| 摘要 |
PROBLEM TO BE SOLVED: To suppress deterioration of a window incidental to an increase in an output energy of a laser with a simple structure without complicating a laser chamber. SOLUTION: A face of a window to be installed in a laser chamber is made concave on an inner side of the laser chamber. According to this structure, a light beam incident onto the window from the inner side of the laser chamber changes, at the face on the inner side of the laser chamber, into a divergent light beam, which diverges around an optical axis of the laser as a center, from a parallel light beam, which is parallel to the laser optical axis. As a result, a light beam which reaches the face on an outer side of the chamber has a beam width spread wider than the beam width at the time when the light beam is incident on the face on the inner side of the laser chamber. Consequently, deterioration of the face on an outer side of the chamber is suppressed, because the peak energy density of the laser light beam is lowered at the face on an outer side of the chamber. COPYRIGHT: (C)2009,JPO&INPIT |
