Roughness analysis of optical surfaces by x-ray scattering

A grazing incidence x-ray scattering (XRS) method, Order perturbation theory (FOPT), is stated briefly and an experimental facility based on an improved X-ray diffraction has been introduced, which can work with high performance. The x-ray scattering distributions of two super smooth silicon samples measured at the incidence angle 0.2 degree, as the x-ray wavelength is 0.154 nm, have been given and analyzed by the FOPT to give information about the surface profiles. As a comparison, the root mean square (RMS) surface roughness, grey-scale maps and one-dimensional power spectral density (1D PSD) have been derived from the atomic-force microscope (AFM) data. The results evaluated by FOPT are in good agreement with that of AFM, which indicates that x-ray scattering method is a practical characterization for the investigation of super smooth surfaces.