Foreign and homegrown terrorism, illegal drug manufacture and environmental contamination, have lead to an increased need for rapid, portable and standoff chemical threat (explosives, narcotics, toxic industrial chemicals, etc.) detection technology. Analytical techniques; like High-Performance Liquid Chromatography (HPLC), Gas Chromatography-Mass Spectrometry (GC-MS), and Ion-Mobility Spectrometry (IMS), are industry standards due their unmatched combination of sensitivity and selectivity. However, samples must be handled by and handler and for analysis, putting the user at risk if samples are of a potentially threatening nature. Vibrational spectroscopic techniques are uniquely suited to this application as they offer chemical identification capabilities as well as the ability to be collected at standoff distances, as emitted or scattered photons are collected at some distance from the sample. Here we report on chemical threat detection instrumentation methods which employs deep ultra-violet (DUV) Raman spectroscopy and Light Detection And Ranging (LiDAR) imaging. UV Raman spectra were measured using a novel experimental configuration. This configuration allows many of the difficulties associated with UV excitation and high-power pulsed laser sources to be mitigated. Large sample areas are imaged into the detection system allowing high power excitation sources to be used while simultaneously avoiding sample degradation and multi-photon absorption effects. Such large detection areas allow large numbers of molecular scatters to be probed even with minimal penetration depth. Alignment issues between sample and collection optics are also simplified.
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