Standoff infrared detection of explosives at laboratory scale

Abstract

An actively operated standoff infrared detection system was designed from commercial infrared equipment: VECTOR 22 FTIR (Bruker Optics), an external mirror and an external MCT detector. One type of experiment was done for IR detection of high explosives RDX and TNT on reflective surfaces. In the detection on surface, the samples were move to different distances and a beam of infrared light was reflect on surface in angle of ~ 0° (backward collection from surface normal). First the samples: 2 to 30 μg/cm² of high explosives TNT and RDX were characterized after depositing on stainless steel reflective surfaces using Reflection-Absorption Infrared Spectroscopy (RAIS). Then targets were moved to increasing distances: 3 to 12 feet and remote-sensed spectra were collected in active reflectance mode. The limits of detection were determined for all distances measured in both nitroexplosives. Limit of detection of 18 and 20 μg/cm² for TNT and RDX respectively in the longest distances measured.