Sanyo Electric Co., Ltd.

Kiyotaka Eizumi

Minoru Sato

Tohru Hotta

Shuichi Ichiura

Chiaki Asakawa

Noriyoshi Ooyama

Yoshio Hayashi

An optical pickup apparatus includes at least: a light emitting element capable of emitting at least first wavelength light and second wavelength light; and a diffraction grating configured to split the first wavelength light into at least a first main beam and a first sub-beam and to split the second wavelength light into at least a second main beam and a second sub-beam, a following expression (1) being satisfied: where: Ypis an interval between the first main beam and the first sub-beam when a first media corresponding to the first wavelength light is irradiated with the first main beam and the first sub-beam, and Ypis an interval between the second main beam and the second sub-beam when a second media corresponding to the second wavelength light is irradiated with the second main beam and the second sub-beam.

Optical pickup apparatus and disc apparatus including the same

An optical pickup apparatus comprising: a laser light source configured to emit a laser beam; an objective lens configured to apply the laser beam to an optical recording medium; and a beam splitter including a first reflective film configured to reflect the laser beam so as to be directed to the objective lens, the beam splitter interposed in an optical path between the laser light source and the objective lens, an incidence polarization angle of the laser beam relative to the first reflective film being set such that a P-polarization component is greater than an S-polarization component in linear polarization components of the laser beam incident on the first reflective film.

Optical pickup apparatus

An optical-pickup apparatus comprising: a laser-light source including first-and-second-light-emitting points for laser lights with first-and-second wavelengths which points are disposed at positions deviating in a direction optically corresponding to an optical-disc-tracking direction; a diffraction grating including a plurality of periodic structures which are joined to be different in phase from each other in the direction and each of which includes a recess and projection repeated in a direction optically corresponding to an optical-disc-tangential direction, the diffraction grating being configured to generate main-and-sub-luminous fluxes from the laser light; a holder to hold the diffraction grating to be movable in the direction corresponding to the tracking direction; a collimating lens; an objective lens to focus the main-and-sub-luminous fluxes from the collimating lens on the same track of an optical disc; and a photodetector to be applied with reflected lights of the main-and-sub-luminous fluxes from the optical disc, to generate main-and-sub-push-pull signals.

An optical-pickup apparatus comprising: a laser-light source; a diffraction grating including first-and-second regions of periodic structures different in phase from each other and a third region whose periodic structure is different in phase from the first-and-second regions; an objective lens focusing main-and-sub-luminous fluxes generated by the diffraction grating on the same optical-disc track; and a photodetector to receive reflected light of the main-and-sub-luminous fluxes from an optical disc and output a detection signal for generating main-and-sub-push-pull signals, a relationship between an incident light width in the objective lens corresponding to the third region and pupil diameters of the objective lens corresponding to first-and-second wavelengths of laser lights being adjusted so that a ratio of minimum value to maximum value of a differential-push-pull-signal is at substantially 50% or more and a ratio of sub-push-pull-signal level to main-push-pull-signal level is at substantially 15% or more, in both cases of the laser lights.

An optical pickup apparatus comprising: a diffraction grating including a first grating for diffracting a first laser light beam, and a second grating for diffracting a second laser light beam which is shorter in wavelength than the first laser light beam, the diffraction grating being disposed in a common optical path for guiding the first laser light beam and the second laser light beam to an optical disc; and a photo detector including in a first light receiving area, a main light receiving unit, a front sub-light receiving unit, and a rear sub-light receiving unit that receive reflected light beams, which are reflected by the optical disc, of a main beam, of a front sub-beam, and of a rear sub-beam, respectively, the first laser light beam being diffracted by the diffraction grating into the main beam, the front sub-beam formed in front of the main beam, and the rear sub-beam formed at the back of the main beam, wherein the first grating is set such that the front sub-light receiving unit and the rear sub-light receiving unit in the first light receiving area are disposed at positions which substantially avoid unnecessary diffracted light beam spots which are generated by projecting to the first light receiving area unnecessary diffracted light beams, the unnecessary diffracted light beams generated by the second grating from the first laser light beam.

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Oizumi-machi, Japan

Kiyotaka Eizumi