Optical Pickup Apparatus and Optical Disc Apparatus Including the Same

An optical pickup apparatus comprising at least:

• a diffraction grating configured to split first wavelength light into at least a first main beam and first sub-beam, and to split second wavelength light into at least a second main beam and second sub-beam, the diffraction grating including a diffraction surface portion corresponding to the second wavelength light;
• and
• a photodetector including a first main light-receiving unit configured to be applied with the first main beam, a first sub-light-receiving unit configured to be applied with the first sub-beam, a second main light-receiving unit configured to be applied with the second main beam, and a second sub-light-receiving unit configured to be applied with the second sub-beam,
• a split light ratio among the first sub-light-receiving unit on a front side, the first main light-receiving unit at a center, and the first sub-light-receiving unit on aback side being changed relative to a standardized split light ratio among the first sub-light-receiving unit on a front side, first main light-receiving unit at a center, and first sub-light-receiving unit on a back side, when the repositioned first sub-light-receiving units are disposed in a pairwise manner across the first main light-receiving unit as a center, and the first sub-light-receiving unit on the front side, first main light-receiving unit at the center, and first sub-light-receiving unit on the back side are provided side by side.

An optical pickup apparatus comprising at least:

• a diffraction grating configured to split first wavelength light into at least a first main beam and first sub-beam, and to split second wavelength light into at least a second main beam and second sub-beam, the diffraction grating including a diffraction surface portion corresponding to the second wavelength light;
• and
• a photodetector including a first main light-receiving unit configured to be applied with the first main beam, a first sub-light-receiving unit configured to be applied with the first sub-beam, a second main light-receiving unit configured to be applied with the second main beam, and a second sub-light-receiving unit configured to be applied with the second sub-beam,
• a value of light-receiving sensitivity in the first main light-receiving unit being changed relative to or being equal to a value of standardized light-receiving sensitivity in the first main light-receiving unit,
• a value of light-receiving sensitivity in the first sub-light-receiving unit being changed relative to a value of standardized light-receiving sensitivity in the first sub-light-receiving unit.

An optical pickup apparatus comprising:

• a laser unit including a first light source and second light source disposed on the same surface, the first light source configured to emit a first laser beam, the second light source configured to emit a second laser beam having a wavelength shorter than a wavelength of the first laser beam;
• a diffraction grating including a grating spacing corresponding to the wavelength of the second laser beam, the diffraction grating configured to diffract the first laser beam or second laser beam to generate a main beam and two sub-beams;
• a light converging optical system configured to converge the main beam and two sub-beams to apply a main spot corresponding to the main beam and two sub-spots corresponding to the two sub-beams in such a manner that the main spot and two sub-spots are arranged substantially in a line on a track of an optical disc;
• and
• a photodetector including
• a first main light-receiving unit and two first sub-light-receiving units, the first main light-receiving unit being applied with a reflected spot corresponding to the main spot reflected from the optical disc, and the two first sub-light-receiving units being applied with reflected spots corresponding respectively to the two sub-spots reflected from the optical disc, after the main spot and two sub-spots corresponding to the first laser beam are applied to the optical disc, and
• a second main light-receiving unit and second sub-light-receiving units, the second main light-receiving unit being applied with a reflected spot corresponding to the main spot reflected from the optical disc, and the second sub-light-receiving units being applied with two reflected spots corresponding respectively to the two sub-spots reflected from the optical disc, after the main spot and two sub-spots corresponding to the second laser beam are applied to the optical disc,
• a distance between the first main light-receiving unit and first sub-light-receiving unit and a distance between the second main light-receiving unit and second sub-light-receiving unit being set based on a distance between
• a first irradiation point of the main spot corresponding to a first light-emitting point, which irradiation point is indicative of a position of the first or second light source on a surface of the laser unit facing a surface of the diffraction grating, and
• a second irradiation point of the sub-spot corresponding to a second light-emitting point, which irradiation point is indicative of an apparent position of the first or second light source on the surface of the laser unit, the position being set based on a normal line distance between the first light-emitting point and the surface of the diffraction grating and on a diffraction angle of the diffraction grating.