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Proceedings Paper

Applications of computer-generated holograms for interferometric measurement of large aspheric optics
Author(s): James H. Burge
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Paper Abstract

Interferometric optical testing using computer-generated holograms (CGH's) has proven to give highly accurate measurements of aspheric surfaces. New applications of CGH interferometry were developed to support the fabrication of the large, steep mirrors required by the next generation ground-based telescopes. A new test to certify null correctors was designed and implemented that uses small CGH's fabricated onto flat surfaces. This test solves the difficult problem of verifying the accuracy of the null correctors that are used for measuring primary mirrors. Several new techniques for hologram fabrication have been explored for this application. A second new use of CGH's was developed for measuring convex secondary mirrors using test plates with holograms fabricated onto concave spherical reference surfaces. This test provides efficient and accurate measurement of large aspheric convex mirrors. A polar coordinate laser writing machine was built for fabricating these patterns onto curved optical surfaces up to 1.8 meters in diameter and as fast as f/1. These powerful new techniques have been implemented and optimized at the Steward Observatory Mirror Laboratory to guide mirror polishing for large telescope projects. They can also be readily applied for measuring small aspheres to high accuracy.

Paper Details

Date Published: 2 August 1995
PDF: 12 pages
Proc. SPIE 2576, International Conference on Optical Fabrication and Testing, (2 August 1995); doi: 10.1117/12.215609
Show Author Affiliations
James H. Burge, Steward Observatory/Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 2576:
International Conference on Optical Fabrication and Testing
Toshio Kasai, Editor(s)

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