Abstract: Disclosed is an optical disc device that is able to increase accuracy in reproducing information from an optical disc. The optical disc device 10 calculates a focus error signal SFE2 and a sum signal SS1 while reciprocating an objective lens 21 in a focus direction until a distance between a focal point FS and a focal point FM1 becomes close to the depth d of a target position PG at the time of a pull-in operation, and when a trigger signal ST1 generated on the basis of the sum signal SS1 is at low level, starts focus control on the basis of the focus error signal SFE2. Therefore, focus control can start in a state where the focus error signal SFE2 curves in an S shape with sufficient amplitude.

Abstract: [Object] A recoding playback apparatus and an optical disk are provided that allows reduction of a low frequency noise at a time of playback of a super resolution optical disk including small record marks whose size is below the diffractive limitation, to enhance quality of a playback signal. [Means for Solution] The reflective beams from the optical disk are received by dividing into outer portion beams and a center portion beam, and a playback signal is created by combining such beams based on respective different gains. Based on received amounts of light or amounts of low frequency noise in respective light receiving regions, adjustment or determination of gain values is made, or the optical head apparatus is optically adjusted, whereby the low frequency noise is optimally suppressed. Further, a specific region is provided on the optical disk for making the foregoing adjustment.

Abstract: In optical recording and/or reproduction using an SIL optical system that performs a tilt servo using light for recording and/or reproduction, the SIL and an optical recording medium have a high probability of colliding with each other before the tilt servo is started. To prevent the collision, an optical recording/reproduction method performs a gap servo that controls a gap between a surface of an optical recording medium and a bottom surface of an SIL using reflected light that is generated from light traveling from the bottom surface of the SIL and reflecting on the optical recording medium, a focus servo that controls a distance between a focal point of the light and the bottom surface of the SIL, and a tilt servo that controls a tilt of the bottom surface of the SIL relative to the surface of the optical recording medium using the reflected light.

Abstract: A recording apparatus for an optical disk drive is provided. The recording apparatus includes a driver, a servo signal generator, a filter, and a counter. The driver controls a recording speed of the optical disk drive. The servo signal generator generates at least a servo signal. The filter with a specific bandwidth filters the servo signal to generate a filtered servo signal. The counter generate a count value according to the filtered servo signal and instructs the driver to decrease the recording speed of the optical disk drive when the count value exceeds a trigger value, so as to record with the decreased recording speed.

Abstract: An optical system capable of obtaining a high-resolution image using interference and thus capable of providing a stable signal is realized. A particular polarization state of response light emitted from an object is selected, and light in the selected particular polarization state is split into two beams. The split two beams are polarized into two different polarization states. After one of the two beams is subjected to an image inversion, the two beams are condensed such that they interfere with each other. The interfering light is split into a plurality of beams, and each of these beams is detected after they are passed through different polarizing filters. Detected signals are combined together and processed to obtain high-stability amplitude information without being influenced by a phase difference between the two beams.

Abstract: An optical scanning device is adapted for scanning a record carrier having an outer face. The optical scanning device comprises a radiation source for generating a radiation beam, and an objective system having an exit face arranged for evanescent coupling of the radiation beam between the exit face and the outer face and for converging the radiation beam to a focus. A gap servo maintains a distance between the exit face and the outer face at a predetermined gap height. The optical scanning device includes a control unit for setting the predetermined gap height at at least two different values.

Abstract: An object of the invention is to provide an optical element for use in an optical information recording and reproducing device or a like device for recording or reproducing information with respect to an information recording medium using laser light, wherein the optical element is a resin optical element capable of suppressing lowering in transmittance due to deterioration by irradiation of light having a high energy density, and maintaining a high transmittance for a long time. To realize the above object, used is an optical element made of a silicon resin cured material obtained by subjecting a silicon resin composition containing a silsesquioxane compound to a curing treatment.

