Abstract: An optical scanning device for scanning an information layer of a first optical record carrier having a first cover layer thickness and an information layer of a second optical record carrier having a second, different cover layer thickness. The device includes an objective lens system for converging a radiation beam on the information layers. The objective lens system includes a first lens element and a second lens element spaced apart along an optical axis. The objective lens system further includes a switchable optical element comprising a first fluid, and a chamber positioned between said first lens and said second lens.

Abstract: There is provided a recording/playback device able to differentiate the type of an optical disc or another such optical recording medium with a high degree of precision while correcting wavefront aberrations. The recording/playback device has a detection part for sequentially detecting the surface of a cover layer and one or a plurality of signal recording surfaces of an object to be detected on the basis of an output signal of a photodetector, a medium differentiation part for differentiating the type of the detected object on the basis of the detection results, an aberration correction element, and an aberration control part for controlling the aberration correction state of the aberration correction element.

Abstract: An optical pickup and a recording and/or reproducing apparatus having the same, the optical pickup including: a light source emitting a light beam; an objective lens focusing the emitted light beam onto a multi-layered optical information storage medium; a polarization dependent optical path changer changing a proceeding path of the light beam; a photodetector detecting a signal beam reflected from the optical information storage medium; and a polarization element provided on an optical path of the reflected signal beam, and reducing interference between the signal beam and a noise beam reflected from an adjacent layer on a light receiving plane by changing a polarization state of the signal beam in at least a portion where the signal beam overlaps with the noise beam.

Abstract: There is provided a coupling lens used in an optical information recording/reproducing device for recording information to and/or reproducing information from an optical disc. The coupling lens includes a first surface and a second surface, wherein the coupling lens is configured to satisfy a following condition (1): ?0.80?Z?0.40 ??(1), wherein a value Z is obtained from a following equation (E1): Z = ? ? n ? ( L ? ) L ? = ( A - B ) ( D - E ) - ( F - G ) ( H - I ) .

Abstract: A spherical aberration correction mechanism includes a plurality of aberration correction lenses, a movable portion in which the aberration correction lens is held, a fixed portion in which the movable portion is arranged so as to be slidable as well as the aberration correction lens is held, a shaft supporting the movable portion so as to be rotatable about the axis as well as to be slidable in the axial direction, a feed screw having spiral grooves, an engaging portion having convex portions to be engaged with the spiral grooves from one direction and a coil spring fitted to the outside of the shaft, pressing the movable portion in the axial direction. The coil spring has a rotation prevention portion engaged with the fixed portion and a torque biasing portion engaged with the movable portion, and the coil spring is installed in a twisted state in advance.

Abstract: An optical system includes an optical recording medium configured to store data and a light device configured to emit a beam of light to write the data to the optical recording medium or read the data from the optical recording medium. The optical system also includes a superlens positioned between the optical recording medium and the light device. The superlens is configured to focus the beam of light emitted from the light device to create a focused beam of light on the optical recording medium.

Abstract: An optical pickup is provided with a protector which prevents collision between an objective lens and an optical recording medium. The protector includes: a first sheet material which is arranged on an uppermost layer, has durability for abrasion against the collision with the optical recording medium that rotates in high speed, and is softer than a protecting member that protects a recording surface of the optical recording medium; a second sheet material which is provided in lower side than the first sheet material and has elasticity; and a plurality of adhesive sheets to perform adhesion between the sheet materials that form the protector, or adhesion between the lowermost sheet material among the sheet materials and a lens holder which holds the objective lens, or the objective lens.

Abstract: An optical pickup lens includes a first surface to focus laser light for recording/playback on an optical disc, a second surface formed outside the first surface and radiated with laser light for lens tilt detection, and an antireflection coating to transmit the laser light for recording/playback, the antireflection coating being continuously formed on the first surface and a second surface.

