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Proceedings Paper

Calculation of the reference surface error by analyzing a multiple set of sub-measurements
Author(s): Roland Maurer; Florian Schneider; Christine Wünsche; Rolf Rascher
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Paper Abstract

In the field of precision optics the interferometry is the most applied measurement method to test spherical and flat objects. In principle, a standard interferometer setup is limited to these surface geometries, but interferometric systems may be modified with the aid of CGH’s or the stitching technology. As a consequence aspherical shapes and even freeform optics are measurable up to a certain extent. In an interferometric measurement the measured variable is the optical path difference (OPD) between the reference wave and the test wave. Based on the detected OPD the surface error of the test object is calculated by phase shifting methods for instance. It is evident, that the error from the reference surface affects the determination of the test object surface error. One option to face this problem is the calibration of the system prior to the measurement. For this the determination of the reference surface error may be realized with the aid of a two sphere test or a random ball test e.g. [1]. In the well-known SSI-technology from QED technologies the reference surface error is calculated on the basis of the sub-measurements. Due to the self-calibrating nature of the QED stitching principle [2-4] a calibration of the system prior to the measurement is not necessary. The University of Applied Sciences Deggendorf has implemented a similar algorithm to estimate the reference wave front error, or to be exact the error of the whole optical system, based on a multiple set of sub-measurements. This paper describes the applied algorithm in detail and discusses the results. To verify the implemented tool the results are compared to the outcomes of the QED stitching software.

Paper Details

Date Published: 7 September 2013
PDF: 12 pages
Proc. SPIE 8838, Optical Manufacturing and Testing X, 88380E (7 September 2013); doi: 10.1117/12.2024003
Show Author Affiliations
Roland Maurer, Univ. of Applied Sciences Deggendorf (Germany)
Florian Schneider, Univ. of Applied Sciences Deggendorf (Germany)
Christine Wünsche, Univ. of Applied Sciences Deggendorf (Germany)
Rolf Rascher, Univ. of Applied Sciences Deggendorf (Germany)

Published in SPIE Proceedings Vol. 8838:
Optical Manufacturing and Testing X
Oliver W. Fähnle; Ray Williamson; Dae Wook Kim, Editor(s)

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