OPTICAL PICKUP, OPTICAL INFORMATION RECORDER AND OBJECTIVE LENS

摘要

PROBLEM TO BE SOLVED: To record and reproduce plural optical disks having different thickness of the protecting layer by a common lens. SOLUTION: This pickup is constituted in such a manner that the light is converged on the information recording surface of the optical disk by the objective lens 3 and the reproduction is made by the irradiation of this reflected light on a light receiving element through the objective lens 3. In this case, by the objective lens 3 subjected to aberration correction in accordance with the thickness of protecting layer of the optical disk 4 for digital video disk, the distance in between the object is shortened when the thickness of the protecting layer is increased, so that the aberration of the optical disk 5 for compact disk becomes best.