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Topic: Luminous efficacy

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Luminous efficiency

Lumen (unit)

Luminous flux

Luminous intensity

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	Luminous efficacy - Wikipedia, the free encyclopedia
		Luminous efficacy is the ratio of the total apparent power of a light source to its actual total power.
		Luminous efficacy measures the fraction of power which is useful for lighting.
		The luminous coefficient is unity for a narrow band of wavelengths at 555 nanometres.
	en.wikipedia.org /wiki/Luminous_efficacy (664 words)

	Luminous energy - Wikipedia, the free encyclopedia
		In photometry, luminous energy is the perceived energy of light.
		Luminous energy is not the same as the radiant energy, the corresponding objective physical quantity.
		The SI unit of luminous energy is the lumen second, which is unofficially known as the Talbot in honor of William Henry Fox Talbot.
	en.wikipedia.org /wiki/Luminous_energy (173 words)

	Megaray - The long range hand held searchlight,Night Vision Optics SA,night vision,surveillance,security,search,rescue (Site not responding. Last check: 2007-10-30)
		The lumen is the standard unit for the luminous flux of a light source.
		The luminous flux is the part of the power which is perceived as light by the human eye, and the figure 683 lumens/watt is based upon the sensitivity of the eye at 555 nm, the peak efficiency of the photopic (daylight) vision curve.
		The luminous efficacy is 1 at that frequency.
	www.megaray.com /Light_Consept.html (460 words)

	Physics Tutoring: Electromagnetic Waves (Site not responding. Last check: 2007-10-30)
		luminosity factor: The ratio of the luminous flux in lumens emitted by a source at a particular wavelength to the corresponding radian flux, in watts, at the same wavelength this is a measure of the visual sensitivity of the eye.
		luminous coefficient: A measure of the fraction of the radian power of a light source which contributes to its luminous properties, equal to the average of the luminosity function at various wavelengths, weighted according to the spectral intensity of the source.
		luminous intensity: The luminous flux incident on a small surface which lies in a specified direction from a light source and is normal to this direction, divided by the solid angle (in steradian) which the surface subtends at the source of light.
	www.slcc.edu /schools/hum_sci/physics/tutor/2220/em_waves (1034 words)

	Metrics for solid-state lighting (May 2005) - Features - LEDs Magazine
		Luminous efficacy of a source is the ratio of lumens (total luminous flux) to watts (total electrical power input).
		However, luminous efficacy of radiation is the ratio of luminous flux to radiant power, which is a theoretical maximum that a light source with a given spectral distribution can achieve with a 100% radiant efficiency.
		Efficacy improvements are often said to be following the same trends as performance improvement in LEDs, where performance is the percentage increase of radiant efficiency over a given time period, However, and this should be obvious, LED luminous efficacies must level off because they cannot double repeatedly without end.
	www.ledsmagazine.com /articles/features/2/5/4/1 (2139 words)

	[No title]
		] The unit of luminous flux, equal to the luminous flux emitted within a unit solid angle (1 steradian) from a point source having a uniform intensity of 1 candela, or to the luminous flux received on a unit surface, all points of which are at a unit distance from such a source.
		] The ratio of luminous flux in lumens emitted by a source at a particular wavelength to the corresponding radiant flux in watts at the same wavelength; thus this is a measure of the visual sensitivity of the eye.
		] The luminous flux incident on a small surface which lies in a specified direction from a light source and is normal to this direction, divided by the solid angle (in steradians) which the surface subtends at the source of light.
	www.accessscience.com /Dictionary/L/L24/DictL24.html (2348 words)

	LEDs with Punch!
		Luminous efficacy of the emitted light was estimated to mostly be 440 to 480 lumens per watt.
		Estimated luminous efficacy of the emitted light was mainly 450-475 lumens per watt, maybe as low as 420-440 for the bluest one and as high as 520-525 for one that was noticeably more of a lime green than the other 55 of the 56 good pieces.
		Agilent claims that typical luminous efficacy of the emitted light of their blue LEDs of 470 nm peak wavelength and 472 nm dominant wavelength is 75 lumens per emitted watt.
	wearcam.org /ece385/lecture6/high_brightness_led.htm (7952 words)

	LEDs with Punch!
		It is notable that this level of overall luminous efficacy is in the range of that of fluorescent lamps.
		The datasheet claims a typical overall luminous efficacy of 31 lumens/watt at a favorable current of 160 mA (a heat sink is recommended).
		A lumen is defined as the "luminous flux" of 1/683 of a watt of monochromatic light that has a frequency of 540 terahertz, or a wavelength of approx.
	members.misty.com /don/led.html (9446 words)

	How many R,G,B LEDs for white
		Luminous output is assumed to be.85 lumen at 20 mA.
		Luminous output is assumed to be 2.6 lumens at 20 mA.
		Luminous output is assumed to be.45 lumen at 20 mA.
	members.misty.com /don/ledrgb2w.html (1288 words)

