Weak-localization effect for light backscattered by surfaces with a complex structure

Results of laboratory measurements of the weak-localization effect for ligh t scattered by surfaces with different characteristics are presented. The m easurements were made in a range of phase angles of 0.2 degrees-3.5 degrees . The aim of the measurements was to study the influence of the choice of s urface material (metal, dielectric), the size of particles of the scatterin g surface, their packing density, the reflectivity of a sample, and the wav elength of incident radiation on the effect. For the measurements, both non polarized and linearly polarized light was used. Powders of dielectric mate rials were found to enhance the weak-localization effect with increasing pa rticle size, but the effect weakened starting with a certain size of the or der of wavelength. The pressing of powders of dielectric transparent materi als enhanced the opposition effect. This was most pronounced for samples wi th small-sized particles. The phase dependence of brightness became wider a nd more linear with decreasing reflectivity of the surface. A qualitative d ifference in the behavior of the phase dependence for the ratio of cross- a nd copolarized components was observed. For metals and metal-like materials , the ratio increased with decreasing phase angle. Dielectrics were found t o have an opposite dependence. (C) 2000 MAIK "Nauka/Interperiodica".