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Proceedings Paper

Scanning pentaprism measurements of off-axis aspherics
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Paper Abstract

The pentaprism test is based on the property of a paraboloidal surface where all rays parallel to the optical axis will go through its focal point. We have developed a scanning pentaprism system that exploits this geometry to measure off-axis paraboloidal mirrors such as those for the Giant Magellan Telescope primary mirror. Extension of the pentaprism test to off-axis mirrors requires special attention to field effects that can be ignored in the measurement of an axisymmetric mirror. The test was demonstrated on a 1. -m diameter off-axis mirror and proved to have about 50nm rms surface accuracy. This paper gives detailed performance results for the measurement of the 1.7 m mirror, and designs and analysis for the test of the GMT segments.

Paper Details

Date Published: 25 July 2008
PDF: 10 pages
Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 70183T (25 July 2008); doi: 10.1117/12.789588
Show Author Affiliations
Peng Su, College of Optical Sciences, The Univ. of Arizona (United States)
James H. Burge, College of Optical Sciences, The Univ. of Arizona (United States)
Steward Observatory, The Univ. of Arizona (United States)
Brian Cuerden, Steward Observatory, The Univ. of Arizona (United States)
Jose Sasian, College of Optical Sciences, The Univ. of Arizona (United States)
Hubert M. Martin, Steward Observatory, The Univ. of Arizona (United States)


Published in SPIE Proceedings Vol. 7018:
Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation
Eli Atad-Ettedgui; Dietrich Lemke, Editor(s)

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