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Proceedings Paper

Plasma surface figuring of large optical components
Author(s): R. Jourdain; M. Castelli; P. Morantz; P. Shore
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Paper Abstract

Fast figuring of large optical components is well known as a highly challenging manufacturing issue. Different manufacturing technologies including: magnetorheological finishing, loose abrasive polishing, ion beam figuring are presently employed. Yet, these technologies are slow and lead to expensive optics. This explains why plasma-based processes operating at atmospheric pressure have been researched as a cost effective means for figure correction of metre scale optical surfaces. In this paper, fast figure correction of a large optical surface is reported using the Reactive Atom Plasma (RAP) process. Achievements are shown following the scaling-up of the RAP figuring process to a 400 mm diameter area of a substrate made of Corning ULE®. The pre-processing spherical surface is characterized by a 3 metres radius of curvature, 2.3 μm PVr (373nm RMS), and 1.2 nm Sq nanometre roughness. The nanometre scale correction figuring system used for this research work is named the HELIOS 1200, and it is equipped with a unique plasma torch which is driven by a dedicated tool path algorithm. Topography map measurements were carried out using a vertical work station instrumented by a Zygo DynaFiz interferometer. Figuring results, together with the processing times, convergence levels and number of iterations, are reported. The results illustrate the significant potential and advantage of plasma processing for figuring correction of large silicon based optical components.

Paper Details

Date Published: 4 May 2012
PDF: 6 pages
Proc. SPIE 8430, Optical Micro- and Nanometrology IV, 843011 (4 May 2012); doi: 10.1117/12.924798
Show Author Affiliations
R. Jourdain, Cranfield Univ. (United Kingdom)
M. Castelli, Cranfield Univ. (United Kingdom)
P. Morantz, Cranfield Univ. (United Kingdom)
P. Shore, Cranfield Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 8430:
Optical Micro- and Nanometrology IV
Christophe Gorecki; Anand K. Asundi; Wolfgang Osten, Editor(s)

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