Abstract: A system for applications, such as imaging, lithography, data storage, and inspection, includes an optical element, at least one structure, and a source of light. The structure is at least partially in and at least adjacent a surface of the optical element. The source of light has a mode profile that provides an electric field which has a vector component substantially perpendicular to a surface of the optical element. The source of light is positioned to propagate at least a portion of the light through the optical element onto the object. The structure enhances the electric field of the light which optically interacts with the object.

Abstract: An optical head comprises first and second light sources which are arranged next to each other and emit lights of different wavelengths and an optical device which is arranged between the first and second light sources and a conversing lens for reducing the spherical aberration caused by combination of the conversing lens and at least one of first and second optical recording media which correspond to at least one of the lights of first and second wavelengths. The optical axis of the optical device is shifted with respect to the optical axis of the conversing lens in order to reduce the coma aberration that is caused since at least one of optical axes of the lights of first and second wavelengths does not coincide with the optical axis of the conversing lens.

Abstract: A recording medium includes a substrate having a microscopic pattern, which includes a shape of continuous substance of approximately parallel grooves formed with a convex shaped section and a concave shaped section alternating on a surface of the substrate. A recording layer is formed on the microscopic pattern and a light transmitting layer has a thickness of 0.05 mm to 0.12 mm formed on the recording layer. The microscopic pattern satisfies a relation of P??/NA, wherein P is a pitch of the convex shaped section, ? is a wavelength of a reproducing light beam and NA is a numerical aperture of an objective lens. The microscopic pattern also includes modulated address information formed on both side walls of the convex shaped section viewed from the light transmitting layer as a wobble, both the side walls being parallel to each other, and furthermore wherein the address information is modulated by the phase-shift keying modulation system.

Abstract: An objective-lens driving device includes a fixed block fixed to a moving base, a movable block having a lens holder configured to hold objective lenses, support springs configured to connect the fixed block and the movable block to each other, a focusing magnetic circuit including a first focusing coil, a second focusing coil, a first focusing magnet, and a second focusing magnet, and a tracking magnetic circuit. The first focusing coil is attached to the lens holder such that a first thrust-generating portion and a second thrust-generating portion are spaced from each other in a tangential direction. The second focusing coil is attached to the lens holder such that an axial direction of the second focusing coil coincides with the tangential direction. The first focusing magnet and the second focusing magnet are arranged in the tangential direction with the movable block disposed therebetween.

Abstract: The present invention provides an object lens actuator, an optical pickup, and an optical disk drive, which can increase the size of the object lens actuator driving a lens holder in the tangential tilt direction, and drive and control the lens holder with a small amount of drive current. An object lens actuator comprising a lens holder having an object lens and a first coil; a first magnet fixed to a yoke; plural elastic support parts for supporting said lens holder with a first fulcrum; a moving part for supporting said elastic support parts with a second fulcrum different from said first fulcrum, and a fixed part having a moving mechanism for moving said moving part, wherein said first coil and said first magnet constitute a first magnetic circuit, said first magnetic circuit makes said lens holder movable in a focusing direction, a tracking direction and a radial tilt direction of an optical disk for read/write, and said moving mechanism makes said moving part movable.

Abstract: According to one embodiment, an optical recording head device includes a light source which outputs such a relaxation oscillation optical pulse that a full width at half maximum of a single pulse is 820 ps or less, a driving unit for driving the light source, an objective lens which converges emission light from the light source on a recording layer of a recording medium, and captures reflective light which is reflected by the recording layer of the recording medium, a distribution unit, placed between the light source and the objective lens, for distributing incident light, and a photodetection unit for receiving via the distribution unit the reflective light which is reflected by the recording layer of the recording medium, wherein a resonator length of the light source is 6560 ?m or less.

Abstract: A laminated wave plate that corresponds to a plurality of wavelengths including at least two wavelengths of ?A and ?B, and includes a first wave plate disposed on an incident side and a second wave plate disposed on an emitting side, the first wave plate and the second wave plate being laminated in such a manner that their optical axes are intersected each other, includes the following equations from (1) to (5): ?A1=360°+360°×2NA ??(1); ?A2=180°+360°×NA ??(2); ?B1=360°×2NB ??(3); ?B2=360°×NB ??(4); and NB=(?nB/?nA)×(?A/?B)×(0.

