| 摘要 |
PURPOSE:To increase the speed of a seek operation by freely variably providing a fixed side deflection member in a direction to vary a deflection angle for a movable side deflection member and varying the fixed side deflection member according to a tracking error signal by a detection optical system. CONSTITUTION:A deflecting mirror 41 as the fixed side deflection member is provided freely rotatably and displaceably around a supporting point 43 on a supporting member 42 for a fixed optical system 7, and the fixed optical system 7 changes the deflection angle for a deflecting prism 16 in a movable optical system 6 by rotating and displacing the deflecting mirror 41. This deflecting mirror 41 is rotated and displaced by a drive motor 44 to be drive- controlled by a control means according to the tracking error signal from a detection optical system 17 provided in the fixed optical system 7. Consequently, tracking by the displacement of an objective lens 3 itself becomes unnecessary, and it becomes unnecessary to mount a tracking servo mechanism in the movable optical system 6. Thus, the movable optical system can be lightened, and the high-speed seek operation can be attained. |
