14 Apr 2005
Scientists investigate the environmental impact of Africa’s vegetation burning with the first-ever four-band infrared camera.
A collaboration between NASA’s Jet Propulsion Laboratory (JPL) and IQE claims to have produced the world’s first four-band infrared camera.
Based on quantum-well infrared photodetector (QWIP) technology, the camera is suitable for applications including weather prediction and remote sensing of pollution, such as the detection of nitrous oxide in smog. It has already been used as part of an international project investigating the environmental impact of vegetation burning and related ecological effects in Africa.
The camera’s four QWIP channels allow detection of radiation at wavelengths of 3-5 µm, 8-10 µm, 10-12 µm and 13.5-15.5 µm, and combine to give a pixel resolution of 640 by 512.
“This technology will revolutionize the way we develop new remote sensing instruments,” said JPL senior scientist Sarath Gunapala. “One such example is the detection of smog. Smog contains a range of chemicals which only appear in certain infrared ranges. The multi-band capacity of the camera array will allow researchers a full spectral view to identify them.”
Other technologies, such as microbolometer- and HgCdTe-based cameras, are more limited in terms of their spatial resolution, while HgCdTe cannot detect beyond 12 µm.
The QWIP camera contains GaAs-based material that was grown at IQE’s US facility, located in Bethlehem, PA. Infrared light excites carriers within the wells, which are then accelerated by an electric field to generate a photocurrent.
The detector will also be used to form the basis of a hyperspectral infrared camera, which may comprise over 64 wavelength bands. The project is a joint effort between JPL, IQE and the US Army Research Laboratory, and will contain quantum well structures fabricated on 6 inch GaAs substrates.