title: Quality evaluation of spaceborne SiC mirrors (I): analytical examination of the effects on mirror accuracy by variation in the thermal expansion property of the mirror surface.
abstract: The Japan Aerospace Exploration Agency has studied a large-scale lightweight mirror constructed of reaction-bonded silicon carbide-based material as a key technology in future astronomical and earth observation missions. The authors selected silicon carbide as the promising candidate due to excellent characteristics of specific stiffness and thermal stability. One of the most important technical issues for large-scale ceramic components is the uniformity of the material's property, depending on part and processing. It might influence mirror accuracy due to uneven thermal deformation. The authors conducted systematic case studies for the conditions of CTE by finite element analysis to know the typical influence of material property nonuniformity on mirror accuracy and consequently derived a comprehensive empirical equation for the series of CTE's main factors. In addition, the authors computationally reproduced the mirror accuracy profile of a small prototype mirror shown in cryogenic testing and hereby verified wide-range practical computational evaluation technology of mirror accuracy.
authors.affiliation: Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, Mitaka-shi, Tokyo, Japan. kotani.masaki@jaxa.jp
authors.forename: Masaki
authors.initials: M
authors.lastname: Kotani
authors.forename: Tadashi
authors.initials: T
authors.lastname: Imai
authors.forename: Haruyoshi
authors.initials: H
authors.lastname: Katayama
authors.forename: Yukari
authors.initials: Y
authors.lastname: Yui
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Tange
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Kaneda
authors.forename: Takao
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Keigo
authors.initials: K
authors.lastname: Enya