Roughness and defect characterization of optical surfaces by light scattering measurements

The microtopography of a certain surface is a complicated structure varying across the complete surface. Every surface has different elements of microstructure. In this paper, we consider roughness as a dine structure and defects as large structure elements. Roughnessmeasurement on BK7-glass and CaF2 samples is considered using different techniques. The comparsion includes the automatic scatterometer STREUIX2 and a TIS-measurement system, the ZYGO microprofilometer MAXIM 3D, and the NANO SCOPE III of Digital Instruments. For the investigation of scattering characteristics of different surface defects, a special measuring device was developed. The scattered light distribution of different defects and contaminations measured with this set-up is discussed.