Superlattice Cameras Add Color To Night Vision Images. Evanston, IL – In addition to its recent development of a narrow-band terahertz source, Manijeh Razeghi Northwestern University group Center for Quantum Devices have built an infrared camera that can see more of an optical frequency band “color” in the dark. The semiconductor material used in the device – a type II superlattice – can be adjusted to accommodate a wide range of infrared wavelengths, and now a number of different infrared bands simultaneously.
The idea of capturing light simultaneously at different wavelengths is not new. Digital cameras in the visible spectrum are usually equipped with sensors that perceive red, green and blue to play most of the colors perceived by the human eye. Multi-color detection in the infrared spectrum, however, offers unique features beyond the color representation. The resonance frequencies of the compounds often found in this spectral range, which means that chemical spectroscopy can be transmitted in real time images.
“When combined with image processing algorithms run on multiple frequency bands, the amount of information that is disclosed in a particular scene is huge,” said Manijeh Razeghi, Walter P. Murphy Professor of Engineering Electrical and Computer McCormick School of Engineering and director of the Center for Quantum Devices.
Razeghi group manipulated the energy detection cameras to be extremely narrow, close to a tenth of an electron volt, in what is known as the long-wave infrared window. Creation of cameras, however, was difficult because the light-absorbing layer is prone to interference effects. In addition, sensors designed to be stacked, which provided the registration area coincides pixel, but added significantly to the growth and manufacturing challenges. However, a long wavelength infrared dual-band support 320-256 type II has been shown superlattice camera for the first time in the world, whose results were published in July 2011 Issue of Optics Letters.
Although the cameras with IR photon of mercury telluride (HgCdTe) were used to alleviate the disaster in March 2011, when the tsunami disaster damaged Japans’ nuclear reactors, HgCdTe is an expensive technology for long-wave infrared because of its poor spectral uniformity and thus revenue – areas in which the type II superlattices can be more efficient.