Abstract: Each of sensors (16a, 16b) has a light-receiving portion and a light-emitting portion and outputs a signal according to light received by the light-receiving portion. The sensors (16a, 16b) face an actuator movable portion (26) in the tangential direction. The sensors (16a, 16b) are symmetrically arranged with respect to the centerline of the actuator movable portion (26) in the radial direction. When the actuator movable portion (26) is displaced in the radial direction, an output of one of the sensors (16a, 16b) is greater than an output of the other. Then, the difference between the two outputs is obtained to detect the displacement of the actuator moving part (26) in the radial ditection.

Abstract: A disclosed optical pickup for performing at least recording, reproduction, or deletion of information on a first, second, third, and fourth optical recording media having different recording densities includes a first light source configured to emit first light having a first wavelength ?1 corresponding to the first and second optical recording media; a second light source configured to emit second light having a second wavelength ?2 corresponding to the third optical recording medium; a third light source configured to emit third light having a third wavelength ?3 corresponding to the fourth optical recording medium; an objective lens configured to focus the first light, the second light, and the third light on corresponding recording surfaces of the first, second, third, and fourth optical recording media; and an aberration correcting unit between the objective lens and the first, second, and third light sources.

Abstract: An optical pickup apparatus includes: a light-emitting element for emitting laser light; a collimating lens for causing incident laser light to be converted into an optical beam and for emitting the optical beam thus converted; an objective lens for converging onto a recording surface of a recording medium the optical beam from the collimating lens; a light-receiving element for receiving reflected light from the recording medium; a collimating lens holder for holding the collimating lens; supporting means for supporting the collimating lens holder so that the collimating lens holder can freely move in an optical axis direction of the collimating lens; driving means for driving the collimating lens holder by electromagnetic force; and an elastic member, provided between a housing and the collimating lens holder, for pulling back the collimating lens holder to a neutral position in the optical axis direction of the collimating lens.

Abstract: The present invention relates to a data transmission optical device including a source emitting a laser beam for transmitting the data toward an optical sensor. The device has means for collimating the beam. It may be implemented on board an aircraft for transmitting audio or video data to the passenger seats. The device has applications for on-demand video.

Abstract: An optical system utilized in an optical pickup apparatus comprising: an aberration-correcting element made of a plastic material; and a converging lens to converge a light flux emitted from the aberration-correcting element, the converging lens being made of a plastic material, wherein the aberration-correcting element has a first optical surface provided thereon an optical path difference generating structure and has a second optical surface provided thereon a diffractive structure, and the converging lens is a single refractive lens having at least an aspherical surface.

Abstract: A hybrid objective lens has a refractive lens and a diffractive optical element constructed by plural coaxial ring-shaped zones on at least one optical surface thereof. When n1, n2 and n3 each is a diffraction order of a diffracted ray having a maximum light amount among diffracted rays of each of first, second and third light flux having wavelength ?1, ?2 and ?3 when respective light flux comes to be incident into the diffractive structure respectively, the following formulas are satisfied: |n1|>|n2|, and |n1|>|n3|, and the hybrid objective lens converges a n1-th, n2-th and n3-th order diffracted ray of the first, second and third light flux onto an information recording plane of each of the first, second ant third optical information recording medium respectively so as to form an appropriate wavefront within respective prescribed necessary image side numerical apertures.

Abstract: A method for evaluating a read signal obtained by irradiating a medium with a laser beam through an objective lens and reading data from the reflected laser beam by a PRML detection method is provided. The method includes: a sampling step of sampling the data obtained from the reflected laser beam at clock timings to obtain sampled values; and a step of, when a constraint length of a PR class in the PRML detection method is an even number, computing an intermediate sampled value for evaluation using at least adjacent two of the sampled values arranged in the order sampled at the clock timings. The provided method is an objective evaluation method when the PRML detection method is used, whereby the selection of a recording medium and a reading apparatus is facilitated.

