|MadSci Network: Physics|
Dear Bill, Here are short answers to your questions, followed by an extremely informative link to LED theory, design, and manufacture. (1) One technique used to produce white LEDs is by using a blue LED epoxied into a cup-shaped reflector with a phosphor-containing dye (such as Coumarin 6, used in dye lasers). The blue LED emits light. The dye, in turn, is stimulated by the blue light through a charge-transfer reaction and emits a broad spectrum of color. Together, these are preferentially designed to "mimic" the appearance of white light by the human eye. (2) Yes, when they become affordable. Right now, a white light LED equivalent to a 30 Watt bulb costs ~$160/each. (3) The electricity-to-light conversion efficiency is reported as high as 98-99%. This means almost zero heat production. (4) Yes, here it is... => http://www.rpi.edu/~schubert//Light-Emitting-Diodes-dot-org/ This summarizes much of the work done by Professor E. Fred Shubert of Rensselaer Polytechnic Institute in Troy, NY. It's a fantastic website for all things LED! Good Luck! ---* Dr. Ken Beck
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