Optical pick-up, optical data recording apparatus and objective lens for optical data recording material

摘要

An optical pick-up for reading data in the data recording surface of an optical data recording material by collecting light from a light source by means of an objective lens, and shining reflection light from the data recording surface onto a light receiving element through the objective lens, the optical pick-up being adapted to read data in the data recording surface of first and second optical data recording materials wherein the thickness of a protective substrate is different from each other, wherein the objective lens is so determined that the aberration is corrected in response to the thickness of the protective substrate of the first optical data recording material, and in reading data in the data recording surface of the second optical data recording material which has a thickness different from that of the first optical data recording material, the object.image distance is adjustable so as to adjust the aberration.