Abstract: There is provided an objective optical system including an optical element having a phase shift structure, and a single-element objective lens made of resin, wherein the phase shift structure includes a plurality of refractive surface zones, the phase shift structure includes a first area to contribute to converging at least the third light beam on a record surface of the third optical disc, the first area includes at least two types of steps, each of which is formed at a boundary between adjacent ones of the plurality of refractive surface zones, the at least two types of steps gives optical path length differences different from each other to an incident light beam, the annular zone structure satisfies following conditions: 0.01<(EP21?EP11)/EP11<0.10 0.04<(EP31?EP11)/EP11<0.30 ?100<?(?OPD11/?1)+?(?OPD12/?1)<?10 where EP11=INT((?OPD11/?1)+0.5)×(?1(n1?1)), EP21=INT((?OPD21/?2)+0.5)×(?2(n1?1)), EP31=INT((?OPD31/?3)+0.5)×(?3(n1?1)).

Abstract: An objective lens is included in an optical pickup device that records and/or reproduces an information signal onto and/or from an optical recording medium. The objective lens has a numerical aperture of 0.82 or higher, has first and second surfaces that are both aspherical, and focuses a light beam onto the optical recording medium. The first and second surfaces have surface-to-surface eccentricity therebetween that causes an aberration, the aberration being correctable by tilting an optical axis of the objective lens relative to a central axis of the light beam incident on the objective lens. The aberration caused by the surface-to-surface eccentricity includes a third-order coma aberration. When the optical axis is tilted relative to the central axis of the incident light beam so that the third-order coma aberration becomes substantially 0 m? rms, each of astigmatism, spherical aberration, and high-order coma aberration becomes 20 m? rms or less.

Abstract: An optical pickup to improve countermeasure capability of a disc by allowing polarized light of a spot on the disc to become elliptically polarized light includes a light source to emit semiconductor laser light, an objective lens to condense the light emitted from the light source and form an optical spot on a disc, and a wave plate which is rotated such that the spot formed on the disc becomes elliptically polarized light.

Abstract: An optical pickup includes an objective lens, a protection member for protecting the objective lens, and a lens holding member configured to hold these members. The optical pickup records and/or reproduces an information signal on and/or from an optical recording medium by condensing laser light through the objective lens. The protection member includes a bearing surface to contact a surface of an edge portion of the objective lens not facing the optical recording medium, an aperture to control a diameter of laser light to be incident on the objective lens, and a protection portion protruding toward the optical recording medium with respect to the objective lens. The bearing surface, the aperture, and the protection portion are integrally formed with one another.

Abstract: An optical pickup includes a movable base and an objective lens driving mechanism mounted on the movable base. The objective lens driving mechanism includes a fixed block affixed to the movable base; a movable block having an objective lens and a lens holder holding the objective lens, the movable block moving in focusing, tracking, and tilting directions; supporting springs connecting the fixed block and the movable block; a focusing magnetic circuit including a focusing coil and a focusing magnet; a tracking magnetic circuit including a tracking coil and a tracking magnet; and a tilting magnetic circuit including a tilting coil and a tilting magnet. The lens holder includes a body holding the objective lens, and a thin segment projecting from the body and serving as a dynamic damper that absorbs vibration occurring in the movable block. The tilting coil or the tilting magnet is attached to the thin segment.

Abstract: An optical head for reading an object includes a hollow housing, a light source module, a diffuser structure and a light sensing module. The light source module is fixed in the hollow housing and provides an initial light ray. The diffuser structure is connected the hollow housing, receives the initial light ray, and processes the initial light ray into a uniform light ray for output. The initial light ray is reflected by the diffuser structure multiple times to form the uniform light ray. The light sensing module is fixed in the hollow housing and senses the uniform light ray reflected by the object. An optical axis of the light sensing module is substantially parallel to an axial direction of the diffuser structure.