Abstract: A guide-layer separated optical recording medium includes a guide layer with a guide track formed therein and a plurality of recording layers, these layers being separately deposited from each other. A layer position information region for indicating position information of each of the recording layers, is formed on the guide track within a different range of the guide layer for each of the recording layers. Each of the recording layers includes a preformat region having a predetermined signal written on a record track along the guide track, and the preformat region on each of the recording layers is provided in a region corresponding to the layer position information region. An optical recording medium drive apparatus and a recording layer access method for the guide-layer separated optical recording medium are also provided.

Abstract: There is provided an optical member 1 in which a fixation member 3 supporting the light emitting member 2 is fixed to a housing 5 supporting a light receiving member 4, so as to have clearances between the fixation member 3 and the housing 5, by photocurable resin 6 bridging the clearances, recesses 7 that adjoin positions where the photocurable resin 6 is deposited, that are opened so as to allow casting of light into the recesses 7, and that are to receive portions of the photocurable resin 6 are formed on the housing 5.

Abstract: An optical disc includes a reflective film formed on concave and convex marks after the concave and convex marks are synchronized with the integral multiple of a channel bit length and formed in accordance with modulated main information. Thereafter, continuous or intermittent laser light synchronized with the integral multiple of the channel bit length is irradiated at intervals longer than the longest one of the concave and convex marks in accordance with a spiral track formed in a circumferential direction of the concave and convex marks, whereby an optical characteristic of the reflective film is changed to form a recordable mark and sub-information necessary to reproduce the main information is recorded in a superimposition manner.

Abstract: A control apparatus is provided for controlling an access means for accessing a recording medium containing at least one area so that the access means accesses the at least one area. The apparatus comprises a means for determining whether or not at least one first recorded area storing data is included in the at least one area, and a means for controlling the access means. When it is determined that the at least one first recorded area is included in the at least one area, the control means controls the access means based on a result of accessing the at least one first recorded area.

Abstract: A method of recognizing a track pitch of an optical disk, adapted for an optical disk player, is provided. The method includes the steps of driving an optical pickup head to a predetermined position, so that the optical pickup head and the spindle motor are a predetermined distance apart, reading a data sector address, and recognizing the magnitude of the track pitch of the optical disk according to the value of the data sector address.

Abstract: Provided are a single beam optical pickup device and a disc drive including the optical pickup device. The optical pickup device includes a light controlling device that prevents or limits stray light generated from a medium from being incident on a light sensor. The light controlling device may further include an additional auxiliary light sensor so as to reuse effective light among diffracted light.

Abstract: An optical disc includes tracking polarity information. The optical disc includes a clamping area, a lead-in area, a data area, and burst cutting area (BCA). The BCA is present between the clamping area and the lead-in area and in which information regarding the optical disc is recorded, and the information is read before performing tracking in the data area.

Abstract: An optical information storage medium system is provided. The optical information storage medium system includes an optical pickup, which comprises a photo-detector configured to control light power detected by receiving a portion of light emitted from a light source and obtains an output signal proportional to output light power of the light source from a signal detected by the photo-detector, and a signal processor configured to signal-process the output signal input from the optical pickup. The signal processor includes a sensitivity acquisition unit configured to acquire a sensitivity value of the photo-detector, a gain calculator configured to calculate a target gain value to be used in comparing the sensitivity value of the photo-detector, which is acquired by the sensitivity acquisition unit, with a target sensitivity value to be used by the optical information storage medium system, and a gain adjustment unit.

Abstract: An optical disc device includes a position detector which detects a position of the pickup in accordance with a output signal from the first light receiver of a position sensor which receives light from a encoder board, a rotation position detector which detects a rotation position of the disc in accordance a output signal from the second light receiver which receives a reflected light or a transmitted light of the light irradiated onto the variable area of the disc, and a controller which controls a recording dot marks on a label surface of the disc by driving a feed motor to move the pickup based on the rotation position detected by the rotation position detector and the position detected by the position detector and driving the pickup to control a intensity of the laser light in accordance with the rotation position detected by the rotation position detector.

