Abstract: In one aspect, the present disclosure related to a method for modifying a beacon light source for use in a light-based positioning system. In some embodiments, the method includes selecting a modulation scheme for the light source, determining a duty cycle for the light source based on the modulation scheme, the duty cycle having a proportion of time the light source is in an on state and a corresponding proportion of time the light source is in an off state, the proportion of time the light source is in an off state resulting in reduced luminosity of the light source, and supplying additional power to the light source to compensate for the reduced luminosity of the light source by the duty cycle.

Abstract: In one aspect, the present disclosure related to a method for modifying a beacon light source for use in a light-based positioning system. In some embodiments, the method includes selecting a modulation scheme for the light source, determining a duty cycle for the light source based on the modulation scheme, the duty cycle having a proportion of time the light source is in an on state and a corresponding proportion of time the light source is in an off state, the proportion of time the light source is in an off state resulting in reduced luminosity of the light source, and supplying additional power to the light source to compensate for the reduced luminosity of the light source by the duty cycle.

Abstract: To provide a protection barrier, which includes an inlet from which laser light emitted from a laser device enters; an outlet from which the laser light is output towards an irradiation target; and a unit configured to prevent a leakage, where the unit is configured to reduce an intensity of the laser light leaked from the protection barrier, wherein the protection barrier is configured to surround a light path of the laser light emitted from the laser device.

Abstract: In one aspect, the present disclosure related to a method for modifying a beacon light source for use in a light-based positioning system. In some embodiments, the method includes selecting a modulation scheme for the light source, determining a duty cycle for the light source based on the modulation scheme, the duty cycle having a proportion of time the light source is in an on state and a corresponding proportion of time the light source is in an off state, the proportion of time the light source is in an off state resulting in reduced luminosity of the light source, and supplying additional power to the light source to compensate for the reduced luminosity of the light source by the duty cycle.

Abstract: A method of separating a mixture of acoustic signals from a plurality of sources comprises: providing pressure signals indicative of time-varying acoustic pressure in the mixture; defining a series of time windows; and for each time window: a) providing from the pressure signals a series of sample values of measured directional pressure gradient; b) identifying different frequency components of the pressure signals c) for each frequency component defining an associated direction; and d) from the frequency components and their associated directions generating a separated signal for one of the sources.

Abstract: In the optical information reproduction apparatus using Homodyne phase diversity detection, the S/N ratio of a reproduced signal is deteriorated due to the influence of a quantization noise generated in an A/D converter for digitalizing a differential signal. The optical information reproduction apparatus is arranged to have the A/D converter for digitalizing the differential signal having a vertical resolution equal to or higher than 9 bits.

Abstract: In the optical information reproduction apparatus using Homodyne phase diversity detection, the S/N ratio of a reproduced signal is deteriorated due to the influence of a quantization noise generated in an A/D converter for digitalizing a differential signal. The optical information reproduction apparatus is arranged to have the A/D converter for digitalizing the differential signal having a vertical resolution equal to or higher than 9 bits.

Abstract: The invention relates to the recording of soundtracks onto analogue cinema film, in particular the recording of digital created and/or digital/electronically stored representations of soundtracks onto film. The method according to the invention for comprises converting sound data from the digital soundtracks to sound image data, modulating light based on the sound image data, and imaging the modulated light onto a photosensitive film. The device according to the invention comprises at least one light source, processing electronics for converting sound data from the digital soundtracks to sound image data, at least one full frame device connected to the processing electronics, adapted for modulating light from the light source according to the sound image data, imaging optics for imaging the modulated light onto a photosensitive film.

Abstract: Circuits, architectures, systems, methods, software, and algorithms for detecting a modulation transition (e.g., a change from a written portion containing RF-modulated data to an unwritten portion containing only a wobble signal modulation) on an optical storage medium. The method generally includes steps of focusing a first spot of light onto an optical storage medium, wherein the first spot is substantially centered on a first track of the optical storage medium, focusing a satellite spot of light onto an optical storage medium, wherein the satellite spot at least partially overlaps a track adjacent to the first track, generating a satellite signal from light reflected from the optical storage medium from the satellite spot, and detecting the modulation transition by detecting a change in a level of the satellite signal.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. As an example, a pattern detection circuit is discussed that includes a distance calculation circuit and a comparator circuit. The distance calculation circuit is operable to calculate a noise whitened distance between a reference signal and a received input to yield a comparison value. The comparator circuit is operable to compare the comparison value with a threshold value.

