3 May 2010 Absolute temperature measurements using a two-color QWIP focal plane array
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Abstract
The infrared photon flux emitted by an object depends not only on its temperature but also on a proportionality factor referred to as its emissivity. Since the latter parameter is usually not known quantitatively a priori, any temperature determination based on single-band radiometric measurements suffers from an inherent uncertainty. Recording photon fluxes in two separate spectral bands can in principle circumvent this limitation. The technique amounts to solving a system of two equations in two unknowns, namely, temperature and emissivity. The temperature derived in this manner can be considered absolute in the sense that it is independent of the emissivity, as long as that emissivity is the same in both bands. QmagiQ has previously developed a 320x256 midwave/longwave staring focal plane array which has been packaged into a dual-band laboratory camera. The camera in question constitutes a natural tool to generate simultaneous and independent emissivity maps and temperature maps of entire two-dimensional scenes, rather than at a single point on an object of interest. We describe a series of measurements we have performed on a variety of targets of different emissivities and temperatures. We examine various factors that affect the accuracy of the technique. They include the influence of the ambient radiation reflected off the target, which must be properly accounted for and subtracted from the collected signal in order to lead to the true target temperature. We also quantify the consequences of spectrally varying emissivities.
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Jason Bundas, Jason Bundas, Richard Dennis, Richard Dennis, Kelly Patnaude, Kelly Patnaude, Douglas Burrows, Douglas Burrows, Ross Faska, Ross Faska, Mani Sundaram, Mani Sundaram, Axel Reisinger, Axel Reisinger, Dan Manitakos, Dan Manitakos, } "Absolute temperature measurements using a two-color QWIP focal plane array", Proc. SPIE 7660, Infrared Technology and Applications XXXVI, 76603R (3 May 2010); doi: 10.1117/12.852628; https://doi.org/10.1117/12.852628
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