Abstract: An optical pickup device, comprises light sources to emit a first light flux having a wavelength ?1 (380 nm<?1<450 nm); a second light flux having a wavelength ?2 (600 nm<?2<700 nm); and a light-converging optical system. The light-converging optical system converges the first light flux on a first optical information recording medium through a protective layer having a thickness t1 and the light-converging optical system converges the second light flux on a second optical information recording medium through a protective layer having a thickness t2. The light-converging optical system forms a first spot on the information recording surface of the first optical information recording medium by using N-th order diffracted light ray generated, and the light-converging optical system forms a second spot on the information recording surface of the second optical information recording medium by using M-th order (M?N) diffracted light ray generated.

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: An information recording and/or reproducing apparatus includes a laser light source from which a laser beam having a wavelength of from 220 nm to 280 nm exits; and a converging lens unit disposed at a nearfield area of a recording medium and upon which the laser beam from the laser light source is incident. The converging lens unit includes an objective lens and a solid immersion lens. The solid immersion lens is disposed between the objective lens and the recording medium, and is formed of a highly refractive material having a high transmittance. The information recording and/or reproducing apparatus records an information signal onto or reproduces an information signal from the recording medium by irradiating the recording medium with the laser beam from the laser light source.

Abstract: An optical pickup comprises: first and second semiconductor lasers (11, 14); a hologram element (17) for diffracting light reflected by an optical information recording medium (9 or 12); and a plurality of photodetectors (18-23). The hologram element (17) has two or more different diffraction regions. The plurality of photodetectors (18-23) are provided away from the first and second semiconductor lasers (11, 14) at both sides thereof along an extended line of a line between light emission positions of the first and second semiconductor lasers (11, 14). The diffracted light generated from the light beam of the first wavelength (10) by the hologram element (17) and the diffracted light generated from the light beam of the second wavelength (13) by the hologram element (17) are collected at substantially the same position at one side, and part (18, 19) of the plurality of photodetectors (18-23) are provided at the position.

Abstract: A tracking offset is reduced. The effect of an SPP signal fluctuation is reduced by using a variable mixing ratio DPP method, and a residual tracking offset is minimized.

Abstract: An optical disk apparatus includes a digital signal processor, a photo-detector circuit, and a sample-and-hold circuit. By using a sampling-timing signal generated by the sampling-timing signal based on a sampling-timing signal transmitted from the digital signal processor to the photo-detector circuit through a flexible cable, the sample-and-hold circuit can be operated. Based on a sampling-timing signal dedicated for a side spot, the sample-and-hold circuit can be operated.

Abstract: To provide an optical pickup device and optical disk device capable of realizing at least one of thickness reduction, size reduction and suppression against characteristic deterioration even where coping with various wavelengths of laser including a blue laser. An optical pickup device comprising light sources for respectively emitting a plurality of different wavelengths of light, unit structured for causing at least a part of the light emitted from the light sources to pass a same optical path; and focusing unit for focusing the light. The focusing unit includes at least first and second focusing parts, the first focusing part being to focus mainly a wavelength of light different from a wavelength of light to be mainly focused by the second focusing part.

Abstract: An optical pickup for recording and/or reproducing data with respect to a multilayer recording medium having a plurality of recording layers, where the optical pickup includes a light source emitting a beam having a predetermined wavelength, a diffraction unit separating the beam emitted from the light source into a main beam and a sub-beam, and a photodetector having a main photodetector detecting a main beam reflected from the multilayer recording medium and a sub-photodetector detecting the sub-beam. In the optical pickup, the main photodetector and sub-photodetector are separated a predetermined distance from each other so that a beam spot formed by the beam reflected from a defocus recording layer is not detected by the sub-photodetector.

Abstract: The optical pickup apparatus includes a light emitting means, an optical means, and an optical detection means. The light emitting means emits a single beam. The optical means diffracts the single beam, focuses the optical spot of the diffracted beam on a track, and transmits the diffracted beam to an outside. The optical detection means includes a first optical detection unit on which a central beam having a 0-order diffraction coefficient is focused, and second and third optical detection units on which side beams having ±1 diffraction coefficients are focused, respectively. Each optical detection unit is segmented into a specific number of optical detection areas, and at least one of the optical detection units is provided with an optical detection area on which a tracking error signal used to compensate for tracking offset attributable to optical axis offset of an objective lens is not formed.

