Patent ID: 8570845

Claim:
An optical head for reproducing information from an information recording medium having two or more recording layers, the optical head comprising: a light source for emitting a light beam; an objective lens for converging the light beam emitted from the light source to the information recording medium; an astigmatism causing unit for causing an astigmatism in a reflected light beam reflected at the information recording medium; a light beam dividing unit for dividing an incident light beam; and a light detector for detecting the reflected light beam including the astigmatism caused therein by the astigmatism causing unit, wherein the light detector includes: a light-receiving unit for receiving the reflected light beam; a package for covering the light-receiving unit; and a film deposited on a surface of the light detector, wherein the film has a plurality of light guides for guiding the reflected light beam to the light-receiving unit, and a light shield for shielding a region except for a plurality of the light guides from light, wherein the light beam dividing unit divides the incident light beam into a main beam, a first sub-beam, and a second sub-beam, wherein the light-receiving unit includes a main beam light-receiving unit for receiving the main beam, a first sub-beam light-receiving unit for receiving the first sub-beam, and a second sub-beam light-receiving unit for receiving the second sub-beam, wherein the plurality of the light guides are each individually formed on light-receiving surfaces on light beam incident sides of the main beam light-receiving unit, the first sub-beam light-receiving unit, and the second sub-beam light-receiving unit, respectively, and wherein the first sub-beam light-receiving unit and the second sub-beam light-receiving unit are each disposed at a position where an other-layer stray light is not incident.