Stand-off detection of trace explosives by infrared photothermal imaging
2009
We have developed a technique for the stand-off detection of trace explosives using infrared photothermal
imaging. In this approach, infrared quantum cascade lasers tuned to strong vibrational absorption bands of the explosive
particles illuminate a surface of interest, preferentially heating the explosives material. An infrared focal plane array is
used to image the surface and detect a small increase in the thermal intensity upon laser illumination. We have
demonstrated the technique using TNT and RDX residues at several meters of stand-off distance under laboratory
conditions, while operating the lasers below the eye-safe intensity limit. Sensitivity to explosives traces as small as a
single grain (~100 ng) of TNT has been demonstrated using an uncooled bolometer array. We show the viability of this
approach on a variety of surfaces which transmit, reflect or absorb the infrared laser light and have a range of thermal
conductivities. By varying the incident wavelength slightly, we demonstrate selectivity between TNT and RDX. Using
a sequence of lasers at different wavelengths, we increase both sensitivity and selectivity while reducing the false alarm
rate. At higher energy levels we also show it is possible to generate vapor from solid materials with inherently low
vapor pressures.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
0
References
15
Citations
NaN
KQI