Abstract: An optical pickup has an objective lens drive device which includes a fixed block fixed to a movement base, a movable block having an objective lens and a lens holder that holds the objective lens, a plurality of support springs that couples the fixed block with the movable block, and a focusing magnetic coil that operates the movable block in a focusing direction. A distance between the fixed block and a recording surface of a disk recording medium is larger than a distance between the movable block and the recording surface. The support springs are inclined with respect to the recording surface. The support springs have a longitudinal direction orthogonal to a direction of a thrust generated at the focusing magnetic circuit to the movable block during a focusing operation.

Abstract: An optical reading system is provided to improve read signal quality with increasing its linear recording density. An optical recording medium in which the distance from a light incident surface to an information recording layer is less than 100 ?m is irradiated with a laser beam through an objective lens and information stored in the information recording layer is read by means of a PRML detection method. At this time, the constraint length n in the PRML detection method is set to an integer which satisfies 0.5×(?/NA)/(LV/f)?1<n<0.5×(?/NA) /(LV/f)+1, wherein ? represents the wavelength of the laser beam, NA represents the numerical aperture of the objective lens, LV represents the linear velocity of the optical recording medium when recording, and f represents a channel bit frequency when recording.

Abstract: An optical pickup device enables prevention of an increase of spherical aberration during tracking without needing any finite optical system. The diameters of parallel light beams (A, B, C) for the next-generation DVDs, DVDs, and CDs are limited to diameters of a, b, c (a>b>c) in accordance with the NA for each type by a light beam limiting element, the diameter of light beam B is limited to the diameter ranges of b to c and d (=0.85×c) to e (d>e>0), the diameter of the light beam C is limited to the diameter ranges of c to d and less than e. They are passed through a phase correcting element (13B) and focused on the corresponding optical recording medium signal planes by means of a common objective lens. The objective lens is so optimized that the wave front aberration to the light beam A is minimum on the signal plane of the next generation DVD.

Abstract: Disclosed is an objective lens used for an optical pickup apparatus to perform writing and/or reading of an optical information recording medium, comprising an antireflective film on a surface of a light source side, wherein a light flux of wavelengths including a wavelength ?1 of 380 nm??1?420 nm and a wavelength ?2 of 630 nm??2?810 nm, is condensed on the medium, a numerical aperture on the light source side with respect to the wavelength ?1 is within a range of 0.8-0.9, and that with respect to the wavelength ?2 is 0.7 or less, and a band of the antireflective film is within a range of 700 nm-800 nm in a state where a reflectance of a light flux perpendicularly entering a central portion of the surface in a wavelength region from 400 nm to 1200 nm is 3.0% or less.

Abstract: An optical pickup apparatus comprises: a base on which a movable optical member is disposed; a metal cover mounted on the base; and an electrical component which is fixed to the base and used to move the optical member. The base is made of resin, and the metal cover touches the electrical component or is connected to the electrical component via a heat-conductive member.

Abstract: A laser beam 32 reflected by an information layer of a multilayer optical disc 26 is reflected and split by reflecting surfaces 31a?, 31b, 31c and 31d to be incident on a photodetector element 36 as laser beams 33, 34 and 35. The laser beam 34 is collected on a light receiving region 38 for RF detection to generate an RF signal. The laser beams 33, 35 are incident on light receiving regions 37a, 37b for focus detection, and a focus error signal is generated by an SSD method. A laser beam 65 reflected by an information layer adjacent to the above information layer partially transmits through the reflecting surface 31a? to be imaged on a light receiving region 66 for tracking detection, and a tracking error signal is generated.

Abstract: In an optical system, reflected light from the disk is diffracted by a hologram optical element, and received by an optical detector. A focusing error signal is detected from ?1st-order diffracted light of the hologram optical element. A tracking error signal by the differential phase method, a tracking error signal by a push-pull method and the data signal recorded on the disk are detected from +1st-order diffracted light of the hologram optical element. A diffraction efficiency of the +1st-order diffracted light is higher than a diffraction efficiency of the ?1st-order diffracted light.

