ABSTRACT
Over the past four decades LEDs have continued to evolve, with remarkable progress in the past decade. They have moved from being indicators to light source and have begun to replace conventional sources in a variety of niche lighting applications. LEDs have the potential to replace conventional lighting technology for general illumination if targeted cost and performance breakthroughs can be achieved. LEDs are now available in all colors, as well as white utilizing phosphor down conversion. The best reported LED has a performance of 100 lumens/watt, a 1000X improvement over the early high volume devices, reflecting a 10X/decade rate of improvement. The cost per lumen has also decreased at about 10X/decade driven mainly by the performance improvement since the price of an LED has remained in the general vicinity of $0.1 since the early 70's. The most powerful LED emits over 100 Lumens of light, 10,000 times more then the early LEDs.
