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Proceedings Paper

Infrared vision using uncooled optomechanical camera
Author(s): Arunava Majumdar; M. Mao; Thomas M. Perazzo; Yang Zhao; O. Kwon; John B. Varesi; Paul Norton
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Paper Abstract

An uncooled IR imaging system that is based on thermomechanical sensing of IR radiation in conjunction with a visible optical readout has been developed. The system contains a focal plane array (FPA) consisting of bimaterial cantilever beams made of silicon nitride (SiNx) and gold (Au) in each pixel. Absorption on incident IR radiation in the 8-14 micrometers wavelength range by SiNx in each cantilever beam raises its temperature, resulting in proportional deflection due to mismatch in thermal expansion of the two cantilever materials. The FPA design involved maximizing the thermal resistance between the pixel and its surroundings, maximizing the thermomechanical response within the constraints of the pixel size, optimizing the pixel time response, and maximizing the IR absorption using thin film optics. Microfabrication of stress-balanced bimaterial cantilevers was achieved by varying the silicon concentration along the thickness of the SiNx films in order to balance the residual tensile stress in the Au film and the Cr adhesion layer between Au and SiNx. The optical readout utilized Fourier diffractive optics to simultaneously detect deflections of all cantilevers using a single light source. The results suggest that objects at temperatures as low as 30 degrees C can be imaged with the best noise-equivalent temperature difference (NETD) in the range of 2-5 K. It is estimated that further improvements that are currently being pursed can improved NETD below 5 mK.

Paper Details

Date Published: 13 April 2000
PDF: 6 pages
Proc. SPIE 3948, Photodetectors: Materials and Devices V, (13 April 2000); doi: 10.1117/12.382146
Show Author Affiliations
Arunava Majumdar, Univ. of California/Berkeley (United States)
M. Mao, Univ. of California/Berkeley (United States)
Thomas M. Perazzo, Univ. of California/Berkeley (United States)
Yang Zhao, Univ. of California/Berkeley (United States)
O. Kwon, Univ. of California/Berkeley (United States)
John B. Varesi, Raytheon Co. (United States)
Paul Norton, Raytheon Co. (United States)

Published in SPIE Proceedings Vol. 3948:
Photodetectors: Materials and Devices V
Gail J. Brown; Manijeh Razeghi, Editor(s)

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