Abstract: The present disclosure provides an oxygen storage/release material that has achieved both the improved oxygen storage/release capacity at low temperature and heat tolerance, which comprises a ceria-zirconia-based composite oxide, wherein the ceria-zirconia-based composite oxide further comprises praseodymium (Pr) or neodymium (Nd), and has, in at least a part thereof, at least one ordered phase of ? phase and a pyrochlore phase, a proportion of primary particles having particle diameters of 0.4 ?m to 1.5 ?m is 40% to 100% on a particle number basis, and, when heated for 5 hours in the air at 1,100° C., I(14/29) value is 0.015 or more and I(28/29) value is 0.08 or less. The present disclosure also relates to a method for producing such oxygen storage/release material.

Abstract: A release sheet, on which a stamper receiving layer for producing an optical recording medium is laminated, comprising a release agent layer on a side to which the stamper receiving layer is laminated, wherein the release agent layer is formed using a release agent that contains an organopolysiloxane (other than an MQ resin below) containing an alkenyl group in the molecule, an MQ resin containing an alkenyl group and having, as constituent components, M units represented by formula (1) R12R2—Si—O—??(1) (where, R1 denotes an organic group and R2 denotes an alkenyl group), and Q units represented by formula (2) and a cross-linking agent, and that does not substantially contain particles consisting of inorganic matter, and the alkenyl group content in said MQ resin ranges from 0.5 to 5 wt %. The release sheet can reduce concave defects on a convex-concave pattern transfer surface of the stamper receiving layer.

Abstract: An optical pickup device includes a diffraction grating 12 for separating a light beam emitted from a semiconductor laser element into at least three light beams. The diffraction grating 12 is divided into three regions by a straight line extending in a direction parallel to a tangent line of a track of an optical information recording medium. A second region 12B is divided into a first sub-block 13 and a second sub-block 14 by a straight line extending in a direction parallel to a radius direction of the optical information recording medium. The first sub-block 13 has a phase difference of approximately 180 degrees from the second sub-block 14. The first region 12A has a phase difference of approximately 90 degrees from the first sub-block 13 and has a phase difference of approximately 180 degrees from the third region 12C.

Abstract: An optical pickup device includes a diffraction grating 12 for separating an emitted light beam into at least three light beams. The diffraction grating 12 is divided into three regions by dividing lines D1 and D2 extending in a first direction parallel to a tangent line of a track of an optical information recording medium. A second region 12B is divided into four sub-blocks by a dividing line D3 extending in the first direction and a dividing line D4 extending in a second direction that crosses the first direction. The sub-blocks located diagonally opposite to each other have a same phase, and the sub-blocks located adjacent to each other have a phase difference of approximately 180 degrees. The first region 12A has a phase difference of approximately 90 degrees from each sub-block of the second region 12B, and the first region 12A has a phase difference of approximately 180 degrees from the third region 12C.

Abstract: A pickup device includes a diffraction grating 12 for separating a light beam emitted from the light source into at least three light beams. The diffraction grating 12 is divided into four regions by straight lines extending in a direction parallel to a tangential direction of tracks of an optical information recording medium. A periodic structure of a second region 12B has a phase difference of approximately 180 degrees from a periodic structure of a third region 12C, and a periodic structure of a first region 12A has a phase difference of approximately 180 degrees from a periodic structure of a fourth region 12D.

Abstract: An optical pickup device in which a hologram element has a plurality of different diffraction directions. In the tracking standard state, the hologram element is divided into six areas by a straight line connecting two strength center points of two light beams, and by two straight lines that are perpendicular to the straight line. By adding the amount of light received by an area demarcated by two straight lines that pass the two strength center points, to the amount of light received by one of two outer areas sandwiching the area depending on the type of the light beam, it is possible to obtain a well-balanced tracking error signal for each of the two light beams.

