a function the lighting plays.  Thirdly is the

text: energy efficiency

text: issue to ensure that light is not wasted by

text: over-illumination

text: , either by illuminating vacant spaces unnecessarily or by providing more light than needed for the

text: aesthetics

text: or the task.

text: Blue light, also known as high-energy visible (HEV) light, has been shown to impair human sleep cycles by suppressing the production of melatonin, a hormone that enables people to fall asleep. Common sources of blue light include screens found on laptops, tablets, and smartphones.

text: Blue light, also known as high-energy visible (HEV) light, has been shown to impair human sleep cycles by suppressing the production of

text: melatonin

text: , a

text: hormone

text: that enables people to fall asleep. Common sources of blue light include screens found on

text: laptop

text: s,

text: tablets

text: , and

text: smartphone

text: s.

text: Photographic lighting is the illumination of scenes to be photographed. A photograph simply records patterns of light, colour, and shade; lighting is all-important in controlling the image. In many cases even illumination is desired to give an accurate rendition of the scene. In other cases the direction, brightness, and colour of light are manipulated for effect. Lighting is particularly important for monochrome photography, where there is no colour information, only the interplay of highlights and shadows. Lighting and exposure are used to create effects such as low-key and high-key.

text: Photographic lighting is the illumination of scenes to be

text: photographed

text: . A photograph simply records patterns of light, colour, and shade; lighting is all-important in controlling the image. In many cases even illumination is desired to give an accurate rendition of the scene. In other cases the direction, brightness, and colour of light are manipulated for effect. Lighting is particularly important for

text: monochrome

text: photography, where there is no colour information, only the interplay of

text: highlights

text: and

text: shadow

text: s. Lighting and

text: exposure

text: are used to create effects such as

text: low-key

text: and

text: high-key

text: Communications towers that are lighted at night for aviation safety may help reduce bird collisions caused by poor visibility, but they bring about a second, even more deadly mechanism for mortality. When there is a low cloud ceiling, hazy or foggy conditions, lights on a tower reflect off water or other particles in the air creating an illuminated area around the tower. Migrating birds lose their stellar cues for nocturnal migration in such conditions. In addition, they often lose any broad orienting perspective they might have had on the landscape. When passing the lighted area, it may be that the increased visibility around the tower becomes the strongest cue the birds have for navigation, and thus they tend to remain in the lighted space near the tower, afraid to leave. Mortality occurs when they run into the structure and its guy wires, or even other migrating birds as more and more passing birds aggregate in the relatively small, lighted space. It is important to clarify that the lights are not documented to attract birds from afar, but appear to hold birds that fly into the illuminated vicinity. Lights are required by the FCC on any tower taller than , or on shorter towers if they are near airports. In 2008, it was estimated there were roughly 125,000 lit towers in the U.S. and more than 7,000 new towers are constructed each year.

text: values per measurement. Spectroscopic ellipsometry (SE) employs broad band light sources, which cover a certain spectral range in the infrared, visible or ultraviolet spectral region. By that the complex refractive index or the dielectric function tensor in the corresponding spectral region can be obtained, which gives access to a large number of fundamental physical properties. Infrared spectroscopic ellipsometry (IRSE) can probe lattice vibrational (phonon) and free charge carrier (plasmon) properties. Spectroscopic ellipsometry in the near infrared, visible up to ultraviolet spectral region studies the refractive index in the transparency or below-band-gap region and electronic properties, for instance, band-to-band transitions or excitons.

text: values per measurement. Spectroscopic ellipsometry (SE) employs broad band

text: light source

text: s, which cover a certain spectral range in the

text: infrared

text: , visible or

text: ultraviolet

text: spectral region. By that the complex

text: refractive index

text: or the

text: dielectric function

text: tensor in the corresponding spectral region can be obtained, which gives access to a large number of fundamental physical properties. Infrared spectroscopic ellipsometry (IRSE) can probe lattice vibrational (

text: phonon

text: ) and free

text: charge carrier

text: plasmon

text: ) properties. Spectroscopic ellipsometry in the near infrared, visible up to ultraviolet spectral region studies the

text: refractive index

text: in the transparency or below-

text: band-gap

text: region and electronic properties, for instance, band-to-band transitions or

text: exciton

text: s.

text: In August 1893 August Köhler developed Köhler illumination. This method of sample illumination gives rise to extremely even lighting and overcomes many limitations of older techniques of sample illumination. Before development of Köhler illumination the image of the light source, for example a lightbulb filament, was always visible in the image of the sample.

text: In August 1893

text: August Köhler

text: developed

text: Köhler illumination

text: . This method of sample illumination gives rise to extremely even lighting and overcomes many limitations of older techniques of sample illumination. Before development of Köhler illumination the image of the light source, for example a

text: lightbulb

text: filament, was always visible in the image of the sample.

text: An incandescent light bulb, modulated by pulsing the current powering the filament or by a mechanical chopper. For systems used outdoors, it is difficult for an incandescent source to compete with the intensity of sunlight when the sun shines directly into the receiver. Also, it is difficult to achieve modulation frequencies distinguishable from those that can be produced naturally, for instance by heat shimmer or by sunlight reflecting off waves at sea.

text: An

text: incandescent light bulb

text: , modulated by pulsing the current powering the filament or by a mechanical

text: chopper

text: . For systems used outdoors, it is difficult for an incandescent source to compete with the intensity of

text: sunlight

text: when the sun shines directly into the receiver. Also, it is difficult to achieve modulation frequencies distinguishable from those that can be produced naturally, for instance by

text: heat shimmer

text: or by sunlight reflecting off waves at sea.

text: The Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus. It constitutes the visible portions of the Cygnus Loop (radio source W78, or Sharpless 103), a large but relatively faint supernova remnant. The source supernova exploded circa 3,000 BC to 6,000 BC, and the remnants have since expanded to cover an area roughly 3 degrees in diameter (about 6 times the diameter, or 36 times the area, of the full moon). The distance to the nebula is not precisely known, but Far Ultraviolet Spectroscopic Explorer (FUSE) data supports a distance of about 1,470 light-years.

text: The Veil Nebula is a cloud of heated and ionized gas and dust in the

text: constellation

text: Cygnus

text: . It constitutes the visible portions of the

text: Cygnus Loop

text: (radio source W78, or Sharpless 103), a large but relatively faint

text: supernova remnant

text: . The source

text: supernova

text: exploded circa 3,000 BC to 6,000 BC, and the remnants have since expanded to cover an area roughly 3 degrees in diameter (about 6 times the diameter, or 36 times the area, of the full moon). The distance to the nebula is not precisely known, but

text: Far Ultraviolet Spectroscopic Explorer

text: (FUSE) data supports a distance of about 1,470

text: light-years

text: The rear registration plate is illuminated by a white lamp designed to light the surface of the plate without creating white light directly visible to the rear of the vehicle; it must be illuminated whenever the position lamps are lit.

text: The rear

text: registration plate

text: is illuminated by a white lamp designed to light the surface of the plate without creating white light directly visible to the rear of the vehicle; it must be illuminated whenever the position lamps are lit.

text: Under certain conditions, window film will exhibit iridescence. This phenomenon usually occurs at night, when the source of illumination within a building is fluorescent lighting. The amount of iridescence may vary from almost imperceptible to very visible. It most frequently occurs when the film is constructed with scratch resistance protection. When iridescence does occur in window film, the best way to stop it is to prevent the fluorescent light from illuminating the film or to use an alternative type of light.

text: Under certain conditions, window film will exhibit

text: iridescence

text: . This phenomenon usually occurs at night, when the source of illumination within a building is fluorescent lighting. The amount of iridescence may vary from almost imperceptible to very visible. It most frequently occurs when the film is constructed with scratch resistance protection. When iridescence does occur in window film, the best way to stop it is to prevent the fluorescent light from illuminating the film or to use an alternative type of light.

text: The deep sea starts at the aphotic zone, the point where sunlight loses most of its energy in the water. Many life forms that live at these depths have the ability to create their own light a unique evolution known as bio-luminescence.

text: The

text: deep sea

text: starts at the

text: aphotic zone

text: , the point where sunlight loses most of its energy in the water. Many life forms that live at these depths have the ability to create their own light a unique evolution known as

text: bio-luminescence

text: To illuminate a particular cell, the electrodes that intersect at the cell are charged by control circuitry and electric current flows through the cell, stimulating the gas (typically xenon and neon) atoms inside the cell. These ionized gas atoms, or plasmas, then release ultraviolet photons that interact with a phosphor material on the inside wall of the cell. The phosphor atoms are stimulated and electrons jump to higher energy levels. When these electrons return to their natural state, energy is released in the form of visible light. Every pixel on the display is made up of three subpixel cells. One subpixel cell is coated with red phosphor, another is coated with green phosphor, and the third cell is coated with blue phosphor. Light emitted from the subpixel cells is blended together to create an overall color for the pixel. The control circuitry can manipulate the intensity of light emitted from each cell, and therefore can produce a large gamut of colors. Light from each cell can be controlled and changed rapidly to produce a high-quality moving picture.

text: To illuminate a particular cell, the electrodes that intersect at the cell are charged by control circuitry and electric current flows through the cell, stimulating the gas (typically

text: xenon

text: and

text: neon

text: ) atoms inside the cell. These ionized gas atoms, or plasmas, then release

text: ultraviolet

text: photons that interact with a

text: phosphor

text: material on the inside wall of the cell. The phosphor atoms are stimulated and electrons jump to higher energy levels. When these electrons return to their natural state, energy is released in the form of visible light. Every pixel on the display is made up of three subpixel cells. One subpixel cell is coated with red phosphor, another is coated with green phosphor, and the third cell is coated with blue phosphor. Light emitted from the subpixel cells is blended together to create an overall color for the pixel. The control circuitry can manipulate the intensity of light emitted from each cell, and therefore can produce a large gamut of colors. Light from each cell can be controlled and changed rapidly to produce a high-quality moving picture.

text: Light, or visible light, is a very narrow range of electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm), or up to 380–750 nm. More broadly, physicists refer to light as electromagnetic radiation of all wavelengths, whether visible or not.

text: Plato makes the claim that "sight and the visible realm are deficient." He argues that for the other senses to be used all that is needed is the sense itself and that which can be sensed by it (e.g., to taste sweetness, one needs the sense of taste and that which can be tasted as sweet), but "even if a person's eyes are capable of sight, and he's trying to use it, and what he's trying to look at is coloured, the sight will see nothing and the colours will remain unseen, surely, unless there is also present an extra third thing which is made specifically for this purpose." The third thing Plato is talking about is light. Through this analogy he equates that which gives us natural light, the sun, as the source of goodness in this world.

text: As interest in conducting plastics grew, fluorene again found application. The aromatic nature of fluorene makes it an excellent candidate component of a conducting polymer because it can stabilize and conduct a charge; in the early 1980s fluorene was electropolymerized into conjugated polymer films with conductivities of 10 S cm.The optical properties (such as variable luminescence and visible light spectrum absorption) that accompany the extended conjugation in polymers of fluorene have become increasingly attractive for device applications. Throughout the 1990s and into the 2000s, many devices such as organic light-emitting diodes (OLEDs), organic solar cells., organic thin film transistors, and biosensors have all taken advantage of the luminescent, electronic and absorptive properties of polyfluorenes.

text: As interest in conducting plastics grew, fluorene again found application. The

text: aromatic

text: nature of fluorene makes it an excellent candidate component of a conducting polymer because it can stabilize and

text: conduct

text: a charge; in the early 1980s fluorene was electropolymerized into conjugated polymer films with conductivities of 10 S cm.The optical properties (such as variable

text: luminescence

text: and visible light spectrum absorption) that accompany the extended conjugation in polymers of fluorene have become increasingly attractive for device applications. Throughout the 1990s and into the 2000s, many devices such as

text: organic light-emitting diode

text: s (OLEDs),

text: organic solar cell

text: s.,

text: organic thin film transistors

text: , and

text: biosensors

text: have all taken advantage of the luminescent, electronic and absorptive properties of polyfluorenes.

text: Most nebulae can be described as diffuse nebulae, which means that they are extended and contain no well-defined boundaries.  Diffuse nebulae can be divided into emission nebula, reflection nebulae and "dark nebulae." In visible light nebulae may be divided into emission nebulae that emit spectral line radiation from excited or ionized gas (mostly ionized hydrogen);  they are often called HII regions (the term "HII"  refers to ionized hydrogen). Reflection nebulae are visible primarily due to the light they reflect. Reflection nebulae themselves do not emit significant amounts of visible light, but are near stars and reflect light from them. Similar nebulae not illuminated by stars do not exhibit visible radiation, but may be detected as opaque clouds blocking light from luminous objects behind them; they are called "dark nebulae".

text: Most nebulae can be described as diffuse nebulae, which means that they are extended and contain no well-defined boundaries.  Diffuse nebulae can be divided into

text: emission nebula

text: reflection nebula

text: e and "dark nebulae." In visible light nebulae may be divided into emission nebulae that emit

text: spectral line

text: radiation from excited or

text: ion

text: ized gas (mostly ionized

text: hydrogen

text: );  they are often called

text: HII regions

text: (the term "HII"  refers to ionized hydrogen).

text: Reflection nebula

text: e are visible primarily due to the light they reflect. Reflection nebulae themselves do not emit significant amounts of visible light, but are near stars and reflect light from them. Similar nebulae not illuminated by stars do not exhibit visible radiation, but may be detected as opaque clouds blocking light from luminous objects behind them; they are called "dark nebulae".

text: Incandescent lighting and even limelight were the first light sources used in film projection.  In the early 1900s up until the late 1960s, carbon arc lamps were the source of light in almost all theaters in the world.

text: Incandescent lighting

text: and even

text: limelight

text: were the first light sources used in film projection.  In the early 1900s up until the late 1960s,

text: carbon arc lamps

text: were the source of light in almost all theaters in the world.

text: Typically a short duration ultraviolet lamp or laser source illuminates the phosphor coating which in turn luminesces visibly. When the illuminating source ceases, the luminescence will persist for a characteristic time, steadily decreasing. The time required for the brightness to decrease to 1/e of its original value is known as the decay time or lifetime and signified as

text: Typically a short duration

text: ultraviolet

text: lamp or

text: laser

text: source illuminates the phosphor coating which in turn luminesces visibly. When the illuminating source ceases, the luminescence will persist for a characteristic time, steadily decreasing. The time required for the brightness to decrease to

text: of its original value is known as the decay time or lifetime and signified as

text: As f-f transitions are Laporte-forbidden, once an electron has been excited, decay to the ground state will be slow. This makes them suitable for use in lasers as it makes the population inversion easy to achieve. The Nd:YAG laser is one that is widely used. Europium-doped yttrium vanadate was the first red phosphor to enable the development of color television screens. Lanthanide ions have notable luminescent properties due to their unique 4f orbitals. Laporte forbidden f-f transitions can be activated by excitation of a bound "antenna" ligand. This leads to sharp emission bands throughout the visible, NIR, and IR and relatively long luminescence lifetimes.

text: As f-f transitions are Laporte-forbidden, once an electron has been excited, decay to the ground state will be slow. This makes them suitable for use in

text: laser

text: s as it makes the

text: population inversion

text: easy to achieve. The

text: Nd:YAG laser

text: is one that is widely used. Europium-doped yttrium vanadate was the first

text: red phosphor

text: to enable the development of color television screens. Lanthanide ions have notable luminescent properties due to their unique 4f orbitals. Laporte forbidden f-f transitions can be activated by excitation of a bound "antenna" ligand. This leads to sharp emission bands throughout the visible, NIR, and IR and relatively long luminescence lifetimes.

text: However, Tsang's plan to give each household a 100 Hong Kong dollar (US$13) voucher in February to buy fluorescent bulbs aroused controversy. The plan will be funded by Hong Kong's two major electricity companies, and paid for ultimately by the consumer - the utilities will be granted 50 and 60 HK cents increases per kilowatt-hour of electricity. Ming Pao Daily News and Apple Daily sparked allegations of conflict of interests when they reported that the new policy may benefit Tsang's son's father-in-law, Mok Kam-tsuen, a Hong Kong distributor for Philips light bulbs.Tsang said that he was aiming to safeguard public interests, and denied there was any conflict of interest. A spokesman for Mok's company said they had never heard about the scheme before the policy address. Mr Mok also issued a statement, clarifying that his business has not monopolized the market, since his company also sells incandescent conventional light bulbs. In other words, any potential benefit that may be generated by the new policy will be offset by corresponding loss in the incandescent conventional light bulbs market. Lawmakers from across the political spectrum did not question Tsang's integrity.

text: However, Tsang's plan to give each household a 100 Hong Kong dollar (US$13) voucher in February to buy fluorescent bulbs aroused controversy. The plan will be funded by Hong Kong's two major electricity companies, and paid for ultimately by the consumer - the utilities will be granted 50 and 60 HK cents increases per kilowatt-hour of electricity.

text: Ming Pao Daily News

text: and

text: Apple Daily

text: sparked allegations of conflict of interests when they reported that the new policy may benefit Tsang's son's father-in-law, Mok Kam-tsuen, a Hong Kong distributor for Philips light bulbs.Tsang said that he was aiming to safeguard public interests, and denied there was any conflict of interest. A spokesman for Mok's company said they had never heard about the scheme before the policy address. Mr Mok also issued a statement, clarifying that his business has not monopolized the market, since his company also sells incandescent conventional light bulbs. In other words, any potential benefit that may be generated by the new policy will be offset by corresponding loss in the incandescent conventional light bulbs market. Lawmakers from across the political spectrum did not question Tsang's integrity.

text: Luminescence: The Journal of Biological and Chemical Luminescence is a bimonthly peer-reviewed scientific journal publishing original scientific papers, short communications, technical notes, and reviews on fundamental and applied aspects of all forms of luminescence, including bioluminescence, chemiluminescence, electrochemiluminescence, sonoluminescence, triboluminescence, fluorescence, time-resolved fluorescence, and phosphorescence. The current editor-in-chief is L.J. Kricka (University of Pennsylvania). It was established in 1986 by John Wiley & Sons as the Journal of Bioluminescence and Chemiluminescence and obtained its current title in 1999.

text: Luminescence: The Journal of Biological and Chemical Luminescence is a bimonthly

text: peer-reviewed

text: scientific journal

text: publishing original scientific papers, short communications, technical notes, and reviews on fundamental and applied aspects of all forms of

text: luminescence

text: , including

text: bioluminescence

text: chemiluminescence

text: electrochemiluminescence

text: sonoluminescence

text: triboluminescence

text: fluorescence

text: , time-resolved fluorescence, and

text: phosphorescence

text: . The current

text: editor-in-chief

text: is

text: L.J. Kricka

text: University of Pennsylvania

text: ). It was established in 1986 by

text: John Wiley & Sons

text: as the Journal of Bioluminescence and Chemiluminescence and obtained its current title in 1999.

text: With conventional microscopy techniques, it is not possible to distinguish features that are located at distances less than about half the wavelength used (i.e. about 200 nm for visible light). This diffraction limit is based on the wave nature of light. In conventional microscopes the limit is determined by the used wavelength and the numerical aperture of the optical system. The RESOLFT concept surmounts this limit by temporarily switching the molecules to a state in which they cannot send a (fluorescence-) signal upon illumination. This concept is different from for example electron microscopy where instead the used wavelength is much smaller.

text: With conventional

text: microscopy

text: techniques, it is not possible to distinguish features that are located at distances less than about half the

text: wavelength

text: used (i.e. about 200 nm for

text: visible light

text: ). This

text: diffraction limit

text: is based on the wave nature of

text: light

text: . In conventional microscopes the limit is determined by the used wavelength and the

text: numerical aperture

text: of the optical system. The RESOLFT concept surmounts this limit by temporarily switching the molecules to a state in which they cannot send a (fluorescence-) signal upon illumination. This concept is different from for example

text: electron microscopy

text: where instead the used wavelength is much smaller.

text: For a fixed power and life, the luminous efficacy of all incandescent lamps is greatest at a particular design voltage. Halogen lamps made for 12 to 24 volt operation have good light outputs, and the very compact filaments are particularly beneficial for optical control (see picture). The ranges of multifaceted reflector "MR" lamps of 20–50 watts were originally conceived for the projection of 8 mm film, but are now widely used for display lighting and in the home. More recently, wider beam versions have become available designed for direct use on supply voltages of 120 or .

text: For a fixed power and life, the

text: luminous efficacy

text: of all incandescent lamps is greatest at a particular design voltage. Halogen lamps made for 12 to 24 volt operation have good light outputs, and the very compact filaments are particularly beneficial for optical control (see picture). The ranges of

text: multifaceted reflector

text: "MR" lamps of 20–50 watts were originally conceived for the projection of

text: 8 mm film

text: , but are now widely used for display lighting and in the home. More recently, wider beam versions have become available designed for direct use on supply voltages of 120 or .

text: The light from an incandescent source is similar in character to that from a Planckian "black body" in spectral distribution, that is, the bulb, as the filament heats up, produces light from wavelengths throughout the visible spectrum. Alternative light sources use phosphors or combinations of mono-chromatic LEDs (red, blue, green) to produce "white" light, giving significantly irregular spectral distributions which can result in color casts in photography and differences of color matching when compared to incandescent light or daylight.

text: The light from an incandescent source is similar in character to that from a

text: Planckian "black body"

text: in spectral distribution, that is, the bulb, as the filament heats up, produces light from wavelengths throughout the visible spectrum. Alternative light sources use phosphors or combinations of mono-chromatic LEDs (red, blue, green) to produce "white" light, giving significantly irregular spectral distributions which can result in color casts in photography and differences of color matching when compared to incandescent light or daylight.

text: Luminous efficacy of a light source may be defined in two ways. The radiant luminous efficacy (LER) is the ratio of the visible light flux emitted (the luminous flux) to the total power radiated over all wavelengths. The source luminous efficacy (LES) is the ratio of the visible light flux emitted (the luminous flux) to the total power input to the source, such as a lamp. Visible light is measured in lumens, a unit which is defined in part by the differing sensitivity of the human eye to different wavelengths of light. Not all wavelengths of visible electromagnetic energy are equally effective at stimulating the human eye; the luminous efficacy of radiant energy (LER) is a measure of how well the distribution of energy matches the perception of the eye. The units of luminous efficacy are "lumens per watt" (lpw). The maximum LER possible is 683 lm/W for monochromatic green light at 555 nanometers wavelength, the peak sensitivity of the human eye.

text: Luminous efficacy

text: of a light source may be defined in two ways. The radiant luminous efficacy (LER) is the ratio of the visible light flux emitted (the luminous flux) to the total power radiated over all wavelengths. The source luminous efficacy (LES) is the ratio of the visible light flux emitted (the luminous flux) to the total power input to the source, such as a lamp. Visible light is measured in

text: lumens

text: , a unit which is defined in part by the differing sensitivity of the human eye to different wavelengths of light. Not all wavelengths of visible electromagnetic energy are equally effective at stimulating the human eye; the luminous efficacy of radiant energy (LER) is a measure of how well the distribution of energy matches the perception of the eye. The units of luminous efficacy are "lumens per watt" (lpw). The maximum LER possible is 683 lm/W for monochromatic green light at 555 nanometers wavelength, the peak sensitivity of the human eye.

text: Consumers are often poorly informed of the savings of energy efficient products.  A prominent example of this is the energy savings that can be made by replacing an incandescent light bulb with a more modern alternative.  When purchasing light bulbs, many consumers opt for cheap incandescent bulbs, failing to take into account their higher energy costs and lower lifespans when compared to modern compact fluorescent and LED bulbs.  Although these energy-efficient alternatives have a higher upfront cost, their long lifespan and low energy use can save consumers a considerable amount of money.  The price of LEDs has also been steadily decreasing in the past five years, due to improvement of the semiconductor technology.  Many LED bulbs on the market qualify for utility rebates that further reduce the price of purchase to the consumer. Estimates by the U.S. Department of Energy state that widespread adoption of LED lighting over the next 20 years could result in about $265 billion worth of savings in United States energy costs.

text: Consumers are often poorly informed of the savings of energy efficient products.  A prominent example of this is the energy savings that can be made by replacing an

text: incandescent light bulb

text: with a more modern alternative.  When purchasing light bulbs, many consumers opt for cheap incandescent bulbs, failing to take into account their higher energy costs and lower lifespans when compared to modern

text: compact fluorescent

text: and

text: LED bulbs

text: .  Although these energy-efficient alternatives have a higher upfront cost, their long lifespan and low energy use can save consumers a considerable amount of money.  The price of LEDs has also been steadily decreasing in the past five years, due to improvement of the semiconductor technology.  Many LED bulbs on the market qualify for utility rebates that further reduce the price of purchase to the consumer. Estimates by the U.S. Department of Energy state that widespread adoption of LED lighting over the next 20 years could result in about $265 billion worth of savings in United States energy costs.

text: AI-2 was first discovered in the light producing system of the bacteria Vibrio harveyi. The pathway that induces Vibrio harveyi luminescence is controlled by two parallel pathways. The first pathway uses a typical AI-1 homoserine lactone signaling molecule. However the bacteria were also found to recognize a second auto inducer AI-2. Scientist also found that V. harveyi luminescence could be induced by 75 other bacterial species AI-2 molecules.This discovery led to the proposal of AI-2 as a universal form of communication between bacteria species. In addition to information about cell densities AI-2 can provide information on the growth phase and prosperity of cells in a population. It has a greater ability to store information than other quorum sensing molecules because its production is tied to cell growth. The production of AI-2 peaks in late log phase for many bacteria. The structure of AI-2 was discovered recently to be a fused 2-member ring with boron bridging the gap between the diesters.

text: AI-2 was first discovered in the light producing system of the bacteria

text: Vibrio harveyi

text: . The pathway that induces Vibrio harveyi

text: luminescence

text: is controlled by two parallel

text: pathways

text: . The first pathway uses a typical AI-1

text: homoserine lactone

text: signaling molecule. However the bacteria were also found to recognize a second auto inducer AI-2. Scientist also found that V. harveyi luminescence could be induced by 75 other bacterial species AI-2 molecules.This discovery led to the proposal of AI-2 as a universal form of communication between bacteria species. In addition to information about cell densities AI-2 can provide information on the

text: growth phase

text: and prosperity of cells in a population. It has a greater ability to store information than other quorum sensing molecules because its production is tied to cell growth. The production of AI-2 peaks in late log phase for many bacteria. The structure of AI-2 was discovered recently to be a fused 2-member ring with

text: boron

text: bridging the gap between the

text: diester

text: s.

text: Beginning in the 2000s, there was a resurgence in interest in the idea of moving or optimizing the headlight beam in response not only to vehicular steering and suspension dynamics, but also to ambient weather and visibility conditions, vehicle speed, and road curvature and contour. A task force under the EUREKA organisation, composed primarily of European automakers, lighting companies and regulators began working to develop design and performance specifications for what is known as Adaptive Front-Lighting Systems, commonly AFS.Manufacturers such as BMW, Toyota, Škoda and Vauxhall/Opel have released vehicles equipped with AFS since 2003.

text: Beginning in the 2000s, there was a resurgence in interest in the idea of moving or optimizing the headlight beam in response not only to vehicular steering and suspension dynamics, but also to ambient weather and visibility conditions, vehicle speed, and road curvature and contour. A task force under the

text: EUREKA

text: organisation, composed primarily of European automakers, lighting companies and regulators began working to develop design and performance specifications for what is known as Adaptive Front-Lighting Systems, commonly AFS.Manufacturers such as

text: BMW

text: Toyota

text: Škoda

text: and

text: Vauxhall

text: Opel

text: have released vehicles equipped with AFS since 2003.

