Abstract: An optical head device for use in recording and/or reproduction of information comprises a light beam generating portion, a lens element for causing a light beam obtained from the light beam generating portion to impinge upon a record medium and receiving the light beam from the recording medium, and a photodetecting portion to which the light beam from the record medium received by the lens element is guided and which has three photosensitive elements separated from each other by a couple of parallel dividing portions and disposed to form a common light receiving plane on which a beam spot is formed by the light beam guided to the photodetecting portion for detecting the light beam guided to the photodetecting portion to produce respective detection output signals from which a tracking error signal is produced, wherein each of the parallel dividing portions extends along a direction selected to be at an angle within an angle rqnge of 0 to 90 degrees to a direction of movement of a diffraction pattern appeari

Abstract: An optical recording/reproducing module comprises a housing defined with a depression, a focusing actuator provided on one side of the housing for carrying an objective lens such that the lens is movable in a direction perpendicular to the aforementioned one side, an optical system accommodated in the depression, the optical system includes an optical source for producing a first optical beam to be directed to the objective lens, an optical detector for detecting a second optical beam received by the objective lens and incident to the optical detector, the optical detector further produces an electrical output signal responsive to the second optical beam, and an array of optical elements for guiding the first optical beam produced by the optical source to the objective lens and for guiding the second optical beam received by the objective lens to the optical detector, a cover lid adapted to be mounted on the one side of the housing, the cover lid has a shape adapted to close the depression, and an electrical

Abstract: An information recording and/or reproducing apparatus in which a beam emitted from a light source is applied to an optical recording medium to thereby record and/or reproduce information thereon has a light projecting device for projecting a medium-detecting-light flux onto the surface of the optical recording medium, a discriminating device for detecting the level of the reflected light or the transmitted light of the medium-detecting-light flux from the optical recording medium and discriminating between optical recording mediums different in characteristic by the detected level, and an intensity changing device for changing the intensity of the beam on the surface of the optical recording medium in accordance with the determination of the discriminating device.

Abstract: The invention comprises an optical pickup apparatus including a photodetector which detects a laser beam reflected from information tracks of a disk and an amplifier circuit which amplifies the outputs of the photodetector. The photodetector and the amplifier circuit are integrally combined. A preamplifier circuit is also provided for positional adjustments. A switch is included within the amplifier for alternately inhibiting the path of the outputs of the photodetector to the amplifier circuit to allow for positional adjustment with the preamplifier and enabling the path of the outputs of the photodetector to the amplifier circuit for normal operation.

Abstract: An optical servo head and method for reading position information on a medium, such as a magnetic disk, having a plurality of optical servo tracks in the form of relatively nonreflective regions on a reflective surface of the medium. With a magnetic disk, the nonreflective regions comprise concentric grooves etched in the disk surface and the reflective regions comprise the land areas between the grooves. The optical servo head is mounted on a carriage/head assembly of a disk drive and comprises an infrared light emitting diode, a collection lens, a routing mirror and a multicell photodetector.

Abstract: An optical disk apparatus comprises an optical pickup having an optical pickup body carrying a laser and a photodetector responsive to light emitted from the laser and reflected by the optical disk for producing tracking error signals mounted on the optical pickup body for reciprocal movement in a tracking direction responsive to operation of an actuator, and supports an objective for focusing the beam on the disk. A position sensor produces position signals in response to displacement of the movable portion in the tracking direction. Finally a servo tracking circuit outputs driving signals to the actuator on the basis of tracking error signals produced either in response to tracking error signals produced from outputs of the photodetector and position signals produced from output signals of the position sensor, in response only to the latter.

Abstract: For use in combination with an optical source for generating a coherent beam along a main optical axis, an optical head device comprises a diffraction grating having a plurality of grating regions which are responsive to the coherent beam for directing a zeroth-order diffracted beam to a focussing lens and are responsive to an optical beaem reflected from an optical recording medium for directing sidewards diffracted beams to an optical detector assembly. An effective area of a diameter of about 5 mm is sufficient for the diffraction grating. Each sidewards diffracted beam may form an angle of 20.degree. with the main optical axis. The optical detector assembly is used in detecting focussing and tracking errors for the recording medium and can be used in reproducing optical information from the recording medium. A six-partitioned optical detector assembly is preferred when the grating regions are four in number.

