OPTICAL MEMBER FOR VACUUM ULTRAVIOLET REGION COMPRISING FLUORIDE CRYSTAL AND COATING MATERIAL FOR OPTICAL MEMBER

摘要

PROBLEM TO BE SOLVED: To provide an optical member for the vacuum ultraviolet region having low deliquescent property and low cleavability and also having high durability even when irradiated with high energy light. SOLUTION: The optical member for the vacuum ultraviolet region is formed from a fluoride crystal represented by the formula BaLiF3. A coating material for an optical member can also be formed from this fluoride crystal.