Optical head system and its optical disc

摘要

An optical head system designed to accomplish an information recording and/or reproduction from opposite disc surfaces of an optical disc with the use of a single light source. The optical head system comprises a source of light for providing a linearly polarized beam of light; a collimator lens for collimating the linearly polarized beam of light into a collimated beam of light; a polarizing direction rotating unit for arbitrarily varying a direction of linear polarization of said beam of light; a polarizing beam splitter for dividing the beam, whose direction of linear polarization has been varied, into first and second beam components; and objective lenses for focusing the first and second beam components into respective penciles of light which are projected onto first and second, opposite disc surfaces of an optical disc or one disc surfaces of respective first and second optical discs.