Demonstration of an uncooled LiTaO3-detector-based differential absorption radiometer for remote sensing of chemical effluents

Stephen Keith Holland; Roland H. Krauss; Gabriel Laufer

doi:10.1117/1.1782612

1 October 2004 Demonstration of an uncooled LiTaO₃-detector-based differential absorption radiometer for remote sensing of chemical effluents

Stephen Keith Holland, Roland H. Krauss, Gabriel Laufer

Author Affiliations +

Optical Engineering, Vol. 43, Issue 10, (October 2004). https://doi.org/10.1117/1.1782612

Abstract

Differential absorption radiometers (DARs) using uncooled detectors are introduced as a simple method for low-cost remote sensing of chemical vapors for domestic security. A DAR consisting of a pair of uncooled LiTaO₃ pyroelectric detectors integrated with bandpass filters selected to detect methanol, a simulant of many hazardous vapors, was demonstrated. At a signal-to-noise ratio (SNR) 5, the measured detection limit for methanol was 0.014 atm cm. This corresponds to a detection limit of 5.70×10^–4 atm cm (31.5 mg m^–2) for dimethyl methylphosphonate (DMMP). For comparison, a DAR consisting of a pair of cryogenically cooled HgCdTe (MCT) detectors was also tested. The detector-limited noise equivalent temperature differential (NETD) of the MCT detectors was measured to be 0.38 mK, whereas for the pyroelectric detector it was 115 mK. Despite the much lower detector noise, the MCT-based DAR provided a detection limit of only 0.005 atm cm for methanol, corresponding to 2.04×10^–4 atm cm (11.25 mg m^–2) for DMMP. The relatively poor sensitivity of the MCT-based DAR was shown to be limited by small temperature gradients of 15 mK across the noncoincident fields of view of the detectors in the DAR and by environmental fluctuations, which contributed a total NETD = 37 mK.

©(2004) Society of Photo-Optical Instrumentation Engineers (SPIE)

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Stephen Keith Holland, Roland H. Krauss, and Gabriel Laufer "Demonstration of an uncooled LiTaO₃-detector-based differential absorption radiometer for remote sensing of chemical effluents," Optical Engineering 43(10), (1 October 2004). https://doi.org/10.1117/1.1782612

Published: 1 October 2004

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