Abstract: A multimode laser diode stripe is imaged on a light valve, which separates the diode stripe image into a plurality of individually controllable channels. These channels are then imaged onto a recording media where they form a plurality of tracks. Introduction of astigmatism between the multimode laser diode and the light valve causes the laser diode stripe imaged on the light valve to be sharply focussed on its short axis, but less focussed on its elongated axis. This blurring of the stripe's elongated axis at the light valve overcomes near-field non-uniformity in the power distribution of the multimode diode, increasing the reliability and performance of the recording system.

Abstract: Methods and apparatus are provided for detecting and correcting magnification errors while simultaneously reading or writing multiple data tracks with a multi-beam optical disk drive. An optical head for the optical disk drive includes a plurality of laser diodes that generate multiple light beams for reading from or writing to the optical disk, means for detecting a magnification error, and means for compensating for the magnification error to align the multiple light beams with multiple data tracks. A number of opto-mechanical systems are provided for correcting the magnification errors in the beams.

Abstract: A light beam from a light source is introduced to a grating element of a pickup device to create zero order diffracted light, ±first order diffracted light, and ±second order diffracted light. An irradiation system focuses the zero order, ±first order and ±second order diffracted light onto tracks extending on a recording surface of an optical recording medium to form spots. A spot of the zero order diffracted light is formed on a target track, spots of the ±second order diffracted light are formed on tracks adjacent to the target track, and spots of the ±first order diffracted light are formed midway between the spots of the ±zero order and ±second order diffracted light. An optical system guides returning light reflected from the spots to an optical detector. The optical detector has independent light-receiving elements for receiving the returning light.

Abstract: In an optical disc drive, signals from two satellite spots are used to cancel DC offset from a tracking error signal, and for generating a quadrature signal for determining direction of radial movement. The two satellite spots generate signals that are out of phase with the main tracking error signal by about one-fourth period.

Abstract: An optical pickup for simultaneously reading a plurality of data tracks of an optical storage medium is provided. The optical pickup uses a diffractive element to split an illumination beam into a plurality of reading beams which are projected onto a plurality of tracks of the optical storage medium. Apparatus and methods are shown for improving the optical characteristics of the optical pickup by reducing vignetting, optical aberrations, and field curvature. These improvements are achieved by relocating the diffractive element at a greater distance from the laser source, so that a diffractive element having a larger period, and a smaller angle between diffractive orders may be used. The apparatus and methods shown also reduce the number of components and the manufacturing cost of the optical pickup.

Abstract: In an optical head for use in an optical data recording/reproducing apparatus of the present invention, light issuing from a semiconductor layer is split into a main beam that is a zeroth order light and subbeams that are positive and negative first-order diffracted light. A focus error signal is detected from each of the main beam and subbeams. A diffraction optical element causes the main beam and subbeams to differ in light intensity distribution from each other when incident to an object lens. As a result, when a disk or optical recording medium has a thickness error, the focus error signal derived from the main beam and focus error signals derived from the subbeams differ in zero-crossing point from each other. The thickness error is detected on the basis of the difference between the zero-crossing points.

Abstract: An optical pickup device includes an illuminating optical system for focusing light beams, split in a main beam and at least one side beam, onto a track on an information storage surface of an optical storage medium to form optical spots thereon. The device also includes a light detecting optical system for introducing return light reflected back from the information storage surface and a polarizing optical element. The polarizing optical element has regions split at the center of an optical path by a parting line extending at least either in a direction of extension of the track or in a direction perpendicular to the direction of extension. The polarizing optical element also splits the main beam return light at least in two for each of the regions on a plane perpendicular to the optical path of the return light of the reflected main beam in the light detecting optical system. The polarizing optical element is disposed where the return light of the main and side beams is spatially separated.

Abstract: An optical head eliminates an disturbance which occurs in a focus error signal in association with the decentering of an optical disk when an optical spot crosses a track on a storage film surface, and in addition the optical head cancels an off-set which occurs in a tracking error signal in association with the movement of an objective lens. In the constitution of the optical head, phases of wave surfaces of ±1st order diffracted lights are shifted by an amount of &lgr;/2 with a common period by using a phase-inverted diffraction grating the phase of which is inverted with a period of D &lgr;/(2P . NA) in a radial direction of the optical disk, thus causing, on the optical disk, sub-spots to be located on the same track as a main-spot. Taking advantage of this location, focal point shift error signals of the main-spot and the sub-spots are added to each other with an appropriate gain ratio, thereby making it possible to cancel the disturbance which occurs in the focus error signal.

