F-molding: A New Production Method for Largely Aspherical Mirrors of Cordierite

Cordierite is a rigid low thermal expansion coefficient ceramic equivalent to that of low thermal expansion glass but with voids due to forming with raw material powder. To overcome this problem, we propose Flexible Molding (F-molding) as our new fabrication method. With F-molding, the raw material powder is converted to liquid slurry, which is poured into a resin mold, solidified, and directly formed into near net design of a mirror. The mold prepared from F-molding is an effective tool for processing multiple volumes of identical structures such as those used in segmented mirror designs. We introduce details of our fabrication method in F-molding mirror and report its measurement results of optical performances with a 270mm diameter sample