Abstract: An optical disk apparatus is provided which can: prevent an SNR deterioration attributable to an increase in read speed; overcome difficulty in separating a read signal and HF signal components; reduce laser noise; and maintain high reliability even during a high-speed read operation. An optical disk is irradiated with laser light pulsed by a high-frequency signal generated by a HF oscillator. The output of an optical detector which receives laser light reflected from the optical disk is converted into an electric pulse read signal using a current amplifier. The pulse read signal is converted into a temporally continuous read signal using a combination of an AD converter and a DA converter.

Abstract: A hologram recording/reconstructing apparatus includes a spatial modulator in which a reference beam region and a reconstruction beam region are formed, and a controller configured to control a range of the reference beam region and a range of the reconstruction beam region. According to a temperature of a hologram recording medium during recording, the controller sets the range of the reference beam region to a first predetermined range and thereby sets a range of an incident angle of a reference beam on the hologram recording medium to a first predetermined angle range. According to a temperature of the hologram recording medium during reconstruction of recorded data, the controller sets the range of the reconstruction beam region to a second predetermined range and thereby sets a range of an incident angle of a reconstruction beam on the hologram recording medium to a second predetermined angle range.

Abstract: Digitally sampled real or sampled and down-converted complex data representing an RF signal are received. One or more statistical computations are calculated for each group of N data values. The one or more statistical computations are calculated for groups of N data values until a particular number of data values (K) are acquired. The one or more statistical computations calculated for each group are computed and stored at the time of acquisition and are available for immediate viewing on a display.

Abstract: Semiconductor nanocrystals surface-coordinated with a compound containing a photosensitive functional group, a photosensitive composition comprising semiconductor nanocrystals, and a method for forming semiconductor nanocrystal pattern by producing a film using the photosensitive semiconductor nanocrystals or the photosensitive composition, exposing the film to light and developing the exposed film, are provided. The semiconductor nanocrystal pattern exhibits luminescence characteristics comparable to the semiconductor nanocrystals before patterning and can be usefully applied to organic-inorganic hybrid electroluminescent devices.

Abstract: An optical pick-up and a disc apparatus having the same to overcome an inferiority of a tracking signal caused by an adjacent layer during the recording and/or reproducing of an optical disc with multiple recording layers, the optical pick-up including: a light source to emit light with a wavelength corresponding to a type of the optical disc; a light collecting unit to focus the light emitted from the light source to form a light spot on a signal recording layer of an optical disc having a plurality of recording layers; a photodetector to receive a signal light reflected by the signal recording layer and a noise light reflected by an adjacent recording layer different from the signal recording layer, and to detect a signal from the signal light; and an optical member to change an optical transmission of the noise light according to an incident angle of the noise light so as to decrease an intensity of the noise light entering the photodetector.

Abstract: Audio information stored in the undulations of grooves in a medium such as a phonograph record may be reconstructed, with little or no contact, by measuring the groove shape using precision metrology methods coupled with digital image processing and numerical analysis. The effects of damage, wear, and contamination may be compensated, in many cases, through image processing and analysis methods. The speed and data handling capacity of available computing hardware make this approach practical. Two examples used a general purpose optical metrology system to study a 50 year old 78 r.p.m. phonograph record and a commercial confocal scanning probe to study a 1920's celluloid Edison cylinder. Comparisons are presented with stylus playback of the samples and with a digitally re-mastered version of an original magnetic recording. There is also a more extensive implementation of this approach, with dedicated hardware and software.

Abstract: Techniques are provided for placing atoms inside an appropriate nanocavity for enhancing two-photon absorption and quantum information processing based on the Zeno effect. Techniques for fabricating suitable nanocavities include: 1) a short length of optical fiber polished on the ends with the ends coated to form suitable mirrors; 2) a continuous length of fiber with the equivalent of mirrors being formed within the fiber using Bragg gratings; 3) a single filament of glass (such as fused silica) being suspended between two mirrors (without any cladding) and surrounded by an atomic vapor, solid, or liquid; 4) a small glass sphere (such as fused silica) that has been melted on the end of an optical fiber; and 5) a small toroid (ring) of glass bent in a circle surrounded by suitable atoms.

