Washington, June 2 : Scientists at the Center for Quantum Devices (CQD) in the McCormick School of Engineering at Northwestern University have invented a high-performance infrared imager that looks at wavelengths 20 times longer than visible light.
The researchers revealed that their imager was based on a Type II superlattice.
Lead researcher Manijeh Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science, said that the new technology could revolutionise the detection of terrorist activities-like use in night vision, target identification, and missile tracking.
The researchers said that the idea was based on the fact that any object, including the human body, with a near-room temperature actively emits long wavelength (around 10 micron) infrared radiation (LWIR).
If tracked with the aid of high-speed infrared (IR) imagers, added the researcher, such infrared radiations might help reveal thermal profiles of hidden targets or objects at night when no visible source is available.
Razeghi said that such imagers might also help revolutionise medical applications, as excessive heating or cooling in the body could facilitate the diagnosis of inflammation, blood flow issues or even cancerous tissue.
In LWIR imaging applications, the dominant technologies are photodetectors based upon the HgCdTe (mercury cadmium telluride or MCT) material platform and the quantum well photoconductors (QWIP), both of which have shown limitations that stimulated the research for alternative technologies.
Type-II superlattices, first proposed by Nobel laureate Leo Esaki in 1973, became a potential for use in infrared detection in 1987.
"The type-II superlattice will become the next generation infrared material replacing MCT technology. MCT has many limitations, especially in the longer wavelength infrared range critical for missile detection," Science Daily quoted Razeghi as saying.
Razeghi's team recently announced the creation of a new superlattice structure, called the M-structure, which further improved the performance of the type II superlattice.
The new device was capable of detecting very low light intensity with high optical efficiency, and showed an electrical noise level 10 times smaller than the original design..
The camera had the ability to detect 74 per cent of the incident photons, similar to other leading technologies.
A presentation on that innovation was made at the SPIE Photonics West Conference held in San Jose, CA on Jan. 19-24, 2008.
The research project was also reported in the journal Applied Physics Letters.