text: The bioluminescence of O. nidiformis fruit bodies is best seen in low-light conditions when the viewer's eyes have become dark-adapted. The gills are the most luminescent part of the fungus, emitting a greenish light that fades with age. Although the intensity of the luminescence is variable, William Henry Harvey once reported that it was bright enough to read a watch face by. It is not known if the mycelium is also luminescent.

text: The bioluminescence of O. nidiformis fruit bodies is best seen in low-light conditions when the viewer's eyes have become

text: dark-adapted

text: . The gills are the most luminescent part of the fungus, emitting a greenish light that fades with age. Although the intensity of the luminescence is variable,

text: William Henry Harvey

text: once reported that it was bright enough to read a watch face by. It is not known if the

text: mycelium

text: is also luminescent.

text: What archival evidence has so far come to light, together with the visible evidence on the ground, tends towards the agricultural explanation rather than the navigational one, but a final answer depends on the discovery of further evidence. In the meantime the book referenced below contains a number of papers by different writers discussing the various theories, and numerous source references.

text: Chromatin bridges can be viewed utilizing a laboratory technique known as fluorescence microscopy. Fluorescence is the process that involves excitation of a fluorophore (a molecule with the ability to emit fluorescent light in the visible light spectrum) using ultraviolet light. After the fluorophore becomes chemically excited by the presence of UV light, it emits visible light at a specific wavelength, producing different colors. Fluorophores may be added as a molecular tag to different portions of a cell. DAPI is a fluorophore that specifically binds to DNA and fluoresces blue. In addition, immunofluorescence may be used as a laboratory technique to tag cells with specific fluorophores using antibodies, immune proteins created by B lymphocytes. Antibodies are utilized by the immune system in the identification and binding of foreign substances. Tubulin is a monomer of microtubules that compose the cellular cytoskeleton. The antibody anti-tubulin specifically binds to these tubulin monomeric subunits. A fluorophore can be chemically attached to the anti-tubulin antibody, which then fluoresces green. Numerous antibodies may bind to microtubules in order to amplify the fluorescent signal. Fluorescence microscopy allows for the observation of different components of the cell against a dark background for high intensity and specificity.

text: Chromatin bridges can be viewed utilizing a laboratory technique known as

text: fluorescence microscopy

text: . Fluorescence is the process that involves excitation of a

text: fluorophore

text: (a molecule with the ability to emit fluorescent light in the visible light spectrum) using

text: ultraviolet light

text: . After the fluorophore becomes chemically excited by the presence of UV light, it emits visible light at a specific wavelength, producing different colors. Fluorophores may be added as a molecular tag to different portions of a cell.

text: DAPI

text: is a fluorophore that specifically binds to DNA and fluoresces blue. In addition,

text: immunofluorescence

text: may be used as a laboratory technique to tag cells with specific fluorophores using

text: antibodies

text: , immune proteins created by

text: B lymphocytes

text: . Antibodies are utilized by the immune system in the identification and binding of foreign substances.

text: Tubulin

text: is a

text: monomer

text: of

text: microtubules

text: that compose the cellular

text: cytoskeleton

text: . The antibody anti-tubulin specifically binds to these tubulin monomeric subunits. A fluorophore can be chemically attached to the anti-tubulin antibody, which then fluoresces green. Numerous antibodies may bind to microtubules in order to amplify the fluorescent signal. Fluorescence microscopy allows for the observation of different components of the cell against a dark background for high intensity and specificity.

text: Although protection is a primary purpose of glazing, displaying an artwork is the primary purpose of framing it. Therefore, the least visible glazing best displays the artwork behind it. Visible light transmission is the primary measure of glass' invisibility, since the viewer actually sees the light, reflected from the artwork. Light transmission of glass is especially important in art framing, since light passes through the glass twice – once to illuminate the artwork, and then again, reflected from the artwork, as colors - before reaching the viewer.

text: Although protection is a primary purpose of glazing, displaying an artwork is the primary purpose of framing it. Therefore, the least visible glazing best displays the artwork behind it.

text: Visible light

text: transmission is the primary measure of glass' invisibility, since the viewer actually sees the light, reflected from the artwork. Light transmission of glass is especially important in art framing, since light passes through the glass twice – once to illuminate the artwork, and then again, reflected from the artwork, as colors - before reaching the viewer.

text: An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of memory chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power supply has been turned off and back on is called non-volatile.  It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages than those normally used in digital circuits.  Once programmed, an EPROM can be erased by exposing it to strong ultraviolet light source (such as from a mercury-vapor light). EPROMs are easily recognizable by the transparent fused quartz window in the top of the package, through which the silicon chip is visible, and which permits exposure to ultraviolet light during erasing.

text: An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of memory

text: chip

text: that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power supply has been turned off and back on is called

text: non-volatile

text: .  It is an array of

text: floating-gate transistor

text: s individually programmed by an electronic device that supplies higher voltages than those normally used in digital circuits.  Once programmed, an EPROM can be erased by exposing it to strong

text: ultraviolet

text: light source (such as from a mercury-vapor light). EPROMs are easily recognizable by the transparent

text: fused quartz

text: window in the top of the package, through which the

text: silicon

text: chip is visible, and which permits exposure to

text: ultraviolet

text: light during erasing.

text: The first navigation aid on Cleveland Point was a beacon established in 1847, by Francis Edward Bigge, Member of the Legislative Assembly of New South Wales, at his expense, as part of his lobbying of Cleveland as the port for Moreton Bay. In the middle of the 19th century, small coastal steamboats became a main means of transport for farmers in Moreton Bay, specifically in Cleveland, Victoria Point, Redland Bay and along the Logan River and Albert River. Several lights were established around that period to assist navigation in Moreton Bay, notorious for its rocks and moving mudflats and sandbanks. In some places where no official light was established, locals would install their own lights, as was the case in Cleveland Point. In the 1860s the Government of Queensland decided to replace these lights with a permanent light. The first temporary government light was displayed in April 1864. The permanent light was constructed in late 1864 to early 1865. The original light source was a fixed kerosene operated light, visible for . In 1874 a refurbished Chance Brothers Fresnel lens from Comboyuro Point Light on Moreton Island replaced the original lens. The apparatus was upgraded to a more powerful Chance Brothers lens in 1879. Two red sectors, indicating close-by shoals were installed in 1920. In 1934 the lighthouse was converted to electricity and the City Electric Light Company Limited became the responsible operator. The light source was a round concentrated filament lamp.

text: The first navigation aid on Cleveland Point was a beacon established in 1847, by

text: Francis Edward Bigge

text: Member of the Legislative Assembly

text: of

text: New South Wales

text: , at his expense, as part of his lobbying of Cleveland as the port for Moreton Bay. In the middle of the 19th century, small coastal

text: steamboat

text: s became a main means of transport for farmers in Moreton Bay, specifically in Cleveland,

text: Victoria Point

text: Redland Bay

text: and along the

text: Logan River

text: and

text: Albert River

text: . Several lights were established around that period to assist navigation in Moreton Bay, notorious for its rocks and moving

text: mudflat

text: s and

text: sandbank

text: s. In some places where no official light was established, locals would install their own lights, as was the case in Cleveland Point. In the 1860s the

text: Government of Queensland

text: decided to replace these lights with a permanent light. The first temporary government light was displayed in April 1864. The permanent light was constructed in late 1864 to early 1865. The original light source was a fixed

text: kerosene

text: operated light, visible for . In 1874 a refurbished

text: Chance Brothers

text: Fresnel lens

text: from Comboyuro Point Light on

text: Moreton Island

text: replaced the original lens. The apparatus was upgraded to a more powerful Chance Brothers lens in 1879. Two red sectors, indicating close-by

text: shoal

text: s were installed in 1920. In 1934 the lighthouse was converted to electricity and the City Electric Light Company Limited became the responsible operator. The light source was a round concentrated

text: filament lamp

text: Not all wavelengths of light are equally visible, or equally effective at stimulating human vision, due to the spectral sensitivity of the human eye; radiation in the infrared and ultraviolet parts of the spectrum is useless for illumination. The luminous efficacy of a source is the product of how well it converts energy to electromagnetic radiation, and how well the emitted radiation is detected by the human eye.

text: Not all wavelengths of light are equally visible, or equally effective at stimulating human vision, due to the

text: spectral sensitivity

text: of the

text: human eye

text: ; radiation in the

text: infrared

text: and

text: ultraviolet

text: parts of the spectrum is useless for illumination. The luminous efficacy of a source is the product of how well it converts energy to electromagnetic radiation, and how well the emitted radiation is detected by the human eye.

text: Cathodoluminescence is an optical and electromagnetic phenomenon in which electrons impacting on a luminescent material such as a phosphor, cause the emission of photons which may have wavelengths in the visible spectrum. A familiar example is the generation of light by an electron beam scanning the phosphor-coated inner surface of the screen of a television that uses a cathode ray tube. Cathodoluminescence is the inverse of the photoelectric effect, in which electron emission is induced by irradiation with photons.

text: Cathodoluminescence is an

text: optical

text: and

text: electromagnetic phenomenon

text: in which electrons impacting on a

text: luminescent

text: material such as a

text: phosphor

text: , cause the emission of

text: photons

text: which may have wavelengths in the

text: visible spectrum

text: . A familiar example is the generation of light by an electron beam scanning the phosphor-coated inner surface of the screen of a

text: television

text: that uses a

text: cathode ray tube

text: . Cathodoluminescence is the inverse of the

text: photoelectric effect

text: , in which electron emission is induced by irradiation with photons.

text: Although FFP designs are not susceptible to magnification-induced errors, they have their own disadvantages. It's challenging to design a reticle that is visible through the entire range of magnification: a reticle that looks fine and crisp at 24x magnification may be very difficult to see at 6x . On the other hand, a reticle that's easy to see at 6x may be thick enough at 24x to make precision shots difficult. Shooting in low light conditions also tends to require either illumination or a bold reticle, along with lower magnification to maximize light gathering. In practice, these issues tend to significantly reduce the available magnification range on FFP scopes compared to SFP, and FFP scopes are much more expensive compared to SFP models of similar quality. Most high-end optics manufacturers leave the choice between a FFP or SFP mounted reticle to the customer or have scope product models with both setups.

text: The image on the right was rendered using a radiosity algorithm. There is only one source of light: an image of the sky placed outside the window. The difference is marked. The room glows with light. Soft shadows are visible on the floor, and subtle lighting effects are noticeable around the room. Furthermore, the red color from the carpet has bled onto the grey walls, giving them a slightly warm appearance. None of these effects were specifically chosen or designed by the artist.

text: Flare is particularly caused by very bright light sources. Most commonly, this occurs when shooting into the sun (when the sun is in frame or the lens is pointed in the direction of the sun), and is reduced by using a lens hood or other shade.  For good-quality optical systems, and for most images (which do not have a bright light shining into the lens), flare is a secondary effect that is widely distributed across the image and thus not visible, although it does reduce contrast.

text: Flare is particularly caused by very bright light sources. Most commonly, this occurs when shooting into the sun (when the sun is in frame or the lens is pointed in the direction of the sun), and is reduced by using a

text: lens hood

text: or other shade.  For good-quality optical systems, and for most images (which do not have a bright light shining into the lens), flare is a secondary effect that is widely distributed across the image and thus not visible, although it does reduce contrast.

text: II.  Second, there is no distinction to be made between illumination emitted from a light source and illumination reflected from a surface.

text: A tiny sun and moon orbit the Great A'Tuin, both about 1 mile in diameter when described at the start of the series, but the description of their diameter is increased to at least 80 miles later in the chronicles. The moon is slightly closer to the Disc than the sun, and is covered, on one half, with silvery glowing plants, which feed the lunar dragons. The other half is burnt black by the sun. The moon rotates, and completes a full revolution in about a month; the full moon occurs when the luminescent side is completely visible from the Disc, the new moon when the dark side is shown. The sun's orbit is so complex that one of the elephants has to cock its leg to allow the sun to continue on its orbit.

text: A tiny

text: sun

text: and

text: moon

text: orbit the Great A'Tuin, both about 1 mile in diameter when described at the start of the series, but the description of their diameter is increased to at least 80 miles later in the chronicles. The moon is slightly closer to the Disc than the sun, and is covered, on one half, with silvery glowing plants, which feed the

text: lunar dragons

text: . The other half is burnt black by the sun. The moon rotates, and completes a full revolution in about a month; the full moon occurs when the luminescent side is completely visible from the Disc, the new moon when the dark side is shown. The sun's orbit is so complex that one of the elephants has to cock its leg to allow the sun to continue on its orbit.

text: Light sources used include infrared LEDs, visible LEDs, miniature light-bulbs and laser diodes.

text: Light sources used include infrared

text: LEDs

text: , visible LEDs, miniature light-bulbs and

text: laser diode

text: s.

text: Following the retirement in 2007 from Hannover professorship, Werner Urland resumed the scientific activity as guest senior researcher in the group of Professor Claude Daul at University of Fribourg (Switzerland), where he proposed a topic related to the so-called "Warm-White Light", namely the improvement of blue-type Light-emitting diodes (LEDs) towards the better resemblance to the sunlight spectrum by coating with appropriate phosphors based on lanthanide doped materials.  The topic represents a hot relevance in the context of the trends of eliminating traditional incandescent light bulbs, for the sake of energy saving new technologies . This technological challenge is underlined by the award of the 2014 Nobel Prize in Physics "for the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources" to Shuji Nakamura, Isamu Akasaki and Hiroshi Amano and by the declaration of 2015 as the The 'International Year of Light and Light-based Technologies, (IYL 2015). Hybridizing Werner's Urland expertise in experimental and theoretical aspects of rare earth materials with a computation and analysis methodology due to C. Daul and M. Atanasov, altogether with methodological knowledge of external collaborators of the group, a series of works was produced, dealing with the analysis and prediction form first principles of the key factors in the luminescence of relevant lanthanide ions in various environments.The modelling is based on a set of algorithmic steps abbreviated as LFDFT,  consisting in non-routine calculations in the frame of Density Functional Theory (DFT) followed by the analysis in the frame of Ligand Field Theory. The issue of first principles calculations on rare-earth systems is non-trivial, because of special features of the f-shell, such as the shielded and weakly interacting nature, that poses technical and conceptual difficulties, in relation to modern methods of quantum chemistry. The specific problem of the modelling the luminescence of rare-earth systems called the need of extending the ligand field phenomenology, from its one-shell status (dedicated to d or f electrons) to a two-shell Hamiltonian (quantum mechanics), comprising simultaneously the d and f shells, because the involved optical transitions  have inter-shell nature. Also recently, Werner Urland, entered the terrain of actinide chemistry, explaining intriguing magnetic behaviour due strong ligand field on uranium(IV) ions in thiophosphates and silicates.The whole deal underlines the validity and renewed value of Werner Urland's early ideas about the theoretical and practical aspects emerging from the chemistry and physics of f-elements.

text: Following the retirement in 2007 from Hannover professorship, Werner Urland resumed the scientific activity as guest senior researcher in the group of Professor Claude Daul at

text: University of Fribourg

text: Switzerland

text: ), where he proposed a topic related to the so-called "Warm-White Light", namely the improvement of blue-type

text: Light-emitting diode

text: s (LEDs) towards the better resemblance to the sunlight spectrum by coating with appropriate

text: phosphor

text: s based on lanthanide doped materials.  The topic represents a hot relevance in the context of the trends of eliminating traditional incandescent light bulbs, for the sake of energy saving new technologies . This technological challenge is underlined by the award of the 2014

text: Nobel Prize in Physics

text: "for the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources" to

text: Shuji Nakamura

text: Isamu Akasaki

text: and

text: Hiroshi Amano

text: and by the declaration of 2015 as the

text: The 'International Year of Light

text: and Light-based Technologies, (IYL 2015). Hybridizing Werner's Urland expertise in experimental and theoretical aspects of rare earth materials with a computation and analysis methodology due to C. Daul and M. Atanasov, altogether with methodological knowledge of external collaborators of the group, a series of works was produced, dealing with the analysis and prediction form first principles of the key factors in the

text: luminescence

text: of relevant lanthanide ions in various environments.The modelling is based on a set of algorithmic steps abbreviated as LFDFT,  consisting in non-routine calculations in the frame of

text: Density Functional Theory

text: (DFT) followed by the analysis in the frame of

text: Ligand Field Theory

text: . The issue of first principles calculations on rare-earth systems is non-trivial, because of special features of the f-shell, such as the shielded and weakly interacting nature, that poses technical and conceptual difficulties, in relation to modern methods of quantum chemistry. The specific problem of the modelling the

text: luminescence

text: of rare-earth systems called the need of extending the ligand field phenomenology, from its one-shell status (dedicated to d or f electrons) to a two-shell

text: Hamiltonian (quantum mechanics)

text: , comprising simultaneously the d and f shells, because the involved optical transitions  have inter-shell nature. Also recently, Werner Urland, entered the terrain of actinide chemistry, explaining intriguing magnetic behaviour due strong ligand field on uranium(IV) ions in thiophosphates and silicates.The whole deal underlines the validity and renewed value of Werner Urland's early ideas about the theoretical and practical aspects emerging from the chemistry and physics of f-elements.

text: The primary limitation of critical illumination is the formation of an image of the light source in the specimen image plane. Köhler illumination addresses this by ensuring the image of the light source is perfectly defocused in the sample plane and its conjugate image planes. In a ray diagram of the illumination light path this can be seen as the image-forming rays passing parallel through the sample.

text: The primary limitation of critical illumination is the formation of an image of the light source in the specimen image plane. Köhler illumination addresses this by ensuring the image of the light source is perfectly

text: defocus

text: ed in the sample plane and its

text: conjugate image planes

text: . In a ray diagram of the illumination light path this can be seen as the image-forming rays passing parallel through the sample.

text: Pendry also suggested that a lens having only one negative parameter would form an approximate superlens, provided that the distances involved are also very small and provided that the source polarization is appropriate. For visible light this is a useful substitute, since engineering metamaterials with a negative permeability at the frequency of visible light is difficult. Metals are then a good alternative as they have negative permittivity (but not negative permeability). Pendry suggested using silver due to its relatively low loss at the predicted wavelength of operation (356 nm). In 2003 Pendry's theory was first experimentally demonstrated by Parimi et al. at RF/microwave frequencies. In 2005, two independent groups verified Pendry's lens at UV range, both using thin layers of silver illuminated with UV light to produce "photographs" of objects smaller than the wavelength. Negative refraction of visible light was experimentally verified in an yttrium orthovanadate (YVO) bicrystal in 2003.

text: Pendry also suggested that a lens having only one negative parameter would form an approximate superlens, provided that the distances involved are also very small and provided that the source polarization is appropriate. For visible light this is a useful substitute, since engineering metamaterials with a negative permeability at the frequency of visible light is difficult. Metals are then a good alternative as they have negative permittivity (but not negative permeability). Pendry suggested using

text: silver

text: due to its relatively low loss at the predicted wavelength of operation (356 nm). In 2003 Pendry's theory was first experimentally demonstrated by Parimi et al. at RF/microwave frequencies. In 2005, two independent groups verified Pendry's lens at UV range, both using thin layers of silver illuminated with UV light to produce "photographs" of objects smaller than the wavelength. Negative refraction of visible light was experimentally verified in an

text: yttrium orthovanadate

text: (YVO) bicrystal in 2003.

text: In 2013, researchers at Michigan State University demonstrated the first visibly transparent luminescent solar concentrators.  These devices were composed of phosphorescent metal halide nanocluster (or Quantum Dot) blends that exhibit massive Stokes shift (or downconversion) and which selectively absorb ultraviolet and emit near-infrared light, allowing for selective harvesting, improved reabsorption efficiency, and non-tinted transparency in the visible spectrum.The following year, these researchers demonstrated near-infrared harvesting visibly transparent luminescent solar concentrators by utilizing luminescent organic salt derivatives. These devices exhibit a clear visible transparency similar to that of glass and a power conversion efficiency close to 0.5%. In this configuration efficiencies of over 10% are possible due to the large fraction of photon flux in the near-infrared spectrum.

text: In 2013, researchers at Michigan State University demonstrated the first visibly transparent luminescent solar concentrators.  These devices were composed of phosphorescent metal halide nanocluster (or

text: Quantum Dot

text: ) blends that exhibit massive Stokes shift (or downconversion) and which selectively absorb ultraviolet and emit near-infrared light, allowing for selective harvesting, improved reabsorption efficiency, and non-tinted transparency in the visible spectrum.The following year, these researchers demonstrated near-infrared harvesting visibly transparent luminescent solar concentrators by utilizing luminescent organic salt derivatives. These devices exhibit a clear visible transparency similar to that of glass and a power conversion efficiency close to 0.5%. In this configuration efficiencies of over 10% are possible due to the large fraction of photon flux in the near-infrared spectrum.

text: Pliny spoke of luminescence in the mouths of people who ate Pholas, the rock-boring shell-fish, and of such importance is this phenomenon that it is even said to have gained the first king of Scotland his throne.

text: Pliny

text: spoke of luminescence in the mouths of people who ate Pholas, the rock-boring shell-fish, and of such importance is this phenomenon that it is even said to have gained the first king of Scotland his throne.

text: While exit signs were more visible due to large letters, even a 60-watt bulb shown through a plastic or glass cover (see image), could appear somewhat dim under certain conditions.  With the development of fluorescent lamp and light-emitting diode technology, exit signs could be made even brighter to show up in the limited visibility of a fire situation, or use less electricity.  LED signs combine a large number of bright light-emitting diodes to illuminate the sign from inside.  Fluorescent lamps work in the same way as incandescent bulbs, back-lighting both sides of an exit fixture from within. Because an exit sign is constantly lit, fluorescent bulbs need to be changed more often than LEDs, although the almost nonexistent on/off cycles extend the life of fluorescent lamps significantly.  Generally, LEDs have a very long life, and may last for 10 years or more of continuous use, although the brightness may diminish. . Incandescent bulbs are still in use, because they are cheap and common, even though they use more electricity and require more or less frequent replacement. Bulbs lit 24/7 will have a greatly extended lifespan.

text: While exit signs were more visible due to large letters, even a 60-watt bulb shown through a plastic or glass cover (see image), could appear somewhat dim under certain conditions.  With the development of

text: fluorescent lamp

text: and

text: light-emitting diode

text: technology, exit signs could be made even brighter to show up in the limited visibility of a fire situation, or use less electricity.  LED signs combine a large number of bright light-emitting diodes to illuminate the sign from inside.  Fluorescent lamps work in the same way as incandescent bulbs, back-lighting both sides of an exit fixture from within. Because an exit sign is constantly lit, fluorescent bulbs need to be changed more often than LEDs, although the almost nonexistent on/off cycles extend the life of fluorescent lamps significantly.  Generally, LEDs have a very long life, and may last for 10 years or more of continuous use, although the brightness may diminish. . Incandescent bulbs are still in use, because they are cheap and common, even though they use more electricity and require more or less frequent replacement. Bulbs lit 24/7 will have a greatly extended lifespan.

text: Altering the condenser diaphragm allows the amount of light entering the sample to be freely adjusted without altering the wavelengths of light present, in contrast to reducing power to the light source with critical illumination (which changes the color temperature of the lamp). However, this adjustment is always coupled to an alteration of the numerical aperture of the system, as stated above, and so adjustment of the illumination source intensity by other means is still necessary.

text: Altering the condenser diaphragm allows the amount of light entering the sample to be freely adjusted without altering the wavelengths of light present, in contrast to reducing power to the light source with critical illumination (which changes the

text: color temperature

text: of the lamp). However, this adjustment is always coupled to an alteration of the numerical aperture of the system, as stated above, and so adjustment of the illumination source intensity by other means is still necessary.

text: Each gas, depending on its atomic structure emits certain wavelengths, its emission spectrum, which determines the color of the light from the lamp. As a way of evaluating the ability of a light source to reproduce the colors of various objects being lit by the source, the International Commission on Illumination (CIE) introduced the color rendering index (CRI). Some gas-discharge lamps have a relatively low CRI, which means colors they illuminate appear substantially different from how they do under sunlight or other high-CRI illumination.

text: Each gas, depending on its atomic structure emits certain wavelengths, its

text: emission spectrum

text: , which determines the color of the light from the lamp. As a way of evaluating the ability of a light source to reproduce the colors of various objects being lit by the source, the

text: International Commission on Illumination

text: (CIE) introduced the

text: color rendering index

text: (CRI). Some gas-discharge lamps have a relatively low CRI, which means colors they illuminate appear substantially different from how they do under sunlight or other high-CRI illumination.

text: In 1952 Brookhaven began using its first particle accelerator, the Cosmotron. At the time the Cosmotron was the world's highest energy accelerator, being the first to impart more than 1 GeV of energy to a particle. The Cosmotron was retired in 1966, after it was superseded in 1960 by the new Alternating Gradient Synchrotron (AGS). The AGS was used in research that resulted in 3 Nobel prizes, including the discovery of the muon neutrino, the charm quark, and CP violation. The National Synchrotron Light Source operated from 1982-2014 and was involved with two Nobel Prize-winning discoveries. It has since been replaced by the National Synchrotron Light Source II. The Relativistic Heavy Ion Collider (RHIC) has been operational since 2000. One of the world's only two operating heavy-ion colliders, RHIC is as of 2010 the second-highest-energy collider after the Large Hadron Collider. RHIC is housed in a tunnel 2.4 miles (3.9 km) long and is visible from space.

text: In 1952 Brookhaven began using its first

text: particle accelerator

text: , the

text: Cosmotron

text: . At the time the Cosmotron was the world's highest energy accelerator, being the first to impart more than 1

text: GeV

text: of energy to a particle. The Cosmotron was retired in 1966, after it was superseded in 1960 by the new

text: Alternating Gradient Synchrotron

text: (AGS). The AGS was used in research that resulted in 3

text: Nobel prizes

text: , including the discovery of the

text: muon neutrino

text: , the

text: charm quark

text: , and

text: CP violation

text: . The

text: National Synchrotron Light Source

text: operated from 1982-2014 and was involved with two Nobel Prize-winning discoveries. It has since been replaced by the

text: National Synchrotron Light Source II

text: . The

text: Relativistic Heavy Ion Collider

text: (RHIC) has been operational since 2000. One of the world's only two operating heavy-ion colliders, RHIC is as of 2010 the second-highest-energy collider after the

text: Large Hadron Collider

text: . RHIC is housed in a tunnel 2.4 miles (3.9 km) long and is visible from space.

text: A lightcast is a functional analysis and mapping of the illumination produced by a light source. It is used to map the physical characteristics of light emission for use in functional systems. A lightcast includes the entire zone of illumination while a raycast measures lighting of a single point in space near the light source.

text: A lightcast is a

text: functional analysis

text: and mapping of the

text: illumination

text: produced by a

text: light source

text: . It is used to map the physical characteristics of light emission for use in functional systems. A lightcast includes the entire zone of illumination while a

text: raycast

text: measures lighting of a single point in space near the light source.

text: A video camera can be seen as an approximation of a pinhole camera, which means that each point in the image is illuminated by some (normally one) point in the scene in front of the camera, usually by means of light that the scene point reflects from a light source.  Each visible point in the scene is projected along a straight line that passes through the camera aperture and intersects the image plane.  This means that at a specific point in time, each point in the image refers to a specific point in the scene.  This scene point has a position relative to the camera, and if this relative position changes, it corresponds to a relative motion in 3D.  It is a relative motion since it does not matter if it is the scene point, or the camera, or both, that are moving.  It is only when there is a change in the relative position that the camera is able to detect that some motion has happened.  By projecting the relative 3D motion of all visible points back into the image, the result is the motion field, describing the apparent motion of each image point in terms of a magnitude and direction of velocity of that point in the image plane.  A consequence of this observation is that if the relative 3D motion of some scene points are along their projection lines, the corresponding apparent motion is zero.

