Abstract: An optical head includes: a light source for emitting light; first optical element for forming at least three light beams from the light emitted from the light source; second optical element for converging said at least three beams on a storage medium; and a photodetector for receiving said at least three beams reflected by the storage medium to generate electrical outputs in accordance with an intensity of the light beams, the photodetector including; a semiconductor substrate; a light receiving section formed on a surface of the semiconductor substrate for receiving the light beams reflected by the storage medium; a plurality of input terminals for receiving a supply of a predetermined potential; and a plurality of output terminals for outputting electric signals, wherein the light receiving section includes a plurality of light receiving elements for signal detection provided apart from each other on the surface of the semiconductor substrate and a plurality of stray light carrier absorption regions provid

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: A multi-element grating beam splitter with a reflection grating for use in providing a front facet detector signal in an optical system. The multi-element grating beam splitter includes first, second, third, and fourth grating elements for separating a return beam reflected and diffracted from a data track on an optical storage medium into first, second, third and fourth portions, respectively. The grating beam splitter also includes a fifth grating element, which is preferably a reflection grating, for directing a portion of an incident radiation beam onto a front facet detector. The front facet detector signal may be subtracted from a data signal resulting from detection of the first, second, third and fourth portions of the return beam in order to limit the effect of optical source noise on the data signal.

Abstract: A light source for generating light beams, a diffraction grating for splitting the light beam emitted from the light source into at least three light beams, and an objective lens for receiving the reflecting light beams from the recording medium, the magnification of the objective lens being -6.0 to -12.0, make up a collimatorless optical system. The reflecting light beams emanating from the objective lens are split by a beam splitter, these split light beams are each split into at least three light beams by a Wollaston prism, and are incident on a photo detecting element. A tracking error signal, a focusing error signal, and a magneto-optical signal are generated using the light beams received by the photo detecting element. The beam splitter and the Wollaston prism may be substituted by a multifunctional Wollaston prism. If the nine split light beams are all received by the photo detecting element, the signals produced by the photo detecting element are large in amplitude.

Abstract: In a combined optical and magneto-optical recorder, data stored in pits and a magnetic layer may be simultaneously detected with an optical scanning device. Reflected light is divided by a polarizer and directed to one of two photodetectors depending on the polarization of the reflected light. A magneto-optic recorded data signal (containing cross-talk) is detected by differencing the signals provided by the two photodetectors. Reflected light is also directed through a .lambda./4 polarizer and a second beam divider to third and fourth photodetectors depending upon the polarization of the light passing the .lambda./4 polarizer. A second difference signal, which essentially conforms to the cross-talk, is generated from the differences of signals provided by the third and fourth photodetectors. The two difference signals are combined to produce a cross-talk free magneto-optic recorded data signal.

Abstract: In an optical pick-up device adapted for detecting light reflected from a disc by using a photo detector to drive an object lens in focus and tracking directions on the basis of a detected signal of the photo detector, a multi-lens for improving sensitivity and accuracy of the photo detector and a multi-lens holder for holding the multi-lens are provided, wherein the multi-lens holder is such a shape that it traverses a first optical path from a light source to a beam and traverses a second optical path from the beam splitter to the photo detector. Thus, adjustment of the spacing between the multi-lens and the photo detector can be facilitated, and the shape of the optical pick-up device itself can be thin and light-weight.

Abstract: An optical pickup head apparatus comprising: a light source; an imaging optics for receiving a linearly polarized light beam emitted from the light source, and converges it on a small spot on an information medium; photodetector units for receiving the light beam being reflected and diffracted at the information medium and output electric signals corresponding to received light quantities; a liquid crystal hologram consisting of a pair of transparent substrates, a liquid crystal sandwiched therebetween through a pair of transparent electrodes, either of the transparent electrodes being formed with a hologram pattern; and a Faraday rotator for rotating a polarized direction of light beam by 45 degrees in a light path leading from the light source to the information medium and, further, rotates the polarized direction of the light beam by 45 degrees in its opposite light path.

Abstract: An apparatus and method for reducing optical source noise and other common-mode system noise in a data signal read from an optical storage medium. An exemplary apparatus in accordance with one aspect of the present invention includes a first detector to generate the data signal by detecting a return beam resulting from application of a radiation beam to the medium; a second detector to generate a source monitor signal by detecting radiation from an optical source providing the radiation beam; a correction circuit adapted to receive the data signal and the source monitor signal and generate a corrected data signal therefrom; and means for controlling the gain of a signal path of at least one of the data signal and the source monitor signal in response to, for example, low-frequency amplitude differences between the data signal and the source monitor signal. One or more delay lines may be included to provide phase matching of the data signal and source monitor signal at the correction circuit input.

