Abstract: The present invention can simplify the configuration of a polarization adjustment plate. According to the present invention, the crystal axis of the polarization adjustment wavelength plate 32 is so arranged as to be turned up from the X-Y plane being an orthogonal plane with respect to the optical axis 40a, and the wavelength dependence which the crystal material is originally provided with is largely expressed, and further the thickness “ta” with respect to the optical axis 40a is set up such that the phase difference ? to be brought about at the beam center becomes low from 360°+180°=540° being a desired design value to irradiate the optical beam as the P-polarization by a predetermined difference value or 60°.

Abstract: There is provided an inexpensive optical pickup device that is capable of accurately detecting light quantities of output laser beams on occasion of at least either of reproduction and recording on an information recording medium. A beam from a first light source 1 which beam does not pass through a wavelength selection film 6 of a light separation element 7 is reflected by a first reflection film 10 in a direction to an optical monitor 5. A beam from a second light source 2 which beam does not pass through the wavelength selection film 6 of the light separation element 7 is reflected by a second reflection film 11 in a direction to the optical monitor 5.

Abstract: The present invention aims to provide an optical head and an optical disk device capable of suitably detecting tracking error signals for different types of optical discs. A polarizing hologram element includes a first area and a second area adjacent to the first area in an area where a beam reflected and diffracted by a BD passes. The first area includes a first transmission area for transmitting many 1st-order diffracted lights from the BD, a second transmission area adjacent to the first transmission area and closer to an optical axis than the first transmission area, and a third transmission area adjacent to the first and second transmission areas. The second area includes a fourth transmission area for transmitting many 1st-order diffracted lights from the BD, a fifth transmission area adjacent to the fourth transmission area and closer to the optical axis than the fourth transmission area, and a sixth transmission area adjacent to the fourth and fifth transmission areas.

Abstract: An optical pickup device having an optical module provided with an optical element and bonded and fixed to an optical pickup case, wherein the optical module is fixed to the optical pickup case by a first ultraviolet curing adhesive at at least two positions with an optical axis between the positions, the optical axis extending from the optical element to the optical pickup case, and at least a part of an exposed surface of the first ultraviolet curing adhesive is covered with a second ultraviolet curing adhesive higher in hardness or elastic modulus than the first ultraviolet curing adhesive to diminish an optical axis offset of the optical pickup device, further, a heat dissipating material higher in thermal conductivity than the first and second ultraviolet curing adhesives is brought into contact with both optical module and optical pickup case to improve the heat dissipating performance of the optical pickup device.

Abstract: A method for designing an optical pickup is provided. The optical pick includes a monolithic laser diode that emits a laser light beam for DVD recording and a laser light beam for CD playback, two photodetective portions, and an objective lens, for each of the emitting portions of the monolithic laser diode for emitting the DVD recording and CD playback laser light beams respectively, the specification of the error of the emission direction thereof is determined according to the following formula: |(???1×??1×Dpd1/Dob1????2×??2×Dpd2/Dob2)×Kpd2|??, where, “1” corresponds to the DVD recording laser light beam and “2” corresponds to the CD playback laser light beam, ??? represents the emission angle; ?? represents the sensitivity; Dob represents the diameter of the light beam; Dpd represents the diameter of the spot formed by the light beam; Kpd represents the sensitivity; and ? represents the tolerable value.

Abstract: A lens driving device according to the present invention includes a mounting base; a collimation lens that is engaged with the mounting base and movable in optical axis directions; and a driving source that moves the collimation lens in the optical axis directions, and the mounting base includes a fulcrum section with which, when the driving device is mounted on a base, a pitch angle and a roll angle of the driving device are adjusted with respect to the base and the optical axis.

Abstract: A device for reading from or writing to optical recording media having an optical assembly and a laser diode coupled thereto is described. The laser diode is a twin laser diode which is coupled to the optical assembly by means of a translationally displaceable rotary joint.

