Infrared vision using uncooled micro-optomechanical camera

Abstract

This letter presents the design, fabrication, and imaging results of an uncooled infrared (IR) camera that contains a focal plane array of bimaterial microcantilever sensors, and an optical readout technique that measures cantilever deflections in the nanometer range to directly project a visible image of the IR scene on the human eye or a visible camera. The results suggest that objects at temperatures as low as 100 °C can be imaged with the best noise-equivalent temperature difference (NEΔT) in the range of 10 K. It is estimated that further improvements that are currently being pursued can improve NEΔT to about 50 mK.

Microthermomechanical infrared sensors

“…of Califor− nia, Berkeley) in 1999 [22]. The cantilever was made from LPCVD silicon nitride (SiN x ) and gold, had a complex fin− ger−geometry, used for deformable diffraction grating of the optical readout.…”

“…The first real−time thermal image captured with an optically read FPA has been reported by the Berkeley group in 1999 [22], with activities commencing in 1995 [46]. In the years between 1999 and 2003, patents and significant work have been reported on the optimization of the entire system [47][48][49][50][51][52].…”

Novel uncooled infrared detectors

“…Between them, the most important are bimaterial microcantilevers that mechanically respond to the absorp− tion of the radiation. These sensing structures were origi− nally invented at the Oak National Laboratory (ORNL) in the mid 1990's [11][12][13][14][15], and subsequently developed by ONRL [16][17][18][19][20], the Sarnoff Corporation [21,22], Sarcon Microsystems [23][24][25] and other for imaging [26][27][28][29][30][31][32][33] and photo spectroscopic applications [34,35].…”

“…In dependence on readout techniques, the novel uncooled detectors can be devoted on: [13,15,17,19,20,[26][27][28][30][31][32][33], l piezoresistive [11,12], and l electron tunnelling [8]. …”

Enhancing the Responsivity of Uncooled Infrared Detectors Using Plasmonics for High-Performance Infrared Spectroscopy

“…For example, bimetallic microcantilevers with absorptive coatings have been exploited as ultrasensitive thermal sensors for uncooled IR detection and imaging [5,7,8,9]. However, these microcantilever structure based IR detectors are very susceptible to intrinsic mechanical stresses, external vibrations, and ambient temperature fluctuations.…”