| 摘要 |
PROBLEM TO BE SOLVED: To obtain an infrared antireflection film excellent in durability even in a severe environment while ensuring antireflection function by using a medium refractive index material in the 1st layer of an infrared antireflection film from the substrate side and a high refractive index material in the 2nd layer and laminating a film of Al2 O3 as a medium refractive index material as the outer most layer. SOLUTION: An infrared antireflection film is formed on an infrared optical substrate. A medium refractive index material is used in a 1st layer of the film from the substrate side, a high refractive index material is used-in a 2nd layer, and a film of Al2 O3 as a medium refractive index material is used is the outermost layer, and these layers are laminated with each other. In such a case, material selected from a group consisting of Ge, Si, Zn and ZnSe is preferable, and A2 O2 SiO, Zn, ZnSe and the like are embodied as the medium refractive index material which is used in the 1st layer and Ge, Si and the like are embodies as the high refractive index material which is used in the 2nd layer. |