Abstract: An optical head is used in a magnetic field modulation type magnetooptical recording/reproducing apparatus. The optical head includes a device for irradiating a magnetooptical record medium with a light beam, a separating device for separating a reflected light beam from the magnetooptical record medium into two beams to be projected onto a single plane, a single photodetector provided with two two-divided light receiving portions for respectively receiving the two beams, and a single convex lens element for forming images of the two beams as light spots on the single photodetector.

Abstract: An optical pickup apparatus having a photo-detection unit having a plurality of detectors, a unit for converting a light beam emitted from a recording medium on which information is magnetically recorded and intensity-modulated, and splitting the light beam into two beams guide them respectively onto different areas of the photo-detection unit, and a device for processing outputs from each area of the photo-detection unit to provide an information signal.

Abstract: An information recording system including a photoelectric sensor being semiconductive and having a photoconductive layer stacked on an electrode, and an information recording medium having an information recording layer stacked on an electrode so that information can be recorded on the information recording layer by an electric field or electric charge. The photoelectric sensor and the information recording medium are disposed to face each other, and information exposure is carried out with a voltage being applied between the two electrodes, thereby enabling information to be recorded on the information recording medium. The photoconductive layer of the photoelectric sensor is capable of amplifying an electric field or electric charge given to the information recording medium, so that the intensity of electric field or the amount of electric charge given to the information recording medium can be increased to a level higher than the light energy actually applied.

Abstract: An objective lens causes light emitted from the light source to converged onto an optical recording medium. A beam splitter separates light, reflected from the optical recording medium, from the bundle of rays emitted from the light source. A detective lens causes the light separated by means of the beam splitter to be converged. A detective photosensitive element is disposed at a position at which the light converged by means of the detective lens approximately converges. The detective lens has a first and second surfaces. The first surface faces the beam splitter and is formed to be convex so as to cause the bundle of rays to converge. The second surface comprises two surfaces which are combined with one another so that the line of intersection, formed where the two surfaces meet, does not intersect the axis associated with the convexity of the first surface.

Abstract: An optical recording/reproducing head device which includes a diffraction grating for splitting a light beam radiated from a light source into at least three light beams, an objective lens for converging the three light beams on a signal recording surface of a disc-shaped optical recording medium, driving means for driving the objective lens along a direction parallel to its optical axis and within a plane perpendicular to the optical axis, a beam splitter for splitting the light beam incident via the objective lens, a first photodetector having a light-receiving surface divided by two boundary lines into four sections, second and third photodetectors arrayed in a direction parallel to one of the boundary lines on both sides of the first photodetector and fourth and fifth photodetectors arrayed in a direction perpendicular to the one of the boundary lines on both sides of the first photodetector, a splitting optical element arranged between the photodetectors and the beam splitter for splitting each of the th

Abstract: A system and method for recording data on an optical recording medium. One system in accordance with the invention includes an optical source to generate a radiation beam at a first wavelength; and an optical recording medium to which the radiation beam is applied, wherein the medium has an absorption response with an absorption edge between a second and third wavelength, and the first wavelength is between the second and third wavelength, such that an amount of radiation absorbed by the medium varies as a function of wavelength for wavelengths near the first wavelength. The radiation beam induces a shift in the absorption response in a region of the medium illuminated by the beam such that the medium absorbs additional radiation at the first wavelength and the quality of a mark formed on the medium by the beam is thereby improved.

Abstract: An optical information detection circuit having first and second photodiodes (referred to as "PD") and two resistances so that a power voltage Vcc is divided by the two resistances. A potential difference between the power voltage Vcc and the connection point between the two resistances is applied as a reverse bias to the first PD, and the potential at the connection point is applied as a reverse bias to the second PD. The photomagnetic signals respectively input to the first and second PD systems of a differential optical detection system have an opposite phase relation therebetween. The first PD and second PD obtain signals from a cathode and an anode, respectively. The currents from the first PD and second PD thus have an in-phase relation, are converted into voltages by the two resistances and summed, as well as being output as a photomagnetic signal from an output terminal at the connection point.

