Nanoroughness characterization of complex surfaces by advanced light scattering techniques

The technological development places ever increasing demands on high-precision optical and non-optical surfaces. New manufacturing techniques are being developed to generate smooth surfaces even on large and curved surfaces. Yet there is an urgent need for measurement tools which allow a rapid and sensitive inspection of the quality and homogeneity of surface finish even on complex surfaces. Light scattering measurements are best suited to meet these requirements. Recently developed instruments for total and angle resolved light scattering measurements at various wavelengths are presented. Moreover, it is demonstrated how nanoroughness and roughness spectra are retrieved from measurement results. Examples of application are discussed for diamond-turned and polished surfaces as well as for multilayer coated surfaces with roughness levels ranging from below 1 to several nanometers rms. In addition to the laboratory-based instruments, we present new compact and table-top systems which we currently develop for scatter-based roughness measurements close to optical manufacturing processes.