12 October 2010 Near-infrared spectroscopy for personal screening
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Abstract
This paper will demonstrate that near infrared (NIR) signals at wavelengths in the range 0.9 to 2.5 microns can be used for personal screening applications. At these wavelengths, there is sufficient spectral information to provide chemical identification, while still providing transmission through many types of common clothing materials. Thus, chemical identification in diffuse reflection is possible. Initial measurements on selected clothing materials have indicated that there is sufficient transmission to allow NIR spectra from concealed chemicals to be collected. The effect of the clothing material on the observed spectra has also been quantified. The clothing materials ranged from cotton to man-made fibres. Spectra have been collected at stand-off distances of several metres or more, using a suitable lens system and an NIR spectrometer. The optics required to achieve this will be described, and some spectra from chemicals hidden behind clothing will be presented. The further steps necessary to provide correct identification of chemicals such as ammonium nitrate in granular form will also be given, involving signal analysis methods. A set of spectra will be shown that have been collected and analysed, for a wide range of clothing fabric materials, indicating that the technique could have wide application to personal screening situations.
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Céline M. Canal, Céline M. Canal, Aamer Saleem, Aamer Saleem, Roger J. Green, Roger J. Green, David A. Hutchins, David A. Hutchins, } "Near-infrared spectroscopy for personal screening", Proc. SPIE 7838, Optics and Photonics for Counterterrorism and Crime Fighting VI and Optical Materials in Defence Systems Technology VII, 78380G (12 October 2010); doi: 10.1117/12.865831; https://doi.org/10.1117/12.865831
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