The actual surface state of optics surfaces

The surfaces of precision optics components made of glass such as lenses or prisms are commonly supposed to be of high purity and cleanliness. However, several effects and mechanisms may lead to contamination and modification of glass surfaces produced by conventional manufacturing, i.e., cutting, grinding, lapping, and polishing. Apart from mechanical impact such as compression and the generation of micro cracks and subsurface damages, a change in chemical composition may occur. This includes the dissolving and removal of essential components from the glass matrix via leaching or the adhesion and implantation of foreign matter originating from the used tools and applied operation materials and media via diffusion. Finally, the growth of hydrated silica might contribute to near-surface contamination by accumulating embedded impurities. In this contribution, such mechanisms are introduced. Moreover, the potentially resulting change in surface composition measured via spectroscopic techniques as well as its impact on optical properties and performance of precision optics components is discussed.