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Proceedings Paper

Lightweighted secondary mirror for the United Kingdom Infrared Telescope
Author(s): Ralf-Rainer Rohloff; Eckhart Pitz; Timothy G. Hawarden; Nicholas P. Rees; Eli Ettedgui-Atad; Horst W. Kaufmann; Lutz Schmadel
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Paper Abstract

The paper describes the manufacture and testing of a lightweighted Zerodur secondary mirror for the United Kingdom Infrared Telescope on Mauna Kea, Hawaii. The 313 mm diameter mirror is mounted on a Piezo platform for fast tip/tilt corrections. Therefore, the mirror mass has to be minimized to achieve high dynamic properties of the adaptive tip/tilt platform. The goal was to test the convex secondary without large auxiliary optics (Hindle sphere). We measured the mirror through the back surface using a small null lens system. A special transparent and highly homogeneous Zerodur was used for this purpose. We demonstrate that grinding a honeycomb structure and acid-etching of the back side of the mirror does not affect the figure of the polished convex surface.

Paper Details

Date Published: 29 October 1999
PDF: 8 pages
Proc. SPIE 3785, Advanced Telescope Design, Fabrication, and Control, (29 October 1999); doi: 10.1117/12.367613
Show Author Affiliations
Ralf-Rainer Rohloff, Max-Planck-Institut fuer Astronomie (Germany)
Eckhart Pitz, Max-Planck-Institut fuer Astronomie (Germany)
Timothy G. Hawarden, Joint Astronomy Ctr. (United Kingdom)
Nicholas P. Rees, Joint Astronomy Ctr. (United States)
Eli Ettedgui-Atad, Royal Observatory Edinburgh (United Kingdom)
Horst W. Kaufmann, Kaufmann Praezisionsoptik (Germany)
Lutz Schmadel, Astronomisches Rechen-Institut Heidelberg (Germany)


Published in SPIE Proceedings Vol. 3785:
Advanced Telescope Design, Fabrication, and Control
William Roybal, Editor(s)

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