by Franco Musiari [ Assipe ]
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.