Abstract: A projection device and a projection method, a projection module, an electronic device, and a program that correct a misalignment of an optical axis are disclosed. Test emission is performed of a laser beam that is a light source in a projector, and a position of the optical axis of the laser beam is obtained from a ratio of an amount of light detected by a photodetector divided into a plurality of areas that is a two-dimensional plane perpendicular to the optical axis. The misalignment of the optical axis is obtained on the basis of information regarding a position of the optical axis of each of R, G, and B, a correction coefficient is calculated for correcting a shift of a pixel position on a projection image projected on a screen, and a pixel position to be projected is corrected with the correction coefficient and projected with RGB misalignment correction.

Abstract: A phase distribution calculation method includes: moving a focal position of an optical system to a plurality of positions within a phase object, the plurality of positions being different from each other in an optical axis direction of the optical system, and acquiring an image via the optical system in each of the plurality of positions; calculating a first phase distribution of a three-dimensional region that corresponds to a plurality of images acquired in the plurality of positions, in accordance with the plurality of images; and correcting the first phase distribution in accordance with a change in the optical axis direction in a region of interest specified in the three-dimensional region.

Abstract: A recording apparatus includes a recording unit that performs a recording operation to each layer by performing laser light illumination to a recording medium which has (n+1) or more layers as a recording layer and in which a test writing area of each layer is formed between at least n consecutive layers and at a position in which the test writing areas are not overlapped with each other when seen from a laser light incident surface side, and a controller that sets the n consecutive layers to be a recording target layer in the recording operation including a test writing for laser power adjustment and causes the recording unit to execute the recording operation to the n recording target layers, wherein n?2.

Abstract: A calculating method for calculating structural data of a two-level diffractive optical element configured to form a set of light intensity distributions point-symmetrical with respect to an axis on an image plane utilizing an iterative Fourier transform algorithm executed by a computer includes calculating a light intensity distribution and a phase distribution of a plane of the two-level diffractive optical element which has a Fourier transform relationship with the image plane by performing an inverse Fourier transform for a light intensity that is made by removing one of the set of light intensity distributions from the set of light intensity distributions, and calculating structural data of the diffractive optical element based upon the light intensity distribution and the phase distribution which have been calculated.

Abstract: An exemplary optical pickup comprises: a light source with first and second emission points; an optical branching element which branches light emitted from the first emission point into multiple light beams including a first main beam and first sub-beams and which also branches light emitted from the second emission point into multiple light beams including a second main beam and second sub-beams; an optical system which condenses the multiple light beams produced by the optical branching element onto an optical storage medium, thereby making the first and second main beams form a write light beam spot and a read light beam spot, respectively, on a target recording track on the storage medium and making the first and second sub-beams form reference light beam spots and other light beam spots somewhere on the storage medium other than the target recording track.

Abstract: In one embodiment, the optical read/write apparatus includes a plurality of optical pickups arranged to cross tracks of an optical storage medium and a control section. On finding the data that has been written by any of those optical pickups inaccurate or on detecting any defect at a location where data is going to be written by any of the optical pickups, the control section instructs another one of the optical pickups to write that data on a different track from a track on which the data should have been written.

Abstract: The apparatus includes a pickup for reading data from a super-resolution optical disc, the pickup comprising a laser for generating a main beam, a first and a second satellite beam, the two satellite beams each having a radial offset with regard to the main beam, a third satellite beam following the first satellite beam, having the same radial offset as the first satellite beam, and a fourth satellite beam following the second satellite beam, having the same radial offset as the second satellite beam, for providing a crosstalk correction of the HF data signal. The track pitch between adjacent tracks of the optical disc is particularly below the diffraction limit of the pickup, and the light intensity of each of the first and second satellite beams and of the main beam is sufficient to provide a super-resolution effect on the optical disc and the light intensity of each of the third and fourth satellite beams is not sufficient to provide the super-resolution effect.

Abstract: Systems and methods for data storage on an optical medium having a plurality of tracks include splitting a light beam into a higher power main beam and at least one lower power side beam that form corresponding spots spaced along a selected one of the plurality of tracks and selectively positioning and aligning the beams/spots along the selected one of the plurality of tracks using the higher power main beam to write data while reading previously written data using the at least one lower power side beam. The systems and methods may include correlating the read signal with a time-shifted write signal to provide a direct read after write capability to verify data written to the optical medium. In one embodiment, an optical tape drive includes an optical pickup unit (OPU) that generates a lower power satellite beam to read data directly after writing by a higher power main beam.

