Modeling of laser-analyte-substrate interaction in photo-thermal infrared imaging and laser trace vaporization

Robert Furstenberg; Jakob Großer; Christopher A. Kendziora; Michael R. Papantonakis; Viet Nguyen; R. Andrew McGill

doi:10.1117/12.883471

10 May 2011 Modeling of laser-analyte-substrate interaction in photo-thermal infrared imaging and laser trace vaporization

Robert Furstenberg, Jakob Großer, Christopher A. Kendziora, Michael R. Papantonakis, Viet Nguyen, R. Andrew McGill

Author Affiliations +

Proceedings Volume 8013, Thermosense: Thermal Infrared Applications XXXIII; 801318 (2011) https://doi.org/10.1117/12.883471
Event: SPIE Defense, Security, and Sensing, 2011, Orlando, Florida, United States

Abstract

We are developing two techniques for non-contact detection of explosives and other substances with low vapor pressure. In one approach, quantum cascade lasers (QCLs) at eye-safe power levels heat trace residues on surfaces at stand-off distances and the photo-thermal signal is imaged with an infrared camera. When using wavelengths corresponding to vibrational resonances specific to the trace molecules, the traces can be selectively heated and become visible in the infrared. In a second approach, a QCL or other IR laser of higher power is used to enhance the vapor signature of the analyte, thus facilitating vapor-based (e.g. ion mobility spectrometry) techniques. Details and advances in these techniques will be reported elsewhere. In this paper, we study the laser heating of analytes on substrates using the simulation software COMSOL. A model is validated with experimental results for particles of well characterized shape and size. The heat transfer between particle and substrate is of special interest, but not necessarily the dominant contributor to heat loss. Both air- and substrate-mediated heating of neighboring interferent particles is generally negligible. The presence of neighboring explosives particles affects the thermal kinetics via air-mediated heat transfer.

Citation Download Citation

Robert Furstenberg, Jakob Großer, Christopher A. Kendziora, Michael R. Papantonakis, Viet Nguyen, and R. Andrew McGill "Modeling of laser-analyte-substrate interaction in photo-thermal infrared imaging and laser trace vaporization", Proc. SPIE 8013, Thermosense: Thermal Infrared Applications XXXIII, 801318 (10 May 2011); https://doi.org/10.1117/12.883471

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