| 摘要 |
PURPOSE:To reduce the cost of the device by reflecting the light from a stationary optical system toward a disk side, finely moving it in a focusing direction and providing a finely and roughly movable parabolic mirror in the radial direction of the disk. CONSTITUTION:A laser beam changed in direction by a galvanomirror is passed to a parabolic mirror 18 via a afocal lens 16 and a correcting lens 17. The parbolic mirror 18 changes the light path of the laser beam in the direction of a disk recording surface at 90 degrees, and at the same time, stops down the light. At this time, the afocal lens 16 greatly lifts up only the inclination of an optical axis on the parabolic mirror while suppressing the large deviation of the tip of light flux from a head with long light path whose light path was changed by the galvanomirror 15. That is, the spot position of the light can be changed and a tracking operation can be conducted while minimizing the eclipse of the light. Thus, the conventional functions of a lifting prism and an objective lens can be substituted by a single parabolic mirror and the cost of the device can be reduced. |