Abstract: An optical disc apparatus according to the present invention includes: a laser light source for emitting multiple light beams, of which the wavelengths are different from each other and include a first wavelength and a second wavelength that is longer than the first wavelength; an optical system for converging an arbitrarily selected one of the light beams on an optical disc that has a surface and at least one information storage layer; a focus control section for controlling the focus position of the light beam with respect to the optical disc; and a defect detecting section, which senses light reflected from the surface of the optical disc with the focus position of the light beam set on the surface, thereby determining, based on the intensity of the reflected light, whether or not there is a fingerprint on the optical disc.

Abstract: An object of this invention is to improve stability of tracking control and improve recording and reproduction performance. The tracking control device comprises a main push-pull signal generation section, which generates a main push-pull signal based on a signal obtained by photoelectric conversion of return light of the main beam; a microcomputer, which detects an other-layer stray light signal component included in a signal obtained by photoelectric conversion of return light of the sub-beam; a signal correction section, which corrects the signal obtained by photoelectric conversion of the return light of the sub-beam, based on the other-layer stray light signal component; and a sub-push-pull signal generation section, which generates a sub-push-pull signal based on the corrected signal obtained by photoelectric conversion of the return light of the sub-beam.

Abstract: A disclosed image scanning device illuminates a document with a light source, focuses light reflected from the document on an image sensor to obtain one-dimensional images of the document, and obtains a two-dimensional image of the document from the one-dimensional images. The device includes an illumination lens for dividing a light beam emitted from the light source into multiple light beams and a combining unit for combining the multiple light beams on the document. A disclosed image scanning method includes the steps of illuminating a document with a light source; focusing light reflected from the document on an image sensor to obtain one-dimensional images of the document; and obtaining a two-dimensional image of the document from the one-dimensional images. In this method, a light beam from the light source is divided into multiple light beams and the multiple light beams are combined on the document. A disclosed image forming apparatus includes the image scanning device.

Abstract: Provided is an actuator for a pickup, in which end parts of a plurality of suspensions (550A to 550F) of five or more are positioned on a virtual circle (X) formed on a plane by being projected onto the plane including both a focusing direction and a tracking direction. A rolling center (O) defined as a center of the virtual circle (X) is made to coincide with all three, two, or one of a center (Os) of the gravity of a lens holder (600), a center (Os) of the drive force of the lens holder (600), and a center (Os) of the translational force of the suspensions (550A to 550F). Since the rolling center (O) coincides with all three, two, or one of those centers (Os), a rotational moment is not generated on the lens holder (600) and, therefore, generation of unnecessary resonance can be prevented.

Abstract: A method of controlling a tracking error balance in an optical disc apparatus, and the optical disc apparatus are discussed. In an embodiment of the present invention, when a tracking error balance for writing is controlled, a beam power that is appropriate for the writing characteristics of an optical disc is applied. The beam power can be determined based on the Manufacturer Identifier (MID) of the optical disc and writing power information for different MIDs. The beam power can be determined to be a value of 20 to 50% of the prestored writing power for the MID of the optical disc.

Abstract: A reproducing device includes a homodyne detection part that carries out homodyne detection by using reflected light of first light obtained from a recording layer as signal light and using reflected light of second light by a mirror as reference light, a signal reproducing part that obtains a reproduced signal based on the signal light, based on a result of homodyne detection, and a one-axis actuator that drives the mirror. The reproducing device further includes an optical path length servo control part that carries out driving control of the one-axis actuator in such a manner that the optical path length difference between the signal light and the reference light is kept constant, and an offset giving part that gives an offset that reduces or enlarges the amplitude difference of the reproduced signal of marks that are recorded in the recording layer and have sizes different from each other.

Abstract: An optical head device has at least one upward-reflecting mirror, objective lenses, an objective lens actuator, and a moving mechanism. The upward-reflecting mirror receives an incident luminous flux having a wavelength emitted from a semiconductor, and changes its direction. The objective lenses having mutually different numerical apertures condense the luminous flux whose direction has been changed by the upward-reflecting mirror to radiate a condensed luminous flux onto an information recording medium. The objective lens actuator moves the objective lenses in the focus direction of the information recording medium so that the luminous flux incident on the information recording medium attains a focused state. The moving mechanism moves the upward-reflecting mirror so that the luminous flux is incident on the information recording medium via any one of the objective lenses.