	OSRAM SYLVANIA:Sylvania Automotive Lighting Catalog
		It is the ratio between luminous flux and the area to be illuminated.
		The luminance L of a light source or an illuminated area is a measure of how much the eye is stimulated and therefore of how great an impression of brightness is created in the brain.
		The luminous efficacy of conventional incandescent lamps (such as R5 W) is typically 10 lm/W, that of tungsten-halogen lamps (such as H7) 26 lm/W, and that of gas discharge lamp (such as D2S) 91 lm/W. Color temperature
	www.sylvaniaautocatalog.com /new_sylvania/glossary.htm (1016 words)

	LEDs with punch
		Unless otherwise noted, luminous efficacy is stated for a 25 degree Celsius (77 degree F.) ambient with a current of 20 milliamps.
		The overall luminous efficacy of slightly orangish red and red-orange Hewlett Packard models using their "InGaAsP II" semiconductor material is in the 17-23 lumen per watt range.
		The luminous efficacy of their green LEDs is extremely close to that of the Nichia ones.
	www.k3pgp.org /Notebook/Lasersam/led.htm (3593 words)

	[No title] (Site not responding. Last check: 2007-10-30)
		One of the principal goals motivating advances in lighting technology is maximization of luminous efficacy, the ratio of the total luminous flux to total power input (i.e., the "amount of light" per Watt).
		There are cases where the efficacy of a new electric light source technology is very high but the color properties are unsuitable.
		It is possible to exchange some efficacy for better colorimetric properties: there are an infinite number of ways to filter a broad-spectrum light so that it has better colorimetric properties.
	delta.cs.cinvestav.mx /~ccoello/EMOO/abstract_eklund.txt (327 words)

	[No title]
		He is firstly referring to luminous efficacy, which is where the 683 comes from.
		Luminous flux in general assumes photopic vision, which is where the 545nm comes from (although Wyszecki & Stiles give it as 555nm).
		Note that the actual output of a flat illum surface is the radiance or luminance multiplied by the projected area, that is, the surface area times the cosine to the normal.
	radsite.lbl.gov /radiance/pub/digest/no_Z/v2n6 (12947 words)

	Candela
		The dimensions are the same as in the radiant case, but this time it's multiplied by the luminous efficacy.
		and luminous intensity is that, with a correction factor for it to be useful for human perception.
		Luminous flux is the rate at which 'uminous energy energy is passing through the surface.
	www.physicsforums.com /showthread.php?p=301824 (1163 words)

	Incandescent and Arc Lamps (Site not responding. Last check: 2007-10-30)
		The further away a luminous source is away from the Planck curve (the curve of a fl body), the less meaning the value of its color temperature.
		Theoretical maximum luminous efficacy is 683 lm/W where all the electrical power would be converted into a spectral line at 555nm.
		Household lamps (tungsten filaments) have a luminous efficacy of 14-15 lm/W and color temperature of 2900 degrees Kelvin.
	vsg.cape.com /~pbaum/lamp.htm (746 words)

	Tungsten Halogen Lamps (Site not responding. Last check: 2007-10-30)
		High voltage tungsten halogen lamps have a luminous efficacy of about 22 lm/W. Common luminous efficacy is about 30 lm/W and color temperature for studio lighting of 3200 degrees Kelvin.
		If filtering a 3200 degrees Kelvin light to daylight, luminous efficacy is lowered to 7.5 lm/W. XENONPHOT at 37 lm/W, is at the maximum practical limit, because the lamp must be handled mechanically and switched on electrically.
		Using Xenon (larger atoms) the temperature can be raised to increase the luminous efficacy by 5%-10% and color temperature by about 100 degrees Kelvin.
	www.vsg.cape.com /~pbaum/halogen.htm (1920 words)

	Introduction – Enhanced Night Visibility Volume XVII VES Characterization – December 2005
		The luminous flux, measured in lumens (lm), is the radiant flux of a source evaluated in terms of the human visual response.
		The flux reflected or emitted from a surface or through a projected area that is propagated in a given direction per unit solid angle is defined as the radiance or luminance of the area.
		The radiant or luminous intensity from a source is a measure of the directional aspects of the emitted radiation.
	www.tfhrc.gov /safety/hsis/pubs/04148/introduction.htm (1334 words)

	RPI: News & Information - New, Unified System of Photometry Addresses Lighting for Mesopic Vision
		The first and most common method, the photopic luminous efficacy function, represents the spectral sensitivity of the eye during the daytime.
		The second, known as the scotopic luminous efficacy function, characterizes sensitivity in near-complete darkness.
		“The problem with the current photometry system is that it remains unclear which luminous efficacy function should be used for nighttime applications where electric lighting is used, such as driving down the road at night,” says Rea, who directed the LRC team’s research into the new system.
	news.rpi.edu /update.do?artcenterkey=608&setappvar=page(1) (514 words)