Abstract: An optical reproducing apparatus in which reproduction of information is carried out by using an optical record carrier. In order to compensate a radial tilt between the surface of the record carrier and the objective lens, the objective lens is tilted. In the optical apparatus of the invention, the actuator of the radial displacement of the objective lens is used to also tilt the objective lens at the same time. A displacement of the objective lens in the radial direction by the actuator has a direct effect of tilting the objective lens. This is accomplished by a mechanical link between the radial displacement and the radial tilting. This has the advantage that there is no need for an extra tilt actuator to tilt the objective lens.

Abstract: A method for reconstruction the original groove configuration of a phonograph record. The methodology comprises providing an instrument for making measurements of the geometry of a groove of a phonograph record with the instrument in communication with a computer and the computer executing a reconstructive analysis code thereby reconstruct the groove geometry of the phonograph record using data obtained from the measurements of the geometry of the groove.

Abstract: An optical data storage system utilizes optical fibers for transfer of information to and from storage media. The storage media comprises magneto-optical storage disks. The optical fibers are low-birefringence optical fibers. As compared with conventional approaches, a polarization state conveyed by the optical fiber is accurately reproduced with reduced noise. Various noise reduction techniques are provided by substantially decreasing or eliminating spurious reflections (or the effects thereof) at end faces and of an optical fiber. In particular, various techniques, such as index matching, a cover slip method, laser modulation, or angle polishing, may be used to eliminate spurious reflections (or the effects thereof) at the front end face of the optical fiber. Various techniques, such as angle cleaving, index matching, or multi-mode fiber splicing, may be used to eliminate spurious reflections (or the effects thereof) at the back end face of the optical fiber.

Abstract: To provide a method of pseudogrounding which is capable of protecting against EMI by pseudogrounding communication lines, etc. without necessity of expensive ferrite cores and increasing the number of steps and cost. A wiring which is connected to an LSI (43) on a package and is connected to an external wiring (47) via a connector (461), radio-frequency connected via a capacitance (451, 452) to ta housing (42) in which protection against EMI is achieved so that the radiated noise energy is not higher than EMI restricted value level. This enables said wiring to be pseudogrounded.

Abstract: Optical waveguides exhibiting non-linear and/or electro-optic properties comprise a rare earth doped barium titanate thin film as an optical working medium. The thin film is metalorganic chemical vapor deposited on a substrate in a reactor to incorporate rare earth atoms in-situ in the barium titanate or other ferroelectric oxide host material.

Abstract: An optical disk recording device for conducting reading and recording of data through irradiation of laser beam on an optical disk medium comprises a photo detection circuit for receiving input of reflected light from an optical disk medium to detect a reproduced signal, a pre-amplifier for amplifying a reproduced signal from the photo detection circuit and outputting the amplified reproduced signal for monitoring, and a level shift circuit for shifting a level of a reproduced signal from the photo detection circuit increased with an increase of the amount of light in data recording operation to a preset value and outputting the level-shifted reproduced signal to the pre-amplifier.

Abstract: An updatable optical data storage disc for use with a laser includes a substrate and a recording layer. The substrate contains pre-recorded information in the form of concentric or spiral tracks of pits. Recordable tracks are positioned between adjacent pre-recorded tracks, whereby the tracks on the disc alternate in the radial direction. Laser light reflected from the recorded portions of the recording layer has a different phase than does light reflected from the unrecorded portions. This phase difference must be significant enough to be sensed by the detector. The difference in the reflectivity of the unrecorded and recorded portions of the recording layer should be minimized. The invention also includes a method and drive compatible with the disc.

Abstract: An optical disk is formed with grooves and lands for optically tracking an optical signal along a disk substrate. The lands and grooves are tracking guides on the surface of the disk substrate are coated with a recording film. The recording film varies in thickness over different portions of the tracking guides on the surface of the disk. A number of relationships and critical values may be determined by defining film thickness over the top of a land defined by (a), film thickness over a groove by (b), film thickness along a sidewall of a land by (c), groove depth from the top of a land to the bottom of a groove by (d1), and vertical film depth from the top of the film over a land to the top of the film over a groove by (d2). A difference in level (d2) of the recording film is preferably between 100-800 nm and a ratio (b/a) is preferably between 0.6-1.1. Also, a ratio (c/a) is preferably between 0-0.8.

