Influence of boundary reflection and refraction on diffusive photon transport.

We report computer simulations which test the accuracy of the diffusion theories used in the analysis of multiple light scattering data. Explicitly including scattering anisotropy and boundary reflections, we find that the predicted probability for transmission through a slab is accurate to 1% if the slab thickness is greater than about 5 transport mean free paths. For strictly isotropic scattering and no boundary reflections, the exact diffusion theory prediction is accurate to this level for all thicknesses. In addition, we predict how the angular distribution of transmitted photons is affected by boundary reflectivity, both with and without refraction. Simulations show that, to a similar extent, corrections to diffusion theory from a more general transport theory are not needed here, either. Our results suggest an experimental means of measuring the so-called extrapolation length ratio which characterizes boundary effects, and thus have important implications for the analysis of static transmission and diffusing-wave spectroscopy data. Disciplines Physical Sciences and Mathematics | Physics Comments At the time of publication, author Douglas J. Durian was affiliated with University of California, Los Angeles. Currently, he is a faculty member at the Physics Department at the University of Pennsylvania. This journal article is available at ScholarlyCommons: https://repository.upenn.edu/physics_papers/631 PHYSICAL REVIEW E VOLUME 50, NUMBER 2 AUGUST 1994 Influence of boundary reflection and refraction on diffusive photon transport