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Proceedings Paper

Comparison of small angle deflectometric measurements with different apertures down to the sub-millimetre range
Author(s): Gerd Ehret; Susanne Quabis; Michael Schulz
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Paper Abstract

The Physikalisch-Technische Bundesanstalt (PTB) has developed and set up a deflectometer with sub-millimetre lateral resolution. This device uses an enhanced deflectometric method called ‘Exact Autocollimation Deflectometric Scanning’ (EADS), which makes use of two angle sensors. One angle sensor has a small beam aperture and scans the specimen by using a pentaprism or a double mirror unit. It operates as a null angle sensor and controls the tilting of the specimen by means of a piezo actuator, so that the reflected beam of the specimen always propagates back in the same direction. The null-angle sensor allows sub-millimetre apertures with sensitivities of better than 0.01 arcsec to be achieved. The tilt of the specimen is measured with the second angle sensor – usually a commercially available autocollimator – with a large aperture at a fixed distance. The surface topography is obtained by the numerical integration of the measured tilt angles. The measurement uncertainty associated with the resulting topography typically scales with the scan length. Here, we present measurements with different lateral resolutions down to 0.3 mm.

Paper Details

Date Published: 25 October 2016
PDF: 8 pages
Proc. SPIE 9687, 8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Subnanometer Accuracy Measurement for Synchrotron Optics and X-Ray Optics, 968702 (25 October 2016); doi: 10.1117/12.2243608
Show Author Affiliations
Gerd Ehret, Physikalisch-Technische Bundesanstalt (Germany)
Susanne Quabis, Physikalisch-Technische Bundesanstalt (Germany)
Michael Schulz, Physikalisch-Technische Bundesanstalt (Germany)


Published in SPIE Proceedings Vol. 9687:
8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Subnanometer Accuracy Measurement for Synchrotron Optics and X-Ray Optics
Shinan Qian; Mourad Idir; Daniele Cocco; Tiqiao Xiao; Kazuto Yamauchi, Editor(s)

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