text: A video camera can be seen as an approximation of a

text: pinhole camera

text: , which means that each point in the image is illuminated by some (normally one) point in the scene in front of the camera, usually by means of light that the scene point reflects from a light source.  Each visible point in the scene is projected along a straight line that passes through the camera aperture and intersects the image plane.  This means that at a specific point in time, each point in the image refers to a specific point in the scene.  This scene point has a position relative to the camera, and if this relative position changes, it corresponds to a relative motion in 3D.  It is a relative motion since it does not matter if it is the scene point, or the camera, or both, that are moving.  It is only when there is a change in the relative position that the camera is able to detect that some motion has happened.  By projecting the relative 3D motion of all visible points back into the image, the result is the

text: motion field

text: , describing the apparent motion of each image point in terms of a magnitude and direction of velocity of that point in the image plane.  A consequence of this observation is that if the relative 3D motion of some scene points are along their projection lines, the corresponding apparent motion is zero.

text: Of the power consumed by typical incandescent light bulbs, 95% or more is converted into heat rather than visible light.  Other electrical light sources are more effective.

text: Single photon sources are novel types of light sources distinct from coherent light sources (lasers) and thermal light sources (such as incandescent light bulbs and mercury-vapor lamps) that emit light as single particles or photons.

text: Incandescent versus Compact Fluorescent-Incandescents pass electricity through a small filament (wire) causing it to glow hot and produce lumens (light).  Up to 90 percent of the energy used in this process is for heat, not light, production.  This wasted energy is far offset by Compact Fluorescents as they process lumens through a gas charged tube; electricity passes through the tube to create a chemical reaction that yields light.  This cooler source focuses almost all its energy on light production, itself.

text: The finished plate was illuminated from the front at a nearly perpendicular angle, using daylight or another source of white light containing the full range of wavelengths in the visible spectrum. At each point on the plate, light of approximately the same wavelength as the light which had generated the laminae was strongly reflected back toward the viewer. Light of other wavelengths which was not absorbed or scattered by the silver grains simply passed through the emulsion, usually to be absorbed by a black anti-reflection coating applied to the back of the plate after it had been developed. The wavelengths, and therefore the colours, of the light which had formed the original image were thus reconstituted and a full-colour image was seen.

text: The finished plate was illuminated from the front at a nearly

text: perpendicular

text: angle, using daylight or another source of white light containing the full range of wavelengths in the

text: visible spectrum

text: . At each point on the plate, light of approximately the same wavelength as the light which had generated the laminae was strongly reflected back toward the viewer. Light of other wavelengths which was not absorbed or scattered by the silver grains simply passed through the emulsion, usually to be absorbed by a black anti-reflection coating applied to the back of the plate after it had been developed. The wavelengths, and therefore the colours, of the light which had formed the original image were thus reconstituted and a full-colour image was seen.

text: By comparison, incandescent lamps have a brief warm-up when energized, followed by a cool-down period when power is removed. These delays result in smearing and blurring of detail of objects partially illuminated during the warm-up and cool-down periods. For most applications, incandescent lamps are too slow for clear stroboscopic effects. Yet when operated from an AC source they are mostly fast enough to cause audible hum (at double mains frequency) on optical audio playback such as on film projection.

text: By comparison,

text: incandescent lamp

text: s have a brief warm-up when energized, followed by a cool-down period when power is removed. These delays result in smearing and blurring of detail of objects partially illuminated during the warm-up and cool-down periods. For most applications, incandescent lamps are too slow for clear stroboscopic effects. Yet when operated from an AC source they are mostly fast enough to cause audible hum (at double mains frequency) on

text: optical audio playback

text: such as on film projection.

text: Very low voltages are inefficient since the lead wires would conduct too much heat away from the filament, so the practical lower limit for incandescent lamps is 1.5 volts. Very long filaments for high voltages are fragile, and lamp bases become more difficult to insulate, so lamps for illumination are not made with rated voltages over 300 volts. Some infrared heating elements are made for higher voltages, but these use tubular bulbs with widely separated terminals.

text: Optical fingerprint imaging involves capturing a digital image of the print using visible light.  This type of sensor is, in essence, a specialized digital camera.  The top layer of the sensor, where the finger is placed, is known as the touch surface.  Beneath this layer is a light-emitting phosphor layer which illuminates the surface of the finger.  The light reflected from the finger passes through the phosphor layer to an array of solid state pixels (a charge-coupled device) which captures a visual image of the fingerprint.  A scratched or dirty touch surface can cause a bad image of the fingerprint.  A disadvantage of this type of sensor is the fact that the imaging capabilities are affected by the quality of skin on the finger.  For instance, a dirty or marked finger is difficult to image properly.  Also, it is possible for an individual to erode the outer layer of skin on the fingertips to the point where the fingerprint is no longer visible. It can also be easily fooled by an image of a fingerprint if not coupled with a "live finger" detector. However, unlike capacitive sensors, this sensor technology is not susceptible to electrostatic discharge damage.

text: Optical fingerprint imaging involves capturing a digital image of the print using

text: visible light

text: .  This type of sensor is, in essence, a specialized

text: digital camera

text: .  The top layer of the sensor, where the finger is placed, is known as the touch surface.  Beneath this layer is a light-emitting phosphor layer which illuminates the surface of the finger.  The light reflected from the finger passes through the phosphor layer to an array of

text: solid state

text: pixels (a

text: charge-coupled device

text: ) which captures a visual image of the fingerprint.  A scratched or dirty touch surface can cause a bad image of the fingerprint.  A disadvantage of this type of sensor is the fact that the imaging capabilities are affected by the quality of skin on the finger.  For instance, a dirty or marked finger is difficult to image properly.  Also, it is possible for an individual to erode the outer layer of skin on the fingertips to the point where the fingerprint is no longer visible. It can also be easily fooled by an image of a fingerprint if not coupled with a "live finger" detector. However, unlike capacitive sensors, this sensor technology is not susceptible to electrostatic discharge damage.

text: Dimmers are devices used to lower the brightness of a light.  By changing the voltage waveform applied to the lamp, it is possible to lower the intensity of the light output. Although variable-voltage devices are used for various purposes, the term dimmer is generally reserved for those intended to control light output from resistive incandescent, halogen, and (more recently) compact fluorescent lights (CFLs) and light-emitting diodes (LEDs).  More specialized  equipment is needed to dim fluorescent, mercury vapor, solid state and other arc lighting.

text: Dimmers are devices used to lower the brightness of a

text: light

text: .  By changing the voltage waveform applied to the lamp, it is possible to lower the intensity of the light output. Although variable-voltage devices are used for various purposes, the term dimmer is generally reserved for those intended to control light output from

text: resistive

text: incandescent

text: halogen

text: , and (more recently)

text: compact fluorescent light

text: s (CFLs) and

text: light-emitting diode

text: s (LEDs).  More specialized  equipment is needed to dim

text: fluorescent

text: mercury vapor

text: solid state

text: and other

text: arc

text: lighting.

text: Light meters or light detectors are also used in illumination. Their purpose is to measure the illumination level in the interior and to switch off or reduce the output level of luminaires. This can greatly reduce the energy burden of the building by significantly increasing the efficiency of its lighting system. It is therefore recommended to use light meters in lighting systems, especially in rooms where one cannot expect users to pay attention to manually switching off the lights. Examples include hallways, stairs, and big halls.

text: Light meters or light detectors are also used in

text: illumination

text: . Their purpose is to measure the illumination level in the interior and to switch off or reduce the output level of

text: luminaire

text: s. This can greatly reduce the energy burden of the building by significantly increasing the efficiency of its lighting system. It is therefore recommended to use light meters in lighting systems, especially in rooms where one cannot expect users to pay attention to manually switching off the lights. Examples include hallways, stairs, and big halls.

text: A 23 W spiral compact fluorescent lamp emits about 1,400–1,600 lm. Many compact fluorescent lamps and other alternative light sources are labeled as being equivalent to an incandescent bulb with a specific wattage. Below is a table that shows typical luminous flux for common incandescent bulbs and their equivalents.

text: A 23 W spiral

text: compact fluorescent lamp

text: emits about 1,400–1,600 lm. Many compact fluorescent lamps and other alternative light sources are labeled as being equivalent to an incandescent bulb with a specific wattage. Below is a table that shows typical luminous flux for common incandescent bulbs and their equivalents.

text: Spectroscopic methods for observing the absorption of electromagnetic radiation in the visible spectrum were known as early as the 1860s.Scientists had observed that light traveling through a medium would be absorbed at different wavelengths, depending on the matter-composition of the medium involved.  A white light source would emit light at multiple wavelengths over a range of frequencies.  A prism could be used to separate a light source into specific wavelengths. Shining the light through a sample of a material would cause some wavelengths of light to be absorbed, while others would be unaffected and continue to be transmitted.  Wavelengths in the resulting absorption spectrum would differ depending upon the atomic and molecular  composition if the material involved.

text: Spectroscopic methods for observing the

text: absorption

text: of

text: electromagnetic radiation

text: in the

text: visible spectrum

text: were known as early as the 1860s.Scientists had observed that light traveling through a

text: medium

text: would be absorbed at different wavelengths, depending on the matter-composition of the medium involved.  A white light source would emit light at multiple wavelengths over a range of frequencies.  A prism could be used to separate a light source into specific wavelengths. Shining the light through a sample of a material would cause some wavelengths of light to be absorbed, while others would be unaffected and continue to be transmitted.  Wavelengths in the resulting

text: absorption spectrum

text: would differ depending upon the

text: atom

text: ic and

text: molecular

text: composition if the material involved.

text: Also known as plane reflectors, "flats" or bounce boards, this kind of reflector is located independent of a light source; the light is reflected off its surface, either to achieve a broader light source, or control shadows and highlights, or both. This kind of reflector generally has a very low reflectivity factor that varies widely according to surface texture and colour. As a result, it is most commonly used to control contrast in both artificial and natural lighting, in place of a fill light or "kick" light. In this case, light "spilling" from the main ambient or key light illuminating a scene is reflected back into the scene with a varying degrees of precision and intensity, according to the chosen reflective surface and its position relative to the scene.

text: Also known as

text: plane

text: reflectors, "flats" or bounce boards, this kind of reflector is located independent of a light source; the light is reflected off its surface, either to achieve a broader light source, or control shadows and highlights, or both. This kind of reflector generally has a very low reflectivity factor that varies widely according to surface texture and colour. As a result, it is most commonly used to control

text: contrast

text: in both artificial and natural

text: lighting

text: , in place of a

text: fill light

text: or "kick" light. In this case, light "spilling" from the main ambient or key light illuminating a scene is reflected back into the scene with a varying degrees of precision and intensity, according to the chosen reflective surface and its position relative to the scene.

text: Emergency lighting may be fitted to several places on a vehicle, depending on the degree of conspicuity required.  Beacons and lightbars are often mounted on the roof for high visibility, while other lights may be mounted on the body, in the grill, or in the interior of the vehicle.

text: The trivalent dysprosium ion (Dy) has been studied due its downshifting luminescence properties. Dy-doped yttrium aluminium garnet (YAG:Dy) excited in the ultraviolet region of the electromagnetic spectrum results in the emission of photons of longer wavelenght in the visible region. This idea has been in the basis of the new generation of UV-pumped white light emitting diodes.

text: Stanford University Computer Graphics Laboratory has developed a light field microscope using a microlens array similar to the one used in the light field camera developed by the lab. The prototype is built around a Nikon Eclipse transmitted light microscope/wide-field fluorescence microscope and standard CCD cameras. Light field capturing ability is obtained by a module containing a microlens array and other optical components placed in the light path between the objective lens and camera, with the final multifocused image rendered using deconvolution. A later version of the prototype added a light field illumination system consisting of a video projector (allowing computational control of illumination) and a second microlens array in the illumination light path of the microscope. The addition of a light field illumination system both allowed for additional types of illumination (such as oblique illumination and quasi-dark-field) and correction for optical aberrations.

text: Stanford University Computer Graphics Laboratory has developed a light field microscope using a microlens array similar to the one used in the light field camera developed by the lab. The prototype is built around a

text: Nikon

text: Eclipse

text: transmitted light microscope

text: /wide-field

text: fluorescence microscope

text: and standard

text: CCD camera

text: s. Light field capturing ability is obtained by a module containing a microlens array and other optical components placed in the light path between the

text: objective lens

text: and camera, with the final multifocused image rendered using

text: deconvolution

text: . A later version of the prototype added a light field illumination system consisting of a video projector (allowing computational control of illumination) and a second microlens array in the illumination light path of the microscope. The addition of a light field illumination system both allowed for additional types of illumination (such as

text: oblique illumination

text: and quasi-

text: dark-field

text: ) and correction for

text: optical aberrations

text: As part of its investigation, the conducted a flight around the airport, to evaluate the lighting and visibility of the runways and taxiways.  With the lighting of runway 29 and the taxiway set to the same brightness levels used during the incident, the NTSB noted that the lights for taxiway Z appeared slightly brighter than the lights for runway 29. However, during testing the difference in lighting color (green centerline lights used on Z to indicate a taxiway, white centerline lights used on 29 to indicate a runway) was clearly visible to planes on approach.

text: Many depictions reduced other light sources in the scene to emphasize this effect, and the Nativity remained very commonly treated with chiaroscuro through to the Baroque. Here the sources of light are the infant Jesus himself, in accordance with Bridget's vision, who is the sole source of illumination for the main scene inside the stable, the shepherds' fire on the hill behind, and the angel who appears to them.  In fact this effect now goes beyond what was intended by the artist, as the painting was damaged in a fire in 1904, when it was in a private collection in Berlin. The different shades of blue given the upper and lower parts of the Virgin's clothing and the sky outside now appear as murky dark browns or blacks, and the painting is generally darker. The painting had been cut down by 1901.  There is a copy of the painting in the Diocesan Museum in Barcelona, which suggests that the original size was about 45 × 31 cm.  In this the rays emanating from the Christ-Child are more evident, and the animals behind less so.

text: Many depictions reduced other light sources in the scene to emphasize this effect, and the Nativity remained very commonly treated with

text: chiaroscuro

text: through to the

text: Baroque

text: . Here the sources of light are the infant Jesus himself, in accordance with Bridget's vision, who is the sole source of illumination for the main scene inside the stable, the shepherds' fire on the hill behind, and the angel who appears to them.  In fact this effect now goes beyond what was intended by the artist, as the painting was damaged in a fire in 1904, when it was in a private collection in

text: Berlin

text: . The different shades of blue given the upper and lower parts of the Virgin's clothing and the sky outside now appear as murky dark browns or blacks, and the painting is generally darker. The painting had been cut down by 1901.  There is a copy of the painting in the Diocesan Museum in

text: Barcelona

text: , which suggests that the original size was about 45 × 31 cm.  In this the rays emanating from the Christ-Child are more evident, and the animals behind less so.

text: Following the first step, Khatami tries to reformulate the human subject as absolute. He reconsiders here the illuminative tradition of Persian thought a notion of man who is both more than the world and less than the world. As for the former, man, descending from God, is a comprehensive totality as macrocosm within which and through which the world is created; while as for the latter, he, ascending to God, is a singular individual as microcosm shattered and fallen down to the earth, but still has the same colour of the divine essence within him. Khatami highlights the former aspect of this notion which is the source of the latter, and, at the same time, sheds light on the "concealed" essence of human being which is "forgotten" in modern subjectivism. This notion of man constitutes his essence as the integration of the divine inward as well as outward names. Thus, the illuminative man is homocosm of the divine and the worldly realities. He was created as God's vicegerent while the entire world is a particularization of what exists in him. The world was thus created through man and for man, even though in the visible world man appeared the last. The illuminative man, in this capacity, can like Him create by uttering the command "be", is keen on exhibiting his ability to control nature, and above all an absolute subject who comprehends all creation and, by means of that comprehension, comes to dominate over the world and name that which it comprehends. He is Absolute in the sense of  God's vicegerent: The only Created Creator.

text: Following the first step, Khatami tries to reformulate the human subject as absolute. He reconsiders here the illuminative tradition of

text: Persian thought

text: MTA has embarked on various measures to increase visibility of Orange Line Metroliners, including installing white LED strobes on each side of the vehicle to make them appear as if an emergency vehicle was crossing the red-lighted intersections. Drivers' tactics include slowing to approximately  at intersections with poor cross-traffic visibility or blind spots. In addition, the police department heavily patrols the route, with officers in marked cruisers and motorcycles distributing red-light citations.

text: The Kruithof curve is used as a guide to design artificial lighting for working and living spaces, with the general suggestion to use sources with low correlated color temperatures at low illuminances. This is why, for example, fluorescent lamps (in the range of 3000 K to 6000 K) are often run at high illuminances, above 500 lux. Fluorescent lights can be considered as preferred light sources in workspaces so that employees are comfortable and able to focus their efforts on work rather than feeling uncomfortable working under illumination from displeasing light sources. In homes, light sources with less illuminance and lower color temperatures are considered more pleasing and relaxing.

text: The Kruithof curve is used as a guide to design artificial lighting for

text: working

text: and

text: living

text: spaces, with the general suggestion to use sources with low correlated color temperatures at low illuminances. This is why, for example, fluorescent lamps (in the range of 3000 K to 6000 K) are often run at high illuminances, above 500 lux. Fluorescent lights can be considered as preferred light sources in workspaces so that employees are comfortable and able to focus their efforts on work rather than feeling uncomfortable working under illumination from displeasing light sources. In homes, light sources with less illuminance and lower color temperatures are considered more pleasing and relaxing.

text: Hope shows its central character alone, with no other human figures visible and without her traditional fellow virtues, Love (also known as Charity) and Faith. She is dressed in classical costume, based on the Elgin Marbles; Nicholas Tromans of Kingston University speculated that her Greek style of clothing was intentionally chosen to evoke the ambivalent nature of hope in Greek mythology over the certainties of Christian tradition. Her pose is based on that of Michelangelo's Night, in an intentionally strained position. She sits on a small, imperfect orange globe with wisps of cloud around its circumference, against an almost blank mottled blue background. The figure is illuminated faintly from behind, as if by starlight, and also directly from the front as if the observer is the source of light. Watts's use of light and tone avoids the clear definition of shapes, creating a shimmering and dissolving effect more typically associated with pastel work than with oil painting.

text: Hope shows its central character alone, with no other human figures visible and without her traditional fellow virtues, Love (also known as Charity) and Faith. She is dressed in

text: classical

text: costume, based on the

text: Elgin Marbles

text: ; Nicholas Tromans of

text: Kingston University

text: speculated that her Greek style of clothing was intentionally chosen to evoke the ambivalent nature of hope in Greek mythology over the certainties of Christian tradition. Her pose is based on that of

text: Michelangelo

text: 's

text: Night

text: , in an intentionally strained position. She sits on a small, imperfect orange globe with wisps of cloud around its circumference, against an almost blank mottled blue background. The figure is illuminated faintly from behind, as if by starlight, and also directly from the front as if the observer is the source of light. Watts's use of light and tone avoids the clear definition of shapes, creating a shimmering and dissolving effect more typically associated with

text: pastel

text: work than with oil painting.

text: A black light lamp emits long-wave UVA radiation and little visible light. Fluorescent black light lamps use a phosphor on the inner tube surface, which emits UVA radiation instead of visible light. Some lamps use a deep-bluish-purple Wood's glass optical filter that blocks almost all visible light with wavelengths longer than 400 nanometres. Others use plain glass instead of the more expensive Wood's glass, so they appear light-blue to the eye when operating. A black light may also be formed, very inefficiently, by using a layer of Wood's glass in the envelope for an incandescent bulb. Though cheaper than fluorescent UV lamps, only 0.1% of the input power is converted to usable ultraviolet radiation. Mercury-vapor black lights in ratings up to 1 kW with UV-emitting phosphor and an envelope of Wood's glass are used for theatrical and concert displays. Black lights are used in applications in which extraneous visible light must be minimized; mainly to observe fluorescence, the colored glow that many substances give off when exposed to UV light.    UVA/UVB emitting bulbs are also sold for other special purposes, such as tanning lamps and reptile-keeping.

text: A black light lamp emits long-wave UVA radiation and little visible light. Fluorescent black light lamps use a

text: phosphor

text: on the inner tube surface, which emits UVA radiation instead of visible light. Some lamps use a deep-bluish-purple

text: Wood's glass

text: optical filter that blocks almost all visible light with wavelengths longer than 400 nanometres. Others use plain glass instead of the more expensive Wood's glass, so they appear light-blue to the eye when operating. A black light may also be formed, very inefficiently, by using a layer of Wood's glass in the envelope for an incandescent bulb. Though cheaper than fluorescent UV lamps, only 0.1% of the input power is converted to usable ultraviolet radiation.

text: Mercury-vapor

text: black lights in ratings up to 1 kW with UV-emitting phosphor and an envelope of Wood's glass are used for theatrical and concert displays. Black lights are used in applications in which extraneous visible light must be minimized; mainly to observe

text: fluorescence

text: , the colored glow that many substances give off when exposed to UV light.    UVA/UVB emitting bulbs are also sold for other special purposes, such as

text: tanning lamp

text: s and reptile-keeping.

text: Watts can also be a direct measure of output. In a radiometric sense, an incandescent light bulb is about 80% efficient: 20% of the energy is lost (e.g. by conduction through the lamp base). The remainder is emitted as radiation, mostly in the infrared. Thus, a 60 watt light bulb emits a total radiant flux of about 45 watts. Incandescent bulbs are, in fact, sometimes used as heat sources (as in a chick incubator), but usually they are used for the purpose of providing light. As such, they are very inefficient, because most of the radiant energy they emit is invisible infrared. A compact fluorescent lamp can provide light comparable to a 60 watt incandescent while consuming as little as 15 watts of electricity.

text: Watts can also be a direct measure of output. In a radiometric sense, an incandescent light bulb is about 80% efficient: 20% of the energy is lost (e.g. by conduction through the lamp base). The remainder is emitted as radiation, mostly in the

text: infrared

text: . Thus, a 60 watt light bulb emits a total radiant flux of about 45 watts. Incandescent bulbs are, in fact, sometimes used as heat sources (as in a chick incubator), but usually they are used for the purpose of providing light. As such, they are very inefficient, because most of the radiant energy they emit is invisible infrared. A

text: compact fluorescent lamp

text: can provide light comparable to a 60 watt incandescent while consuming as little as 15 watts of electricity.

text: The player generally has to explore the dungeon to reveal its contents similar to a fog of war. Many roguelikes include factors related to light sources such as a torch to provide illumination to see monsters in nearby squares, and line of sight can also limit what monsters are visible. Dungeons tend to be connected by stairs; lower dungeon levels generally are more difficult than higher ones, so that a character that is underdeveloped may have difficulty by progressing too fast. Dungeon levels and the population of monsters and treasure within them are generated randomly using procedural generation, so that no game is the same on subsequent playthroughs. Most roguelikes have an ultimate goal of either claiming an item located at the deepest level of the dungeon, or to defeat a specific monster that lives on that level. Typical roguelikes include a scoreboard, ranking the player's performance once their game is over (be it through permadeath or completing the objective) based on the amount of treasure, money, and experience earned, and how fast the player completed the game in such cases.

text: The player generally has to explore the dungeon to reveal its contents similar to a

text: fog of war

text: . Many roguelikes include factors related to light sources such as a torch to provide illumination to see monsters in nearby squares, and

text: line of sight

text: can also limit what monsters are visible. Dungeons tend to be connected by stairs; lower dungeon levels generally are more difficult than higher ones, so that a character that is underdeveloped may have difficulty by progressing too fast. Dungeon levels and the population of monsters and treasure within them are generated randomly using

text: procedural generation

text: , so that no game is the same on subsequent playthroughs. Most roguelikes have an ultimate goal of either claiming an item located at the deepest level of the dungeon, or to defeat a specific monster that lives on that level. Typical roguelikes include a scoreboard, ranking the player's performance once their game is over (be it through permadeath or completing the objective) based on the amount of treasure, money, and experience earned, and how fast the player completed the game in such cases.

text: The lighthouse's last active power source was a 500 Watt 110 Volt Philips lamp, fed by the Mains electricity. It showed a white light, with red showing in a sector. Having an intensity of 250,000 cd the white light was visible for  while the red one was visible for . The light was shown at a focal height of .

text: The lighthouse's last active power source was a 500

text: Watt

text: Volt

text: Philips

text: lamp, fed by the

text: Mains electricity

text: . It showed a white light, with red showing in a sector. Having an intensity of 250,000

text: cd

text: the white light was visible for  while the red one was visible for . The light was shown at a focal height of .

text: Luminescence dating techniques observe 'light' emitted from materials such as quartz, diamond, feldspar, and calcite.  Many types of luminescence techniques are utilized in geology, including optically stimulated luminescence (OSL), cathodoluminescence (CL), and thermoluminescence (TL). Thermoluminescence and optically stimulated luminescence are used in archaeology to date 'fired' objects such as pottery or cooking stones, and can be used to observe sand migration.

text: Luminescence dating techniques observe 'light' emitted from materials such as quartz, diamond, feldspar, and calcite.  Many types of luminescence techniques are utilized in geology, including

text: optically stimulated luminescence

text: (OSL),

text: cathodoluminescence

text: (CL), and

text: thermoluminescence

text: (TL).

text: Thermoluminescence

text: and

text: optically stimulated luminescence

text: are used in archaeology to date 'fired' objects such as pottery or cooking stones, and can be used to observe sand migration.

text: The effects of diffraction are often seen in everyday life. The most striking examples of diffraction are those that involve light; for example, the closely spaced tracks on a CD or DVD act as a diffraction grating to form the familiar rainbow pattern seen when looking at a disc. This principle can be extended to engineer a grating with a structure such that it will produce any diffraction pattern desired; the hologram on a credit card is an example. Diffraction in the atmosphere by small particles can cause a bright ring to be visible around a bright light source  like the sun or the moon. A shadow of a solid object, using light from a compact source, shows small fringes near its edges. The speckle pattern which is observed when laser light falls on an optically rough surface is also a diffraction phenomenon.  When deli meat appears to be iridescent, that is diffraction off the meat fibers. All these effects are a consequence of the fact that light propagates as a wave.

text: The effects of diffraction are often seen in everyday life. The most striking examples of diffraction are those that involve light; for example, the closely spaced tracks on a CD or DVD act as a

text: diffraction grating

text: to form the familiar rainbow pattern seen when looking at a disc. This principle can be extended to engineer a grating with a structure such that it will produce any diffraction pattern desired; the

text: hologram

text: on a credit card is an example.

text: Diffraction in the atmosphere

text: by small particles can cause a bright ring to be visible around a bright light source  like the sun or the moon. A shadow of a solid object, using light from a compact source, shows small fringes near its edges. The

text: speckle pattern

text: which is observed when laser light falls on an optically rough surface is also a diffraction phenomenon.  When

text: deli meat

text: appears to be

text: iridescent

text: , that is diffraction off the meat fibers. All these effects are a consequence of the fact that light propagates as a

text: wave

text: Spectroscopy covers many techniques from analytical chemistry to include: atomic absorption and emission (including plasma-based methods such as ICP and ICP-MS); ultraviolet spectroscopy, visible spectroscopy; infrared spectroscopy (including FT-IR and Near-infrared spectroscopy; fluorescence, phosphorescence, and luminescence; Raman spectroscopy and FT-Raman; X-ray (XRF, XRD, and microanalysis); mass spectrometry; magnetic resonance (NMR, EPR, MRI); surface analysis (ESCA, SIMS, Auger); and laser-based spectroscopic techniques.

