| 摘要 |
PURPOSE:To attain excellent heat resistance and to prevent generation of a crack even if an optical part is heated at the time of framing by laminating a first layer composed of silicon dioxide, a second layer composed of a specific three-layer equivalent film, a third layer composed of the mixture of a specific metallic oxide, and a fourth layer composed of silicon dioxide, in order, from a base material. CONSTITUTION:The first layer 1 composed of the silicon dioxide, the second layer composed of the three-layer equivalent film composed of a tantalum pentoxide or yttrium trioxide layer, a silicon dioxide layer, and the pentoxide or yttrium trioxide layer, the third layer composed of a mixture of the metallic oxide >=1 kind selected out of titanium dioxide, tantalum pentoxide, zirconium dioxide, and yttrium trioxide, and the fourth layer composed of the silicon dioxide, are sequentially laminated on a transparent synthetic resin base material, to form the optical part. At this time, the evaporation film of the silicon dioxide has strong sticking force with a plastic and high hardness compared with other evaporation films, and the third layer by the titanium dioxide and the titanium pentoxide has high heat resistance. Thus, the optical part has excellent heat resistance, and the crack does not generate even if the optical part is heated at the time of the framing of a glass. |