Abstract: Methods and apparatus are provided for illuminating an optical disk in a multi-track optical disk reader. A laser beam is collimated and focused onto an area including multiple, adjacent data tracks on the optical disk. To minimize noise caused by interference resulting from the reflection of multiple beams from the optical disk the coherency of the laser beam is reduced. This is accomplished by one or more of the following techniques: passing the laser beam through a multi-mode optical fiber, combining laser beams from multiple independent laser sources, and modulating the laser operating current at high frequency.

Abstract: In mark length modulation recording, a mark end portion correction pulse train is added to a recording pulse train, or laser radiation with bias power is applied between the recording pulse train and laser radiation with cooling power or the mark end portion correction pulse train, furthermore, the start time of the cooling power radiation, the duration of the cooling power radiation, and the shape of the mark end portion correction pulse train are varied in accordance with the mark length to be recorded, further, in CAV mode, the start time of the cooling power radiation or the duration of the cooling power radiation is varied in accordance with disk radius position, and when the recording pulse train consists of a start pulse, an end pulse, and pulses between the start and end pulses, laser radiation with cooling power is applied, or laser radiation with bias power is applied between the recording pulse train and cooling power application, and when the recording pulse train is varied in accordance with mark

Abstract: The present invention provides a method for reducing noise using a plurality of recording copies. The present invention produces a master file with lower noise than the available recording copies, and avoids the problems of losing musical content caused by prior art pop and click removers. The system comprises a recording playback unit, a computer system with a sound input capability, and a high capacity storage system such as a CD recorder. In operation, a plurality of recording copies of a single recording are played on the playback unit. These recordings are digitized by the computer and a separate recording file is formed for each copy of the recording. The recording files are then synchronized. The samples from each of the recording files are then averaged to reduce the noise components.

Abstract: A device for removing a crosstalk component mingled from an adjacent track to a target track from a reproduction signal of the target track is provided for automatically adjusting a coefficient on which the amplitude of the reproduction signal of the adjacent track is adjusted for generating a crosstalk component signal. A crosstalk component signal generating unit 20 operates to generate a crosstalk component signal 20E or 20F by adjusting an amplitude of a signal 21a or 22a having a suppressed high frequency component of each reproduction signal ERF or FRF of the adjacent track with respect to the coefficient KE or KF. A subtracting unit 30 operates to output subtract the crosstalk component signal 20E or 20F from a main reproduction signal MRF for outputing a crosstalk-removed signal 8a.

Abstract: A power control system controls power of light emitted from a light source to a recording medium. The light having a first power is used to erase previous information from the recording medium and the light having a second power is used to record information in the recording medium in a recording operation. The power control system includes a detecting unit for detecting reflected light from the recording medium when the light source emits the light having the first power to erase the information from the recording medium. The detecting unit outputs a reflection signal corresponding to the reflected light. The power control system further has a control unit for controlling the first power of the light emitted from the light source so that a level of the reflection signal output from the detecting means is controlled at a predetermined target level.

Abstract: A super-resolution optical head device includes a diffraction grating having central and peripheral areas. The central area suppresses zero order diffracted light and produces .+-.1th order diffracted light. The peripheral area produces both zero order diffracted light and .+-.1th order diffracted light. The .+-.1th order diffracted light from the central and peripheral areas forms side light beams without an aperture. The side light beams form side spots on a recording medium. The side spots are not accompanied by side lobes because the side light beams do not have an aperture therein.

Abstract: An apparatus for use in an optical system in which information is read from a recorded wobbled groove of an optical medium by detecting first and second portions of a return beam in first and second detectors producing detected signals, respectively, the apparatus comprising:gain control circuit means coupled to the first and second detectors, respectively, and receiving the first and second detected signals therefrom;the gain control circuit means being responsive to the detected signals for producing a summation signal which is a function of the sum of the two detected signals;a first signal difference circuit coupled to the first and second detected signals for providing a difference signal; anda second signal difference circuit responsive to the difference signal and the summation signal for producing a wobbled groove information signal.