Abstract: The present invention provides an information storage apparatus generating a tracking error signal in which apparatus and method the differential push-pull method is applied to a three spot method using a main beam and two sub-beams, the main beam for writing data on a recording medium and reading data from the recording medium, the information storage apparatus including the following parts. A beam moving part moves the main beam from a blank track to a recorded track. A center value calculating part calculates a center value of the tracking error signal when said main beam is moved from the blank track to the recorded track so that a reference value of the tracking error signal is corrected in accordance with the center value when said main beam writes data on the recording medium.

Abstract: An optical head having a plurality of laser light source and a plurality of photodetectors corresponding to the plurality of laser light sources. The plurality of laser light sources have at least three wavelengths with frequencies which are different from one another, a first laser module includes at least two laser light sources with two frequencies which are in close proximity and two photodetectors corresponding to the at least two laser light sources, and a second laser module includes another laser light source and another photodetector corresponding to the another laser light source.

Abstract: An optical pickup device that is able to record/reproduce information signals for first and second optical discs with different recording capacities. The optical pickup device includes an objective lens for converging first and second light beams of different wavelengths on the signal recording layers of first and second optical discs having different substrate thicknesses, a beam splitter having the same transmittance to the first and second light beams and configured for separating the first and second light beams radiated by first and second light sources to fall on the beam splitter via a first objective lens or a second objective lens, and a hologram element arranged between the objective lens and the beam splitter for limiting the aperture of one of the first light beam and the second light beam and for correcting the spherical aberration caused by difference in the disc substrate thickness of the first and second optical discs.

Abstract: A hologram laser unit to be used for performing recording and reproducing operations of information for an optical disk, includes a light source, a photodetector, and a hologram element which are formed integrally with each other. The hologram element includes: a first hologram for detecting information signals from the optical disk, the first hologram being provided in an area having an effective diameter corresponding to a numerical aperture suitable for the optical disk; and a second hologram for compensating for only a transmitted light amount of light traveling toward the optical disk from the light source, the second hologram being provided contiguously outside the first hologram.

Abstract: A signal generation method capable of generating a cross track signal having a predetermined phase difference from a tracking error signal even in a land and groove recording method in which a land width and a groove width are made equal, wherein a main spot is detected at a split photodetector, a first side spot is detected at a split photodetector, and a second side spot is detected at a split photodetector; a first error is calculated as an error of the optical disk in a radial direction from four detection signals detected at the photodetector, a second error is calculated as the error of two detection signals of the photodetector, a third error is calculated as the error of two detection signals of the third photodetector, and the sum of the second and third errors is subtracted from the first error to calculate a tracking error signal; and a difference between the second error and the third error is found to calculate a cross track signal having a phase shifted by 90° from the tracking error signal

Abstract: An optical pickup apparatus (100) is provided with: a carriage body (80); an optical parts accommodation module (70) mounted on said carriage body and accommodating at least (i) a light beam emitting portion (41, 42, 55) for emitting a light bean, (ii) a light beam receiving portion (57, 65), (iii) a beam splitter (44) and (iv) a grating (43) for generating a sub beam for a tracking adjustment out of the light beam emitted from said light beam emitting portion; and a grating adjustment mechanism (62, 63) for rotating said optical parts accommodation module. The optical parts accommodation module is mounted on said carriage body in such a condition that said optical parts accommodation module is allowed to rotate with an axis line of the light beam, which is irradiated toward a disc, as a rotational center.

Abstract: An optical pickup applies five different light beams at the same time to every second five tracks on a signal plane of a CD-ROM. A record data read system reads record data independently for each light beam system in accordance with outputs of respective light beams reflected from the signal plane, and stores the read record data in the record order. Under the control of a system controller, the optical pickup and record data read system read the record data of the CD-ROM by alternately performing an operation of continuously reading the record data with the five light beam systems during approximately two rotations of the CD-ROM and a track jump operation by seven tracks in a forward direction after the continuous reading operation with a combination of the five light beam systems shows no omission of the record data of the CD-ROM.

Abstract: In a CD-ROM reader system wherein five adjacent tracks of a CD-ROM are separately illuminated by five light beams of an optical pickup, a recorded data readout system simultaneously reads the recorded data of the separate tracks by detecting the received light outputs of the returned beams, and outputs the data in the sequence in which it was recorded. For example, if one light beam becomes unreadable by the recorded data readout system, the system will read the recorded data using the remaining four light beams. This readout is performed in recurring operations in which data is read for approximately one revolution of the CD-ROM; then, after there are no longer any gaps in the combined data, the pickup is track-jumped forward by approximately two tracks. At this point the recorded data is again read for one revolution, and the process repeats.

