Patent ID: 6885616

Claim:
An optical pickup apparatus comprising: a light source which emits a light beam which is linearly-polarized; a collimator lens which collimates the light beam emitted from said light source into a parallel light beam; a phase device which changes the polarization of an inner light and the polarization of an outer light so that the inner light and the outer light are circularly polarized and the rotating direction of the inner light polarization is opposite to the rotating direction of the outer light polarization, the inner and outer lights being inner and outer radius portions of said parallel light beam, respectively; an objective lens which converges the light beam passed through said phase device so that a converge light beam is incident on an information recording medium; and a detector which detects the respective intensities of reflected lights of the inner and the outer lights from said information recording medium to generate error information with regard to said information recording medium.