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Absorption-sensitive diffuse reflection imaging of concealed powders using a terahertz quantum cascade laser

P. Dean, M. U. Shaukat, S. Khanna, S. Chakraborty, M. Lachab, A. Burnett, G. Davies, E. Linfield

Optics Express, 2008

52 citations

Abstract

We report diffuse reflection imaging in air of concealed powdered samples using a terahertz quantum cascade laser. The sensitivity of the detection scheme to sub-surface absorption within samples is confirmed using fully-characterized powdered admixtures of polystyrene and polymethyl methacrylate (PMMA). Measurements of the backscattering intensity from these samples are then used in conjunction with Kubelka-Munk scattering theory, as well as several models based on the quasi-crystalline approximation, to extract the absorption coefficient of PMMA. Our research demonstrates the feasibility of high-resolution frequency-domain terahertz imaging for the detection and identification of concealed powders in a reflection geometry.

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