Abstract: There is provided an optical pick-up including first to third light sources respectively emitting first to third light beams, a first coupling lens, and an objective lens formed to converge each of the first, second and third light beams onto the first, second and third optical discs, respectively. The objective lens has a step structure including a plurality of concentrically formed refractive surface zones divided by steps, the step structure having a function of giving, at each step, an optical path length difference of approximately 2?1 to the first light beam. The first coupling lens causes the first light beam to be incident on the objective lens as a converging beam. The objective lens is positioned to satisfy a condition: ?0.35<f2×M2?f1×M1<?0.07??(1).

Abstract: It is to provide a wide-angle optical system for a solid image pickup device that favorably corrects distortion. The imaging lens is a biconvex lens, the object side face is formed into an aspheric shape in which the negative refracting power becomes stronger the farther the imaging lens is from an optical axis in the radial direction, and a condition expressed by the following expression (1) is to be satisfied; 0.8>|r1/r2|?0.5??(1) where, r1: center radius curvature of the object side face of the imaging lens r2: center radius curvature of the image surface side face of the imaging lens.

Abstract: A light source unit comprises a plurality of light sources emitting a plurality of light beams. A plurality of volume hologram elements are provided for the plurality of light sources respectively, each volume hologram element having a plane of incidence of an incoming light beam and a plane of outgoing radiation of a diffracted light beam which are perpendicular to each other, the plurality of volume hologram elements having mutually different Bragg conditions in which an optical intensity of a diffracted light beam is set to a maximum.

Abstract: An optical information recording and reproducing apparatus is provided for recording and/or reproducing information on an optical disc including a recording layer in which information can be recorded at recording positions each located at a different distance from a surface of the optical disc. The optical information recording and reproducing apparatus includes: a light source; and an objective lens which can converge the light flux from the light source onto one of the recording positions at a predetermined depth in the recording layer for recording information on the optical disc. When information to be recorded is recorded on one of the recording positions at a predetermined depth in the recording layer, the optical information recording and reproducing apparatus records information about the predetermined depth on one of the plurality of recording positions at the predetermined depth, with the information to be recorded.

Abstract: An optical pickup device includes a light source unit an optical system which leads a return light beam to a predetermined light-receiving location and includes an object lens focusing each light beam from the light source unit to a recording surface of a corresponding storage medium and a photodetector arranged at the light-receiving location. The light source unit includes a plurality of light sources outputting light beams respectively, the plurality of light sources being arranged in proximity to each other, and a divergence-angle changing unit changing an angle of divergence of a light beam output from at least one of the plurality of light sources.

Abstract: An optical pickup device includes an objective-lens driving mechanism including a lens holder that holds an objective lens configured to focus a light beam emitted from a light source onto an optical disk, a support unit that movably supports the lens holder in a focusing direction parallel to an optical axis of the objective lens and in a tracking direction perpendicular to the optical axis, and magnets that apply predetermined magnetic fields to coils of the lens holder. The optical pickup device further includes a light source holding unit that fixedly holds the light source, and a yoke member attached to a magnet located at a position near the light source. The light source holding unit and the yoke member are thermally conductive metal. The yoke member extends toward the light source and is fixed to the light source holding unit in a thermally conductive manner.

Abstract: Provided is a semiconductor laser driving device which enables to reduce unnecessary power consumption. The laser driving device includes: a laser driving section for supplying a driving current for causing a semiconductor laser to emit light; a temperature detecting section for detecting a temperature of the semiconductor laser; and a voltage control section for supplying a source voltage to the laser driving section while changing a voltage value of the source voltage in accordance with the temperature detected by the temperature detecting section. As a result, unnecessary power consumption can be reduced. An appliance having the aforementioned information laser driving device will make energy savings possible, and further make it possible to suppress temperature increases of the appliance.

