| 摘要 |
PURPOSE:To obtain reflection preventing film having high light resistance usable also for CO2 laser by forming lead fluoride film on chalcogens glass film having a specified refractive index, and forming zinc sulphide film or selen sulphide film on the chalcogens glass film. CONSTITUTION:A material having high refractive index i.e. chalcogens glass 2 which is in amorphous state and having low absorptance, good adhesion and >=2.6 refractive index, is first vapor-deposited on a KRS-5 substrate 1 having 2.37 refractive index with extremely precisely polished surface suitable to optical purpose. Then, PbF2 3 of low refractive index as low as ca. 1.6 and low absorptance is vapor-deposited. Thereafter, a high refractive material 4 i.e. ZnS of 2.2 refractive index or ZnSe of 2.4 refractive index is vapor-deposited thereon in order to protect the chalcogens glass PbF2 of low resistance to environment from the influence of the environment. By this method, a reflection preventing film comprising three-layered structure having low absorptance, high light resistance, and high resistance to environment, is provided. |
