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Proceedings Paper

Continuous-wave deep ultraviolet sources for resonance Raman explosive sensing
Author(s): Balakishore Yellampalle; Robert Martin; Mikhail Sluch; William McCormick; Robert Ice; Brian Lemoff
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Paper Abstract

A promising approach to stand-off detection of explosive traces is using resonance Raman spectroscopy with Deepultraviolet (DUV) light. The DUV region offers two main advantages: strong explosive signatures due to resonant and λ- 4 enhancement of Raman cross-section, and lack of fluorescence and solar background. For DUV Raman spectroscopy, continuous-wave (CW) or quasi-CW lasers are preferable to high peak powered pulsed lasers because Raman saturation phenomena and sample damage can be avoided. In this work we present a very compact DUV source that produces greater than 1 mw of CW optical power. The source has high optical-to-optical conversion efficiency, greater than 5 %, as it is based on second harmonic generation (SHG) of a blue/green laser source using a nonlinear crystal placed in an external resonant enhancement cavity. The laser system is extremely compact, lightweight, and can be battery powered. Using two such sources, one each at 236.5 nm and 257.5 nm, we are building a second generation explosive detection system called Dual-Excitation-Wavelength Resonance-Raman Detector (DEWRRED-II). The DEWRRED-II system also includes a compact dual-band high throughput DUV spectrometer, and a highly-sensitive detection algorithm. The DEWRRED technique exploits the DUV excitation wavelength dependence of Raman signal strength, arising from complex interplay of resonant enhancement, self-absorption and laser penetration depth. We show sensor measurements from explosives/precursor materials at different standoff distances.

Paper Details

Date Published: 20 May 2015
PDF: 8 pages
Proc. SPIE 9466, Laser Technology for Defense and Security XI, 946603 (20 May 2015); doi: 10.1117/12.2176672
Show Author Affiliations
Balakishore Yellampalle, West Virginia High Technology Consortium Foundation (United States)
Robert Martin, West Virginia High Technology Consortium Foundation (United States)
Mikhail Sluch, West Virginia High Technology Consortium Foundation (United States)
William McCormick, West Virginia High Technology Consortium Foundation (United States)
Robert Ice, West Virginia High Technology Consortium Foundation (United States)
Brian Lemoff, West Virginia High Technology Consortium Foundation (United States)


Published in SPIE Proceedings Vol. 9466:
Laser Technology for Defense and Security XI
Mark Dubinskii; Stephen G. Post, Editor(s)

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