Abstract: When the tilt of an optical disk is detected using a light source of an optical head, the optical head cannot be simplified enough and an optical-disk tilt cannot be detected adequately. The optical head includes: an LED chip; a light-converging element that converges the light which is emitted from the LED chip upon an optical disk; a light-converging element driving means which drives the light-converging element; and a sensor which detects a tilt or a positional shift of the optical disk. In the sensor, the LED chip is placed on a semiconductor substrate which is provided with a plurality of light-receiving chips; the light emitted from the LED chip irradiates the optical disk; the light which is reflected from the optical disk is received by the plurality of light-receiving chips; and based upon the quantity of light which is received at the plurality of light-receiving chips, a tilt or a positional shift of the optical disk is detected.

Abstract: In an integrated optical unit of the present invention, a photo detector (12) and a holding member (17) that sustains a semiconductor laser (11) are provided on a polarizing beam splitter (14). This makes it possible to reduce a deviation from a designed value due to tolerance, and adjust a relative positional relationship between the semiconductor laser (11) and the photo detector (12). Therefore, returned light from an optical disk (4) is accurately adjusted with respect to a division line of a photo-detecting device (13). As a result, stable servo-control is realized, and an information signal with fine quality is obtained.

Abstract: An optical pickup and an optical disk apparatus of the invention includes a light source 1 mounted with a light-emitting element constituted of a monoblock on a surface of a plate 6 and emitting plural light beams, a light-receiving element 2, optical members 4, 5 and a coupling base 3 for coupling the light source 1, the light-receiving element 2 and the optical members 4, 5, wherein a light from the light source 1 is directed through the optical members 4, 5 toward an optical disk, and a returning light from the optical disk is guided through the optical members 4, 5 to the light-receiving element 2, characterized in that the plate 6 provided in the light source 1 and the coupling base 3 are adjoined by a solder.

Abstract: An optical system and an information apparatus using the optical system are provided. The optical system includes an optical bench on which a light source and a photodetector including a main photodetector receiving the light are mounted. A lens unit is coupled to the optical bench, and an optical path separating member separates an optical path of light emitted from the light source and propagating toward the lens unit and an optical path of light incident from the lens unit. The optical system may include a monitor photodetector and/or an optical path forming unit coupled to the optical bench. The monitor photodetector receives a portion of the light emitted from the light source. The optical path forming unit includes a first mirror reflecting the light emitted from the light source and a second mirror reflecting the light incident from the lens unit and reflected by the first mirror.

Abstract: An optical information apparatus of the present invention includes: an optical pick-up head including: a light source; a diffraction unit; a condensing unit; a beam splitter; a photodetector; and a tracking error signal generator. An optical recording medium has tracks arranged substantially at a constant pitch. An average of a pitch is tp. When a main beam is placed on the track, a first sub-beam and a second sub-beam are placed between the tracks.

Abstract: A suspension board with circuit includes a metal supporting board, an insulating base layer formed on the metal supporting board, a conductive pattern formed on the insulating base layer, an insulating cover layer formed on the insulating base layer so as to cover the conductive pattern, and an optical waveguide.

Abstract: A slim optical pickup in which a leaf spring is combined with an upper surface of a semiconductor substrate, which is a silicon optical bench (SiOB) monolithically manufactured with a photodetector. The slim optical pickup has a substrate including a light source for generating a light beam, an optical element to irradiate light to an optical disc, a photodetector for receiving a light beam reflected by the optical disc, and a plurality of first bonding pads; a heat sink attached to the surface of the substrate; and a supporting means having a plurality of second bonding pads formed on an inner side of an array of the plurality of the first bonding pads on the substrate.

Abstract: An object lens unit for an optical pickup device is disclosed. The object lens unit includes a first optical element facing an optical information recording medium; a second optical element positioned on a light source side of the first optical element; and a frame in which the first optical element and the second optical element are fixed. The frame includes a first fitting portion and a second fitting portion, and has a prescribed clearance in a perpendicular direction to the optical axis between at least one of the first fitting portion of the frame and the first optical element, and the second fitting portion of the frame and the second optical element to adjust a position of at least one of the first optical element and the second optical element in a perpendicular direction to the optical axis. An optical pickup device including such object lens unit is also disclosed.