Abstract: An optical recording disk system, which has a light-activated silicon controlled rectifier (LASCR), a resistor, and a recording film in each pixel, is used to record the optical information form the write beam. The write beam triggers the LASCR, which behaves as an optical switch, and lets an electric current pass the LASCR to generate either a thermal effect or an electro-optical effect on the recording film.

Abstract: An electronic device comprising a diamond illuminated with ultraviolet radiation, a light source for illuminating the diamond with visible light, and a means for measuring a photocurrent induced in the diamond. The ultraviolet radiation has wavelengths shorter than about 230 nm corresponding to the energy bandgap of the diamond and is made to impinge on the diamond. Then, the light which has wavelengths longer than about 230 nm is made to impinge on the diamond. The photocurrent induced in the diamond is measured. In this way, the amount of the previously emitted ultraviolet radiation having wavelengths shorter than about 230 nm is known. Although the diamond is a primary substance to be illuminated, the substance to be illuminated comprises a material selected from a group consisting of diamond, boron nitride, aluminum nitride and a multi-layer thereof.

Abstract: An apparatus which includes a recording or reproducing unit for recording or reproducing data on or from a disc, a data transmission/reception unit for transmitting playback data reproduced by the recording and reproducing unit from the disc to an external computer and receiving recording data supplied from the computer for supplying the received recording data to the recording and reproducing unit, a system controller for receiving a command supplied from the computer for controlling the data receiving unit, a temperature sensor for detecting the temperature within a main body of the disc recording and reproducing apparatus, and a recording/playback controller for controlling the operation of the recording and reproducing unit responsive to the command supplied from the computer via the system controller and a detection output of the temperature sensor.

Abstract: A focus error detecting device includes a reflected beam splitter and at least two two-division photodetectors. The reflected beam splitter includes a diffraction grating part and a non-diffraction grating part separated by a line dividing a reflected beam. The dividing line projects to a line orthogonal to a guide groove on the information recording medium. The diffraction grating part produces a first split beam, and non-diffraction grating part produces a second split beam. Each two-division photodetector receives one of the first and second split beams incident and their light receiving sections, and produces a signal for effecting focus control.

Abstract: A head position controlling device in which the head position may be controlled accurately even with a magneto-optical disc having regions with different reflectance values. A gap sensor consisting of a light emitting element 5 and light receiving elements 6 and 7 are arrayed along the track direction of a magneto-optical disc to prevent unequilibrium in the volume of received light at the light receiving elements 6 and 7.

Abstract: An optical recording medium includes a substrate, first information for modulating a phase of read light radiated on the substrate, and second information for modulating an amplitude of the read light radiated on the substrate. The first information and the second information are arranged in parallel to each other on the substrate in a predetermined arrangement direction. A method and apparatus for performing reproduction using this medium are also disclosed.

Abstract: An optical information recording/reproducing device is constituted of a focus control circuit connected to a controller, a tracking control circuit, a data processing circuit, and a card feed control circuit. The data processing circuit includes a plurality of I/V converters for converting signals received by a plurality of signal reproducing light receiving elements arranged to an optical detector into current/voltage, and a plurality of binary circuits each for converting the output from the I/V converters into a binary signal in a reference level. The data processing circuit includes a selector for selecting at least two outputs of a plurality of binary circuits. The data processing circuit includes a plurality of bit-clock producing circuits and a plurality of demodulation circuits. The bit-clock producing circuits produce bit clocks based on binary signals originated from selectors and a plurality of binary circuits which are not connected to the selectors.

Abstract: An optical disc has recorded information and is irradiated with a laser beam at a first spot for reading information recorded on the disc and at a second spot. The second spot has such an area that intensity of light reflected at the second spot does not change with change of the recorded information. A first photodetector is provided for detecting intensity of light reflected on the first spot, and a second photodetector is provided for detecting intensity of light reflected on the second spot. A subtracter is provided for producing the difference between outputs of the first photodetector and the second photodetector and an alternating current detector is provided for producing an output at a slice level where the difference of the subtracter becomes zero.

Abstract: In response to a test signal received at a test terminal, one terminal of a first computation circuit and three terminals of a second computation circuit are each provided with a reference voltage, or a ground potential, which is available at reference voltage supply terminals associated with photo detectors. Another terminal of the first computation circuit and the second computation circuit are each provided with a detected voltage. If the functions of the computation circuits are not defective, function signals will be obtained each having a value which corresponds to an imbalance between the detected voltage and the reference voltage. Thus, only one test terminal is required, which reduces the size of the semiconductor integrated circuit.

