| 摘要 |
PURPOSE:To prevent increase in surface roughness and decrease in linear transmittance for light by coating at least one surface of a base body with a coating material having lower solubility to water and higher hardness compared to the base body. CONSTITUTION:This optical member consists of a base body and a coating material. The base body consists of polycrystalline barium fluoride sintered body and the coating material is applied at least one surface of the base body. This coating material consists of such a material having lower solubility with water and higher hardness compared to the base body. In this case, it is preferable that the coating material consists of either magnesium fluoride or calcium fluoride. More preferably, the coating material has 0.1-10mum thickness. This optical thin film is formed by usual vacuum vapor deposition or sputtering method, and can be made dense with stable refractive index. |
