| 摘要 |
PURPOSE:To control a servo without the effect of a disturbance by condensing the external beams of a light flux to the center area of a photo converter, condensing the internal beams to the external area, and generating a servo signal based on a light receiving output in the external area. CONSTITUTION:The reflected beams from a recording disk 4 is converged by an objective lens 3, and the convergent light flux is made incident through a beam splitter 2 on a compound lens 7. The external beams of the light flux being made incident on the compound lens 7 are condensed on a center area 8c of a five-divided photo detector 8, and the internal beams of the light flux are respectively condensed on external areas 8a, 8b, 8d and 8e. Further the servo signal is generated based on the light receiving outputs of the external areas 8a, 8b, 8c and 8d. Thus the servo can be controlled without the effect of the disturbance. |
