Figuring, polishing, metrology, and performance: analyses of Wolter type 1 forming mandrels for the Constellation-X mirror development program

Wilhelm J. Egle; Axel Matthes; Georg Willma; Alexander Ilg; Andy Schmidt; Andreas Seifert

doi:10.1117/12.563521

11 October 2004 Figuring, polishing, metrology, and performance-analyses of Wolter type 1 forming mandrels for the Constellation-X mirror development program

Wilhelm J. Egle, Axel Matthes, Georg Willma, Alexander Ilg, Andy Schmidt, Andreas Seifert

Author Affiliations +

Proceedings Volume 5488, UV and Gamma-Ray Space Telescope Systems; (2004) https://doi.org/10.1117/12.563521
Event: SPIE Astronomical Telescopes + Instrumentation, 2004, Glasgow, United Kingdom

Abstract

Constellation-X, NASA's next major X-ray observatory, is planned to be launched in 2012/2013. Each of the four identical spacecraft contains a large diameter, spectroscopic X-ray telescope (SXT). The mirror assembly is compsed of many densely nested Wolter type 1 mirror reflectors, having segment angles of 30 or 60 degrees. The reflectors will be made of thin, accurately shaped glass sheets, onto which the reflective mirror surface is replicated from high precision, super polished Zerodur mandrels. One key issue for high-performance mirrors is the exact shape of the glass substrates. They are produced at NASA/GSFC by a dedicated hot forming process (slumping) from precision forming mandrels. The hot forming process requires special materials for the glass substrates and the forming mandrels. In this paper we report on figuring (precision machining), polishing, metrology and performance analyses of Wolter type 1 forming mandrels. The mandrels are characterized by the following features: Mandrel dimensions: 450 x 640 mm²; radius of curvature: ~800 mm; segment angle: ~40 deg; shape: hyperboloid or paraboloid; material: Zerodur K20 (Keatite) or fused silica (quartz).

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Wilhelm J. Egle, Axel Matthes, Georg Willma, Alexander Ilg, Andy Schmidt, and Andreas Seifert "Figuring, polishing, metrology, and performance-analyses of Wolter type 1 forming mandrels for the Constellation-X mirror development program", Proc. SPIE 5488, UV and Gamma-Ray Space Telescope Systems, (11 October 2004); https://doi.org/10.1117/12.563521

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