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 includes: a laser diode having a first-laser element, which emits a first-laser beam, and a second-laser element, which emits a second-laser beam having a wavelength shorter than a wavelength of the first-laser beam, arranged in the same package; an objective lens to condense the first- and second-laser beams emitted from the laser diode to signal-recording layers of first- and second-optical discs, respectively, the second-optical disc being of a standard different from a standard of the first-optical disc; and a collimating lens arranged in an optical path between the laser diode and the objective lens, the collimating lens configured to change the first- and second-laser beams from divergent light to parallel light, the collimating lens being inclined with respect to optical axes of the first- and second-laser beams so that astigmatism in the first- and second-laser beams is corrected.

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: An objective lens includes: a diffraction area having a diffraction structure provided thereon concentrically around an optical axis of the objective lens; and a first non-diffraction area provided outward an outer circumference of the diffraction area, the objective lens being configured to focus first laser light on a signal recording surface of a first optical recording medium by refraction in the first non-diffraction area; focus second laser light, different in wavelength from the first laser light, on a signal recording surface of a second optical recording medium by diffraction in the diffraction area; and focus third laser light, different in wavelength from the first laser light and the second laser light, on a signal recording surface of a third optical recording medium by diffraction in the diffraction area.

Abstract: An optical pickup apparatus includes: a laser diode configured to generate a laser beam; and an objective lens having an annular diffraction zone formed on an incident surface thereof on which the laser beam is incident, the annular diffraction zone being a zone configured to focus the laser beam on each of signal recording layers of first to third optical discs so that a signal recorded in each of the signal recording layers of the first to third optical discs are read, the first optical disc having the signal recording layer at a first distance from a surface thereof, the second optical disc having the signal recording layer at a second distance longer than the first distance from a surface thereof, the third optical disc having the signal recording layer at a third distance longer than the first distance and shorter than the second distance from a surface thereof.

Abstract: An optical-pickup apparatus includes: a first-objective lens; a second-objective lens; a lens holder including a first-lens barrel having the first-objective lens mounted on an end face thereof and a second-lens barrel having the second-objective lens mounted on an end face thereof; an actuator unit having the lens holder mounted thereon; and a housing having the actuator unit mounted thereon, the first and second objective lenses each being mounted on the lens holder such that a direction, in which wavefront of coma aberration on each lens face is most advanced in phase, is aligned with a radial direction of an information-recording medium, the actuator unit being mounted on the housing such that an optical axis of the first-objective lens is inclined in the radial direction at an inclination angle of the axis toward a recording surface of the medium required to cancel coma aberration of the first-objective lens to the surface.

Abstract: In the present invention, to improve CD read/write characteristics having poor image height characteristics, a third light emitting source emitting a third laser beam for CD is disposed on an optical axis of an objective lens. Thereby, the third laser beam emitted from the third light emitting source travels along the optical axis of the objective lens, thus generating no coma aberration in the third laser beam. Furthermore, in the present invention, a second light emitting source emitting a second laser beam for DVD and a first light emitting source emitting a first laser beam for BD are disposed across the third light emitting source. Thereby the phase propagation directions of coma aberrations in the first and second laser beams coincide with each other. Adjustment of the coma aberration in one of the laser beams enables the coma aberration in the other laser beam to be adjusted.

Abstract: An optical-pickup apparatus includes: a three-wavelength-laser diode including first-, second-, and third-laser elements to emit first-, second-, and third laser beams having first, second, and third wavelengths, respectively, the three laser elements housed in the same case; an objective lens to focus the three laser beams onto first- to third-optical-disc-signal-recording layers, respectively; a first photodetector to be irradiated with first-return light reflected from the first-optical-disc-signal-recording layer, a second photodetector to be irradiated with second- and third-return lights respectively reflected from the second- and third-optical-disc-signal-recording layers; a polarizing-beam splitter to reflect the three laser beams toward the lens, and allow the three return lights having passed through the lens to pass therethrough; a semitransparent mirror on which the three return lights having passed through the polarizing-beam splitter are incident, and which guide the first-return light toward th

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 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 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 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 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 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.