| 摘要 |
PURPOSE:To improve strength, hardness and durability by forming a diamond type film on the surface of a light transmittable calcium fluoride base material. CONSTITUTION:The diamond type film is formed on at least one surface of the light transmittable calcium fluoride base material. The diamondlike carbon film and crystalline diamond film are the chemically stable and extremely hard films having 3,000-10,000kg/mm<2> hardness. The scratching resistance and rain erosion resistance of the surface of the calcium fluoride base material having low hardness are, therefore, improved by coating the surface of said material with said diamond type film. The satisfactory light transmittability is thereby maintained for a long period of time even under severe service conditions. |
