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Proceedings Paper

Manufacture of the combined primary and tertiary mirrors of the Large Synoptic Survey Telescope
Author(s): H. M. Martin; R. G. Allen; J. H. Burge; B. Cuerden; W. Gressler; W. Hubler; D. Ketelsen; D. W. Kim; J. S. Kingsley; K. Law; P. A. Strittmatter; M. T. Tuell; S. C. West; C. Zhao; P. Zhou
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Paper Abstract

The Steward Observatory Mirror Lab is nearing completion of the combined primary and tertiary mirrors of the Large Synoptic Survey Telescope. Fabrication of the combined mirror requires simulation of an active-optics correction that affects both mirror surfaces in a coordinated way. As is common for large mirrors, the specification allows correction of large-scale figure errors by a simulated bending of the substrate with the 156 mirror support actuators. Any bending affects both mirrors, so this active-optics correction is constrained by the requirement of bending the substrate so both mirrors meet their figure specifications simultaneously. The starting point of the simulated correction must be measurements of both mirrors with the substrate in the same shape, i. e. the same state of mechanical and thermal stress. Polishing was carried out using a 1.2 m stressed lap for smoothing and large-scale figuring, and a set of smaller passive rigid-conformal laps on an orbital polisher for deterministic small-scale figuring. The primary mirror is accurate to about 25 nm rms surface after the active-optics correction, while work continues toward completion of the tertiary.

Paper Details

Date Published: 7 August 2014
PDF: 8 pages
Proc. SPIE 9151, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation, 915125 (7 August 2014); doi: 10.1117/12.2057317
Show Author Affiliations
H. M. Martin, Steward Observatory, The Univ. of Arizona (United States)
R. G. Allen, Steward Observatory, The Univ. of Arizona (United States)
J. H. Burge, Steward Observatory, The Univ. of Arizona (United States)
College of Optical Sciences, The Univ. of Arizona (United States)
B. Cuerden, Steward Observatory, The Univ. of Arizona (United States)
W. Gressler, National Optical Astronomy Observatory (United States)
W. Hubler, Steward Observatory, The Univ. of Arizona (United States)
D. Ketelsen, Steward Observatory, The Univ. of Arizona (United States)
D. W. Kim, College of Optical Sciences, The Univ. of Arizona (United States)
J. S. Kingsley, Steward Observatory, The Univ. of Arizona (United States)
K. Law, Steward Observatory, The Univ. of Arizona (United States)
P. A. Strittmatter, Steward Observatory, The Univ. of Arizona (United States)
M. T. Tuell, Steward Observatory, The Univ. of Arizona (United States)
S. C. West, Steward Observatory, The Univ. of Arizona (United States)
C. Zhao, College of Optical Sciences, The Univ. of Arizona (United States)
P. Zhou, 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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