Abstract: Methods, systems, and computer programs encoded on computer storage medium, for polling a battery management unit (BMU) that is coupled to a battery power source, the polling including identifying parameters associated with the battery power source and are stored by registers; determining that an AC power source is not actively providing power to the IHS; determining that the battery power source does not support dynamic battery power technology (DBPT); determining that the RSoC of the battery power source is greater than a first threshold percentage and less than a second threshold percentage; determining an updated processor peak power (PPP) value based on i) the RSOC, ii) a minimum PPP of the processor at the first threshold percentage, and iii) a maximum PPP of the processor at the second threshold percentage; and updating the registers based on the updated PPP.

Abstract: Provided is a defect detection device including an illumination unit including a condenser lens and a plurality of light beam synthesis units, and a detection unit detecting scattered light generated on a sample by the illumination unit. The condenser lens condenses a plurality of light beams, emitted onto the sample and having substantially the same wavelength and substantially the same polarization, on the sample. The plurality of light beam synthesis units bring the plurality of light beams close to each other and make the light beams have light paths parallel to the optical axis of the condenser lens.

Abstract: A first optical receiver circuit in an optical receiver IC, which composes an optical disk device, generates a first voltage signal VS1 indicating an amount of light of a laser beam oscillated in a multimode. A second optical receiver circuit generates a second voltage signal VS2 indicating an amount of light of an optical feedback from an optical disk. A binarization circuit extracts a band component corresponding to a predetermined frequency in VS1, and binarizes the band component, thereby obtaining a digital signal. A delay element delays a phase of the digital signal by time equivalent to a phase difference between VS1 and VS2, and outputs the phase delayed signal as a timing signal. A sample hold circuit (S/H) samples and holds the VS2 in synchronization with the timing signal. Further, A LPF eliminates a band component corresponding to the frequency from an output signal of the S/H.

Abstract: A data recording and reproducing device includes: a light emitting element that generates light and emits the light toward an optical recording medium; a light emission control section that feedback-controls an emitted light quantity from the light emitting element; a light attenuating drive section that includes a light attenuating section, and inserts the light attenuating section into an emission path of the light when reproducing data from the optical recording medium and retracts the light attenuating section from the emission path when recording data onto the optical recording medium; and a shock detecting section that detects a shock of a magnitude causing the light attenuating drive section to switch between the insertion and retraction. When the shock detecting section detects the shock during data recording, the light emission control section lowers a control target value of the emitted light quantity from a value set at the time of shock detection.

Abstract: A first optical receiver circuit in an optical receiver IC, which composes an optical disk device, generates a first voltage signal VS1 indicating an amount of light of a laser beam oscillated in a multimode. A second optical receiver circuit generates a second voltage signal VS2 indicating an amount of light of an optical feedback from an optical disk. A binarization circuit extracts a band component corresponding to a predetermined frequency in VS1, and binarizes the band component, thereby obtaining a digital signal. A delay element delays a phase of the digital signal by time equivalent to a phase difference between VS1 and VS2, and outputs the phase delayed signal as a timing signal. A sample hold circuit (S/H) samples and holds the VS2 in synchronozation with the timing signal. Further, A LPF eliminates a band component corresponding to the frequency from an output signal of the S/H.

Abstract: The present invention relates to an optical recording apparatus capable of recording information on an optical record carrier. Radial tracking control is performed by the 3 spot differential push pull (PP) method. The optical recording apparatus has means for obtaining a first and second difference signal from detection signals of a reflection of a main light beam (C) and a first and a second sub light beam (A,B), and means for subtracting the second difference signal from the first difference signal so as to obtain a tracking error signal (TES). The second difference signal is adjusted by a gain factor (g) so as to compensate for a difference in intensity between the reflected light of the first and the second sub light beams during information writing. In particular, a solution may compensate for the difference in the reflections for the first and second sub light beam (A,B) so that a possible radial offset is avoided.

Abstract: An optical semiconductor device of the present invention includes: a light-receiving element which converts light into an electric signal; an amplifier circuit having an input terminal to which the light-receiving element is connected, and which amplifies the electric signal; a connection wire to which the signal amplified by the amplifier circuit is outputted; an output circuit having an input terminal to which the connection wire is connected, and which performs current amplification on the signal amplified by the amplifier circuit and outputs the current-amplified signal to an output terminal; a feedback resistor connected between the input of the amplifier circuit and the output terminal; and a shield wire connected to a potential outputted from the output circuit or a potential resulting from a voltage follower of the potential outputted from the output circuit, and which shields the connection wire from noise.

