Abstract: Provided is a recording apparatus including a self-excited oscillation semiconductor laser that has a double quantum well separate confinement heterostructure and includes a saturable absorber section to which a negative bias voltage is applied and a gain section into which a gain current is injected, an optical separation unit, an objective lens, a light reception element, a pulse detection unit, a reference signal generation unit, a phase comparison unit, a recording signal generation unit, and a control unit.

Abstract: Provided is a recording apparatus including a self-excited oscillation semiconductor laser that has a double quantum well separate confinement heterostructure and includes a saturable absorber section to which a negative bias voltage is applied and a gain section into which a gain current is injected, an optical separation unit, an objective lens, a light reception element, a pulse detection unit, a reference signal generation unit, a phase comparison unit, a recording signal generation unit, and a control unit.

Abstract: A laser device includes a semiconductor laser, a signal generating circuit generating a pulse signal for driving the semiconductor laser, an amplifying circuit amplifying the pulse signal, and a control circuit unit provided between the amplifying circuit and the semiconductor laser and controlling the pulse signal by letting alternating-current components of the pulse signal pass through and removing at least part of direct-current components of the pulse signal.

Abstract: A recording apparatus for recording information on an optical recording medium includes a mode-locked laser unit that includes a semiconductor laser emitting a laser beam for recording the information on the optical recording medium, and an external resonator, an optical modulation unit that amplifies and modulates the laser beam emitted from the mode-locked laser unit, a recording signal generation unit that generates a recording signal based on a reference signal from a drive of the optical recording medium, and a modulation unit that generates a modulation signal for driving the optical modulation unit by latching the recording signal using a laser clock generated by an oscillation pulse of the laser beam emitted from the mode-locked laser unit.

Abstract: A recording apparatus, which records information in an optical recording medium, includes: a mode-lock laser unit including a saturable absorber section that applies a bias voltage, a gain section that feeds a gain current, a semiconductor laser that emits laser light used to record the information on the optical recording medium, and an external resonator; an optical modulation unit performing amplification modulation on the laser light emitted from the mode-lock laser unit; a reference signal generation unit generating a master clock signal and supplying a signal synchronized with the master clock signal to the gain section of the semiconductor laser; a recording signal generation unit generating a recoding signal based on the master clock signal; and a driving circuit generating a driving pulse used to drive the optical modulation unit based on the recording signal.

Abstract: A laser device includes a semiconductor laser, a signal generating circuit generating a pulse signal for driving the semiconductor laser, an amplifying circuit amplifying the pulse signal, and a control circuit unit provided between the amplifying circuit and the semiconductor laser and controlling the pulse signal by letting alternating-current components of the pulse signal pass through and removing at least part of direct-current components of the pulse signal.

Abstract: A reproducing apparatus for reproducing channel data from a recording medium using the ITR includes a reading unit reading an information signal recorded on the recording medium; a phase interpolator interpolating a phase of the information signal read on the basis of a phase error signal sent as a feedback; a first waveform equalizer equalizing a waveform of the phase-interpolated information signal while keeping the phase of the information signal fixed; a phase-error-signal generator generating the phase error signal to be sent as a feedback to the phase interpolator on the basis of the information signal whose waveform has been equalized by the first waveform equalizer; a second waveform equalizer equalizing the waveform of the phase-interpolated information signal without limiting a phase change; and a decoder generating the channel data by decoding the information signal whose waveform has been equalized by the second waveform equalizer.

Abstract: A laser driving device includes: a pulse signal generating unit that, after a voltage has risen from a predetermined reference voltage to a predetermined output voltage and a time of a sum of an oscillation period of relaxation oscillation and a light emission start time in a predetermined laser diode has nearly elapsed, generates a pulse signal having a waveform that falls divisionally in two or more stages from the output voltage to the reference voltage; and an output unit that generates a laser drive signal by performing signal processing on the pulse signal and outputs the signal to the laser diode.

Abstract: A method for cleaning a disk-shape glass substrate, which comprises rotating the disk-shape glass substrate on its center with its main surface vertical, and making a cleaning fluid irradiated with ultrasonic waves run down on the outer peripheral edge surface of the rotating glass substrate.

Abstract: An optical information reproduction apparatus for reproducing a recording signal by irradiating a light beam onto a recording surface of an optical information recording medium having at least two information recording layers and by receiving reflected light of the light beam is provided. The optical information reproduction apparatus includes an extraction section for extracting an envelope signal of a reproduction signal when the reproduction signal reproduced by focusing the light beam onto one information recording layer in the plural information recording layers has been modulated by interlayer crosstalk from another information recording layer; and a distortion correction section for correcting the distortion of the target reproduction signal caused by the interlayer crosstalk by gain-adjusting the reproduction signal containing DC components so that the envelope signal becomes constant.

Abstract: There are disclosed a method and device for polishing a metal ring, which is capable of polishing a side edge of the metal ring without performing barrel polishing or polishing by grinding stones. Subsequently to a projecting step of projecting a metal ring W by clearing means 6, a first brush polishing step of polishing one edge of the metal ring W by a polishing brush 60 is performed. Subsequently, an inverting step of inverting the metal ring W whose one edge is polished by the first brush polishing step is inverted by the inverting means 10 is performed. Subsequently, a second brush polishing step of polishing the other edge of the metal ring W which is inverted by the inverting step by the polishing brush 60 is performed. Moreover, a clearing step of clearing the metal ring whose other edge is polished by the second brush polishing step by clearing means 7 is performed.