Abstract: This optical disk device includes a pickup, an offsetting means, a focus servo means, a layer jump means, and a shift means. The pickup irradiates laser light upon an optical disk having a plurality of recording layers via a correction lens and an objective lens, and detects light reflected back from the optical disk. The offsetting means generates a focus error (FE) signal on the basis of the reflected light, and applies an offset voltage to the focus error signal. The focus servo means performs focusing servo on the basis of the FE signal. And, before layer jumping is executed by the layer jump means, the focus servo means displaces the correction lens to an intermediate position after having adjusted the offset voltage to a balance value. Then the layer jump means performs layer jumping.

Abstract: An optical pickup includes a light emitting component, an optical component and a base component. The light emitting component has a laser diode, a package and a holder. The package has a positioning recess formed in an outer peripheral face of the package. The holder holds the package in a fitting hole of the holder. The holder has a protrusion component that is formed in an inner peripheral face of the fitting hole of the holder and is fitted to the positioning recess of the package, and a guide component that extends from the protrusion component by a first specific height beyond an end face of the holder. The protrusion component has a width in a peripheral direction of the fitting hole that is at least equal to a width of the positioning recess of the package in a peripheral direction of the package.

Abstract: In an optical disk apparatus, an optical pickup includes an actuator for driving an object lens, and a sensed signal output part for making it possible to generate a tracking error signal and a lens error signal by addition/subtraction, and a signal processor includes a servo signal generator for generating a tracking error signal and a lens error signal on the basis of a signal supplied from the sensed signal output part, and a tracking offset correction quantity signal generator supplied with the lens error signal to output a tracking offset correction quantity signal. DC (direct current) offset correction is conducted by conducting addition/subtraction between the tracking error signal and both the lens error signal and the tracking offset correction quantity signal.

Abstract: A light beam emitted from a laser source is divided into a first light beam and a second light beam. An optical divider is further provided to separate a combined light beam of the first and second light beams into a first light bundle near the optical axis and a second light bundle in the edge portion and to diverge the first and second light bundles so that the first and second light bundles are individually detected by plural detectors. The first light beam is signal light focused on an optical information recording medium by an objective lens and reflected off the medium, and the second light beam is reference light not focused on the optical information recording medium. A focus error signal is then detected for the first light bundle for compensating focus error.

Abstract: To provide an optical disk device, an optical disk control method and an integrated circuit, which are capable of writing a recordable mark by changing the reflectance ratio of a reflective film formed on concave-convex pits without using an industrial special device or a high-power laser light source. A data reproduction controller (103) sets a first rotation speed in a disk rotation speed switching unit (108) and a first laser power in a laser power switching unit (107) when reproducing the concave-convex pits. When writing the recordable mark, a mark recording controller (104) sets in the disk rotation speed switching unit (108) a second rotation speed that is slower than the first rotation speed and the lowest rotation speed at which the concave-convex pits can be reproduced, and sets a second laser power greater than the first laser power in the laser power switching unit (107) in accordance with the emission timing.

Abstract: An optical disk apparatus according to the present invention includes: a controller 111, which receives an instruction that a layer-to-layer jump be performed from a current layer to a target layer; a layer-to-layer jump control section 146, which adjusts a spherical aberration correction value to the target layer and then gets the layer-to-layer jump attempted; a decision section 146 for determining whether the layer-to-layer jump has been carried out successfully; and a layer determining section 146 for determining, if the focus position has been set on a non-target storage layer as a result of the layer-to-layer jump, where the non-target storage layer is located in the optical disk. The layer-to-layer jump control section 146 shifts the focus position of the light beam from that non-target storage layer to the target layer by reference to information indicating which of the multiple storage layers the non-target storage layer is.

Abstract: To provide an optical head to produce good servo and read signals by reducing the influence of interference by light reflected from a non-read layer of a multilayer optical disc. The head includes: a first optical system for converging light from a light source on a first or second storage layer; a second optical system for receiving and transmitting light reflected from the first layer and stray light reflected from the second layer when the light is converged on the first layer; a photodetector; and a calculator. The photosensitive areas of the photodetector output signals representing intensities of the light incident there through the second system. The reflected and stray light incident on the second system interfere with each other, and the first and second groups of areas are arranged so as to be equally affected by a variation in intensity caused by the interference.

