Optical information recording and reproducing apparatus including a total reflection surface or a light shield plate disposed between a polarized light separating surface and a detection device for light beam compensation

摘要

An optical head for an opto-magnetic information recording and reproducing apparatus having stable characteristics. The optical head has a forward path optical system including a polarization beam splitter for reflecting a linearly-polarized light beam in the form of a divergent light beam from a light source, and an objective of a finite imaging system for converging the reflected light beam on an opto-magnetic recording medium, and a backward path optical system in which the reflected light beam from the recording medium is converged by the finite-imaging objective, and in which the converged light beam passes through the polarization beam splitter and is further reflected by a total reflection surface for reflecting this light beam to be led to detection means. A phase difference created in the convergent light beam when the light beam passes through a polarized light separating surface of the polarization beam splitter is compensated for by the total reflection surface.