lumen

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lumen:

see photometryphotometry
, branch of physics dealing with the measurement of the intensity of a source of light, such as an electric lamp, and with the intensity of light such a source may cast on a surface area.
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Lumen

A unit of light from one source. Light falling on 1 square foot of surface of an imaginary sphere having a 1-foot radius around 1 candle.

Lumen

 

the unit of luminous flux in the International System of Units. Symbol, 1m. One lumen is the luminous flux emitted by an isotropic point source in a with a luminous intensity of 1 candela in a solid angle of 1 steradian.

lumen

[′lü·mən]
(anatomy)
The interior space within a tubular structure, such as within a blood vessel, a duct, or the intestine.
(optics)
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. Symbolized lm.
(science and technology)
The space within a tube.

lumen (lm)

The SI unit of luminous flux equal to the luminous flux received on a unit surface, all points of which are equidistant from a point source having a uniform intensity of 1 candela.

lumen

A unit of measurement of the light intensity radiating in the air in all directions from a light source. Lumens define "luminous flux," which is energy within the range of frequencies we perceive as light. For example, a wax candle generates about 13 lumens; a 60-watt bulb approximately 800, and a 100-watt bulb 1,600 lumens.

Lumen Ratings for Data Projectors
When choosing a data projector, the lumen rating is an important specification. In a small, dark room, 500 lumens may be ample; however, in a conference room with normal lighting, 1,000 to 2,000 lumens is required. In a large, well-lit room, at least 2,000 lumens is necessary. This rating is derived by taking the average of photometer readings at several points on a full white image on the screen. See lux, ANSI lumen, Lm/W, candela and spectrum.
References in periodicals archive ?
There are numerous bezels, lenses and tail caps for over 144 configurations and up to 900 lumens.
Simply changing the beam direction does not change the inherent lumen output of the source, and does not increase the solid angle, and therefore cannot improve the efficacy of a fixture from 17 lumens per watt to 100 lumens per watt.
The Lumens were incorporated into this awards program, even as the Lumen Awards continued to expand rapidly and continuously evolved to meet the needs of the IESNYC members and others who submitted projects for consideration of a Lumen Award.
Multi-lumens now have various lumen sizes within the single shaft, making concentricity of each lumen more difficult to achieve along with obtaining the right wall thickness for each lumen's intended application.
To figure out how many total lumens one candle is actually putting out in all directions you have to go back to your high school geometry (for which I apologize) and remember your formulas for figuring out the surface area of a sphere.
Month after month, we are saving an incredible amount of energy with the Digital Lumens system, while our light quality has actually improved," said Jon Barnes, Supply Chain Director for Ardo UK.
EB-Z8450WU/EB-Z8455WU with 700011 lumens of white and 7000 lumens colour light output, WUXGA resolution, RRP $18,799.
LLD is commonly computed as a ratio of mean to initial lumens, where mean lumens are taken to be the lumens produced at 40% of rated life.
Another reason you need more lumens is that a CFL will dim over time.
The two remaining organizations are developing OLEDs, one of which hopes to produce 50 lumens per watt.
Each fiber can deliver about 400 lumens, comparable to the light from a 30-watt incandescent bulb, notes David Beshears, one of the developers.