Abstract: A method of and an apparatus for controlling a power of a light emitter in an optical disc drive to stabilize a servo control operation by efficiently compensating a slow tail effect occurring in a photodiode monitoring outputs of the light emitter are provided. The method includes: detecting an intensity of a laser signal reflected from a recording medium; normalizing the reference value using the detected value; and adjusting the reference value using the normalization result.

Abstract: An optical element is provided in which in a lens surface substantially perpendicular to the optical axis of the lens, there is embedded a conductive member whose diameter or width is smaller than the diameter of an optical spot incident upon the lens surface. The optical element is used in an optical head which reads a signal by illuminating an optical recording medium with a reading light. The basic principle of this optical head is such that a subtle phase change of the light is detected which is caused by the electromagnetic interaction between the conductive member embedded in the optical element and a conductive material on the surface of the optical recording medium. For example, the interference between return light beams from the optical recording medium is used to read a signal. Alternately,.

Abstract: A polarization-sensitive beam splitter comprising at least one transparent wedge-shaped element of a birefringent material is made by providing each one of two substrate plates with an orientation layer, whereafter the substrate plates are arranged with their orientation layers facing each other while forming a wedge-shaped interspace. The interspace is filled with a liquid crystalline monomer composition, which is subsequently cured while forming a wedge-shaped element of a uniaxially oriented polymer material. After possible removal of the substrate plates, two or three of such wedge-shaped elements can be joined to a Wollaston prism for use in the pick-up element of a magneto-optical recording system.

Abstract: There is provided a three-dimensional imaging system (2), including a first camera (6) and a second camera (8), both facing a field of view of two-dimensional images and a normally open, fast gating device (12) interposed between the second camera (8) and the field of view (14 and 26). The system further includes a frame grabber (10) connected to the first and the second camera, and a computer (14) for receiving signals representing, pixel by pixel, light intensities of an image during a predetermined period of time and signals representing same pixel by pixel of light intensities arriving at the second camera until the fast gating device (12) is closed, and for determining three-dimensional imaging signals therefrom to eventually be displayed. A method for producing three-dimensional imaging is also provided.

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

Abstract: An optical pickup having a beam shaping device for changing an oval-shaped light beam emitted from a light source into a circular light beam, and an astigmatic difference correcting device for correcting the astigmatic difference of the light is provided. The beam shaping device is a cylindrical lens arranged between the light source and a beam splitter, having a convex cross-section, for converging the incident light, e.g., with respect to an X-axial direction. The astigmatic difference correcting device is an astigmatism lens arranged along an optical path between the cylindrical lens and a light path changing device, as a concave lens, for linearly passing light of a certain direction and diverging light of other directions.

Abstract: In laser feedback systems of an optical memory the most suitable feedback gain value depends on the type of optical disks used. According to the invention a system and a method is provided which finds by way of an iteration a suitable maximum feedback gain value so that the feedback system does not oscillate. The method consists in starting with a low gain value for driving a laser diode, increasing the gain value by small amounts until an oscillation detecting unit detects that the laser feedback system is oscillating. Then the gain value is reset to the previous value or a little bit more. Then the laser feedback system is again in a non-oscillating area with a suitable maximum gain value. This iteration is performed by a system consisting mainly of a laser diode, a photodiode for detecting the reflected light, and an oscillation detecting unit which controls a gain controller. This gain controller sets the gain on a multiplier which drives the laser driver for the laser diode.

Abstract: A laser power supply control circuit may, when the power supply is initially turned on, temporarily permit an excessive supply voltage which may damage the laser. To prevent that, but without restricting the operating range or speed of response of the control circuit, the invention provides a sensing circuit for deriving a sensor signal indicative of a change in the loop gain of the control circuit when it departs from its normal operating mode. The sensor signal is used to prevent the power supply control signal from increasing excessively after a temporary reduction in supply voltage, but permits the control signal to operate substantially immediately when the supply voltage returns to its normal operating range.

