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Proceedings Paper

Interferometric and deflectometric flatness metrology with nanometre measurement uncertainties for optics up to 1 metre at PTB
Author(s): G. Ehret; H. Reinsch; M. Schulz
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Paper Abstract

High-precision topography measurements of nearly flat specimens with nanometre uncertainty are still demanding. They are needed for synchrotron or other high-quality optical mirrors. At the Physikalisch-Technische Bundesanstalt (PTB), we operate an interferometric setup and a small-angle deflectometric setup for flatness measurement. We present both systems, show the measurement uncertainties and discuss the pros and cons of interferometric and gradient based measurement systems. To achieve the nanometre level in flatness metrology, the environmental conditions and the holder of the specimen are very important. We show measurements of topography changes due to delayed elasticity effects. We demonstrate current developments with the small-angle deflectometer, especially to improve the lateral resolution.

Paper Details

Date Published: 18 November 2019
PDF: 10 pages
Proc. SPIE 11189, Optical Metrology and Inspection for Industrial Applications VI, 1118905 (18 November 2019); doi: 10.1117/12.2538872
Show Author Affiliations
G. Ehret, Physikalisch-Technische Bundesanstalt (Germany)
H. Reinsch, Physikalisch-Technische Bundesanstalt (Germany)
M. Schulz, Physikalisch-Technische Bundesanstalt (Germany)

Published in SPIE Proceedings Vol. 11189:
Optical Metrology and Inspection for Industrial Applications VI
Sen Han; Toru Yoshizawa; Song Zhang; Benyong Chen, Editor(s)

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