Multispectral imaging Raman spectroscopy is a novel technique for detecting and identifying explosive residues, e.g.
explosives particles which are left on surfaces after handling or manufacturing of explosives.
By imaging a suspect surface using the imaging Raman technique, explosives particles at stand-off distances can be
identified and displayed using color coding1.
In this paper we present an attempt to determine a limit of detection for imaging Raman spectroscopy by analyzing holes
of various sizes in aluminum plates filled with four different substances; 2,4-dinitrotoulene (DNT), ammonium nitrate
(AN), sulfur, and 2,4,6-trinitrotoulene (TNT). The detection time in the presented experiments has not been optimized,
instead more effort has been invested in order to reduce false alarms. The detection system used is equipped with a green
second harmonic Nd:YAG laser with an average power of 2 W, a 200 mm telescope and a liquid crystal tunable filter to
scan the wavenumbers. The distance to the target was 10 m and the imaged area was 28 mm × 28 mm. The measured
multi-spectral data cubes were evaluated using least square fitting to distinguish between DNT, AN,S, TNT and the
background. The detection limit has been determined to be sub microgram using the current setup.