Optical and thermal design of the main optic of the solar telescope GREGOR

Reiner Volkmer; Oskar von der Luhe; Dirk Soltau; Peter Emde; Matthias Krodel; Norbert Pailer; Eberhardt Wiehr

doi:10.1117/12.506710

12 December 2003 Optical and thermal design of the main optic of the solar telescope GREGOR

Reiner Volkmer, Oskar von der Luhe, Dirk Soltau, Peter Emde, Matthias Krodel, Norbert Pailer, Eberhardt Wiehr

Proceedings Volume 5179, Optical Materials and Structures Technologies; (2003) https://doi.org/10.1117/12.506710
Event: Optical Science and Technology, SPIE's 48th Annual Meeting, 2003, San Diego, California, United States

Abstract

The optical and thermal design of the 1.5 m solar telescope GREGOR is presented. The three first main mirrors of GREGOR will be made from Cesic, a silicon carbide material. One major constraint of large solar telescopes is the thermal load of the structure and the mirrors. The mirrors are heated by the solar radiation and introduce potentially harmful mirror seeing. GREGOR will use an active mirror cooling system and an open telescope structure to reduce these negative effects. A thermal analysis shows that the equilibrium temperature of the Cesic Mirror without active cooling is 6° above ambient temperature. Additional cooling will reduce the temperature difference of the optical surface and ambient air to below 0.1° K. With tempered airflow (about 2.5 m³/s per square meter mirror surface) the temperature gradient on the surface of the face sheet is less than 0.1°K. The telescope will have an open structure and a complete retractable dome to support mirror and structure cooling by wind.

Citation Download Citation

Reiner Volkmer, Oskar von der Luhe, Dirk Soltau, Peter Emde, Matthias Krodel, Norbert Pailer, and Eberhardt Wiehr "Optical and thermal design of the main optic of the solar telescope GREGOR", Proc. SPIE 5179, Optical Materials and Structures Technologies, (12 December 2003); https://doi.org/10.1117/12.506710

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