| 摘要 |
PROBLEM TO BE SOLVED: To efficiently adjust plane tilt by adjusting a phase with respect to the flanges of the respective reflection surfaces of a rotary mirror. SOLUTION: Phase detection sensors 35 and 36 are arranged at the upper part of the rotary mirror and inside the circumscribing surface. Besides, the sensors 35 and 36 are turned on when the rotary mirror 1 having two deflection surfaces 1a and 1b is positioned downward and installed by being provided with such positional relation that they can be surely simultaneously turned on when the mirror 1 is rotated. As the mirror 1 is rotated, the sensors 35 and 36 are successively repeatedly turned on and off. Thus, the positions of the deflection surfaces 1a and 1b are discriminated. |
