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Proceedings Paper

Fabrication and measured quality of the MMT primary mirror
Author(s): Hubert M. Martin; R. G. Allen; James Roger P. Angel; James H. Burge; Warren B. Davison; Scott T. DeRigne; Lee R. Dettmann; Dean A. Ketelsen; W. Cary Kittrell; Stephen M. Miller; Peter A. Strittmatter; Steve C. West
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Paper Abstract

The primary mirror for the Multiple Mirror Telescope Conversion is the first 6.5 m honeycomb sandwich mirror cast and polished by the Steward Observatory Mirror Lab. We describe the optical fabrication and testing of the f/1.25 paraboloid, and present the final measurements of figure accuracy and inferred image quality. Figuring was performed with a 1.2 m stressed lap--which bends under active control to match the local curvature of the optical surface--and a variety of small passive tools. The mirror was pressurized to compensate for polishing loads and thereby eliminate print-through of the honeycomb structure. The net result is a smoother surface on scales of 5 - 20 cm than has been achieved on previous honeycomb sandwich mirrors. The figure was measured with IR and visible interferometers, using refractive null correctors to compensate 810 microns of aspheric departure. The final measurements were used to calculate synthetic stellar images in a variety of seeing conditions.

Paper Details

Date Published: 25 August 1998
PDF: 11 pages
Proc. SPIE 3352, Advanced Technology Optical/IR Telescopes VI, (25 August 1998); doi: 10.1117/12.319255
Show Author Affiliations
Hubert M. Martin, Steward Observatory/Univ. of Arizona (United States)
R. G. Allen, Steward Observatory/Univ. of Arizona (United States)
James Roger P. Angel, Steward Observatory/Univ. of Arizona (United States)
James H. Burge, Steward Observatory/Univ. of Arizona (United States)
Warren B. Davison, Steward Observatory/Univ. of Arizona (United States)
Scott T. DeRigne, Steward Observatory/Univ. of Arizona (United States)
Lee R. Dettmann, Steward Observatory/Univ. of Arizona (United States)
Dean A. Ketelsen, Steward Observatory/Univ. of Arizona (United States)
W. Cary Kittrell, Steward Observatory/Univ. of Arizona (United States)
Stephen M. Miller, Steward Observatory/Univ. of Arizona (United States)
Peter A. Strittmatter, Steward Observatory/Univ. of Arizona (United States)
Steve C. West, Steward Observatory/Univ. of Arizona (United States)


Published in SPIE Proceedings Vol. 3352:
Advanced Technology Optical/IR Telescopes VI
Larry M. Stepp, Editor(s)

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