text: Spectroscopy covers many techniques from

text: analytical chemistry

text: to include:

text: atomic absorption

text: and

text: emission

text: (including plasma-based methods such as

text: ICP

text: and

entity_name: Inductively coupled plasma mass spectrometry

text: ICP-MS

text: ultraviolet spectroscopy

text: visible

text: spectroscopy;

text: infrared spectroscopy

text: (including

text: FT-IR

text: and

text: Near-infrared spectroscopy

text: fluorescence

text: phosphorescence

text: , and

text: luminescence

text: Raman spectroscopy

text: and FT-Raman;

text: X-ray

text: (XRF, XRD, and

text: microanalysis

text: mass spectrometry

text: ; magnetic resonance (

text: NMR

text: EPR

text: MRI

text: surface analysis

text: ESCA

text: SIMS

text: Auger

text: ); and laser-based spectroscopic techniques.

text: Although NdCl itself does not have strong luminescence, it serves as a source of Nd ions for various light emitting materials. The latter include Nd-YAG lasers and Nd-doped optical fiber amplifiers, which amplify light emitted by other lasers. The Nd-YAG laser emits infrared light at 1.064 micrometres and is the most popular solid-state laser (i.e. laser based on a solid medium). The reason for using NdCl rather than metallic neodymium or its oxide, in fabrication of fibers is easy decomposition of NdCl during the chemical vapor deposition; the latter process is widely used for the fiber grows.

text: Although NdCl itself does not have strong

text: luminescence

text: , it serves as a source of Nd ions for various light emitting materials. The latter include

text: Nd-YAG laser

text: s and Nd-doped

text: optical fiber amplifiers

text: , which amplify light emitted by other lasers. The Nd-YAG laser emits

text: infrared

text: light at 1.064 micrometres and is the most popular

text: solid-state laser

text: (i.e. laser based on a solid medium). The reason for using NdCl rather than metallic neodymium or its oxide, in fabrication of fibers is easy decomposition of NdCl during the

text: chemical vapor deposition

text: ; the latter process is widely used for the fiber grows.

text: The light's current characteristic is a white light showing two seconds on, three seconds off (L.Fl.W. 5s), visible for . The current light source is a 12 volt 55 watt quartz halogen lamp.

text: The light's current characteristic is a white light showing two seconds on, three seconds off (L.Fl.W. 5s), visible for . The current light source is a 12

text: volt

text: watt

text: quartz halogen lamp

text: Examples of nonimaging optical devices include optical light guides, nonimaging reflectors, nonimaging lenses or a combination of these devices. Common applications of nonimaging optics include many areas of illumination engineering (lighting).  Examples of modern implementations of nonimaging optical designs include automotive headlamps, LCD backlights, illuminated instrument panel displays, fiber optic illumination devices, LED lights, projection display systems and luminaires.

text: Examples of nonimaging optical devices include optical

text: light guide

text: s, nonimaging

text: reflector

text: s, nonimaging

text: lenses

text: or a combination of these devices. Common applications of nonimaging optics include many areas of illumination engineering (

text: lighting

text: ).  Examples of modern implementations of nonimaging optical designs include

text: automotive headlamp

text: s,

text: LCD backlight

text: s, illuminated

text: instrument panel

text: displays, fiber optic illumination devices,

text: LED light

text: s,

text: projection display system

text: s and

text: luminaire

text: s.

text: The van Cittert–Zernike theorem is crucial to the measurement of the brightness distribution of a source.  With two telescopes, a radio astronomer (or an infrared or submillimeter astronomer) can measure the correlation between the electric field at the two dishes due to some point from the source.  By measuring this correlation for many points on the source, the astronomer can reconstruct the visibility function of the source.  By applying the van Cittert–Zernike theorem, the astronomer can then take the inverse Fourier transform of the visibility function to discover the brightness distribution of the source.  This technique is known as aperture synthesis or synthesis imaging.

text: The van Cittert–Zernike theorem is crucial to the measurement of the brightness distribution of a source.  With two telescopes, a radio astronomer (or an infrared or submillimeter astronomer) can measure the correlation between the electric field at the two dishes due to some point from the source.  By measuring this correlation for many points on the source, the astronomer can reconstruct the visibility function of the source.  By applying the van Cittert–Zernike theorem, the astronomer can then take the inverse Fourier transform of the visibility function to discover the brightness distribution of the source.  This technique is known as

text: aperture synthesis

text: or synthesis imaging.

text: An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. A transmission electron microscope can achieve better than 50 pm resolution and magnifications of up to about 10,000,000x whereas most light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000x.

text: An electron microscope is a microscope that uses a beam of accelerated

text: electron

text: s as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light

text: photon

text: s, electron microscopes have a higher

text: resolving power

text: than

text: light microscope

text: s and can reveal the structure of smaller objects. A transmission electron microscope can achieve better than 50

text: pm

text: resolution and

text: magnification

text: s of up to about 10,000,000x whereas most

text: light microscope

text: s are limited by

text: diffraction

text: to about 200

text: nm

text: resolution and useful magnifications below 2000x.

text: Illumination is usually provided by a battery powered LED, though other electric light sources can be used. The light is projected forward through the scope, and reflects off the back surface of the reticle. Red is the most common colour used, as it least impedes the shooter's natural night vision. This illumination method can be used to provide both daytime and low-light conditions reticle illumination.

text: Illumination is usually provided by a

text: battery

text: powered

text: LED

text: , though other electric light sources can be used. The light is projected forward through the scope, and reflects off the back surface of the reticle. Red is the most common colour used, as it least impedes the shooter's

text: natural night vision

text: . This illumination method can be used to provide both daytime and low-light conditions reticle illumination.

text: Some of the sources of collected imagery information for GEOINT are imagery satellites, cameras on airplanes, Unmanned Aerial Vehicles (UAV) and drones, handheld cameras, maps, or GPS coordinates.  Recently the NGA and IC have increased the use of commercial satellite imagery for intelligence support, such as the use of the IKONOS, Landsat, or SPOT satellites.  These sources produce digital imagery via electro-optical systems, radar, infrared, visible light, multispectral, or hyperspectral imageries.

text: Some of the sources of collected imagery information for GEOINT are imagery satellites, cameras on airplanes,

text: Unmanned Aerial Vehicles

text: (UAV) and drones, handheld cameras, maps, or GPS coordinates.  Recently the NGA and IC have increased the use of commercial satellite imagery for intelligence support, such as the use of the

text: IKONOS

text: Landsat

text: , or

text: SPOT

text: satellites.  These sources produce digital imagery via

text: electro-optical systems

text: radar

text: infrared

text: , visible light,

text: multispectral

text: , or

text: hyperspectral

text: imageries.

text: is about 70°. In a dry objective or condenser, this gives a maximum NA of 0.95. In a high-resolution oil immersion lens, the maximum NA is typically 1.45, when using immersion oil with a refractive index of 1.52. Due to these limitations, the resolution limit of a light microscope using visible light is about 200 nm. Given that the shortest wavelength of visible light is violet (

text: is about 70°. In a dry objective or condenser, this gives a maximum NA of 0.95. In a high-resolution

text: oil immersion lens

text: , the maximum NA is typically 1.45, when using immersion oil with a refractive index of 1.52. Due to these limitations, the resolution limit of a light microscope using

text: visible light

text: is about 200

text: nm

text: . Given that the shortest wavelength of visible light is

text: violet

text: When turned on, an incandescent lamp draws a large inrush current  of about ten times the steady-state current; as the filament heats up, its resistance rises and the current decreases to a steady-state value. A switch designed for an incandescent lamp load can withstand this inrush current.

text: When turned on, an

text: incandescent lamp

text: draws a large

text: inrush current

text: of about ten times the steady-state current; as the filament heats up, its resistance rises and the current decreases to a steady-state value. A switch designed for an incandescent lamp load can withstand this inrush current.

text: This is a list of reflected sources of light examples in contrast to the List of light sources. The list is oriented towards visible light reflection.

text: This is a list of reflected sources of light examples in contrast to the

text: List of light sources

text: . The list is oriented towards visible light reflection.

text: In other words, light is refracted or reflected determining the view, color, or illusion that is seen. The visible extent of light is seen in a chromatic spectrum such as the rainbow. However, visible light is only part of a broad spectrum, which extends beyond the sense of sight. For example, there are other parts of the light spectrum which are in common use today. The microwave spectrum is employed by radar, cell phones, and wireless Internet. The infrared spectrum is used for thermal imaging technologies, which can detect a warm body amidst a cooler night time environment, and infrared illumination is combined with specialized digital cameras for night vision. Astronomers employ the terahertz band for submillimeter observations to answer deep cosmological questions.

text: In other words, light is

text: refract

text: ed or reflected determining the view, color, or illusion that is seen. The visible extent of light is seen in a

text: chromatic spectrum

text: such as the

text: rainbow

text: . However, visible light is only part of a broad spectrum, which extends beyond the sense of sight. For example, there are other parts of the light spectrum which are in common use today. The

text: microwave spectrum

text: is employed by

text: radar

text: cell phone

text: s, and

text: wireless Internet

text: . The

text: infrared spectrum

text: is used for

text: thermal imaging

text: technologies, which can detect a warm body amidst a cooler night time environment, and infrared illumination is combined with specialized

text: digital cameras

text: for

text: night vision

text: . Astronomers employ the

text: terahertz band

text: for

text: submillimeter observations

text: to answer deep

text: cosmological

text: questions.

text: The California smoothtongue is the most common midwater fish off Santa Barbara, California. It makes daily vertical migrations. In the late afternoon and earlier part of the night it is to be found near the surface of the sea feeding mainly on salps and larvaceans; its mouth is adapted to pull in these inactive, gelatinous prey items by suction. It also consumes some ostracods, copepods and fish eggs. In the later part of the night it descends to deeper parts of the sea while in the morning it is at mid-depths. The fish has a double-chambered stomach, the first chamber having a black pigment in its lining which may prevent the light from luminescent prey it has swallowed from being visible from the exterior.

text: The California smoothtongue is the most common midwater fish off

text: Santa Barbara, California

text: . It makes

text: daily vertical migrations

text: . In the late afternoon and earlier part of the night it is to be found near the surface of the sea feeding mainly on

text: salp

text: s and

text: larvacea

text: ns; its mouth is adapted to pull in these inactive, gelatinous prey items by suction. It also consumes some

text: ostracod

text: s,

text: copepod

text: s and fish eggs. In the later part of the night it descends to deeper parts of the sea while in the morning it is at mid-depths. The fish has a double-chambered stomach, the first chamber having a black pigment in its lining which may prevent the light from

text: luminescent

text: prey it has swallowed from being visible from the exterior.

text: Distance scale window: This feature is found on many EF lenses. This feature, while not a control or switch, is useful to the photographer for determining, or setting, the lens's focus distance. It is used in conjunction with the Focusing ring. When rotated, the distance scale will also rotate to show the changing focus distance. On some lenses the distance scale also has an infrared index. These are shown as red markings below the distance scale. This is used for making focus adjustments when the photographer is doing infrared photography, as lenses typically focus infrared light at a different point than visible light, and therefore achieving correct focus using visible light will result in an out-of-focus infrared image. To make an adjustment, first focus the subject, then turn the Focusing ring so it matches the corresponding infrared index mark.

text: Depth and dimension are rendered by the use of linear perspective, by the overlapping of the layers of shapes, and in particular, as stated by Clark, through the use of tone. This compositional element operates within the picture in a number of ways. First, there is the appearance of natural light within the painted room and beyond it. The pictorial space in the midground and foreground is lit from two sources: by thin shafts of light from the open door, and by broad streams coming through the window to the right. The 20th-century French philosopher and cultural critic Michel Foucault observed that the light from the window illuminates both the studio foreground and the unrepresented area in front of it, in which the king, the queen, and the viewer are presumed to be situated. For José Ortega y Gasset, light divides the scene into three distinct parts, with foreground and background planes strongly illuminated, between which a darkened intermediate space includes silhouetted figures.

text: Depth and dimension are rendered by the use of linear perspective, by the overlapping of the layers of shapes, and in particular, as stated by Clark, through the use of tone. This compositional element operates within the picture in a number of ways. First, there is the appearance of natural light within the painted room and beyond it. The pictorial space in the midground and foreground is lit from two sources: by thin shafts of light from the open door, and by broad streams coming through the window to the right. The 20th-century

text: French philosopher

text: and cultural critic

text: Michel Foucault

text: observed that the light from the window illuminates both the studio foreground and the unrepresented area in front of it, in which the king, the queen, and the viewer are presumed to be situated. For

text: José Ortega y Gasset

text: , light divides the scene into three distinct parts, with foreground and background planes strongly illuminated, between which a darkened intermediate space includes silhouetted figures.

text: The light is clearly coming from the left, but the source is not visible and is unusually harsh. The front of Gentileschi’s body is lit perfectly, but her back is obscured. Across the forehead and cheeks and down the side of the neck and left shoulder a clear line separates the light from the dark, a chiaroscuro technique which was used frequently during the Baroque era to add a sense of drama.

text: The light is clearly coming from the left, but the source is not visible and is unusually harsh. The front of Gentileschi’s body is lit perfectly, but her back is obscured. Across the forehead and cheeks and down the side of the neck and left shoulder a clear line separates the light from the dark, a

text: chiaroscuro

text: technique which was used frequently during the Baroque era to add a sense of drama.

text: The device consists of a light source illuminating the material to be measured and a sensor that captures light reflected from that material. The light source should be able to illuminate and the sensor should be able to capture data from a hemisphere around the target. The hemispherical rotation dimensions of the sensor and light source are the four dimensions of the BRDF. The 'gonio' part of the word refers to the device's ability to measure at different angles.

text: The device consists of a light source illuminating the material to be measured and a

text: sensor

text: that captures light reflected from that material. The light source should be able to

text: illuminate

text: and the sensor should be able to capture data from a

text: hemisphere

text: around the target. The hemispherical rotation

text: dimension

text: s of the sensor and light source are the four dimensions of the BRDF. The 'gonio' part of the word refers to the device's ability to measure at different angles.

text: The carbon button lamp is a single-electrode incandescent lamp invented by Nikola Tesla.  A carbon button lamp contains a small carbon sphere positioned in the center of an evacuated glass bulb.  This type of lamp must be driven by high-frequency alternating current, and depends on an electric arc or perhaps a vacuum arc to produce high current around the carbon electrode.  The carbon electrode is then heated to incandescence by collisions by ions which constitute the electric current.  Tesla found that these lamps could be used as powerful sources of ionizing radiation.

text: The carbon button lamp is a single-

text: electrode

text: incandescent lamp invented by

text: Nikola Tesla

text: .  A

text: carbon

text: button lamp contains a small carbon sphere positioned in the center of an evacuated glass bulb.  This type of lamp must be driven by high-frequency

text: alternating current

text: , and depends on an

text: electric arc

text: or perhaps a

text: vacuum arc

text: to produce high

text: current

text: around the carbon electrode.  The carbon electrode is then heated to

text: incandescence

text: by collisions by ions which constitute the electric current.  Tesla found that these lamps could be used as powerful sources of

text: ionizing radiation

text: Luminox watches are advertised to possess "always visible technology."  The watch hands and markers contain tritium insets which provide long-term luminescence, as opposed to phosphorescent markers used in other watches, which must be charged by a light source.

text: Luminox watches are advertised to possess "always visible technology."  The watch hands and markers contain

text: tritium

text: insets which provide

text: long-term luminescence

text: , as opposed to

text: phosphorescent

text: markers used in other watches, which must be charged by a light source.

text: Solar cells are described as being photovoltaic irrespective of whether the source is sunlight or an artificial light. They are used as a photodetector (for example infrared detectors), detecting light or other electromagnetic radiation near the visible range, or measuring light intensity.

text: Solar cells are described as being

text: photovoltaic

text: irrespective of whether the source is

text: sunlight

text: or an artificial light. They are used as a

text: photodetector

text: (for example

text: infrared detector

text: s), detecting light or other

text: electromagnetic radiation

text: near the visible range, or measuring light intensity.

text: Baryonic matter is the part of the universe that is made of baryons (including all atoms). This part of the universe does not include dark energy, dark matter, black holes or various forms of degenerate matter, such as compose white dwarf stars and neutron stars. Microwave light seen by Wilkinson Microwave Anisotropy Probe (WMAP), suggests that only about 4.6% of that part of the universe within range of the best telescopes (that is, matter that may be visible because light could reach us from it), is made of baryonic matter. About 23% is dark matter, and about 72% is dark energy.

text: Baryonic matter is the part of the universe that is made of baryons (including all atoms). This part of the universe does not include

text: dark energy

text: dark matter

text: black holes

text: or various forms of degenerate matter, such as compose

text: white dwarf

text: stars and

text: neutron star

text: s. Microwave light seen by

text: Wilkinson Microwave Anisotropy Probe

text: (WMAP), suggests that only about 4.6% of that part of the universe within range of the best

text: telescope

text: s (that is, matter that may be visible because light could reach us from it), is made of baryonic matter. About 23% is dark matter, and about 72% is dark energy.

text: Developments in electronics also made it possible for the first time to measure the frequency of light in or near the visible region of the spectrum, instead of inferring the frequency from the wavelength and the speed of light. Although visible and infrared frequencies were still too high to be directly measured, it was possible to construct a "chain" of laser frequencies that, by suitable multiplication, differ from each other by only a directly measurable frequency in the microwave region. The frequency of the light from the methane-stabilized laser was found to be  THz.

text: Developments in electronics also made it possible for the first time to measure the frequency of light in or near the visible region of the spectrum, instead of inferring the frequency from the wavelength and the

text: speed of light

text: . Although visible and infrared frequencies were still too high to be directly measured, it was possible to construct a "chain" of laser frequencies that, by suitable multiplication, differ from each other by only a directly measurable frequency in the

text: microwave

text: region. The frequency of the light from the methane-stabilized laser was found to be  THz.

text: In 1925, the light was upgraded to a 35mm incandescent gas mantle fueled by pressurised kerosene, with an intensity of 225,000 cd, visible for . In 1927 the lens was replaced with refurbished lens from Cape Cleveland Light.

text: In 1925, the light was upgraded to a 35mm

text: incandescent gas mantle

text: fueled by pressurised

text: kerosene

text: , with an intensity of 225,000 cd, visible for . In 1927 the lens was replaced with refurbished lens from

text: Cape Cleveland Light

text: The Trick 'r Treat attraction is inspired by the Trick 'r Treat film and "Season's Greetings" both by writer and director Michael Dougherty. The attraction is built as a life-size pop up book entirely in black and white. Guests walk through series of rooms themed around rules of halloween including: 1) always wear a costume 2) pass out treats 3) never blow out a jack-o-lantern and 4) always check your candy.  This highly artist attraction utilizes visible luminescent paints which are black light reactive, further creating a realistic feeling pop-up book.

text: The Trick 'r Treat attraction is inspired by the

text: Trick 'r Treat

text: film and "Season's Greetings" both by writer and director

text: Michael Dougherty

text: . The attraction is built as a life-size pop up book entirely in black and white. Guests walk through series of rooms themed around rules of halloween including: 1) always wear a costume 2) pass out treats 3) never blow out a jack-o-lantern and 4) always check your candy.  This highly artist attraction utilizes visible

text: luminescent paints

text: which are black light reactive, further creating a realistic feeling pop-up book.

text: Journal of Luminescence (ISSN 0953-4075) is a peer-reviewed scientific journal, published monthly.

text: Journal of Luminescence (ISSN 0953-4075) is a

text: peer-review

text: ed

text: scientific journal

text: , published monthly.

text: Auxiliary lighting is light used for illumination, to supplement factory-installed headlights or to illuminate areas to the side of or behind the vehicle. It is typically white or near-white light. Some emergency scenes require additional lighting if the emergency workers are to be able to effectively deal with the emergency. Also, building numbers are often obscured by darkness, making it difficult for emergency workers to find the scene of an emergency. For these reasons, emergency vehicles are often equipped with auxiliary lighting, such as:

text: For relatively small distances between the light source and observer, the intensity of the skyglow contribution from a single source of light is inversely proportional to the distance between the source and the observer (falls off as 1/r). This can be understood as follows: The illumination of any portion of atmosphere visible by the observer falls as 1/r, but the path length of illuminated air along any given line of sight which is illuminated comparably to the brightest illumination grows linearly with distance; together, this gives a 1/r dependence. This is valid when the distance between the source and observer is smaller than the scale height of the atmosphere. At distances much larger, where the path length of illuminated air is limited by the height of the atmosphere itself, this becomes an inverse-square (1/r) dependence.

text: For relatively small distances between the light source and observer, the intensity of the skyglow contribution from a single source of light is inversely proportional to the distance between the source and the observer (falls off as 1/r). This can be understood as follows: The illumination of any portion of atmosphere visible by the observer falls as 1/r, but the path length of illuminated air along any given line of sight which is illuminated comparably to the brightest illumination grows linearly with distance; together, this gives a 1/r dependence. This is valid when the distance between the source and observer is smaller than the

text: scale height

text: of the atmosphere. At distances much larger, where the path length of illuminated air is limited by the height of the atmosphere itself, this becomes an inverse-square (1/r) dependence.

text: The "She's a Bitch" video was directed by Hype Williams on May 1, 1999; similar to his other clips for Elliott, Williams makes extensive use of unique effects, costuming, and sets. Highlights of the video include Elliott and her dancers being raised from underwater on a giant hydraulic "M", and also a complete set made from Electro Luminescent lighting. Although EL lighting is cheap and readily available today, in 1999 it was not. Experts had to be flown in from Germany to construct the set, which even included an EL costume.

text: The "She's a Bitch" video was directed by

text: Hype Williams

text: on May 1, 1999; similar to his other clips for Elliott, Williams makes extensive use of unique effects, costuming, and sets. Highlights of the video include Elliott and her dancers being raised from underwater on a giant hydraulic "M", and also a complete set made from

text: Electro Luminescent lighting

text: . Although EL lighting is cheap and readily available today, in 1999 it was not. Experts had to be flown in from

text: Germany

text: to construct the set, which even included an EL costume.

text: The definition tells us that 1 watt of pure green 555 nm light is "worth" 683 lumens. It does not say anything about other wavelengths. Because lumens are photometric units, their relationship to watts depends on the wavelength according to how visible the wavelength is. Infrared and ultraviolet radiation, for example, are invisible and do not count. One watt of infrared radiation (which is where most of the radiation from an incandescent bulb falls) is worth zero lumens. Within the visible spectrum, wavelengths of light are weighted according to a function called the "photopic spectral luminous efficiency." According to this function, 700 nm red light is only about 0.4% as efficient as 555 nm green light. Thus, one watt of 700 nm red light is "worth" only 2.7 lumens.

text: The Glowing Plant project plans to use bacterial bio-luminescent systems to engineer novelty glowing Arabidopsis thaliana plants. Longer term they hypothesize that maybe such systems could be used to create eco-friendly sustainable light sources.

text: The

text: Glowing Plant project

text: plans to use bacterial bio-luminescent systems to engineer novelty glowing

text: Arabidopsis thaliana

text: plants. Longer term they hypothesize that maybe such systems could be used to create eco-friendly sustainable light sources.

text: There were 35 standard gondolas, each able to carry up to six adults and two children, and one VIP gondola able to carry up to four people, giving a maximum capacity of 284 (although the typical ridership at any one time was expected to be 200). As demonstrated by its move from South Africa to England, the structure is fully transportable and its operator Paramount Attractions claimed it could be disassembled and removed in two weeks. Commentary was available on the views and buildings visible during the ride, which consisted of three full rotations lasting about 12 minutes in total. Opening hours were 10:00 am to 11:00 pm all year, and the wheel will be lit at night; the extent of the illumination was reduced from that proposed in the planning application, which included lights on the supporting struts and some flashing lights.

text: The illumination of the subject is also a key element in creating an artistic piece, and the interplay of light and shadow is a valuable method in the artist's toolbox. The placement of the light sources can make a considerable difference in the type of message that is being presented. Multiple light sources can wash out any wrinkles in a person's face, for instance, and give a more youthful appearance. In contrast, a single light source, such as harsh daylight, can serve to highlight any texture or interesting features.

text: The

text: illumination

text: of the subject is also a key element in creating an artistic piece, and the interplay of

text: light and shadow

text: is a valuable method in the artist's toolbox. The

text: placement of the light sources

text: can make a considerable difference in the type of message that is being presented. Multiple light sources can wash out any wrinkles in a person's face, for instance, and give a more youthful appearance. In contrast, a single light source, such as harsh daylight, can serve to highlight any texture or interesting features.

text: Since about 2000, FDTD techniques have emerged as a primary means to computationally model many scientific and engineering problems dealing with electromagnetic wave interactions with material structures.  Current FDTD modeling applications range from near-DC (ultralow-frequency geophysics involving the entire Earth-ionosphere waveguide) through microwaves (radar signature technology, antennas, wireless communications devices, digital interconnects, biomedical imaging/treatment) to visible light (photonic crystals, nanoplasmonics, solitons, microscopy and lithography, and biophotonics).  At least 28 commercial FDTD software suites and 16 free-software/open-source or closed-source FDTD projects are available.  To a large degree, all of these software constructs derive directly from FDTD techniques first reported by Prof. Taflove and his students over the past 40 years.

text: Since about 2000, FDTD techniques have emerged as a primary means to computationally model many scientific and engineering problems dealing with

text: electromagnetic wave

text: interactions with material structures.  Current FDTD modeling applications range from near-DC (ultralow-frequency geophysics involving the entire Earth-ionosphere waveguide) through microwaves (radar signature technology, antennas, wireless communications devices, digital interconnects, biomedical imaging/treatment) to visible light (photonic crystals, nanoplasmonics, solitons, microscopy and lithography, and biophotonics).  At least 28 commercial FDTD software suites and 16 free-software/open-source or closed-source FDTD projects are available.  To a large degree, all of these software constructs derive directly from FDTD techniques first reported by Prof. Taflove and his students over the past 40 years.

text: is the aperture. For visible light (

text: is the aperture. For

text: visible light

text: Light transmission (for this article, the perceivable visible spectrum between 390 nm and 750 nm is considered) through glass is diminished either by light reflection or light absorption of the glazing material. The total light transferred through the glazing material (light transmission) is reduced by reflection and/or absorption. In art framing, light reflection causes glare, while light absorption also may cause the transmitted colors to be dulled or distorted. While type of the glass substrate will affect the light absorption of the glazing, the surface treatment can affect light scattering, light reflection and in some cases, light absorption. There are various glazing options to achieve this goal as explained in the following sections on Types of Picture Framing Glass.

text: Light transmission

text: (for this article, the perceivable

text: visible spectrum

text: between 390 nm and 750 nm is considered) through glass is diminished either by

text: light reflection

text: or

text: light absorption

text: of the glazing material. The total light transferred through the glazing material (light transmission) is reduced by reflection and/or absorption. In art framing,

text: light reflection

text: causes

text: glare

text: , while

text: light absorption

text: also may cause the transmitted colors to be dulled or distorted. While type of the glass substrate will affect the

text: light absorption

text: of the glazing, the surface treatment can affect

text: light scattering

text: light reflection

text: and in some cases,

text: light absorption

text: . There are various glazing options to achieve this goal as explained in the following sections on Types of Picture Framing Glass.

