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13 April 2000 Infrared vision using uncooled optomechanical camera
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Proceedings Volume 3948, Photodetectors: Materials and Devices V; (2000)
Event: Symposium on Integrated Optoelectronics, 2000, San Jose, CA, United States
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.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Arunava Majumdar, M. Mao, Thomas M. Perazzo, Yang Zhao, O. Kwon, John B. Varesi, and Paul Norton "Infrared vision using uncooled optomechanical camera", Proc. SPIE 3948, Photodetectors: Materials and Devices V, (13 April 2000);


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