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4 May 2012 Use of a spectroscopic lidar for standoff explosives detection through Raman spectra
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This paper assesses the potential of detecting explosives (RDX, TNT, PETN, HMX, HMTD, Urea Nitrate) from a distance with a spectroscopic lidar system. For the study, the temporal and spectral resolutions of laser induced fluorescence lidar prototypes were enhanced. The integrated breadboards used easily available Nd:YAG laser wavelengths (266 nm, 355 nm, and 532 nm) to remotely detect the Raman signatures induced in traces of explosives deposited on surfaces. The spectroscopic lidar setup allows for time resolved measurements with high temporal resolution. Raman spectra are observable, even in the presence of fluorescence. Experiments with low average laser power (tens of mWs) have shown the unambiguous capability to detect and identify explosives at distances ranging up to 20 m. Thanks to the combination of UV wavelength for higher Raman cross-sections and efficient gated detection the 355 nm prototype yielded the best compromise. Excitation at 266 nm was expected to yield a better Raman response and was investigated. Less than optimal laser parameters, detection efficiency and strong fluorescence reduced the signal to noise ratio of the 266 nm signals with respect to those at 355 nm and 532 nm showing the importance of optimizing system parameters for high sensitivity detection. Besides the description of the prototypes and an early assessment of their performances, recommendations are also proposed to improve the instrument, leading to an efficient remote sensor for explosives.
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Rosalie Forest, François Babin, David Gay, Nicolas Hô, Ovidiu Pancrati, Simon Deblois, Sylvain Désilets, and Jean Maheux "Use of a spectroscopic lidar for standoff explosives detection through Raman spectra", Proc. SPIE 8358, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XIII, 83580M (4 May 2012);

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