Production of 8.4 m primary mirror segments for GMT

H. M. Martin; R. Ceragioli; V. Gasho; B. T. Jannuzi; D. W. Kim; J. S. Kingsley; K. Law; A. Loeff; R. D. Lutz; S. Meyen; C. J. Oh; M. T. Tuell; S. N. Weinberger; S. C. West; R. Whitsitt; R. Wortley

doi:10.1117/12.2630378

20 September 2022 Production of 8.4 m primary mirror segments for GMT

H. M. Martin, R. Ceragioli, V. Gasho, B. T. Jannuzi, D. W. Kim, J. S. Kingsley, K. Law, A. Loeff, R. D. Lutz, S. Meyen, C. J. Oh, M. T. Tuell, S. N. Weinberger, S. C. West, R. Whitsitt, R. Wortley

Author Affiliations +

Proceedings Volume 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V; 121880J (2022) https://doi.org/10.1117/12.2630378
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Abstract

The Richard F. Caris Mirror Lab at the University of Arizona continues production of 8.4 m lightweight honeycomb segments for the primary mirror of the Giant Magellan Telescope. GMT’s 25 m primary mirror consists of a center segment surrounded by six off-axis segments, with an additional off-axis segment to allow continuous operation as segments are removed for coating. We cast the sixth segment (5 off-axis segments + center segment) in March 2021. As of June 2022 we have tentatively completed polishing of the third off-axis segment, and we are in the process of grinding the optical surface of off-axis Segment 5. For Segment 3, we improved the measurement accuracy for small-scale structure near the edge of the mirror, which has been a challenge for the off-axis segments. In addition to full-aperture interferometry and deflectometry, we used a 20 cm test plate to obtain high-resolution interferometric measurements of the edge.

Conference Presentation

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H. M. Martin, R. Ceragioli, V. Gasho, B. T. Jannuzi, D. W. Kim, J. S. Kingsley, K. Law, A. Loeff, R. D. Lutz, S. Meyen, C. J. Oh, M. T. Tuell, S. N. Weinberger, S. C. West, R. Whitsitt, and R. Wortley "Production of 8.4 m primary mirror segments for GMT", Proc. SPIE 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V, 121880J (20 September 2022); https://doi.org/10.1117/12.2630378

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