Manufacturers of optic components are faced by an growing demand for products which suffice both flat as well as spherical optical surfaces with increasing diameter in best quality. A possible use case for these surfaces are telescopes. This market trend introduces new challenges for the state-of-the-art measuring techniques, which are used to ensure the quality and dimensional stability of such surfaces. For standard mirror diameters of up to a few centimeters, corresponding measuring techniques are available, although still rather expensive. For the increasing demand of components with bigger diameters, the market does not yet provide appropriate solutions which guarantee the required exactness.
The EU-project OPTASENS was initiated to develop of a measuring technique which allows quality assurance for reflecting optical surfaces with a diameter of up to 800 millimeters with an accuracy of 40 nanometers. The project was realized in a two-year time frame and was carried out by University of Budapest, Technical University München, Micro-Epsilon Messtechnik GmbH & Co. KG, Ortenburg and Technische Hochschule Deggendorf.
|Participation of FORWISS|
The tasks of FORWISS included stabilizing data acquisition methods through a sensitivity analysis and developing a mathematical analysis and modeling of the whole measurement process. The institute defined a structure for the gradual precise measurement and developed numerical algorithms for nonlinear optimization of the single precision steps. Furthermore, FORWISS created an algorithm for accurate local surface measurements, developed a reconstruction algorithm (stitching) for the entire surface and tested and optimized the cycles for the algorithm as well as the entire measurement system.
Further Information can be found in the technical report titled "Mathematische Methoden zum Zusammensetzen einzeln erfasster dreidimensionaler Punktwolken für eine hoch genaue Vermessung großer optischer Oberflächen" (German only) at the webpage of the Department for Informatics and Mathematics at the Universität Passau.