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Proceedings Paper

Gas imaging with wavelength modulation spectroscopy and a micromirror array
Author(s): Chris Hovde; Shin-Juh Chen; Kristen A. Peterson; Mark Paige
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Paper Abstract

Backscatter gas imaging uses laser absorption spectroscopy to detect the presence of a gas by illuminating a region with light from an infrared laser and imaging the returned light. Contrast can be enhanced by comparing the back-scattered intensity on and off the absorption feature. Wavelength modulation spectroscopy can provide just such a capability, but the detector signal must be processed with a lock-in amplifier, which is incompatible or prohibitively expensive with most array detectors. Images can be recorded using a single photodiode by spatially modulating the laser or the detected image. This paper describes initial experiments to demonstrate the feasibility of a combined wavelength- and spatially- modulated gas imager. It is based on a single near-infrared laser, a single detector, lock-in detection, and a commercial micromirror array. The gases imaged include water vapor, mono-deuterated water vapor, acetylene and hydrogen cyanide. Doppler imaging is demonstrated using heterodyne detection and spatial image modulation.

Paper Details

Date Published: 4 November 2005
PDF: 7 pages
Proc. SPIE 5995, Chemical and Biological Standoff Detection III, 59950I (4 November 2005); doi: 10.1117/12.630770
Show Author Affiliations
Chris Hovde, Southwest Sciences, Inc. (United States)
Shin-Juh Chen, Southwest Sciences, Inc. (United States)
Kristen A. Peterson, Southwest Sciences, Inc. (United States)
Mark Paige, Southwest Sciences, Inc. (United States)

Published in SPIE Proceedings Vol. 5995:
Chemical and Biological Standoff Detection III
James O. Jensen; Jean-Marc Thériault, Editor(s)

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