8 October 2007 Diffuse reflection imaging at terahertz frequencies for security applications
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We report diffuse reflection imaging of concealed powdered samples in atmospheric air using a quantum cascade laser operating at 2.83 THz. The imaging system uses a helium-cooled silicon bolometer for mapping radiation diffusely reflected and scattered from samples, and a room-temperature pyroelectric sensor for simultaneously acquiring a specular image. A range of powders concealed within plastic packaging and standard FedEx envelopes was imaged with a resolution of better than 0.5 mm, and it was possible to detect powdered samples concealed within packaging from which there was a strong component of surface reflection. The feasibility of performing dual-wavelength diffuse reflection imaging for identification of illicit drugs and explosives is discussed.
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P. Dean, P. Dean, S. Khanna, S. Khanna, S. Chakraborty, S. Chakraborty, M. Lachab, M. Lachab, A. G. Davies, A. G. Davies, E. H. Linfield, E. H. Linfield, "Diffuse reflection imaging at terahertz frequencies for security applications", Proc. SPIE 6741, Optics and Photonics for Counterterrorism and Crime Fighting III, 67410R (8 October 2007); doi: 10.1117/12.739281; https://doi.org/10.1117/12.739281

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