Optical issues for giant telescopes with extremely fast primary mirrors

James H. Burge; Hubert M. Martin

doi:10.1117/12.459934

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30 January 2003 Optical issues for giant telescopes with extremely fast primary mirrors

James H. Burge, Hubert M. Martin

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Proceedings Volume 4840, Future Giant Telescopes; (2003) https://doi.org/10.1117/12.459934
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

Abstract

Existing design rules break down as we plan for a new generation of giant optical telescopes of 20, 30, 50, even 100 meters in diameter. One might expect these telescopes to converge on the design universally ac-cepted for similarly sized radio telescopes, with their highly aspheric, ~ f/0.4, primary dish. But most of the optical design concepts now under consideration have favored spherical or relatively slow paraboloidal surfaces, leading to a much larger telescope, more subject to wind buffeting, and requiring gargantuan en-closures for protection. This paper explores issues and limitations for building and operating telescopes as the primary focal ratio is reduced to a value as small as f/0.4. Such compactness will be particularly impor-tant for mechanical stability, cost control and for large telescopes that must move continuously on a track, as in the 20/20 concept. We find that fabrication and alignment methods for telescopes using numerous small (1-m class) segments are driven to long focal ratios, while those using few large, actively controlled segments can be made as fast as f/0.5.

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James H. Burge and Hubert M. Martin "Optical issues for giant telescopes with extremely fast primary mirrors", Proc. SPIE 4840, Future Giant Telescopes, (30 January 2003); https://doi.org/10.1117/12.459934

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