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lumen

   Also found in: Dictionary/thesaurus, Medical, Acronyms, Wikipedia, Hutchinson 0.07 sec.
lumen: see photometry photometry (fōtŏm`ətrē)
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A unit of measurement of the amount of brightness that comes 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 13 lumens; a 100 watt bulb generates 1,200 lumens.

Lumen Ratings for Data Projectors
When choosing a data projector, the lumen rating is an important specification. In a darkened room, 500 lumens may be ample; however, in a conference room with normal lighting, 1,000 lumens would be better. In a room with daylight, 2,000 lumens is preferred. The standard lumen rating of a data projector is the average of photometer readings at several points on a full white image on the screen. See ANSI lumen, candela and spectrum.



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? Mentioned in ? References in classic literature
 
They fancy some foul, obscure den, some horrible Tartarus "informis, ingens, cui lumen ademptum.
Uncle Tom's Cabin by Stowe, Harriet Beecher View in context
- And afterwards, Non cui profundum Cæcitas lumen dedit Dircæus augur vidit hunc alto sinu, &c.
Poems by Poe, Edgar Allan View in context
Above him was the throat of the balloon bunched and tied together, but with an open lumen through which,Bert could peer up into a vast, empty, quiet interior, and out of which descended two fine cords of unknown import, one white, one crimson, to pockets below the ring.
The War in the Air by Wells, H.G. View in context
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