LED's everywhere

Light emitting diodes (LED's) have been growing in power and finding new uses since 1993, when the blue LED was invented and could be mixed with red and green to make white light. They are still expensive, but last 50 times as long as a conventional bulb, and use a lot less power. However, white LED's are not as efficient as they might be, because almost half of the output is wasted, reflected inward by the phosphor that produces the visible output. This week, Scientists at the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute announced a new advance that solves this problem.According to the press release,"We have developed a technology based on a new scattered photon extraction (SPE) method that will speed up the progress of solid-state lighting and help secure our nation's energy future," said Nadarajah Narendran, Ph.D., director of research at the LRC. "The new technology dramatically increases light output and efficacy of white LEDs, and could play a fundamental role in the evolution of white LEDs for lighting in homes and offices."

Lightbulb efficiency is measured by the number of lumens produced per watt of power. A conventional light bulb puts out 14 lm/w; a compact flourescent 60 lm/w. The SPE LED achieves 80 lm/w and they are aiming for 150lm/w- over 10 times the efficiency of current bulbs.

Many people prefer the colour balance of conventional incandescent bulbs, and like the fact that one can use a dimmer. Compact flourescents do not quite hit the right colour temperature and cannot be dimmed.

WIth LED's. we will be able to dial up not only the intensity but the colour balance- warmer, redder light for sunset dinner parties; cool and bright for working. ::Lighting Research Center by [LA]