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Proceedings Paper

Design and fabrication of a 3m class light weighted mirror blank for the E-ELT M5
Author(s): Ralf Jedamzik; Volker Seibert; Armin Thomas; Thomas Westerhoff; Michael Müller; Marc Cayrel
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Paper Abstract

In the recent past, SCHOTT has demonstrated its ability to manufacture large light weighted ZERODUR® mirror blanks for telescope projects like the GREGOR solar-telescope, for example. In 2010, SCHOTT was commissioned with a study aimed at developing a design for the M5 mirror blank of the ESO E-ELT. The tip and tilt M5 mirror of the European Extremely Large Telescope (E-ELT) requires a demanding approach in light weighting. The approximately 3.1 m x 2.5 m elliptical plano mirror is specified to a weight of less than 500 kg with high Eigenfrequencies and low deformation under different inclination angles. The study was divided into two parts. The first part focused on coming up with an optimized light weighted design with respect to performance and processability with finite element modeling. In the second part of the study, a concept for the processing sequence including melting, cold-processing, acid etching and handling of the M5 blank was developed. By producing a prototype section, SCHOTT demonstrated its ability to manufacture the demanding features, including pockets 350 mm in depth, thin walls and sloped pocket bottoms. This paper outlines the results of the design work, processing concept and demonstrator fabrication.

Paper Details

Date Published: 26 September 2011
PDF: 11 pages
Proc. SPIE 8126, Optical Manufacturing and Testing IX, 812607 (26 September 2011); doi: 10.1117/12.891521
Show Author Affiliations
Ralf Jedamzik, SCHOTT AG (Germany)
Volker Seibert, SCHOTT AG (Germany)
Armin Thomas, SCHOTT AG (Germany)
Thomas Westerhoff, SCHOTT AG (Germany)
Michael Müller, European Southern Observatory (Germany)
Marc Cayrel, European Southern Observatory (Germany)

Published in SPIE Proceedings Vol. 8126:
Optical Manufacturing and Testing IX
James H. Burge; Oliver W. Fähnle; Ray Williamson, Editor(s)

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