| 摘要 |
PURPOSE:To align the optical axis of an objective lens and the center of the luminous flux of collimated beams of light with good accuracy by shortening the size in the height direction of the objective lens actuator. CONSTITUTION:This objective lens actuator has a magnetic circuit consisting of a permanent magnet 6 and a magnetic path material 5 in order to move the objective lens 1 in the direction perpendicular to a recording surface and a linear motor which is disposed with a coil 4 in the magnetic gap of the magnetic circuit. The part enclosing the incident luminous flux on the objective lens 1 is constituted to a cylindrical shape around the axial center of the luminous flux. An optical diaphragm 8 of the luminous flux is constituted on the inner peripheral part of the magnetic path material 5 constituted to the cylindrical shape. The diameter of this optical diaphragm is equaled nearly to the diameter of the collimated beams of the light between a light source and the objective lens or the effective diameter of the objective lens. |