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 information recording method includes emitting light having a wavelength ?1 from a first light source with a pulse width of time tw1 or more and power P1, emitting light having a wavelength ?2 from a second light source with a pulse width of time tw2, a repetition interval T, and power P2, and performing information recording by simultaneously irradiating an identical part of a recording medium with the light from the first light source and the light from the second light source, in which the wavelength ?1 and the wavelength ?2 satisfy ?1>500 nm>?2 and ?0 which is expressed as 1/?1+1/?2=1/?0 satisfies a relationship of ?0<300 nm, and emission of the first light source and emission of the second light source satisfy relationships of tw2<tw1, T<tw1, and P2>P1.

Abstract: A recording and reproducing unit includes: a first optical head having at least one route of laser beam irradiation system that irradiates an optical disc recording medium with a laser beam; a second optical head having plural routes of laser beam irradiation systems that irradiate the optical disc recording medium with laser beams; and a control part that performs control of, while allowing the laser beam irradiation system that the first optical head has to execute recording of information in the optical disc recording medium, allowing the plural laser beam irradiation systems that the second optical head has to execute simultaneous reproducing of the information recorded in the optical disc recording medium.

Abstract: An optical information recording medium includes a recording layer in which a track is formed, the track having recording marks linearly arranged thereon. Each recording mark has a dimension corresponding to a reference mark length, which serves as a reference, in a track direction along which the track extends, the dimension being smaller than dimensions of the recording mark in two directions perpendicular to the track direction.

Abstract: Provided is a light-spot-position control apparatus including: a first-light-source; a second-light-source; a beam-splitter splitting a beam of the second-light-source into m beams; an optical-system allowing a first-beam of the first-light-source and the m beams to irradiate a disk-shaped recording-medium, where grooves and lands are alternately formed with an equal radial width to form the grooves in spiral/concentric shape through common-objective-lens, the optical-system allowing the three beams to irradiate the recording-medium so that an interval of m beam-spots is 1/m of track pitch; a tracking-control-mechanism tracking-controlling the beam by changing a relationship between the optical-axis and the recording-medium; a light-receiving unit individually receiving the m beams; an error-signal generator generating error-signals representing radial-position-errors of the spot-positions of the m beams with respect to the tracks based on received signals; an error-signal selector selecting at least one erro

Abstract: A recording device includes a plurality of channels configured to record data to an optical recording medium, a reception unit configured to receive data transmitted from an external device, a storage unit configured to temporarily store the data that is received by the reception unit, and a distribution control unit configured to read the data that is stored in the storage unit and distribute the data by a block unit to the plurality of channels based on transfer time of the data and recording time to the optical recording medium so that record processing of the plurality of channels are simultaneously ended.

Abstract: An optical information recording method includes emitting light having a wavelength ?1 from a first light source with a pulse width of time tw1 or more and power P1, emitting light having a wavelength ?2 from a second light source with a pulse width of time tw2, a repetition interval T, and power P2, and performing information recording by simultaneously irradiating an identical part of a recording medium with the light from the first light source and the light from the second light source, in which the wavelength ?1 and the wavelength ?2 satisfy ?1>500 nm>?2 and ?0 which is expressed as 1/?1+1/?2=1/?0 satisfies a relationship of ?0<300 nm, and emission of the first light source and emission of the second light source satisfy relationships of tw2<tw1, T<tw1, and P2>P1.

Abstract: A multilayer optical disk apparatus comprises an optical pickup that emits N (N represents an integer of two or more) laser beams of the same wavelength. The optical pickup emits the N laser beams at the same time, focuses the N laser beams on a first recording layer group alternately configured by N recording layers of the multilayer optical disk and performs a recording operation on the N recording layers at the same time. When changing the recording layers the optical pickup focuses the N laser beams on a second recording layer group configured by recording layers adjacent to the respective recording layers configuring the first recording layer group and performs a recording operation on the N recording layers at the same time.

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: A write analysis system is described for an optical drive, where the optical drive includes an optical storage medium. The write analysis system includes a filter that receives a reflected signal that is based on a reflection of a diffracted laser beam. The reflection of the diffracted laser beam includes a reflection of a first write signal. The filter generates a filtered signal by filtering the first write signal from the diffracted laser beam. The system also includes a read-back module that receives the filtered signal and that compares the filtered signal to a second write signal that was written to the optical storage medium prior to the first write signal.

