| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas laser device which can obtain a laser beam with the beam quality suitable for exposure by reducing an influence of acoustic waves. SOLUTION: The gas laser device comprises a gas temperature detecting unit (42) for detecting gas temperature (T), a laser controller (29) for detecting the oscillation frequency (f), monitors (45, 46) for measuring beam quality, and a gas temperature changing means (43) for changing gas temperature (T) of the laser gas. The gas laser controller (29) sets, based on the gas temperature (T), non-allowable frequency (f1n) in which the beam quality of laser is not in the allowable range, changes the gas temperature (T) of laser gas when the oscillation frequency (f) is almost matched with the non-allowable frequency (f1n), and shifts the non-allowable frequency (fmn) at the gas temperature (T) from the oscillation frequency (f) of the laser beam. COPYRIGHT: (C)2005,JPO&NCIPI |
