26 September 2011 ZERODUR for stress mirror polishing
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Abstract
Stress mirror polishing is considered as one of several polishing technologies for the generation of the aspherical shaped primary mirror segments of the thirty meter telescope (TMT). For stress mirror polishing it is essential to precisely know the elastic response of glass ceramic substrate materials under a given deformation load. In the past it was experimentally shown that glass ceramics do not respond instantaneously to loading and unloading conditions, this effect was called "delayed elasticity." Recently SCHOTT has shown that it is possible to use a model to predict the characteristic thermal expansion behaviour of individual ZERODUR® batches for a given temperature profile. A similar approach will be used to predict the delayed elastic behavior of ZERODUR® under time dependent loads. In this presentation the delayed elasticity effect of ZERODUR® is reviewed. The delayed elastic response of the material to load conditions is shown and discussed. First results of a model approach based on experimental results and tools that have been built up for the modelling of the delayed elasticity effect of ZERODUR® will be presented.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ralf Jedamzik, Clemens Kunisch, Thomas Westerhoff, "ZERODUR for stress mirror polishing", Proc. SPIE 8126, Optical Manufacturing and Testing IX, 812606 (26 September 2011); doi: 10.1117/12.894421; https://doi.org/10.1117/12.894421
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