Development of the SOFIA silicon carbide secondary mirror

Michel Fruit; Pascal Antoine; Jean-Luc Varin; Hermann Bittner; Matthias Erdmann

doi:10.1117/12.458632

3 March 2003 Development of the SOFIA silicon carbide secondary mirror

Michel Fruit, Pascal Antoine, Jean-Luc Varin, Hermann Bittner, Matthias Erdmann

Proceedings Volume 4857, Airborne Telescope Systems II; (2003) https://doi.org/10.1117/12.458632
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

Abstract

The SOFIA telescope is ajoint NASA-DLR project for a 2.5 m airborne Stratospheric Observatory for IR Astronomy to be flown in a specially adapted Boeing 747 SP plane, Kayser-Threde being resopinsible for the development of the Telescope Optics. The φ 352 mm Secondary Mirror is mounted ona chopping mechanism to allow avoidance of background noise during IR observations. Stiffness associated to lightness is a major demand for such a mirror to achieve high frequency chopping. This leads to select SIlicon Carbide for the mirror blank. Its development has been run by the ASTRIUM/BOOSTEC joint venture SiCSPACE, taking full benefit of the instrinsic properties of the BOOSTEC SiC-100 sintered material, associated to qualified processes specifically developed for space borne mirrors by ASTRIUM. Achieved performances include a low mass of 1.97 kg, a very high stiffness with a first resonant frequency of 1865 Hz and a measured optical surface accuracy of 39 nm rms, using Ion Beam Figuring. It is proposed here to present the major design features of the SOFIA Secondary Mirror, highlighting the main advantages of using Silicon Carbide, the main steps of its development and the achieved optomechanical performances of the developed mirror.

Citation Download Citation

Michel Fruit, Pascal Antoine, Jean-Luc Varin, Hermann Bittner, and Matthias Erdmann "Development of the SOFIA silicon carbide secondary mirror", Proc. SPIE 4857, Airborne Telescope Systems II, (3 March 2003); https://doi.org/10.1117/12.458632

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