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

Abstract: A trial writing operation is performed on a phase-change optical disc using write and erase light-emitting powers, which together are varied according to predetermined variation ratios respectively. Signals relevant to said trial writing operation are reproduced from said disc. Optimum ones of the write and erase light-emitting powers are determined using the thus-reproduced signals. The predetermined variation ratios for the write and erase light-emitting powers may be the same as each other. Alternatively, the trial writing operation may be performed on a phase-change optical disc using write and erase light-emitting powers which are individually varied according to predetermined variation ratios respectively.

Abstract: A positioning system of an optical disc apparatus includes focus error detecting part for detecting a focus error signal as a focal shift of a light spot related to an information recording surface of an optical disc, light spot moving part in the direction intersecting substantially perpendicularly to the optical disc surface, first digital arithmetic part for receiving the focus error signal and outputting a first control signal, second digital arithmetic part for receiving the focus error signal and a specified third control signal, performing arithmetic operations of a disturbance observer and outputting a second control signal, adding circuit for adding the first control signal and the second control signal and outputting the third control signal, drive circuit for driving the light spot moving part in a direction intersecting perpendicularly to the disc surface by the third control signal, wherein the first and the second digital arithmetic circuit perform arithmetic operations at different sampling per

Abstract: In a data reproducing apparatus, an optical pick-up is radially movable with respect to, and recovers information from, an information storage member. A motor rotates an information storage member. A spindle servo controls the speed of rotation of the motor in response to a timing signal, to provide constant linear velocity between the information storage member and the optical pick-up. A signal processor creates a recovered timing signal from the information recovered by the optical pick-up, and passes the recovered timing signal to a switching circuit. During normal playback, the switching circuit passes the recovered timing signal to the spindle servo as the timing signal. During search, a controller directs an oscillator to output a reference timing signal to the switching circuit. A controller directs the switching circuit to pass the reference timing signal to the spindle servo as the timing signal while the optical pick-up is moving radially with respect to the information storage member.

Abstract: According to an aspect, to realize a transient correction circuit capable of performing a high-speed operation without being affected by low-frequency noise and allow to remove only the low-frequency noise without changing a reproducing waveform, an output from a HPF for removing the low-frequency noise of a reproduced signal is supplied to a waveform correction circuit for correcting the transient of the reproduced signal, which is generated by the HPF. The waveform correction circuit is constituted by a LPF, an adder for adding an output from the LPF and the output from the HPF, and a quantization circuit for quantizing an output from the adder. The HPF and the LPF have the same time constant.

Abstract: An optical write/read head is provided with apparatus for monitoring the output of a read/write laser so that the laser power may be appropriately adjusted to maintain a desired level. The apparatus features a partially reflective, partially transmissive surface in the optical path between the laser source and the recording medium for reflecting a small percentage (e.g., 4% 6%) of the laser output to a photodetector forming part of an electrooptical feedback loop for controlling the laser power. Preferably, the laser power-controlling photodetector is located adjacent the photodetector used to develop the recording signal, and the partially reflective, partially transmissive surface is tipped a few degrees from normal to the optical axis. Also preferred is that the partially reflective, partially transmissive surface constitutes the rear surface of a quarter-wave plate used to rotate the angle of polarization of the read/write beam to avoid optical feedback to the laser cavity.

Abstract: In an optical recording apparatus light is directed to and reflected from a recording medium to recover recorded information. The intensity of direct and reflected light is measured and the ratio of the measured values is used to control the intensity of the light source to maintain the intensity of reflected light substantially constant.

Abstract: An optical head structure, employed in an optical device, in which light radiated from a predetermined light source is projected onto a predetermined recording medium through a light splitting member is disclosed. Part of the light is directed to the outside of the light splitting member and converged so as to be detected by a predetermined light detecting member. The light directed to the outside of the light splitting member is reflected at a predetermined angle by a predetermined light reflecting member. Thus, it becomes possible to make the whole volume of the optical device smaller. Also, the number of parts required in the optical head structure can be decreased.

Abstract: An apparatus and method for providing differential detection and source noise subtraction in data signals read from magneto-optic (MO), write-once (WO) or other types of optical storage media using an incident radiation beam. A source monitor signal is generated by detecting radiation from an optical source providing the radiation beam. An error detector generates an error signal corresponding to a difference between the source monitor signal and a reference signal. A power level of the radiation beam is adjusted in response to the error signal. A data signal generator is adapted to receive a return beam resulting from application of the radiation beam to the medium and to generate a WO data signal from the return beam. A signal combiner combines the data signal and the source monitor signal to provide a compensated WO data signal.

