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Proceedings Paper

Primary mirror system for the first Magellan telescope
Author(s): Hubert M. Martin; R. G. Allen; Brian Cuerden; Scott T. DeRigne; Lee R. Dettmann; Dean A. Ketelsen; Stephen M. Miller III; Giancarlo Parodi; S. Warner
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Paper Abstract

We describe the optical fabrication and the active support system of the 6.5 m f/1.25 primary mirror for the first Magellan telescope. 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 small passive tools. The figure was measured with IR and visible interferometers, using refractive null lenses to compensate 810 microns of aspheric departure. After subtraction of Seidel astigmatism and spherical aberration, the finished mirror is accurate to 14 nm rms surface and has an encircled energy of 80% in 0.06' diameter at 500 nm. The mirror was integrated with its active support system in the laboratory, and support forces were adjusted to optimize the figure. The optimization was performed by singular value decomposition of the influence functions into normal bending modes. Using the first 20 modes and a maximum correction force of 46 N, the surface accuracy is 24 nm rms with 80% of the light in 0.11' diameter.

Paper Details

Date Published: 20 July 2000
PDF: 12 pages
Proc. SPIE 4003, Optical Design, Materials, Fabrication, and Maintenance, (20 July 2000); doi: 10.1117/12.391497
Show Author Affiliations
Hubert M. Martin, Steward Observatory/Univ. of Arizona (United States)
R. G. Allen, Steward Observatory/Univ. of Arizona (United States)
Brian Cuerden, 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)
Stephen M. Miller III, Steward Observatory/Univ. of Arizona (United States)
Giancarlo Parodi, BCV Progetti Srl (Italy)
S. Warner, Steward Observatory/Univ. of Arizona (United States)


Published in SPIE Proceedings Vol. 4003:
Optical Design, Materials, Fabrication, and Maintenance
Philippe Dierickx, Editor(s)

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