Passive standoff detection of chemical vapors by differential FTIR radiometry


  1. Theriault, J-M.
Corporate Authors
Defence Research Establishment Valcartier, Valcartier QUE (CAN)
This report presents a novel method for the passive standoff detection of chemical vapors by differential radiometry. The originality of the method lies on the use of a double-input beam Fourier Transform Infrared (FTIR) interferometer optimized for optical subtraction. For implementating this method, a radiative transfer model is formulated for the general case of slant path scenarios containing any type of background scenes. A procedure of radiometric calibration adapted for differential detection with a double-input beam FTIR interferometer is developed. A detection algorithm (GASEM that controls the interferometer data acquisition and performs the on-line monitoring of chemical vapor parameters is described and validated. The differential detection method has been successfully tested in the field on several chemical vapors. In particular, it has been used to map the integrated concentration and the temperature of a plume of methanol vapor. In this case, the uncertainties on the methanol plume measurements have been estimated to be of the order of 15 to 30% for concentration, and 2 to 5 degrees for temperature which represents an acceptable result for this type of passive sensing.
Passive standoff detection;Chemical vapor monitoring;Chemical vapour monitoring;Differential detection;Double beam interferometer;Fourier Transform Infrared Spectroscopy;Chemical warfare agents;Indentification
Report Number
DREV-TR-2000-156 — Technical Report
Date of publication
01 Jan 2001
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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