Abstract: An optical pickup for reading information from a recording medium comprises a light illuminating portion for illuminating a plurality of light beams having different wavefronts onto a recording surface of the recording medium to create a plurality of light spots including a first light spot and a second light spot. The first and second light spots at least partially overlap with each other. A detector receives light beams reflected by the recording medium. The detector has a first light-receiving surface for receiving reflected light of the first light spot and a second light-receiving surface for receiving reflected light of the second light spot.

Abstract: An optical apparatus for reading from and writing to an ultra high density disk and comprising a light source emitting a pencil of light rays to an optical path along an optical axis; two interferometers, a beamsplitter, a quarter-wave plate, and an objective lens. The pencil of light rays is transmitted through the apparatus to become a narrow fringe ring which in turn is used to generate an ultra small spot of light. The resulting ultra small spot of light can address far more storage locations per a same unit area than a conventional much larger spot of light.

Abstract: An optical pickup including a light source for radiating a light beam, a diffraction element for separating a light beam radiated from the light source into at least three beams, namely a main beam and two side beams, an objective lens for converging the light beams separated by the diffraction element on a signal recording surface of the optical recording medium, a light receiving unit having a four-segment first light receiving portion for receiving the main beam reflected by the recording surface of the optical recording medium and second and third light receiving portions arranged on both sides of the first light receiving portion for receiving the side beams reflected by the recording surface of the optical recording medium, and a calculation unit for generating a first tracking signal based on respective outputs of the first light receiving portion and for generating a second tracking signal based on outputs of the second and third light receiving portions.

Abstract: An optical pickup device comprises an objective lens unit having an objective lens, a support member for supporting the objective lens and an objective-lens driving mechanism for driving the objective lens in a radial direction and a focusing direction of an optical disc in such a way that a light beam is focused on an information recording surface of the optical disc; and a main unit having an optical irradiation system which includes a light source for emitting a light beam and guides the light beam to the objective lens, and an optical detection system which includes a photo-sensor and guides reflected light from the information recording surface to the photo-sensor via the objective lens.

Abstract: A device for recording and/or reproducing an optical record carrier (1), comprises an optical system for projecting a first, a second and a third optical beam at a first (11), a second (12) and a third spot (13) at the record carrier (1). The device further comprises detection elements primary position signals (D5, C, D1) which is indicative for an amount of radiation reflected by the record carrier at said thoses spots (11). The device further comprises signal processing means (34.1, . . . 34.4; 35.1, . . . 35.4) for generating a plurality of secondary position signals (S1, S2, S3, S4) in response to the primary position signals (D5, C, D1). A selection element (36) selects one of the position signals (S1, S2, D1, S3, S4) as an output signal (WRE) in response to a selection signal (SEL). The selection signal (SEL) is derived from the output signal (WRE) of the selection element (36).

Abstract: An optical pickup apparatus that is capable of recording and reproducing various types of optical discs having a recording format, such as a different substrate thickness, etc., without an additional aperture number control device. In the apparatus, at least two light sources generate a different wavelength of lights. A focusing optical system focuses a light from the light source onto the optical recording medium. A receiving optical system receives a light reflected from the recording medium. The focusing optical system is configured in such a manner to generate a predetermined range of aberration in a light spot formed on the optical medium by the lights from any one of the light sources. Since the apparatus can access recording media having a different recording format by using an optical system and an aberration optimized for a single optical recording medium without an additional aperture number control device, so that its configuration is simplified.

Abstract: An optical pickup apparatus has a first light source for emitting a first laser beam, a second light source for emitting a second laser beam whose wavelength is different from that of the first laser beam, a first grating for allowing the first laser beam to pass as a 0th order light, diffracting the second laser beam, and generating a primary diffracted light having an optical axis which closely coincides with that of the first laser beam, and a second grating for using the laser beam supplied from the first grating as a main beam and generating sub-beams for generating a tracking error signal of a three-beam method with respect to the main beam, wherein the first and second light sources and the first and second gratings are constructed as an integrated unit, and the unit is held in a holding member for holding the optical parts of the optical system.

