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.

Incandescent Light Bulb
Thomas Alva Edison was one of the greatest inventors. The light bulb was the brightest one among his inventions. Another great invention vacuum tube was also inspired from the light bulb. The goal was only to provide a method of supplying the world with inexpensive, widely available commercial lighting. It was a great achievement, but some flaws were revealed in coming centuries.