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Proceedings Paper

Characterization of wavefront variations in coated optics
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Paper Abstract

The wavefronts reflected by and transmitted through a coated substrate will be influenced by the non-uniformities of the coatings and distortion of the substrate produced as a result of coating stress. In this paper we describe the characterization procedure and results of a coated substrate for the Laser Interferometer Gravitational wave Observatory (LIGO) project. The fused silica substrate is 250 mm in diameter, 40 mm thick and on one side a multilayer anti- reflection coating is deposited and a 50% reflectivity multilayer coating on the other. To characterize the coatings, reflected and transmitted wavefront measurements were carried out with a 300 mm aperture phase-shifting Fizeau interferometer in combination with ellipsometric measurements of the coated surfaces. The interferometric measurements allowed the deformation of the substrate by the coatings to be assessed while the ellipsometric measurements allowed the coatings' thickness variation to be measured and the resulting phase variation in the reflected and transmitted wavefronts to be estimated. The measurements revealed substrate deformation of about 45 nm with a coating relief non-uniformity of about 5 nm over a working aperture of 200 mm.

Paper Details

Date Published: 11 November 1999
PDF: 12 pages
Proc. SPIE 3782, Optical Manufacturing and Testing III, (11 November 1999); doi: 10.1117/12.369189
Show Author Affiliations
Bozenko F. Oreb, CSIRO (Australia)
Roger Pryce Netterfield, CSIRO (Australia)
Christopher J. Walsh, CSIRO (Australia)
Christopher H. Freund, CSIRO (Australia)
Achim J. Leistner, CSIRO (Australia)
Jeffrey A. Seckold, CSIRO (Australia)

Published in SPIE Proceedings Vol. 3782:
Optical Manufacturing and Testing III
H. Philip Stahl, Editor(s)

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