text: The term calorescence is rarely seen in use today, whereas the term fluorescence is common. One reason is that there isn't a physical explanation for calorescence that's specific to calorescence. Relatedly, the physical explanations for some types of fluorescence behavior are also explanations for calorescence and the word fluorescence has been preferred and expanded in customary usage to include calorescence. Another reason is that there isn't a widely used practical application attached to the word calorescence, whereas there is for fluorescence. A related item of physics terminology today is the so-called "Anti-Stokes Shift". A Stokes shift refers to molecular absorptions of radiant energy of higher frequencies followed by emissions of lower frequencies; and an anti-Stokes shift refers to absorptions of lower frequencies followed by emissions of higher frequencies. With this terminology, practical applications are attached to the term "anti-Stokes photoluminescence" in materials science including semiconductors (see examples). Equal terminology in use in laser science is "infrared upconversion", "upconversion luminescence", or simply "upconversion" (see examples). This terminology is usually contemplating luminescence, as opposed to incandescence, whereas the word Calorescence belongs to the 19th century when the only known upconversion methods were of the incandescent kind.

text: The term calorescence is rarely seen in use today, whereas the term fluorescence is common. One reason is that there isn't a physical explanation for calorescence that's specific to calorescence. Relatedly, the physical explanations for some types of fluorescence behavior are also explanations for calorescence and the word fluorescence has been preferred and expanded in customary usage to include calorescence. Another reason is that there isn't a widely used practical application attached to the word calorescence, whereas there is for fluorescence. A related item of physics terminology today is the so-called "

text: Anti-Stokes Shift

text: ". A Stokes shift refers to molecular absorptions of radiant energy of higher frequencies followed by emissions of lower frequencies; and an anti-Stokes shift refers to absorptions of lower frequencies followed by emissions of higher frequencies. With this terminology, practical applications are attached to the term "anti-Stokes photoluminescence" in materials science including semiconductors (see examples). Equal terminology in use in laser science is "infrared upconversion", "upconversion luminescence", or simply "

text: upconversion

text: " (see examples). This terminology is usually contemplating

text: luminescence

text: , as opposed to

text: incandescence

text: , whereas the word Calorescence belongs to the 19th century when the only known upconversion methods were of the incandescent kind.

text: Shadow noise or luminescence noise is an effect that digital lightening has on an image, specifically on the darker, or shadowed areas of the image. Brightening the image, especially in underexposed photos, brings out the "shadow noise" in such areas. Noise in digital photography is the analog to film photography's grain, or visible distortion that appears on an image. However, film grain tends to be less noticeable than noise, which can appear as distorted colors or artifacts on an image. A suitable analogy would be when a television begins to "snow" or experience "white noise", when static begins to appear on the screen, distorting or obscuring the image.

text: Shadow noise or luminescence noise is an effect that

text: digital lightening

text: has on an image, specifically on the darker, or shadowed areas of the image. Brightening the image, especially in underexposed photos, brings out the "shadow noise" in such areas. Noise in digital photography is the analog to film photography's grain, or visible distortion that appears on an image. However, film grain tends to be less noticeable than noise, which can appear as distorted colors or artifacts on an image. A suitable analogy would be when a television begins to "snow" or experience "white noise", when static begins to appear on the screen, distorting or obscuring the image.

text: Devils Island, situated in the Atlantic Ocean – amid shoals and other hazards for seafarers, was the cause of numerous shipwrecks. The residents often used their own fishing boats and risked their lives in attempts to rescue the crews of wrecked ships. In 1837, a wooden beacon painted white was erected on the southern point of the island as a navigational aid, but because it was only visible during the day time, in 1851 a Halifax group made up of merchants, traders, and sea mariners presented a petition to the lieutenant-governor for a lighthouse to be built which the Assembly approved. In 1852, an octagonal lighthouse with an accompanying mirrored light was constructed near the shore on the southwest corner of the island. In 1877, a second lighthouse was built 175 yards east of the first one. The western light “was open all round, while the eastern one was dark on its northern side” (Boileau, Historic Eastern Passage, 103). Both white lights were visible from a distance of thirteen miles. In 1949, the first lighthouse erected was demolished and the light in the second was changed to flashing red and was visible for thirteen miles. In 1959, it was changed to a flashing white and amber light and was visible for eleven miles. In 1967, an automatic beacon flashing white was installed making the lighthouse keeper unnecessary, and all permanent human habitation on the island ceased after this event.  Devils Island has been deserted for many years now and the remaining standing buildings, like the lighthouse keeper’s house, have been exposed to yearly seasonal weather without any maintenance and show signs of great disrepair. While under the care of the Canadian Coast Guard, the cupola of this second lighthouse was dismantled and discarded on the beach.

text: Devils Island, situated in the

text: Atlantic Ocean

text: – amid shoals and other hazards for seafarers, was the cause of numerous shipwrecks. The residents often used their own fishing boats and risked their lives in attempts to rescue the crews of wrecked ships. In 1837, a wooden beacon painted white was erected on the southern point of the island as a

text: navigational aid

text: , but because it was only visible during the day time, in 1851 a Halifax group made up of merchants, traders, and sea mariners presented a petition to the

text: lieutenant-governor

text: Most existing X-ray telescopes use CCD detectors, similar to those in visible-light cameras. In visible-light, a single photon can produce a single electron of charge in a pixel, and an image is built up by accumulating many such charges from many photons during the exposure time. When an X-ray photon hits a CCD, it produces enough charge (hundreds to thousands of electrons, proportional to its energy) that the individual X-rays have their energies measured on read-out.

text: Most existing X-ray telescopes use

text: CCD

text: detectors, similar to those in visible-light cameras. In visible-light, a single photon can produce a single electron of charge in a pixel, and an image is built up by accumulating many such charges from many photons during the exposure time. When an X-ray photon hits a CCD, it produces enough charge (hundreds to thousands of electrons, proportional to its energy) that the individual X-rays have their energies measured on read-out.

text: The original use of the mineral yttria and the purpose of its extraction from mineral sources was as part of the process of making gas mantles and other products for turning the flames of artificially-produced gases (initially hydrogen, later coal gas, paraffin, or other products) into human-visible light. This use is almost obsolete - thorium and cerium oxides are larger components of such products these days.

text: While there is some correlation between the percentages of visible light and UV that pass through the same fabric, it is not a strong relationship. With new-technology textiles designed for the sole purpose of UV blocking, it is not always possible to judge the UV protection level simply by holding up the fabric and examining how much visible light passes through.

text: While there is some correlation between the percentages of

text: visible light

text: and UV that pass through the same fabric, it is not a strong relationship. With new-technology textiles designed for the sole purpose of UV blocking, it is not always possible to judge the UV protection level simply by holding up the fabric and examining how much visible light passes through.

text: WMSAMF presented the memorial design to the CFA and NCPC again in October 1994. In response to previous CFA concerns, the steps in the niches were slightly recessed to help retain the appearance that the niches still existed. Although the lighting for the illuminated skylights had been softened as well, J. Carter Brown still claimed they would overwhelm the Hemicycle and upstage Arlington House and the Lincoln Memorial (both of which were also illuminated at night). With the CFA apparently convinced that the lighting was out of the question, Weiss and Manfredi introduced lighting expert Howard Brandston, a fellow of the Illuminating Engineering Society of North America. Brandston testified that no lighting was intended for the skylights themselves; lighting would only come from below, in the illuminated memorial galleries. Furthermore, he said, only a "soft glow" would be visible through the balustrade at the front of the Hemicycle. This convinced the CFA, which withdrew its objections. CFA members also expressed concern about the visibility of the glass doors on the north and south sides of the memorial, so Weiss and Manfredi agreed to recess these even further. But most of the CFA's discussion regarded the Hemicycle itself and how much disruption there could be to its existing architecture. Weiss and Manfredi continued to retain two rows of American linden trees on either side of the plaza. These had been moved back from the centerline but continued to screen the cemetery main gates. The CFA wanted these moved back even more, and the pleaching removed so that almost nothing was screened. The trees were intended to form a sort of entrance to the memorial, but the CFA did not like that approach. Weiss and Manfredi also had given more detail to the water feature. Now they planned for the water feature in the central niche to flow outward into the reflecting pool. Almost none of the commissioners liked the rill from the water feature to the pool, calling it a "Middle Eastern" design that did not fit with the Neoclassical Hemicycle. Brown commented that he had no aesthetic problems with the rill, and that it added a "memorial" quality to the design. At the end of the meeting, the CFA approved the memorial design, but asked that their concerns about the plaza be addressed further.

text: WMSAMF presented the memorial design to the CFA and NCPC again in October 1994. In response to previous CFA concerns, the steps in the niches were slightly recessed to help retain the appearance that the niches still existed. Although the lighting for the illuminated skylights had been softened as well, J. Carter Brown still claimed they would overwhelm the Hemicycle and upstage Arlington House and the Lincoln Memorial (both of which were also illuminated at night). With the CFA apparently convinced that the lighting was out of the question, Weiss and Manfredi introduced lighting expert Howard Brandston, a fellow of the

entity_name: Illuminating Engineering Society of North America

text: Illuminating Engineering Society of North America

text: . Brandston testified that no lighting was intended for the skylights themselves; lighting would only come from below, in the illuminated memorial galleries. Furthermore, he said, only a "soft glow" would be visible through the

text: balustrade

text: at the front of the Hemicycle. This convinced the CFA, which withdrew its objections. CFA members also expressed concern about the visibility of the glass doors on the north and south sides of the memorial, so Weiss and Manfredi agreed to recess these even further. But most of the CFA's discussion regarded the Hemicycle itself and how much disruption there could be to its existing architecture. Weiss and Manfredi continued to retain two rows of

text: American linden trees

text: on either side of the plaza. These had been moved back from the centerline but continued to screen the cemetery main gates. The CFA wanted these moved back even more, and the

text: pleaching

text: removed so that almost nothing was screened. The trees were intended to form a sort of entrance to the memorial, but the CFA did not like that approach. Weiss and Manfredi also had given more detail to the water feature. Now they planned for the water feature in the central niche to flow outward into the reflecting pool. Almost none of the commissioners liked the rill from the water feature to the pool, calling it a "Middle Eastern" design that did not fit with the Neoclassical Hemicycle. Brown commented that he had no aesthetic problems with the rill, and that it added a "memorial" quality to the design. At the end of the meeting, the CFA approved the memorial design, but asked that their concerns about the plaza be addressed further.

text: Turkish or Ottoman illumination covers non-figurative painted or drawn decorative art in books or on sheets in muraqqa or albums, as opposed to the figurative images of the Ottoman miniature.  In Turkish it is called “tezhip”, an Arabic word which means “ornamenting with gold”. It was a part of the Ottoman Book Arts together with the Ottoman miniature (taswir), calligraphy (hat), Islamic calligraphy, bookbinding (cilt) and paper marbling (ebru). In the Ottoman Empire, illuminated and illustrated manuscripts were commissioned by the Sultan or the administrators of the court. In Topkapi Palace, these manuscripts were created by the artists working in Nakkashane, the atelier of the miniature and illumination artists. Both religious and non-religious books could be illuminated. Also sheets for albums levha consisted of illuminated calligraphy (hat) of tughra, religious texts, verses from poems or proverbs, and purely decorative drawings.

text: Turkish or Ottoman illumination covers non-figurative painted or drawn decorative art in books or on sheets in

text: muraqqa

text: Ottoman miniature

text: .  In

text: Turkish

text: it is called “tezhip”, an Arabic word which means “ornamenting with gold”. It was a part of the Ottoman Book Arts together with the Ottoman miniature (taswir), calligraphy (hat),

text: Islamic calligraphy

text: , bookbinding (cilt) and

text: paper marbling

text: (ebru). In the Ottoman Empire,

text: illuminated and illustrated manuscripts

text: Topkapi Palace

text: , these manuscripts were created by the artists working in

text: Nakkashane

text: , the atelier of the miniature and illumination artists. Both religious and non-religious books could be illuminated. Also sheets for albums levha consisted of illuminated calligraphy (hat) of

text: tughra

text: In 1968, the installation of a 4th Order electrically operated revolving optic replaced the original 2nd Order optic with a pressurised vapour kerosene "Hood" mantle burner. The light source was changed to a 100-volt/1,000-watt incandescent bulb producing 350,000 candelas of light intensity with a visibility range of . The power supply came from one of the three generators installed in a generator room built close to the keeper's room. As the rotation was electrically driven by motors, the crew was reduced to four men.

text: In 1968, the installation of a 4th Order electrically operated revolving optic replaced the original 2nd Order optic with a pressurised vapour kerosene "Hood" mantle burner. The light source was changed to a 100-volt/1,000-watt

text: incandescent bulb

text: producing 350,000

text: candela

text: s of light intensity with a visibility range of . The power supply came from one of the three

text: generators

text: installed in a generator room built close to the keeper's room. As the rotation was electrically driven by motors, the crew was reduced to four men.

text: Electromagnetic radiation with a wavelength between 380 nm and 760 nm (400–790 terahertz) is detected by the human eye and perceived as visible light. Other wavelengths, especially near infrared (longer than 760 nm) and ultraviolet (shorter than 380 nm) are also sometimes referred to as light, especially when the visibility to humans is not relevant. White light is a combination of lights of different wavelengths in the visible spectrum. Passing white light through a prism splits it up into the several colors of light observed in the visible spectrum between 400 nm and 780 nm.

text: Electromagnetic radiation with a

text: wavelength

text: between 380

text: nm

text: and 760 nm (400–790 terahertz) is detected by the human eye and perceived as visible light. Other wavelengths, especially near infrared (longer than 760 nm) and ultraviolet (shorter than 380 nm) are also sometimes referred to as light, especially when the visibility to humans is not relevant. White light is a combination of lights of different wavelengths in the visible spectrum. Passing white light through a prism splits it up into the several colors of light observed in the visible spectrum between 400 nm and 780 nm.

text: Within Illumination each "Block" is a self-contained piece of functionality. Blocks are tied together via "inputs" and "outputs" which pass no data, and only serve to structure the flow of the application. Illumination also contains a "Window Editor" to allow for the building of applications with simple user interfaces.

text: In fluorescence the visible light component—sometimes known as "white light"—tends to be reflected and perceived normally, as colour; while the UV component of light is modified, 'stepped down' energetically into longer wavelengths, producing additional visible light frequencies, which are then emitted alongside the reflected white light. Human eyes perceive these changes as the unusual 'glow' of fluorescence.

text: In fluorescence the

text: visible light

text: component—sometimes known as "

text: white light

text: "—tends to be reflected and perceived normally, as colour; while the UV component of light is modified, 'stepped down' energetically into longer wavelengths, producing additional visible light frequencies, which are then emitted alongside the reflected white light. Human eyes perceive these changes as the unusual 'glow' of fluorescence.

text: Optically stimulated luminescence (OSL) dating constrains the time at which sediment was last exposed to light. During sediment transport, exposure to sunlight 'zeros' the luminescence signal. Upon burial, the sediment accumulates a luminescence signal as natural ambient radiation gradually ionises the mineral grains.

text: Ilagan is one of the few places in the Cagayan Valley Region that has a continuous freeway lighting system. The city government have managed to install incandescent highway lights along the national road from Barangay Alibagu in the south all the way to Barangay San Juan in the north.

text: Optics, the study of light, is concerned not only with visible light but also with infrared and ultraviolet radiation, which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light. Heat is a form of energy, the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy. Electricity and magnetism have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an electric current gives rise to a magnetic field, and a changing magnetic field induces an electric current. Electrostatics deals with electric charges at rest, electrodynamics with moving charges, and magnetostatics with magnetic poles at rest.

text: Optics

text: , the study of

text: light

text: , is concerned not only with

text: visible light

text: but also with

text: infrared

text: and

text: ultraviolet radiation

text: , which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light.

text: Heat

text: is a form of

text: energy

text: , the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy.

text: Electricity

text: and

text: magnetism

text: have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an

text: electric current

text: gives rise to a

text: magnetic field

text: , and a changing magnetic field induces an electric current.

text: Electrostatics

text: deals with

text: electric charge

text: s at rest,

text: electrodynamics

text: with moving charges, and

text: magnetostatics

text: with magnetic poles at rest.

text: According to the Web of Science, the most-cited papers published in Luminescence  are:

text: According to the

text: Web of Science

text: , the most-cited papers published in Luminescence  are:

text: Cherenkov luminescence imaging (CLI) is an emerging imaging modality, similar to bioluminescence imaging, that captures visible photons emitted by Cherenkov radiation. It basically is the optical imaging of radiotracers that emit charged particles traveling faster than the phase velocity of light in that particular medium. It can be used to quickly evaluate radio tracers in preclinical research   but also to obtain clinical images in patients. While radioactivity itself can not be modified the emitted light provides an opportunity to generate radioactivity-based activatable or "smart" imaging agents that sense for example enzymatic activity.

text: Cherenkov luminescence imaging (CLI) is an emerging imaging modality, similar to

text: bioluminescence imaging

text: , that captures visible photons emitted by

text: Cherenkov radiation

text: . It basically is the optical imaging of radiotracers that emit charged particles traveling faster than the phase velocity of light in that particular medium. It can be used to quickly evaluate radio tracers in preclinical research   but also to obtain clinical images in patients. While radioactivity itself can not be modified the emitted light provides an opportunity to generate radioactivity-based activatable or "smart" imaging agents that sense for example enzymatic activity.

text: Nowadays, in all forms of digital X-ray imaging (radiography, fluoroscopy, and CT) the conversion of X-ray energy into visible light can be achieved by the same types of electronic sensors, such as flat panel detectors, which convert the X-ray energy into electrical signals, small bursts of current that convey information that a computer can analyze, store, and output as images. As fluorescence is a special case of luminescence, digital X-ray imaging is conceptually similar to digital gamma ray imaging (scintigraphy, SPECT, and PET) in that in both of these imaging mode families, the information conveyed by the variable attenuation of invisible electromagnetic radiation as it passes through tissues with various radiodensities is converted by an electronic sensor into an electric signal that is processed by a computer and outputted as a visible-light image.

text: Nowadays, in all forms of digital X-ray imaging (radiography, fluoroscopy, and CT) the conversion of X-ray energy into visible light can be achieved by the same types of electronic sensors, such as

text: flat panel detector

text: s, which convert the X-ray energy into electrical

text: signals

text: , small bursts of

text: current

text: that convey

text: information

text: that a computer can analyze, store, and output as images. As fluorescence is a special case of

text: luminescence

text: , digital X-ray imaging is

text: concept

text: ually similar to digital

text: gamma ray

text: imaging (

text: scintigraphy

entity_name: Single-photon emission computed tomography

text: SPECT

text: , and

text: PET

text: ) in that in both of these imaging mode families, the information conveyed by the variable attenuation of invisible electromagnetic radiation as it passes through tissues with various radiodensities is converted by an electronic sensor into an electric signal that is

text: processed by a computer

text: and outputted as a visible-light image.

text: Single pole illuminated switches derive the power to energize their in-built illuminating source (usually, a "neon" lamp) from the current passing through the lamp(s) which they control. Such switches work satisfactorily with incandescent lamps, halogen lighting and non-electronic fluorescent fixtures, since the small current required for the switch's illuminating source is too small to produce any visible light from such devices controlled by the illuminated switch. However, if used to control compact fluorescent lamps (CFLs), the small amount of current required to energize the lighting source within switch also slowly charges the internal input capacitor in the electronic ballast of the CFL until the voltage across it rises to the point where it produces a brief discharge through the CFL. This cycle may repeat indefinitely, resulting in brief repetitive flashing while the illuminated switch is in the "off" position.

text: Single pole illuminated switches derive the power to energize their in-built illuminating source (usually, a "neon" lamp) from the current passing through the lamp(s) which they control. Such switches work satisfactorily with incandescent lamps, halogen lighting and non-electronic fluorescent fixtures, since the small current required for the switch's illuminating source is too small to produce any visible light from such devices controlled by the illuminated switch. However, if used to control

text: compact fluorescent lamps

text: (CFLs), the small amount of current required to energize the lighting source within switch also slowly charges the internal input capacitor in the electronic

text: ballast

text: of the CFL until the voltage across it rises to the point where it produces a brief discharge through the CFL. This cycle may repeat indefinitely, resulting in brief repetitive flashing while the illuminated switch is in the "off" position.

text: Before electronic light sensitive elements were developed, photometry was done by estimation by the eye.  The relative luminous flux of a source was compared with a standard source. The photometer is placed such that the  illuminance from the source being investigated is equal to the standard source, as the human eye can judge equal illuminance. The relative luminous fluxes can then be calculated as the illuminance decreases proportionally to the inverse square of distance. A standard example of such a photometer consists of a piece of paper with an oil spot on it that makes the paper slightly more transparent. When the spot is not visible from either side, the illuminance from the two sides is equal.

text: Before electronic light sensitive elements were developed,

text: photometry

text: was done by estimation by the eye.  The relative

text: luminous flux

text: of a source was compared with a standard source. The photometer is placed such that the  illuminance from the source being investigated is equal to the standard source, as the human eye can judge equal illuminance. The relative luminous fluxes can then be calculated as the illuminance decreases proportionally to the inverse square of distance. A standard example of such a photometer consists of a piece of paper with an oil spot on it that makes the paper slightly more transparent. When the spot is not visible from either side, the illuminance from the two sides is equal.

text: Luminescence is emission of light by a substance not resulting from heat.

text: In a photographic studio, more powerful and flexible studio flash systems are used. They usually contain a modeling light, an incandescent light bulb close to the flash tube; the continuous illumination of the modeling light lets the photographer visualize the effect of the flash. A system may comprise multiple synchronised flashes for multi-source lighting.

text: In a photographic studio, more powerful and flexible studio flash systems are used. They usually contain a

text: modeling light

text: , an

text: incandescent light bulb

text: close to the flash tube; the continuous illumination of the modeling light lets the photographer visualize the effect of the flash. A system may comprise multiple synchronised flashes for multi-source lighting.

text: Luminescent solar concentrators convert sunlight or other sources of light into preferred frequencies; they concentrate the output for conversion into desirable forms of power, such as electricity.  They rely on luminescence, typically fluorescence, in media such as liquids, glasses, or plastics treated with a suitable coating or dopant. The structures are configured to direct the output from a large input area onto a small converter, where the concentrated energy generates photoelectricity. The objective is to collect light over a large area at low cost; luminescent concentrator panels can be made cheaply from materials such as glasses or plastics, while photovoltaic cells are high-precision, high-technology devices, and accordingly expensive to construct in large sizes.

text: Luminescent solar concentrator

text: s convert sunlight or other sources of light into preferred frequencies; they concentrate the output for conversion into desirable forms of power, such as electricity.  They rely on

text: luminescence

text: , typically

text: fluorescence

text: , in media such as liquids, glasses, or plastics treated with a suitable coating or

text: dopant

text: . The structures are configured to direct the output from a large input area onto a small converter, where the concentrated energy generates

text: photoelectricity

text: . The objective is to collect light over a large area at low cost; luminescent concentrator panels can be made cheaply from materials such as glasses or plastics, while photovoltaic cells are high-precision, high-technology devices, and accordingly expensive to construct in large sizes.

text: For the human eye, the best primary colors of light are red, green, and blue.  Combining the wavelengths of light we see as these colors produces the greatest range of visible color.

text: For the human eye, the best primary colors of light are

text: red

text: green

text: , and

text: blue

text: .  Combining the wavelengths of light we see as these colors produces the greatest range of visible color.

text: Nearly all of the energy input into the reaction is transformed into light. The reaction is 80% to 90% efficient.  As a comparison, the incandescent light bulb only converts about 10% of its energy into light. and a 150 lumen per Watt (lm/W) LED converts 20% of input energy to visible light.

text: Nearly all of the energy input into the reaction is transformed into light. The reaction is 80% to 90% efficient.  As a comparison, the

text: incandescent light bulb

text: only converts about 10% of its

text: energy

text: into light. and a 150 lumen per Watt (lm/W) LED converts 20% of input energy to visible light.

text: Certain image capturing devices are capable of producing images through materials that are opaque to visible light, including clothing. These devices form images by using electromagnetic radiation outside the visible range. Infrared and terahertz-wave cameras are capable of creating images through clothing, though these images differ from what would be created with visible light.

text: There are many non-incandescent light sources, such as the fluorescent lamp, high-intensity discharge lamps and LED lamps, which have higher luminous efficiency, and some have been designed to be retrofitted in fixtures for incandescent lights. These devices produce light by luminescence. These lamps produce discrete spectral lines and do not have the broad "tail" of invisible infrared emissions. By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution, the spectrum emitted can be tuned to mimic the appearance of incandescent sources, or other different color temperatures of white light. Due to the discrete spectral lines rather than a continuous spectrum, the light is not ideal for applications such as photography and cinematography.

text: There are many non-incandescent light sources, such as the fluorescent lamp,

text: high-intensity discharge lamp

text: s and

text: LED lamp

text: s, which have higher luminous efficiency, and some have been designed to be

text: retrofitted

text: in fixtures for incandescent lights. These devices produce light by

text: luminescence

text: . These lamps produce discrete

text: spectral line

text: s and do not have the broad "tail" of invisible infrared emissions. By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution, the spectrum emitted can be tuned to mimic the appearance of incandescent sources, or other different

text: color temperature

text: s of white light. Due to the discrete spectral lines rather than a continuous spectrum, the light is not ideal for applications such as photography and cinematography.

text: Early in his career, Henry identified the source of red light emission in gallium phosphide LEDs.  In 1968, he and coworkers reported that the red luminescence originated from an electron-hole pair bound to a nearest neighbor donor-acceptor pair composed of zinc and oxygen.  Subsequently, red as well as green GaP LEDs were manufactured and used as indicator lights in a variety of applications.

text: Early in his career, Henry identified the source of red light emission in

text: gallium phosphide

text: LEDs

text: .  In 1968, he and coworkers reported that the red luminescence originated from an electron-hole pair bound to a nearest neighbor donor-acceptor pair composed of zinc and oxygen.  Subsequently, red as well as green GaP LEDs were manufactured and used as indicator lights in a variety of applications.

text: University Avenue has matured and mellowed somewhat since Berton's unfavourable observation, though paving is still characterized by poured concrete and asphalt for most sidewalks and roadway. Restaurants now dot the southern end of University Avenue. Recently completed at the intersection of University and Queen Street is the Four Seasons Centre, which is the new home of the Canadian Opera Company and the National Ballet of Canada. Osgoode Hall presents stately architecture and a welcome green space. During the holiday season, festive lights illuminate the trees and shrubs of the boulevard. Unlike most major streets in Toronto, there are no rooftop billboards visible from University Avenue due to a bylaw.

text: University Avenue has matured and mellowed somewhat since Berton's unfavourable observation, though paving is still characterized by poured concrete and asphalt for most sidewalks and roadway. Restaurants now dot the southern end of University Avenue. Recently completed at the intersection of University and

text: Queen Street

text: is the

text: Four Seasons Centre

text: , which is the new home of the

text: Canadian Opera Company

text: and the

text: National Ballet of Canada

text: Osgoode Hall

text: presents stately architecture and a welcome green space. During the holiday season, festive lights illuminate the trees and shrubs of the boulevard. Unlike most major streets in Toronto, there are no rooftop billboards visible from University Avenue due to a bylaw.