Abstract: A reproducing apparatus for reproducing channel data from a recording medium using the ITR includes a reading unit reading an information signal recorded on the recording medium; a phase interpolator interpolating a phase of the information signal read on the basis of a phase error signal sent as a feedback; a first waveform equalizer equalizing a waveform of the phase-interpolated information signal while keeping the phase of the information signal fixed; a phase-error-signal generator generating the phase error signal to be sent as a feedback to the phase interpolator on the basis of the information signal whose waveform has been equalized by the first waveform equalizer; a second waveform equalizer equalizing the waveform of the phase-interpolated information signal without limiting a phase change; and a decoder generating the channel data by decoding the information signal whose waveform has been equalized by the second waveform equalizer.

Abstract: An optimum performance is achieved relative to write-once type optical recording mediums on which information is recorded by means of a blue-violet semiconductor laser. An optical disc recording/reproduction apparatus 10 comprises an LD control section 17 adapted to control the irradiation power of a laser when writing data. If the cycle of the channel clock is T, when forming a recording mark having a length of n×T (n being an integer not smaller than 2), a pulse beam is irradiated onto the write-once type information recording medium for n/2 times (decimals, if any, being to be rounded down). When forming a recording mark having a length of not smaller than 6T and even number times of T, a pulse beam is irradiated for n/2 times with all the intermediate pulse beams synchronized with the phase of the channel clock except the leading pulse beam and the tail end pulse beam.

Abstract: A method for cleaning a disk-shape glass substrate, which comprises rotating the disk-shape glass substrate on its center with its main surface vertical, and making a cleaning fluid irradiated with ultrasonic waves run down on the outer peripheral edge surface of the rotating glass substrate.

Abstract: The focus is moved from a first layer (L0) to a second layer (L1) of a double-layered optical disk by stopping a control loop operation and applying acceleration pulses for an interlayer jump to a two-axis electromagnetic actuator. Here, switching timing between acceleration and deceleration for an interlayer jump is generated based on the rate of change of a SUM signal obtained from a light-sensitive element (27), the SUM signal is distinguished by a specific threshold TH, and an S-shaped error signal is distinguished by thresholds THH and THL with different positive/negative level, thereby performing a pull-in operation of focus control. In addition, at the time of the interlayer jump, a liquid crystal element (23) for correcting the spherical aberration is optimized in advance for the cover layer thickness of the target layer L1.

Abstract: There are disclosed a method and device for polishing a metal ring, which is capable of polishing a side edge of the metal ring without performing barrel polishing or polishing by grinding stones. Subsequently to a projecting step of projecting a metal ring W by clearing means 6, a first brush polishing step of polishing one edge of the metal ring W by a polishing brush 60 is performed. Subsequently, an inverting step of inverting the metal ring W whose one edge is polished by the first brush polishing step is inverted by the inverting means 10 is performed. Subsequently, a second brush polishing step of polishing the other edge of the metal ring W which is inverted by the inverting step by the polishing brush 60 is performed. Moreover, a clearing step of clearing the metal ring whose other edge is polished by the second brush polishing step by clearing means 7 is performed.

Abstract: After making such adjustment that an a main push-pull signal MPP offset can be made zero when a main beam is positioned at the center of a main photoreceptor, using electric signals E and F photoelectrically converted by one of two two-divided side beam photoreceptors and electric signals H and G photo-electrically converted by the other thereof, a side push-pull signal SPP including a constant ? is determined for allowing respective (F??E) and (?H?G) offsets to be made zero and is calculated according to the formula, SPP?(F??E)+(?H?G). From this SPP signal and the main push-pull signal MPP, a differential push-pull signal DPP is then calculated, thereby allowing stable tracking control to be carried out, even during recording.

Abstract: An optical information reproduction apparatus for reproducing a recording signal by irradiating a light beam onto a recording surface of an optical information recording medium having at least two information recording layers and by receiving reflected light of the light beam is provided. The optical information reproduction apparatus includes an extraction section for extracting an envelope signal of a reproduction signal when the reproduction signal reproduced by focusing the light beam onto one information recording layer in the plural information recording layers has been modulated by interlayer crosstalk from another information recording layer; and a distortion correction section for correcting the distortion of the target reproduction signal caused by the interlayer crosstalk by gain-adjusting the reproduction signal containing DC components so that the envelope signal becomes constant.

Abstract: The focus is moved from a first layer (L0) to a second layer (L1) of a double-layered optical disk by stopping a control loop operation and applying acceleration pulses for an interlayer jump to a two-axis electromagnetic actuator. Here, switching timing between acceleration and deceleration for an interlayer jump is generated based on the rate of change of a SUM signal obtained from a light-sensitive element (27), the SUM signal is distinguished by a specific threshold TH, and an S-shaped error signal is distinguished by thresholds THH and THL with different positive/negative level, thereby performing a pull-in operation of focus control. In addition, at the time of the interlayer jump, a liquid crystal element (23) for correcting the spherical aberration is optimized in advance for the cover layer thickness of the target layer L1.

Abstract: An optimum performance is achieved relative to write-once type optical recording mediums on which information is recorded by means of a blue-violet semiconductor laser. An optical disc recording/reproduction apparatus 10 comprises an LD control section 17 adapted to control the irradiation power of a laser when writing data. If the cycle of the channel clock is T, when forming a recording mark having a length of n×T (n being an integer not smaller than 2), a pulse beam is irradiated onto the write-once type information recording medium for n/2 times (decimals, if any, being to be rounded down). When forming a recording mark having a length of not smaller than 6T and even number times of T, a pulse beam is irradiated for n/2 times with all the intermediate pulse beams synchronized with the phase of the channel clock except the leading pulse beam and the tail end pulse beam.