| 摘要 |
<p>An optical disk device comprises spherical-aberration varying means for varying the spherical aberration at the focal point of a light beam focused by a lens, a second actuator for relatively moving the spherical-aberration varying means finely, and a third actuator for relatively moving the spherical-aberration varying means coarsely. The second actuator moves the spherical-aberration varying means according to the AC component included in the signal from the spherical-aberration sensing means, and the third actuator moves the spherical-aberration varying means according to the DC component included in the signal from the spherical-aberration sensing means. Thus, the optical disk device drives the two actuators according to the signal from the spherical-aberration sensing means so as to reduce the spherical aberration nearly to zero.</p> |