Abstract: When recording/reproducing an optical disc having a recording layer of multi-layer structure, an unwanted optical beam reflected from a recording layer other than a target layer for recording/reproduction is incident on a photodetector to cause an unwanted disturbance component to leak to a detection signal, giving rise to a degradation in the quality of a tracking control signal. In an optical pickup apparatus, for suppression of the degradation, an optical element is mounted having a diffraction area for diffracting part of the optical beam and light receiving planes for sub-optical beams are provided each of which has a light shielding zone or dead zone of a predetermined width on its central sectioning line.

Abstract: An apparatus for optical pickup is disclosed which minimizes offset element occurring between the recorded and non-recorded pattern when object lenses are configured off-axis along the tracks on the optical storage medium. The optical pickup of the present invention minimizes the offset voltage level change by passing the incident beam into the optical storage as one beam and then dividing the beam into three beams and by preventing the AC signal of sub beam from reaching the light detecting means.

Abstract: In the past there has been a problem that on a detection surface the influence of interference causes a defocusing signal to degrade, narrowing the range in which spherical aberration can be stably detected. Accordingly, a diffraction grating is used to focus the inner and outer sides of luminous flux on separate optical detectors before the optical flux is focused on an optical detector and defocusing signals are independently calculated to find the difference therebetween, thereby providing a spherical aberration signal. This makes it possible to detect spherical aberration signals more stably.

Abstract: An optical information reproducing apparatus and an optical information reproducing method using the same are provided. The optical information reproducing apparatus includes: a reference beam providing unit which inputs a reference beam to a reproduction recording area to be reproduced and a peripheral recording area around the reproduction recording area on an optical information recording medium, a peripheral beam detecting unit which transmits a reproduction beam reproduced from the reproduction recording area in response to the reference beam and detects a peripheral beam reproduced from the peripheral recording area, a tracking servo unit which analyzes optical information of the detected peripheral beam and controls a tracking position, and a reproduction beam detecting unit which detects the reproduction beam having pass through the peripheral beam detecting unit.

Abstract: An optical pickup apparatus includes a first light source to emit a first light beam having a predetermined wavelength, a first optical path changer to change a proceeding path of the first light beam, an objective lens to focus the first light beam on a recording medium, a diffraction member to divide the first light beam reflected by the recording medium into five light regions, the diffraction member having a first diffraction region having a wide width in a direction corresponding to a tangential direction of the recording medium and second through fifth diffraction regions sequentially arranged around the outside of the first diffraction region in a direction corresponding to a radial direction of the recording medium, and a first photodetector having first through fifth light receiving portions to receive the first light beam reflected by the recording medium.

Abstract: An optical-information recording medium includes a substrate that includes a servo surface having a servo pattern thereon; an information recording layer laminated on the servo surface of the substrate capable of recording information as a hologram produced by interference between an information beam containing the information and a reference beam; an address servo area that is formed as a part of the servo pattern, and that records therein address information and clock information for aligning a beam, emitted from an optical-information recording apparatus for recording information in the information recording layer, to a target position in the information recording layer; and a following up servo area that is formed as a part of the servo pattern, and that is to be irradiated by the beam to make the beam follow a rotation of the optical-information recording medium.

Abstract: On an optical disk in a recording and/or playback apparatus, the position at which the thickness error of a light transmission layer is in the optical axis of an objective lens 11, and the position at which the recording/playback of information is performed is in the optical axis of a two-group objective lens 20, so that they are spaced apart from each other, making it impossible to accurately detect the thickness error at the position where the recording/playback of information is performed. Further, to chronologically compensate for the space between them, an excess circuit is required. In view of this, a first reflection light 107a reflected by a medium surface 106a of the optical disk is received to detect the focal error with respect to the medium surface, and a second reflection light 107b reflected by the surface of a light transmission layer 106b formed on the medium surface 106a to detect the focal error with respect to the surface of the light transmission layer 106b.