Abstract: Error correction in a feedback servo system. The feedback servo loop in, for example, a head positioning circuit in an optical disk data recording and retrieval system is provided with means for forcing the feedback signal to zero when the head is positioned at best focus as determined by a peak in the laser monitoring diode. The head in such a system must be dynamically maintained at a best focus position but, through use and transporting, the alignment of the head position error detecting system can be disturbed. In some cases, the loop circuit parameters may drift from their original values. To correct for errors introduced from such causes, the head is positioned at best focus and the focus error (head position error) signal is sensed. A correction system forces the sensed value to zero, e.g, by adjusting the gain of amplifiers used in the feedback loop.

Abstract: In case that the light beam emitted from a light source mounted on a base element is focused to a spot light on a data storage media to write the data, when the light beam reflected from the data storage media to return to the light source is reflected from the base element and focused again on the data storage media, it becomes difficult to precisely read/write the data on the storage media. In order to resolve the above problem, a light beam treating means is provided in the base element to prevent the re-incident light beams from being reflected toward the data storage media and focused thereon.

Abstract: A diffraction grating comprises a birefractive sheet (11) having a corrugated surface with at least each groove filled with a mass (12) of a material of a refractive index which is substantially equal to one of ordinary and extraordinary indices of the birefractive sheet. The diffraction grating is effective in an optical head device when made to have a plurality of grating regions of different patterns of corrugations. In this event, a linearly polarized beam should be supplied to the diffraction grating with electric vectors directed parallel to those of ordinary and extraordinary components when the refractive index is substantially equal to the ordinary and extraordinary indices, respectively. Alternatively, such an optical head device may comprise a reflection grating in which reflective corrugations are substantially parallel in the respective grating regions. In this event, a linearly polarized beam is supplied from an optical source to the reflective corrugations as a p-polarized beam.

Abstract: In an optical storage system where an information bearing surface moves relative to a read/write head the latter includes a transparent body in which light beams sent to and from the surface are guided by multiple internal reflections. Beam shaping and focussing is effected by optical elements integrated in the surface of the body at the locations where the internal reflections occur. A distortion free imaging system is obtained with two series-arranged aspheric reflection surfaces which focus the beam on the information bearing surface. The separation of the input and the reflected beam paths is achieved with a polarizing beam splitter and an associated quarter-wave layer. For readout of a magneto-optic information bearing surface a nonperfect polarizing beam splitter is used in connection with a differential detection scheme to increase the signal to noise/ratio.

Abstract: An apparatus for reproducing data stored on a disc in a plurality of tracks connected in a continuous spiral or separated in concentric tracks.

Abstract: An optical pickup apparatus comprises two photodetectors disposed on one and the same substrate. The light beam from the recording medium is divided into two light components by an optical member and the two light components are guided to the two photodetector positioned on the same substrate.

Abstract: In an apparatus for optically reproducing the recorded information, a circuit to reproduce an RF signal is provided. At least a pair of photo sensors are arranged adjacently in a direction parallel with a tangential line of a recording track of an information recording disc. A light beam is irradiated onto the recording surface of the disc and the reflected light from the recording surface is received by these photo sensor. The phases of both output signals of the photo sensors are made coincident by the phase shift means. The resultant output signals having the same phase are added thereby to form the RF signal. For this purpose, the phase difference between both output signals of the photo sensors is detected and either one of phases of the output signals is shifted in accordance with the phase difference detecting output.

Abstract: A novel optical read and write information storage system is described which comprises a radiation source such as a laser for writing and illumination, the radiation source being capable of radiating a preselected first frequency; a storage medium including at least one layer of material for receiving radiation from the radiation source and capable of being surface modified in response to said radiation source when operated in a writing mode and capable of generating a pattern of radiation of the second harmonic of the preselected frequency when illuminated by the radiation source at the preselected frequency corresponding to the surface modifications on the storage medium; and a detector to receive the pattern of second harmonic frequency generated.

Abstract: An optical system for guiding a read beam and a magneto-optical storage which utilizes a single beam splitter inserted in the beam path of a linearly polarized light beam directed onto a storage disk for splitting the reflected beam into a deflected beam path and onto photo detectors. This optical arrangement includes a polarizer and an astigmatic imaging system. One of the two photo detectors is a four-quadrant detector and the other of the two detectors can be split into two regions with each of these detectors being positioned in one of the two sub-beams. Data signals derived from the intensity differences between the sub-beams and control signals for both a focusing control and for tracking control are derived from the detectors. Preferably, the photo detectors and the integrated circuits are part of an integrated circuit which also includes electrical circuits for the arrangements for obtaining the raw data, the tracking signal and the focusing signal.

