| 摘要 |
PURPOSE:To improve mirror properties on a substrate surface, by providing a forming process for silica coating film by a wet coating after a blank manufacturing process. CONSTITUTION:Al or Al alloy is used as a substrate 21 and it is processed platelike in an equilateral dodecagon. An axial hole 22 is formed at the center part. The circumferential twelve surfaces serve as a reflecting surface 23. A silica coating film 24 is stuck on the surface of the above-mentioned substrate 21 by a wet coating method to make a smooth surface. The film 24 is transparent and glasslike. A reflecting film 25 and a protecting film 26 are formed on said film by a vacuum-deposition method. |
