Abstract: A beam shaping optical system which is provided with a first wedge prism having two refractive surfaces defining a first principal section, and a second wedge prism having two refractive surfaces defining a second principal section that is parallel to the first principal section, wherein a reference ray of light forms incident angles at each of the refractive surfaces of the prisms satisfying the following condition (1): ##EQU1##

Abstract: A semiconductor laser device is mounted on the side of one end surface on lead frame in a recess of an insulating molding member, a three-beam generating diffraction grating is disposed in the center, and a transmission type holographic optical element is disposed on the side of the other end surface. After a flexible circuit board is fixed to the lower surfaces of leads and the lead frame, a photodiode for a signal detection is mounted on the surface of the flexible circuit board, and is so folded upward as to be perpendicular to the upper surface of the lead frame. The insulating molding member is mounted on the one end surface of the insulating molding member through a circular screw through a hole and an elliptic screw through a hole by screws.

Abstract: Digital data bits are stored as discrete-level reflection microholograms in a multi-depth digital optical data storage system. Reference and signal beams are incident in a counterpropagating geometry on opposite faces of a tape. The reflection microholograms are stored at the coinciding focus of the reference and signal beams. The holograms are stored at the diffraction limit of high-N.A. optics, and have relatively high grating frequencies and small sizes. Dynamic aberration compensators correct for the depth-varying spherical aberration imparted to the beams by the medium. Multiple mutually-incoherent lasers are used for parallel storage and retrieval to increase data transfer rates. Achievable densities and signal-to-noise ratios are substantially higher than for index-perturbation or transmission hologram storage methods.

Abstract: An optical pickup which can be employed for different formats of a disk recording medium is disclosed. The optical pickup device includes a light source including first and second vertical cavity surface emitting lasers closely disposed to each other for emitting light having different wavelengths and different radiation angles, an objective lens for focusing the light emitted from the light source on a recording surface of a recording medium, a photodetector for detecting information signals and error signals by receiving the light reflected from the recording medium, a polarized beam splitter disposed on an optical path between the light source and the objective lens to redirect a proceeding path of incident light, and a wavelength plate disposed on the optical path between the objective lens and the polarized beam splitter to convert a polarization component of incident light.

Abstract: A semiconductor light emitting device comprises: a compound semiconductor substrate; an n-type cladding layer on the compound semiconductor substrate; an active layer on the n-type cladding layer; a p-type cladding layer on the active layer: and a p-type contact layer on the p-type cladding layer, the n-type cladding layer, the active layer, the p-type cladding layer and the p-type contact layer being made of II-VI compound semiconductors containing at least one of group II elements selected from the group consisting of Zn, Cd, Mg, Hg and Be and at least one of group VI elements selected from the group consisting of S, Se, Te and O, characterized in that at least the active layer has undulations and at least the p-type layer is flat.

Abstract: An integrated optical head, such as, for a disk drive, preferably includes an optically transparent substrate. The substrate has a diffractive optical element formed on one face and a plurality of electrical contact pads exposed on the other face. A light source is positioned to emit light through the substrate, through the diffractive optical element, and toward data storage media. The light source includes a plurality of electrical contact pads corresponding to the plurality of electrical contact-pads exposed on the face of the substrate. An optical detector is positioned to detect light reflected from the data storage media, through the diffractive optical element, and through the substrate. The optical detector includes a plurality of exposed electrical contact pads corresponding to the plurality of electrical contact pads exposed on the face of the substrate. The substrate and the light source and optical detector are passively aligned using solder bumps between pairs of contact pads.

Abstract: An apparatus for changing the phase of an optical storage medium changeable between a reflective phase and a dispersive phase. The apparatus including a quasi-multimode vertical cavity surface emitting laser constructed to provide a laser beam in a square shaped mode, to be directed onto the storage medium.

Abstract: An optical pickup irradiates a record surface of an optical storage medium with light and receives the light reflected by the record surface. The reflected light includes a data signal light corresponding to data recorded on the optical storage medium and other light. The optical pickup comprises a light source, a data photo detector, another photo detector, a base, a beam splitter, an introductive optical element, and a lens. The light source emits the light to the record surface. The data photo detector receives the data signal light. The another photo detector receives the other light. On the base, the light source, the data photo detector and the another photo detector are arranged. The beam splitter transmits the light from the light source and separates the reflected light from the optical record medium into the data signal light and the other light. The introductive optical element introduces the data signal light to the data photo detector and the other light to the another photo detector.

