| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared optical film having enhanced heat resistance without greatly degrading optical performance.SOLUTION: An infrared optical film, formed to cover an optical reflection film formed on a substrate, comprises: a first multilayer group having a layered configuration in which first high refractive layers formed of ZnS or ZnSe and first low refractive layers formed of a fluoride material lower in refractive index than a material of these first high reflective layers are alternately arranged; and a second multilayer group located closer to the optical reflection film relative to this first multilayer group, and having a layered configuration in which second high refractive layers formed of Ge and second low refractive layers formed of ZnS or ZnSe are alternately arranged so that layers in contact with the optical reflection film are the second low refractive layers and those in contact with the first multilayer group are the second high refractive layers. The first multilayer group is formed such that the first low refractive layers are layers in contact with the second multilayer group. |