Abstract: In a configuration in which side beams scan in positions that are offset with respect to a main beam by approximately (¼+n)P or (¾+n)P in the radial direction of an optical disk, a differential signal is generated from push-pull signals of the return lights of the side beams to generate a track-cross signal. In a configuration in which side beams scan in positions that are offset with respect to a main beam by approximately (¼+n)P or (¾+n)P in the radial direction of an optical disk, far-side or near-side light detection results of the return lights of the side beams are processed and computed with respect to a push-pull signal of the return light of the main beam.

Abstract: Disclosed are a module to detect a tracking error signal that is easy to be assembled and robust against variation in a track angle, a diffraction grating, an optical pickup, and an optical disc apparatus that enable the module to be realized, wherein a diffraction grating divided into at least three areas, first, second, and third areas, is used; the second area is an area that do not diffract light; and focusing positions of light diffracted by the first and third areas sandwiching the second area therebetween on an optical disc are arranged with a spacing of (2n?1)×t/2 in an optical disc radial direction, respectively, where n is a nonnegative integer and t is a spacing of guide grooves of the optical disc.

Abstract: In order to generate a lens position signal, which describes the position of the optical axis of an objective lens of an apparatus for reading from and/or writing to an optical recording medium with regard to the optical axis of the remaining components contained in an optical scanner, the application of the DPP method is proposed in accordance with a first exemplary embodiment, wherein a primary-beam error signal and a secondary-beam error signal are obtained with the aid of the DPP method, wherein the desired lens position signal is generated by addition of the primary-beam error signal and the secondary-beam error signal. In accordance with a second exemplary embodiment, it is not necessary to generate a primary beam, rather it suffices to detect the secondary beams reflected from the optical recording medium in order to obtain the lens position signal by addition of the secondary-beam error signals generated in a manner dependent thereon.

Abstract: An optical reproducing apparatus that uses a hologram laser module and is applicable to a DVD Multi drive, wherein five sub spots of light in total that are most suitable to perform the differential push-pull tracking both for DVD-RAM and for DVD-R/RW are irradiated on the disk, respectively, and influence of several sub spots that are unnecessary in recording and reproducing a disk is canceled out by calculation, to realize an optical head that is compatible with the DVD Multi drive using a hologram laser module, and thereby providing a small-size, high-performance optical reproducing apparatus.

Abstract: An optical pickup device is equipped with a diffraction element (8) that includes liquid crystal, two transparent electrodes sandwiching the liquid crystal, and a liquid crystal control portion (21) with electrodes connected electrically to the transparent electrode for controlling a voltage to be applied between the two transparent electrodes. The diffraction element (8) is provided with two types of diffraction areas (19) and (20). Each of the diffraction areas (19) and (20) generate predetermined diffracted light only from one of different wavelengths of light beams. The transparent electrodes of the diffraction areas (19) and (20) that are patterned are connected electrically to different electrodes (22c) and (22a), respectively.

Abstract: An apparatus for optically reproducing and recording information includes a light source, an objective lens, a light detecting element, and a processor. The objective lens focuses light beams emitted from the light source on an optical recording medium having tracks disposed at a track pitch. The wavelength of the light beams is greater than the track pitch of the medium. The light detecting element receives light beams reflected from the medium. The light detecting element includes a first region that receives substantially only light beams generated by interference between zeroth-order diffracted beams and first-order diffracted beams among the light beams reflected from the tracks of the medium and a second region that receives substantially only the zeroth-order diffracted beams. The processor generates focusing error signals using astigmatic focusing error detection on the basis of an output from the second region of the light detecting element.

Abstract: An optical head includes a blue color laser beam sources, a red color laser beam sources, a dichroic prism, a collimator lens, a beam splitter, an objective lens, a photo detector element, a detection lens, and a hologram element having a first hologram and a second hologram and the first hologram changes a phase of a +1st order diffraction light of a blue color laser beam so that its condensing point falls on a second photo detecting portion and the second hologram changes a phase of a ?1st order diffraction light of a red color laser beam so that its condensing point falls on a third photo detecting portion.

