Statistical Properties of Surfaces: Features of the Calculation of the Autocovariance Function from the Scattering Indicatrix

摘要

Features of the calculation of the autocovariance function (ACF) of an isotropic surface from experiments on measuring the angular dependence of scattered light are analyzed. The analytical extrapolation of the experimentally obtained function of power spectral density (PSD) of the surface relief based on the application of an adequate model for its description is shown to improve the accuracy of calculations of ACF. In this case, the mean-square roughness of the surface microrelief δ_(TIS)~2 determined from the data of total integrated scattering (TIS) allows the quantitative normalization of the ACF to be carried out. In the studies of the structure of a complicated surface (a superposition of isotropic and periodic components), the inclusion of PSD features allows one to carry out adequate statistical analysis by using techniques for calculating the ACF of homogeneous isotropic surfaces. The answer to this question is in the detailed study of experimentally obtained dependences of PSD and identification of their domains corresponding to isotropic scatterers, periodic structures, or characteristic dimensions at the surface. The validity of the proposed approach is confirmed by independent studies with the use of atomic force microscopy (AFM).