| 摘要 |
PROBLEM TO BE SOLVED: To provide a silica glass optical material which has high initial transmitivity to vacuum ultraviolet ray of 155 to 195 nm wavelength and is excellent in high precision, high durability and homogeneity and to provide its manufacturing method and a projection lens. SOLUTION: The silica glass optical material of this invention is the silica glass optical material for the projection lens used in vacuum ultraviolet ray lithography of 155 to 195 nm wavelength and is distinguished by having ultrahigh purity, containing 1 to 10 wt.ppm OH group, 100 to 10,000 wt.ppm F, 1×1017 to 1×1019 molecule/cm2 of H2 and having F concentration distribution of axial symmetry about a central axis.
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