On-chip lamp scores a bull's-eye.Etching etching, the art of engraving with acid on metal; also the print taken from the metal plate so engraved. In hard-ground etching the plate, usually of copper or zinc, is given a thin coating or ground of acid-resistant resin. a series of concentric Coming from the center, or circles within circles. For example, tracks on a hard disk are concentric. Tracks on optical media are concentric or spiral shaped (in a coil) depending on the type. ridges around the lamp-on-a-chip known as a light-emitting diode, or LED, flings forward light that otherwise would be lost to the sides or back of the device. The ridges boost an LED's brightness seven-fold compared with the same LED without the ridges, Mark Y. Su and Richard P. Mirin mir·in n. A sweet Japanese rice wine used especially in cooking. [Japanese : Middle Chinese mei, flavor + Middle Chinese lan, , both of the National Institute of Standards and Technology National Institute of Standards and Technology, governmental agency within the U.S. Dept. of Commerce with the mission of "working with industry to develop and apply technology, measurements, and standards" in the national interest. in Boulder, Colo., report in the July 17 Applied Physics Letters Applied Physics Letters is a weekly peer-reviewed scientific journal published by the American Institute of Physics devoted to the publication of new experimental and theoretical papers about applications of physics to science, engineering, and modern technology. . The physicists used experimental LEDs that they had designed to emit TO EMIT. To put out; to send forth, 2. The tenth section of the first article of the constitution, contains various prohibitions, among which is the following: No state shall emit bills of credit. infrared radiation when illuminated by an infrared laser. Su says that he expects ridges to also improve performance of standard LEDs, which emit light in response to electric current. Interference among light waves passing through the ridges bends those waves' paths in the right direction, Su explains. The researchers note that ordinary LEDs send about 98 percent of their emissions in directions where the light goes to waste. In contrast, the new devices, which include a mirror beneath the LED as well as the ridges around it, project about 40 percent of their light forward, the team reports. LEDs are increasingly replacing many conventional lamps--for instance, in flashlights, vehicle taillights, and traffic signals (SN: 5/20/06, p. 314). However, adding ridges and mirrors to the various visible-light LEDs will require further research, Su says. Because such modifications might make the costs of common LEDs excessive, manufacturers are more likely to apply the enhancements to high-performance LEDs, such as those used in optical telecommunications, Su says. |
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