Abstract: An integrated optical head, such as, for a disk drive, preferably includes an optically transparent substrate. The substrate has a diffractive optical element formed on one face and a plurality of electrical contact pads exposed on the other face. A light source is positioned to emit light through the substrate, through the diffractive optical element, and toward data storage media. The light source includes a plurality of electrical contact pads corresponding to the plurality of electrical contact pads exposed on the face of the substrate. An optical detector is positioned to detect light reflected from the data storage media, through the diffractive optical element, and through the substrate. The optical detector includes a plurality of exposed electrical contact pads corresponding to the plurality of electrical contact pads exposed on the face of the substrate. The substrate and the light source and optical detector are passively aligned using solder bumps between pairs of contact pads.

Abstract: A laser light detect/emit package 3 and a biaxial drive portion 5 for driving the objective lens 4 are supported on a wiring board 1 having wiring patterns 2a and 2b to electrically connect them to the wiring patterns 2a and 2b. Packaged in the laser light detect/emit package 3 are a laser coupler 11 having an optical prism 15 and a laser chip 16 formed on a photo diode IC 14 including photo diodes 12 and 13 for detecting optical signals. In lieu of the laser light detect/emit package 3, an auxiliary wiring board supporting the laser coupler 11 may be inserted and held in a recess formed in the wiring board 1.

Abstract: An integrated vertical cavity surface emitting laser (VCSEL) pair for use in an optical pickup head for high density optical storage applications and a method of fabrication. The VCSEL pair includes a high power VCSEL capable of emitting a power output of at least 15 mW and a low power VCSEL capable of emitting a power output in a range of 1-4 mW. A phase shift mask is integrated with the high power VCSEL to allow for a 180.degree. shift in light emitted therethrough, thereby creating a reduced focal spot size for high density data write applications. The low power VCSEL emission is focused into a Gaussian beam profile for data read applications. The integrated VCSEL pair is utilized in an optical pickup head capable of high density read and write applications for both CDs and DVDs.

Abstract: A semiconductor light amplifier device emits, from an exit end processed to yield no reflection, outgoing light with a light quantity corresponding to a driving signal input from a driving circuit. This outgoing light irradiates, by way of an optical system, an object to be measured; whereas the reflected light, scattered light, and diffracted light generated by the object trace back the optical system and are made incident on the exit end of the semiconductor light amplifier device in a feedback manner as return light. Accordingly, the light amplifier device performs optical amplification as the return light is incident thereon, thereby increasing the light quantity of the outgoing light. This change in light quantity of the outgoing light is detected by the light-receiving device and output therefrom as a light-receiving signal.

Abstract: An optical device comprises a substrate, a light-emitting portion, and a plurality of light-receiving portions, the light-emitting portion and a plurality of light-receiving portions being closely laminated on the same substrate, wherein returned light obtained after light emitted from a resonator end face of the light-emitting portion has been reflected on an irradiated portion is received and detected near a confocal point by a plurality of light-receiving portions. In this optical device such as an optical pickup, the number of optical ssemblies can be reduced, an alignment for disposing optical assemblies can be simplified, the whole of the optical device can be simplified and miniaturized, and a stable tracking servo can be effected by effectively utilizing advantages of a push-pull method.

Abstract: A magneto-optical pick-up for recording and reproducing information to an information recording medium comprises an optical module comprising an integral light emitting element and receptor element having plural light reception areas, and a diffraction grating on the light incident/emission plane, an objective lens, a polarizing prism provided integrally to the optical module in the light path between the light-emitting element and an objective lens and having the reflectivity and transmittance differing for P-polarized and S-polarized lights, and a polarizing element provided internally or integrally to the optical module which divides the light reflected by or passed through the polarizing prism into light having at least two mutually-perpendicular polarization components to guide the divided lights to the receptor element.