Abstract: In a photo pickup device, a hologram element 13 is divided into eight areas. In operation, the hologram elements adds different lens powers to four diffraction lights forming two pairs of diffraction-light groups. In the photo pickup device, a light receiving element 19 is divided into four areas to receive these diffraction lights. The photo pickup device outputs signals corresponding to four quadrants A, B, C and D forming a reflection light from an optical disc 5, allowing a focus-error signal to be calculated in the same logic as an “astigmatism method”.

Abstract: An optical pickup apparatus, comprising: a light source to emit a light flux; a light converging system including an objective lens to converge the light flux emitted from said light source onto an optical information recording medium; a first diffraction element placed within an optical path up to the optical information recording medium; a light flux splitting element that is placed within the optical path from said light source up to the optical information recording medium and that splits an incident light flux emitted by the light source; a monitor element that receives a light flux split by said light flux splitting element and outputs a signal according to a received light amount; a second diffraction element placed between said light flux splitting element and said monitor element; and a control section that controls the drive of said light source according to the signal from said monitor element.

Abstract: According to the present invention, an optical pickup device forms one main spot, a first subspot, and a second subspot by irradiation of light on an optical disk having a groove part and a land part. The optical pickup device includes operation circuits which indicate a deviation between each of the optical spots and a track, and ? detecting means for detecting such an ? value that a difference in absolute value between SPP1 and ?SPP2 falls in a preset range, where an AC amplitude of a push-pull signal of the first subspot is SPP1, and an AC amplitude of a push-pull signal of the second subspot is SPP2, wherein SPP1??SPP2 (? is a constant) is a land/groove discriminating signal. With this, in the optical pickup device for recording and reproducing information on/from the optical disk having a land/groove part, it is possible to generate a land/groove discriminating signal and a tracking error signal without an offset, thereby performing excellent tracking control.

Abstract: Disclosed is an optical head in which position adjustment of a photodetector light receiving surface or component parts may be simplified, production costs may be reduced and operational reliability may be improved. The optical head includes a light source 22, radiating light of a preset wavelength, an objective lens 27 for condensing the outgoing light from the light source 22 on an optical disc 2 and for condensing the return light from the optical disc 2, a beam splitter 25 for branching the optical path of the return light reflected by the optical disc 2, and for collimating the branched return light so as to be parallel to the outgoing light from the light source 22, a composite optical component including a splitting prism 30 arranged on a site of incidence of the branched return light for spatially splitting the return light, and a light receiving unit for receiving plural return light beams spatially split by the splitting prism 30 for producing focusing error signals.

Abstract: A tracking error signal generation device includes a splitting and convergence section for splitting an optical beam into a main beam and a sub beam; a two-portion main beam detection section for detecting the main beam; a main beam push-pull signal generation section for generating a main beam push-pull signal; a two-portion sub beam detection section for detecting the sub beam; a sub beam push-pull signal generation section for generating a sub beam push-pull signal; a displacement amount detection section for detecting a displacement amount of the main beam push-pull signal from a reference value based on the main beam push-pull signal and the sub beam push-pull signal; and a tracking error signal generation section for generating a tracking error signal by correcting either the main beam push-pull signal or the sub beam push-pull signal based on the displacement amount.

Abstract: An optical head unit is provided including a first light source emitting a light with a first wavelength, a second light source emitting a light with a second wavelength, and a third light source emitting a light with a third wavelength. The optical head unit also includes a first objective lens irradiating the light emitted from the first light source onto an optical recording medium, a second objective lens irradiating the light emitted from the second light source or the light emitted from the third light source onto an optical recording medium, and a photodetector receiving a reflected light from the optical recording medium.

Abstract: A simulation device for simulating an operation of a system constituted by a plurality of machines. An operation program is executed by an arithmetic processing unit in a controller of a machine or by an information processing device having a function of analyzing the operation program equivalent to the controller of the machine, to obtain operation command data for the machine. The obtained operation command data of the machine with lapsing time information are received by the simulation device and stored as historical data. Operation programs of all of the machines constituting the system are executed to obtain historical data of operations of the machines, which are united by arranging the data in time series from a start of simultaneous operations of the machines based on the lapsing time information. Images of three-dimensional models of the machines are displayed by animation based on the united historical data.

