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Selection considerations for astronomical mirror materials: Trade criteria

Increasingly, the optimal mirror material trade must reach well beyond textbook material attributes, and consider the richness and applicability of underlying statistically meaningful engineering data. The trade itself will have profound cost and complexity impact in the system implementation, from assembly, integration and test (AIT) through gravity and dynamic loading, and into operation under those influencing factors. Material selection is a multi-parameter decision, having significant performance and cost implications on higher level system attributes. We note that for most situations, an astronomical optical telescope will not be isothermal, and strategies based on this assumption are limited where ultimate performance is expected. Attributes like inhomogeneity or anisotropy of thermal characteristics can dominate. We summarize material attributes that should be considered in material selection, and reference these attributes to those of ZERODUR.