Scattering of laser and x-ray radiation by ultrasmooth surfaces formed by diamond turning. Experimental results

An original method was developed for investigating the quality of the surfaces of laser mirrors formed by diamond turning. This method was based on the scattering of laser and x-ray radiation from the mirrors. An analysis of the experimental scattering diagrams made it possible to identify not only the main harmonic component of the microrelief, but also a series of additional long-wavelength harmonics which were not multiples of the main one. A study was made of the influence of the curvature of the surface relief on the shape of the scattering diagram. Criteria were formulated for the relief curvature, which would make it possible to analyze quantitatively the scattering data. The reliability of the results was confirmed by the agreement of the surface data obtained from the laser and x-ray (with wavelengths in the ratio ~ 4000) scattering diagram obtained for different angles of incidence. The proposed method should find applications in quality control of various optical components irrespective of the material of the reflecting or transmitting coating.