Abstract: In a guide pattern detecting circuit installed in a tracking control circuit, a sum of outputs of guide pattern light receiving elements, .SIGMA.En, is converted from a current into a voltage by an I-V converter. The sums of outputs of odd-numbered light receiving elements for clock signal production and of even-numbered light receiving elements for clock signal production, .SIGMA.B2n-1 and .SIGMA.B2n, are converted from currents into voltages by I-V converters 31b and 31c. The sums of outputs converted from currents into voltages, En, and B2n-1 and B2n are supplied to two differential amplifiers. One of the amplifiers outputs (.SIGMA.En-.SIGMA.B2n-1), and the other one thereof outputs (.SIGMA.En-.SIGMA.B2n). The differential outputs (.SIGMA.En-.SIGMA.B2n-1) and (.SIGMA.En-.SIGMA.B2n) are supplied to two low filters, whereby dc components are cut off. These differential signals are supplied to two multipliers and then squared.

Abstract: A plurality of tracks are spirally arranged in a group on an optical disc. The tracks in the group are simultaneously radiated by laser beams. Adjacent tracks in the group are disposed at a radial distance d1, and adjacent spots of the laser beams on the tracks are disposed at a radial distance ds which is smaller than the distance d1.

Abstract: An optical disk includes a recording medium having a disk shape, and a plurality of signal pit strings formed on the recording medium and arranged in a circumferential direction of the optical disk. Each of the signal pit strings includes a plurality of signal pits arranged in a line in a radial direction of the optical disk. An optical pickup apparatus includes a photodetector having a plurality of photoelectric elements. A light spot is sequentially projected onto the signal pit strings, and a reflected light therefrom is converged by an objective lens. An image formed by the objective lens is detected by the photodetector located in an image forming position of the objective lens. The unit information pieces contained in one of the signal pit strings are simultaneously read by the photoelectric elements. In this manner, the signal pit strings are sequentially read while the optical disk is being rotated.

Abstract: A system for reducing crosstalk in an optical scanning device for recording and reading optical data and magneto-optical data arranged in tracks of a recording medium includes a source for providing two light beams which are scanned along the tracks. The light beams are polarized in two polarization directions, are focused onto one of the tracks and are separated by a predetermined distance along the direction of the tracks, when incident on the tracks. Reflected light from the recording medium is focused onto first and second pairs of sensors. The difference of the signals from the first pair of sensors is compared with a delayed version of the difference of the signals from the second pair of sensors to provide a further signal representing magneto-optically recorded data. Signals from a first sensor of each pair of sensors may be summed to detect optically recorded data.

Abstract: In an optical information storage an retrieval system, the tracking and focus signals have, in the past, been generated by directing radiation beams from each section of a dual half aperture prism to spatially separated dual element sensors and processing the signals from the pair of dual element sensors. In order to reduce cross-talk between the focusing and tracking signals, a radiation beam which has interacted with the optical storage medium is divided into two portions. The first portion of the radiation beam is directed to a dual prism and the radiation beam from each portion of the prism is applied to a different dual sensor. However, the dual half aperture prism divides the radiation beam which has interacted with the storage medium along a plane perpendicular to the projection of the optical storage medium track being monitored. The focusing signal is derived from this pair of dual element sensors.

Abstract: An apparatus reads data signal recorded on an optical disc on which a gathering track including n recording tracks and a guard track neighboring to the gathering track are spirally formed. The apparatus includes: light beam irradiating unit for irradiating (n+1) light beams onto boundaries of the n recording tracks and the guard track, photodetecting unit for receiving (n+1) light beams reflected by the surface of the optical disc and producing (n+1) track boundary data signals, and computing unit for calculating the (n+1) track boundary data signals to produce n read-out data signals corresponding to the data signals recorded on the n recording tracks.

Abstract: The present invention relates to a photo-detecting device which records/reproduces a signal such as visual information on/from an information recording device such as an optical disk, and more particularly to a structure of a photo detector that receives light reflected from the optical disk, and a method for processing the signal outputted therefrom, and it is an objective of the present invention to obtain a reproduced signal having a good SN ratio without any effect of other signals by a rather simple structure.

Abstract: An optical data storage system comprises a laser for generating a beam of light, an optical data storage media, transmission optics for directing the beam of light to the optical medium, reception optics for receiving a reflected beam from the medium, and circuits for generating a data, tracking error and focus error signals. The reception optics includes a segmented detector. The signals from at least two of these segments are differentially adjusted such that the resulting output focus error signal is approximately independent of nonfocus wavefront aberrations.

