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Proceedings Paper

Subaperture approaches for asphere polishing and metrology
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Paper Abstract

This paper summarizes some of QED Technologies’ latest developments in the field of high-precision polishing and metrology. Magneto-Rheological Finishing (MRF) is a deterministic sub-aperture polishing process that overcomes many of the fundamental limitations of traditional finishing. MRF has demonstrated the ability to produce optical surfaces with accuracies better than 30 nm peak-to-valley (PV) and surface micro-roughness less than 0.5 nm rms on a wide variety of optical glasses, single crystals, and glass-ceramics. The MR fluid forms a polishing tool that is perfectly conformal and therefore can polish a variety of shapes, including flats, spheres, aspheres, prisms, and cylinders, with either round or rectangular apertures. QED’s Sub-aperture Stitching Interferometer (SSI) complements MRF by extending the effective aperture, accuracy, resolution, and dynamic range of a phase-shifting interferometer. This workstation performs automated sub-aperture stitching measurements of spheres, flats, and mild aspheres. It combines a six-axis precision stage system, a commercial Fizeau interferometer, and specially developed software that automates measurement design, data acquisition, and the reconstruction of the full-aperture map of figure error. Aside from the correction of sub-aperture placement errors (such as tilts, optical power, and registration effects), our software also accounts for reference-wave error, distortion, and other aberrations in the interferometer’s imaging optics. By addressing these matters up front, we avoid limitations encountered in earlier stitching work and significantly boost reproducibility beyond that of the integrated interferometer on its own.

Paper Details

Date Published: 10 February 2005
PDF: 16 pages
Proc. SPIE 5638, Optical Design and Testing II, (10 February 2005); doi: 10.1117/12.577539
Show Author Affiliations
Marc Tricard, QED Technologies, Inc. (United States)
Paul Dumas, QED Technologies, Inc. (United States)
Greg Forbes, QED Technologies, Inc. (United States)

Published in SPIE Proceedings Vol. 5638:
Optical Design and Testing II
Yongtian Wang; Zhicheng Weng; Shenghua Ye; Jose M. Sasian, Editor(s)

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