Abstract: An optical-pickup apparatus comprising: a laser-light source; a diffraction grating including first-and-second regions of periodic structures different in phase from each other and a third region whose periodic structure is different in phase from the first-and-second regions; an objective lens focusing main-and-sub-luminous fluxes generated by the diffraction grating on the same optical-disc track; and a photodetector to receive reflected light of the main-and-sub-luminous fluxes from an optical disc and output a detection signal for generating main-and-sub-push-pull signals, a relationship between an incident light width in the objective lens corresponding to the third region and pupil diameters of the objective lens corresponding to first-and-second wavelengths of laser lights being adjusted so that a ratio of minimum value to maximum value of a differential-push-pull-signal is at substantially 50% or more and a ratio of sub-push-pull-signal level to main-push-pull-signal level is at substantially 15% or m

Abstract: A recording apparatus includes a first light source irradiating first laser light, a second light source irradiating second laser light, an optical spatial modulating unit applying information to the first laser light, and an objective lens collecting the first laser light and the second laser light at different positions on the same optical axis. A hologram recording operation uses a first optical path and a second optical path. The information light is conducted to the objective lens along the first optical path. The reference light is conducted to the objective lens along the second optical path. At the same time, an address/servo control operation is carried out by employing a third optical path along which the second laser light is conducted to the objective lens. The DVD recording operation uses the second optical path. The CD recording operation uses the third optical path.

Abstract: A recording/reproducing apparatus (100) is provided with comprising: recording devices (131a-131e) for recording record signals (WS1-WS5) in parallel and in synchronization with a record clock; a signal generating device (143) for generating record signals such that a reproduction clock synchronized with the record clock can be generated on the basis of the reproduced record signals, if the plurality of record signals are reproduced in parallel; reproducing devices (131a-131e) for reproducing the record signals in parallel; and a clock generating device (154) for generating a reproduction clock.

Abstract: A recording apparatus includes: a recording device for recording data onto each of a plurality of types of recording media by irradiating a light beam corresponding to each of the types of recording media; a diffracting device disposed on an optical path of the light beam from the recording device to the recording medium, for generating a main beam and a plurality of sub beams by diffracting the optical beam, the main beam recording data and performing a tracking process, the sub beams performing the tracking process, an amplitude of a tracking signal generated by each or one portion of the sub beams and by the main beam being maximum; a controlling device for controlling the diffracting device to adjust a position on which each of the plurality of sub beams is focused, in accordance with the type of the recording medium; and a tracking device.

Abstract: A first recording layer for recording information of an optical disk and a second recording layer of the optical disk on which a visible image can be recorded are disposed at an interval of 0.5 mm or more. Thus, even when a high power laser is used on one of the layers, data on the other layer will not be destroyed.

Abstract: A holographic optical information playback apparatus for playing information that is recorded on a recording medium in a form of interference fringes is provided with a two-dimensional photoreceptor array which receives a two-dimensional array of light spots that is diffracted at the recording medium due to application of reference light onto the medium, and outputs a playback signal including information recorded on the recording medium. The two-dimensional photoreceptor array has a photoreceptor section in which plural photoreceptor cells for detecting the intensities of received lights are arranged so that a photoreceptive area corresponding to the light spot array is formed, and assigns plural photoreceptor cells are assigned to each light spot in the light spot array according to the irradiation position of the light spot array, whereby the light intensity of one light sport is detected using the output signals from the plural photoreceptor cells.

Abstract: A recording apparatus for recording record data onto a recording medium on which a plurality of recording layers are formed in a thickness direction, is provided with: a recording device for recording the record data into each of the plurality of recording layers by emitting each of a plurality of recording light beams to be focused on a corresponding one of the plurality of recording layers; a calculating device for calculating a leaked beam feature of another recording light beam, which is emitted to be focused on another recording layer other than one recording layer of the plurality of recording layers, leaking to the one recording layer; and an adjusting device for adjusting an emission condition of at least one of the plurality of recording light beams, on the basis of the calculated leaked beam feature.

