| 摘要 |
PURPOSE:To provide high durability and substantially high reflectivity and to enable control of the dependency of incident angle of incident light by high-speed rotation by forming a thin film consisting of a metal having high reflectivity on the specular surface of a metallic blank material and forming further at least two layers of thin dielectric films thereon. CONSTITUTION:A blank material 1 is aluminum which itself has high reflectivity and the surface thereof is worked to a specular surface by diamond cutting. Such specular surface is thoroughly chemically cleaned and is further cleaned by ion impact such as ion bombardment or the like in a vacuum deposition device. A thin chromium film 2 is formed on the specular surface by a vapor deposition method and further a thin copper film 3 is formed thereon by a similar method. A thin film 4 consisting of Al2O3 and a thin film 5 consisting of TiO2 are hard-coated thereon in this oder by a vacuum deposition method. |