Abstract: A concurrent recording and reproducing optical disc has a magneto-optical medium film coated on a ROM disc having rows of pits. The magneto-optical film is arranged by a predetermined interval between the two adjacent rows of the pit rows. The predetermined interval is determined by a dark Airy disc circle band of a beam spot obtained by focusing a light beam on the concurrent recording and reproducing optical disc. Preferably, two light beams are focused on the optical disc to provide first and second beam spots. The first beam spot is focused on one of the pit rows, and the second beam spot is focused on an area between two selected pit rows.

Abstract: An optical disk has: a substrate of disk shape; a recording medium formed on the substrate, and having a recording surface on which a plurality of tracks are formed; and information pits formed on the tracks. Each of the information pits has a first pit portion having a first level from the recording surface and a second pit portion having a second level lower than the first level. A pit direction angle indicating an angle between a direction connecting the first pit portion and the second pit portion to each other and a circular direction of the optical disk, is equal to one of predetermined equiangular angles around the center of the information pit. The pit direction angle corresponding to recorded information pieces read by projecting a laser beam onto the recording medium.

Abstract: An optical pickup apparatus reproduces signals recorded on an optical disk, which has a signal track in which a plurality of signal pit strings are arranged in a circumferential direction of the optical disk, each of the signal pit strings including a plurality of signal pits arranged in a line in a radial direction of the optical disk, the optical disk being rotated at a speed v relative to the optical pickup apparatus.

Abstract: In a sensor system for use in the read/write head of an optical information storage and retrieval system, a dual prism separates the resulting radiation beam into two radiation components, the radiation components having a division perpendicular to a projection of a data track or groove on the storage medium projected on the dual prism. Each of the two radiation components is focused by a focus sensor lens on one of two four-quadrant sensors, the four-quadrant sensors forming the system sensor array. The application of the two radiation components generates a tracking signal, a focusing error signal, and a data signal. The orientation of the dual prism results in reduced cross-talk between the tracking signal, which is derived from positive and negative diffraction components, and the focusing signal, which is derived from radiation components having contributions from both the positive and negative diffraction components.

Abstract: In the optical recording element of the invention, alignments of long thin pits inclined in various directions with respect to the track direction are formed on the tracks and information is recorded therein according to the different inclines of the pits, thereby performing higher-density and larger-volume recording without reducing the spacing between each pit and the track pitch. The invention also discloses an optical data retrieval system for use with the above optical recording element, which scans the pit alignments with a laser beam spot, detects the inclines of the pits by obtaining the distribution of the intensity of reflected light which is caused by light diffraction at the pits, and plays back information in accordance with the inclines. Therefore, not only can the substantially same structure as that of a standard type optical data retrieval system be applied to the invention without making any complicated change, but also cross-talk is less likely to be produced in the read out signals.

Abstract: The beam of light reflected from an optico-magnetic recorded medium is reflected by an optical pick-up onto one optical or another in accordance with the direction that the beam's plane of polarization is rotated in. A data signal is obtained from the difference in the photovoltages of the two photodetectors.

Abstract: A rotating magnetic head for a magnetic recording reproduction system. The rotating magnetic head detects the position of the rotating head placed on the periphery of a rotating drum, and perform servo control of the position of the movable head. The detection of the position of the rotating head is realized by an optical, non-contact mechanism or by detecting the difference of the track scanned by fixed heads. The former requires more than one movable heads and the latter requires a fixed head.

Abstract: A signal processing circuit for a disk apparatus with an optical head, which causes photodiodes to detect light acquired by irradiating light from a laser diode on a disk that has an address portion and data portion recorded thereon, and performs photoelectric conversion of the light. A level converter alters the level of the signal detected by each photodiode and provides an output signal. A detector detects a level of the output signal by switching time constants between the address portion and data portion. Using a bias corresponding to the detected level, the levels of signals detected by the photodiodes are changed.

Abstract: An apparatus for optically reading information out of an opto-magnetic disk including a semiconductor laser emitting a polarized laser light beam which is made incident upon the opto-magnetic disk via beam splitter, reflection surface and objective lens. The light beam reflected by the opto-magnetic disk is made incident upon a photodetector by the objective lens and beam splitter. In order to compensate for the phase difference of P polarized and S polarized light components of the light beam reflected by the opto-magnetic disk within a wavelength over which the wavelength of the light beam might fluctuate due to the temperature variation, multi film constructions are provided in the beam splitter and reflection surface, the multi film constructions having such characteristics that the wavelength dependencies of the phase difference of the beam splitter and reflection surface can be made substantially a constant value such as zero and 90 degrees.