Abstract: A pickup device includes a diffraction grating 12 for separating a light beam emitted from the light source into at least three light beams. The diffraction grating 12 is divided into four regions by straight lines extending in a direction parallel to a tangential direction of tracks of an optical information recording medium. A periodic structure of a second region 12B has a phase difference of approximately 180 degrees from a periodic structure of a third region 12C, and a periodic structure of a first region 12A has a phase difference of approximately 180 degrees from a periodic structure of a fourth region 12D.

Abstract: An optical pickup device includes a diffraction grating 12 for separating a light beam emitted from a semiconductor laser element into at least three light beams. The diffraction grating 12 is divided into three regions by a straight line extending in a direction parallel to a tangent line of a track of an optical information recording medium. A second region 12B is divided into a first sub-block 13 and a second sub-block 14 by a straight line extending in a direction parallel to a radius direction of the optical information recording medium. The first sub-block 13 has a phase difference of approximately 180 degrees from the second sub-block 14. The first region 12A has a phase difference of approximately 90 degrees from the first sub-block 13 and has a phase difference of approximately 180 degrees from the third region 12C.

Abstract: A pickup device includes a diffraction grating 12 for separating a light beam emitted from the light source into at least three light beams. The diffraction grating 12 is divided into four regions by straight lines extending in a direction parallel to a tangential direction of tracks of an optical information recording medium. A periodic structure of a second region 12B has a phase difference of approximately 180 degrees from a periodic structure of a third region 12C, and a periodic structure of a first region 12A has a phase difference of approximately 180 degrees from a periodic structure of a fourth region 12D.

Abstract: An optical pickup device includes a diffraction grating 12 for separating an emitted light beam into at least three light beams. The diffraction grating 12 is divided into three regions by dividing lines D1 and D2 extending in a first direction parallel to a tangent line of a track of an optical information recording medium. A second region 12B is divided into four sub-blocks by a dividing line D3 extending in the first direction and a dividing line D4 extending in a second direction that crosses the first direction. The sub-blocks located diagonally opposite to each other have a same phase, and the sub-blocks located adjacent to each other have a phase difference of approximately 180 degrees. The first region 12A has a phase difference of approximately 90 degrees from each sub-block of the second region 12B, and the first region 12A has a phase difference of approximately 180 degrees from the third region 12C.

Abstract: A release sheet, on which a stamper receiving layer for producing an optical recording medium is laminated, comprising a release agent layer on a side to which the stamper receiving layer is laminated, wherein the release agent layer is formed using a release agent that contains an organopolysiloxane (other than an MQ resin below) containing an alkenyl group in the molecule, an MQ resin containing an alkenyl group and having, as constituent components, M units represented by formula (1) R12R2—Si—O—??(1) (where, R1 denotes an organic group and R2 denotes an alkenyl group), and Q units represented by formula (2) and a cross-linking agent, and that does not substantially contain particles consisting of inorganic matter, and the alkenyl group content in said MQ resin ranges from 0.5 to 5 wt %. The release sheet can reduce concave defects on a convex-concave pattern transfer surface of the stamper receiving layer.

Abstract: A pickup device includes a diffraction grating 12 for separating a light beam emitted from the light source into at least three light beams. The diffraction grating 12 is divided into four regions by straight lines extending in a direction parallel to a tangential direction of tracks of an optical information recording medium. A periodic structure of a second region 12B has a phase difference of approximately 180 degrees from a periodic structure of a third region 12C, and a periodic structure of a first region 12A has a phase difference of approximately 180 degrees from a periodic structure of a fourth region 12D.

Abstract: An optical pickup device includes: a first light-receiving element for receiving a main beam of a first light beam; second and third light-receiving elements for receiving sub-beams of the first light beam; a fourth light-receiving element for receiving a main beam of a second light beam; and fifth and sixth light-receiving elements for receiving sub-beams of the second light beam. The first through third light-receiving elements are located on a first line with the first light-receiving element sandwiched between the second and third light-receiving elements. The fourth through sixth light-receiving elements are located on a second line with the fourth light-receiving element sandwiched between the fifth and sixth light-receiving elements. The first line and the second line are parallel to each other.