Abstract: In an optical pick-up used in common with DVD/CD and BD, when the thickness is intended to be reduced by mounting a total reflection mirror, a cavity for passing through a laser light is necessary and, since this decreases the degree of freedom for arranging tracking coils and magnets and secondary resonance caused by a magnetic thrust in the tracking direction tends to be generated, an improvement therefor is necessary. In a lens coil holder of the optical pick-up having an objective lens and tracking coil mounted thereon each of the coils is arranged such that the thrust relative to the vertical center of the suspension wires that support the lens coil holder is well balanced. For example, most of the portion of the tracking coils is situated at one height relative to the suspension wire and the tilt coil is situated at the other remaining height.

Abstract: An integrated circuit includes a focus control section configured to perform focus control to generate a drive signal for the focus direction displacement section based on a focus error signal, a focus control error determination section configured to determine whether there is a focus control error or not, and a memory section configured to store error-time control signals which are used when there is a focus control error and correspond to a plurality of rotation angles. The focus control section stops the focus control and generates the drive signal for the focus direction displacement section, according to a rotation angle, based on the error-time control signals stored in the memory section at a radial position where it is determined by the focus control error determination section that there is a focus control error.

Abstract: An apparatus for compensating for a defect of a storage medium of an optical driving includes a memory to store sample values of a servo driving signal during at least one track sampled by a first signal and cycle information about the first signal; a servo driving signal estimator to estimate a servo driving signal during at least one next track using the sample values, the cycle information about the first signal, and cycle information based on a second signal; and a transmitter to transmit the servo driving signal estimated by the servo driving signal estimator to a servo driver of the optical driving device during a defect section of the storage medium; wherein the first signal is synchronized with a radial direction of the storage medium; and the second signal has a frequency higher than the first signal.

Abstract: In servo control of actuators of an optical disc unit, a gain margin is secured by measuring a mean current or mean voltage applied to each of a focus actuator and a tracking actuator, estimating a displacement quantity of each of the actuators from the measurement values, changing the frequency characteristic or overall servo loop characteristic of a focus servo filter and a tracking servo filter respectively by switching ON/OFF a notch filter according to a displacement condition of the corresponding actuator, and switching control operation between stages of servo control characteristic of each of the focus servo filter and tracking servo filter. The optical disc unit can achieve a stable servo control of the actuators thereof without performing disturbance injection or taking measurement of the disturbance. Thus, the optical disc unit can ensure stable operations.

Abstract: An optical pick-up which permits the relative position of a diffracting optical element and a photodetector to be adjusted by feedback control with signals which are generated when more than one kind of diffracted light differing in order is received, the diffracted light occurring as the reflected light from the optical disc is divided and diffracted by the diffracting optical element having multiple regions. The photodetector which detects the light beam passing through the central region of the diffracting optical element and generates RF signals is juxtaposed with sub-photodetectors, so that they receive reflected stray light from out-of-focus layers and perform computation to calculate the reflected stray light component which the RF signal detector receives, thereby detecting only the component of signals of the reflected light from a target layer.

Abstract: An optical disk apparatus includes an optical pickup and a signal processor. The optical pickup includes an actuator for driving an objective lens, and a detected light intensity signal output part for outputting a detected light intensity signal to the processor. The signal processor includes a servo signal generator for generating a main push-pull signal and a sub push-pull signal on the basis of the detected light intensity signal supplied from the detected light intensity signal output part, a signal generator for generating a differential push-pull signal and a lens error signal by conducting addition/subtraction on the main push-pull signal and the sub push-pull signal, and a tracking offset correction signal generator which is input with the lens error signal to output a tracking offset correction signal. The differential push-pull signal correction is conducted by conducting addition/subtraction between the differential push-pull signal and the tracking offset correction signal.

