Polarization scattering from rough surfaces based on the vector Kirchhoff diffraction model

Current simulations of optical polarization scattering and emission for remote sensing applications employ geometric optics. The approach is mathematically simple but lacks soundness of physics as it relies upon artificial adjustment of polarized specular and unpolarized diffuse components in the scattered radiation to match experiments. In order to improve the current polarization scattering model, we are developing, a model based on the vector Kirchhoff diffraction integral. The vector Kirchhoff diffraction model will simulate a main lobe and a diffraction pattern for each rough surface facet of a material. Predictioins of measurable polarization states will result through calculating the diffraction lobes of different facet orientations. The Kirchhoff approach will produce specular and diffuse components solely depending on surface characteristics including index of refraction and incident/scattering angles. Our mathematical model is an extension of Beckmann's scalar rough surface scattering model. The roughness of the surface is treated statistically using the rms roughness height and the autocorrelation length and a Gaussian distribution is used for the roughness slope and facet normal. The shadowing by neighboring rough surface facets is also taken into account in the model. The results of the model are to be compared with published results of polarization scattering experiment.