text: ULAS J1120+0641 was discovered by the UKIRT Infrared Deep Sky Survey (UKIDSS), using the UK Infrared Telescope, located in Hawaii. The name of the object is derived from UKIDSS Large Area Survey (ULAS), the name of the survey that discovered the quasar, and the location of the quasar in the sky in terms of right ascension (11h 20m) and declination (+06° 41'). This places the quasar in the constellation of Leo, close (on the plane of the sky) to σ Leo. The quasar was discovered by a telescope that operates at infrared wavelengths, which is at longer wavelength and lower energy than visible light. When the light was originally emitted by ULAS J1120+0641, it was in the ultraviolet, with shorter wavelength and higher energy than visible light. The change in energy and wavelength of the light is due to the expanding universe, which imparts a cosmological redshift to all light as it travels through the universe.

text: ULAS J1120+0641 was discovered by the

text: UKIRT Infrared Deep Sky Survey

text: (UKIDSS), using the

text: UK Infrared Telescope

text: , located in

text: Hawaii

text: . The name of the object is derived from UKIDSS Large Area Survey (ULAS), the name of the survey that discovered the quasar, and the location of the quasar in the sky in terms of

text: right ascension

text: (11h 20m) and

text: declination

text: (+06° 41'). This places the quasar in the constellation of

text: Leo

text: , close (on the plane of the sky) to

text: σ Leo

text: . The quasar was discovered by a telescope that operates at

text: infrared

text: wavelength

text: s, which is at longer wavelength and lower energy than

text: visible light

text: . When the light was originally emitted by ULAS J1120+0641, it was in the

text: ultraviolet

text: , with shorter wavelength and higher energy than visible light. The change in energy and wavelength of the light is due to the

text: expanding universe

text: , which imparts a

text: cosmological redshift

text: to all light as it travels through the universe.

text: Szigeti worked together with Zoltan Bay on metal-vapor lamps and fluorescent light sources. They received a U.S. patent on "electroluminescent light sources" that were made of silicon carbide; these light sources were the ancestors of light-emitting diodes (LEDs).

text: Szigeti worked together with Zoltan Bay on metal-vapor lamps and fluorescent light sources. They received a U.S. patent on "electroluminescent light sources" that were made of silicon carbide; these light sources were the ancestors of

text: light-emitting diode

text: s (LEDs).

text: Scintillation detectors uses a photo luminescent source (such as ZnS) which interacts with radiation.  When a radioactive particle decays and strikes the photo luminescent material a photon is released.  This photon is multiplied in a photomultiplier tube which converts light into an electrical signal.  This signal is then processed and converted into a channel.  By comparing the number of counts to the energy level (typically in keV or MeV) the type of decay can be determined.

text: Scintillation

text: detectors uses a photo luminescent source (such as ZnS) which interacts with radiation.  When a radioactive particle decays and strikes the photo luminescent material a photon is released.  This photon is multiplied in a

text: photomultiplier tube

text: which converts light into an electrical signal.  This signal is then processed and converted into a channel.  By comparing the number of counts to the energy level (typically in keV or MeV) the type of decay can be determined.

text: Subtractive color systems start with light, presumably white light. Colored inks, paints, or filters between the watchers and the light source or reflective surface subtract wavelengths from the light, giving it color.  If the incident light is other than white, our visual mechanisms are able to compensate well, but not perfectly, often giving a flawed impression of the "true" color of the surface.

text: Skyglow (or sky glow) is the diffuse luminance of the night sky, apart from discrete light sources such as the moon and visible individual stars. It is a commonly noticed aspect of light pollution.  Although usually referring to sky luminance arising from the use of artificial lighting, skyglow can also refer to all diffuse sources of night sky luminance, including artificial as well as natural sources of diffuse nighttime light like the zodiacal light, starlight, and airglow.

text: Skyglow (or sky glow) is the diffuse

text: luminance

text: of the night sky, apart from discrete light sources such as the moon and visible individual stars. It is a commonly noticed aspect of

text: light pollution

text: .  Although usually referring to sky luminance arising from the use of artificial lighting, skyglow can also refer to all diffuse sources of night sky luminance, including artificial as well as natural sources of diffuse nighttime light like the

text: zodiacal light

text: starlight

text: , and

text: airglow

text: Some skylights have expensive glazing that partially reduces summer solar heat gain, while still allowing some visible light transmission. However, if visible light can pass through it, so can some radiant heat gain (they are both electromagnetic radiation waves).

text: Some skylights have expensive glazing that partially reduces summer solar heat gain, while still allowing some visible light transmission. However, if visible light can pass through it, so can some radiant heat gain (they are both

text: electromagnetic radiation

text: waves).

text: In cases where incandescent light is in use, but a high colour temperature is required, a technique called "colour temperature correction" may be used. This involves placing a "CT" light filter in front of a light source. To the naked eye this type of filter appears blue, but when put in front of an amber shifted light source it counteracts the dominant amber colours to produce a more white light through a process known as subtractive mixing.

text: In cases where incandescent light is in use, but a high colour temperature is required, a technique called "colour temperature correction" may be used. This involves placing a "CT" light filter in front of a light source. To the

text: naked eye

text: this type of filter appears

text: blue

text: , but when put in front of an amber shifted light source it counteracts the dominant amber colours to produce a more

text: white light

text: through a process known as

text: subtractive mixing

text: Most theatrical lamps are tungsten-halogen (or quartz-halogen), an improvement on the original incandescent design that used halogen gas instead of an inert gas. Fluorescent lights are rarely used other than as work lights (see below). Although they are far more efficient, they cannot be dimmed (run at less than full power) without using specialized dimmers, cannot dim to very low levels, do not produce light from a single point or easily concentrated area, and have a warm-up period during which they emit no light or do so intermittently. High-intensity discharge lamps (or HID lamps) are now common where a very bright light output is required, for example in large follow spots, HMI (hydrargyrum medium-arc iodide) floods, and modern automated fixtures. Because these types of lamps cannot be electrically dimmed, dimming is done by mechanical dousers or shutters that physically block portions of the lamp to decrease output. Some specially-designed fittings now use light-emitting diodes (LEDs) as a light source. LEDs are ideal where an intense but unfocused light source is required, such as for lighting a cyclorama.

text: Most theatrical

text: lamps

text: are

text: tungsten-halogen

text: (or quartz-halogen), an improvement on the original

text: incandescent

text: design that used halogen gas instead of an inert gas.

text: Fluorescent

text: lights are rarely used other than as work lights (see below). Although they are far more efficient, they cannot be

text: dimmed

text: (run at less than full power) without using specialized dimmers, cannot dim to very low levels, do not produce light from a single point or easily concentrated area, and have a warm-up period during which they emit no light or do so intermittently.

text: High-intensity discharge lamp

text: s (or HID lamps) are now common where a very bright light output is required, for example in large

text: follow spot

text: s, HMI (

text: hydrargyrum medium-arc iodide

text: ) floods, and modern

text: automated fixtures

text: . Because these types of lamps cannot be electrically dimmed, dimming is done by mechanical dousers or shutters that physically block portions of the lamp to decrease output. Some specially-designed fittings now use

text: light-emitting diodes

text: (LEDs) as a light source. LEDs are ideal where an intense but unfocused light source is required, such as for lighting a cyclorama.

text: 14 December 2009, Neon Highwire digitally released their debut EP titled Luminescence to mostly positive reviews. The release was self recorded and mastered at The Exchange by Simon Davey.  It was physically released on 20 January 2010.

text: 14 December 2009, Neon Highwire digitally released their debut EP titled

text: Luminescence

text: to mostly positive reviews. The release was self recorded and mastered at

text: The Exchange

text: by

text: Simon Davey

text: .  It was physically released on 20 January 2010.

text: Measuring the effect of sky glow on a global scale is a complex procedure. The natural atmosphere is not completely dark, even in the absence of terrestrial sources of light and illumination from the Moon. This is caused by two main sources: airglow and scattered light.

text: After the initial exposure, excited electrons in the phosphor material remain 'trapped' in 'colour centres' ("F-centers") in the crystal lattice until stimulated by the second illumination. For example, Fuji's photostimulable phosphor is deposited on a flexible polyester film support with grain size about 5 micrometers, and is described as "barium fluorobromide containing a trace amount of bivalent europium as a luminescence center". Europium is a divalent cation that replaces barium to create a solid solution. When Eu ions are struck by ionizing radiation, they lose an additional electron to become Eu ions. These electrons enter the conduction band of the crystal and become trapped in the bromine ion empty lattice of the crystal. This metastable state is higher in energy than the original condition, so a lower-frequency light source that is insufficient in energy to create more Eu ions can return the trapped electrons to the conduction band. As these mobilized electrons encounter Eu ions, they release a blue-violet 400 nm luminescence.  This light is produced in proportion to the number of trapped electrons, and thus in proportion to the original X-ray signal.  It can be collected (often by a photomultiplier tube), enabling the resulting signal to be converted into a digital image.

text: After the initial exposure, excited electrons in the

text: phosphor

text: material remain 'trapped' in 'colour centres' ("F-centers") in the

text: crystal

text: lattice

text: until stimulated by the second illumination. For example, Fuji's photostimulable phosphor is deposited on a flexible polyester film support with grain size about 5

text: micrometers

text: , and is described as "

text: barium fluorobromide

text: containing a trace amount of bivalent

text: europium

text: as a luminescence center". Europium is a

text: divalent cation

text: that replaces barium to create a

text: solid solution

text: . When Eu ions are struck by ionizing radiation, they lose an additional electron to become Eu ions. These electrons enter the

text: conduction band

text: of the crystal and become trapped in the bromine ion empty lattice of the crystal. This

text: metastable state

text: is higher in energy than the original condition, so a lower-frequency light source that is insufficient in energy to create more Eu ions can return the trapped electrons to the conduction band. As these mobilized electrons encounter Eu ions, they release a blue-violet 400 nm luminescence.  This light is produced in proportion to the number of trapped electrons, and thus in proportion to the original X-ray signal.  It can be collected (often by a

text: photomultiplier tube

text: ), enabling the resulting signal to be converted into a

text: digital image

text: Several of his ongoing projects focus on problems arising in the area of modern semiconductor quantum optics, microcavities, and laser theory.In this field, Stephan W. Koch and his coworkers have concentrated on explaining how the quantum features of light can be described in connection with semiconductors. The novelty and difficulty of this research stems from determining and controlling many-body and quantum-optical features simultaneously. The first step toward this direction emerged in the form of the semiconductor luminescence equations(abbreviated as SLEs); the SLEs describe the quantum physics where quantum fluctuations of light initiate incoherent light emission from spontaneous recombination of Coulomb-coupled electron–hole pairs. The SLEs not only set the standard in describing quantum-light emission in semiconductors but they are also ideally suited for modeling quantum-light sources and filters based onsemiconductor technology. The extensions of SLEs include resonance fluorescence and higher-order photon-correlation effects and are the basis to expand the quantum-optical spectroscopy.

text: Several of his ongoing projects focus on problems arising in the area of modern semiconductor

text: quantum optics

text: microcavities

text: , and

text: laser theory

text: .In this field, Stephan W. Koch and his coworkers have concentrated on explaining how the quantum features of light can be described in connection with semiconductors. The novelty and difficulty of this research stems from determining and controlling many-body and quantum-optical features simultaneously. The first step toward this direction emerged in the form of the

text: semiconductor luminescence equations

text: (abbreviated as SLEs); the SLEs describe the quantum physics where quantum fluctuations of light initiate

text: incoherent

text: light emission from

text: spontaneous

text: recombination of

text: Coulomb

text: -coupled electron–hole pairs. The SLEs not only set the standard in describing quantum-light emission in semiconductors but they are also ideally suited for modeling quantum-light sources and filters based onsemiconductor technology. The extensions of SLEs include

text: resonance fluorescence

text: and higher-order photon-correlation effects and are the basis to expand the

text: quantum-optical spectroscopy

text: The current light characteristic is two flashes, separated by two seconds, every 10 seconds, colored white, red or green depending on direction (Fl.(2)W.R.G. 10s). White, visible for , is shown at 267°30′-281°, 288°30′-000° and 135°-252°. Green, visible for , is shown at 252°30′-267°30′ and 000°-135°. Red, visible for , is shown at the small middle sector, 281°-288°30′.The apparatus is a Chance Brothers 400 mm focal length Fresnel lens. The light source is a solar powered 12 Volt 35 Watt Halogen lamp and the intensity is  3,700 cd for the white light and 700 cd for the red and green ones.

text: The current

text: light characteristic

text: is two flashes, separated by two seconds, every 10 seconds, colored white, red or green depending on direction (Fl.(2)W.R.G. 10s). White, visible for , is shown at 267°30′-281°, 288°30′-000° and 135°-252°. Green, visible for , is shown at 252°30′-267°30′ and 000°-135°. Red, visible for , is shown at the small middle sector, 281°-288°30′.The apparatus is a

text: Chance Brothers

text: 400 mm

text: focal length

text: Fresnel lens

text: . The light source is a

text: solar powered

text: Volt

text: Watt

text: Halogen lamp

text: and the intensity is  3,700

text: cd

text: for the white light and 700 cd for the red and green ones.

text: Because damage from visible light and ultraviolet radiation is cumulative and irreversible, collections storage spaces tend to have few ambient light sources, such as windows, and often have lighting installed in multiple zones controlled by different switches, so that all of the lights do not have to be turned on when only a small area of the storage space is actively being used. LED or UV-filtered fluorescent bulbs are generally recommended, as they save energy compared to incandescent bulbs, while quartz and halogen bulbs emit high levels of UV and infrared radiation as well as a significant amount of heat, which can cause increased deterioration of objects in the space.

text: Illuminations is an incompleted suite of prose poems by the French poet Arthur Rimbaud, first published partially in , a Paris literary review, in May–June 1886. The texts were reprinted in book form in October 1886 by Les publications de La Vogue under the title Les Illuminations proposed by the poet Paul Verlaine, Rimbaud's former lover. In his preface, Verlaine explained that the title was based on the English word illuminations, in the sense of coloured plates, and a sub-title that Rimbaud had already given the work. Verlaine dated its composition between 1873 and 1875.

text: Illuminations is an incompleted suite of prose poems by the French poet

text: Arthur Rimbaud

text: , first published partially in , a Paris literary review, in May–June 1886. The texts were reprinted in book form in October 1886 by Les publications de La Vogue under the title Les Illuminations proposed by the poet

text: Paul Verlaine

text: , Rimbaud's former lover. In his preface, Verlaine explained that the title was based on the English word illuminations, in the sense of coloured plates, and a sub-title that Rimbaud had already given the work. Verlaine dated its composition between 1873 and 1875.

text: If there is more than one light source, there will be several shadows, with the overlapping parts darker, and various combinations of brightnesses or even colors. The more diffuse the lighting is, the softer and more indistinct the shadow outlines become, until they disappear. The lighting of an overcast sky produces few visible shadows.

text: If there is more than one light source, there will be several shadows, with the overlapping parts darker, and various combinations of brightnesses or even colors. The more

text: diffuse

text: the lighting is, the softer and more indistinct the shadow outlines become, until they disappear. The lighting of an overcast sky produces few visible shadows.

text: Early instances of forced perspective used in low-budget motion pictures showed objects that were clearly different from their surroundings: often blurred or at a different light level. The principal cause of this was geometric. Light from a point source travels in a spherical wave, decreasing in intensity (or illuminance) as the inverse square of the distance travelled. This means that a light source must be four times as bright to produce the same illuminance at an object twice as far away. Thus to create the illusion of a distant object being at the same distance as a near object and scaled accordingly, much more light is required. When shooting with forced perspective, it's important to have the aperture stopped down sufficiently to achieve proper DOF (depth of field), so that the foreground object and background are both sharp.

text: Early instances of forced perspective used in low-budget motion pictures showed objects that were clearly different from their surroundings: often blurred or at a different light level. The principal cause of this was geometric. Light from a

text: point source

text: travels in a spherical wave, decreasing in intensity (or

text: illuminance

text: ) as the

text: inverse square

text: of the distance travelled. This means that a light source must be four times as bright to produce the same illuminance at an object twice as far away. Thus to create the illusion of a distant object being at the same distance as a near object and scaled accordingly, much more light is required. When shooting with forced perspective, it's important to have the aperture stopped down sufficiently to achieve proper DOF (depth of field), so that the foreground object and background are both sharp.

text: In its 21st year in 2008 it was gradually converted to LED lights from traditional incandescent lights out of respect for the environment. This effort aimed to reduce operating costs allowing the festival operators to expand the magnitude of the festival.

text: In its 21st year in 2008 it was gradually converted to

text: LED lights

text: from traditional

text: incandescent light

text: s out of respect for the environment. This effort aimed to reduce operating costs allowing the festival operators to expand the magnitude of the festival.

text: It was not until the development of the bialkali antimonide photocathodes (potassium-cesium-antimony and sodium-potassium-antimony) discovered by A.H. Sommer and his later multialkali photocathode (sodium-potassium-antimony-cesium) S20 photocathode discovered in 1956 by accident, that the tubes had both suitable infra-red sensitivity and visible spectrum amplification to be useful militarily. The S20 photocathode has a sensitivity of around 150 to 200 µA/lm. The additional sensitivity made these tubes usable with limited light, such as moonlight, while still being suitable for use with low-level infrared illumination.

text: It was not until the development of the bialkali antimonide photocathodes (

text: potassium

text: cesium

text: -antimony and

text: sodium

text: -potassium-antimony) discovered by A.H. Sommer and his later multialkali photocathode (sodium-potassium-antimony-cesium) S20 photocathode discovered in 1956 by accident, that the tubes had both suitable infra-red sensitivity and visible spectrum amplification to be useful militarily. The S20 photocathode has a sensitivity of around 150 to 200 µA/lm. The additional sensitivity made these tubes usable with limited light, such as moonlight, while still being suitable for use with low-level infrared illumination.

text: The common fluorescent lamp relies on fluorescence. Inside the glass tube is a partial vacuum and a small amount of mercury. An electric discharge in the tube causes the mercury atoms to emit mostly ultraviolet light. The tube is lined with a coating of a fluorescent material, called the phosphor, which absorbs the ultraviolet and re-emits visible light. Fluorescent lighting is more energy-efficient than incandescent lighting elements. However, the uneven spectrum of traditional fluorescent lamps may cause certain colors to appear different than when illuminated by incandescent light or daylight. The mercury vapor emission spectrum is dominated by a short-wave UV line at 254 nm (which provides most of the energy to the phosphors), accompanied by visible light emission at 436 nm (blue), 546 nm (green) and 579 nm (yellow-orange). These three lines can be observed superimposed on the white continuum using a hand spectroscope, for light emitted by the usual white fluorescent tubes. These same visible lines, accompanied by the emission lines of trivalent europium and trivalent terbium, and further accompanied by the emission continuum of divalent europium in the blue region, comprise the more discontinuous light emission of the modern trichromatic phosphor systems used in many compact fluorescent lamp and traditional lamps where better color rendition is a goal.

text: The common

text: fluorescent lamp

text: relies on fluorescence. Inside the

text: glass

text: tube is a partial vacuum and a small amount of

text: mercury

text: . An electric discharge in the tube causes the mercury atoms to emit mostly ultraviolet light. The tube is lined with a coating of a fluorescent material, called the

text: phosphor

text: , which absorbs the ultraviolet and re-emits visible light. Fluorescent

text: lighting

text: is more energy-efficient than

text: incandescent

text: lighting elements. However, the uneven

text: spectrum

text: of traditional fluorescent lamps may cause certain colors to appear different than when illuminated by incandescent light or

text: daylight

text: . The mercury vapor emission spectrum is dominated by a short-wave UV line at 254 nm (which provides most of the energy to the phosphors), accompanied by visible light emission at 436 nm (blue), 546 nm (green) and 579 nm (yellow-orange). These three lines can be observed superimposed on the white continuum using a hand spectroscope, for light emitted by the usual white fluorescent tubes. These same visible lines, accompanied by the emission lines of trivalent europium and trivalent terbium, and further accompanied by the emission continuum of divalent europium in the blue region, comprise the more discontinuous light emission of the modern trichromatic phosphor systems used in many

text: compact fluorescent lamp

text: and traditional lamps where better color rendition is a goal.

text: The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm. In terms of frequency, this corresponds to a band in the vicinity of 430–770 THz.

text: The visible spectrum is the portion of the

text: electromagnetic spectrum

text: that is

text: visible

text: to the

text: human eye

text: Electromagnetic radiation

text: in this range of

text: wavelength

text: s is called visible light or simply

text: light

text: . A typical human eye will respond to wavelengths from about

text: 390 to 700 nm

text: . In terms of frequency, this corresponds to a band in the vicinity of 430–770

text: THz

text: Many flowering plants reflect as much light as possible within the range of visible wavelengths of the pollinator the plant intends to attract. Flowers that reflect the full range of visible light are generally perceived as white by a human observer. An important feature of white flowers is that they reflect equally across the visible spectrum. While many flowering plants use white to attract pollinators, the use of color is also widespread (even within the same species). Color allows a flowering plant to be more specific about the pollinator it seeks to attract. The color model used by human color reproduction technology (CMYK) relies on the modulation of pigments that divide the spectrum into broad areas of absorption. Flowering plants by contrast are able to shift the transition point wavelength between absorption and reflection. If it is assumed that the visual systems of most pollinators view the visible spectrum as circular then it may be said that flowering plants produce color by absorbing the light in one region of the spectrum and reflecting the light in the other region. With CMYK, color is produced as a function of the amplitude of the broad regions of absorption. Flowering plants by contrast produce color by modifying the frequency (or rather wavelength) of the light reflected. Most flowers absorb light in the blue to yellow region of the spectrum and reflect light from the green to red region of the spectrum. For many species of flowering plant, it is the transition point that characterizes the color that they produce. Color may be modulated by shifting the transition point between absorption and reflection and in this way a flowering plant may specify which pollinator it seeks to attract.

text: Many flowering plants reflect as much light as possible within the range of visible wavelengths of the pollinator the plant intends to attract. Flowers that reflect the full range of visible light are generally perceived as

text: white

text: by a human observer. An important feature of white flowers is that they reflect equally across the visible spectrum. While many flowering plants use white to attract pollinators, the use of color is also widespread (even within the same species). Color allows a flowering plant to be more specific about the pollinator it seeks to attract. The color model used by human color reproduction technology (

text: CMYK

text: ) relies on the modulation of pigments that divide the spectrum into broad areas of absorption. Flowering plants by contrast are able to shift the transition point wavelength between absorption and reflection. If it is assumed that the visual systems of most pollinators view the visible spectrum as

text: circular

text: then it may be said that flowering plants produce color by absorbing the light in one region of the spectrum and reflecting the light in the other region. With CMYK, color is produced as a function of the amplitude of the broad regions of absorption. Flowering plants by contrast produce color by modifying the frequency (or rather wavelength) of the light reflected. Most flowers absorb light in the blue to yellow region of the spectrum and reflect light from the green to red region of the spectrum. For many species of flowering plant, it is the transition point that characterizes the color that they produce. Color may be modulated by shifting the transition point between absorption and reflection and in this way a flowering plant may specify which pollinator it seeks to attract.

text: The accreditation of this work to Rembrandt was never disputed until Gerson's rejection solely based on stylistic grounds. The Rembrandt Research Project came into being in order to confirm or deny such claims of rejection or attribution by using forensic and historical evidence. According to Ernst van de Wetering, who was on Gerson's team in 1968, he still shares their original concerns about the painting, but the attribution to Rembrandt can be made with much more certainty today based both on historical grounds and x-ray evidence. Rembrandt painted the self-portrait during the period he was playing with light and shadow around the eyes; the beret hides his eyes and his nose and cheek become the light source, with a light reflection visible on the lower eyelid.During the same period, Rembrandt made many portraits and even self-portraits with feathered hats, and he is known for various sketches and portraits with light reflecting on lower eyelids.

text: The accreditation of this work to Rembrandt was never disputed until Gerson's rejection solely based on stylistic grounds. The

text: Rembrandt Research Project

text: came into being in order to confirm or deny such claims of rejection or attribution by using forensic and historical evidence. According to Ernst van de Wetering, who was on Gerson's team in 1968, he still shares their original concerns about the painting, but the attribution to Rembrandt can be made with much more certainty today based both on historical grounds and x-ray evidence. Rembrandt painted the self-portrait during the period he was playing with light and shadow around the eyes; the beret hides his eyes and his nose and cheek become the light source, with a light reflection visible on the lower eyelid.During the same period, Rembrandt made many portraits and even self-portraits with feathered hats, and he is known for various sketches and portraits with light reflecting on lower eyelids.

text: The human eye is not equally sensitive to all wavelengths of visible light. Photometry attempts to account for this by weighing the measured power at each wavelength with a factor that represents how sensitive the eye is at that wavelength. The standardized model of the eye's response to light as a function of wavelength is given by the luminosity function. The eye has different responses as a function of wavelength when it is adapted to light conditions (photopic vision) and dark conditions (scotopic vision). Photometry is typically based on the eye's photopic response, and so photometric measurements may not accurately indicate the perceived brightness of sources in dim lighting conditions where colors are not discernible, such as under just moonlight or starlight. Photopic vision is characteristic of the eye's response at luminance levels over three candela per square metre. Scotopic vision occurs below 2 × 10  cd/m. Mesopic vision occurs between these limits and is not well characterised for spectral response.

text: The

text: human eye

text: is not equally sensitive to all

text: wavelength

text: s of

text: visible light

text: . Photometry attempts to account for this by weighing the measured power at each wavelength with a factor that represents how sensitive the eye is at that wavelength. The standardized model of the eye's response to light as a function of wavelength is given by the luminosity function. The eye has different responses as a function of wavelength when it is adapted to light conditions (

text: photopic vision

text: ) and dark conditions (

text: scotopic vision

text: ). Photometry is typically based on the eye's photopic response, and so photometric measurements may not accurately indicate the perceived brightness of sources in dim lighting conditions where colors are not discernible, such as under just moonlight or starlight. Photopic vision is characteristic of the eye's response at luminance levels over three candela per square metre. Scotopic vision occurs below 2 × 10  cd/m.

text: Mesopic vision

text: occurs between these limits and is not well characterised for spectral response.

text: In lighting design, backlighting is the process of illuminating the subject from the back. In other words, the lighting instrument and the viewer face each other, with the subject in between. This creates a glowing effect on the edges of the subject, while other areas are darker. The backlight can be a natural or artificial source of light. When artificial, the back light is usually placed directly behind the subject in a 4-point lighting setup. A back light, which lights foreground elements from the rear, is not to be confused with a background light, which lights background elements (such as scenery).

text: In

text: lighting design

text: , backlighting is the process of

text: illuminating

text: the subject from the back. In other words, the

text: lighting instrument

text: and the

text: viewer

text: face each other, with the subject in between. This creates a

text: glowing

text: effect on the edges of the subject, while other areas are darker. The backlight can be a natural or artificial source of light. When artificial, the back light is usually placed directly behind the subject in a

text: 4-point lighting setup

text: . A back light, which lights foreground elements from the rear, is not to be confused with a

text: background light

text: , which lights background elements (such as scenery).

text: Underglow (2005-2006): the project consisted of illuminations of a number of drains in the vicinity of Guildhall Yard, King Street and Queen Street in the City of London, which were visible from dusk to dawn during the winter of 2005-06. The project was commissioned by the City of London Corporation and Modus Operandi as part of the 'Light Up Queen Street' programme.

text: Underglow (2005-2006): the project consisted of illuminations of a number of

text: drains

text: in the vicinity of

text: Guildhall Yard

text: King Street and Queen Street

text: in the

text: City of London

text: , which were visible from dusk to dawn during the winter of 2005-06. The project was commissioned by the

text: City of London Corporation

text: and Modus Operandi as part of the 'Light Up Queen Street' programme.

