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Proceedings Paper

Algorithms for chemical detection with a low-cost multi-spectral sensor
Author(s): Gregory C. Lewin; Stephen K. Holland; Gabriel Laufer
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Paper Abstract

A 16-channel, cross-reactive remote infrared chemical sensor for detection of toxic industrial chemicals in fixed-location applications is being developed. The outputs of the 16 channels, uncooled pyroelectric detectors fitted with infrared bandpass filters, can be viewed as a coarse spectrum of the chemical(s) in the field of view. This spectrum must be unmixed, wherein the identity and optical depth of the chemical(s) are estimated by processing the spectrum with a library of known signatures for the chemical(s) of interest. Several unmixing methods are presented, including enhancements to linear projection methods, parameterization (curve fitting) of the system response, and non-linear, iterative techniques. It is found that linear methods and simple curve parameterizations produce excessive unmixing errors. Higher-order parameterization and iterative methods provide much better estimates, with the latter being more computationally intensive. The suitability of the methods for the application at hand is discussed.

Paper Details

Date Published: 20 May 2005
PDF: 10 pages
Proc. SPIE 5778, Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense IV, (20 May 2005); doi: 10.1117/12.606712
Show Author Affiliations
Gregory C. Lewin, Avir, LLC (United States)
Stephen K. Holland, Univ. of Virginia (United States)
Gabriel Laufer, Univ. of Virginia (United States)


Published in SPIE Proceedings Vol. 5778:
Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense IV
Edward M. Carapezza, Editor(s)

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