Abstract: Light beam emitted from a laser light source is focused by an objective lens and applied in this state to an optical information recording medium. In the optical path between the laser light source and the objective lens is disposed a diffraction grating inclinedly with respect to the optical axis. This diffraction grating not only reflects the light beam emitted from the laser light source but also separates it into zero order as well as +1st order and -1st order diffracted light beams. Thus, this diffraction grating functions not only as a diffraction grating but also as a mirror. The thus-separated light beams are applied to an optical disc and the reflected light beams from the optical disc are converted to electric signals by means of a photo detector. The .+-.1st order diffracted light beams are used as track servo beams for following the track on the disc. The zero order diffracted light beam is used for reproducing information signals provided from the track on the disc.

Abstract: In an optical head, recording, reproducing and guide laser beams are emitted from semiconductor lasers, and the laser beams are optically mixed by a mixed. The mixed laser beams are converged onto a tracking guide of a recording surface by an objective lens and are reflected from the recording surface. The reflected laser beams are separated into the recording, reproducing and guide laser beams by the beam separator. The recording and guide laser beams are shielded in the beam separator, and only the reproducing laser beam is directed to photodetecting regions of information, tracking error and defocus detectors.

Abstract: An optical head for a laser memory disk in accordance with the present invention comprises: a substrate (1); a waveguide layer (3) formed over a main surface of the substrate; a semiconductor laser (4) for injecting laser beams into the waveguide layer, the semiconductor laser being set in a hollow (17) dug down at least into the waveguide layer; a focusing grating coupler (6) formed on the waveguide layer for focusing the injected laser beams on the memory disk and introducing beams reflected back from the disk into the waveguide; beam splitter means (5) formed on the waveguide layer between the semiconductor laser and the focusing grating coupler, for bisecting each of the reflected beams at a prescribed acute angle; and photodetector means (10) for converting the bisected beams into electrical signals, the photodetector means being provided along both the sides of the semiconductor laser and situated not nearer to the focusing grating coupler as compared with the semiconductor laser.

Abstract: There is disclosed a tracking error detecting apparatus for an optical head, which includes a semiconductor laser apparatus, a diffraction grating, a beam splitter, an objective lens and a photo-detector, in which a laser beam from the semiconductor laser apparatus is divided into a main beam and two side beams at both sides of the main beam by the diffraction grating, the three beams are introduced through the beam splitter and the objective lens to an optical recording medium, beams reflected on the optical recording medium are introduced through the objective lens to the beam splitter and reflected thereon, the reflected beams are made incident on the photo-detector and detected outputs of at least two beams of the three beams from the photo-detector are used to produce a tracking error signal corresponding to the tacking state of the main beam on the optical recording medium.

Abstract: An optical information recording and reproducing system comprises a light source for emitting a working beam from a front end thereof and a monitoring beam from a rear end thereof, an optical system control circuit, a loop gain adjusting circuit and a photo detector. The monitoring beam emitted from the rear end of the light source is detected by the photo detector, and the loop gain of the servo loop control circuit for the focusing and/or tracking is automatically adjusted by means of the loop gain adjusting circuit according to the detected signal so that a desired closed loop control of the working beam can be performed according to the operation modes and the light beam power variation.

Abstract: An optical head assembly for recording information on an optical disc or for taking out information already recorded, the optical head assembly including a semiconductor substrate and a dielectric light conducting layer formed on the substrate, the light conducting layer being internally formed with optical elements for converging laser beam from a laser beam source onto the optical disc and directing the reflected beam from the optical disc surface toward a photo detector. Output signal from the photo detector is used for reading information and also for allowing the optical head assembly to trace a track on the optical disc.

Abstract: Information stored in a medium as multiple machine readable record entries arranged in frames which are themselves arranged in one or more channels may be read by observing each frame in turn with a substantially known array of detector elements, each having a limited field of observation, producing a set of observed values for each frame. Modified values, indicative of the record entries of the frame, may be generated utilizing both the limitations on the range of the possible values of the record entries and predetermined manipulations of the observed values. As a result, any fractional misregistration between the record entries and the detector elements may be corrected. Position markers may be employed to determine where reading should occur. To distinguish local faults in the position markers, the markers may be observed in turn and values indicating marker position may be stored for a predetermined number of preceding markers.

