Depolarization of light in a multiply scattering medium: effect of the refractive index of a scatterer.

We report the results of a study carried out to investigate the influence of the refractive index and size parameter of a scatterer on the depolarization of linearly and circularly polarized light in a turbid medium. The results show that for a given refractive index of the surrounding medium, the influence of the refractive index of the scatterer on the depolarization of both linearly and circularly polarized light is rather weak for samples with smaller-sized scatterers (Rayleigh scatterers, radius a<<lambda , anisotropy parameter g < or =0.2 ). For a given value of optical thickness (tau= mu(s) xd , mu(s) being the scattering coefficient, d the physical thickness), the depolarization of circularly polarized light was observed to be higher than that of linearly polarized light for these samples. In contrast, for samples prepared using larger-sized scatterers (Mie scatterers, a > or =lambda , g > or =0.7), linearly polarized light was observed to depolarize much faster than circularly polarized light when the refractive index of scatterers was large (n=1.59) but no appreciable difference in depolarization of linearly and circularly polarized light was observed when the refractive index of scatterers had a lower value (n=1.37) . Further, for scattering samples having Mie scatterers, for comparable values of tau and g , depolarization of polarized light was much higher for samples with scatterers of lower refractive index.