Prototype segments polishing and testing for ELT M1

Jacques Rodolfo; Laurent Chouarche; Gilles Chaussat; Anne-Laure Hamy; Jean-Louis Carel; Bruno Pernet; Jacques Billet; Hervé Leplan; Eric Ruch

doi:10.1117/12.925417

13 September 2012 Prototype segments polishing and testing for ELT M1

Jacques Rodolfo, Laurent Chouarche, Gilles Chaussat, Anne-Laure Hamy, Jean-Louis Carel, Bruno Pernet, Jacques Billet, Hervé Leplan, Eric Ruch

Author Affiliations +

Proceedings Volume 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II; 845023 (2012) https://doi.org/10.1117/12.925417
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

Sagem – Reosc has been awarded by ESO a contract for the manufacturing and testing of seven prototype segments of the E-ELT primary mirror in 2008. The purpose of this contract was to demonstrate the ability to produce aspherical off-axis hexagonal segments with very little edge effect and very high quality wavefront error and plan the production of the 931 segments needed for the primary mirror and spares. The manufacturing of the prototype segments is now completed. They have been delivered. Sagem has achieved for the best segment integrated on its support an overall surface error of 23 nm RMS and 6 nm RMS after removal of the allowed amount of Focus, Astigmatism and Trefoil. This article will present the process developped by Sagem and its performance. Sagem has also assessed the performances of an alternate manufacturing process based on the polishing of the segments under stress conditions (Stress Mirror Polishing). The results obtained by this process will also be presented.

Citation Download Citation

Jacques Rodolfo, Laurent Chouarche, Gilles Chaussat, Anne-Laure Hamy, Jean-Louis Carel, Bruno Pernet, Jacques Billet, Hervé Leplan, and Eric Ruch "Prototype segments polishing and testing for ELT M1", Proc. SPIE 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II, 845023 (13 September 2012); https://doi.org/10.1117/12.925417

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