Direct-view uncooled micro-optomechanical infrared camera

Abstract

This paper presents the design, fabrication, and the first imaging results of a new uncooled infrared (IR) camera based on thermomechanical sensing and a novel optical readout technique that directly interfaces with the human eye. The system contains a focal plane array (FPA) consisting of bimaterial cantilever beams in each pixel. Absorption of the incident IR radiation by each cantilever beam raises its temperature, resulting in proportional deflection due to mismatch in thermal expansion of the two cantilever materials. A visible optical system is used to simultaneously measure the deflections of all the cantilever beams of the FPA using either Fabry-Perot interferometry or deformable diffraction gratings, and collectively project a visible image of the spatially-varying IR radiation directly on the human eye. The camera is designed to be sensitive in the spectral range of 8-14 /spl mu/m which is key to night vision. The first results suggest that objects at temperatures as low as 100/spl deg/C can be imaged with the best noise-equivalent temperature difference (NE/spl Delta/T) in the range of 10 K. It is estimated that further improvements that are currently being pursued can improve NE/spl Delta/T to about 50 mK.