Abstract: A light emitting device according to the present invention includes: a first light source for emitting light having a first wavelength; and a second light source for emitting light having a second wavelength which is different from the first wavelength, wherein the first light source and the second light source are arranged in the same housing, and a relationship of ?h1>?h2 is satisfied, where ?h1 denotes an angle (full-width-half-maximum) of radiation of the light emitted from the first light source in the horizontal direction, and ?h2 denotes an angle (full-width-half-maximum) of radiation of the light emitted from the second light source in the horizontal direction.

Abstract: A scanning module for scanning a document is provided. The scanning module comprises: a chassis; a light source on the chassis for emitting a light ray onto the document; a plurality of reflectors inside the chassis; a lens inside the chassis; an image sensing device inside the chassis, an image of the document being reflected by the plurality of reflectors and formed on the image sensing device, the image sensing device including a plurality of sensing cells; and a plurality of microlenses on the plurality of sensing cells, each of the plurality of microlenses having a top surface and a bottom surface, the top surface having a plurality of notches as an input window for changing an incident angle of the light ray, the bottom surface having a plurality of round curves as an output window for further focusing the light ray.

Abstract: An optical reproducing apparatus that uses a hologram laser module and is applicable to a DVD Multi drive, wherein five sub spots of light in total that are most suitable to perform the differential push-pull tracking both for DVD-RAM and for DVD-R/RW are irradiated on the disk, respectively, and influence of several sub spots that are unnecessary in recording and reproducing a disk is canceled out by calculation, to realize an optical head that is compatible with the DVD Multi drive using a hologram laser module, and thereby providing a small-size, high-performance optical reproducing apparatus.

Abstract: Laser beams respectively emitted from a SHG blue laser unit and a red semiconductor laser unit that have photo detectors respectively are turned into parallel lights by a collimator lens and then coupled by a dielectric multi-layer film mirror so as to be propagated on the same optical axis. The dielectric multi-layer film mirror is configured so as to transmit light with a wavelength of 500 nm or shorter and reflect light with a wavelength of 500 nm or longer for both P wave and S wave. The lights that are transmitted and reflected by the dielectric multi-layer film mirror pass through a polarizing hologram and a phase variable wave plate and are focused on an optical disk by an objective lens. In this manner, a simple configuration can realize a compatibility with many types of optical disks and a stable signal detection even when using a polarizing optical detection system.

Abstract: An optical head for reproducing information contained on an optical information disk includes a plurality of light sources and a plurality of light receiving elements in correspondence with the plurality of laser light sources. There is constructed a constitution in which one laser light source in the plurality of laser light sources is constituted by an individual laser diode and which includes a laser module constituted by other laser light sources and the plurality of light receiving elements to thereby enable to realize the small size of the optical head.

Abstract: A holographic ROM reader having a servo control is disclosed. The holographic ROM reader includes an objective lens for focusing light reflected from a storage medium, a pinhole plate provided with a pinhole, a diffraction grating, embedded into the pinhole of the pinhole plate, for diffracting the light focused by the objective lens to produce 0th order diffracted light, +1st order diffracted light and ?1st order diffracted light therethrough, a photo detector for detecting the amounts of the 0th order, the +1st order and the ?1st order diffracted light, and a servo controller for comparing an amount of light of an overlapped area of the 0th order diffracted light and the +1st order diffracted light with an amount of light of an overlapped area of the 0th order diffracted light and the ?1st order diffracted light to control the position of the objective lens to pass the light through a center of the diffraction grating if the amounts of light are not identical to each other.

Abstract: An optical pickup device, comprises light sources to emit a first light flux having a wavelength ?1 (380 nm<?1<450 nm); a second light flux having a wavelength ?2 (600 nm<?2<700 nm); and a light-converging optical system. The light-converging optical system converges the first light flux on a first optical information recording medium through a protective layer having a thickness t1 and the light-converging optical system converges the second light flux on a second optical information recording medium through a protective layer having a thickness t2. The light-converging optical system forms a first spot on the information recording surface of the first optical information recording medium by using N-th order diffracted light ray generated, and the light-converging optical system forms a second spot on the information recording surface of the second optical information recording medium by using M-th order (M?N) diffracted light ray generated.

