Bidirectional Scattering of Electromagnetic Waves from the Volume of Dielectric Materials

Abstract

A series of optical‐scattering experiments was performed on dielectric materials of various pigmentation and surface roughnesses. Cross‐section data obtained by these experiments were then analyzed to ascertain the angular, spectral, and polarization behavior of radiation scattered from the volume of the samples. The division of the scattered intensity into a surface and volume component was accomplished by deduction from previous knowledge of the surface‐scattering behavior and analysis of the cross‐polarized cross‐section variation with scattering angle. It was found that a consistent accurate description of observed scattering in the plane of incidence for all polarization combinations could be obtained by assuming a volume‐scattered component added incoherently with a surface‐scattered term which has already been described. The volume‐scattered term was found to be independent of surface roughness. Theoretical fits to the depolarized cross‐section data were also made with a model assuming scattering from media with random fluctuations of the refractive index. Although excellent agreement was obtained between the theoretical and observed angular behavior, the identification of such a random fluctuation process as being responsible for observed depolarization must be considered tentative.