Abstract: An optical-pickup apparatus comprising: a polarization beam splitter fixed to a base, which includes a first prism that laser light emitted from a laser diode enters, a second prism that return light of the laser light reflected from a signal recording layer of an optical disc enters, and a control film that is formed on either one of opposed surfaces of the first and second prisms so that the laser light and the return light are selectively passed through or reflected from the control film, the opposed surfaces being opposed to each other; and first and second positioning pins provided on the base to position the polarization beam splitter, the polarization beam splitter being fixed to the base in a state where the opposed surface of at least one of the first and second prisms is made in contact with at least one of the first and second positioning pins.

Abstract: An optical pickup apparatus includes: a laser diode configured to emit a laser beam; and an objective lens configured to condense the laser beam into a laser spot through which a signal recorded on a signal recording layer of an optical disc is read out by the laser beam, the objective lens having formed thereon a lens surface with a second numerical aperture for acting as a lens, which is larger than a first numerical aperture for forming the laser spot.

Abstract: An optical pickup apparatus comprises: a first laser diode that generates a first laser beam having a first wavelength; a second laser diode that generates a second laser beam having a second wavelength longer than the wavelength; a third laser diode that generates a third laser beam having a third wavelength longer than the first wavelength and shorter than the second wavelength; an objective lens having an inner, outer, intermediate regions on an incident surface, the first laser beam being condensed on a signal recording layer of a first optical disc by condensing actions of the inner and outer regions, the second laser beam being condensed on a signal recording layer of a second optical disc by condensing actions of the inner and intermediate regions, the third laser beam being condensed on a signal recording layer of a third optical disc by condensing actions of the inner and intermediate regions.

Abstract: An optical pickup apparatus, which reads signals recorded on first and second signal recording layers of an optical disc, includes: a laser diode; an objective lens to condense a laser beam to the first and second signal recording layers; and a collimating lens disposed in a light path of the laser beam between the laser diode and the objective lens and configured to correct a spherical aberration by moving in a light axis direction of the laser beam, and the objective lens includes a bifocal lens and is configured such that a second focal point does not coincide in position with the second signal recording layer when a first focal point coincides in position with the first signal recording layer, and the first focal point does not coincide in position with the first signal recording layer when the second focal point coincides in position with the second signal recording layer.

Abstract: An optical pickup apparatus including a first objective lens that focuses first laser light on an information recording layer of a first optical disc in a first mounting state where the first optical disc is mounted on a turntable; a second objective lens that focuses second laser light on an information recording layer of a second optical disc in a second mounting state where the second optical disc is mounted on the turntable, the second optical disc having an information recording format different from that of the first optical disc; and a lens holder that integrally holds the first objective lens and the second objective lens in an adjacent manner on the outside and inside, respectively, along a radial direction of the first optical disc in the first mounting state and of the second optical disc in the second mounting state.

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 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 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.

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: An optical pickup apparatus comprising: a laser diode; an objective lens made of synthetic resin arranged in an optical path of laser light between the laser diode and an optical disc so that the laser light from the laser diode is focused onto a signal recording layer through a protection layer of the optical disc; and an aberration correction element interposed in an optical path of the laser light between the laser diode and the objective lens, the aberration correction element configured to be operated so as to correct spherical aberration caused by moisture-absorption characteristics of the objective lens.

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 objective lens holding device includes a first objective lens, a second objective lens, and a lens holder, wherein an axis-to-axis distance between a central axis of the first objective lens and a central axis of the second objective lens is set to a distance, depending on a first length and a second length, which distance prevents a second edge portion from butting against a turntable when the first objective lens focuses light from a first laser on an innermost circumference of the information recording layer of an optical disc.

Abstract: An optical pickup apparatus comprising: a diffraction grating configured to diffract laser light from a laser diode so that signals recorded in first and second optical discs are selectively reproduced, thicknesses of protective layers between surfaces and signal recording surfaces of the first and second optical discs being different from each other; a polarization beam splitter configured to divide laser light from the diffraction grating into first and second laser lights whose light amounts are substantially the same; a first objective lens configured to focus the first laser light onto the signal recording surface of the first optical disc; a second objective lens configured to focus the second laser light onto the signal recording surface of the second optical disc; and a photodetector configured to be applied with return lights of the first and second laser lights reflected from the signal recording surfaces of the first and second optical discs.

Abstract: A method of manufacturing a synthetic resin lens, comprising: adjusting a degree of change in transmittance of a lens member made of synthetic resin for a blue violet laser beam with accumulated application of the blue violet laser beam, by applying to the lens member an electromagnetic wave shorter in wavelength than the blue violet laser beam.

Abstract: An optical-pickup apparatus comprising: a laser diode; an objective lens made of a synthetic resin to focus laser light emitted from the laser diode onto a signal-recording layer of an optical disc; a collimating lens that is arranged in an optical path between the laser diode and the objective lens, and is so movable in an optical axis direction of the laser light as to correct spherical aberration; a temperature sensor to detect a temperature of the objective lens; and an aberration-correcting device to move the collimating lens from a first position where the spherical aberration is a predetermined value on a positive side to a second position where the spherical aberration is a predetermined value on a negative side, when an amount of change in temperature detected by the temperature sensor reaches a predetermined amount after an operation of reproducing a signal from the signal-recording layer is started.

Abstract: An optical pickup apparatus comprising: a laser diode; an objective lens made of a synthetic resin configured to focus laser light emitted from the laser diode to a signal recording layer of an optical disc; and a collimating lens having a diffraction grating and arranged in an optical path between the laser diode and the objective lens, the collimating lens being so moved in an optical axis direction of the laser light as to correct spherical aberration occurring in response to a change in temperature when performing a recording operation for the optical disc, and the collimating lens correcting by the diffraction grating chromatic aberration occurring when switching from the recording operation to a reproducing operation for the optical disc.

Abstract: An optical pickup apparatus comprising: a laser diode; an objective lens configured to focus laser light emitted from the laser diode on a signal recording layer of an optical disc; a first aberration correction element arranged in an optical path between the laser diode and the objective lens; and a second aberration correction element arranged in the optical path between the laser diode and the objective lens and having an aberration correction speed lower than the aberration correction speed of the first aberration correction element, the first aberration correction element and the second aberration correction element being selectively operated according to the required aberration correction speed.

Abstract: An optical-pickup apparatus comprising: a polarization beam splitter fixed to a base, which includes a first prism that laser light emitted from a laser diode enters, a second prism that return light of the laser light reflected from a signal recording layer of an optical disc enters, and a control film that is formed on either one of opposed surfaces of the first and second prisms so that the laser light and the return light are selectively passed through or reflected from the control film, the opposed surfaces being opposed to each other; and first and second positioning pins provided on the base to position the polarization beam splitter, the polarization beam splitter being fixed to the base in a state where the opposed surface of at least one of the first and second prisms is made in contact with at least one of the first and second positioning pins.

Abstract: An optical pickup apparatus comprising: a diffraction grating that a laser beam enters, the diffraction grating being configured to generate a main beam that is 0th order light and sub-beams that are +1st order diffracted light and ?1st order diffracted light; an objective lens configured to focus the main beam and the sub-beams onto a signal recording layer; a main-beam light-receiving portion that the main beam reflected by the signal recording layer is applied to; and sub-beam light-receiving portions that the sub-beams reflected by the signal recording layer are respectively applied to, each light-receiving area of the sub-beam light-receiving portions being smaller than a light-receiving area of the main-beam light-receiving portion.