25 May 2016 QCL-based standoff and proximal chemical detectors
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Abstract
The development of two longwave infrared quantum cascade laser (QCL) based surface contaminant detection platforms supporting government programs will be discussed. The detection platforms utilize reflectance spectroscopy with application to optically thick and thin materials including solid and liquid phase chemical warfare agents, toxic industrial chemicals and materials, and explosives. Operation at standoff (10s of m) and proximal (1 m) ranges will be reviewed with consideration given to the spectral signatures contained in the specular and diffusely reflected components of the signal. The platforms comprise two variants: Variant 1 employs a spectrally tunable QCL source with a broadband imaging detector, and Variant 2 employs an ensemble of broadband QCLs with a spectrally selective detector. Each variant employs a version of the Adaptive Cosine Estimator for detection and discrimination in high clutter environments. Detection limits of 5 μg/cm2 have been achieved through speckle reduction methods enabling detector noise limited performance. Design considerations for QCL-based standoff and proximal surface contaminant detectors are discussed with specific emphasis on speckle-mitigated and detector noise limited performance sufficient for accurate detection and discrimination regardless of the surface coverage morphology or underlying surface reflectivity. Prototype sensors and developmental test results will be reviewed for a range of application scenarios. Future development and transition plans for the QCL-based surface detector platforms are discussed.
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Julia R. Dupuis, Joel Hensley, Bogdan R. Cosofret, Daisei Konno, Phillip Mulhall, Thomas Schmit, Shing Chang, Mark Allen, William J. Marinelli, "QCL-based standoff and proximal chemical detectors", Proc. SPIE 9836, Micro- and Nanotechnology Sensors, Systems, and Applications VIII, 98362F (25 May 2016); doi: 10.1117/12.2223038; https://doi.org/10.1117/12.2223038
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