Abstract: An optical pickup can be provided, the optical pickup being capable of recording and playback of a plurality of optical disks having different specs by using light beams of different wavelengths, and further being suitable for integrating the semiconductor lasers and light receiving elements into a single package, by including: first and second semiconductor lasers adjacently disposed; a three-beam diffraction grating for generating three beams for tracking control; a second hologram element for diffracting light of the second semiconductor laser to guide it to a photosensor; a complex polarization beam splitter (PBS) for reflecting only light from the first semiconductor laser; and a first hologram element for diffracting light of the first semiconductor laser to guide it to the photosensor.

Abstract: To read information from a target information recording surface reliably by canceling DC offsets in tracking-signal detection signals is provided. In effecting tracking servo by 3-beam method, auxiliary light receiving domains D3—1, D3—2, D8—1, D8—2 are provided. The auxiliary light receiving domain receives images formed by the light returned from a different information recording surface from the one targeted for reading. Sub beams of ± first-order diffracted light enter the light receiving domains D3, D8, D1, D10. With respect to the diffraction direction of the hologram, the auxiliary light receiving domains D3—1, D3—2 (D8?1, D8—2) are provided on both sides of the light receiving domain D3 (D8). Since signals are computed as: D8-(D8—1+D8—2); and D3-(D3—1+D3—2) with the internal connection, DC offsets can be canceled in RES signals (D1+D3, D8+D10) used in the DPP method.

Abstract: An optical pickup can be provided, the optical pickup being capable of recording and playback of a plurality of optical disks having different specs by using light beams of different wavelengths, and further being suitable for integrating the semiconductor lasers and light receiving elements into a single package, by including: first and second semiconductor lasers adjacently disposed; a three-beam diffraction grating for generating three beams for tracking control; a second hologram element for diffracting light of the second semiconductor laser to guide it to a photosensor; a complex polarization beam splitter (PBS) for reflecting only light from the first semiconductor laser; and a first hologram element for diffracting light of the first semiconductor laser to guide it to the photosensor.

Abstract: Regional borderlines that are the borderlines between the first region and the second region on a diffraction grating of an optical pickup partially overlap a group of y-axis parallel borderlines that are borderlines between pattern A and pattern B that are parallel to a direction parallel to the y-axis.

Abstract: The object of the invention is to accurately detect the amount of tilt in the light reflector to the optical axis of an output light with a simple configuration. A tilt sensing apparatus includes a light reflector, a light source, a condensing unit for condensing an output light from the light source onto the light reflector, and a light sensing unit for sensing the reflected light from the light reflector. An optical device provided in the condensing unit for varying the light quantity of the transmitting light has first and second optical device strips that are formed at the positions of axial symmetry about the optical axis and have a predetermined shift in the direction of a straight line of connecting the axis of the light reflector to the condensed position where the light emitted from the light source is condensed onto the light reflector by the condensing unit.

Abstract: A light branching element which branches a light beam emitted from a light source and reflected on a magneto-optical recording medium is provided with four light branching portions, and three phase compensating means which give a fixed phase &dgr;M to a light beam branched by an M-th (M=2 to 4) light branching portion is disposed on paths of light beams branched by the three light branching portions except the first light branching portion of the four light branching portions. In this optical pickup, servo signals of four kinds of optical recording mediums are respectively detected using light beams detected by three or less groups of light receiving portions selected from among four groups of light receiving portions.

Abstract: A pickup for a magneto-optical recording medium is provided, which improves quality of reproduced signals by eliminating a phase difference between the polarizations and is capable of coping with magneto-optical recording media of different recording/reproducing systems. A return light beam of light reflected by a magneto-optical recording medium is polarized and separated into ± first-order diffracted lights through a light-branching diffraction element provided between a light source and an objective lens. The ± first-order diffracted lights are compensated for their phases through first and second phase compensation elements so that there is no phase difference between the polarizations, and are, further, polarized and separated through the first and second polarization/separation elements, and are received by first and second light detectors.

Abstract: An object of the present invention is to attain stable tracking servo performance by suppressing an offset caused by a shift of an object lens or a tilt of a disk, despite the one-beam method which does not cause reduction in light quantity of the main beam. A diffraction grating is provided between a hologram and a light receiving section, and a diffraction efficiency of the diffraction grating is varied in a grating longitudinal direction. For example, if an incident light beam on the diffraction grating is shifted in the grating longitudinal direction, the quantity of received light in each light receiving section varies to cause offset. By performing tracking servo so as to cancel the change, it is possible to correct the offset, thereby attaining stable tracking servo performance.

Abstract: First, second semiconductor lasers and a photodetector are integrated in a laser package of an integrated laser unit. A composite PBS is so structured that generally 100% of s-polarized light derived from the first semiconductor laser is reflected while generally 100% of s-polarized light derived from the second semiconductor laser is transmitted. Then, return beams of s-polarized light of the first, second semiconductor lasers separated by the composite PBS 18 are converged on the same photodetector by the first, second polarization hologram devices. By doing so, the first, second polarization hologram devices are adjusted independently of each other, so that the offset adjustment of servo error signals for the first, second semiconductor lasers can be easily achieved in assembly process. Thus, the optical pickup becomes easy to assemble and adjust.

Abstract: A diffraction grating for generating a plurality of beams includes a plurality of gratings. The plurality of gratings are formed to have an axis of symmetry perpendicular to the direction in which a beam is divided on a surface of diffraction grating and include at least two gratings having different fundamental cycles. The plurality of gratings are formed such that they have an axis of symmetry perpendicular to the direction in which a beam is divided on a surface of the diffraction grating, for generating a plurality of beams. The fundamental cycle increases as a function of the distance from the axis of symmetry, and therefore aberration in the periphery of scattering light may be reduced.

Abstract: An optical pickup device comprises a semiconductor laser, an optical system which converges light projected by the semiconductor laser onto an optical disk and directs reflected light from the optical disk to a photoreceptor element, and a photoreceptor element which detects the reflected light; the photoreceptor element including at least two main photoreceptive domains divided from one another by a dividing line, which receive reflected light corresponding to a focusing error of the light projected onto the optical disk, and at least one auxiliary photoreceptive domain which detects reflected light which exceeds the main photoreceptive domains in a defocused state; in which the auxiliary photoreceptive domain is provided adjacent to an end of said main photoreceptive domains in the direction of the dividing line.

Abstract: An optical pickup can be provided, the optical pickup being capable of recording and playback of a plurality of optical disks having different specs by using light beams of different wavelengths, and further being suitable for integrating the semiconductor lasers and light receiving elements into a single package, by including: first and second semiconductor lasers adjacently disposed; a three-beam diffraction grating for generating three beams for tracking control; a second hologram element for diffracting light of the second semiconductor laser to guide it to a photosensor; a complex polarization beam splitter (PBS) for reflecting only light from the first semiconductor laser; and a first hologram element for diffracting light of the first semiconductor laser to guide it to the photosensor.

Abstract: Light from a semiconductor laser is converged by an objective lens onto an optical disk, and return light thereof is directed to a light receiving element by a three-division hologram element. The light receiving element includes a two-division main light receiving region for detecting a focus error signal and sub light receiving regions respectively provided on both sides of the main light receiving region for compensating the focus error signal. Based on output signals of the above main and sub light receiving regions, a focus error signal is detected. Note that it is arranged that the sub light receiving regions receive the return light from the optical disk and hence output signals only when the objective lens defocuses being positioned outside a dynamic range. Therefore, with the use of outputs of the sub light receiving regions, the focus error signal is quickly converged to 0, when the objective lens is positioned outside the dynamic range.

Abstract: An optical recording and reproducing apparatus records two rows of a plurality of pit patterns with respect to one track by modulating two light beams and by converging the modulated two light beams in parallel onto the track. The plurality of pit patterns are detected and judged by a multiple hologram on which reflected object waves of all kinds of pit patterns are recorded, thereby enabling to carry out recording of information. With the arrangement, since multiple values recording and reproducing can be carried out with respect to a magneto-optical disk, the recording capacity becomes greater than the conventional case and the reproduced signal having little crosstalk can be obtained according to the present way of reproducing.

Abstract: An optical pickup apparatus including a light emitting source, a hologram element for scanning a recording medium with light beams emitted from the light emitting source, a hologram lens for focusing the light beams introduced from the hologram element on the recording medium, an optical detector for detecting the light beams reflected from the recording medium, and a first optical system for directing the light beams reflected from the recording medium to the optical detector. The hologram element includes an optical diffraction grating for diffracting the light beams emitted from the light emitting source and a control means for controlling the rotation of the hologram element in a swinging manner. The hologram element can have hologram gratings on both surfaces thereof; one of them has a pattern of straight lines and the other has a pattern of concentric circles to obtain a widened deflection angle.

Abstract: An inclination adjusting device for an objective lens used for an optical information recording and reproduction apparatus with a reduced number of components for a small size and light weight is provided. An objective lens is held at an end portion of a plate spring. The other end portion of the plate spring is fixed to an adjusting board, which is supported in a manner so that it can tilt against a base on a spherical element as a support. The adjusting board is properly positioned with regard to the base by use of one guide pin. The adjusting board is tilted in the longitudinal direction of the plate spring and in the direction crossing the longitudinal direction by use of a first and second adjusting screws, respectively.

Abstract: An optical head, for an optical disk recording/reproducing apparatus, for irradiating a recording medium by a light beam emitted from a light source and introducing an information light formed by a light beam reflected from the recording medium to a photo detector, a shift of an optical axis of the information light being minimized. The optical head includes a unit for receiving the information light which is reflected from the recording medium, a first reflecting unit for reflecting such information light, a second reflecting unit for reflecting the information light reflected by the first reflecting unit and for directing the reflected information light toward the photo detecting system, and a unit for emerging the information light reflected by the second reflecting unit to the photo detecting system.