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Proceedings Paper

Stand-off detection of trace explosives by infrared photothermal imaging
Author(s): Michael R. Papantonakis; Chris Kendziora; Robert Furstenberg; Stanley V. Stepnowski; Matthew Rake; Jennifer Stepnowski; R. Andrew McGill
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Paper Abstract

We have developed a technique for the stand-off detection of trace explosives using infrared photothermal imaging. In this approach, infrared quantum cascade lasers tuned to strong vibrational absorption bands of the explosive particles illuminate a surface of interest, preferentially heating the explosives material. An infrared focal plane array is used to image the surface and detect a small increase in the thermal intensity upon laser illumination. We have demonstrated the technique using TNT and RDX residues at several meters of stand-off distance under laboratory conditions, while operating the lasers below the eye-safe intensity limit. Sensitivity to explosives traces as small as a single grain (~100 ng) of TNT has been demonstrated using an uncooled bolometer array. We show the viability of this approach on a variety of surfaces which transmit, reflect or absorb the infrared laser light and have a range of thermal conductivities. By varying the incident wavelength slightly, we demonstrate selectivity between TNT and RDX. Using a sequence of lasers at different wavelengths, we increase both sensitivity and selectivity while reducing the false alarm rate. At higher energy levels we also show it is possible to generate vapor from solid materials with inherently low vapor pressures.

Paper Details

Date Published: 8 May 2009
PDF: 9 pages
Proc. SPIE 7304, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing X, 730418 (8 May 2009); doi: 10.1117/12.818752
Show Author Affiliations
Michael R. Papantonakis, Naval Research Lab. (United States)
Chris Kendziora, Naval Research Lab. (United States)
Robert Furstenberg, Naval Research Lab. (United States)
National Research Council (United States)
Stanley V. Stepnowski, Naval Research Lab. (United States)
Matthew Rake, Nova Research, Inc. (United States)
Jennifer Stepnowski, Nova Research, Inc. (United States)
R. Andrew McGill, Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 7304:
Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing X
Augustus W. Fountain; Patrick J. Gardner, Editor(s)

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