Abstract: An integrated optical head, such as, for a disk drive, preferably includes an optically transparent substrate. The substrate has a diffractive optical element formed on one face and a plurality of electrical contact pads exposed on the other face. A light source is positioned to emit light through the substrate, through the diffractive optical element, and toward data storage media. The light source includes a plurality of electrical contact pads corresponding to the plurality of electrical contact pads exposed on the face of the substrate. An optical detector is positioned to detect light reflected from the data storage media, through the diffractive optical element, and through the substrate. The optical detector includes a plurality of exposed electrical contact pads corresponding to the plurality of electrical contact pads exposed on the face of the substrate. The substrate and the light source and optical detector are passively aligned using solder bumps between pairs of contact pads.

Abstract: An optical pickup device for irradiating a laser beam onto an optical recording medium and receiving a return light from the optical recording medium, comprising a semiconductor laser element which is formed on a semiconductor substrate and has first and second light emitting faces, a first reflection portion provided so as to confront the first light emitting face of the semiconductor laser element, a second reflection portion provided so as to provide confront the second light emitting face of the semiconductor laser element, a first photodetector for receiving a return reflection light of the laser beam which is reflected from the first reflection portion and focused on the recording medium, and a second photodetector for receiving a return reflection light of the laser beam which is reflected from the second reflection portion and focused on the recording medium. A recording signal on the recording medium and a focus error signal are detected by the first and second photodetectors.

Abstract: The optical head is arranged such that a semiconductor laser and a photodetector are formed via a buffer layer on the same substrate; and an opening portion is formed in the substrate under the semiconductor laser and the photodetector. This optical head is further arranged by that the opening portion is filled with a first transparent layer; a diffraction grating is formed on a lower surface of the first transparent layer; a second transparent layer is stacked on a lower surface of the first transparent layer; and a condenser lens is formed on a lower surface of the transparent layer.

Abstract: An optical unit includes a first holder with a radiation source, a second holder with a radiation-sensitive detector, a grating, and a mirror. The unit further includes a cylindrical mounting having a cylinder axis and a wall oriented transversely to the cylinder axis, the grating and the mirror being formed by optically transparent wall portions of the wall. The mounting has a first positioning surface to which the first holder with the radiation source is secured and a second positioning surface to which the second holder with the radiation-sensitive detector is secured.

Abstract: An optical head for a magneto-optical disk drive, including a laser diode mounted on a stem, a magneto-optical signal detector unit, and an error signal detector unit for detecting a focusing error and a tracking error. A cap is mounted on the stem so as to surround the laser diode and these detector units, and a beam splitter unit including a polarization beam splitter and a polarizing prism is mounted on the cap. A hologram for diffracting an error signal beam toward the error signal detector unit is formed on a lower surface of the beam splitter unit.

Abstract: An optical device for detecting a magneto-optical signal can be simplified and miniaturized in arrangement. An optical device for detecting a magneto-optical signal includes an optical element in which a light-emitting portion and a light receiving portion are closely disposed on a common substrate and in which reflected-back light obtained from a magneto-optical medium after light from the light-emitting portion was reflected on the magneto-optical medium is detected at a position near confocal position by the light receiving portion and another light receiving element. The reflected-back light from the magneto-optical medium is divided. One reflected-back light is detected by the light receiving portion of the optical element and the other reflected-back light is detected by another light receiving element.

Abstract: Light is emitted from a light-emitting element toward an irradiated medium, and returning light reflected by the irradiated medium is diffracted by a hologram device. A polarizer polarizes the light diffracted by the hologram device to produce first polarized light that has passed through the polarizer and second polarized light that has been reflected by the polarizer. The first polarized light is detected by a first light-detecting element, and the second polarized light is detected by a second light-detecting element. A magnetooptical signal is generated as the difference between the intensities of the first and second polarized lights which are detected respectively by the first and second light-detecting elements.

Abstract: An optical system including an LDGU having a multi-element grating beam splitter and an optical source with an effective aperture for generating a radiation beam to be applied to a data track of an optical storage medium, an improved LDGU is described. The LDGU includes a baseplate having a plurality of registration pins and defining a plurality of clearance holes; a body having a ring portion which defines a central opening and having a plurality of registration openings; a ceramic header defining alignment openings and having a plurality of contact pins which are aligned to the clearance holes of the baseplate; at least two of the registration pins of the baseplate being aligned in the registration openings in the body and at least two of the registration pins being aligned in the alignment openings in the ceramic header; and a structure for mounting the grating beam splitter and the optical source on the ceramic header.

