OBJECTIVE AND OPTICAL HEAD DEVICE

摘要

An objective (1) for optical disks for focusing the beam of light from a lig ht source. The third-order comatic aberration of the objective of when an optic al disk (2) inclines at a unit angle is larger than that of when the objective inclines at a unit angle. The objective is mounted on an actuator that inclines the objective according to the inclination of the optical disk. Therefore the numerical aperture of the objective is large. The manufacture and assembly of the objective are facilitated. The third-order comatic aberration caused when the optical disk inclines because of its warp can be corrected by inclining the objective, thereby decreasing the residual astigmatism after the correction.