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Proceedings Paper

The optical properties of biological tissues in the terahertz wavelength range
Author(s): Gerald J. Wilmink; Benjamin D Rivest; Bennett L. Ibey; Luisiana X. Cundin; Eric C Haywood; William P. Roach
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Paper Abstract

The terahertz (THz) region of the electromagnetic (EM) spectrum is defined as frequencies ranging from 0.1 to 10 THz. The optical properties of biological tissues have been characterized in neighboring spectral regions; however, few studies have been conducted that have examined these properties in the THz wavelength range. In this study, we used a far-infrared optically-pumped terahertz laser system, a reflection spectrometer system, and photothermal radiometric techniques to characterize the optical properties of water and biological tissues. The reflection spectrometer system performed well at lower frequencies, but proved to be unsuitable for frequencies greater than 2.52 THz. The suboptimal performance was determined to be primarily due to the higher transmission losses of the lenses, and the increased atmospheric losses that are associated with higher terahertz frequencies. The waveguide studies corroborated these findings and served to demonstrate that purging the laser beam path with nitrogen gas was an effective way to markedly reduce THz beam propagation losses. Given this finding, we have designed a temperature-controlled, nitrogen gas purged THz enclosure. The preliminary studies using photothermal radiometric techniques appeared to provide reasonable measures for the absorption coefficient (μa) of water at THz frequencies. In future studies, the tissue property measurements will made within the custom-designed enclosure using photothermal radiometric techniques.

Paper Details

Date Published: 24 February 2009
PDF: 8 pages
Proc. SPIE 7175, Optical Interactions with Tissue and Cells XX, 717507 (24 February 2009); doi: 10.1117/12.806175
Show Author Affiliations
Gerald J. Wilmink, Air Force Research Lab. (United States)
National Academy of Sciences (United States)
Benjamin D Rivest, Air Force Research Lab. (United States)
Bennett L. Ibey, Air Force Research Lab. (United States)
Luisiana X. Cundin, Conceptual Mindworks, Inc. (United States)
Eric C Haywood, Air Force Research Lab. (United States)
William P. Roach, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 7175:
Optical Interactions with Tissue and Cells XX
Steven L. Jacques; E. Duco Jansen; William P. Roach, Editor(s)

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