New photodetector uses gallium arsenide quantum well
Inframetrics (Billerica, MA) and the Jet Propulsion Laboratory (JPL; Pasadena, CA) produced a long-wavelength infrared (IR) camera that weighs only 2.5 lb and measures 5.3 ¥ 9.7 ¥ 2.5 in. The hand-held camera captures images using a focal-plane array based on gallium arsenide quantum-well IR photo detector (QWIP) technology. The image uniformity provided by the gallium arsenide detector can provide an advantage for some applications over the indium antimonide detectors that are also used in long-wavelength IR cameras, according to Charles Norris, a development engineer at Inframetrics. The gallium arsenide array is most sensitive--50% bandpass--between 8 and 9 µm and can detect from 7 to 9.2 µm at 10% pass, according to Sarath Gunapala at the JPL. Primary commercial applications for the device are expected to be in maintenance and troubleshooting applications, such as inspection of rail cars and power lines. Other possible applications for the long-wavelength IR device include detection of human activity in surveillance situations and astronomical detection of distant galactic objects. The device costs about $50,000 and can run on a camcorder battery for about three hours.