Abstract: An optical disc player adapted to read an optical disc having a plurality of pits and lands representative of information stored on the optical disc; the optical disc being at least in part unmetallized. The player includes a semiconductor laser for generating a variable power laser beam, the power of the beam being controlled by a control signal applied to a control terminal of a semiconductor laser driver. A focusing servo is provided for focusing the beam on the optical disc such that a portion of the beam is reflected back from the optical disc indicative of the pits or lands. The portion of the beam reflected back from the optical disc being substantially less from unmetallized portions of the disc than from metallized portions of the disc. The focusing servo has a focal point constrained to lock on a pit plane of the optical disc.

Abstract: An optical pickup device for an information recording and/or reproducing apparatus in which fluctuations in polarization film characteristics due to the variable incident angles of the light beam to the beam splitter may be reduced to prevent C/N characteristics from being lowered. The optical pickup device includes an objective lens 3 for converging a light beam L from a laser light source 1 to a magneto-optical disc 2, a beam splitter 8 arranged on a light path between the laser light source 1 and the objective lens 3 for guiding a return laser light beam Lr from the disc to outside of the light path, and a photodetector 4 for detecting the return light beam Lr guided by the beam splitter 8 to outside of the light path. The beam splitter 8 is arranged at a portion in the light path between the laser light source 1 and the objective lens 3 in which the light beam L from the laser light source 1 is a divergent light beam.

Abstract: An offset pulse having a polarity opposite to that of a large tracking error pulse that occurs in response to an operation mode changeover is added to a tracking error signal. The offset pulse has a duration starting immediately before the operation mode changeover and partially overlaps with the tracking error pulse. The offset pulse is generated so as to rise at a timing that is determined based on a wobble signal extracted from the tracking error signal.

Abstract: An optical recording and reproducing apparatus records two rows of a plurality of pit patterns with respect to one track by modulating two light beams and by converging the modulated two light beams in parallel onto the track. The plurality of pit patterns are detected and judged by a multiple hologram on which reflected object waves of all kinds of pit patterns are recorded, thereby enabling to carry out recording of information. With the arrangement, since multiple values recording and reproducing can be carried out with respect to a magneto-optical disk, the recording capacity becomes greater than the conventional case and the reproduced signal having little crosstalk can be obtained according to the present way of reproducing.

Abstract: In an optical disk reproducing apparatus including an optical disk, an optical disk rotating device, a light source for radiating a reproduction beam on the optical disk, a light condensing device for condensing the reproduction beam on the optical disk, a detection device for detecting a beam passing through or reflected by the optical disk, and a position detection device for detecting a reproduction beam condensing position, or in a method using this apparatus, the intensity of the reproduction beam is changed in accordance with the reproduction beam condensing position on the optical disk to perform reproduction.

Abstract: With an optical playback device, for example, with a compact disk player, care should be taken to see that the light beam scanning the data radiates as perpendicular as possible onto the disk. However, as a consequence of disk slap or chattering, the radial and the tangential angles alter during every revolution of the disk. As a result of the tolerances in the disk and the device, the optical axis deviates from the perpendicular in many cases. In order to regulate the radial angle .phi.R and the tangential angle .phi.T, under which the light beam strikes the disk, the data signal is demodulated in an amplitude demodulator. The regulating signal UR=C* sin .phi.* cos .alpha. for the radial angle .phi.R and the regulating signal UT=-C* cos .phi.* sin .alpha. for the tangential angle .phi.T are generated from the amplitude C and the phase position .phi. of the demodulated data signal.

Abstract: A control method and controller for an optical storage drive including: an optical head having a laser light source for applying light to an optical disk and a detector for receiving reflected light from the optical disk; and a seek mechanism for positioning the optical head on the optical disk. The control method includes: measuring a drive current value with which the laser light source provides a predetermined light power value by an emission adjustment; writing the measured drive current value into a non-volatile memory as an initial value; adjusting the emission of the laser light source so that it provides the predetermined light power value; and comparing the drive current value with which the emission adjustment has been made with the initial value stored in the non-volatile memory. Also disclosed is a control method which measures and stores a write power value providing optimum write performance in a non volatile memory for controlling the power of the laser light source with the measured value.

