M. Motamedi, W. F. Cheong, G. Yoong, A. J. Welch

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Recent measurements of the phase function of biological tissue such as blood and skin for visible and near-IR wavelengths indicate a highly anisotropic scattering behavior. This suggests that the photon diffusion approximation is not valid for thin layers of an anistropic medium or in the near-surface regions of optically thick tissues. Instead, a combination of small-angle scattering approximation to account for the anisotropic component of the phase function and the diffusion approximation has been used to study the off-axis propagation in biological tissues with a high degree of anisotropy. The former computes the near-axis radiance, and the latter estimates the off-axis light spatial distribution using the on-axis radiance as an external source. The results of the computation of total light intensity as a function of axial as well as radial distance for a 2-mm spot size show the existence of two regions. In the first region, proximal to the surface, scattering is confined to a narrow forward angle. This is followed by a second region of more diffuse scattering. These results indicate that for highly anisotropic scattering the combined model gives a better estimation of the spatial light distribution than each model independently.

Original languageEnglish (US)
Title of host publicationUnknown Host Publication Title
PublisherOptical Soc of America
Number of pages3
ISBN (Print)0936659491
StatePublished - 1987
Externally publishedYes

ASJC Scopus subject areas

  • General Engineering


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