Abstract: An optical tape including an optical recording layer for permitting information to be optically recorded thereon and a light-reflective magnetic layer; the light-reflective magnetic layer which reflects light projected onto the recording layer, also permits magnetic recording or magneto-optical recording to be performed thereon, thereby increasing a storage capacity of the optical tape remarkably; further, the optical tape is provided with a layer to form guiding grooves for tracking control, which layer to form guiding grooves is made up of ultraviolet-hardening resin, photo-resist, or a photochromic material.

Abstract: A method for controlling intensities of a plurality of laser beams respectively emitted on a track of an optical disk by a plurality of laser diodes according to the present invention includes a step of performing focusing servo control for focusing one of the plurality of laser beams emitted by one of the plurality of laser diodes onto the track, and concurrently controlling an intensity of the laser beam emitted by each of plurality of laser diodes to be within a predetermined range by comparing a signal which is in accordance with an intensity of the laser beam emitted by that laser beam with a reference signal. A period during which the one of the plurality of laser diodes used for the focusing does not emit the one laser beam is shorter than a response time of the focus servo control.

Abstract: There is provided a device for monitoring the light output of a VCSEL and a recording and reproducing optical pick-up adopting the device. The device for monitoring the light output of a VCSEL has a half mirror positioned in front of a VCSEL, for reflecting a portion of the light emitted from the VCSEL, and a monitoring optical detector positioned behind the VCSEL, for detecting the light reflected from the half mirror. The recording and reproducing optical pick-up employing the device includes a VCSEL having a light-emitting surface for emitting light vertically from the light-emitting surface, a light output monitor for monitoring the light output of the VCSEL, an objective lens for concentrating incident light on an optical recording medium to form an optical spot thereon, a light path changer for changing a path of the light reflected from the optical recording medium, and a first optical detector for receiving the reflected light and detecting an error signal and an information signal.

Abstract: A monolithically integrated optical disk pickup head is comprised of three-dimensional collimating focusing lenses, a beam splitter and 45-degree reflectors that define an optical axis in free-space using surface micromachining technology to fabricate hinged vertical optical structures.

Abstract: An apparatus and method are provided for determining the position of a reflective target surface using one or more laser cavities. A transmitting laser cavity produces a stable resonator output beam which is modulated with a compound beam pattern including a first wave of frequency f.sub.1 and a second wave of frequency f.sub.2. The reflected compound modulated beam enters a receiving laser cavity and fundamental and harmonic waves f.sub.1 and f.sub.2 are generated in the receiving laser cavity. The power of the compound modulated output beam of the receiving laser cavity is measured by a photodiode and a deconvolution system is connected to the photodiode for filtering the fundamental frequency of f.sub.1 and the second harmonic of wave f.sub.2. Time-dependent changes in the measured power of the modulated compound output beam are used to derive positional information of the target.

Abstract: An integrated optical pick-up device includes a laser source which emits incoherent laser consist of varied wavelength in wide spectrum, and an optical filter which eliminates improper ranges of the laser's spectrum and transmits only preferred wavelength domains. Therefore, a focus grating which is positioned to intercept the laser can produce several focal points dependent upon selected wavelength by the optical filter. Then another grating deflects each reflected laser from different points on the optical medium at certain angle and transmits to specific photo-detector.

Abstract: Near-field optical apparatus according to the invention contains a novel semiconductor laser photon source. The source is capable of providing substantially higher photon flux than prior art near field sources, potentially facilitating read-out rates in the megahertz range in exemplary near-field data storage and retrieval apparatus. The novel source comprises a non-uniform laser emission face, with the emission face configured such that at least 50% of the total radiation emission is from a small (first) region of the emission face, of width less than .lambda..sub.s /2, where .lambda..sub.s is the emission wavelength of the laser. In an exemplary embodiment, a multilayer coating is provided on the emission face, such that radiation emission from the face is relatively low. A recess is formed in the coating such that substantial radiation emission from the recess occurs. The recess constitutes the first region.

