Patent ID: 8184519

Claim:
An optical pickup apparatus comprising: a diffraction grating that a laser beam enters, the diffraction grating being configured to generate a main beam that is 0th order light and sub-beams that are +1st order diffracted light and −1st order diffracted light; an objective lens configured to focus the main beam and the sub-beams onto a signal recording layer; a main-beam light-receiving portion that the main beam reflected by the signal recording layer is applied to; and sub-beam light-receiving portions that the sub-beams reflected by the signal recording layer are respectively applied to, each light-receiving area of the sub-beam light-receiving portions being smaller than a light-receiving area of the main-beam light-receiving portion, wherein a length of the sub-beam light-receiving portions in a direction orthogonal to a tracking control direction is substantially the same as a diameter of a spot having intensity that is 1/e 2 (e is the base of natural logarithms) relative to the maximum intensity of the sub-beams.