SCANNER

摘要

PROBLEM TO BE SOLVED: To provide a scanner in which the positioning time of a mirror is shortened and the positioning accuracy of a laser beam is improved. SOLUTION: In addition to an angle sensor 9, distortion sensors 10 to 13 for detecting the twist angle of a rotary shaft 3 are arranged at the predetermined positions of the rotary shaft 3. A state quantity detecting means 40 to estimate the state quantity of the rotary shaft 3 is provided in a servo control system. The state quantity of the rotary shaft 3 is estimated by using the measured value of the angle sensor 9 and the measured values of the distortion sensors 10 to 13. A torsional vibration generated at the rotary shaft 3 is suppressed to position the mirror 2 by feeding back the estimated value.