Abstract: The present invention relates to a method of reducing the wear of a tip of a probe when the tip is in contact with a surface of a substrate and when the probe is mounted on a support structure. A method is provided where a load force is applied to the probe, thereby causing the tip to be maintained substantially in contact with the substrate surface and a modulation step where the e magnitude of the load force is modulated at a modulation frequency. The modulation frequency is selected to be greater than a fundamental vibration frequency of the support structure on which the probe is mounted.

Abstract: A focusing servo device, an optical disc recording/reproducing device and a focus-searching method are provided for making a focus of an energy beam emitted by a pick-up unit to fall in an accessible range of a data layer of a disc. The method comprises the following steps: recording the deviation of the focal point during each predetermined period when the focal point of the energy beam is fallen in the accessible range such that the optical disc recording/reproducing device is operated in a feedback control mode; determining a focus-searching range based on the recorded deviation of the focal point; and moving the focal point in the focus-searching range to make the focal point to fall in the accessible range when the focal point of the energy beam is fallen out of the accessible range such that the optical disc recording/reproducing device is operated in a focus-searching mode.

Abstract: A beam irradiation device includes a light source for emitting laser light, an actuator for displacing a propagation direction of the laser light in accordance with a control signal, and a scan expansion lens for increasing a swing width of the laser light to be generated by the actuator. A spectral element is arranged between the actuator and the scan expansion lens. The spectral element allows at least a part of the laser light to be incident from the actuator to transmit, and reflects at least a part of the laser light to be incident from the scan expansion lens. The beam irradiation device further includes a light detector for receiving the laser light to be reflected on the spectral element to output an electrical signal.

Abstract: A system and method for labeling with a laser an optical disc having a plurality of markable locations. Signals indicative of a focus of the laser to the disc are measured, while rotating the disc at a constant angular velocity. Focus positions for designated ones of the locations to be marked on the disk are determined from the measured signals. The designated locations are marked with the laser while rotating the disc at a constant linear velocity and positioning the laser at the corresponding focus position. For at least some radial positions of the laser, an angular velocity corresponding to the constant linear velocity is less than the constant angular velocity.

Abstract: An object of the present invention is to reduce the influence of a stray light incident on a light receiving device by reflection of an unnecessary diffraction light not contributing to write or read on a disc surface at write or read of an optical disc having a large surface reflectivity with respect to an information recording surface. A position in which a diffraction light with an n-order in an advancing path and the n-order in a returning path, reflected on the information recording surface of a first information recording medium, is focused by a condensing lens is different from a position in which a diffraction light different from the n-order diffraction light in at least one of the advancing path and the returning path, reflected on a surface of the first information recording medium, is focused by the condensing lens.

Abstract: A read-only optical disc medium is disclosed. The disc medium includes: an information recording area in which information is recorded by means of an embossed pit array formed in a convexo-concave shape having a reflective layer deposited thereon; a test writing area which is used for test write recording of a mark formed by dissipating or decreasing the reflective layer; and an additional write area in which a record data string is formed of a mark by dissipating or decreasing the reflective layer under a recording condition decided in accordance with a result of test write recording performed in the test writing area.

Abstract: The invention relates to a method for reading a Fourier hologram recorded on a holographic storage medium with a holographic storage system. The method comprises the steps of: —calculating a characteristic value from a detected image of a reconstructed Fourier hologram in at least two relative positions of a reference beam and said storage medium, each of the characteristic values being indicative of a misalignment of the reference beam and said storage medium at the respective relative position, —calculating a servo value from the measured characteristic values, —determining an aligned relative position of said reference beam and said storage medium by means of a predetermined servo function using the calculated servo value, —setting the relative position of the reference beam and said storage medium to said aligned relative position, and—detecting an image at said aligned relative position.

