16 May 2018 Mid-infrared reflection signatures for trace chemicals on surfaces
Author Affiliations +
Results are presented for the detection of trace explosive residues on real-world surfaces using active mid-infrared (MIR) hyperspectral imaging. The target surface is illuminated using miniature, rapidly tunable, external-cavity quantum cascade lasers (EC-QCLs) and the reflected light is imaged using a HgCdTe camera with a spatial resolution of 70 μm. Hypercubes with 128x128 pixels are captured with more than 256 wavelengths that span 7.7 – 11.8 μm. The samples consisted of PETN residues which were applied to keyboard keys at various levels of chemical loading. We estimate a limit of detection of less than 6 ng per pixel for the as-deposited chemical. The explosive residue remains detectable by HSI even after wiping the surface several times using isopropyl alcohol. Simple signature models for solid particles (i.e., Mie scattering) and thin-films account for the many of the spectral features observed in the chemical signatures.
Conference Presentation
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Derek Wood, Derek Wood, David B. Kelley, David B. Kelley, Anish K. Goyal, Anish K. Goyal, Petros Kotidis, Petros Kotidis, } "Mid-infrared reflection signatures for trace chemicals on surfaces", Proc. SPIE 10629, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XIX, 1062915 (16 May 2018); doi: 10.1117/12.2304453; https://doi.org/10.1117/12.2304453

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