Abstract: An optical pickup apparatus comprising: a laser diode emitting laser light having a first wavelength; an objective lens focusing the laser light having the first wavelength emitted from the laser diode to each signal recording layer of a first optical disc for which the laser light having the first wavelength is specified as laser light for reproducing a signal and a second optical disc for which laser light having a second wavelength different from the first wavelength is specified as laser light for reproducing a signal; and a spherical aberration correction element disposed in an optical path between the laser diode and the objective lens, the spherical aberration correction element correcting each spherical aberration of the first optical disc and the second optical disc to reproduce a signal recorded in each signal recording layer of the first optical disc and the second optical disc.

Abstract: An optical pickup apparatus comprising: an objective lens focusing laser light emitted from a laser diode to a signal recording layer of an optical disc; a photodetector including a substantially square light-receiving region made of first to fourth sensors divided by boundaries in a first direction corresponding to a tracking direction and a second direction crossing the first direction, the light-receiving region being irradiated with reflected light of the laser light which is reflected from the signal recording layer thereof; and a half mirror reflecting the laser light in a direction of the objective lens and allowing the reflected light to pass therethrough in a direction of the photodetector, the boundary in the second direction for dividing the first to fourth sensors in the light-receiving region being set according to a shape of a spot of the reflected light directly applied from the half mirror to the light-receiving region.

Abstract: A lens holder is disclosed which holds a plurality of objective lenses, the lens holder holding the plurality of objective lenses so as to be arranged with a composite gravity center position of the plurality of objective lenses matching a gravity center position of the entire lens holder without the plurality of objective lenses.

Abstract: An optical pickup apparatus comprising: a collimating lens configured to convert laser light emitted from a laser diode, from diffused light into parallel light; an objective lens; and a prism configured to guide the laser light emitted from the collimating lens to the objective lens, the prism including: a first face that the laser light emitted from the collimating lens enters; a second face that reflects the laser light entering the first face; and a third face that reflects the laser light reflected from the second face in a direction of the second face, and emits the laser light reflected again from the second face in a direction of the objective lens.

Abstract: An optical member driving apparatus comprising: a holding member configured to have an optical member mounted thereon; a driving unit assembly configured to be capable of driving the holding member; a connecting member configured to connect the holding member and the driving unit assembly; and a jointing member configured to joint the connecting member and either or both of the holding member and the driving unit assembly.

Abstract: A photodetector comprising: a substrate; a photodiode fixed to the substrate, the photodiode configured to output a signal according to a light amount of a laser beam when applied with the laser beam; and a translucent resin covering the photodiode, the translucent resin being irradiated with ultraviolet light in advance for a predetermined time such that a change in transmittance of the translucent resin for the laser beam having a predetermined wavelength is set within a predetermined range.

Abstract: An optical pickup apparatus comprising: a first objective lens; and a second objective lens arranged with the first objective lens in a radial direction of an optical disc, the first objective lens being configured to focus laser light for reproduction, which is laser light for reproducing a signal recorded in a signal recording layer of the optical disc, onto the signal recording layer, the second objective lens being configured to focus laser light for recording, which is laser light for recording a signal, onto the signal recording layer.

Abstract: An objective lens formed of a synthetic resin material having characteristics of substantially not reducing transmittance of the objective lens when a first laser beam having a first wavelength passes through the objective lens, and reducing the transmittance according to an elapsed time to apply a second laser beam when the second laser beam having a second wavelength shorter than the first wavelength and longer than a wavelength of ultraviolet light passes through the objective lens, the objective lens being irradiated with the ultraviolet light in advance for a predetermined time such that a change in the transmittance for the second laser beam is set within a predetermined range.

Abstract: An optical pickup apparatus comprising: a collimating lens configured to convert laser light having Gaussian distribution property emitted from a laser diode from divergent light to parallel light; an objective lens configured to focus the laser light from the collimating lens onto a signal recording layer of an optical disc; and an adjustment film formed on a surface of an incident face of the collimating lens on which the laser light is incident, and configured to adjust transmittance of the laser light passing through the collimating lens, the adjustment film being formed on the surface of the incident face so that the transmittance is lower on the inner side of the incident face than on the outer side of the incident face.

Abstract: An optical pickup apparatus comprising: an objective lens formed so that a first and second laser beams different in wavelength are respectively focused onto signal recording layers of a first and second optical discs; and a photodetector including a square-shaped light-receiving portion for being irradiated with return light, as a spot, of the first or second laser beam respectively reflected from the signal recording layers of the first or second optical discs, to generate a focus error signal, a length of a diagonal line of the light-receiving portion being substantially equal to a longer diameter of an elliptical spot formed in a direction of the diagonal line when the focus error signal is at a maximum level for an optical disc that is either one of the first and second optical discs, to which a laser beam shorter in wavelength out of the first and second laser beams is focused.