Abstract: An optical pick-up generates a 0-th order diffraction light and ±1st order diffraction lights by a diffraction grating and irradiates the same to an optical disc. The ±1st order diffraction lights have phase distributions equivalent to a wavefront aberration of the optical disc when there is a tilt in the optical disc. Distances between the center of the main optical spot and centers of sub optical spots in a disc radial direction on a recording surface are whole multiples of a track pitch. The generation circuit generates a main push-pull signal corresponding to the 0-th order diffraction light and first and second sub push-pull signals corresponding to the ±1st order diffraction lights and generates tracking error signals TE as differential push-pull signals obtained by subtracting a sum signal of the first and second sub push-pull signals from the main push-pull signal.

Abstract: An optical recording/reproducing apparatus having drive means for rotating a recording medium, an optical head for applying light to the recording medium being rotated by the drive means, thereby to record data signals on the recording medium or reproducing data from the recording medium, and a signal-processing circuit for processing a signal detected by the optical head. The optical head comprises a light source for emitting light, an objective lens, and signal detecting means. The objective lens has a numerical aperture NA, where 0.5<NA≦0.6. The apparatus can reliably record data on and reproduce data from high-density optical recording media that have different track pitches.

Abstract: A multiple channel scanning device has a scanning head with multiple columns of apertures that emit light which is projected to a small spot on the surface of a recorded medium. Light returned from the medium reenters the apertures and is conducted to detectors. In a preferred embodiment, the scanning head is rapidly oscillated (may be on the order of 100 kHz rate), in a direction parallel to the columns. The medium is moved in a direction perpendicular to the columns so that the same recorded regions pass beneath successive columns of apertures. The data from the detectors is image-processed to improve the quality of data reading using the successive readings of the same data regions. This allows errors to be corrected and throughput to be improved.

Abstract: A method of tracking servo for an optical pickup device comprises the steps of generating each individual push pull signal (an SPP1 signal, an SPP2 signal and an MPP signal) with a photo detector composed of a main photo detector having four photo-detecting sections crosswise and two side photo detectors having respectively two photo-detecting sections left and right, and generating a tracking error signal (a DPP signal) on the basis of operational output from the push pull signals resulting from respectively canceling the amounts of DC offset produced in each of the push pull.

Abstract: A grating surface of a diffraction grating diffracts a laser beam emitted from a semiconductor laser device in ±1st order directions. The grating surface is formed in a rectangular or elliptic shape in such dimensions that a light spot formed on an objective lens by ±1st order diffracted beams is located in an aperture of the objective lens and not displaced from the aperture even if the objective lens is horizontally moved in a tracking operation. A grating surface of another diffraction grating has a width smaller than the width of an overlap region of a light spot on the diffraction grating corresponding to a part of a beam, diffracted in the +1st direction, entering an objective lens and a light spot on the diffraction grating corresponding to a part of a beam, diffracted in the −1st direction, entering the objective lens.

Abstract: An optical disk unit for recording information on and reproducing information from a disk recording medium by projecting a light beam thereonto includes a signal level detection part detecting a level of a track error signal generated based on reflected light of the light beam from the disk recording medium, a scattered light detection part detecting scattering of the reflected light, and an off-track detection part which detects an off-track of the light beam using detection signals supplied from the signal level detection part and scattered light detection part.

Abstract: In an optical pickup method and device of the present invention, a grating unit separates a light beam, emitted by a light source, into a 0th order diffracted beam and 1st order diffracted beams. An objective lens focuses the diffracted beams, sent from the grating unit, onto a recording surface of an optical recording medium through a transparent substrate of the medium, so that a main spot is formed on the recording surface by the 0th order diffracted beam and sub-spots, interposing the main spot therebetween, are formed on the recording surface by the 1st order diffracted beams. A reflection beam detector receives reflection beams from the main spot and the sub-spots of the medium to generate detection signals from the received reflection beams.

Abstract: An objective lens and an optical head including the objective lens for reading information contained on substrates having different thicknesses using laser beams having different wavelengths. The objective lens includes an annular phase shifter for decreasing an aberration of a focused spot of each of the laser beams. The annular phase shifter can be optimally combined with the objective lens having inner and outer regions each having a different substrate thicknesses.

Abstract: A compatible optical disk player and data recording and/or reproducing method includes a laser beam source including a first laser diode and a second laser diode, where the first laser diode emits a first laser beam of a first wavelength for recording and/or reproducing the data on/from a first optical disk including a first recording density, and the second laser diode emits a second laser beam of a second wavelength for recording and/or reproducing the data on/from a second optical disk including a second recording density. A diffraction grating selectively splits the first and the second laser beams into a main ray and two sub-rays depending on which optical disk is to be accessed. A photo-detector selectively receives the three rays of the first laser beam and the three rays of the second laser beam at different detecting portions for the data recording and/or reproducing and error detection and compensation.

