| 摘要 |
PURPOSE:To enlarge the change of angle of luminous flux due to an optical deflector or a movable mirror, etc., and to expand the moving range of the detection spot of an optical disk, and to sufficiently execute tracking correction, etc., by forming the optical plane of a prism at an outgoing side so as to be inclined. CONSTITUTION:The junction plane of the prisms 11 and 12 is made 13, and the plane of the prism 12 at the outgoing side is made the optical plane 13, and the optical plane 13 is formed so as to be inclined against an incident optical axis K1 to this plane. The optical axis K1 incident upon this plane 13 at an angle theta1 is refracted, and the outgoing angle of an outgoing optical axis K2 becomes theta2. An objective lens 5 and the optical disk D are arranged on this refracted optical axis K2. Then, when the angle of the optical axis is changed by DELTAtheta1 by the optical deflector or the movable mirror, the angle DELTAtheta2 of the outgoing optical axis from the plane 13 is enlarged by a multiplying factor M (M>1). Thus, the movement quantity of the detection spot formed on the recording surface of the optical disk D can be expanded. |
