Diffusion of Polarized Light

Abstract

We study partially polarized light propagation in random media governed by the theory of radiative transport. In particular, we derive a diffusion approximation when scattering is strong and absorption is weak. This diffusion approximation is substantially easier to solve than the vector radiative transport equation because it requires only the solution of a scalar problem. Included in this analysis is the derivation of a boundary layer solution that corrects the diffusion approximation near the boundaries and provides the means to derive boundary conditions for the diffusion approximation. We give an explicit solution for this boundary layer solution in terms of plane wave solutions that we calculate numerically using the discrete ordinate method. We evaluate the effectiveness of this diffusion approximation through comparison with the numerical solution of the full problem.