Abstract: A lens driving apparatus includes a first lens-barrel having a lens built thereinto; a second lens-barrel; an electromechanical conversion element that applies a driving force f1 to the first lens-barrel and a driving force f2 to the second lens-barrel; and a housing that supports the lateral surfaces of the first lens-barrel and the second lens-barrel such that a lens-barrel body is mounted slidably on the housing in the light axis direction of the lens, the lens barrel body being the first lens-barrel and the second lens-barrel connected via the electromechanical conversion element therebetween, wherein the electromechanical conversion element generates deformation which results in displacement in the light axis direction of the lens by applying a drive voltage.

Abstract: An optical pickup configured so as to reproduce signals recorded in optical disks of plural standards by means of a single laser beam. The optical pickup has an objective lens for gathering a laser beam emitted from a semiconductor laser—which emits a laser beam of single wavelength—onto a signal recording layer provided in each of optical disks of first and second standards whose cover layers differ from each other in terms of a thicknesses. The first standard is; for example, a CD, and the second standard is; for example, a DVD. An optical path length correction member—in which there is formed an optical path length correction section for making a correction to an optical path length falling within a range smaller than the diameter of a light beam passing through the objective lens—is provided in an optical path between the semiconductor laser and the objective lens. The optical path length correction section may also be formed on a lens plane of the objective lens facing the semiconductor laser.

Abstract: An optical disk apparatus includes: a semiconductor laser which emits laser light; a focusing unit which focuses the laser light emitted from the semiconductor laser onto an optical disk; a detector which receives reflected light from the optical disk; a drive unit which rotates the optical disk; and a control unit which controls the semiconductor laser and the drive unit. When the optical disk is reproduced, the control unit causes the semiconductor laser to emit the laser light by a first power realizing a relative intensity noise tolerable for the reproduction of the optical disk. And the control unit causes the drive unit to rotate the optical disk at a first linear velocity which is free from reproduction light deterioration when the semiconductor laser emits the laser light by the first power.

Abstract: An optical pickup apparatus comprising: an objective lens configured to focus laser light having the Gaussian distribution properties emitted from a laser diode to a signal recording layer of an optical disc; and an adjustment coating formed on a surface of an incident face of the objective lens on which the laser light is to be made incident, the adjustment coating being configured to adjust transmittance of the laser light passing through the objective lens, the adjustment coating being formed on the surface of the incident face such that the transmittance is lowered as a numerical aperture of the objective lens is reduced.

Abstract: An optical pickup apparatus reading signal recorded on signal recording layer of first and second optical discs different in distance from incident surface of laser light to the layer, comprising: an objective lens to be changed in numerical aperture for reading signal from the discs; a focus coil to displace the lens in direction toward surfaces of the discs; a tracking coil to displace the lens in radial direction of the discs; a tilt coil to correct optical-axis angle of the lens to the surfaces; a numerical aperture changing element to change the numerical aperture so that the light is focused on the layers of the discs; an incident angle changing element to change incident angle of the light to the lens so that the light is focused on the layers; and a tilt control unit to control driving of the tilt coil to correct coma aberration.

Abstract: An optical pickup device for reading a signal recorded in an optical disc including a first signal recording layer and a second signal recording layer, comprising: a laser diode configured to emit laser light; and a diffraction grating configured to be applied with laser light emitted from the laser diode, and to generate a main beam including zero order light, and a sub beam including plus first order light and minus first order light, such that a ratio of light amount of the sub beam to that of the main beam is substantially 1:7.

Abstract: A lens holder is disclosed which holds a plurality of objective lenses, the lens holder holding the plurality of objective lenses so as to be arranged with a composite gravity center position of the plurality of objective lenses matching a gravity center position of the entire lens holder without the plurality of objective lenses.

Abstract: A photodetector to be incorporated in an optical pickup device, comprising: a photodiode that a laser light emitted from a laser diode is applied to and that outputs a signal corresponding to light amount of the laser light; and a translucent resin member configured to cover the photodiode, including a light receiving portion that the laser light is applied to and that causes the laser light to be applied to the photodiode, and a peripheral portion provided around the light receiving portion, the light receiving portion being smaller in thickness than the peripheral portion.

Abstract: A photodetector comprising: a first light-receiving surface configured to receive reflected light of zero-order light generated based on a laser beam, from one information recording layer of a multilayer optical disc; a second light-receiving surface that is adjacent to the first light-receiving surface with a predetermined interval, the second light-receiving surface being configured to receive reflected light of diffracted light generated based on the laser beam, from the one information recording layer; and a third light-receiving surface for canceling out reflected light of the zero-order light from other information recording layer of the multilayer optical disc, received by the first light-receiving surface or the second light-receiving surface, the third light-receiving surface being configured to receive the reflected light of the zero-order light from other information recording layer.

Abstract: An objective lens focusing light emitted from a light source onto an information surface of an optical disk, comprising: a first lens surface to be positioned on the light-source side; a second lens surface to be positioned on the optical-disc side; a first edge surface to be positioned on the light-source side, provided in an outer region of the first lens surface; and a second edge surface to be positioned on the optical-disc side, provided in an outer region of the second lens surface, a first optical axis of the first lens surface coinciding with a second optical axis of the second lens surface, the first optical axis and the second optical axis being orthogonal to the second edge surface.