Abstract: A photosensor device and an optical pickup device incorporating the photosensor device are advantageously used in an optical compact disc player of the type where the optical pickup device is driven along a path at an acute tilt angle relative to the sides of a rectangular casing. The photosensor has a plurality of photosensitive elements aligned in a first direction and a plurality of terminal leads extending parallel to each other and perpendicular to a second direction so that the photosensor may be mounted on a circuit board in a conventional configuration to save space. Within the optical pickup device, the photosensitive elements are aligned at a mounting angle which is a function of the tilt angle so that the three optical beams are received thereon in the proper orientation.

Abstract: An apparatus for reading a recorded medium using an extended cavity laser in which the recorded medium is an integral part of the laser cavity. Recorded mediums for producing a Kerr effect, differentially reflective mediums and mediums capable of undergoing stimulated emissions are disclosed.

Abstract: An optical head control signal generator comprising a lens (7) disposed in an optical path of a reading light beam caused by an optical head to be incident upon a recording medium and modulated by the recording medium, first, second, third and fourth photosensitive elements (D.sub.2a, D.sub.1a, D.sub.3a, D.sub.4a) divided as four quarters by perpendicular straight lines and responsive to the reading light beam for producing detected outputs based on an outer peripheral portion of a diffraction pattern formed on an exit pupil surface of the lens (7) by the reading light beam, and a synthesizing circuit (28) for producing a first sum output by adding the detected outputs from the first and third photosensitive elements (D.sub.2a, D.sub.3a) and a second sum output by adding the detected outputs from the second and fourth photosensitive elements (D.sub.1a, D.sub.

Abstract: An automatic focusing device for controlling the position of the objective lens relative to the information recording medium is provided with an astigmatic optical system which receives the reflected light beam reflected by the information recording medium. The light receiving surface of a light detector included in the astigmatic optical system consists of a central light receiving section formed approximatley symmetrically with respect to two axes intersecting each other perpendicularly and having a constricted central portion, and two side light receiving sections formed approximately symmetrically with respect to those two axes and opposite to each other. The light reception signal given by the central light receiving section and the light reception signals given by the side light receiving sections are fed to a focal position detecting circuit which gives a signal corresponding to the deviation of the objective lens from the focused position, on the basis of the light reception signals given thereto.

Abstract: Apparatus for reproducing motion picture photographic (optical) sound-tracks is disclosed in which significant information regarding track placement, slit illumination, azimuth and impulse noise is derived by dynamically processing and comparing the signals obtained by reading each half of a bilateral sound-track. In a further embodiment a pair of detector elements monitors the septum between two tracks in order to detect lateral film misalignment.

Abstract: A two-segment contact buried heterostructure (BH) laser is pumped by a current applied to its absorber contact from a source of high impedance on the order of 100K.OMEGA. or more. The parasitic resistance between the absorber contact and the gain contact is high on the order of 10K.OMEGA.. For a given absorber (bias) current the laser exhibits a relatively wide hysteresis on the order of 1 mA or more in the light vs. gain contact current. Such a laser is highly useful as a bistable optical element. The laser is also bistable with selected pump gain and absorber currents to exhibit a wide hysteresis of voltage across the absorber contact vs. relative amounts of light which is reflected back to the laser as feedback. The laser serve both as a light source and as a detector for reading out binary information stored as light reflective spots on a medium, e.g. a video disk.

Abstract: An optical memory device comprises a modulator for modulating a laser beam in accordance with recording data, an objective lens for focusing the output light beam from the modulator on a recording medium, a sensor arranged in the far field of the objective lens, and a judging circuit for detecting an erroneous writing operation in accordance with an output from the sensor and the recording data. The sensor has a square detecting surface divided into four segments by lines which form angles of .+-.45.degree. with respect to the direction of relative movement between the recording medium and the focused light beam. The difference between the sums of outputs from two pairs of opposing segments is supplied to the judging circuit.

Abstract: A focusing arrangement for an optical disk system that inhibits focus servo loop operation when the optical head objective lens is outside of a focus range distance with respect to the disk. In the optical head a laser beam converged by the objective lens is projected onto the light-reflecting layer of an optical disk. The laser beam reflected from the light-reflecting layer of the disk is projected to the light-receiving surface of a photodetector through the objective lens, a light shielding plate, a projection lens and a cylindrical lens. The laser beam is then projected to the light-receiving surface of the photodetector, thus forming a pattern thereon. As the objective lens moves along its optical axis, the laser beam is deviated and the pattern moves in a specific direction. The photodetector comprises first and second photosensitive regions.

