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Proceedings Paper • Open Access

Highly light-weighted ZERODUR mirrors
Author(s): Stéphanie Behar-Lafenetre; Thierry Lasic; Roger Viale; Jean-Claude Mathieu; Eric Ruch; Michel Tarreau; Pierre Etcheto

Paper Abstract

Due to more and more stringent requirements for observation missions, diameter of primary mirrors for space telescopes is increasing. Difficulty is then to have a design stiff enough to be able to withstand launch loads and keep a reasonable mass while providing high opto-mechanical performance. Among the possible solutions, Thales Alenia Space France has investigated optimization of ZERODUR mirrors. Indeed this material, although fragile, is very well mastered and its characteristics well known. Moreover, its thermo-elastic properties (almost null CTE) is unequalled yet, in particular at ambient temperature. Finally, this material can be polished down to very low roughness without any coating. Light-weighting can be achieved by two different means : either optimizing manufacturing parameters or optimizing design (or both). Manufacturing parameters such as walls and optical face thickness have been improved and tested on representative breadboards defined on the basis of SAGEM-REOSC and Thales Alenia Space France expertise and realized by SAGEM-REOSC. In the frame of CNES Research and Technology activities, specific mass has been decreased down to 36 kg/m2. Moreover SNAP study dealt with a 2 m diameter primary mirror. Design has been optimized by Thales Alenia Space France while using classical manufacturing parameters – thus ensuring feasibility and costs. Mass was decreased down to 60 kg/m2 for a gravity effect of 52 nm. It is thus demonstrated that high opto-mechanical performance can be guaranteed with large highly lightweighted ZERODUR mirrors.

Paper Details

Date Published: 21 November 2017
PDF: 8 pages
Proc. SPIE 10566, International Conference on Space Optics — ICSO 2008, 105660O (21 November 2017); doi: 10.1117/12.2308286
Show Author Affiliations
Stéphanie Behar-Lafenetre, Thales Alenia Space (France)
Thierry Lasic, Thales Alenia Space (France)
Roger Viale, Thales Alenia Space (France)
Jean-Claude Mathieu, Thales Alenia Space (France)
Eric Ruch, Sagem Defense Sercurite (France)
Michel Tarreau, Sagem Defense Securite (France)
Pierre Etcheto, Ctr. National d'Études Spatiales (France)

Published in SPIE Proceedings Vol. 10566:
International Conference on Space Optics — ICSO 2008
Josiane Costeraste; Errico Armandillo; Nikos Karafolas, Editor(s)

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