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Optical Engineering

Metrological multispherical freeform artifact
Author(s): Gernot Blobel; Axel Wiegmann; Jens Siepmann; Michael Schulz
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Paper Abstract

Precisely known artifacts are required to characterize the accuracy of asphere and freeform measuring instruments. To this end the best knowledge of the surface characteristics in conjunction with a low measurement uncertainty are necessary. Because this is a challenging task for typical freeform surfaces used in optical systems, the concept of “metrological” artifacts is introduced. We have developed a multispherical freeform artifact for performance tests of tactile touch probe and contact-free optical measuring systems. The measurement accuracy of the complete form and the deviation from calibrated spherical sections can thus be determined. The radius calibration of multiple spherical sections is performed with an extended radius measuring procedure by interferometry. Evaluated surface forms of different measuring methods and the radii determined can be compared to each other. In this study, a multispherical freeform specimen made of copper, with two differing radii, has been measured by two optical measuring methods, a full field measuring tilted-wave interferometer and a high accuracy cylinder coordinate measuring machine with an optical probe. The surface form measurements are evaluated and compared, and the radii determined are compared to the results of a radius measurement bench.

Paper Details

Date Published: 16 March 2016
PDF: 8 pages
Opt. Eng. 55(7) 071202 doi: 10.1117/1.OE.55.7.071202
Published in: Optical Engineering Volume 55, Issue 7
Show Author Affiliations
Gernot Blobel, Physikalisch-Technische Bundesanstalt (Germany)
Axel Wiegmann, Physikalisch-Technische Bundesanstalt (Germany)
Mahr OKM GmbH (Germany)
Jens Siepmann, Mahr OKM GmbH (Germany)
Michael Schulz, Physikalisch-Technische Bundesanstalt (Germany)

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