text: A proctoscope is a hollow, tube-like speculum that is used for visual inspection of the rectum. Both disposable and non-disposable proctoscopes are available for use. Out of these, the non-disposable Kelly's rectal speculum, named after the American gynecologist Howard Atwood Kelly, is the most commonly used speculum for proctoscopy. Some proctoscopes have a light source for better visibility. The proctoscope is inserted into the anal canal with the patient in Sims' position. Fibre optic proctoscopes are now available which cause less discomfort to the patient.

text: A proctoscope is a hollow, tube-like

text: speculum

text: that is used for visual inspection of the rectum. Both disposable and non-disposable proctoscopes are available for use. Out of these, the non-disposable Kelly's rectal speculum, named after the American gynecologist

text: Howard Atwood Kelly

text: , is the most commonly used speculum for proctoscopy. Some proctoscopes have a light source for better visibility. The proctoscope is inserted into the

text: anal canal

text: with the patient in

text: Sims' position

text: . Fibre optic proctoscopes are now available which cause less discomfort to the patient.

text: A hot mirror is a specialized dielectric mirror, a dichroic filter, often employed to protect optical systems by reflecting infrared light back into a light source, while allowing visible light to pass. Hot mirrors can be designed to be inserted into the optical system at an incidence angle varying between zero and 45 degrees, and are useful in a variety of applications where the buildup of waste heat can damage components or adversely affect spectral characteristics of the illumination source. Wavelengths reflected by an infrared hot mirror range from about 750 to 1250 nanometers. By transmitting visible light wavelengths while reflecting infrared, hot mirrors can also serve as dichromatic beam splitters for specialized applications in fluorescence microscopy or optical eye tracking.

text: A hot mirror is a specialized

text: dielectric mirror

text: , a

text: dichroic filter

text: , often employed to protect optical systems by reflecting

text: infrared light

text: back into a light source, while allowing

text: visible light

text: to pass. Hot mirrors can be designed to be inserted into the optical system at an

text: incidence angle

text: varying between zero and 45 degrees, and are useful in a variety of applications where the buildup of

text: waste heat

text: can damage components or adversely affect spectral characteristics of the illumination source.

text: Wavelength

text: s reflected by an infrared hot mirror range from about 750 to 1250

text: nanometer

text: s. By transmitting visible light wavelengths while reflecting infrared, hot mirrors can also serve as dichromatic

text: beam splitter

text: s for specialized applications in

text: fluorescence microscopy

text: or optical eye tracking.

text: A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent light bulb; some types fit into light fixtures designed for incandescent bulbs. The lamps use a tube which is curved or folded to fit into the space of an incandescent bulb, and a compact electronic ballast in the base of the lamp.

text: A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is a

text: fluorescent lamp

text: designed to replace an

text: incandescent light bulb

text: ; some types fit into

text: light fixture

text: s designed for incandescent bulbs. The lamps use a tube which is curved or folded to fit into the space of an incandescent bulb, and a compact

text: electronic ballast

text: in the base of the lamp.

text: Much of the low luminosity of a red dwarf falls in the infrared part of the electromagnetic spectrum, with lower energy than the visible light in which the Sun peaks. As a result, photosynthesis on a red dwarf planet would require additional photons to achieve excitation potentials comparable to those needed in Earth photosynthesis for electron transfers, due to the lower average energy level of near-infrared photons compared to visible. Having to adapt to a far wider spectrum to gain the maximum amount of energy, foliage on a habitable red dwarf planet would probably appear black if viewed in visible light.

text: Much of the low luminosity of a red dwarf falls in the infrared part of the electromagnetic spectrum, with lower energy than the visible light in which the Sun peaks. As a result,

text: photosynthesis

text: on a red dwarf planet would require additional photons to achieve excitation potentials comparable to those needed in Earth photosynthesis for electron transfers, due to the lower average energy level of near-infrared photons compared to visible. Having to adapt to a far wider spectrum to gain the maximum amount of energy, foliage on a habitable red dwarf planet would probably appear black if viewed in visible light.

text: Fall prevention is thus an important consideration in designing homes for the elderly, and one of the most critical parts of that design process is supplying strong and effective lighting. Thus, when switched on, lights should react instantaneously, so the user is not surprised by a hidden obstacle as he or she moves into a kitchen or bathroom, for example. In such a case, incandescent light bulbs are preferred over fluorescent lighting, because they react instantaneously while a CFL takes time to warm up and become bright. Incandescent light bulbs also offer much greater illuminance than many other light sources, are relatively low cost and easy to install. Higher lighting levels enable users to see potential hazards before they need to take avoiding action, and so negotiate them safely and easily. Excellent colour rendering (as measured by the Colour rendering index) by such incandescent light also helps users identify  colours correctly. Halogen bulbs are also available for greater efficiency, as are rough service bulbs to avoid discriminatory regulations, especially in the EU. No doubt LED lights will become an alternative source of high quality lighting in the future, but in 2013 they remain expensive for domestic use. Rough service bulbs are available in sizes up to 200 watt in all varieties of fittings. Although lifetime is generally lower than for CFLs, they are replaced easily.

text: Fall prevention

text: is thus an important consideration in designing homes for the elderly, and one of the most critical parts of that design process is supplying strong and effective lighting. Thus, when switched on, lights should react instantaneously, so the user is not surprised by a hidden obstacle as he or she moves into a kitchen or bathroom, for example. In such a case,

text: incandescent light bulb

text: s are preferred over

text: fluorescent lighting

text: , because they react instantaneously while a

text: CFL

text: takes time to warm up and become bright.

text: Incandescent light bulbs

text: also offer much greater

text: illuminance

text: than many other light sources, are relatively low cost and easy to install. Higher lighting levels enable users to see potential hazards before they need to take avoiding action, and so negotiate them safely and easily. Excellent

text: colour

text: rendering (as measured by the

text: Colour rendering index

text: ) by such incandescent light also helps users identify  colours correctly.

text: Halogen bulb

text: s are also available for greater efficiency, as are

text: rough service

text: bulbs to avoid discriminatory regulations, especially in the EU. No doubt

text: LED lights

text: will become an alternative source of high quality lighting in the future, but in 2013 they remain expensive for domestic use. Rough service bulbs are available in sizes up to 200 watt in all varieties of fittings. Although lifetime is generally lower than for CFLs, they are replaced easily.

text: Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold-body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions, or stress on a crystal. This distinguishes luminescence from incandescence, which is light emitted by a substance as a result of heating. Historically, radioactivity was thought of as a form of "radio-luminescence", although it is today considered to be separate since it involves more than electromagnetic radiation. The term 'luminescence' was introduced in 1888 by Eilhard Wiedemann.

text: Luminescence is emission of

text: light

text: by a substance not resulting from heat; it is thus a form of cold-body

text: radiation

text: . It can be caused by

text: chemical reaction

text: s,

text: electrical energy

text: , subatomic motions, or

text: stress on a crystal

text: . This distinguishes luminescence from

text: incandescence

text: , which is light emitted by a substance as a result of heating. Historically,

text: radioactivity

text: was thought of as a form of "radio-luminescence", although it is today considered to be separate since it involves more than electromagnetic radiation. The term 'luminescence' was introduced in 1888 by

text: Eilhard Wiedemann

text: Distorting, obscuring or destroying the projected light by using a surface that is not flat or specifically designed to do so, or by overpowering the light with an alternative source such as theatre lights. This allows for choreography to reveal the image with the greatest, most appropriate dramatic effect, as the image is only visible when interacted with.

text: An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated to such a high temperature that it glows with visible light (incandescence). The filament, heated by passing an electric current through it, is protected from oxidation with a glass or quartz bulb that is filled with inert gas or evacuated. In a halogen lamp, filament evaporation is prevented by a chemical process that redeposits metal vapor onto the filament, extending its life. The light bulb is supplied with electric current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections.

text: An incandescent light bulb, incandescent lamp or incandescent light globe is an

text: electric light

text: with a wire

text: filament

text: heated to such a high temperature that it glows with visible light (

text: incandescence

text: ). The filament, heated by passing an

text: electric current

text: through it, is protected from oxidation with a glass or quartz bulb that is filled with inert gas or

text: evacuated

text: . In a

text: halogen lamp

text: , filament evaporation is prevented by a chemical process that redeposits metal vapor onto the filament, extending its life. The light bulb is supplied with electric current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections.

text: In cloudy climates, diffuse light from the sky is the main source of lighting. At the site planning stage, a sufficient area of sky must be made visible to give good interior lighting.

text: In cloudy

text: climate

text: s,

text: diffuse

text: light from the sky is the main source of lighting. At the site planning stage, a sufficient area of sky must be made visible to give good interior lighting.

text: Symbiotic bacteria belonging to the family Vibrionaceae are responsible for the luminescence; the strain of bacteria is apparently different in each species. The bacteria are believed to originate from the surrounding seawater and colonise the organs via external ducts. The light produced is bluish to greenish, and the host female presumably has some control over its production.

text: Symbiotic

text: bacteria

text: belonging to the family

text: Vibrionaceae

text: are responsible for the luminescence; the

text: strain

text: of bacteria is apparently different in each species. The bacteria are believed to originate from the surrounding seawater and colonise the organs via external ducts. The light produced is bluish to greenish, and the host female presumably has some control over its production.

text: Illuminant E is an equal-energy radiator; it has a constant SPD inside the visible spectrum. It is useful as a theoretical reference; an illuminant that gives equal weight to all wavelengths, presenting an even color. It also has equal CIE XYZ tristimulus values, thus its chromaticity coordinates are (x,y)=(1/3,1/3). This is by design; the XYZ color matching functions are normalized such that their integrals over the visible spectrum are the same.

text: Illuminant E is an equal-energy radiator; it has a constant SPD inside the

text: visible spectrum

text: . It is useful as a theoretical reference; an illuminant that gives equal weight to all wavelengths, presenting an even color. It also has equal

text: CIE XYZ

text: tristimulus values, thus its chromaticity coordinates are (x,y)=(1/3,1/3). This is by design; the XYZ color matching functions are normalized such that their integrals over the visible spectrum are the same.

text: Many species can see light within frequencies outside the human "visible spectrum". Bees and many other insects can detect ultraviolet light, which helps them find nectar in flowers. Plant species that depend on insect pollination may owe reproductive success to their appearance in ultraviolet light rather than how colorful they appear to humans. Birds, too, can see into the ultraviolet (300–400 nm), and some have sex-dependent markings on their plumage that are visible only in the ultraviolet range. Many animals that can see into the ultraviolet range, however, cannot see red light or any other reddish wavelengths. Bees' visible spectrum ends at about 590 nm, just before the orange wavelengths start. Birds, however, can see some red wavelengths, although not as far into the light spectrum as humans. The popular belief that the common goldfish is the only animal that can see both infrared and ultraviolet light  is incorrect, because goldfish cannot see infrared light. Similarly, dogs are often thought to be color blind but they have been shown to be sensitive to colors, though not as many as humans.

text: Many species can see light within frequencies outside the human "visible spectrum".

text: Bee

text: s and many other insects can detect ultraviolet light, which helps them find

text: nectar

text: in flowers. Plant species that depend on insect pollination may owe reproductive success to their appearance in ultraviolet light rather than how colorful they appear to humans. Birds, too, can see into the ultraviolet (300–400 nm), and some have sex-dependent markings on their plumage that are visible only in the ultraviolet range. Many animals that can see into the ultraviolet range, however, cannot see red light or any other reddish wavelengths. Bees' visible spectrum ends at about 590 nm, just before the orange wavelengths start. Birds, however, can see some red wavelengths, although not as far into the light spectrum as humans. The popular belief that the common goldfish is the only animal that can see both infrared and ultraviolet light  is incorrect, because goldfish cannot see infrared light. Similarly, dogs are often thought to be color blind but they have been shown to be sensitive to colors, though not as many as humans.

text: The powerful central light source creates a chiaroscuro effect. The light illuminating the scene has been described as "so brilliant it could only be the light of revelation". The single source of light is obscured behind the bowl on the table; some hint of a lamp glass can be seen around the side of the bowl, but David Hockney has suggested that the bowl itself may contain sulphur, giving a powerful single light source that a candle or oil lamp would not. In the earlier study a candle holder is visible, and the flame is reflected in the bowl. Hockney believes that many of the Old Masters used optical equipment to assist in their painting, and suggests that Wright may have used lenses to transfer the image to paper rather than painting directly from the scene, as he believes the pattern of shadows thrown by the lighting could have been too complicated for Wright to have captured so accurately without assistance. It may be observed, however, that the stand on which the pump is situated casts no shadow on the body of the philosopher, as it could be expected to do.

text: The powerful central light source creates a

text: chiaroscuro

text: effect. The light illuminating the scene has been described as "so brilliant it could only be the light of revelation". The single source of light is obscured behind the bowl on the table; some hint of a lamp glass can be seen around the side of the bowl, but

text: David Hockney

text: has suggested that the bowl itself may contain sulphur, giving a powerful single light source that a candle or oil lamp would not. In the earlier study a candle holder is visible, and the flame is reflected in the bowl. Hockney

text: believes

text: that many of the

text: Old Master

text: s used optical equipment to assist in their painting, and suggests that Wright may have used lenses to transfer the image to paper rather than painting directly from the scene, as he believes the pattern of shadows thrown by the lighting could have been too complicated for Wright to have captured so accurately without assistance. It may be observed, however, that the stand on which the pump is situated casts no shadow on the body of the philosopher, as it could be expected to do.

text: These components lie in this order between the light source and the specimen and control the illumination of the specimen. The collector/field lenses act to collect light from the light source and focus it at the plane of the condenser diaphragm. The condenser lens acts to project this light, without focusing it, through the sample. This illumination scheme creates two sets of conjugate image planes, one with the light source image and one with the specimen. These two sets of image planes are found at the following points:

text: Compared to other sources of illumination, such as fluorescent and incandescent bulbs, LEDs are energy efficient and increasingly inexpensive. As hard-point light sources, however, LEDs have several significant limitations in edge-lit digital displays.

text: Nothing categorically distinguishes the visible spectrum of electromagnetic radiation from invisible portions of the broader spectrum.  In this sense, color is not a property of electromagnetic radiation, but a feature of visual perception by an observer.  Furthermore, there is an arbitrary mapping between wavelengths of light in the visual spectrum and human experiences of color.  Although most people are assumed to have the same mapping, the philosopher John Locke recognized that alternatives are possible, and described one such hypothetical case with the "inverted spectrum" thought experiment.  For example, someone with an inverted spectrum might experience green while seeing 'red' (700 nm) light, and experience red while seeing 'green' (530 nm) light.  Synesthesia (or ideasthesia) provides some atypical but illuminating examples of subjective color experience triggered by input that is not even light, such as sounds or shapes.  The possibility of a clean dissociation between color experience from properties of the world reveals that color is a subjective psychological phenomenon.

text: Nothing categorically distinguishes the visible spectrum of electromagnetic radiation from invisible portions of the broader spectrum.  In this sense, color is not a property of electromagnetic radiation, but a feature of visual perception by an observer.  Furthermore, there is an arbitrary mapping between wavelengths of light in the visual spectrum and human experiences of color.  Although most people are assumed to have the same mapping, the philosopher

text: John Locke

text: recognized that alternatives are possible, and described one such hypothetical case with the "inverted spectrum" thought experiment.  For example, someone with an inverted spectrum might experience green while seeing 'red' (700 nm) light, and experience red while seeing 'green' (530 nm) light.

text: Synesthesia

text: (or

text: ideasthesia

text: ) provides some atypical but illuminating examples of subjective color experience triggered by input that is not even light, such as sounds or shapes.  The possibility of a clean dissociation between color experience from properties of the world reveals that color is a subjective psychological phenomenon.

text: [and artificial processes that emit light. This article focuses on sources that produce wavelengths from about 390 to 700 nanometers called visible light.

text: [and

text: artificial

text: processes that emit

text: light

text: . This article focuses on sources that produce wavelengths from about 390 to 700 nanometers called visible light.

text: In recent times, in many cities much larger than Williamsburg, such as Richmond, Virginia, multiple skyscrapers and other buildings are decorated with long mostly vertical strings of lights of a common theme, and are activated simultaneously in "Grand Illumination" ceremonies. Some communities, such as Norfolk, Virginia and Asheville, North Carolina, have Grand Illumination parades. In Chattanooga, Tennessee, a similar event is called the "Grand Illumination On The River."  In Oak Bluffs, Massachusetts, on Martha's Vineyard, Grand Illumination is one of the most significant events each summer, immediately preceded by a Community Sing. In the United Kingdom, the "Grand Illumination" ceremony is generally referred to as "Turning On The Lights", and occurs in virtually all towns and cities throughout the country.

text: In recent times, in many cities much larger than Williamsburg, such as

text: Richmond, Virginia

text: , multiple

text: skyscraper

text: s and other buildings are decorated with long mostly vertical strings of lights of a common theme, and are activated simultaneously in "Grand Illumination" ceremonies. Some communities, such as

text: Norfolk, Virginia

text: and

text: Asheville, North Carolina

text: , have Grand Illumination

text: parade

text: s. In

text: Chattanooga, Tennessee

text: , a similar event is called the "Grand Illumination On The River."  In

text: Oak Bluffs, Massachusetts

text: , on

text: Martha's Vineyard

text: , Grand Illumination is one of the most significant events each summer, immediately preceded by a Community Sing. In the

text: United Kingdom

text: , the "Grand Illumination" ceremony is generally referred to as "Turning On The Lights", and occurs in virtually all towns and cities throughout the country.

text: An intensity interferometer is built from two light detectors, typically either radio antenna or optical telescopes with photomultiplier tubes (PMTs), separated by some distance, called the baseline. Both detectors are pointed at the same astronomical source, and intensity measurements are then transmitted to a central correlator facility. A major advantage of intensity interferometers is that only the measured intensity observed by each detector must be sent to the central correlator facility, rather than the amplitude and phase of the signal. The intensity interferometer measures interferometric visibilities like all other astronomical interferometers. These measurements can be used to calculate the diameter and limb darkening coefficients of stars, but with intensity interferometers aperture synthesis images cannot be produced as the visibility phase information is not preserved by an intensity interferometer.

text: An intensity interferometer is built from two light detectors, typically either

text: radio antenna

text: or optical telescopes with

text: photomultiplier

text: tubes (PMTs), separated by some distance, called the baseline. Both detectors are pointed at the same astronomical source, and intensity measurements are then transmitted to a central correlator facility. A major advantage of intensity interferometers is that only the measured intensity observed by each detector must be sent to the central correlator facility, rather than the amplitude and phase of the signal. The intensity interferometer measures interferometric visibilities like all other astronomical interferometers. These measurements can be used to calculate the diameter and limb darkening coefficients of stars, but with intensity interferometers

text: aperture synthesis

text: images cannot be produced as the visibility phase information is not preserved by an intensity interferometer.

text: Infrared radiation is popularly known as "heat radiation", but light and electromagnetic waves of any frequency will heat surfaces that absorb them. Infrared light from the Sun accounts for 49% of the heating of Earth, with the rest being caused by visible light that is absorbed then re-radiated at longer wavelengths. Visible light or ultraviolet-emitting lasers can char paper and incandescently hot objects emit visible radiation. Objects at room temperature will emit radiation concentrated mostly in the 8 to 25 µm band, but this is not distinct from the emission of visible light by incandescent objects and ultraviolet by even hotter objects (see black body and Wien's displacement law).

text: Infrared radiation is popularly known as "heat radiation", but light and electromagnetic waves of any frequency will heat surfaces that absorb them. Infrared light from the Sun accounts for 49% of the heating of Earth, with the rest being caused by visible light that is absorbed then re-radiated at longer wavelengths. Visible light or

text: ultraviolet

text: -emitting

text: laser

text: s can char paper and incandescently hot objects emit visible radiation. Objects at room

text: temperature

text: will

text: emit

text: radiation

text: concentrated mostly in the 8 to 25 µm band, but this is not distinct from the emission of visible light by incandescent objects and ultraviolet by even hotter objects (see

text: black body

text: and

text: Wien's displacement law

text: Since the 1980s, thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) dating are available providing the possibility for dating the time of loess (dust) deposition, i.e. the time elapsed since the last exposure of the mineral grains to daylight. During the past decade, luminescence dating has significantly improved by new methodological improvements, especially the development of single aliquot regenerative (SAR) protocols (Murray & Wintle 2000) resulting in reliable ages (or age estimates) with an accuracy of up to 5 and 10% for the last glacial record. More recently, luminescence dating has also become a robust dating technique for penultimate and antepenultimate glacial loess (e.g. Thiel et al. 2011, Schmidt et al. 2011) allowing for a reliable correlation of loess/palaeosol sequences for at least the last two interglacial/glacial cycles throughout Europe and the Northern Hemisphere (Frechen 2011). Furthermore, the numerical dating provides the basis for quantitative loess research applying more sophisticated methods to determine and understand high-resolution proxy data, such as the palaeodust content of the atmosphere, variations of the atmospheric circulation patterns and wind systems, palaeoprecipitation and palaeotemperature.

text: Since the 1980s,

text: thermoluminescence

text: (TL),

text: optically stimulated luminescence

text: (OSL) and infrared stimulated luminescence (IRSL) dating are available providing the possibility for dating the time of loess (dust) deposition, i.e. the time elapsed since the last exposure of the mineral grains to daylight. During the past decade,

text: luminescence dating

text: has significantly improved by new methodological improvements, especially the development of single

text: aliquot

text: regenerative (SAR) protocols (Murray & Wintle 2000) resulting in reliable ages (or age estimates) with an accuracy of up to 5 and 10% for the

text: last glacial

text: record. More recently, luminescence dating has also become a robust dating technique for penultimate and antepenultimate glacial loess (e.g. Thiel et al. 2011, Schmidt et al. 2011) allowing for a reliable correlation of loess/palaeosol sequences for at least the last two interglacial/glacial cycles throughout Europe and the Northern Hemisphere (Frechen 2011). Furthermore, the numerical dating provides the basis for quantitative loess research applying more sophisticated methods to determine and understand high-resolution proxy data, such as the palaeodust content of the atmosphere, variations of the atmospheric circulation patterns and wind systems, palaeoprecipitation and palaeotemperature.

text: The Sydney Glaciarium was built on the site of the old Cyclorama, which was demolished. The ice floor was 51.82 meters (170 feet) long and 23.16 meters (76 feet) wide and the apex of the steel roof was 18.59 meters (61 feet) high when measured from the floor. The ice floor itself had a sheet of ice that was approximately 10.16cm (4 inches) thick and was transparent so that the estimated 11-13Km (7-8 miles) of piping was visible. The building was illuminated with electric lighting.

text: Bright-field microscopy is the simplest of all the optical microscopy illumination techniques. Sample illumination is transmitted (i.e., illuminated from below and observed from above) white light and contrast in the sample is caused by absorbance of some of the transmitted light in dense areas of the sample. Bright-field microscopy is the simplest of a range of techniques used for illumination of samples in light microscopes and its simplicity makes it a popular technique. The typical appearance of a bright-field microscopy image is a dark sample on a bright background, hence the name.

text: Bright-field microscopy is the simplest of all the

text: optical microscopy

text: illumination

text: techniques. Sample illumination is transmitted (i.e., illuminated from below and observed from above)

text: white light

text: and contrast in the sample is caused by

text: absorbance

text: of some of the transmitted light in dense areas of the sample. Bright-field microscopy is the simplest of a range of techniques used for illumination of samples in light microscopes and its simplicity makes it a popular technique. The typical appearance of a bright-field microscopy image is a dark sample on a bright background, hence the name.

text: The current light source is a solar powered 12 volt Halogen Lamp, with an intensity of 37,000 cd. The light characteristic shown is a white flash every five seconds (Fl.W. 5s). The light is visible for

text: The current light source is a solar powered 12

text: volt

text: Halogen Lamp

text: , with an intensity of 37,000 cd. The light characteristic shown is a white flash every five seconds (Fl.W. 5s). The light is visible for

text: Skyglow refers to the diffuse glow that can be seen over populated areas. It arises from light reflected from illuminated surfaces and from light escaping directly upward from incompletely shielded or upward-directed light fixtures, which then is scattered (redirected) by the atmosphere back toward the ground. The brightness of skyglow is affected strongly by the amount of light used, the shielding characteristics of the light fixtures, and by the color or spectral content of the light sources. Though it is commonly thought that Rayleigh scattering strongly increases the brightness of skyglow arising from white sources with strong blue and green emission, the dominant spectral effect has been shown to arise from the Purkinje effect instead. Because of the eye's increased sensitivity to blue and green light when adapted to very low luminance levels (such as those in even moderately polluted clear night skies), white light sources such as white LEDs contribute significantly more to skyglow than an equal amount of yellow light from sources such as high-pressure sodium, low-pressure sodium, or amber AlGaInP LEDs. Sky glow is of particular irritation to astronomers, as it interferes with astronomical observations, but multitudes suffer from the decreased visibility of star-filled night skies.

text: Skyglow refers to the diffuse glow that can be seen over populated areas. It arises from light reflected from illuminated surfaces and from light escaping directly upward from incompletely shielded or upward-directed light fixtures, which then is scattered (redirected) by the atmosphere back toward the ground. The brightness of skyglow is affected strongly by the amount of light used, the shielding characteristics of the light fixtures, and by the color or spectral content of the light sources. Though it is commonly thought that

text: Rayleigh scattering

text: strongly increases the brightness of skyglow arising from white sources with strong blue and green emission, the dominant spectral effect has been shown to arise from the

text: Purkinje effect

text: instead. Because of the eye's increased sensitivity to blue and green light when adapted to very low

text: luminance

text: levels (such as those in even moderately polluted clear night skies), white light sources such as white

text: LEDs

text: contribute significantly more to skyglow than an equal amount of yellow light from sources such as

text: high-pressure sodium

text: low-pressure sodium

text: , or amber

text: AlGaInP

text: LEDs. Sky glow is of particular irritation to astronomers, as it interferes with astronomical observations, but multitudes suffer from the decreased visibility of star-filled night skies.

text: An effort by the heritage society "Les amis de Thorigny" attempts to bring to light the historical importance of this naturally beautiful ancient village and to protect the important monuments such as the sloping medieval church with still visible military fortifications and which was built on the source of the Oreuse river, the beautiful gardens of the Château du Thorigny which was dismantled during the revolution, the Château de Fleurigny and the Commanderie de Launay.

text: The JWST's primary scientific mission has four key goals: to search for light from the first stars and galaxies that formed in the Universe after the Big Bang, to study the formation and evolution of galaxies, to understand the formation of stars and planetary systems and to study planetary systems and the origins of life. These goals can be accomplished more effectively by observation in near-infrared light rather than light in the visible part of the spectrum. For this reason the JWST's instruments will not measure visible or ultraviolet light like the Hubble Telescope, but will have a much greater capacity to perform infrared astronomy. The JWST will be sensitive to a range of wavelengths from 0.6 (orange light) to 28 micrometers (deep infrared radiation at about ).

text: The JWST's primary scientific mission has four key goals: to search for

text: light

text: from the first

text: star

text: s and

text: galaxies

text: that formed in the

text: Universe

text: after the

text: Big Bang

text: , to study the

text: formation and evolution of galaxies

text: , to understand the

text: formation of stars

text: and

text: planetary systems

text: and to study

text: planetary system

text: s and the

text: origins of life

text: . These goals can be accomplished more effectively by observation in near-infrared light rather than light in the visible part of the spectrum. For this reason the JWST's instruments will not measure visible or ultraviolet light like the Hubble Telescope, but will have a much greater capacity to perform

text: infrared astronomy

text: . The JWST will be sensitive to a range of wavelengths from 0.6 (orange light) to 28

text: micrometers

text: (deep infrared radiation at about ).

