Determination of the spectral density function of the optical surface roughness

A method proposed for determining the statistical characteristics of roughness of optical surfaces, such as the spectral density function, rms deviation from the planarity, and correlation length, is based on measurements of the directional diagram of the radiation scattered by the substrate of a thin-film waveguide in the plane perpendicular to the plane of incidence. The proposed technique simplifies the analysis of the scattering pattern and appreciably increases the accuracy of determining the roughness characteristics, because the spectral density function coincides with the dependence of the scattered radiation intensity on the scattering angle. © 1999 MAHK "Hayka/Interperiodica".