| 摘要 |
PROBLEM TO BE SOLVED: To obtain an infrared antireflection film having superior antireflection performance to light in the infrared region. SOLUTION: The median wavelength of a wavelength region used is represented by a designed dominant wavelength λ0. In the case of 2 μm<λ0<15 μm, a material of a 1st region with 1.2<=n1<2.0 (n1 is refractive index to λ0), a material of a 2nd region with 2.0<=n1<3.0 and a material of a 3rd region with 3.0<=n1<5.0 are used. A 1st layer on a substrate is formed using the material of the 1st region, the material of the 3rd region and the material of the 2nd region are alternately laminated on the 1st layer and then the material of the 1st layer is laminated as the top layer on the last layer of the material of the 2nd region. The 1st layer preferably comprises Y2O3 or YF3. |
