| 摘要 |
PROBLEM TO BE SOLVED: To provide a light monitoring device in which damage to optical parts is almost prevented and maintainability is improved. SOLUTION: A light monitoring device is provided with a beam splitter 3 to sample a part of the laser light 2 of a narrow-band excimer laser, a light monitor to measure the output characteristics of sample light, and a monitor box 8 to house and approximately shield the light monitor so as to prevent outer air from mixing into the vicinity of the light monitor. In this case, the light monitoring device is provided with a mounting unit 10 with both a flange part 12 provided at the peripheral part on one end side of a hollow tubular cabinet 11 for mounting the beam splitter 3 and a beam splitter mounting surface 16 inclined by a predetermined degreeθwith respect to the axis on the other end side of the tubular cabinet 11, and the no-coat beam splitter 3 is mounted to the beam splitter mounting surface 16. |
