Abstract: 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

Abstract: 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

Abstract: A yoke constituting a magnetic actuator for driving an objective lens has a plurality of arms arranged in a plane intersecting the optical axis of the lens perpendicular thereto. An optical system including the objective lens is disposed at one side of the yoke and has the outer peripheral portion of the lens positioned partly in the space between adjacent two arms. The lateral width of the device is decreased by an amount corresponding to the lap of the lens over the yoke. A cover plate is secured to the upper surface of the magnetic actuator in intimate contact with the upper end faces of the yoke arms to give enhanced rigidity to the device.

Abstract: An optical pickup device in which a laser light source is so disposed that one of two dividing lines of a photo-detector having at least four sensing portions symmetrically divided by the dividing lines so as to detect focusing deviation of a light beam onto a signal surface of a record disc, is aligned with the tangential direction of the signal track at the portion where the light beam is projected onto the signal surface, whereby the optical pickup is free from a wrong focusing control due to erroneous detection even during track jumping.