Comparisons of theory and experiment in light scattering from a randomly rough surface

Abstract

For a conducting surface with one-dimensional roughness, we compare experimental and theoretical results for the four unique elements of the Stokes-scattering matrix that provide a complete description of the diffusely scattered light. The rough surface has been fabricated with new techniques and is strictly one dimensional, and scattered intensities at infrared wavelengths show clear backscattering enhancement that arises from multiple scattering within surface corrugations. To obtain theoretical results for the Stokes matrix elements, we numerically apply an impedance boundary-condition method, appropriate for the roughness and the high conductivity of the experimental surface, to a statistical ensemble of rough surfaces. The experimental surface has been found to have nearly Gaussian first-order height statistics, and experimental measurements of the matrix elements are compared with theoretical results for a surface consistent with a Gaussian process. These comparisons suggest that there is more multiple scattering in the experimental data than is accounted for by the theoretical calculations. We attribute this observation to the properties of the second derivative of the experimental surface, which are found to be inconsistent with those of a Gaussian process. In further calculations that take account of the unusual properties of the experimental surface, excellent agreement of theoretical and experimental results is obtained.