Efficacy, power and costs of high brightness LEDs have got levels that make them an attractive solution in many lighting system applications. The luminous efficacy of a light source is the ratio between the emitted luminous flux and the amount of the absorbed energy to transmit it. It is expressed in lumen/watt (lm/W). The lumen, the measure unit of the luminous flux, is equal to the luminous flux detected in a solid angle of one steradian and emitted towards all directions from a source with a luminous intensity of 1 candle. (the steradian –sr symbol- is the SI unit of solid angle and it is defined as " the solid angle subtended at the center of a sphere of radius r by a portion of the surface of the sphere having an area r ²".

1. Luminous Efficacy http://dev.emcelettronica.com/print/51770
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Luminous Efficacy
By Emanuele
Created 16/04/2008 - 10:36
BLOG Diodes
by Franco Musiari [ Assipe [1]]
Efficacy, power and costs of high brightness LEDs have got levels that make them an
attractive solution in many lighting system applications.
The luminous efficacy of a light source is the ratio between the emitted luminous flux and the
amount of the absorbed energy to transmit it. It is expressed in lumen/watt (lm/W). The
lumen, the measure unit of the luminous flux, is equal to the luminous flux detected in a solid
angle of one steradian and emitted towards all directions from a source with a lu