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Proceedings Paper

Remote detection of natural gas clouds in open fields by IR imagery
Author(s): Philippe Bernascolle; Gerard Pelous; Laurence Grenier
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Paper Abstract

The presented system is based upon a differential imaging radiometry technique, differential in both spectral and spatial domains: (1) The observation of a scene, acting as an infrared complex source is realized through a set of wide band filters: (A) a 'reference' filter, the transmission of which is located outside the absorption (or emission) features of the gas of interest: the resulting picture characterizes the scene background. (B) a 'measure' filter, the transmission of which incudes the absorption or emission bands of the gas of interest while remaining as close as possible to the 'reference' filter. The use of such filters, characterized by a high IR transmission over a wide wavelength band unlike the conventional radiometric methods, preserves the imaging function of the infrared camera. (2) A specific treatment is applied to the resulting pictures. Its originality consists in that gas concentration is not directly computed from the received IR flux, but from the image contrast variations between the two filtered images. In this way, the emission flux of gas cloud can be eliminated. Finally, the comparison of the 'contrast' images gives an absolute and quantitative measurement of gas concentration of the cloud integrated along the line of sight, whatever the respective temperatures of the gas cloud and the background scene are. A first generation demonstrator based on 8 - 12 micrometer commercial radiometric camera, and integrating a quasi-real time processing software, was tested on several gas, both in closed chamber and in open field. This paper presents an overview of the measurement technique and natural gas cloud measurement in atmosphere.

Paper Details

Date Published: 19 March 1999
PDF: 8 pages
Proc. SPIE 3700, Thermosense XXI, (19 March 1999); doi: 10.1117/12.342309
Show Author Affiliations
Philippe Bernascolle, Bertin (France)
Gerard Pelous, Bertin (France)
Laurence Grenier, Bertin (France)

Published in SPIE Proceedings Vol. 3700:
Thermosense XXI
Dennis H. LeMieux; John R. Snell, Editor(s)

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