| 摘要 |
PROBLEM TO BE SOLVED: To obtain an antireflection film having good antireflection characteristics in a UV ray region at specified or shorter wavelength by forming specified high refractive index layers and low refractive index layers on a substrate, specifying the designed center wavelength in a specified wavelength range, and controlling the optical film thickness of an overcoat film to satisfy specified conditions. SOLUTION: Plural layers of high refractive index layers containing Al2O3 and low refractive index layers containing A1F3 are formed on a substrate G. The center wavelength λ0 is designed for the rays from 160 nm wavelength to 300 nm wavelength. The finish layer adjacent to air is an overcoat film made of CaF2, and the optical film thickness DC of the overcoat film satisfies λ0/20<DC<λ0/5. Thus, by laminating high refractive index layers, low refractive index layers, and overcoat film to proper optical film thickness on the substrate, the antireflection film can be obtd. with good productivity and the obtd. film shows good antireflection characteristics in a wide UV ray region at <300 nm wavelength. |