Abstract: A laser emission unit for use in an optical head performs a plurality of functions which are integrated. A laser beam from the laser emission unit mounted in a lens holder is emitted through an objective lens and is focused on an optical medium. A reflected beam from the optical medium returns through the objective lens and a diffraction grating to a signal detection circuit in the laser emission unit. Since the laser emission unit performs a plurality of functions, the space for various elements otherwise required in the optical head can be eliminated. The space for an additional light path for the reflected beam is also eliminated. Therefore, the size of the optical head is very small. Since the optical head can be assembled by using a small number of parts, the production costs can be reduced. Furthermore, the optical head can shield the noises by using the housing and/or the lens holder itself.

Abstract: A level sensor circuit compares a threshold level from a threshold value generator circuit with that of an input sampling signal to create a binarized pulsated signal. A change point detector circuit detects a change point of binary information indicated by the input pulsates signal or positions before and after the change point and thereby sends a change point detection signal(s) to a threshold level generator circuit. The threshold level generator circuit extracts from the sampling signals only ones at points of time when the change point detection signal is inputted from the change point detector circuit and then averages the extracted sampling signals with respect to time to generate a threshold level.

Abstract: A disc recording device for recording a first information signal and a second information signal, e.g. a pilot signal, on a disc-shaped recording medium comprises an optical pick-up having first and second laser diodes for recording the first and second information signals on the disc-shaped recording medium, a first modulator for modulating the first information signal at a first frequency, a first laser diode modulator for driving the first laser diode based on a signal outputted from the first modulator, a generator for generating the second information signal of a second frequency and a second laser diode modulator for driving the second laser diode based on the second 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: A light radiated from a light source is focused to provide a light spot on an optical disc. A central portion of the radiated light is shielded, and a peripheral portion of the radiated light is modulated to have an intensity decreasing in an outer periphery direction, respectively, by a light intensity modulator. Consequently, a diameter of the light spot is reduced, and side-lobes are suppressed. In place of the light intensity modulator, a light source filter and a second filter are used. A secondary light source is formed by focusing the radiated light. At a point of the secondary light source, the light source filter having a central portion of 0% and a peripheral portion of 100%, respectively, in light transmission intensity is provided. On an output side of a collimator lens, the second filter having central portion of 100% and a peripheral portion of 0%, respectively, in light transmission intensity is provided.

Abstract: A method and an apparatus for transmitting digital signals are disclosed. The input digital signal is converted into a plurality of blocks each having a finite time width and an finite frequency width. Signal components of at least some of the blocks are processed in a non-linear fashion, and the resulting non-linearly processed signal components are quantized. A recording medium on which encoded digital signals are recorded is also disclosed.

Abstract: A probe is displaced relative to a recording medium according to a drive voltage. A chip is provided at an end of the probe. The chip serves to form pits and projections on a surface of the recording medium according to a recording voltage (Vp2) and serves to output a current signal responsive to the pits and projections with a reproducing voltage (Vp1) applied. A voltage generator generates the recording voltage and the reproducing voltage based on address and data signals. A sample-hold unit samples at a specified frequency a current signal obtained from a no-recording area of the recording medium by the chip and produces an output voltage signal. A reproducing unit demodulates and reproduces increment and decrement of the current signal obtained from a recording area of the recording medium by the chip. A control unit controls recording and reproduction.

Abstract: The information recording and reproducing apparatus includes: a recording medium including a plurality of concavo-convex pits; a light source for emitting laser light; a section for changing an optical characteristic value of the laser light, using interaction between the laser light and the recording medium; and a light detector for detecting the optical characteristic value of the laser light after the interaction occurs, and then outputting a signal in response to the detected optical characteristic value. The section for changing the optical characteristic value includes an evanescent wave generating section for generating an evanescent wave from the laser light. The evanescent wave generating section changes the optical characteristic value in accordance with how much the concavo-convex pits of the recording medium influences the evanescent wave. Multivalued data is reproduced on the basis of the signal from the light detector.

