Scanning pentaprism measurements of off-axis aspherics

Peng Su; James H. Burge; Brian Cuerden; Jose Sasian; Hubert M. Martin

doi:10.1117/12.789588

25 July 2008 Scanning pentaprism measurements of off-axis aspherics

Peng Su, James H. Burge, Brian Cuerden, Jose Sasian, Hubert M. Martin

Proceedings Volume 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation; 70183T (2008) https://doi.org/10.1117/12.789588
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

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.

Citation Download Citation

Peng Su, James H. Burge, Brian Cuerden, Jose Sasian, and Hubert M. Martin "Scanning pentaprism measurements of off-axis aspherics", Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 70183T (25 July 2008); https://doi.org/10.1117/12.789588

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