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Abstract: Passive infrared imaging sensor for standoff detection of methane leaks
B.R. Cosofret, W.J. Marinelli, T. Ustun, C.M. Gittins, M.T. Boies, M.F. Hinds, D.C. Rossi, R. Coxe, S. Chang,
"Passive infrared imaging sensor for standoff detection of methane leaks
,"
presented at SPIE Optics East Chemical and Biological Standoff Detection II
(Philadelphia, PA)
,
(25-28 October2004).
Copyright © 2004 Society of Photo-Optical Instrumentation Engineers.
This paper was published in SPIE Optics East Chemical and Biological Standoff Detection II,
and is made available as an electronic reprint (preprint)
with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple
reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this
paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
Abstract
Physical Sciences Inc. (PSI) has developed an imaging sensor for remote detection of natural gas (methane) leaks. The sensor is comprised of an IR focal plane array-based camera which views the far field through a rapidly tunable Fabry-Perot interferometer. The interferometer functions as a wavelength-variable bandpass filter which selects the wavelength illuminating the focal plane array. The sensor generates 128 pixel x 128 pixel methane images with aspatial resolution of 1 m >100 x 100 pixel field-of-view. The methane column density at each pixel in the image is calculated in real time using an algorithm which estimates and compensates for line-of-sight atmospheric transmission. The compensation algorithm incorporates range-to-target as well as local air temperature and humidity. System testsconducted at 200 m standoff from sensor to leak location indicate probability of detection >90% for methane column densities >1000 ppmv-m and >2K thermal contrast between the air and the background. The probability of false alarm is less than 0.2% under these detection conditions.
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