Abstract: First, second, and third lead-out conductors connected to the electrodes of two types of laser emission devices of an optical pickup are led out on a lead-out board. First connection areas short-circuit by solder at a portion of opposing parts of any two adjacent lead-out conductors of the first, second, and third lead-out conductors in the width direction crossing the longitudinal direction and open the short circuit, and second connection areas short-circuit by solder at a portion of opposing parts of the other pair of two adjacent lead-out conductors of the first, second, and third lead-out conductors in the width direction crossing the longitudinal direction and open the short circuit. The first connection areas and the second connection areas are arranged in a staggered pattern in the longitudinal direction of the lead-out conductors.

Abstract: In an optical head, if a lens is reduced in size so that it can be integrated with a light source and a photodetector, other optical components as well as the lens must be reduced in size, which would result in greater difficulties in handling for assembly and adjustment purposes. The invention allows large quantities of ultra-small optical heads to be produced accurately and at low cost, the optical heads being easy to adjust and not requiring the handling of minute components for adjustment purposes. A first substrate includes lenses for focusing light on an information storage medium, a second substrate includes detectors and disposed on the surface thereof, and a layer, which is disposed between the first and second substrates, includes prisms and mirrors. The layer also includes cavities in which light sources are disposed. The individual substrates are formed in the form of wafers with the lenses, mirrors, prisms, light sources, and photodetectors disposed thereon.

Abstract: A processing circuit for optical data is provided. The processing circuit includes a signal-processing module and a radio frequency (RF) signal-summing module. The signal-processing module averages and filters the data signals to obtain a low-frequency signal. The RF signal-summing module receives the data signals and the low-frequency signal, sums the data signals to obtain a summed data signal, and subtracts the low-frequency signal from the summed data signal to obtain a RF summing signal.

Abstract: When tracking a dual-layer optical disc by a differential push-pull method, the adverse effect of the reflected light from an adjacent layer, which produces stray light, on a tracking control signal is prevented. A split wavelength plate 20 is inserted in the optical path of the reflected light from the optical disc including the stray light from the adjacent layer so as to detect a region having no interference with the stray light with a four-quadrant detector, and then a push-pull signal by a sub-beam is formed.

Abstract: A multiplexing optical system includes collimator lenses, a first condensing lens, a second condensing lens and an optical fiber. The collimator lenses collimate divergent laser beams that have been emitted from semiconductor lasers. The first condensing lens condenses laser beams transmitted through the collimator lenses in only one of a plane including the stripe width direction of the semiconductor lasers and a plane including a direction perpendicular to the stripe width direction. The second condensing lens condenses laser beams transmitted through the first condensing lens. The optical fiber is arranged in such a manner that the condensed laser beams enter the optical fiber. In the multiplexing optical system, an anamorphic lens is used as the second condensing lens, and the anamorphic lens condenses the laser beams in the two planes in cooperation with the first condensing lens.

Abstract: An optical pickup and an optical recording and/or reproducing apparatus using the optical pickup are provided. The optical pickup includes: a light source; an optical bench on which the light source is mounted; a focusing member including an objective lens, focusing light emitted from the light source to form a light spot on an optical information storage medium; and an optical path forming member having a transparent block that includes a light entrance/exit surface on which the optical bench and the focusing member are arranged, a first reflection surface, and a second reflection surface opposing the first reflection surface, where the optical path forming member directs the light emitted from the light source toward the objective lens by reflecting the light emitted from the light source on the first and second reflection surfaces. The optical pickup satisfies the requirement for smaller, slimmer design and can be integrated using semiconductor manufacturing processes.

Abstract: An integrated optical head is provided. In the integrated optical head, a light source emits light. A waveguide guides the light. An input coupler is located at one edge of the waveguide, and couples light emitted from the light source and transmits the coupled light to the waveguide. An output coupler is located at another edge of the waveguide, and couples light emitted from the waveguide and focuses the coupled light on an optical disc. A light path changing unit is installed on the waveguide, and changes the light path of light that has been reflected by the optical disc and then passed through the output coupler. An optical detector receives the light passed through the light path changing unit and converts the received light into an electrical signal in order to detect information from the optical disc. Accordingly, an input coupling efficiency and an output coupling efficiency are improved, such that light loss is reduced.