Abstract: An optical system for recording information on or retrieving information from a rotating disc is disclosed herein. In this system a beam of light located on one side of the disc is directed onto and laterally across a given track of the disc. The track serves to contain the recorded information and, ignoring this information, is characterized by a predetermined light transmissivity curve in its cross-direction. An arrangement for maintaining the beam and given track in a fixed lateral position relative to one another as the disc rotates, even if the track moves laterally to a limited extent from its intended path of movement, is also disclosed herein.

Abstract: A stylus cartridge is equipped with a pair of integrally-molded flexural retaining fingers for locking a stylus arm within the confines of the cartridge body. When a slider member disposed on the cartridge is acted upon, it spreads the retaining fingers apart to release the stylus arm.

Abstract: Recovery from a record of data recorded in an information track, comprising depressed areas of a given width, a given depth, and variable length, alternating along the length of the track with relatively non-depressed areas, is effected by an optical playback system. The playback system employs means for focusing light from a laser source on the information track as a light spot having a diameter which is diffraction limited. The focusing system includes an independent light source (e.g., laser) which impinges on the surface of the record as a circular spot which illuminates a plurality of elongated tracks. The circular spot is imaged by a lens system on to a detector plane which is positioned at a plane which is conjugate to the record surface.

Abstract: Optical sound reproduction method and apparatus are provided for use with motion picture film having an optical dye sound track. The sound track preferentially modulates visible radiation while the silicon photoreceptor incorporated in the sound reproduction apparatus preferentially responds to infrared radiation. By positioning a suitable energy conversion device between the sound track and the photoreceptor, the modulated visible radiation--prior to striking the photoreceptor--is transduced into modulated radiation of longer wavelength nearer to the infrared portion of the spectrum. The signal provided by the photoreceptor is correspondingly enhanced since the impinging radiation has been shifted in wavelength toward the preferential response region of the photoreceptor. One suitable energy convertor is a fluorescing layer that absorbs visible radiation and emits radiation of longer wavelength in response thereto.

Abstract: An optical read unit is described for scanning a record carrier with a radiation-reflecting trackwise-arranged information structure. The read unit utilizes a diode laser which generates the read beam and also detects the information stored on the record carrier. The read unit is also provided with an opto-electronic system for detecting the position of the read spot relative to a track to be read and the position of the plane of focussing. The diode is mounted in a housing and the unit includes electromechanical apparatus for moving the housing in two perpendicular directions so as to correct the position of the read spot. The objective system for the formation of the read spot is of simple construction.

Abstract: Apparatus for scanning variable area optical sound tracks wherein a plurality of discrete photo sensors examine small fractional portions of the sound track width. Selection of the number of sensors in relation to photographic grain dimensions results in converting annoying quantizing noise to more tolerable random noise while using a practical number of sensors. Electronic processing of the sensors' outputs reduces impulse noise from dirt and scratches.

Abstract: Reflected light from the record in a optical disk player is directed at a string of photo sensitive diodes. Two adjacent diodes of this string of diodes receive light from a selected portion of the track on the disk. The outputs of these two adjacent diodes are summed together to generate the output signal for the optical disk player. The outputs of the two diodes are also subtracted from one another to generate a differential signal for tracking purposes. The magnitude of this differential signal is a measure of the relative magnitudes of the signals on the two adjacent diodes and therefore is one indication of how much of the light from the selected portion of the track reaches each of the diodes. When this differential output becomes larger than a preselected value, decode circuitry responds by changing the combination of adjacent diodes in the string to generate the video output signal and the difference signals.

Abstract: An optical scanner A for a video recording disc B includes a photo detector 6 for sensing the light from a laser source 1 reflected back from the disc. The low frequency and d.c. components of the photo detector output are compared with a reference voltage to derive an error signal. The latter, after compensation, amplification, and limiting, is applied to a regulator 23 to control the laser source discharge current, and thereby its intensity.

Abstract: System, method and record medium for the reproduction of pictures and related audio information on a television receiver or monitor. Video information for discrete frames of the picture is recorded in spaced apart tracks on the record medium, and extended audio information for each frame is recorded in a plurality of individually transcribable tracks between the video tracks. The information is read simultaneously from one of the video tracks and from all of the audio tracks for one frame, and the information from successive ones of the audio tracks is processed sequentially to provide extended sound during repeated reproduction of the picture.