| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical member for vacuum UV region which has low deliquescence and cleavage properties and has high durability even when irradiated with high-energy light, to provide an optical member for vacuum UV region which has high crystal homogeneity free of double refraction and distortion, can be manufactured at a low temperature, is excellent in productivity and contributes to the reduction of the manufacturing cost and to provide a coating martial for the optical member which allows the embodiment of the high durability and the wavelength characteristics specific to thin films. SOLUTION: The optical member for vacuum UV region consisting of the crystal expressed by the formula: KMF3 (where M is respectively independently selected from Ca, Mg, or Sr) and the coating material for the optical member consisting of this fluoride crystal. |