Abstract: Various optical amplifier configurations are disclosed. In one configuration, an optical amplifier provides an amplified output signal through use of a pumping device. The output signal is split to an output and a feedback input. The feedback signal is converted to a current which is sensed by a controller. The controller adjusts the amount of current to the pumping device in various instances. In one instance, the current is controlled to prevent overdriving the pumping device. In another instance, the current is controlled to maintain the output signal at a substantially constant level. In another configuration, the optical amplifier is coupled to a ratio computation block which measures the operating efficiency of the pumping device. Additional components detect an undesirable efficiency and provide a warning of the same.

Abstract: A recording and/or reproducing apparatus is disclosed in which informational signals are recorded and/or reproduced by irradiating an optical disc 202 with a light beam from an optical pick-up device 1 through an recording and/or reproducing opening 205 which is formed in a disc cartridge 202 which rotatably houses an optical disc 203. The optical pick-up device 1 which is used for the recording and/or reproducing apparatus comprises a light source and an objective lens 5 for converging the light beam from the light source upon the signal recording area of the optical disc 203. When recording and/or reproducing of informational signal on and/or from the optical disc 203 is performed by the optical pick-up device 1, only the objective lens 5 is moved into the disc cartridge 202 via the recording and/or reproducing opening 205 formed on the disc cartridge 202 to shorten the distance between the objective lens 5 of the optical pick-up device 1 and the disc 203.

Abstract: A video signal recording/reproducing device has at least a frequency modulating unit which FM modulates information to be recorded on an optical disk memory, a laser driving pulse generating unit for generating a laser driving pulse derived from the frequency-modulated signal generated by the frequency modulating unit and for modifying the duty factor of the laser driving pulse in accordance with the linear velocity of the optical disk memory where recording is taking place; and a recording unit for controlling the laser power during recording to an optimum value in accordance with the linear velocity of the optical disk memory where recording is taking place. This arrangement enables reduction of the minimal length of recording bits resulting in reproduced signals of a level sufficient for obtaining reproduced images of a fine quality addition enables increase of the recording capacity of the optical disk memory.

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: A optical signal from the input terminal 6a is amplified and goes through the optical fiber doped with rare earth. The excitation lights from the excitation light sources 2 and 3 are synthesized at the optical coupler 4 and outputted to the optical fiber doped with rare earth 1 through the optical coupler 5. A part of the light is branched from the optical coupler 11 to optical receiver 14 through the band pass light filter 13. The optical receiver 14 converts the received optical signal to an electrical signal and outputs it to the error signal output circuit 114. The receiving current is amplified in the error signal output circuit 114 and branched to the excitation light source output control circuits 9 and 10.

Abstract: An optical or magneto-optical disk storage which automatically adjusts a recording/reproducing level of a number of kinds of optical or magneto-optical disks having different recording/reproducing levels to an optimum recording/reproducing level. The optical or magneto-optical disk storage has an attenuator which applies a predetermined attenuation amount to a reproduced signal reproduced from an optical or magneto-optical disk so as to attenuate the reproduced signal, or intensity adjusting means for adjusting the intensity of a laser beam used for recording and/or reproducing. The optical or magneto-optical disk storage detects an amplitude of the reproduced signal and feed-back-controls the attenuation amount or intensity of the laser beam in accordance with the detected amplitude.

Abstract: A disk recording and reproducing apparatus using two light beams has a disk driving section for loading a disk-shaped record medium having recording tracks and for rotating the disk-shaped record medium, an optical system having a light beam generating source, a light beam splitting device for splitting a light beam to provide at least a main beam and a sub beam, an optical path forming device for respectively causing the main beam and the sub beam to become incident on two adjacent recording tracks in the disk-shaped record medium loaded on the disk driving section and a photo-detecting device for detecting the condition that at least the sub beam from the disk-shaped record medium loaded on the disk driving section is affected by the recording track.

Abstract: An optical data storage apparatus and disc in which information is stored in the form of multiple submicron depths at information-storage sites on the disc surface. The depth information is read by directing a focused laser beam onto the storage sites, back reflecting a portion of the reflected beam into the laser cavity, and converting power fluctuations in the laser beam to submicron distance measurements.

