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Precision optical components are usually machined by grinding and polishing in several steps with increasing accuracy. Spherical surfaces will be finished in a last step with large tools to smooth the surface. The requested surface accuracy of non-spherical surfaces only can be achieved with tools in point contact to the surface. So called mid-frequency errors (MSFE) can accumulate with zonal processes. This work is on the formation of surface errors from grinding to polishing by conducting an analysis of the surfaces in their machining steps by non-contact interferometric methods. The errors on the surface can be distinguished as described in DIN 4760 whereby 2nd to 3rd order errors are the so-called MSFE. By appropriate filtering of the measured data frequencies of errors can be suppressed in a manner that only defined spatial frequencies will be shown in the surface plot. It can be observed that some frequencies already may be formed in the early machining steps like grinding and main-polishing. Additionally it is known that MSFE can be produced by the process itself and other side effects. Beside a description of surface errors based on the limits of measurement technologies, different formation mechanisms for selected spatial frequencies are presented. A correction may be only possible by tools that have a lateral size below the wavelength of the error structure. The presented considerations may be used to develop proposals to handle surface errors. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

Zeitschriftenartikel

Christine Wünsche, Heiko Biskup, Rolf Rascher, Sebastian Draxinger, Johannes Liebl

Process developement fort the reproducible roughness measurement of optical surfaces using white light interferometry

International Journal of Metrology and Quality Engineering (EDP Sciences), vol. 5, no. 1, pp. 29-35

2014

Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

Beitrag (Sammelband oder Tagungsband)

O. Fähnle, Christine Wünsche, Heiko Biskup, Rolf Rascher, E. Langenbach, F. Frost, A. Schindler, Johannes Liebl

Generation and field testing of roughness reference samples for industrial testing of surface roughness levels below 0.5nm Sq

Proceedings of EOSAM 2014 (European Optical Society Annual Meeting) [Sep 15-19 2014, Berlin, Germany]

2014

Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

Beitrag (Sammelband oder Tagungsband)

Christine Wünsche, Heiko Biskup, Roland Maurer, Rolf Rascher, Christian J. Trum

Determination of a suitable parameter field for the active fluid jet polishing process

Optifab 2013, vol. Volume 8884

2013

ISBN: 9780819497475

DOI: 10.1117/12.2028752

Abstract anzeigen

In 2012 a well-known company in the field of high precision optics assigned the University of Applied Sciences Deggendorf to determine a suitable parameter field for the active fluid jet polishing (AFJP) process in order to reach a surface accuracy of at least lambda / 5. The active fluid jet polishing is a relatively new and an affordable sub-aperture polishing process. For a fast and precise identification of the parameter field a considered design of experiment is necessary. The available control variables were the rotational speed of the nozzle, the distance between the test object and the jet, the feed rate, the material of the pin inside the nozzle and the material of the test object itself. In order to reach a significant data density on the one hand and to minimize the number of test runs on the other hand a meander shaped tool path was chosen. At each blank nine paths had been driven whereby at each path another parameter combination was picked. Thus with only one test object nine parameter settings may be evaluated. For the automatized analysis of the tracks a software tool was developed. The software evaluates ten sections which orthogonally intersect the nine tracks on the test-lens. The significant measurement parameters per section are the width and the height of each path as well as the surface roughness within the polished tracks. With the aid of these parameters and further statistical evaluations a suitable parameter field for the goal to find a constant and predictable removal spot was determined. Furthermore up to now over 60 test runs have been successfully finished with nine parameter combinations in each case. As a consequence a test evaluation by hand would be very time-consuming and the software facilitates it dramatically.

Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

Vortrag

Christine Wünsche, Heiko Biskup, Rolf Rascher

Poliermittelerprobung I

Spectaris - 4. Treffen des Industriekonsortiums Seltene Erden, Teisnach

Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

Vortrag

Christine Wünsche, Heiko Biskup, Rolf Rascher

Laserdiffraktometrie - Korngrößenverteilung in Poliermitteln

Posterbeitrag

5. Optikseminar, Teisnach

Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen