Abstract: An optical disk apparatus includes an optical pickup and a disk-rotation driving unit configured to rotationally drive the optical disks. The optical pickup includes a first emission unit configured to emit a first wavelength beam; a second emission unit configured to emit a second wavelength beam; a third emission unit configured to emit a third wavelength beam; an objective lens configured to focus the first to third wavelength beams emitted from the first to third emission units, respectively, at a signal recording surface of an optical disk; a light-path combining unit configured to combine an optical path of the first wavelength beam emitted from the first emission unit and an optical path of the second and third wavelength beams emitted from the second and third emission units, respectively; and an aberration correcting unit provided on the optical path of the second and third wavelength beams.

Abstract: An optical pickup is configured to emit a light beam to an optical disk having a plurality of recording layers and is configured to receive a reflection light beam obtained when the emitted light beam is reflected at a recording layer of the optical disk. The optical pickup includes an objective lens configured to focus the light beam emitted from a light source at a focused recording layer of the optical disk and receive the reflection light beam; a focusing lens configured to focus the reflection light beam received by the objective lens; and a stray-light removing element including the boundary surface and being configured to remove stray light from the reflection light beam by reflecting only the stray light included in the reflection light beam reflected at an unfocused recording layer at the boundary surface.

Abstract: An optical disk apparatus includes an optical pickup and a disk-rotation driving unit configured to rotationally drive the optical disks. The optical pickup includes a first emission unit configured to emit a first wavelength beam; a second emission unit configured to emit a second wavelength beam; a third emission unit configured to emit a third wavelength beam; an objective lens configured to focus the first to third wavelength beams emitted from the first to third emission units, respectively, at a signal recording surface of an optical disk; a light-path combining unit configured to combine an optical path of the first wavelength beam emitted from the first emission unit and an optical path of the second and third wavelength beams emitted from the second and third emission units, respectively; and an aberration correcting unit provided on the optical path of the second and third wavelength beams.

Abstract: A converging optical apparatus reduces the diffraction loss and realizes compatibility with three different wavelengths by means of a hologram element.

Abstract: The present invention is relative to an objective lens (15) for an optical pickup, having a numerical aperture not less than 0.8, and adapted for correcting the chromatic aberration at an image point on an optical axis for light with a wavelength within several nm about a reference wavelength which is not larger than 420 nm. This objective lens is made up by a first lens set GR1, having a compound surface S2 of a refractive surface S2r and a diffractive surface S2d, and a second lens set GR2, having a positive refractive power, looking from the light source side. The compound surface of the first lens set is formed by adding the diffractive surface having the positive refractive power to the refractive surface which is an aspherical surface having the negative refractive power. The lens forming the second lens set is a single lens including at least one aspherical lens.

Abstract: An objective lens unit for an optical pickup used for recording and/or reproducing information signals from an optical disc. The objective lens unit includes a resin layer (21) having, sequentially from an object side, a first surface S1 as an aspherical surface and a second surface S2 as an aspherical surface, at least one of the first surface and the second surface including a diffractive surface, and a lens of glass (22) having the second surface S2 as an aspherical surface and a third surface S3 as an aspherical surface. The lens unit is corrected for the chromatic aberration on an image surface on the optical axis with respect to the light of a reference wavelength not larger than 420 nm within several nm of the reference wavelength, with the numerical aperture of the lens unit being not less than 0.8. This objective lens unit is able to converge the laser light close to the limit of diffraction on the image surface.

Abstract: The present invention is concerned with an objective lens for an optical pickup, which is made up by a single lens of a meniscus structure, and which includes, looking sequentially from a light source side, a first surface S1 formed by an aspherical surface, having a positive refractive power, and a second surface S2, formed by an aspherical surface, having a negative refractive power, with the numerical aperture (NA) of the lens being not less than 0.8.

Abstract: The present invention is relative to an objective lens (15) for an optical pickup, having a numerical aperture not less than 0.8, and adapted for correcting the chromatic aberration at an image point on an optical axis for light with a wavelength within several nm about a reference wavelength which is not larger than 420 nm. This objective lens is made up by a first lens set GR1, having a compound surface S2 of a refractive surface S2r and a diffractive surface S2d, and a second lens set GR2, having a positive refractive power, looking from the light source side. The compound surface of the first lens set is formed by adding the diffractive surface having the positive refractive power to the refractive surface which is an aspherical surface having the negative refractive power. The lens forming the second lens set is a single lens including at least one aspherical lens.

Abstract: The present invention is concerned with an objective lens for an optical pickup, which is made up by a single lens of a meniscus structure, and which includes, looking sequentially from a light source side, a first surface S1 formed by an aspherical surface, having a positive refractive power, and a second surface S2, formed by an aspherical surface, having a negative refractive power, with the numerical aperture (NA) of the lens being not less than 0.8.

Abstract: An objective lens unit for an optical pickup used for recording and/or reproducing information signals fr an optical disc. The objective lens unit includes a resin layer (21) having, sequentially from an object side, a first surface S1 as an aspherical surface and a second surface S2 as an aspherical surface, at least one of the first surface and the second surface including a diffractive surface, and a lens of glass (22) having the second surface S2 as an aspherical surface and a third surface S3 as an aspherical surface. The lens unit is corrected for the chromatic aberration on an image surface on the optical axis with respect to the light of a reference wavelength not larger than 420 nm within several nm of the reference wavelength, with the numerical aperture of the lens unit being not less than 0.8. This objective lens unit is able to converge the laser light to close to the limit of diffraction on the image surface.

Abstract: An optical head used for recording/reproducing information signals for an optical disc having a light transmitting layer on a recording layer includes an actuator for the collimator lens. A collimator lens arranged between a light source and an objective lens is moved by the actuator for the collimator lens in a direction of cancelling the spherical aberration ascribable to thickness errors in the light transmitting layer. By this structure, the amount of generation of spherical aberration is reduced even if the numerical aperture NA of the objective lens loaded on the optical head is increased to render it possible to increase the recording capacity of the optical disc.

Abstract: The invention relates to an optical pickup and an optical disk apparatus applicable to, for example, an optical disk apparatus adapted to access a high-density recorded optical disk, so as to realize a simplified structure capable of preventing any characteristic deterioration of a focus error signal caused by horizontal deviation. An optical path length difference generator unit 39 is disposed in an optical path to produce an optical path difference between two luminous fluxes obtained through resolution of return light.

Abstract: A beam reshaping device includes first and second beam converting units having beam converging powers different in two orthogonal directions. The first and second beam converting units are arranged such that conjugate points correspond to each other in the two orthogonal directions, thereby reshaping the sectional form of a laser beam emitted from a laser light source, while effectively preventing occurrence of astigmatism. The beam reshaping device may be applied to an optical head device and which in turn may be used in an optical disk system.

Abstract: The present invention provides a compact recording and reproducing apparatus capable of playing back DVD and CDs including CD-R. This apparatus comprises a means of focusing a light of a first or second wavelength onto a first or second recording media; a first means disposed off the optical axis of the focusing means to generate a light of the first wavelength; a second means disposed on the optical axis of the focusing means to generate a light of the second wavelength; a means of correcting a coma aberration in the light of the first wavelength and guiding the corrected light along the optical axis of the focusing means, and a means of detecting the light of the first or second wavelength reflected from the first or second recording media.

Abstract: An optical head comprising an object lens by which a light beam from a light source is projected so as to converge onto said magneto-optical recording medium, a beam splitter disposed along an optical path between the light source and the object lens, for separating the beam emitted from the light source and a first polarized light component or a second polarized light component different therefrom of a light beam returned from the signal surface of said magneto-optical recording medium via said object lens, and a photodetector for receiving the returned beam separated by the beam splitter, wherein the separation rate of the first component or second component by the beam splitter is not less than 85% and not more than 95%. This configuration enables the optical head to be small-sized, and the returned beam is detected with high precision.

Abstract: An optical head apparatus for a magneto-optical recording medium including a light beam source, an objective lens, a separating optical system, and a photodetector. The objective lens is provided for irradiating an output light beam from the light beam source as a focused light beam to the surface of the signal recording surface of the magneto-optical recording medium. The separating optical system separates the light beam radiated from the light beam source from a reflected light beam reflected by the signal recording surface of the magneto-optical recording medium via the objective lens. The photodetector receives the reflected light beam thus separated by the separating optical system. The separating optical system also includes an enhancement element which apparently increases the Kerr rotation angle of the reflected light beam.

Abstract: An optical pickup apparatus for recording information signals on an optical recording medium. The apparatus includes a light source radiating a diverging light flux, an object lens on which a light flux radiated from said light source is incident, for converging the light flux on the optical recording medium, a light flux dividing device arranged at a position on a light path between the light source and the object lens at which the light flux remains a diverging light flux, which light flux dividing device divests reflected light flux from the optical recording medium out of the light path, a light detection unit for detecting the reflected light diverted from the light path by the light flux dividing device, and a polarized light dependent light flux separating device arranged at a position on a light path between the light flux dividing device and the light detection device at which the reflected light flux is a converging light flux.

Abstract: In an optical disc player or other apparatus in which a light beam is directed against a record medium surface for optically reading video or audio information recorded in a track on such surface; an optical scanning assembly is provided with an objective lens interposed in the path of the light beam with its optical axis coinciding substantially with such path therethrough, a lens holder including a first tubular member having the objective lens mounted therein and a second tubular member supporting the first member for rectilinear sliding movement relative thereto in a first direction parallel to the optical axis, a base member supporting the second tubular member of the lens holder for rectilinear sliding movement relative thereto in a second direction at right angles to the first direction, for example, in a direction across or along the track in which information is recorded, first and second coils mounted on the lens holder and being independently energizable, and permanent magnets for producing magneti