Abstract: An optical disk device which uses a light spot for reproducing data, including photodetector, a decoder, and a non-linear equalizer provided between the photodetector and the decoder for correcting non-linear distortions in a reproduced signal from an optical disk. The non-linear equalizer includes a linear equalizer and a decision feedback equalizer provided after the linear equalizer. The non-linear equalizer includes a detector for detecting a signal on the basis of the output of the linear equalizer with the output of the detector being input to the decision feedback equalizer, the output of which is input to the detector along with the output of the linear equalizer in an additive manner.

Abstract: An optical pickup apparatus to produce two polarized beams to be irradiated onto a given track of a recording medium with neighboring each other. The optical pickup apparatus includes a laser light source for generating beams irradiated on a recording medium, a beam splitter for reflecting beams vertically and for transmitting the beam reflected from the recording medium, a double refraction polarization means for separating the beams into first and second polarized beams and for transmitting a reflected first and second polarized beams so as to have a same beam path, a polarization been splitter for reflecting the reflected first polarized beam passing and for transmitting the reflected second polarized beam, and at least one photodetecting means for separately receiving the reflected first and second polarized beams. The optical pickup apparatus is able to reduce detection errors resulting from some defects made on the surface of the recording medium.

Abstract: An optical information reproducing apparatus having an optical recording medium in which information is recorded in a state that it is optically reproduced, and an optical head for reproducing the recorded information from the recording medium while moving relatively to the recording medium. In the apparatus, images are formed on the recording medium by two laser beams emitted from a light source of the optical head, and the difference between the two laser beams transmitted through the recording medium or reflected by the recording medium is detected.

Abstract: An apparatus for playback of an optical recording medium where data are recorded after combined calculation of a difference signal and a sum signal generated by detecting reference patterns and the return light reflected from the optical recording medium. The recording medium has tracks formed at such a pitch that at least two tracks are scanned simultaneously by a spot of a light beam irradiated onto the recording surface. Each track has data composed of wobble pits formed at positions deviated from the track center and a multiplicity of pits formed exactly on the track center, wherein the multiple pits and the wobble pits are disposed successively. The apparatus comprises an optical detector and a signal discriminator. The optical detector has first and second adjacent light receiving areas divided along the tangential direction of the tracks and serving to receive the return light reflected from the optical recording medium.

Abstract: An optical information reproducing apparatus for reproducing information from an optical recording medium that has a recording and reproducing and information-rewritable track region, which is composed of a header region having information, such as a sector start mark, track number and sector number, in a pit shape formed when the recording medium has been manufactured and a recording and reproducing user data region that has no pit and enables information to be recorded and reproduced, the optical information reproducing apparatus having a semiconductor laser output control circuit for controlling a quantity of a semiconductor laser beam to be emitted to a predetermined value such that a detected quantity of an emitted semiconductor laser beam is obtained in only the user data region when the quantity of the laser beam emitted by a semiconductor laser that irradiates the recording medium with a semiconductor laser beam is detected.

Abstract: An optical head includes an irradiating device for irradiating a recording medium with a light beam, a separating device disposed in an optical path between the recording medium and the irradiating device, which is provided for separating a portion of the light beam traveling from the irradiating device to the recording medium, and a detecting device for detecting the portion of the beam separated by the separating device, which has a plurality of sensor portions.

Abstract: A detected image output by a holographic storage system is comprised of a grid of dark and light spots, representing high and low logic states. The image is superimposed onto a grid of detector elements or pixels in a detector. Each of the data bits is represented by a bit image or bixel, which is oversampled by a factor of two along the x- and y-axis by the pixels. A state machine is utilized to generate expected states for each of the pixels and then an energy shifting operation performed to shift energy from a pixel having a higher than expected output value to a pixel having a lower than expected output value. This operation can result in energy being shifted from the left to the right or the right to the left. Column synchronization is performed by defining a set of pixels in a row for each column as a segment with an associated parity bit and row number. Each segment may be output as validated, or may be retained in a buffer until all previous segments in a row have been accumulated and/or output.

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 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 optical information storage apparatus includes a differential type optical switch element, and an optical fiber. The optical switch element shifts from a non-emission state to an emission state upon reception of an optical input. The optical fiber constitutes a first optical path. The optical fiber receives an optical output emitted from the optical switch element through at least one end face, guides the optical output, and causes an output beam to be incident, as the optical input, onto the optical switch element.