Primary mirror segmentation studies for the Thirty Meter Telescope

Curtis Baffes; Terry Mast; Jerry Nelson; Eric Ponslet; Vince Stephens; Larry Stepp; Eric C. Williams

doi:10.1117/12.790206

23 July 2008 Primary mirror segmentation studies for the Thirty Meter Telescope

Curtis Baffes, Terry Mast, Jerry Nelson, Eric Ponslet, Vince Stephens, Larry Stepp, Eric C. Williams

Proceedings Volume 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation; 70180S (2008) https://doi.org/10.1117/12.790206
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

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.

Citation Download Citation

Curtis Baffes, Terry Mast, Jerry Nelson, Eric Ponslet, Vince Stephens, Larry Stepp, and Eric C. Williams "Primary mirror segmentation studies for the Thirty Meter Telescope", Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 70180S (23 July 2008); https://doi.org/10.1117/12.790206

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