Infrared Vision Using an Uncooled Thermo-opto-mechanical Camera; Design, Microfabrication, and Performance

M. Mao, T. Perazzo, O. Kwon, Y. Zhao, A. Majumdar, J. Varesi, P. Norton

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

An uncooled infrared (IR) camera that is based on thermomechanical sensing and 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 of incident IR radiation in the 8-14 μm 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. To maximize the thermal performance, the conductance of each pixel was reduced to about five times of the radiation conductance. Based on thermomechanical analysis, the geometrical shape of the pixels were designed to maximize the cantilever sensitivity within the constraints of the pixel size and layout. 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 design of each pixel was based on IR properties of the cantilever materials, IR absorption enhancement due to resonance cavity formation, as well as visible optics of deformable diffraction gratings. The latter formed the foundation for two different optical readout techniques that were both used for IR imaging. The results suggest that objects at temperatures as low as 30'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 pursued can improve NETD to about 10 mK.

Original languageEnglish
Title of host publicationMicro-Electro-Mechanical Systems (MEMS)
PublisherAmerican Society of Mechanical Engineers (ASME)
Pages309-316
Number of pages8
ISBN (Electronic)9780791816387
DOIs
Publication statusPublished - 1999
Externally publishedYes
EventASME 1999 International Mechanical Engineering Congress and Exposition, IMECE 1999 - Nashville, United States
Duration: 1999 Nov 141999 Nov 19

Publication series

NameASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
Volume1999-W

Conference

ConferenceASME 1999 International Mechanical Engineering Congress and Exposition, IMECE 1999
Country/TerritoryUnited States
CityNashville
Period99/11/1499/11/19

ASJC Scopus subject areas

  • Mechanical Engineering

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