Depolarization of light in tissue phantoms - effect of collection geometry

We report measurement of depolarization of light on propagation through matched scattering samples having the same anisotropy parameter (g) and optical thickness (tau = mu(s) x d, d being the physical thickness) but different values for scattering coefficient (mu(s)). Significant differences were observed in the depolarization behavior of the samples so matched. The depolarization of both linear and circularly polarized light was always larger for the sample with higher value of mu(s). Further, for lower value of g (g similar to 0.1), the difference in depolarization between matched samples was larger for circularly polarized light than that for linearly polarized light. Exactly the opposite result was obtained for matched samples with larger g values (g similar to 0.9). We show that these differences in the depolarization behavior of matched samples are dependent on the collection geometry and arise because for a given collection angle, a greater fraction of multiply scattered photons are collected for the sample having higher mu(s). (C) 2003 Elsevier Science B.V. All rights reserved.