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Proceedings Paper

Segmented mirrors for DGT
Author(s): Peter Ruemmer; Ernst-Dieter Knohl; Immo Appenzeller; Christoph F. Kuehne; K. Bahner
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Paper Abstract

The ArbeitsGemeinschaft Deutsches GrossTeleskop (AG-DG1) is concerned with the realization of a telescope in the 12 m class and has charged Carl Zeiss with a feasibility study concerning the optical figuring of large mirror blanks. The state of the art technology of spin-cast ZERODIJR mirror substrates at Schott Glaswerke allows fabrication of thin meniscus blanks up to 8.2 m in diameter. Therefore the primary is to be assembled from several single segments and should be optimized for the segmentation and the polishing process. Two methods of segmenting the primary mirror are considered: Combining either four 90-degree segments or a central 8 m monolith surrounded with 12 segments of 3Odegree each. Several methods of figuring and testing of out-of-axis segments are discussed. Techniques for a stiff connection of single segments are examined. Basic considerations of the axial support system of nonrotational segments are presented. The printthrough effect on the mirror's surface is calculated with varying pad distances and with varying geometry of the support points. The Membran Tool Processing (MTP) developed by Carl Zeiss will be used for polishing the mirror blank. With the active controlled strip tool large areas can be asphencal shaped and polished in a much shorter time than with the conventional technology.

Paper Details

Date Published: 1 August 1990
PDF: 11 pages
Proc. SPIE 1271, Adaptive Optics and Optical Structures, (1 August 1990); doi: 10.1117/12.20415
Show Author Affiliations
Peter Ruemmer, Carl Zeiss (Germany)
Ernst-Dieter Knohl, Carl Zeiss (Germany)
Immo Appenzeller, AG-DGT (Germany)
Christoph F. Kuehne, AG-DGT (Germany)
K. Bahner, AG-DGT (Germany)

Published in SPIE Proceedings Vol. 1271:
Adaptive Optics and Optical Structures
Joachim J. Schulte-in-den-Baeumen; Robert K. Tyson, Editor(s)

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