OBJECTIVE LENS FOR OPTICAL HEAD, OPTICAL HEAD USING THE SAME, AND OPTICAL DISK DEVICE

摘要

PROBLEM TO BE SOLVED: To suppress the occurrence of an aberrations even when an objective lens is commonly used for two wavelengths by utilizing a module in which two semiconductor lasers are built in one package.

SOLUTION: The objective lens 20 is so set that the comatic aberration for a first optical disk D1 has a code reverse to the code for a second optical disk by generating an astigmatism axially corresponding to a wavefront aberration ≥0.01λ [rms] when receiving the laser light from the laser 11a onto the first optical disk. The first and second semiconductor lasers 11a and 11b are so arranged as to be arrayed along the direction of a focal line F1 near the objective lens 20 formed by the direct incident luminous flux on the objective lens 20 parallel with the optical axis. The optical axis of the objective lens and the normal of the optical disk incline relatively to each other, thereby, the comatic aberrations for both the optical devices are corrected.

COPYRIGHT: (C)2004,JPO