MAGNETO-OPTICAL RECORDING/REPRODUCING APPARATUS WITH OPTICALPICKUP DEVICE HAVING A MULTI-LAYER DIELECTRIC FILM BEAM SPLITTER

摘要

An optical pickup device for an information recording and/or reproducing apparatus in which fluctuations in polarization film characteristics due to the variable incident angles of the light beam to the beam splitter may be reduced to prevent C/N characteristics from being lowered. The optical pickup device includes an objective lens 3 for converging a light beam L from a laser light source 1 to a magneto-optical disc 2, a beam splitter 8 arranged on a light path between the laser light source 1 and the objective lens 3 for guiding a return laser light beam Lr from the disc to outside of the light path, and a photodetector_4 for detecting the return light beam Lr guided by the beam splitter 8 to outside of the light path. The beam splitter 8 is arranged at a portion in the light path between the laser light source 1 and the objective lens 3 in which the light beam L from the laser light source 1 is in a state of a divergent light beam. The multi-layered dielectric film 12 of the beam splitter 8 is of polarization film characteristics of deflecting 65% of S-polarized light components and 35% of the P-polarized light components of the light beam L and the return light beam Lr incident on the multi-layered dielectric film 12.