Abstract: An optical pick-up apparatus for reproducing information recorded on a magneto-optical record medium including a semiconductor laser emitting a linearly polarized laser beam, and a polarizing film provided between a glass prism and a uniaxial birefringent crystal prism. The laser beam emitted by the semiconductor laser is made incident upon the polarizing film via the glass prism and is reflected thereby. The apparatus further includes an objective lens projecting the laser beam reflected by the polarizing film onto the magneto-optical record medium as a fine spot and converging a return laser beam reflected by the record medium toward the polarizing film. The return beam transmitted through the polarizing film is refracted by the uniaxial birefringent crystal prism and is divided into ordinary light and extraordinary light, which are received by a first photodetector to produce a reproduced information signal.

Abstract: An optical integrated circuit includes a substrate and a thin film formed on the substrate. A waveguide is formed by the thin film. A grating coupler includes a plurality of coupling regions for introducing an incident light beam into the waveguide, and for separating the incident light beam into output light beams propagated in the waveguide in different directions respectively. The output light beams are in a same waveguide mode and have polarization directions perpendicular to each other respectively. Photodetectors are exposed to the output light beams propagated in the waveguide for detecting the output light beams respectively.

Abstract: There is provided an optical pickup for use with an optical disk, which is capable of detecting tracking error signals and focusing error signals with good precision even when applied to the SCOOP method, and includes a light-emitting device having a light-emitting portion on a substrate for emitting light onto the optical disk, the light reflected by the optical disk being made to return to the light-emitting portion to vary oscillation of the light-emitting portion such that a signal recorded in the optical disk is read on the basis of a variation in the oscillation of the light-emitting portion, wherein an optical path length between the light-emitting device and the optical disk is set such that an interference intensity of interference fringes at a distance twice as large as the optical path length is at most one-tenth as large as a peak value of an interference intensity of interference fringes of a maximum intensity.

Abstract: An optical recording/reproducing apparatus comprises a semiconductor laser having a plurality of radiative portions formed at different heights on a same substrate and a spot forming system for arranging beams from the plurality of radiative portions in the semiconductor laser to form a plurality of light spots on an information recording medium for effecting information record and reproduction. In the apparatus, the spot forming system concurrently forms a first recording light spot and a first reproducing light spot on a first information track on the information recording medium and concurrently forms a second recording light spot and a second reproducing light spot on a second information track different from the first information track on the information recording medium.

Abstract: An optical device for detecting a magneto-optical signal can be simplified and miniaturized in arrangement. An optical device for detecting a magneto-optical signal includes an optical element (101) in which a light-emitting portion (4) and a light-receiving portion (5) are closely disposed on a common substrate and in which reflected-back light obtained from a magneto-optical medium (34) after light emitted from the light-emitting portion (4) was reflected on the magneto-optical medium (34) is detected at a position near confocal position by the light-receiving portion (5). The light-receiving portion (5) on the optical element (1) has a light-receiving surface inclined relative to the optical axis of the reflected-back light formed thereon so that the light-receiving portion has a polarization selective transmittance function on its surface. Thus, the reflected-back light from the magneto-optical medium (34) can be received and detected by the light-receiving portion (5) on the optical element (101).

Abstract: This specification discloses a magneto-optical recording medium in which on the opposite side of a second magnetic layer having a relatively low curie temperature and a relatively great coercive force, there are laminated a first magnetic layer and a third magnetic layer each having a relatively high curie temperature and a relatively small coercive force as compared with the second magnetic layer, the second magnetic layer has its curie temperature varying in the direction of film thickness thereof and has a curie temperature T.sub.L1 near the interface thereof with the first magnetic layer and has a curie temperature T.sub.L3 near the interface thereof with the third magnetic layer, and T.sub.L1 .noteq.T.sub.

Abstract: Not more than one compound holographic optical element is provided on an optical path starting from a semiconductor laser chip and arriving at a photo detector via an optical disk. A hologram pattern of this compound holographic optical element is the superposition of a first hologram pattern, converging a laser beam emitted from the semiconductor laser chip onto the optical disk, and a second hologram pattern, diffracting the laser beam reflected at the optical disk toward the photo detector and changing it into a focusing beam. This single holographic optical element not only realizes the convergence of the laser beam onto the optical disk and/or the photo detector and the differentiation of going and returning optical paths but reduces the size and production cost of the optical pick-up apparatus.

