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Proceedings Paper

Primary mirror segmentation studies for the Thirty Meter Telescope
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Paper Abstract

The Thirty Meter Telescope (TMT) project, a partnership between ACURA, Caltech, and the University of California, is currently developing a 30-meter diameter optical telescope. The primary mirror will be composed of 492 low expansion glass segments. Each segment is hexagonal, nominally measuring 1.44m across the corners. Because the TMT primary mirror is curved (i.e. not flat) and segmented with uniform 2.5mm nominal gaps, the resulting hexagonal segment outlines cannot all be identical. All segmentation approaches studied result in some combination of shape and size variations. These variations range from fractions of a millimeter to several millimeters. Segmentation schemes for the TMT primary mirror are described in some detail. Various segmentation approaches are considered, with the goal being to minimize various measures of shape variation between segments, thereby reducing overall design complexity and cost. Two radial scaling formulations are evaluated for their effectiveness at achieving these goals. Optimal tuning of these formulations and detailed statistics of the resulting segment shapes are provided. Finally, we present the rationale used for selecting the preferred segmentation approach for TMT.

Paper Details

Date Published: 23 July 2008
PDF: 15 pages
Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 70180S (23 July 2008); doi: 10.1117/12.790206
Show Author Affiliations
Curtis Baffes, Jet Propulsion Lab. (United States)
Terry Mast, Univ. of California, Santa Cruz (United States)
Jerry Nelson, Univ. of California, Santa Cruz (United States)
Eric Ponslet, HYTEC, Inc. (United States)
Vince Stephens, HYTEC, Inc. (United States)
Larry Stepp, TMT Observatory Corp. (United States)
Eric C. Williams, TMT Observatory Corp. (United States)

Published in SPIE Proceedings Vol. 7018:
Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation
Eli Atad-Ettedgui; Dietrich Lemke, Editor(s)

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