Abstract: The present invention provides an optical system having a read mode, during which multiple tracks of an optical disk are simultaneously read, and a write mode, during which data is written to at least one track of the optical disk. The multiple light beams employed during read mode may be generated by a single laser diode operated at low power used in combination with a diffractive element, multiple laser diodes, or combinations thereof.

Abstract: A track discrimination signal can be generated without requiring the use of a large number of parts or a complex device configuration even when an optical recording medium adapted to the “land/groove recording system” such as a “DVD-RAM” is used. A main light spot is and auxiliary light spots are formed on an optical disc for signal recording and signal reproduction.

Abstract: The spot diameter D3 of a side beam 21 imaged on a disc 5 is set to at least 2.5 times as large as that of a main beam. Via this configuration, an output signal from a detector detecting a reflected light via a side beam, that is, a signal representing a different in the output from photo-detection devices split by split lines in the radial contains a negligible track cross component caused by a beam spot crossing a track. The signal substantially contains a DC offset component alone caused by the shift of an objective lens in the radial direction under tracking control. Thus, by subtracting the output signal of the detector from the push-pull signal of the main beam, a tracking signal substantially containing no DC offset.

Abstract: An optical pickup apparatus compatible with at least two types of optical recording media, using light beams having respective different wavelengths for recording and reading information, the optical pickup apparatus including two laser light sources to emit light beams having the different wavelengths, respectively, a holographic lens, including a holographic ring, to transmittal of the light beams emitted from the laser light sources in an inner region of the holographic ring, and diffracting a specific light beam among the light beams emitted from the laser light sources in an outer region relative to the inner region, an objective lens to focus the light beams passed through the holographic ring lens on the respective information recording surfaces of the two types of the optical recording media, optical elements to alter optical paths of the light beams reflected from the information recording surfaces of the optical recording media; and two photodetectors to individually detect optical information from

Abstract: In an optical head for recording on or reproducing from a plurality of kinds of optical information recording media corresponding to a plurality of kinds of different wavelengths, coma aberration is prevented, and low price and high reliability are realized. To that end, in an optical head constituted by laser light sources of three wavelengths and photodetectors corresponding to the laser light sources of the three wavelengths, a two-laser module including laser light sources of two adjacent wavelengths and photodetectors corresponding to the laser light sources, a laser module including a laser light source of the rest one wavelength and a photodetector corresponding to the laser light source, and a dichroic mirror bonded with a rising mirror are combined.

Abstract: An optical pickup including a light source for radiating a light beam, a diffraction element for separating a light beam radiated from the light source into at least three beams, namely a main beam and two side beams, an objective lens for converging the light beams separated by the diffraction element on a signal recording surface of the optical recording medium, a light receiving unit having a four-segment first light receiving portion for receiving the main beam reflected by the recording surface of the optical recording medium and second and third light receiving portions arranged on both sides of the first light receiving portion for receiving the side beams reflected by the recording surface of the optical recording medium, and a calculation unit for generating a first tracking signal based on respective outputs of the first light receiving portion and for generating a second tracking signal based on outputs of the second and third light receiving portions.

Abstract: An optical disk apparatus for reproducing information from plural types of information carriers or for recording information to plural types of information carriers, has two or more light sources with different wavelengths, a converging part for converging a light beam emitted from each of the light sources on said information carrier, a movement part for moving the converged spot of the light beam converged by the converging part in a direction substantially perpendicular to the surface of the information carrier, a convergence condition detection part for outputting a signal corresponding to the convergence condition of the light beam on the information carrier, an amplitude detection part for measuring the amplitude of the signal of the convergence condition detection part, and a focus control part for driving the movement part in accordance with the output signal of the convergence condition detection part and for performing control so that the convergence condition of the light beam on the information ca

Abstract: An optical head having a phase-shifting diffraction grating includes a diffraction grating for dividing the light from a light source into a plus first order diffracted light, a zero order light, and a minus first order diffracted light. An objective lens focuses light from the light source passing through the diffraction grating onto an optical recording medium, and a photodetector receives a reflected light from the optical recording medium. A signal processing circuit generates a track error signal according to an output of the photodetector. The phase difference between lights on different regions of the diffraction grating is &pgr;/2 radians allowing the optical head to detect a land/groove position on an optical recording medium even if the land and groove have identical widths.