Abstract: An optical device for detecting a magneto-optical signal can be simplified and miniaturized in arrangement. An optical device for detecting a magneto-optical signal includes an optical element in which a light-emitting portion and a light receiving portion are closely disposed on a common substrate and in which reflected-back light obtained from a magneto-optical medium after light from the light-emitting portion was reflected on the magneto-optical medium is detected at a position near confocal position by the light receiving portion and another light receiving element. The reflected-back light from the magneto-optical medium is divided. One reflected-back light is detected by the light receiving portion of the optical element 1 and the other reflected-back light is detected by another light receiving element.

Abstract: The present invention is directed to an apparatus using an integrated type pickup as an optical head for writing and reading optical information and capabling of writing data at high speeds. The apparatus includes a laser diode having an active layer at its intermediate position and having one area side held over a surface of a semiconductor substrate with an insulating layer interposed between the semiconductor substrate and the laser diode relative to the active layer. The laser diode has two areas with the active layer as a boundary and a constant potential is applied from a power supply to the insulating layer side of the laser diode and a transistor (laser diode drive unit) is provided to apply a modulation signal to the other area of the laser diode so that the laser diode is driven to modulate its output.

Abstract: A laser plate making apparatus is disclosed for forming a press plate from a form plate sheet. The apparatus includes a laser light source for providing a laser beam, a collimator lens, an objective lens and an anamorphic prism. The laser light source serves to emit a laser beam onto the form plate sheet through the collimator lens, the objective lens and the anamorphic prism. The anamorphic prism serves to shape the laser beam such that even if a focal stripe width is made small the focal depth is not substantially shortened.

Abstract: An optical head has a semiconductor laser for emitting light, a collimator lens for converting the light from the laser into a parallel light beam, a semiconductor substrate for reflecting the light beam, and an objective lens for focussing the light beam reflected from the substrate on the optical disk. A 1/4 wavelength plate is situated between the substrate and the objective lens. A beam splitter which transmits the light from the laser and reflects the light returning from the disk is provided between the collimator lens and the substrate. Following the beam splitter, a collective lens, a cylindrical lens and an optical detector are arranged in this order on an optical path for the returning light. A light receiving element for outputting a signal corresponding to the intensity of the light received is formed on the semiconductor substrate, and a polarizing film is formed on the surface thereof.

Abstract: Information represented by an arrangement of codes of three or more kinds is recorded on a recording medium having a track in the following manner. The codes of the information are caused to correspond to information pits of three or more kinds respectively. The information pit corresponding to each code is formed on the track so as to be arranged along the track. Each information pit is recognized by the length thereof along the longitudinal direction of the track and the distance between the center of the pit in the longitudinal direction of the track and a reference position determined by a reference clock.

Abstract: There is provided an optical pickup adapted to read out signals recorded in an optical disk, which is capable of detecting tracking error signals and focusing error signals with good precision even when applied to the SCOOP method, and includes at least three light-emitting parts each capable of emitting laser beam, a detection part provided in association with each of the light-emitting parts for detecting a variation of an output in the light-emitting part associated therewith which is caused by the laser beam reflected by the optical disk, a tracking servo mechanism and a focusing servo mechanism, the servo mechanisms being adapted to be driven in response to signals respectively output by the detection parts for correcting a focusing point of the laser beam, wherein the detection parts each connected to a capacitor and an amplifier sequentially, at least two of the detection parts being each further connected to a rectifier after the amplifier to turn each of the signals respectively output by the detecti

Abstract: An electromagnetic radiation read mechanism for reading data stored optically upon an element having a surface and a plurality of tracks, which mechanism includes a source of electromagnetic radiation; an optical coupling system, which optical coupling system is disposed so as to receive radiation output by the source of electromagnetic radiation and spread it into a plane; a prism, which prism is constructed and disposed so as to receive the plane and redirect it to reflect off of the surface of the element, and which prism is further constructed and disposed so as to receive the reflected plane and to redirect it outward; a multi-element optical sensor, which sensor is disposed so as to receive the redirected reflected plane; and a decoder connected to the multi-element optical sensor so as to receive signals therefrom, which decoder allows parallel data reading of all of the tracks of the element simultaneously.

