| 摘要 |
PURPOSE:To obtain focus information on the basis of the output of a CCD obtained by focusing reflected light from a disk upon a CCD surface extending in the direction of the optical axis of the reflected light as inclined to the optical axis. CONSTITUTION:Reflected light from a disk is focused by a condenser 9 on a CCD12 and a CCD12' surfaces extending in the direction of the optical axis of the reflected light inclined at a small angle to the optical axis. Focusing positions 13-15 shift according to the distance between the disk and said optical system and the output width 22 of the CCDs varies accordingly. On the basis of the signal, a focus error signal for automatic focusing is generated. In the figure, a 26 is a level for the addressing of light shielding bodies 18 and 18', and a 27 is a level generated by bias light. |
