lumen

(redirected from unit of luminous flux)
Also found in: Dictionary, Thesaurus, Medical.

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.
..... Click the link for more information.
.

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.