Abstract: A disc-shaped information recording medium includes a first recording layer (L0 layer) having (I) a first trial write area (101P-1) for trial write of first trial write information for calibration of the laser beam along the first track path (TP1) from the inner circumference toward the outer circumference and (II) a first recording area for recording the first recording information along a first track path (TP1), in this order from the inner circumference side. Furthermore, the disc-shaped information recording medium includes a second recording layer (L1 layer) having (I) a second trial write area (101P-2) for trial write of second trial write information for calibration of the laser beam along the second track path (TP2) from the outer circumference toward the inner circumference and (II) a second recording area for recording the second recording information along a second track path (TP2), in this order from the inner circumference side.

Abstract: A data reproducing method reproducing data recorded in a super resolution information storage medium in a form of marks having magnitudes less than a resolving power of an incident light beam, and an apparatus thereof. The data reproducing method includes irradiating a first beam having a resolving power causing a super resolution phenomenon and a second beam having a resolving power not causing a super resolution phenomenon into different places on the information storage medium, detecting a first reproduction signal based on the first beam and a second reproduction signal based on the second beam, and compensating for and calculating a temporal delay between the first reproduction signal and the second reproduction signal. Therefore, a signal reflected from a peripheral area of a reproduction beam spot other than a super resolution area can be excluded, thereby improving reproduction signal characteristics.

Abstract: An optical head device 201 includes a light source 1, an objective lens group 13, a two-dimensional actuator 15, spherical aberration adding means 9, 10, and 16, a hologram element 17 for splitting the light beam from the optical disk 14 into a plurality of split light beams, and a photodetector 22 which includes at least one photoreceptor including a plurality of split light receiving areas and outputs an electric signal corresponding to the light amount of a split light beam entering each of the plurality of split light receiving areas or an electric signal corresponding to a combination of the light amount of split light beams entering the corresponding split light receiving areas, and the plurality of split light beams split by the hologram element 17 include one circular ray U1 and at least two annular rays U2 and U3.

Abstract: The invention relates to a diffraction grating, a light-receiving element, and an optical head and an optical recording/reproducing apparatus utilizing them and provides a diffraction grating and a light-receiving element capable of detecting a signal of high quality and an optical head and an optical recording/reproducing apparatus utilizing them. A diffraction grating includes a diffracting region which is formed only on a light exit surface and which diffracts and separates first laser light or second laser light emitted by a two-wavelength semiconductor laser to generate a main beam and positive and negative first order sub beams. The depth of concavity formed on the diffracting region is 220 nm. The irregularities are formed such that the pitch length thereof is 22 ?m and such that a convexity thereof has a width of 17.6 ?m. The ratio of the width of the convexity to the pitch length of the irregularities is 0.8.

Abstract: The invention relates to an optical pickup for an optical recording medium, an electrically controlled diffraction grating suitable for use in such a pickup, and to an apparatus for reading from and/or writing to optical recording media using such an optical pickup or diffraction grating. According to the invention, an optical pickup for optical recording media having two or more data tracks, with a light source for emitting a light beam for reading from and/or writing to an optical recording medium, includes an electrically controlled diffraction grating, which is switchable between at least two states for generating one or more light beams from the light beam emitted by the light source for reading from and/or writing to one or more of the data tracks.

Abstract: A multi-channel optical recording and/or reproducing apparatus includes an optical pickup including a plurality of light sources, the optical pickup being adapted to emit a plurality of light beams to a corresponding plurality of tracks of an information storage medium and to detect a plurality of light beams reflected by the corresponding plurality of tracks of the information storage medium; and a control signal generating unit to generate a control signal which equalizes and controls aberrations occurring due to a wavelength difference between the plurality of light sources, a displacement difference on an optical axis between the light sources, or a distance between the light sources, based on detection signals generated according to the plurality of reflected light beams.

Abstract: A method and miniaturizable device is described to read/write information to an optical storage medium (11). A device comprises one or more light sources (12) bounded up with an access unit (10) which is arranged to be controllable to a position, in which light beams (21, 22) are transmitted transversal towards an optical storage medium, and reflected light beams (33) are analysed by a detector element (18, 26) which further informs the access unit whether to move or stand still to keep light beams in focus and on track. A device according to the invention is possible to implement in a small size and low weight due to reduced component count and thin access unit geometries. A communication device (80) according to the invention may be implemented to fulfil a crucial need for ultraminiature range of communication devices.

