On the metrology of MSF errors after grinding

Nowadays the strict quality criteria for modern optical products lead to the use of the point contact processes for grinding and polishing. This art of manufacturing is especially sensitive to the occurring of the mid spatial frequency structures, which influence negative the optical properties of the lenses. Mid spatial frequency errors are too small to be eliminated as a form error, and too big to be polished away. The manufacturing chain consists of numerous steps. Finally, different mid spatial frequency errors commingle together and it is a difficult task to assign them to the proper process step. In the article we discuss the possibilities to analyze surfaces direct after grinding.