text: Displaying the amazing detail and richness of a text, the addition of illumination was never an afterthought. The inclusion of illumination is twofold, it added value to the work, but more importantly it provides pictures for the illiterate members of society to "make the reading seem more vivid and perhaps more credible.”

text: Luminescence occurs in some minerals when they are exposed to low-powered sources of ultraviolet or infrared electromagnetic radiation (for example, portable UV lamps), at atmospheric pressure and atmospheric temperatures. This property of these minerals can be used during the process of mineral identification at rock outcrops in the field, or in the laboratory.

text: Luminescence occurs in some

text: mineral

text: s when they are exposed to low-powered sources of

text: ultraviolet

text: or

text: infrared

text: electromagnetic radiation

text: (for example,

text: portable UV lamp

text: s), at

text: atmospheric pressure

text: and atmospheric temperatures. This property of these minerals can be used during the process of mineral identification at rock

text: outcrop

text: s in the

text: field

text: , or in the laboratory.

text: Cars are typically fitted with multiple types of lights. These include headlights, which are used to illuminate the way ahead and make the car visible to other users, so that the vehicle can be used at night; in some jurisdictions, daytime running lights; red brake lights to indicate when the brakes are applied; amber turn signal lights to indicate the turn intentions of the driver; white-coloured reverse lights to illuminate the area behind the car (and indicate that the driver will be or is reversing); and on some vehicles, additional lights (e.g., side marker lights) to increase the visibility of the car. Interior lights on the ceiling of the car are usually fitted for the driver and passengers. Some vehicles also have a trunk light and, more rarely, an engine compartment light.

text: Cars are typically fitted with multiple types of lights. These include

text: headlight

text: s, which are used to illuminate the way ahead and make the car visible to other users, so that the vehicle can be used at night; in some jurisdictions,

text: daytime running lights

text: ; red brake lights to indicate when the brakes are applied; amber turn signal lights to indicate the turn intentions of the driver; white-coloured reverse lights to illuminate the area behind the car (and indicate that the driver will be or is reversing); and on some vehicles, additional lights (e.g., side marker lights) to increase the visibility of the car. Interior lights on the ceiling of the car are usually fitted for the driver and passengers. Some vehicles also have a trunk light and, more rarely, an engine compartment light.

text: λ Orionis (also known as Meissa or Heka) is the star representing the head of Orion and can be found to the North of the quadrangle defined by the stars Betelgeuse, Bellatrix, Rigel and Saiph. This star can be found at the centre of open cluster Collinder 69 composed of fourth and fifth-magnitude young hot stars, visible to the naked eye.  It can be resolved with a pair of binoculars. The star phi2 Orionis , an orange giant which can be seen in the southeastern sector of the cluster, is not part of this region, although it might appear to be so due to projection effects. Its distance from the Sun is, in fact, only 116 light-years, as opposed to over 1400 light-years for the cluster itself and its associated nebula. Conversely, the nebula itself is not visible with binoculars or small amateur telescopes. It becomes clearly visible in long exposure photographs.

text: λ Orionis

text: (also known as Meissa or Heka) is the

text: star

text: representing the head of

text: Orion

text: and can be found to the

text: North

text: of the quadrangle defined by the stars

text: Betelgeuse

text: Bellatrix

text: Rigel

text: and

text: Saiph

text: . This star can be found at the centre of open cluster

text: Collinder 69

text: composed of fourth and fifth-magnitude young hot stars, visible to the naked eye.  It can be resolved with a pair of

text: binoculars

text: . The star

text: phi2 Orionis

text: , an

text: orange giant

text: which can be seen in the southeastern sector of the cluster, is not part of this region, although it might appear to be so due to projection effects. Its distance from the

text: Sun

text: is, in fact, only 116

text: light-years

text: , as opposed to over 1400

text: light-years

text: for the cluster itself and its associated nebula. Conversely, the nebula itself is not visible with

text: binoculars

text: or small amateur

text: telescopes

text: . It becomes clearly visible in long exposure

text: photographs

text: In Europe, lighting of public squares in major cities was more important than in America, primarily because American cities had fewer squares. Paris, in particular, reinforced its reputation as the City of Lights by illuminating the Place de l'Opéra and the Avenue de l'Opéra as early as 1878, and in 1912 Edith Wharton wrote home in distress that the city landmarks were lighted at night, "torn from their mystery by the vulgar intrusion of floodlighting." Conversely, since European cities had hardly any skyscrapers, lighting from within the building or on its facade dominated the use of light in modern architecture to an extent that it did not in America. Some buildings used glass illuminated from within; for example Franz Jourdain's 1907 extension to the Samaritaine department store in Paris, with glass domes, and Erich Mendelsohn's 1928 Petersdorff Department Store in Breslau, with ribbon windows illuminated by over-mounted neon lighting reflected out into the street by white curtains. The emphasis on bright, flat surfaces to simplify illumination helped to spread the architectural vocabulary of modernism. Architects themselves drew attention to and embraced the greater importance of lighted advertising, rather than the American approach of floodlighting a skyscraper like "a gleaming holy grail" or "the dream castle of Valhalla" and ignoring the possibilities for lettering of the "gigantic, widely visible wall areas". Häring went so far as to welcome "the destruction of architecture" by advertising:

text: In Europe, lighting of public squares in major cities was more important than in America, primarily because American cities had fewer squares. Paris, in particular, reinforced its reputation as the City of Lights by illuminating the

text: Place de l'Opéra

text: and the Avenue de l'Opéra as early as 1878, and in 1912

text: Edith Wharton

text: wrote home in distress that the city landmarks were lighted at night, "torn from their mystery by the vulgar intrusion of floodlighting." Conversely, since European cities had hardly any skyscrapers, lighting from within the building or on its facade dominated the use of light in modern architecture to an extent that it did not in America. Some buildings used glass illuminated from within; for example

text: Franz Jourdain

text: 's 1907 extension to the

text: Samaritaine

text: department store in Paris, with glass domes, and

text: Erich Mendelsohn

text: 's 1928 Petersdorff Department Store in Breslau, with ribbon windows illuminated by over-mounted neon lighting reflected out into the street by white curtains. The emphasis on bright, flat surfaces to simplify illumination helped to spread the architectural vocabulary of modernism. Architects themselves drew attention to and embraced the greater importance of lighted advertising, rather than the American approach of floodlighting a skyscraper like "a gleaming holy grail" or "the dream castle of Valhalla" and ignoring the possibilities for lettering of the "gigantic, widely visible wall areas". Häring went so far as to welcome "the destruction of architecture" by advertising:

text: In the effort to reduce light pollution, researchers have developed a "Unified System of Photometry," which is a way to measure how much or what kind of street lighting is needed. The Unified System of Photometry allows light fixtures to be designed to reduce energy use while maintaining or improving perceptions of visibility, safety, and security. There was a need to create a new system of light measurement at night because the biological way in which the eye’s rods and cones process light is different in nighttime conditions versus daytime conditions. Using this new system of photometry, results from recent studies have indicated that replacing traditional, yellowish, high-pressure sodium (HPS) lights with "cool" white light sources, such as induction, fluorescent, ceramic metal halide, or LEDs can actually reduce the amount of electric power used for lighting while maintaining or improving visibility in nighttime conditions.

text: In the effort to reduce light pollution, researchers have developed a "Unified System of Photometry," which is a way to measure how much or what kind of

text: street light

text: ing is needed. The Unified System of Photometry allows light fixtures to be designed to reduce energy use while maintaining or improving perceptions of visibility, safety, and security. There was a need to create a new system of light measurement at night because the biological way in which the eye’s rods and cones process light is different in nighttime conditions versus daytime conditions. Using this new system of photometry, results from recent studies have indicated that replacing traditional, yellowish,

text: high-pressure sodium

text: (HPS) lights with "cool" white light sources, such as induction,

text: fluorescent

text: ceramic metal halide

text: , or

text: LED

text: s can actually reduce the amount of electric power used for lighting while maintaining or improving visibility in nighttime conditions.

text: In the real world, objects and surfaces are visible due to the fact that they are reflecting light. This reflected light then illuminates other objects in turn. From that simple observation, two principles follow.

text: In a conventional lamp, the evaporated tungsten eventually condenses on the inner surface of the glass envelope, darkening it. For bulbs that contain a vacuum, the darkening is uniform across the entire surface of the envelope. When a filling of inert gas is used, the evaporated tungsten is carried in the thermal convection currents of the gas, depositing preferentially on the uppermost part of the envelope and blackening just that portion of the envelope. An incandescent lamp that gives 93% or less of its initial light output at 75% of its rated life is regarded as unsatisfactory, when tested according to IEC Publication 60064. Light loss is due to filament evaporation and bulb blackening. Study of the problem of bulb blackening led to the discovery of the Edison effect, thermionic emission and invention of the vacuum tube.

text: In a conventional lamp, the evaporated tungsten eventually condenses on the inner surface of the glass envelope, darkening it. For bulbs that contain a vacuum, the darkening is uniform across the entire surface of the envelope. When a filling of inert gas is used, the evaporated tungsten is carried in the thermal convection currents of the gas, depositing preferentially on the uppermost part of the envelope and blackening just that portion of the envelope. An incandescent lamp that gives 93% or less of its initial light output at 75% of its rated life is regarded as unsatisfactory, when tested according to IEC Publication 60064. Light loss is due to filament evaporation and bulb blackening. Study of the problem of bulb blackening led to the discovery of the

text: Edison effect, thermionic emission

text: and invention of the

text: vacuum tube

text: Contre-jour produces backlighting of the subject. This effect usually hides details, causes a stronger contrast between light and dark, creates silhouettes and emphasizes lines and shapes. The sun, or other light source, is often seen as either a bright spot or as a strong glare behind the subject. Fill light may be used to illuminate the side of the subject facing toward the camera. Silhouetting occurs when there is a lighting ratio of 16:1 or more; at lower ratios such as 8:1 the result is instead called low-key lighting.

text: Contre-jour produces

text: backlighting

text: of the subject. This effect usually hides details, causes a stronger contrast between light and dark, creates

text: silhouette

text: s and emphasizes lines and shapes. The

text: sun

text: , or other light source, is often seen as either a bright spot or as a strong glare behind the subject.

text: Fill light

text: may be used to illuminate the side of the subject facing toward the camera. Silhouetting occurs when there is a

text: lighting ratio

text: of 16:1 or more; at lower ratios such as 8:1 the result is instead called

text: low-key lighting

text: Visible-light astronomy encompasses a wide variety of observations via telescopes that are sensitive in the range of visible light (optical telescopes).  It includes imaging, where a picture of some sort is made of the object; photometry, where the amount of light coming from an object is measured, spectroscopy, where the distribution of that light with respect to its wavelength is measured, and polarimetry where the polarisation state of that light is measured.  An example of spectroscopy is the study of spectral lines to understand of what kind of matter light is going through. Visible astronomy also includes looking up at night (skygazing).  Visible-light astronomy is part of optical astronomy, and differs from astronomies based on invisible types of light in the electromagnetic radiation spectrum, such as radio waves, infrared waves, ultraviolet waves, X-ray waves and gamma-ray waves.

text: Visible-light astronomy encompasses a wide variety of

text: observation

text: s via

text: telescope

text: s that are sensitive in the range of

text: visible light

text: optical telescope

text: s).  It includes imaging, where a picture of some sort is made of the object;

text: photometry

text: , where the amount of light coming from an object is measured,

text: spectroscopy

text: , where the distribution of that light with respect to its

text: wavelength

text: is measured, and

text: polarimetry

text: where the

text: polarisation

text: state of that light is measured.  An example of

text: spectroscopy

text: is the study of

text: spectral line

text: s to understand of what kind of

text: matter

text: light is going through. Visible astronomy also includes looking up at night (

text: skygazing

text: ).  Visible-light astronomy is part of optical astronomy, and differs from astronomies based on invisible types of light in the

text: electromagnetic radiation spectrum

text: , such as

text: radio waves

text: infrared waves

text: ultraviolet waves

text: X-ray waves

text: and

text: gamma-ray waves

text: During the Edo period and Meiji period, the act of carrying a large lantern float like the Nebuta was often banned by the government due to the potential fire hazard it posed to the surroundings. This ban was also put into place during World War II, but was lifted in 1944 as an effort to boost morale during the waning years of the war. Corporations began to sponsor the creation of the floats in the post-war period, and a strong emphasis was placed in expanding local tourism through the festival. The light source within the float was originally a candle, but was eventually changed to incandescent or fluorescent light bulbs powered by portable generators and rechargeable batteries. The frame of the floats also changed from bamboo to wire, lowering the risk of fire considerably. Nebuta floats also grew larger with time, but urban obstacles such as footbridges, power lines, and traffic lights only allowed their width to increase significantly. The floats often feature images of kabuki actors, various types of gods, and historical or mythical figures from Japanese or Chinese culture, but modern Nebuta floats may also feature famous regional personalities or characters from television shows (especially the annual historical "Taiga drama" aired by NHK).

text: During the

text: Edo period

text: and

text: Meiji period

text: , the act of carrying a large

text: lantern

text: float like the Nebuta was often banned by the government due to the potential fire hazard it posed to the surroundings. This ban was also put into place during

text: World War II

text: , but was lifted in 1944 as an effort to boost morale during the waning years of the war. Corporations began to sponsor the creation of the floats in the post-war period, and a strong emphasis was placed in expanding local tourism through the festival. The light source within the float was originally a candle, but was eventually changed to incandescent or fluorescent light bulbs powered by portable generators and rechargeable batteries. The frame of the floats also changed from bamboo to wire, lowering the risk of fire considerably. Nebuta floats also grew larger with time, but urban obstacles such as footbridges, power lines, and traffic lights only allowed their width to increase significantly. The floats often feature images of

text: kabuki

text: actors, various types of gods, and historical or mythical figures from Japanese or Chinese culture, but modern Nebuta floats may also feature famous regional personalities or characters from television shows (especially the annual historical "

text: Taiga drama

text: " aired by

text: NHK

text: Before tracks can be visible, a tangential light source is needed. This illuminates the white droplets against the black background. Drops should be viewed from a horizontal position. If the chamber is working correctly, tiny droplets should be seen condensing. Often this condensation is not apparent until a shallow pool of alcohol is formed at the condenser plate. The tracks become much more obvious once temperatures and conditions have stabilized in the chamber.  This requires the elimination of any significant drift currents (poor chamber sealing).

text: The lighthouse was initially lit by kerosene, however the light source was later replaced by Dalén light using carbide (acetylene gas). Currently, it runs on electricity. The lighthouse's lantern has a 1,000 W light source. The light flashes twice in group white through a catadioptric reflector system with cylindrical lens having a focus length of  every 12 seconds 1.5 seconds long, which is visible at a range of . The lighthouse's foghorn blasts every 60 seconds in foggy conditions.

text: The lighthouse was initially lit by

text: kerosene

text: , however the light source was later replaced by

text: Dalén light

text: using

text: carbide

text: acetylene

text: gas). Currently, it runs on electricity. The lighthouse's lantern has a 1,000

text: W

text: light source. The light flashes twice in group white through a

text: catadioptric reflector system

text: with

text: cylindrical lens

text: having a focus length of  every 12 seconds 1.5 seconds long, which is visible at a range of . The lighthouse's

text: foghorn

text: blasts every 60 seconds in foggy conditions.

text: The airport plans to add another concourse in the next 5–10 years and looks to add more direct flights to the east coast; the Spokane market has been hosting big events and attracting business to the area.

text: In comparison with incandescent light bulbs, neon lamps have much higher luminous efficacy. Incandescence is heat-driven light emission, so a large portion of the electric energy put into an incandescent bulb is converted into heat. Non-incandescent light sources such as neon light bulbs, fluorescent light bulbs, and light emitting diodes are therefore much more energy efficient than normal incandescent light bulbs. Green neon bulbs can produce up to 65 lumens per watt of power input, while white neon bulbs have an efficacy of around 50 lumens per watt. In contrast, a standard incandescent light bulb only produces around 13.5 lumens per watt.

text: In comparison with

text: incandescent light bulbs

text: , neon lamps have much higher

text: luminous efficacy

text: Incandescence

text: is heat-driven light emission, so a large portion of the electric energy put into an incandescent bulb is converted into heat. Non-incandescent light sources such as neon light bulbs,

text: fluorescent light bulbs

text: , and

text: light emitting diodes

text: are therefore much more energy efficient than normal incandescent light bulbs.

text: Green

text: neon bulbs can produce up to 65 lumens per watt of power input, while white neon bulbs have an efficacy of around 50 lumens per watt. In contrast, a standard incandescent light bulb only produces around 13.5 lumens per watt.

text: Super Hits of the '70s: Have a Nice Day is a series of music compilations containing chiefly one-hit wonders and lesser-known pop and rock music songs from the 1970s. The first fifteen volumes were released on cassette and (with bonus tracks) on CD, in 1990 by Rhino Records, covering the years 1969–1976. Compiled by Gary Stewart, David McLees, and Bill Inglot, each CD comes with an eight-page booklet which includes five pages of liner notes by Paul Grein. Follow-up volumes appeared in 1993 and 1996, extending the time period to 1979 and with additional songs from the 1972-76 period, available on cassette or CD (ALL 25 volumes were issued in both formats). Each volume has twelve songs. Despite the greater capacity of compact discs, the running time of each of the volumes is no longer than the limit of vinyl records in the 1970s, from 38 to 45 minutes long.

text: Super Hits of the '70s: Have a Nice Day is a series of music

text: compilations

text: containing chiefly

text: one-hit wonders

text: and lesser-known

text: pop

text: and

text: rock music

text: songs from the 1970s. The first fifteen volumes were released on

text: cassette

text: and (with bonus tracks) on

text: CD

text: , in 1990 by

text: Rhino Records

text: , covering the years 1969–1976. Compiled by

text: Gary Stewart

text: David McLees

text: , and

text: Bill Inglot

text: , each CD comes with an eight-page booklet which includes five pages of liner notes by

text: Paul Grein

text: . Follow-up volumes appeared in 1993 and 1996, extending the time period to 1979 and with additional songs from the 1972-76 period, available on cassette or CD (ALL 25 volumes were issued in both formats). Each volume has twelve songs. Despite the greater capacity of compact discs, the running time of each of the volumes is no longer than the limit of

text: vinyl records

text: in the 1970s, from 38 to 45 minutes long.

text: In addition he is a member of Islamic Iran Participation Front and Islamic Iran Participation Front's Central Council.

text: In addition he is a member of

text: Islamic Iran Participation Front

text: and

text: Islamic Iran Participation Front's Central Council

text: The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of comparable hue to that of the light source. Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, horticulture, and other fields. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e., those on a line from reddish/orange via yellow and more or less white to blueish white; it does not make sense to speak of the color temperature of, e.g., a green or a purple light. Color temperature is conventionally stated in the unit of absolute temperature, the Kelvin, having the unit symbol K.

text: temperature

text: of an ideal

text: black-body radiator

text: that radiates light of comparable

text: hue

text: visible light

text: that has important applications in

text: lighting

text: photography

text: videography

text: publishing

text: manufacturing

text: astrophysics

text: horticulture

text: , and other fields. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e., those on a line from reddish/orange via yellow and more or less white to blueish white; it does not make sense to speak of the color temperature of, e.g., a green or a purple light. Color temperature is conventionally stated in the unit of absolute temperature, the

text: Kelvin

text: , having the unit symbol K.

text: The spectral power distribution (SPD) of a source describes how much flux reaches the sensor over a particular wavelength and area. This effectively expresses the per-wavelength contribution to the radiometric quantity being measured. The SPD of a source is commonly shown as an SPD curve. SPD curves provide a visual representation of the color characteristics of a light source, showing the radiant flux emitted by the source at various wavelengths across the visible spectrum It is also a metric by which we can evaluate a light source’s ability to render colors, that is, whether a certain color stimulus can be properly rendered under a given illuminant.

text: The spectral power distribution (SPD) of a source describes how much flux reaches the sensor over a particular wavelength and area. This effectively expresses the per-wavelength contribution to the radiometric quantity being measured. The SPD of a source is commonly shown as an SPD curve. SPD curves provide a visual representation of the color characteristics of a light source, showing the radiant flux emitted by the source at various wavelengths across the visible spectrum It is also a metric by which we can evaluate a light source’s ability to render colors, that is, whether a certain color stimulus can be properly rendered under a given

text: illuminant

text: TitleVest established and maintains New York City’s largest digital library of condominium and cooperative offering plans — books containing the history of coop or condo residences as well as their rules and regulations — and currently holds more than 5,000 offering plans in its online database.

text: TitleVest established and maintains

text: New York City

text: ’s largest

text: digital library

text: of

text: condominium

text: and

text: cooperative

text: offering plans — books containing the history of coop or condo residences as well as their rules and regulations — and currently holds more than 5,000 offering plans in its online database.

text: Shadowboxing (, Boy s tenyu; literally "Fight with shadow") is a 2005 Russian 4-episode Sports drama movie.

text: Shadowboxing (, Boy s tenyu; literally "Fight with shadow") is a 2005 Russian 4-episode

text: Sports drama

text: movie.

text: One of the problems of the standard electric light bulb is filament notching due to evaporation of the filament. Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. These hot spots evaporate faster than the rest of the filament, which increases the resistance at that point—this creates a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. Irving Langmuir found that an inert gas, instead of vacuum, would retard evaporation. General service incandescent light bulbs over about 25 watts in rating are now filled with a mixture of mostly argon and some nitrogen, or sometimes krypton. Lamps operated on direct current develop random stairstep irregularities on the filament surface which may cut lifespan in half compared to AC operation; different alloys of tungsten and rhenium can be used to counteract the effect.

text: One of the problems of the standard electric light bulb is filament notching due to evaporation of the filament. Small variations in

text: resistivity

text: along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. These hot spots evaporate faster than the rest of the filament, which increases the resistance at that point—this creates a

text: positive feedback

text: that ends in the familiar tiny gap in an otherwise healthy-looking filament.

text: Irving Langmuir

text: found that an inert gas, instead of vacuum, would retard evaporation. General service incandescent light bulbs over about 25 watts in rating are now filled with a mixture of mostly

text: argon

text: and some

text: nitrogen

text: , or sometimes

text: krypton

text: . Lamps operated on direct current develop random stairstep irregularities on the filament surface which may cut lifespan in half compared to AC operation; different alloys of tungsten and

text: rhenium

text: can be used to counteract the effect.

text: It was suggested in 2003 that PfATP6 is a target of artemisinin antimalarials, and also that a single amino acid mutation in the enzyme can mediate resistance to this important group of compounds. The main evidence came from a Xenopus oocyte system describing specific interactions between artemisinins and PfATP6 as well as E255L-mutated mammalian SERCA. However an independent reappraisal in the same system showed that while PfATP6 protein could be detected, it was inactive. In the independent oocyte work, mammalian SERCA and its E255L-mutated version were active but both were insensitive to artemisinin, again in contrast to the original claims. The authors suggested that the original results might have been affected by low ATPase signals, few experimental repeats and large standard deviations. The lack of artemisinin inhibition of E255L mammalian SERCA matched results from heterologous expression in mammalian and yeast cells.

text: In the study of illumination, a variety of sources are linear in nature, most commonly the fluorescent tube, During the process of interior lighting design it is important to calculate the light intensity at work stations or other user areas, not only to ensure sufficient light is present, but more importantly to avoid over-illumination and its attendant energy wastage as well as adverse health effects.  Thus the scientists involved in light transmission calculations employ computer models that recognize linear sources when fluorescent fixtures are used.  In a typical setting there may be hundreds of finite length light sources that comprise the light output in an office environment. A related concept are the ultraviolet tubes used in phototherapy, where output radiation from the tube can be accurately modeled by treating the tube as a line source. On a larger scale, an illuminated roadway may act as a line source of light pollution.

text: In the study of illumination, a variety of sources are linear in nature, most commonly the

text: fluorescent tube

text: , During the process of interior lighting design it is important to calculate the light intensity at work stations or other user areas, not only to ensure sufficient light is present, but more importantly to avoid

text: over-illumination

text: and its attendant

text: energy wastage

text: as well as adverse health effects.  Thus the scientists involved in light transmission calculations employ computer models that recognize linear sources when fluorescent fixtures are used.  In a typical setting there may be hundreds of finite length light sources that comprise the light output in an office environment. A related concept are the

text: ultraviolet

text: tubes used in

text: phototherapy

text: , where output radiation from the tube can be accurately modeled by treating the tube as a line source. On a larger scale, an illuminated

text: roadway

text: may act as a line source of

text: light pollution

text: UFO advocate Jim Dilettoso claimed to have performed "spectral analysis" of photographs and video imagery that proved the lights could not have been produced by a man-made source. Dilettoso claimed to have used software called "Image Pro Plus" (exact version unknown) to determine the amount of red, green, and blue in the various photographic and video images and construct histograms of the data, which were then compared to several photographs known to be of flares. Several sources have pointed out, however, that it is impossible to determine the spectral signature of a light source based solely on photographic or video imagery, as film and electronics inherently alter the spectral signature of a light source by shifting hue in the visible spectrum, and experts in spectroscopy have dismissed his claims as being scientifically invalid. Normal photographic equipment also eliminates light outside the visible spectrum (for example, infrared and ultraviolet) that would be necessary for a complete spectral analysis. The maker of "Image Pro Plus", Media Cybernetics, has stated that its software is incapable of performing spectroscopic analysis.

text: UFO advocate Jim Dilettoso claimed to have performed "

text: spectral analysis

text: " of photographs and video imagery that proved the lights could not have been produced by a man-made source. Dilettoso claimed to have used software called "Image Pro Plus" (exact version unknown) to determine the amount of red, green, and blue in the various photographic and video images and construct histograms of the data, which were then compared to several photographs known to be of flares. Several sources have pointed out, however, that it is impossible to determine the spectral signature of a light source based solely on photographic or video imagery, as film and electronics inherently alter the spectral signature of a light source by shifting hue in the visible spectrum, and experts in spectroscopy have dismissed his claims as being scientifically invalid. Normal photographic equipment also eliminates light outside the visible spectrum (for example,

text: infrared

text: and

text: ultraviolet

text: ) that would be necessary for a complete spectral analysis. The maker of "Image Pro Plus",

text: Media Cybernetics

text: , has stated that its software is incapable of performing spectroscopic analysis.

text: The term specular means that light is perfectly reflected in a mirror-like way from the light source to the viewer. Specular reflection is visible only where the surface normal is oriented precisely halfway between the direction of incoming light and the direction of the viewer; this is called the half-angle direction because it bisects (divides into halves) the angle between the incoming light and the viewer. Thus, a specularly reflecting surface would show a specular highlight as the perfectly sharp reflected image of a light source. However, many shiny objects show blurred specular highlights.

text: The term specular means that light is

text: perfectly reflected

text: in a mirror-like way from the light source to the viewer. Specular reflection is visible only where the

text: surface normal

text: is oriented precisely halfway between the direction of incoming light and the direction of the viewer; this is called the half-angle direction because it bisects (divides into halves) the angle between the incoming light and the viewer. Thus, a specularly reflecting surface would show a specular highlight as the perfectly sharp reflected image of a light source. However, many shiny objects show blurred specular highlights.