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Proceedings Paper

Towards eye-safe standoff Raman imaging systems
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Paper Abstract

Standoff Raman imaging systems have shown the ability to detect single explosives particles. However, in many cases, the laser intensities needed restrict the applications where they can be safely used. A new generation imaging Raman system has been developed based on a 355 nm UV laser that, in addition to eye safety, allows discrete and invisible measurements. Non-dangerous exposure levels for the eye are several orders of magnitude higher in UVA than in the visible range that previously has been used. The UV Raman system has been built based on an UV Fabry-Perot Interferometer (UV-FPI) developed by VTT. The design allows for precise selection of Raman shifts in combination with high out-of-band blocking. The stable operation of the UV-FPI module under varying environmental conditions is arranged by controlling the temperature of the module and using a closed loop control of the FPI air gap based on capacitive measurement. The system presented consists of a 3rd harmonics Nd:YAG laser with 1.5 W average output at 1000 Hz, a 200 mm Schmidt-Cassegrain telescope, UV-FPI filter and an ICCD camera for signal gating and detection. The design principal leads to a Raman spectrum in each image pixel. The system is designed for field use and easy manoeuvring. Preliminary results show that in measurements of <60 s on 10 m distance, single AN particles of <300 μm diameter can be identified.

Paper Details

Date Published: 29 May 2014
PDF: 11 pages
Proc. SPIE 9072, Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XIX, 907210 (29 May 2014); doi: 10.1117/12.2049676
Show Author Affiliations
Martin Glimtoft, FOI Swedish Defence Research Agency (Sweden)
Petra Bååth, FOI Swedish Defence Research Agency (Sweden)
Heikki Saari, VTT Technical Research Ctr. of Finland (Finland)
Jussi Mäkynen, VTT Technical Research Ctr. of Finland (Finland)
Antti Näsilä, VTT Technical Research Ctr. of Finland (Finland)
Henric Östmark, FOI Swedish Defence Research Agency (Sweden)


Published in SPIE Proceedings Vol. 9072:
Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XIX
Steven S. Bishop; Jason C. Isaacs, Editor(s)

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