Fabrication of large secondary mirrors for astronomical telescopes

Bryan Keener Smith; James H. Burge; Hubert M. Martin

doi:10.1117/12.295151

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1 November 1997 Fabrication of large secondary mirrors for astronomical telescopes

Bryan Keener Smith, James H. Burge, Hubert M. Martin

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Proceedings Volume 3134, Optical Manufacturing and Testing II; (1997) https://doi.org/10.1117/12.295151
Event: Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United States

Abstract

A new class of telescope is being built with primary mirrors as large as 8.4 meters in diameter and as fast as f/1. Fabricating the secondary mirrors for these telescopes has presented tough challenges because of their large sizes, up to 1.7 meter diameter; their aspheric departure of more than 300 microns; the required figure accuracy of a few tens of nanometers; and the fact that they are typically convex and difficult to measure. We have developed tools and techniques to meet these demands to produce secondary mirrors efficiently and accurately. A dedicated facility was constructed in the mirror lab that integrates a 1.8-m stressed-lap polishing machine with interferometric and mechanical measuring systems. This paper presents data from a 1.15-m secondary that was finished in our shop, and from two other large mirrors that are currently being fabricated.

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Bryan Keener Smith, James H. Burge, and Hubert M. Martin "Fabrication of large secondary mirrors for astronomical telescopes", Proc. SPIE 3134, Optical Manufacturing and Testing II, (1 November 1997); https://doi.org/10.1117/12.295151

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