Abstract: A semiconductor laser apparatus is provided which comprises a semiconductor laser device for emitting laser light and a base having a major surface and a circumferential side surface. The circumferential side surface has an upper surface and a lower surface. The semiconductor laser device is mounted on the major surface of the base. At least one of the upper and lower surfaces of the circumferential side surface is tilted from a direction perpendicular to the major surface so that a height in a vertical direction of the semiconductor laser apparatus is reduced or minimized.

Abstract: An optical device wherein an optical component and a plurality of light emitting elements are mounted on an identical substrate, a level of a surface on which the optical component is mounted is different from that of a surface on which the light emitting elements are mounted by a step provided on the substrate, at least one plane vertical to the surface on which the optical component is mounted and located on a periphery of the substrate is opened, a reflecting surface, a transmitting surface or a diffraction grating surface of the optical component is provided along sides generated by the step provided in the substrate, optical axes of the plurality of light emitting elements of which polarization axes are in parallel with each other intersect with each other on the surface, and an exit light beam of the light emitting elements is emitted from the opened plane.

Abstract: The magnitude (Ga) of an impact applied to a lens holder is constantly monitored based on an output of an impact sensor. When it is determined that Ga exceeds Gth, focus servo is released, and the lens holder is provided with a force to make it move away from a disk. Upon recheck of Ga, when it is determined that Ga is now equal to or less than Gth, the force having been provided to the lens holder is cancelled, and the focus servo is resumed.

Abstract: A molded coil device includes a coil comprised of a plurality of turns of a conductive material through a plurality of planes and an integral body comprised of an insulating and nonmagnetic material burying the coil. The coil is first formed and thereafter is sintered/pressed with the insulating and nonmagnetic material to form the integral body. The molded coil device is advantageously applied within an optical pickup actuator of an optical disc drive.

Abstract: An optical device diffracts incident light with a hologram element 19 and receives the diffracted light with light receiving regions 20A to 29 on a light receiving element 12. The light receiving element 12 separately receives reflected main beams used to read information from an optical disc and reflected sub-beams used for a tracking operation with different ones of the light receiving regions. The light receiving regions to receive the reflected main beams are common irrespective of the wavelengths of the reflected main beams. The light receiving regions to receive the reflected sub-beams are different depending on the wavelengths of the reflected sub-beams. The optical device can record and/or reproduce information signals to and/or from optical discs, which need light sources of different wavelengths, without the influence of unnecessary reflected light from the optical discs or without complicating operation of output signals.

Abstract: An integrated unit in which a light source and a light emitting diode are combined into one component is fixed to an optical bench. Then, relative position adjustment of an objective lens actuator is carried out with respect to the optical bench so that a desired detection signal can be obtained through reflected light from a disk information recording medium and then the objective lens actuator is fixed. The relative position adjustment of the integrated unit is no longer required and it is no longer necessary preliminarily to provide a margin for adjusting the integrated unit. Thus, an optical head can be reduced in size and thickness.

Abstract: An optical pickup for reading information written on an optical disk is equipped with a laser diode having a front facet which emits light, a parallel light ray portion which collimates the emitted light from the laser diode, means for focusing collimated output light onto the optical disk, means for receiving reflected light from the optical disk, and an optical element having an index of refraction of 1 or higher for adjusting the length of the optical path between the front facet of the laser diode and the optical disk, wherein the optical element is inserted in the parallel light ray portion when the optical path length lies within the range of the expression“(n?0.5±0.25)×the effective cavity length of the laser diode” (where n is a positive integer) in order to reduce the noise in the emitted light of the laser diode.

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: An optical head has a first propagation section made of a first low extinction material and installed along an optical axis, a pair of second propagation sections which, being made of a second low extinction material, sandwich the first propagation section, a pair of first confining sections which, being made of a material with propagation capability lower than that of the second propagation sections, further sandwich the first propagation section and second propagation sections from outside the second propagation sections, and a pair of third propagation sections which, being made of a material with light propagation capability higher than that of the first confining sections, further sandwich the first confining sections from outside. Also, an optical head design apparatus calculates a complex propagation constant along an optical axis by solving an equation which is based on F matrices, and thereby design an optical head in a far-sighted manner.

