Primary mirror aluminizing operations at the Large Binocular Telescope

J. M. Hill; B. Atwood; M. L. Edwards; M. Gardiner; J. P. Haddad; J. Howard; D. P. Pappalardo; J. Riedl; B. A. Sabol; J.T. Williams

doi:10.1117/12.2563170

13 December 2020 Primary mirror aluminizing operations at the Large Binocular Telescope

J. M. Hill, B. Atwood, M. L. Edwards, M. Gardiner, J. P. Haddad, J. Howard, D. P. Pappalardo, J. Riedl, B. A. Sabol, J.T. Williams

Author Affiliations +

Proceedings Volume 11451, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV; 114511M (2020) https://doi.org/10.1117/12.2563170
Event: SPIE Astronomical Telescopes + Instrumentation, 2020, Online Only

Abstract

We summarize the operational realities of re-aluminizing 8.4-meter primary mirrors in-situ on the Large Binocular Telescope. We review the evaporative coating system design, and summarize its performance in the 16 coatings since 2005. A mostly manual system with long-handled mops and traditional chemicals is used to remove the old coating and to clean the glass surface. After cleaning, the telescope is moved to horizon-pointing orientation and the aluminizing belljar is mounted to the primary mirror cell using the overhead crane internal to the enclosure. We report on the multi-year struggle to understand variations in deposition rate among the 28 crucibles that evaporate the aluminum. We describe the challenges of making operational improvements to a system that must reliably coat one of the two primary mirrors every year, and we report on some lessons learned along the way.

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Citation Download Citation

J. M. Hill, B. Atwood, M. L. Edwards, M. Gardiner, J. P. Haddad, J. Howard, D. P. Pappalardo, J. Riedl, B. A. Sabol, and J.T. Williams "Primary mirror aluminizing operations at the Large Binocular Telescope", Proc. SPIE 11451, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV, 114511M (13 December 2020); https://doi.org/10.1117/12.2563170

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