Imaging standoff detection of explosives using widely tunable midinfrared quantum cascade lasers

摘要

Abstract. The use of a tunable midinfrared external cavity quantumncascade laser for the standoff detection of explosives at medium dis-ntances between 2 and 5 m is presented. For the collection of the diffuselynbackscattered light, a high-performance infrared imager was used. Illumi-nnation and wavelength tuning of the laser source was synchronized withnthe image acquisition, establishing a hyperspectral data cube. Samplingnof the backscattered radiation from the test samples was performed in annoncooperative geometry at angles of incidence far away from specularnreflection. We show sensitive detection of traces of trinitrotoluene andnpentaerythritol tetranitrate on real-world materials, such as standard carnpaint, polyacrylics from backpacks, and jeans fabric. Concentrations cor-nresponding to fingerprints were detected, while concepts for false alarmnsuppression due to cross-contaminations were presented. C u00022010 Society ofnPhoto-Optical Instrumentation Engineers. [DOI: 10.1117/1.3506195]