Abstract: An integrated optical pickup and a manufacturing method thereof, and an optical information storage system including the pickup.

Abstract: The present invention relates to an optical pickup and a disc drive for preventing aberrations of laser light due to variations in temperature and humidity to ensure satisfactory characteristics of the laser light. A compound lens (14) is disposed in the optical path of the laser light, which is emitted by a light-emitting device (11) to be incident on a beam splitter (15), and in the optical path of the laser light, which exits from the beam splitter to be incident on a photodetector (13). The compound lens includes a diffractive section (23) for diffracting the laser light and a lens section (24) having a predetermined function for the laser light. The compound lens is formed by integrating individual sections including the diffractive section and the lens section. The compound lens is provided with a passage hole (14c) that lets in the laser light emitted by the light-emitting device to be incident on the beam splitter.

Abstract: The present invention is an optical pick-up system for use in an optical disk device including more efficient beam diffraction for tracking purposes. The system may be used for one or more types of optical disks (e.g., DVDs, CDs, CD-ROMs). The invention includes a system for use in a DVD player; however, the present invention is applicable to any optical disk device. The system invention includes a gray-scale grating, which provides more efficient diffraction of tracking and processing portions of the laser(s) used in optical disk devices.

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 power control device of single base power is provided for an optical read/write module of an optical disk drive. The optical read/write module generates a power feedback signal and a temperature signal. The power control device includes a current compensating module, a current computing module and a current integrating module. The current compensating module generates an operating current compensating signal and a threshold compensating signal according to the power feedback signal, the temperature signal, a base power signal and a function relationship between the temperature signal and the threshold current of the optical read/write module. The current computing module receives the operating current compensating signal to compute a first operating current signal and a second operating current signal based on the operating current compensating signal according to the base power signal and a reference power signal.

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: An integrated unit in which a light source and a light emitting diode are combined into one component is fixed to an optical bench. Then, relative position adjustment of an objective lens actuator is carried out with respect to the optical bench so that a desired detection signal can be obtained through reflected light from a disk information recording medium and then the objective lens actuator is fixed. The relative position adjustment of the integrated unit is no longer required and it is no longer necessary preliminarily to provide a margin for adjusting the integrated unit. Thus, an optical head can be reduced in size and thickness.

Abstract: A device capable of detecting vibration/shock includes a laser diode capable of transmitting a laser beam and a vibration/shock detector capable of detecting vibration or shock, wherein the laser diode and the vibration/shock detector are formed on one chip.

Abstract: An optical bench is provided, as are a thin optical pickup that employs the optical bench, and a method of manufacturing the optical bench. The optical bench includes a light source for generating light for recording and reproducing information to and from an optical disc, a light source stand on which the light source is mounted, a mirror adjacent to the light source stand, and a bottom surface at a lower point than the light source stand and between the light source stand and the mirror surface. Sides of the light source stand besides the side facing the mirror are connected to the surface of the substrate by a flat sloped surface. Along the sloped surface, two electrodes for supplying power to the light source are connected to the light source stand. Since the metal wirings are formed along the sloped surface without trenches or windings between the light source stand and the silicon substrate, no disconnection of metal lines at a corner occurs.

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 objective lens for converging light onto an information recording medium includes a refracting interface for converging an incident light into a convergent light, and a refractive index varying member disposed between the refracting interface and the information recording medium, and having a refractive index that is varied according to an externally applied voltage.

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.

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: Small-sized and light-weighted optical pickup apparatus capable of eliminating the effect due to the flaring light rays and performing the signal detection of high reliability is provided. In the apparatus, the quarter-wave (?/4) plate and the reflection-type birefringent prime provided with the deflecting function of deflecting the reflection light rays reflected on the optical information recording medium and the light rays flux separating function of separating the reflected light rays from the outgoing light rays are disposed in the optical path between the semiconductor laser constructing the optical pickup portion and the objective lens, and the light-receiving element for receiving the reflection light rays from the optical information recording medium which are defleced and separated by the reflection-type birefringent prism is disposed on a single (same) substrate together with the semiconductor laser.

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.