Abstract: An object of the invention is to provide a structure for suppressing occurrence of a track offset in a tracking control using DPP method, and simplified apparatus assembly adjustment. When a diffraction grating provided in an optical pick-up apparatus, diffracts light irradiated from a semiconductor laser at least into zero-order diffraction light and ± first-order diffraction light, disposed adjacent to diffraction area alternately in an extension direction of a grating groove, and an effective diameter of light beam with which the diffraction grating is irradiated is D, and a number of divisions into which the effective diameter D is divided is m (m is an integer of 3 or more), a width W1 and a width W2 are formed to meet W1=W2=D/m.

Abstract: An optical pickup apparatus includes first, second and third light sources; a light converging optical system including a first objective optical element and a second objective optical element, wherein the first objective optical element converges the light flux emitted from the first light source on a first information recording surface, the second objective optical element converges the light flux emitted from the third light source on a third information recording surface, and the first objective optical element or the second objective optical element converges the light flux emitted from the second light source on a second information recording surface; a lens holder holding the first objective optical element and the second objective element therein; and a chromatic aberration correcting element which corrects a chromatic aberration caused by a wavelength variation in a light flux emitted by the first light source.

Abstract: At the initialization, a tilt mechanism 9 is activated in a state where an optical pick-up 3 is fixed, and set up at a position where an E-F phase difference obtained in a signal processing portion 4 is 180°. Thereafter, a reproducing operation is started. During the reproducing operation, the tilt mechanism 9 is not activated and the focus control is made with the focus servo by moving the optical pick-up 3 up or down, while the level of a focus error signal is within a certain range. Further, if the level of focus error signal is beyond the certain range because the optical disk 1 is greatly inclined, the tilt mechanism 9 is activated to cause the optical disk 1 to come closer to the optical pick-up 3 to enable the control of the focus servo.

Abstract: An optical pickup converts a laser beam from a semiconductor laser (1) into a parallel ray with a collimator lens (2), and divides it into a main beam (30), a sub-beam (+1st order component) (31), and a sub-beam (?1st order component) (32) with a gradient multiple-division type phase difference grating (3). After passing through a beam splitter (4), an objective lens (5) condenses the light beams on a track (61) of an optical disc (6), and the reflected light that has passed through the objective lens 5 is reflected at the beam splitter (4) and is guided into optical detectors (8A, 8B, and 8C) by a condensing lens (7). Accordingly, in a tracking error signal detecting method using the push-pull signals of the main beam and sub-beams, an offset produced by an objective lens shift or a disc tilt can be cancelled at low cost without lowering the efficiency of using light.

Abstract: The present invention relates to an optical pickup, and more particularly to an optical pickup comprising an optical modulator for reflecting and diffracting an incident light beam to generate multiple beams, and the optical pickup simultaneously reads a plurality of data bits using multiple beams at the time of reading optical disc information, thus promptly processing optical disk information, thereby the optical pickup of the present invention can cope with various types of optical disk media using light beams with different wavelengths.

Abstract: A recording apparatus and method for recording a mark on a recordable recording medium includes an optical pickup having a light source and an objective lens for focusing light emitted from the light source as a light spot on a recording surface of a recording medium. When recording on a rewritable recording medium, the size of the light spot formed on the recording surface of a recording medium is increased more than when recording on a write once recording medium and/or reproducing from a recording medium. Accordingly, when recording on a rewritable recording medium, the size of a light spot is enlarged more than when recording on an only once writable recoding medium and/or reproducing from a recording medium. Thus, when a mark is recorded on the rewritable recording medium, the erasing rate of an existing recorded phase-change mark is increased to improve the overwriting characteristics.

Abstract: An optical scanning device (1) for scanning three information layer (2, 2?, 2?) with three respective radiation beams (4, 4?, 4?) having three respective wavelengths (?1, ?2, ?3) and polarizations (p1, p2, p3). The three wavelengths differ from each other. At least one of the three polarizations differs from the others. The device comprises a diffractive part (24) including a pattern of pattern elements which have one stepped profile for forming three diffracted beams (15, 15?, 15?) from the three radiation beams, the part comprising birefringent material, sensitive to the three polarizations. The stepped profile is designed such that the heights (hj) of the steps of a pattern element introduce phase changes that equal at least two different multiples of 2? for one (?1) of the three wavelengths and equal at least two different phase changes modulo 2? for one (?2) of the two other wavelengths.

