| 摘要 |
PROBLEM TO BE SOLVED: To provide a fluorite diffraction optical element improved in workability. SOLUTION: A fluorite (CaF2) substrate having 100 mm (4 inches) diameter and 4 mm thickness is used as a BO(binary optics) substrate 11, on which a fluorine-containing quartz film 12 having 0.17μm thickness is formed in a sputtering type vapor deposition system by using amorphous fluorine-containing quartz (SiO2:F) as the sputtering target and a mixture gas prepare by mixing fluorine by 10% in argon as the sputtering gas. Then the fluorine-containing quartz film 12 is worked with plasma by using chromium masks 21 to 23 and formed into a step-like shape.
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