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Publication Citation: Absorption, transmission, and scattering of expanded polystyrene at millimeter-wave and terahertz frequencies

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Author(s): Charles Dietlein; Jon E. Bjarnason; Erich N. Grossman; Zoya Popovic;
Title: Absorption, transmission, and scattering of expanded polystyrene at millimeter-wave and terahertz frequencies
Published: March 17, 2008
Abstract: Conventional material measurements of transmission and reflection in the millimeter-wave and terahertz frequency range do not differentiate between scattering and absorption, grouping effects from both mechanisms together into 'loss'. Accurate knowledge of the balance between scattering and absorption is critical in applications such as radiometric scene modeling for concealed object detection, where evaluation of object detectability depends strongly on the amount of scattering due to concealers such as clothing. We describe an experimental setup for the measurement of spatial bidirectional reflectance distribution function (BRDF). Previous measurements have shown extremely low-level grating lobes from periodic clothing materials such as corduroy, around 30 dB below the transmitted beam. To adequately address this issue of high dynamic range, we utilize a cryogenic antenna-coupled microbolometer for detection. We present data on several types of expanded polystyrene, a common structural material for systems and experiments in this frequency range. In these measurements of BRDF, transmission agrees with previous measurements, and the balance between low and high angle scattering, specular reflectance, and absorption is examined.
Conference: SPIE - The International Society for Optical Engineering, Defense & Security Symposium
Proceedings: Proc. of SPIE
Volume: Vol. 6948
Pages: pp. 69480E-1 - 69480E-9
Location: Orlando, FL
Dates: March 17-20, 2008
Keywords: scattering; terahertz; BRDF; millimeter-wave; material measurement; absorption; expanded polystyrene
Research Areas: Electronics & Telecommunications, Optoelectronics, Terahertz Technology
PDF version: PDF Document Click here to retrieve PDF version of paper (589KB)