Abstract: An optical pickup actuator independently drivable in focusing, tilting and tracking directions. The optical pickup includes a lens holder movably installed on a base, and mounted with an objective lens for transmitting an incident light to an optical information recording medium; and a magnetic circuit to independently driving the lens holder in the focusing, tilting and tracking directions. The magnetic circuit includes opposing magnets; a focusing coil and tilting coils interposed between the magnets, mounted inside the lens holder, and wound around respective axes parallel to the focusing direction; and a plurality of tracking coils mounted outside the lens holder, interposed between the magnets and wound around respective axes transverse to the focusing direction. The magnetic fields of the magnets are guided by outer yokes partially encompassing the magnets and inner yokes positioned within the focusing coil and the tilting coils.

Abstract: An optical disc drive apparatus includes: a first optical pickup and a second optical pickup which record data on an optical disc and reproduce data recorded on the optical disc; a slide mechanism which has the first and second optical pickups mounted thereon to slide the first and second optical pickups in a radial direction of the optical disc; a seek command receiver which receives a seek command; a first optical pickup controller which causes the first optical pickup to perform a search on the basis of the seek command received by the seek command receiver; a slide mechanism controller which controls the slide mechanism on the basis of the seek command received by the seek command receiver; and a second optical pickup controller which turns off a tracking servo of the second optical pickup when the first and second optical pickups are slid by the slide mechanism.

Abstract: A recording apparatus for performing information recording using formation of marks by focusing a first light with an objective lens at a given position in a recording layer included in an optical disc recording medium, includes: a rotation driving unit; a focus servo control unit for condensing a second light on a reflection film and for controlling a position of the objective lens; a recording position setting unit for setting an information recording position of the first light in a focus direction; a tracking servo control unit for controlling a position of the objective lens; an eccentricity amount estimating unit for estimating an eccentricity amount of the optical disc recording medium; and an eccentricity estimation amount acquisition control unit for acquiring an eccentricity estimation amount for each rotation angle within one revolution of the disc.

Abstract: An optical head device and an optical disc apparatus of a simple structure capable of canceling an offset in a tracking error signal caused when an objective lens shifts; in the optical head device, a polarizing hologram 104 has first diffraction areas 112 and 113 including a whole of an area irradiated with overlap of a zeroth-order beam of reflection light from an optical disc 1 and positive/negative first-order beams of the reflection light, and a second diffraction area 111 including an area irradiated with the zeroth-order beam of the reflection light and not irradiated with the positive/negative first-order beams of the reflection light without including the first diffraction area; and a photodetector 109 has a first light receiving section 131 for receiving a first light beam which is a zeroth-order beam of diffraction light generated by the polarizing hologram 104, a second light receiving section for receiving a second light beam which is a positive first-order beam of the diffraction light generated

Abstract: An optical drive apparatus that reproduces an optical disk having a land and a groove, the optical drive apparatus including a first tracking-error-signal generating unit that generates a first tracking error signal by using a DPD method, a second tracking-error-signal generating unit that generates a second tracking error signal by using a DPP method, a tracking servo unit that controls the optical system, and a determining unit that determines that an irradiation point of an optical beam is in a non-recorded area. The tracking servo unit switches over to a control based on the second tracking error signal in response to a result of determination by the determining unit during performing a control based on the first tracking error signal.

Abstract: A metallic wave guide and a light delivery module are provided. The metallic waveguide includes a metal body formed of a conductive metal and having an aperture formed therethrough, the aperture having input and output ends. The aperture has a bent portion for changing a light traveling direction between the input and output ends, and a tapered portion between the bent portion and the output end. The tapered portion has a width that is gradually reduced toward the output end, and the aperture is formed in a C-shape by a ridge formed on an inner surface of the metal body.

Abstract: An optical unit includes an optical system for shining a laser beam on an optical recording medium having a recording layer and a focus control reference surface. The optical system is composed of an objective lens for focusing a recording/reproducing beam emitting from a first light source in the recording layer and focusing a focus control beam emitted from a second light source on the focus control reference surface, a first lens system disposed along an optical path of the recording/reproducing beam and capable of discretely varying a focus position of the recording/reproducing beam in a direction of a thickness of the recording layer, and a second lens system disposed along an optical path common to the recording/reproducing beam and the focus control beam and capable of continuously varying focus positions of the recording/reproducing beam and the focus control beam in a direction of a thickness of the recording layer.