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Proceedings Paper

Manufacture of large mirrors for ELTs: a fresh perspective
Author(s): Paul Shore; Philip Parr-Burman
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Paper Abstract

Large optical elements are pivotal to the success of proposed Extremely Large Telescopes (ELTs) and are expected to constitute a significant proportion of the overall cost. It is expected that primary mirrors will be formed from several hundred to a few thousand 1 - 2 metre hexagonal segments. Existing manufacturing methods developed for producing large precision optics are characterised by long process times, significant measurement iterations and a high dependency on human skill. A previous low demand level for large optics has resulted in a correspondingly low attention to their production optimisation. Established manufacturing techniques for large optics in high volumes limit the range of optical shapes to spherical and flat forms. Methods for producing mirrors to aspheric shapes have been developed and used for astronomical telescopes but the cost and timescales involved in making large numbers of aspheric elements with such technology could be prohibitive. To enable reliable and cost effective manufacturing of such mirrors in volume a fresh perspective is necessary. A review has been made of both existing state-of-the-art and developing technologies which could improve the manufacturing efficiency of large optics processing. The suggested way forward is a manufacturing chain based on closely integrated machining and metrology operations. Capability of this integrated manufacturing route is oriented around “free form” aspheric surfaces but optimised to be cost competitive with established processes applicable to only spherical and flat surfaces.

Paper Details

Date Published: 26 February 2004
PDF: 8 pages
Proc. SPIE 5252, Optical Fabrication, Testing, and Metrology, (26 February 2004); doi: 10.1117/12.514698
Show Author Affiliations
Paul Shore, Cranfield Univ. (United Kingdom)
Philip Parr-Burman, UK Astronomy Technology Ctr. (United Kingdom)

Published in SPIE Proceedings Vol. 5252:
Optical Fabrication, Testing, and Metrology
Roland Geyl; David Rimmer; Lingli Wang, Editor(s)

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