Patent ID: 7664005

Claim:
An optical pickup apparatus, comprising: a laser light source; a condensing optical system for dividing laser light from the laser light source into a main beam and a sub beam, and condensing the main beam and the sub beam at a recording layer on a multilayer optical information storage medium; and a detection optical system for detecting reflected light reflected by the recording layer on the multilayer optical information storage medium, wherein the detection optical system comprises: an optical system for narrowing the reflected light from the recording layer; a reflecting plate having reflecting regions which are independently disposed at spot positions of the main beam and the sub beam narrowed by the optical system; an astigmatic aberration-containing condensing element; and a photodetector having a detector element for detecting the main beam and another detecting element for detecting the sub beam, wherein the reflected light reflected by the reflecting plate is condensed by the astigmatic aberration-containing condensing element on the photodetector where it is detected.