| 摘要 |
PURPOSE:To facilitate assembly and regulation by equipping a means to branch optical beams into mutually approximately parallel first and second optical beams and a means to regulate the position of a convergent means for a recording medium and to respond to the first and second optical beams. CONSTITUTION:First and second optical refraction bodies 18 and 19 branch the optical beams into parallel first and second optical beams L1 and L2 by the boundasy of an optical axis arranged on the light path of the incident optical beams. Next, the optical beams L1 and L2 which irradiates a photo detector 20 are converted into electric signals in respective photo detecting areas, and processed. In the processing, a focusing error signal is generated from a driving circuit 44, a current is supplied to a voice coil 8, an objective lens 16 is driven in a light axis direction, and the focus of the optical beams is controlled. Further, a tracking error signal is generated from a driving circuit 45, the current is supplied to the voice coil motor 8, an optical head 3 is moved in the surface orthogonal to the light axis of the objective lens 16, and a prescribed track is traced by the optical beams. Thus, the assembly and regulation can be facilitated. |