Abstract: An optical information recording/reproducing apparatus provided with a device for irradiating an information track of an optical information recording medium with a preheating light beam. Simultaneously, a recording/reproducing light beam irradiates a light spot of the preheating light beam on the recording medium. The light intensity of the preheating light beam is varied in accordance with the environmental temperature of the apparatus detected by a detector. By such a construction, the recording/reproducing condition of information is kept constant, irrespective of the environmental temperature.

Abstract: An apparatus for controlling an emission power of a laser diode is used in an apparatus for recording and reproducing information of an optical disk, which has a power calibration area and to which a disk discrimination code is recorded.

Abstract: An optical head comprises a grating lens for diffracting light beam separated from the light beam path. The grating lens is composed of a plurality of regions having different focal length and diffraction direction so that the light beam is divided into a predetermined number of light beams. Therefore, a conventional beam splitter or polarizing beam splitter is replaced by a grating lens so that the optical head can be smaller and lighter, and the precision of detecting a track and focus errors is improved.

Abstract: An apparatus for reading variable area optically encoded soundtracks has a light source, a lens system and a detector. The detector can be a linear array, for example a CCD array, with an integral slit, with the lens system imaging the soundtrack in the plane of the slit. The apparatus includes circuitry for processing the detector output signal. The processing circuitry can be provided with a feedback control circuit to condition the detector output signal so that the resulting audio signal is not affected by variations in the film or electronic components. Further, a circuit can be included for detecting whether an analogue or digital soundtrack is present, and automatically switching the output of an amplification circuit between analogue and digital outputs.

Abstract: In the optical recording element of the invention, alignments of long thin pits inclined in various directions with respect to the track direction are formed on the tracks and information is recorded therein according to the different inclines of the pits, thereby performing higher-density and larger-volume recording without reducing the spacing between each pit and the track pitch. The invention also discloses an optical data retrieval system for use with the above optical recording element, which scans the pit alignments with a laser beam spot, detects the inclines of the pits by obtaining the distribution of the intensity of reflected light which is caused by light diffraction at the pits, and plays back information in accordance with the inclines. Therefore, not only can the substantially same structure as that of a standard type optical data retrieval system be applied to the invention without making any complicated change, but also cross-talk is less likely to be produced in the read out signals.

Abstract: An optical head, for an optical disk recording/reproducing apparatus, for irradiating a recording medium by a light beam emitted from a light source and introducing an information light formed by a light beam reflected from the recording medium to a photo detector, a shift of an optical axis of the information light being minimized. The optical head includes a unit for receiving the information light which is reflected from the recording medium, a first reflecting unit for reflecting such information light, a second reflecting unit for reflecting the information light reflected by the first reflecting unit and for directing the reflected information light toward the photo detecting system, and a unit for emerging the information light reflected by the second reflecting unit to the photo detecting system.

Abstract: To prevent a drop in signal level at high spatial frequencies, an optical information reproducing apparatus retrieves the primary output of light reflected from the surface of a recording medium. In the different embodiments of the invention, either a shield plate with a pinhole in the path of the light is provided, or a photodetector having a plurality of light-receiving elements is provided, a selection circuit being connected to the elements and selecting the highest output thereof.

Abstract: A method and apparatus for reducing the number of errors generated when reading digital data stored on a recording medium such as film, the method comprising passing light of two different frequencies (i.e., two different frequency bands) through the film, one frequency being modulated by digital data stored on the film and the other being unaffected by the stored data. The light that is unaffected by the stored data is modulated by debris on the film such as dirt and is used to flag data bits that may be in error to thereby facilitate an error correction process. In the first disclosed embodiment the two frequencies of light are processed separately to obtain the digital data and error flags. A second embodiment combines all light passing through the film to produce digital information that includes error flags.

Abstract: An optical pickup apparatus is disclosed which comprises an optical detector formed on a substrate for detecting light reflected by a recording medium, a pattern formed on the substrate, a first block on which the substrate is fixed, a first reference surface formed on the first block substantially in parallel with an optical axis of the light to be detected, a second block arranged to be movable so as to be adjusted in a plane perpendicular to the optical axis and to support the first block, a second reference surface formed on the second block so as to correspondingly contact with the first reference surface; and a relay substrate fixed on the second block and electrically connected to the pattern.