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In the manufacturing process of aspheric glass lenses, the polishing step plays a key role with respect to the final quality of the lens as well as to the manufacturing costs. Due to the changing radius of curvature sub aperture tools are used for polishing aspherical lens elements. Even with small tools the changing radius has a significant influence to the wear function [1] [2]. This paper describes a method to calculate the removal based only on the surface shape and the material parameters of the tool.The described method can be used for any kind of surface, e.g. for freeform shapes.

During grinding step in manufacturing process of glass lenses it is important to control such parameters as shape and sub-surface damage (SSD) with high accuracy which essentially influences the duration and costs of the subsequent polishing process. Typically used methods suffer from limited resolution and are time consuming. That is why the nondestructive measurement of SSD is a challenge for the metrology of grinded surfaces. In order to detect these damages, the scanning short-coherence interferometer, a method very similar to optical coherence tomography, is setup and tested at Aalen University. The lens under test is mounted on a rotation stage which can be translated in lateral direction. The sensor beam of the interferometer is focused onto the sample and can be moved along the axial direction. Lateral positioning accuracy is 2 µm and lateral resolution is 4 µm. The system is able to measure SSD at several positions on a lens within 10 min inside the optical workshop.

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