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Mathematical Modelling and Data Analysis

Department 8.4

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Title: Evaluation of absolute form measurements using a tilted-wave interferometer
Author(s): I. Fortmeier, M. Stavridis, A. Wiegmann, M. Schulz, W. Osten and C. Elster
Journal: Opt. Express
Year: 2016
Volume: 24
Issue: 4
Pages: 3393--3404
DOI: 10.1364/OE.24.003393
Web URL: http://www.opticsexpress.org/abstract.cfm?URI=oe-24-4-3393
Keywords: Interferometry; Metrology; Surface measurements, figure; Aspherics
Tags: 8.42,Form,EMRP-Form
Abstract: Tilted-wave interferometry is a promising measurement technique for the highly accurate measurement of aspheres and freeform surfaces. However, the interferometric fringe evaluation of the sub-apertures causes unknown patch offsets, which currently prevent this measurement technique from providing absolute measurements. Simple strategies, such as constructing differences of optical path length differences (OPDs) or ignoring the piston parameter, can diminish the accuracy resulting from the absolute form measurement. Additional information is needed instead; in this paper, the required accuracy of such information is explored in virtual experiments. Our simulation study reveals that, when one absolute OPD is known within a range of 500 nm, the accuracy of the final measurement result is significantly enhanced.

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