Patent ID: 8750083

Claim:
An optical pickup apparatus comprising at least: a diffraction grating configured to split first wavelength light into at least a first main beam and a first sub-beam, and to split second wavelength light into at least a second main beam and a second sub-beam, the diffraction grating including a diffraction surface portion corresponding to the second wavelength light; a photodetector including a first main light-receiving portion configured to be irradiated with the first main beam, a first sub-light-receiving portion configured to be irradiated with the first sub-beam, a second main light-receiving portion configured to be irradiated with the second main beam, and a second sub-light-receiving portion configured to be irradiated with the second sub-beam, a value of a signal outputted from the first main light-receiving portion being changed relative to or being equal to a value of a standardized signal outputted from the first main light-receiving portion, a value of a signal outputted from the first sub-light-receiving portion is changed relative to a value of a standardized signal outputted from the first sub-light-receiving portion; and an operation unit coupled to receive the signal outputted from the first main light-receiving portion and the signal outputted from the first sub-light-receiving portion, the operation unit configured to compensate for the difference between the value of the signal outputted from the first sub-light-receiving portion and the value of the standardized signal outputted from the first sub-light-receiving portion.