Abstract: This invention relates to a technique for obtaining a desired laser power. In write mode the laser power in an optical disk drive is determined in accordance with a DAC value which controls a power supply for the laser, but the correlation between the laser power and the DAC value significantly varies depending on the efficiency of the individual laser diode or laser oscillator. Because the laser power in read mode has been adjusted to a predetermined value during manufacturing, the DAC value which generates the same laser power as the reading laser power is known and is used to generate the desired laser power, such as the writing laser power.

Abstract: An optical disc apparatus comprises a light source, an optical disc, a beam splitting element for splitting a light beam from the light source into a first beam and a second beam, a light detection element for detecting the second beam and outputting a detection signal, a control circuit for controlling an intensity of the light beam from the light source on the basis of the detection signal from the detection element, so that an intensity of the light beam from the light source is uniform, and an optical system through which the first beam passes, to reproduce the information recorded on the optical disc.

Abstract: This invention relates to a method of determining the optimal recording power for an optical disk apparatus.

Abstract: A method is described which enables automatic determination of the monitor sensitivity of a radiation emitting arrangement (in particular a laser diode and photodiode arrangement), which monitor sensitivity relates a level of a monitor signal (I.sub.M) generated by the arrangement to a corresponding optical output level (O.sub.L) of the arrangement. The method comprises the steps of: (i) supplying a varying drive signal (I.sub.L1,I.sub.L2) to the arrangement and measuring the rate of change (.DELTA.I.sub.M /.DELTA.I.sub.L) of the monitor signal (I.sub.M) with respect to the supplied drive signal (I.sub.L); and (ii) combining the measured rate of change with an assumed differential efficiency (k) of the arrangement to determine the monitor sensitivity (O.sub.L /I.sub.M) of the arrangement. The provision of a control system able to implement such a method eliminates the need for a factory adjustment in the manufacture of apparatus such as optical recording and/or reproducing apparatus.

Abstract: A laser beam control circuit for an optical recording/reproducing apparatus, which controls the intensity of a laser beam striking a magneto-optical disc. The control circuit controls the injection current to a laser diode to provide high intensity for recording and low intensity for reproducing, providing a smooth transition between the high and low intensity states, and avoiding any excessive transition current. The control circuit monitors the output power of the laser diode and maintains it at a first value in the reproducing mode and a second value in the recording mode, and further controls the output power so that even during switching, the output power does not exceed the second level. This is done by supplying a compensating reference voltage to the recording power control loop during the reproducing mode, so that the output of the recording error amplifier does not change abruptly when the operating mode is switched to the recording mode.

Abstract: A wavelength selective optical recording and reproducing device has a reference wavelength in a marker hole of a medium. The optical detector is adapted to detect light which is reflected from or transmitted through the marker hole. A phase detector detects the phase of an output of the optical detector by using a high frequency signal as a reference to obtain a signal indicative of the deviation of the wavelength of the output from a desired wavelength. A wavelength regulator is responsive to the wavelength deviation to control the wavelength of the light source to be the desired wavelength.

Abstract: An optical recording apparatus of the type employing a read/write laser adapts the recording light beam to various linear speeds of the recording disk by jointly controlling both the beam power and the duty ratio of the recording signal in accordance with the radial position of the beam spot on the disk.

Abstract: An optical disk and a method of recording, reproducing or erasing information on the disk by using laser beams. The optical disk is provided thereon with grooves each having a V-shaped groove in the radial directioin. At least two laser beams are focused on two adjoining slants of each V-shaped groove so that these two slants are used concurrently for high-density recording reproducing or erasing of high-quality information.

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: A focused light beam is projected upon an optical recording medium through an optical system in an optical pickup, and a light reflected from the recording medium is received to detect a focus error signal and a tracking error signal. Further, the focus control and the tracking control are both achieved through a servo feedback loop in response to the detected focus and tracking error signals. In this optical information recording and reproducing system, track formats are provided from which lights of different intensities are reflected, the track formats are discriminated by a projection position detecting circuit, and the focusing and tracking operations are controlled by selectively adjusting the gain of the servo feedback system according to the detected track format, so that the control operation is stable in recording or reproducing information data to or from a recording medium of a high density type, in particular.

Abstract: In an optical head of an optical memory device which records, reproduces or erases information onto or from a recording medium by applying a laser beam to the recording medium, a beam splitter is disposed in an optical path to conduct a portion of the laser beam emitted from a laser device to a light detector. In accordance with a detected value from this light detector, the influence of a stray beam generated in an optical system is removed from a servo error signal.