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Proceedings Paper • Open Access

Directly polished lightweight aluminum mirror

Paper Abstract

During the last ten years, Astron has been a major contractor for the design and manufacturing of astronomical instruments for Space- and Earth based observatories, such as VISIR, MIDI, SPIFFI, X-Shooter and MIRI. Driven by the need to reduce the weight of optically ultra-stiff structures, two promising techniques have been developed in the last years: ASTRON Extreme Lightweighting [1][2] for mechanical structures and an improved Polishing Technique for Aluminum Mirrors. Using one single material for both optical components and mechanical structure simplifies the design of a cryogenic instrument significantly, it is very beneficial during instrument test and verification, and makes the instrument insensitive to temperature changes. Aluminum has been the main material used for cryogenic optical instruments, and optical aluminum mirrors are generally diamond turned. The application of a polishable hard top coating like nickel removes excess stray light caused by the groove pattern, but limits the degree of lightweighting of the mirrors due to the bi-metal effect. By directly polishing the aluminum mirror surface, the recent developments at Astron allow for using a non-exotic material for light weighted yet accurate optical mirrors, with a lower surface roughness (~1nm RMS), higher surface accuracy and reduced light scattering. This paper presents the techniques, obtained results and a global comparison with alternative lightweight mirror solutions. Recent discussions indicate possible extensions of the extreme light weight technology to alternative materials such as Zerodur or Silicon Carbide.

Paper Details

Date Published: 21 November 2017
PDF: 8 pages
Proc. SPIE 10566, International Conference on Space Optics — ICSO 2008, 105660P (21 November 2017); doi: 10.1117/12.2308200
Show Author Affiliations
Rik ter Horst, NOVA-ASTRON (Netherlands)
Niels Tromp, NOVA-ASTRON (Netherlands)
Menno de Haan, NOVA-ASTRON (Netherlands)
Ramon Navarro, NOVA-ASTRON (Netherlands)
Lars Venema, ASTRON (Netherlands)
Johan Pragt, ASTRON (Netherlands)


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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