Abstract: An initial crystallization method of a recording medium such as a phase-change optical disk, which comprises forming a light spot composed of at least two flat elliptical beam spots each having a long axis direction and a short axis direction and irradiating a rotating recording medium with the light spot such that the long axis direction of the beam spots becomes other direction than the parallel direction to the track direction of the recording medium, wherein the above-described light spot has at least two peaks of light intensity in the short axis direction and the interval of said two peaks of light intensity is 10 &mgr;m or smaller but not smaller than 2 &mgr;m, and a device for carrying out the initial crystallization method. By the initial crystallization method and the device thereof, the initial crystallization of the recording film of the recording medium can be surely carried out at a high speed without causing non-uniformity.

Abstract: The invention provides a near-field photochromic device for a supra-density optical memory, comprising a scanner carrying a data storage medium, an optical head having a tip, to be used for recording, readout and erasing, and located in close proximity to the data storage medium, and at least two lasers, alternatingly optically alignable with the optical head, wherein the data storage medium is a film consisting of a photochromic compound and wherein the distance between the tip and the data storage medium is within the limits of the near field of the optical head.

Abstract: A composite interferometer and electro-optical prism provide a means to control the position of a spot of light to read and write data on an optical disc. In this invention each light ray from a spectral source of a cone of light rays is regenerated into a plurality of light rays by an interferometer. These rays are transmitted through an electro-optic crystal and focused by a lens into a constructive interference fringe on an optical disc. A voltage across the electro-optical crystal and magnetic field inside the spectral source define the position of the constructive interference fringe on the disc.

Abstract: An optical pickup device has a single light beam path in which at least one or either of a plurality of kinds of light beams (different from each other in, for example, wavelength) for respective recording densities and/or recording-medium-thicknesses proceeds toward a surface of an optical recording medium and proceeds to a light beam detector after being reflected by the surface.

Abstract: An optical pickup device has a single light beam path for common use in treating or passing either of a plurality of kinds of light beams for respective recording densities and/or recording-medium-thicknesses different from each other, in other words, at least one or either of the plurality of kinds of light beams is introduced into the common single light beam path which may includes a single quarter-wave plate and/or single collimator and/or single objective.

Abstract: Disclosed is an optical pickup.

Abstract: A focus detection system for use in a multi-beam optical pickup assembly is provided that uses an optical element, either a holographic element or diffractive element, to split beams reflected off of a data-bearing surface of an optical disk into a plurality of data beams and a plurality of focus beams. The optical element also introduces astigmatism into the focus beams. The focus beams are projected onto focus detectors configured to account for overlap between adjacent focus beams to produce an accurate focus error signal.

Abstract: An optical pickup apparatus having compatibility with a recodable compact disk (CD-R) and a digital video disk (DVD), which uses a wavelength of one of a first light beam and a second light beam according to the recording medium to be used. In the optical pickup apparatus, laser light sources emit a first light beam having a relatively shorter wavelength for the DVD and a second light beam having a longer wavelength for the CD-R, respectively. An objective lens has a predetermined focal length in accordance with the position of an information recording surface in the DVD. An optical path control unit controls the path of light beams so that the light beam emitted from one of the laser light sources is directed to the objective lens and the light output from the objective lens is directed to the optical detection unit.

Abstract: An optical pickup including a light source for radiating a light beam, a diffraction element for separating a light beam radiated from the light source into at least three beams, namely a main beam and two side beams, an objective lens for converging the light beams separated by the diffraction element on a signal recording surface of the optical recording medium, a light receiving unit having a four-segment first light receiving portion for receiving the main beam reflected by the recording surface of the optical recording medium and second and third light receiving portions arranged on both sides of the first light receiving portion for receiving the side beams reflected by the recording surface of the optical recording medium, and a calculation unit for generating a first tracking signal based on respective outputs of the first light receiving portion and for generating a second tracking signal based on outputs of the second and third light receiving portions.

Abstract: A recording or reproduction device with a three-point scanning arrangement compatible for use with recording media having different track spacings. The invention makes it possible, without changing the setting of the three-point scanning system, to use recording media having different track spacings. According to the invention, the three-point scanning system is set in such a way that the scanning center points have a lateral spacing from one another which is within a range of a first product, formed by a first predetermined value and the first track spacing, and a second product, formed by a second predetermined value and the second track spacing, the range being less than 8 percent of the value of the first product.