Abstract: An objective lens driving device includes an objective lens holder 2 that holds an objective lens 1, plural elastic supporting members 6A through 6F that support the objective lens holder 2, tracking coils 4A and 4B that drive the objective lens holder 2 in the tracking direction, tilting coils 11A and 11B that tilt the objective lens holder 2 with respect to the optical axis passing through the objective lens 1, a tracking control circuit 41 that drives the tracking coils 4A and 4B, and a tilting control circuit 11 that drives the tilting coils 11A and 11B. The tilting control circuit 11 drives the tilting coils 11A and 11B using a signal yielded by multiplying a tracking driving signal from the tracking control circuit 41 by a specific scaling factor K so as to cancel out a tilting force of the objective lens holder 2 generated by the tracking coils 4A and 4B.

Abstract: An optical pickup performing recording, reproduction and deletion of information on or from an optical recording medium. The pickup includes light sources for information recording media using a blue wavelength beam, information recording media of DVD family and information recording media of CD family. A single object lens may be used to condense light from any of the light sources. A single aberration correction device may be disposed in a common light path between each of the light sources and the object lens.

Abstract: A solid immersion lens (SIL) near-field system including: a radially polarized beam generator to generate a radially polarized beam; an SIL; an objective lens to focus the radially polarized beam on a bottom surface of the SIL; and a mask to shield a center portion of the radially polarized beam, the center portion being about an optical axis of the radially polarized beam.

Abstract: An objective lens actuator includes a lens holder which holds an objective lens. A collision preventing portion which prevents collision of the objective lens and an optical disc and a cleaning portion which performs cleaning of the optical disc when the objective lens and the optical disc collide with each other, are set up on the lens holder. It is preferable that the collision preventing portion and the cleaning portion are disposed such that the collision preventing portion is located in an up stream side of a rotating direction of the optical disc and the cleaning portion is located in a down stream side of the rotating direction of the optical disc.

Abstract: An objective lens is moved with a disc irradiated with laser light. A maximum value FEmax and a minimum value FEmin of the focus error signal, and a maximum value FSmax of the amplitude of a focus sum signal are measured. “(FEmax?FEmin)/FSmax” is compared with a determination value to determine the type of a disc.

Abstract: It is intended to provide an optical disk apparatus which detects a light amount greater than zero even when used in conjunction with an optical disk substrate having a large birefringence, so that it is possible to properly read a signal without errors and properly perform optical disk controls. The optical disk apparatus includes: a light source for emitting light; an objective lens for converging the light onto a signal surface of an optical disk; a polarized beam diffraction element for diffracting the light reflected from the optical disk; a photodetector for detecting the light diffracted from the polarized beam diffraction element; and a wavelength plate disposed between the optical disk and the polarized beam diffraction element.

Abstract: The invention permits stable tracking with few control errors, uninfluenced by stray light reflected by signal surfaces other than the signal surface being used for focusing during recording and playback of a multilayer disc. To this end, the optical splitter element of the optical disc device according to the present invention has first areas (21c-24c), which include the location (20) of the optical axis of light incident from the objective lens, and, around the periphery of the first areas, second areas (21a-24a, 21b-24b) positioned at locations displaced from the optical axis. The detection surface (9a) of the photodetector has first detection areas (97, 98) detecting light incident from the first areas and second detection areas (95, 96) detecting light incident from the second areas. The second detection areas are used for detecting tracking error signals.

Abstract: An optical pickup apparatus capable of compensating for a thickness deviation of a high-density optical recording medium is disclosed. The optical pickup apparatus has a light source, a collimator lens, a beamsplitter, and an objective lens system comprising a solid immersion lens which has a planar surface facing the substrate of the optical recording medium. The optical pickup apparatus has a position adjustment unit connected to the light source or the collimated lens, mating the light source or the collimated lens shift according to a focus control signal generated from the focus control unit. Further, a finite optical pickup apparatus in which a collimator lens is not used has a position adjustment unit connected to the light source, making the light source shift according to the focus control signal.