A BRIGHT FUTURE FOR LIGHT

ASEE Prism, Dec 2004 by Grose, Thomas K

INNOVATION

A STANDARD incandescent light bulb will glow for about 500 hours. A fluorescent tube light might last 5,000. But now researchers at Rensselaer Polytechnic Institute say they've developed a LED (light-emitting diodes) bulb that will burn brightly for 50,000 hours-that's nearly 6 years, if left burning continuously. LED lights-which are tiny granules of semiconductor chips covered with arrays of plastic bulbs-have long life spans, and consume less electricity than standard lighting. That's why they're increasingly used for traffic signals and signs, and automotive lighting. But current versions aren't bright enough to replace standard bulbs. To increase LED brightness, the light generated has to be reflected inside the chips, and reflectors so far haven't been up to the task. But a team led by Renssalaer's Fred Schubert invented what it calls an ODR, an omnidirectional reflector that reflects the light at nearly 100 percent. An ODR bulb, Schubert says, will consume half as much electricity as today's bulbs, making them a green option. Certainly LED lights will cost more, but consumers will have to factor in how much they'll save on electric bills. He's close to signing a deal with a major Asian LED manufacturer. -TG