| 摘要 |
PROBLEM TO BE SOLVED: To prevent defocusing because of a thickness variation of a medium protecting layer by setting an actuator for driving an objective lens in a focus direction to keep up with face oscillation and inclination of a medium surface and avoid a focus shift. SOLUTION: The optical head is pressed by an elastic member 34, having a damper member 32 sliding in touch with a medium 31. A hardness, a length and a thickness of the elastic member and, a hardness, a thickness and an area of the damper member are set so that an objective lens 37 does not hit the medium 31 when an upper face of an actuator-moving part 38 hits a damper member mount member 33. At a focusing operation, for example, the focusing is carried out based on a face of the damper member mount member 33 which regulates the operation of the objective lens 37 as a reference position. Since the medium relatively moves while being kept in touch with the optical head by the damper member, the optical head operates tracing a shape of a medium surface. |