Abstract: An optical head for optical recording and reproducing apparatuses is disclosed. The optical head comprises a semiconductor laser, a mirror for reflecting a light beam emitted from the semiconductor laser, a diffraction grating for dividing the light beam into zero order, plus and minus first-order beams. It also comprises a holographic diffraction grating being arranged at an optical path of the beams divided by the diffraction grating, an objective lens for focusing the beams on a disk and causing the beams reflected from the disk to be incident on the holographic diffraction grating to diffract the beams, and a photodetector for detecting a tracking error signal by receiving the beams diffracted by the holographic diffraction grating. The semiconductor laser has a beam incident area onto which the beam reflected from the disk is incident. The beam incident area acts to scatter or absorb the incident beam. As a result, the optical head is able to obtain a stable tracking error signal.

Abstract: An optical head of this invention includes: a light source emitting a plurality of beams from a plurality of emitting points; an optical system for focusing the plurality of beams on a recording medium; and an adjusting means for adjusting distances from the plurality of emitting points to the optical system, wherein the adjusting means includes a first member for supporting the light source and a second member for supporting the first member; the first member is rotatable around a central axis which is vertical to the plane including an optical axis of the optical system and the plurality of emitting points and passes through a point on the optical axis; and the second member is movable along a reference plane vertical to the optical axis.

Abstract: An optical disc apparatus, which uses an optical disc having a signal recorded on both hollow and convex portions of tracks, provides stable tracking control. An offset judging circuit judges whether the signal has been recorded only on either of two recording regions adjacent in a vertical direction to the track direction. An offset application circuit applies an offset voltage to an error signal on the basis of a control signal output in accordance with the result of the offset judging means. This effectively cancels an offset in the tracking error signal caused by the existence of recording pits only on an inner circumference side or outer circumference side of an adjacent recording track to provide stable tracking control. Moreover, addresses of presently recorded regions are stored in a recorded address control memory, so that detection that the signal has been recorded on either of two adjacent recording regions can be performed with a simple structure.

Abstract: An optical information reproducing apparatus of the invention includes a light emitting and receiving unit and an optical system. The optical system converges light from the light emitting and receiving unit on a recording medium and converges the light after reflected by the recording medium. The light emitting and receiving unit includes: a semiconductor laser device disposed on a substrate for generating light; a photo detector formed, integrally with the substrate, on the substrate on which the semiconductor laser device is disposed, for outputting a signal corresponding to the intensity of light incident thereon; and a beam splitter provided on an optical axis of the reflected light, the beam splitter leading part of the reflected light to the photo detector.

Abstract: This invention relates to a light-emitting apparatus, a photosemiconductor apparatus and a method for producing a photosemiconductor wherein the light-emitting apparatus for emitting light on an object comprises a substrate; a light-emitting element provided on the substrate; an optical member provided on a predetermined position to the substrate; a light-receiving element provided on the substrate, the light-receiving element receiving a part of light beam emitted from the light-emitting element on the object via the optical member; and means for controlling a quantity of the beam projected from the light-emitting element on the object, based on an output signal from the light-receiving element.

Abstract: An optical head for writing and/or reading information on and/or from an optical record medium such as a magneto-optical record medium including a semiconductor substrate, a semiconductor laser mounted on a surface of the semiconductor substrate for emitting a laser beam, an objective lens for projecting the laser beam onto the optical record medium as a fine spot, a plurality of photodetectors firmed in the surface of the semiconductor substrate, and an optical block arranged on said semiconductor substrate to form an integral unit together with said semiconductor substrate. The optical block includes a hologram for diffracting a return beam reflected by said magneto-optical record medium and a polarization beam splitting plane arranged in substantially parallel with an optical axis of a zero order beam emanating from the hologram for splitting a pupil of the hologram.

Abstract: A semiconductor laser chip comprises a substrate and material layers successively formed on the substrate. The laser chip has an output cleavage face and emits an output laser beam which is inclined to the output cleavage face. The laser chip may be incorporated in a laser pickup device for optically reading information from an optical data carrier such as optical disk.