| 摘要 |
PURPOSE:To prevent the occurrence of strain of a reflecting mirror to stabilize signals by sticking the reflecting mirror to one disc-shaped end of a holding frame and providing projecting parts in the other end of the holding frame and fitting only projecting parts to a movable base and providing a space between said one disc-shaped end and the movable base. CONSTITUTION:A movable base 11 is provided with recessed parts in upper and lower parts so that a holding frame 10 of a reflecting mirror 5 can be held, and projecting parts 10a and 10b of the holding frame 10 are fitted to these recessed parts and are held between inside wall of recessed parts. The movable base 11 and the holding frame 10 are brought into contact with each other only in these holding parts, and a certain space 12 is provided between the disc-shaped parts to which the reflecting mirror 5 is stuck, of the holding frame 10 and the movable base 11. By this constitution, when a horizontal-direction control screw 2 is driven in, only the force which inclines projecting parts 10a and 10b of the holding frame 10 in the horizontal direction is applied, and the movable base 11 is not directly brought into contact with the disc-shaped part. Consequently, the occurrence of strain of the reflecting mirror is prevented to stabilize signals. |