Abstract: The present invention provides a two-dimensional encoded optical storage medium (12) comprising at least one alignment pattern (14) for aligning a spot array (16) intended to read out the optical storage medium (12). Furthermore, the present invention is directed to a method and a device for reading out a two-dimensional encoded optical storage medium (12) having at least one alignment pattern (14) comprising a plurality of bit rows (R1, R2, R3, R4, R5, R6, R7, R8), wherein at least one bit row (R2, R3, R4, R6, R7, R8) of said alignment pattern (14) is empty.

Abstract: Disclosed here is an apparatus and method for realizing write/read of mass information by reducing cross-talk components that are apt to increase in narrow tracks when various disturbances and variations are recognized. In order to achieve the above object, the apparatus is provided with a plurality of equalizers for correcting frequency characteristics of signals reproduced from a plurality of spots, then outputs from those equalizers are subjected to a computing process to correct tap coefficients of the equalizers sequentially so as to minimize the influence of the subject cross-talk, thereby realizing stable reduction of the cross-talk components.

Abstract: Methods and apparatuses for determining a relationship between a main beam and a side beam are provided. One proposed method includes: measuring reflected light of the side beam under a first laser power to generate a first value; measuring reflected light of the main beam under the first laser power to generate a second value; measuring reflected light of the side beam under a second laser power to generate a third value; measuring reflected light of the main beam under the second laser power to generate a fourth value; and determining a ratio of the main beam to the side beam according to the first, second, third, and fourth values. Once the ratio ? of the main beam to the side beam is determined, at least one servo control signal can be generated accordingly.

Abstract: It is an object to provide a recorded information reproducing apparatus that allows to eliminate crosstalk from an adjacent track correctly, even from a recording medium having both a recorded area in which information data are recorded and an unrecorded area. In order to detect a crosstalk component from an adjacent track based on a correlation between a main read signal read from a main track and a sub read signal read from an adjacent track, the relative phase between the sub read signal and the main read signal is shifted.

Abstract: In fabricating a monochromic and highly coherent light source, no single crystalline bulk semiconductor is used, but two different kinds of transparent substances are alternately stacked over each other to constitute a periodic structure in ½ of the intended wavelength. At least one of the two kinds of transparent substances is controllable in electric conductivity, and the structure is such that inside a medium consisting of this kind of transparent substance light-emitting semiconductor particulates are embedded. Accordingly, a light-emitting device has this structure, which makes possible control of the center wavelength of light emission, the width of wavelength distribution and coherence by adjusting the geometrical parameters of the device without having to alter the kind of material use.

Abstract: An optical pickup apparatus for compensating for the deviation in the thickness of the optical disk and method therefor.

Abstract: A plurality of optical heads each of which comprises an independent light source and optical system are provided on the same side with respect to a recording medium having a plurality of recording layers. Alternatively, with respect to at least one light source in an optical head having a single objective lens and a plurality of light sources, an optical path correction system is provided on an optical path unique to the light source, and while light emitted from one light source is focused on a specific recording layer by shifting of the objective lens, light irradiated from another light source is focused on another recording layer by the optical path correction system. Thus, information can be reproduced from or recorded in a plurality of recording layers simultaneously and an error in focusing of light onto the plurality of recording layers can be suppressed.

Abstract: In a method of recording or reproducing data out of an optical disk of the present invention, the optical disk is includes a substrate formed with a spiral groove track and a land track formed between nearby portions of the groove track. Header information is periodically recorded in each of the groove track and land track. Beam spots are formed on the land track and groove at the same time. Data are recorded in or reproduced out of the land track and groove track at the same time on the basis of a timing determined by the header information read out of the land track and groove track. When one beam spot formed on either one of the land track and groove track is reading the header information, the other beam spot is inhibited from recording or reproducing data.

Abstract: An optical recording method and apparatus in which a main light spot and a secondary light spot at a predetermined distance ahead of the main light spot in a track direction along which an optical disc rotates are formed on an optical disc. When a mark is recorded by the main light spot in response to a recording signal, an existing mark is partially erased by the secondary light spot during a recording signal period and then completely erased by the main light spot during an erasing signal period. Accordingly, an optimal erasing ratio can be obtained even during fast erasing. Therefore, in the present invention, a mark can be fast recorded on the optical disc, and fast mark recording can be achieved in an optical disc having no special crystallization accelerating layers for accelerating erasing.

Abstract: An optical disc drive with a structure that can reduce the access time to an optical disc required for information recording and reproducing. The optical disc drive includes a turntable on which an optical disc is rotatably loaded, and an optical pickup unit accessing a recording area of the optical disc to record or reproduce information, wherein the optical pickup unit includes at least two optical pickups that independently access different recording areas to simultaneously record information in or reproduce information from the different recording areas.

