Towards eye-safe standoff Raman imaging systems

Martin Glimtoft, Petra Bååth, Heikki Saari, Jussi Mäkynen, Antti Näsilä, Henric Östmark

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    14 Citations (Scopus)


    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.
    Original languageEnglish
    Title of host publicationProceedings of SPIE
    Subtitle of host publicationVolume 9072, Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XIX, 2014
    PublisherInternational Society for Optics and Photonics SPIE
    Number of pages11
    ISBN (Print)978-1-6284-1009-9
    Publication statusPublished - 2014
    MoE publication typeA4 Article in a conference publication
    EventSPIE Defense + Security - Baltimore, Maryland, United States
    Duration: 5 May 20149 May 2014

    Publication series

    SeriesProceedings of SPIE


    ConferenceSPIE Defense + Security
    Country/TerritoryUnited States
    CityBaltimore, Maryland


    • hyperspectral sensors
    • Raman imaging
    • Fabry-Perot interferometer
    • Piezo actuators


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