Abstract: An optical pickup device in which a hologram element has a plurality of different diffraction directions. In the tracking standard state, the hologram element is divided into six areas by a straight line connecting two strength center points of two light beams, and by two straight lines that are perpendicular to the straight line. By adding the amount of light received by an area demarcated by two straight lines that pass the two strength center points, to the amount of light received by one of two outer areas sandwiching the area depending on the type of the light beam, it is possible to obtain a well-balanced tracking error signal for each of the two light beams.

Abstract: In an optical head operable to record to and read from an optical recording medium, a beam emitted by a light-emitting element is reflected toward the light-emitting element by a first reflective mirror, and this reflected beam is reflected toward the optical recording medium by a second reflective mirror and focused on a recording surface of the optical recording medium. In this case, the first reflective mirror blocks a principal ray of the beam traveling toward the optical recording medium from the second reflective mirror, and the second reflective mirror consists of a plurality of concentric annular mirrors centered on the principal ray of the beam and separated from each other by a predetermined interval.

Abstract: An optical pickup apparatus including three semiconductor laser devices which emit laser beams of different wavelengths, a beam splitter, a collimator lens, a hologram device, two light receiving devices, a diffraction grating-hologram device, an integrated substrate, a light detection/source unit and diffraction gratings, whereby the three semiconductor laser devices share the beam splitter and the collimator lens.

Abstract: An optical head includes a fixed part, a movable part movably held by a plurality of wires fixed on the fixed part, and magnets fixed to the fixed part. The movable part includes a movable-part housing, a heatsink held by the movable-part housing, a light emitting element and a light receiving element both mounted on the heatsink, magnets provided to both sides of the movable-part housing to contact the heatsink, an objective lens held by the movable-part housing to allow an emitted laser beam from the light emitting element to focus, and a diffraction grating provided between the objective lens and the light emitting element and between the objective lens and the light receiving element. The gap between each coil and the adjacent magnet is filled with ferrofluid having a higher thermal conductivity than the atmosphere.

Abstract: An optical pickup having a light-emitting element, an objective lens unit, a reflecting mirror and a light-receiving element, emits a beam onto an optical recording medium and uses a reflected beam to read recorded information. In the objective lens unit, a central part of a surface, facing the light-emitting element, of an objective lens disposed so that an optical axis is substantially aligned with a chief ray of the beam emitted by the light-emitting element, is a transmissive diffraction grating, and a central part of a surface of the objective lens that will face the optical recording medium is a convex mirror which bulges toward the light-emitting element. The reflecting mirror, which is annular and encompasses the optical axis of the objective lens, reflects toward the objective lens the beam from the light-emitting element that has passed through the transmissive diffraction grating and been reflected by the convex mirror.

Abstract: An optical pickup includes: two laser diodes respectively operable to emit optical beams having different wave lengths; a diffraction grating operable to diffract each optical beam to a zero order diffracted beam and plus and minus first order diffracted beams; a holographic optical element operable to diffract the beams reflected from a recording medium; and photoelectric devices operable to receive the beams diffracted by the holographic optical element, wherein a photoelectric device for generating a tracking error signal and a photoelectric device for generating a focus error signal are disposed on opposite sides with respect to the laser diodes so as to face each other.

Abstract: An optical pickup having a light-emitting element, an objective lens unit, a reflecting mirror and a light-receiving element, emits a beam onto an optical recording medium and uses a reflected beam to read recorded information. In the objective lens unit, a central part of a surface, facing the light-emitting element, of an objective lens disposed so that an optical axis is substantially aligned with a chief ray of the beam emitted by the light-emitting element, is a transmissive diffraction grating, and a central part of a surface of the objective lens that will face the optical recording medium is a convex mirror which bulges toward the light-emitting element. The reflecting mirror, which is annular and encompasses the optical axis of the objective lens, reflects toward the objective lens the beam from the light-emitting element that has passed through the transmissive diffraction grating and been reflected by the convex mirror.