| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an ultraviolet optical system which extends replacement life of a lens having a rotation symmetry axis. <P>SOLUTION: The ultraviolet optical system is constituted of: a first lens 43 which has the rotation symmetry axis CL in the center and whose radii is larger than the diameter of an ultraviolet laser beam; a lens rotating mechanism 53 for rotating the first lens 43; and a controller 60 for controlling the operation of the lens rotating mechanism 53. The ultraviolet laser beam is made incident on a position in a radial direction separated from the rotation symmetry axis CL, the controller 60 rotates the first lens 43 each predetermined time by using the lens rotating mechanism 53, and the ultraviolet laser beam transmits a different circumferential position on the first lens. <P>COPYRIGHT: (C)2010,JPO&INPIT |