	Dr
		However, more improvements are still needed; low luminous efficacy has been a major drawback of PDPs until now.
		The most essential enhancement that must be carried out if PDP televisions are to come into widespread use is to improve their luminous efficacy to achieve a bright picture with low power consumption.
		Some of the main factors that determine the luminous efficacy of PDPs are cell structure, gas composition, phosphor characteristics and driving scheme.
	www.physics.ucdavis.edu /Abstracts/I.Lee.htm (189 words)

	An Experimental Determination of the Maximum Spectral Luminous Efficacy of Radiation
		An Experimental Determination of the Maximum Spectral Luminous Efficacy of Radiation
		An experimental determination of the maximum spectral luminous efficacy of radiation has been made.
		The method uses luminous intensity standard lamps calibrated in "World mean candela 1952", thermopiles calibrated by absolute radiometers of electrical substitution type and filters of which the spectral transmittance is approximately proportional to the relative spectral luminous efficiency.
	stacks.iop.org /0026-1394/11/165 (226 words)

	Laser Focus World - X-ray imagery aids HID lamp design
		While the luminous efficacy of incandescent lamps is limited to less than 20 lumens per watt, the luminous efficacy of HID sources can be as high as 125 lumens per watt.
		Despite the high luminous efficacy of metal-halide HID lamps, however, the full scope of their operating characteristics is not entirely understood.
		Ongoing research seeks better understanding in hopes of improving luminous efficacy and color quality (measured in terms of color-rendering index) even further, according to John Curry, a research scientist at the National Institute of Standards and Technology (NIST; Gaithersburg, MD).
	lfw.pennnet.com /articles/article_display.cfm?article_id=236210 (518 words)

	The calculation of the luminous efficacy of a semiconductor lamp
		The calculation of the luminous efficacy of a semiconductor lamp
		An analytical expression for the luminous efficacy of a semiconductor lamp is derived by representing both the eye response curve and the spectral output of a lamp by gaussian functions and integrating the product.
		Numerical values are given for lamps whose outputs are centred between 545 and 730 nm.
	stacks.iop.org /0022-3727/6/L80 (211 words)

	LEDs Magazine - light emitting diodes, solid state lighting > Products
		The second generation of high-intensity powerLED EOS modules from TridonicAtco GmbH & Co. KG, Dornbirn/Austria offer significant improvements in efficiency and luminous efficacy – the daylight white version achieves a luminous flux of up to 70 lm per light source.
		The outstanding photometric properties of the modules when operated on the new matching 700 mA converters offer the ideal basis for finding new applications for LED light, such as replacing low-voltage halogen lamps or small compact fluorescent lamps.
		These compact light sources, particularly in white, have a unique combination of luminous efficacy, colour tolerance and colour rendering.
	www.ledsmagazine.com /press/12170 (738 words)

	Breakthrough Technology Accelerates Solid-State Lighting \| Press Release
		Commercially available white LEDs combine a light-emitting semiconductor with a phosphor, a rare earth compound, to produce visible white light.
		Compared to commercial white LEDs, prototypes of the new SPE LED technology produced 30-60 percent more light output and luminous efficacy-light output (lumens) per watt of electricity.
		Further research into the SPE technology could result in even higher levels of light output and greater luminous efficacy, according to Narendran.
	www.lrc.rpi.edu /resources/news/pressReleases/spemethod.asp (892 words)

	Solid State Lighting: Enhanced Optical Efficiency Package Incorporating Nanotechnology
		Due to elimination of light-scattering, the researcher anticipates a significant enhancement of the luminous efficacy of high brightness LED-based white lamps for general illumination applications.
		Appropriate surface modification will be developed for each of the nanophosphors to disperse into silicone-based matrices without agglomeration to achieve high optical transparency in the visible-spectral region.
		When fully optimized, the high refractive-index nanocomposites and nanophosphors are expected to increase white light emission by 100%, bringing the luminous efficacy of white light to 75 lm/W using a cost-effective packaging technology.
	www.netl.doe.gov /ssl/rd/EnhancedOpticalEfficiency.html (251 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations (Site not responding. Last check: 2007-10-30)
		Of all the atmospheric constituents, aerosol content is shown to be responsible for the greatest variations in direct luminous efficacy.
		Based on these results and Dogniaux`s illuminance turbidity factor, T{sub il}, two direct luminous efficacy models are derived, one of which is tuned to our experimental data.
		The input parameters are optical air mass,{Beta}, and water vapor content in the tuned version.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=219850 (284 words)

	High Intensity Discharge (HID) Lamps, Ballasts, and Fixtures
		Here you will learn to optimize fluorescent lighting design in new applications and to improve or retrofit HID lighting in existing facilities.
		Explained here are the selection factors for HID lamps, including light output, lumen depreciation, wattage, efficiency (called “luminous efficacy” by specialists), lamp color, color rendering, service life, operating temperatures, mounting position limitations, cost, and other factors.
		Also explained are the selection factors for HID ballasts, which must be matched precisely to the lamps.
	www.energybooks.com /toc/toc0903.htm (483 words)

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