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Journal of Biomedical Optics • Open Access

Light scattering of semitransparent sintered polytetrafluoroethylene films
Author(s): Qinghe Li; Bong-Jae Lee; Zhuomin M. Zhang; David W. Allen

Paper Abstract

Polytetrafluoroethylene (PTFE) is a strongly scattering material and has been regarded to have optical properties similar to biological tissues. In the present study, the bidirectional reflectance distribution function (BRDF) and the bidirectional transmittance distribution function (BTDF) of several PTFE films, with thicknesses from 0.11 to 10 mm, are measured using a laser scatterometer at the wavelength of 635 nm. The directional-hemispherical reflectance (R) and transmittance (T) were obtained by integrating BRDF and BTDF for normal incidence. Comparison of the ratio of the measured R and T with that calculated from the adding-doubling method allows the determination of the reduced scattering coefficient. Furthermore, the effect of surface scattering is investigated by measuring the polarization-dependent BRDF and BTDF at oblique incidence. By analyzing the measurement uncertainty of BTDF in the near-normal observation angles at normal incidence, the present authors found that the scattering coefficient of PTFE should exceed 1200 cm−1, which is much greater than that of biological tissues. On the other hand, the absorption coefficient of PTFE must be less than 0.01 cm−1, much smaller than that of biological tissues, a necessary condition to achieve R0.98 with a 10-mm-thick slab.

Paper Details

Date Published: 1 September 2008
PDF: 12 pages
J. Biomed. Opt. 13(5) 054064 doi: 10.1117/1.2992485
Published in: Journal of Biomedical Optics Volume 13, Issue 5
Show Author Affiliations
Qinghe Li, Georgia Institute of Technology (United States)
Bong-Jae Lee, Pittsburg State Univ. (United States)
Zhuomin M. Zhang, Georgia Institute of Technology (United States)
David W. Allen, National Institute of Standards and Technology (United States)

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