| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a gas discharge chamber using a calcium fluoride crystal for reducing phenomena of its breakage due to mechanical stress (a window holder and a laser gas pressure) and thermal stress generated by the absorption of the light or the like, and for enhancing linear polarization purity of the output laser while suppressing the deterioration by irradiation of strong ultraviolet laser beam (in particular ArF). <P>SOLUTION: In a first window (2) and a second window (3) of a gas discharge chamber, an incident flat plane and an emitting flat plane are parallel to (111) crystal face of calcium fluoride crystal, the laser beam incident in the calcium fluoride crystal passes through a plane having <111>axis and <001>axis of each of the first window (2) and the second window (3) when viewed from the inside of the chamber (1), and the first window (2) and the second window (3) are installed in a state of being rotated by the same angle around the <111>axis. <P>COPYRIGHT: (C)2013,JPO&INPIT |
