One of the basic details for standoff sensing using infrared is that the back reflected. Intensity is extremely dependent on the alignment between the source, the target and the detector. In this study we considered the effect of having the source out of alignment at small to relatively large angular deviations from back reflection. The angle of the target with respect to the source and the detector was changed from 0� (back reflection) to 70�. The experiments were made using three infrared sources/modalities: Fourier transform infrared spectroscopy using a modulated source (MOD FT-IR), a non-modulated Globar (SiC) source (Non-MOD FT-IR) external to the interferometer and a dispersive scanning Quantum Cascade Laser based spectrometer and detector (QCL-IRS). The targets consisted of 200 to 5 mg/cm2PENT deposited on aluminum placed at 1 meter from the sources. The evaluation of the three modalities was aimed at verifying the influence of the highly collimated laser beam (QCL) in the detection in comparison with other sources.

Standoff detection by infrared spectroscopy: Dependence on the alignment and the excitation source

245th National Meeting (2013)

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