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Proceedings Paper

Final acceptance testing of the LSST monolithic primary/tertiary mirror
Author(s): Michael T. Tuell; James H. Burge; Brian Cuerden; William Gressler; Hubert M. Martin; Steven C. West; Chunyu Zhao
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Paper Abstract

The Large Synoptic Survey Telescope (LSST) is a three-mirror wide-field survey telescope with the primary and tertiary mirrors on one monolithic substrate1. This substrate is made of Ohara E6 borosilicate glass in a honeycomb sandwich, spin cast at the Steward Observatory Mirror Lab at The University of Arizona2. Each surface is aspheric, with the specification in terms of conic constant error, maximum active bending forces and finally a structure function specification on the residual errors3. There are high-order deformation terms, but with no tolerance, any error is considered as a surface error and is included in the structure function. The radii of curvature are very different, requiring two independent test stations, each with instantaneous phase-shifting interferometers with null correctors. The primary null corrector is a standard two-element Offner null lens. The tertiary null corrector is a phase-etched computer-generated hologram (CGH). This paper details the two optical systems and their tolerances, showing that the uncertainty in measuring the figure is a small fraction of the structure function specification. Additional metrology includes the radii of curvature, optical axis locations, and relative surface tilts. The methods for measuring these will also be described along with their tolerances.

Paper Details

Date Published: 7 August 2014
PDF: 17 pages
Proc. SPIE 9151, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation, 91510W (7 August 2014); doi: 10.1117/12.2057076
Show Author Affiliations
Michael T. Tuell, Steward Observatory, The Univ. of Arizona (United States)
James H. Burge, Steward Observatory, The Univ. of Arizona (United States)
College of Optical Sciences, The Univ. of Arizona (United States)
Brian Cuerden, Steward Observatory, The Univ. of Arizona (United States)
William Gressler, National Optical Astronomy Observatory (United States)
Hubert M. Martin, Steward Observatory, The Univ. of Arizona (United States)
Steven C. West, Steward Observatory, The Univ. of Arizona (United States)
Chunyu Zhao, College of Optical Sciences, The Univ. of Arizona (United States)


Published in SPIE Proceedings Vol. 9151:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation
Ramón Navarro; Colin R. Cunningham; Allison A. Barto, Editor(s)

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