Abstract: In the case of delaying any one of the detected signals, which are optically obtained from a plurality of trucks, in which the information are respectively recorded under a state that the DC component is removed, a zero cross waveform is extracted from a main detected signal, which is obtained from a main truck. Then, a sub detected signal obtained from a sub truck is held at a timing at which this zero cross waveform is extracted. Further, a sub detected signal, which has been held during a predetermined time frame, is averaged. Moreover, delay amounts with respect to the sub detected signal and the main detected signal are calculated by comparing a waveform of the averaged sub detected signal and the zero cross waveform. Then, the present sub detected signal and the main detected signal are delayed by the calculated delay amounts.

Abstract: An optical pickup apparatus for compensating for the deviation in the thickness of the optical disk and method therefor.

Abstract: When information is reproduced in an optical disk of high recording density or of low recording density, a main beam and sub-beams are emitted onto adjacent tracks. The main beam has a shape longer in a direction perpendicular to the tracks. When the optical disk of high recording density is reproduced, cross talk components from adjacent tracks included in signals reproduced from reflection light of the main beam are canceled by using signals reproduced from reflection lights of the sub-beams. When the optical disk of low recording density is reproduced, information is reproduced with a beam. Thus, two types of optical disks can be reproduced with a simple structure in a compatible way. In the cross talk canceling, discrimination marks formed along the tracks at constant distances are reproduced, and a time difference between the main beam and the sub-beams is corrected precisely by using track jump and detection of discrimination marks.

Abstract: For an overwriting operation, recorded data is read from a disk, and a bit clock is reproduced from the read, recorded data in a clock reproduction circuit (7). Data processing in an encoder (14) is performed in synchronism with the reproduced bit clock. With the above, recording data is output from the encoder (14) in synchronism with the recorded data in the disk whereby recording data to write onto the disk for overwriting is synchronized with the recorded data. A defined recording region is thus precisely overwritten.

Abstract: An optical disc is irradiated with a main beam and a pair of side beams, and respected reflected beams of light are detected by a main detector and a pair of side detectors. A first push-pull signal is generated which includes wobble components obtained by a detection signal from the main detector, and second and third push-pull signals are generated using detection signals from the pair of side detectors. The second and third push-pull signals are added by an adder to generate crosstalk components included in the first push-pull signal, and wobble information of the recording track is generated and output using signals obtained by canceling the crosstalk components in the first push-pull signal including wobble signal components in the recording track.

Abstract: For an overwriting operation, recorded data is read from a disk, and a bit clock is reproduced from the read, recorded data in a clock reproduction circuit (7). Data processing in an encoder (14) is performed in synchronism with the reproduced bit clock. With the above, recording data is output from the encoder (14) in synchronism with the recorded data in the disk whereby recording data to write onto the disk for overwriting is synchronized with the recorded data. A defined recording region is thus precisely overwritten.

Abstract: An optical pickup is described with an electronically adjustable beam spot size for reading optical media. Two proximal light sources are impinged on a selected track of the media and the reflected light is registered by photodetector arrays. The electrical signal generated from the leading detector is delayed, based on a distance between beams and the speed of the media, to achieve a desired amount of temporal coincidence with the electrical signal associated with the lagging beam. The electrical signals are combined, such as in a multiplier circuit, to create a third electrical signal whose response to a data bit can be adjusted to a shorter duration than the responses from either first or second beams. Therefore, the effective spot size may be electronically controlled, wherein light sources of longer wavelengths may be utilized, and optical data storage systems may be configured for reading media having different optical characteristics.

Abstract: An optical disk having a diameter less than 140 mm and, a thickness of 1.2 mm±0.1 mm, with a plurality of record tracks having data recorded thereon as embossed pits representing information and exhibiting a track pitch in the range between 0.646 &mgr;m and 1.05 &mgr;m; with the tracks being divided into a lead-in area, a program area and a lead-out area. The data includes table of contents (TOC) information recorded in a plurality of sectors in at least one TOC track and user information recorded in a plurality of sectors in user tracks; with the TOC information including addresses of start sectors recorded in the user tracks. The data (both user and TOC information) is encoded in a long distance error correction code having at least eight parity symbols, and is run length limited (RLL) modulated.