Optical disc recording reproducing apparatus recording/reproducing information to/from optical discs according to different standards

摘要

An optical disc reproducing apparatus includes a semiconductor laser, an objective lens converging a laser beam from the semiconductor laser on a recording surface of an optical disc, a polarization plane rotating unit selectively rotating the plane of polarization of the laser beam according to the thickness of a substrate of the optical disc, and a polarizing filter selectively blocking a peripheral portion of the laser beam depending on the plane of polarization. In one embodiment, a numerical aperture changing unit includes a non-patterned twisted nematic liquid crystal, and the polarizing filter includes a polarizing film having a polarization characteristic at its peripheral portion.