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Proceedings Paper

Form measurement of large optics with deflectometric and interferometric procedures at PTB
Author(s): Gerd Ehret; Sören Laubach; Andreas Straub; Michael Schulz
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Paper Abstract

There is an increasing demand for accurate form measurements of large optics with dimensions of up to one meter. For example, reference flats of Fizeau interferometers have to be known in the nanometer range. Synchrotrons or XFEL mirrors are often more curved, but nevertheless have to be manufactured and measured at a comparable or even better level of accuracy. Different approaches like deflectometry or interferometry in combination with stitching methods are typically used for these purposes, but obtaining the low uncertainty levels needed is still a considerable challenge. In this paper, measuring concepts and systems used at PTB for these purposes will be presented. For flatness measurements, a so-called Deflectometric Flatness Reference (DFR) system and a Fizeau interferometer were used. Slightly curved surfaces can be measured with the Traceable Multi Sensor (TMS) method, and CMMs with point or line sensors were also available. We will also present the current measurement capabilities and some measurement examples of form measurements of optical surfaces at PTB. The different setups and their pros and cons will be discussed. Future developments in the field of large-optics measurement will also be shown.

Paper Details

Date Published: 30 June 2016
PDF: 4 pages
Proc. SPIE 10009, Third European Seminar on Precision Optics Manufacturing, 100090B (30 June 2016); doi: 10.1117/12.2235474
Show Author Affiliations
Gerd Ehret, Physikalisch-Technische Bundesanstalt (Germany)
Sören Laubach, Physikalisch-Technische Bundesanstalt (Germany)
Andreas Straub, Physikalisch-Technische Bundesanstalt (Germany)
Michael Schulz, Physikalisch-Technische Bundesanstalt (Germany)

Published in SPIE Proceedings Vol. 10009:
Third European Seminar on Precision Optics Manufacturing
Rolf Rascher; Oliver Fähnle; Christine Wünsche; Christian Schopf, Editor(s)

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