Abstract: The present invention relates to an optical device which includes a first laser diode, a beam splitter, a first objective lens, a photo-detector, a second laser diode, a wedged plate beam splitter, a second objective lens and a collimator. The present invention deploys two independent transmitting paths. The retrieving paths share the beam splitter and the photo-detector commonly at the returning route.

Abstract: A tilt servo control device of an apparatus for recording information on and reproducing information from an optical recording medium set in the apparatus, the apparatus comprising an optical system for leading a laser beam emitted from a light source to a recording surface of the optical recording medium and a laser beam reflected by the recording surface of the recording medium to a photo detector and a read signal generator for generating a read signal in accordance with an output signal of the photo detector. The tilt servo control device determines a type of the optical recording medium, generates a tilt drive signal so as to reduce a tilt angle at a position of the laser beam irradiating the recording surface and an optical axis of the laser beam by a method for generating a tilt drive signal corresponding to the recording medium type, and drives a tilt angle adjuster for adjusting the tilt angle in accordance with the tilt drive signal.

Abstract: An optical disc apparatus for recording, reproducing or erasing an information signal by converging a light flux onto a recording layer through a transparent substrate. The apparatus includes one or a plurality of optical heads having a plurality of objective lenses whose aberrations have respectively been corrected for a plurality of disc substrates of different thicknesses, a cartridge for enclosing the optical disc, a discrimination hole which is formed on the cartridge, and a sensor for detecting the opening/closing state of the discrimination hole and for generating a discrimination signal. In accordance with the result of the discrimination as to the thickness of the loaded optical disc, the objective lens, in which the occurrence of the aberration is smallest, is used, so that the information signal can preferably be recorded, reproduced or erased onto/from the optical discs having different substrate thicknesses.

Abstract: An optical disc apparatus for recording, reproducing or erasing an information signal by converging a light flux onto a recording layer through a transparent substrate. The apparatus includes one or a plurality of optical heads having a plurality of objective lenses whose aberrations have respectively been corrected for a plurality of disc substrates of different thicknesses, a cartridge for enclosing the optical disc, a discrimination hole which is formed on the cartridge, and a sensor for detecting the opening/closing state of the discrimination hole and for generating a discrimination signal. In accordance with the result of the discrimination as to the thickness of the loaded optical disc, the objective lens, in which the occurrence of the aberration is smallest, is used, so that the information signal can preferably be recorded, reproduced or erased onto/from the optical discs having different substrate thicknesses.

Abstract: An optical disc apparatus for recording, reproducing or erasing an information signal by converging a light flux onto a recording layer through a transparent substrate. The apparatus includes one or a plurality of optical heads having a plurality of objective lenses whose aberrations have respectively been corrected for a plurality of disc substrates of different thicknesses, a cartridge for enclosing the optical disc, a discrimination hole which is formed on the cartridge, and a sensor for detecting the opening/closing state of the discrimination hole and for generating a discrimination signal. In accordance with the result of the discrimination as to the thickness of the loaded optical disc, the objective lens, in which the occurrence of the aberration is smallest, is used, so that the information signal can preferably be recorded, reproduced or erased onto/from the optical discs having different substrate thicknesses.

Abstract: An optical disc apparatus for recording, reproducing or erasing an information signal by converging a light flux onto a recording layer through a transparent substrate. The apparatus includes one or a plurality of optical heads having a plurality of objective lenses whose aberations have respectivley been corrected for a plurality of disc substrates of different thicknesses, a cartridge for enclosing the optical disc, a discrimination hole which is formed on the cartridge, and a sensor for detecting the opening/ closing state of the discrimination hole and for generating a discrimination signal. In accordance with the result of the discrimination as to the thickness of the loaded optical disc, the objective lens, in which the occurrence of the aberration is smallest, is used, so that the information signal can preferably be recorded, reproduced or erased onto/from the optical discs having different substrate thicknesses.