| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical apparatus configured such that an increase in transmission loss and the optical distortion of silica glass are prevented by minimizing defects in the silica glass even when high energy light such as ultraviolet light is emitted over a long period. SOLUTION: The optical apparatus 1 has an optical element (3a, 3b, 3c and 3d) of quartz accommodated in a container 2 which is filled with pure hydrogen or gas containing hydrogen. The optical element (3a, 3b, 3c and 3d) is preferably subjected to heat treatment in a hydrogen atmosphere of 1 to 500 kgf/cm<SP>2</SP>in hydrogen pressure and 80 to 500°C in temperature before being accommodated in the container 2. Here, the hydrogen concentration of the gas containing hydrogen is preferably set to be less than 4% by volume. COPYRIGHT: (C)2004,JPO
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