Quality evaluation of spaceborne SiC mirrors (II): evaluation technology for mirror accuracy using actual measurement data of samples cut out from a mirror surface.

The authors studied the quality evaluation technology of a spaceborne large-scale lightweight mirror that was made of silicon carbide (SiC)-based material. To correlate the material property of a mirror body and the mirror accuracy, the authors evaluated the mirror surface deviation of a prototype mirror by inputting actually measured coefficient of thermal expansion (CTE) data into a finite element analysis model. The CTE data were obtained by thermodilatometry using a commercial grade thermal dilatometer for the samples cut from all over the mirror surface.

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.

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.