Optical system for compensating for coma aberration and/or spherical aberration in an optical pickup device and optical pickup device having the same

摘要

An optical system for optical pickup, which optical system is used for performing recording, reproducing, and/or erasing of information on an optical recording medium and has a simple configuration, is provided. An optical pickup device 1 includes a collimator lens system 23, a beam expander 33, and an objective lens system 34 that includes an S-SIL element 27b. The beam expander 33 includes a lens element 33c that is supported so as to be movable in a direction perpendicular to an optical axis. By moving the lens element 33c in the direction perpendicular to the optical axis, a coma aberration of a spot on a recording layer can be compensated in a state where the interval between a surface of an optical recording medium 28 and the S-SIL element 27b opposed thereto is maintained constant.