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29 January 2004 Forming mandrels for x-ray telescopes made of modified Zerodur
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For the next generation of X-ray observatories (CONSTELLATION-X and XEUS) a mass production of glass mirror segments is considered. The mirror substrates (SCHOTT D263 and SCHOTT BOROFLOAT 33) will be pre-shaped in a high temperature slumping process by use of precision forming mandrels. SCHOTT GLAS developed the glass ceramic material ZERODUR K20 to meet the requirements of these mandrels. The new material is a modification of the well-known ZERODUR. A heat driven transformation thereby changes the crystalline phase from high-quartz to keatite structure. The resulting ZERODUR K20 exhibits an increased stability at high temperatures of up to 850°C and a low thermal expansion coefficient (CTE) of approximately 20•10-7 K-1 (20°-700°C). Numerical simulations of the slumping process based on experimental parameters of Zerodur K20 and the mirror substrate materials are presented.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thorsten Doehring, Ralf Jedamzik, Peter Hartmann, Hauke Esemann, and Clemens Kunisch "Forming mandrels for x-ray telescopes made of modified Zerodur", Proc. SPIE 5168, Optics for EUV, X-Ray, and Gamma-Ray Astronomy, (29 January 2004);


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