Abstract: When using an optical disc medium that includes pit trains having their widths narrower than a diffraction limit, it is difficult to detect a tracking error signal and take a tracking-servo control while increasing pit density in a direction orthogonal to a pit-train extension direction. Information pit trains are arranged spirally or concentrically and formed in a structure in which their depths are changed periodically at a pitch radially along the optical disc medium, so that the tracking error signal can be obtained by push-pull detection of diffraction light from the structure.

Abstract: Provided is a signal processing device including: an adaptive filter; a PRML circuit for sequentially generating binarized data from a filtered reproduced waveform by sampling at sampling points in a period based on a clock signal and sequentially generating a partial response waveform which is to be the target waveform from the binarized data; a calculating unit for sequentially calculating first phase errors from a difference between the target waveform and the filtered reproduced waveform; a limiting unit for outputting second phase errors by excluding a specific phase error from the first phase errors; and a clock generating unit for generating the clock signal of a frequency corresponding to the second phase errors; wherein the specific phase error includes a phase error at a time when the partial response waveform reaches a specific level which excludes at least a level not less than a predetermined amplitude level.

Abstract: An optical disc device uses an optical disc (6) capable of super-resolution reproduction, and includes a semiconductor laser (1), a laser driving circuit (21) that supplies a driving current to the semiconductor laser, a light receiving element (8) that detects return light from the optical disc (6) and obtains reproduction signal of recording data of the optical disc (6), and a light emission amount control means (22) that controls a light emission amount of the semiconductor laser (1) by the laser driving circuit (21) so as to keep a peak intensity of a focused light spot formed on an information recording layer of the optical disc 6 to be greater than or equal to a peak intensity at which a super-resolution effect is obtained.

Abstract: An optical information recording medium includes at least one recording layer, a protective layer that transmits a focused laser beam, and a super-resolution functional layer that changes an optical characteristic in a local region smaller than the diffraction limit determined by the optical performance of the focusing optical system and the wavelength of the laser beam during at least the period of irradiation by the focused laser beam. The maximum thickness (K) between the light incidence surface of the protective layer and the recording layer is 0.083 mm.

Abstract: An optical head device mounted in an optical disc device. The optical head device is provided with a diffractive optical element and a photodetector. The diffractive optical element has: a primary diffraction region at a location on which the positive and negative first-order components and some of the zero-order component of a reflectively diffracted light beam are incident; and secondary diffraction regions at locations on which the rest of the zero-order component but none of the positive or negative first-order components of the reflectively diffracted light beam are incident. A main light-receiving section of the photodetector receives the zero-order component of a transmissively diffracted light beam that has passed through the primary diffraction region and the secondary diffraction regions.

Abstract: An optical information recording medium includes at least one recording layer, a protective layer that transmits a focused laser beam, and a super-resolution functional layer that changes an optical characteristic in a local region smaller than the diffraction limit determined by the optical performance of the focusing optical system and the wavelength of the laser beam during at least the period of irradiation by the focused laser beam. The maximum thickness (K) between the light incidence surface of the protective layer and the recording layer is 0.083 mm.

Abstract: An optical pickup device includes a first optical system and a second optical system. The first optical system and the second optical system each include a mirror member that reflects light from a light source to change a direction of propagation of the light to a direction substantially perpendicular to the information storage surface of an optical disc. The first optical system and the second optical system are arranged such that a direction in which light from a first light source enters a first mirror member is substantially perpendicular to a direction in which light from a second light source enters a second mirror member.

Abstract: A first signal is detected from the central part of a light beam returning from a super-resolution optical disc; a second signal is detected from a peripheral part in a direction corresponding to a track on the super-resolution optical disc; a gain adjustment unit is provided to adjust the amplitude of the first signal; a subtraction unit is provided to generate a third signal by subtracting, from the second signal, the first signal with the amplitude adjusted by the gain adjustment unit; and an unit is provided to generate a reproduced signal by combining the first signal and a signal obtained by delaying the third signal.

Abstract: [Object] A recoding playback apparatus and an optical disk are provided that allows reduction of a low frequency noise at a time of playback of a super resolution optical disk including small record marks whose size is below the diffractive limitation, to enhance quality of a playback signal. [Means for Solution] The reflective beams from the optical disk are received by dividing into outer portion beams and a center portion beam, and a playback signal is created by combining such beams based on respective different gains. Based on received amounts of light or amounts of low frequency noise in respective light receiving regions, adjustment or determination of gain values is made, or the optical head apparatus is optically adjusted, whereby the low frequency noise is optimally suppressed. Further, a specific region is provided on the optical disk for making the foregoing adjustment.

Abstract: An optical head device mounted in an optical disc device. The optical head device is provided with a diffractive optical element and a photodetector. The diffractive optical element has: a primary diffraction region at a location on which the positive and negative first-order components and some of the zero-order component of a reflectively diffracted light beam are incident; and secondary diffraction regions at locations on which the rest of the zero-order component but none of the positive or negative first-order components of the reflectively diffracted light beam are incident. A main light-receiving section of the photodetector receives the zero-order component of a transmissively diffracted light beam that has passed through the primary diffraction region and the secondary diffraction regions.

Abstract: An optical pickup with a simplified structure in which, according to the type of optical disc, diffracted light from three types of laser light can be directed efficiently onto a photodetector and appropriate focus control can be performed based on the signals detected by the photodetector, and a diffractive optical element that can be used in the optical pickup, which has a semiconductor laser 10 that can emit three types of laser light, a diffractive optical element 42 that diffracts the laser light reflected from the optical disc 31, and a single photodetector 43 that detects the diffracted light exiting the diffractive optical element 42.

Abstract: A recording and reproducing device that is capable of improving its reproduction quality by efficiently detecting a reproduction signal having small low frequency noises even when reproducing data on a super-resolution optical disk including recording marks smaller than a diffraction limit.

Abstract: A first signal is detected from the central part of a light beam returning from a super-resolution optical disc; a second signal is detected from a peripheral part in a direction corresponding to a track on the super-resolution optical disc; a gain adjustment unit is provided to adjust the amplitude of the first signal; a subtraction unit is provided to generate a third signal by subtracting, from the second signal, the first signal with the amplitude adjusted by the gain adjustment unit; and an unit is provided to generate a reproduced signal by combining the first signal and a signal obtained by delaying the third signal.

Abstract: An object of the present invention is to provide an extraction optical system capable of separating and extracting a signal light and a stray light with a simple configuration, and an optical head device including the same. A phase plate and a phase plate are +?/4 phase plates, while a phase plate and a phase plate are ??/4 phase plates. A focal line, a focal line and a focal line represent a focal line of a stray light, a focal line of a reproduction light and a focal line of a stray light, respectively. All beams of the reproduction light enter the state in which a polarization direction is rotated by 90 degrees after passing through the phase element. In contrast to the all light bundles of the reproduction light, polarization directions of all light bundles of the stray lights and are not rotated even after passing through the phase element.

Abstract: Problem: To provide a recording and reproducing device that is capable of improving in its reproduction quality by efficiently detecting a reproduction signal having small low frequency noises even when reproducing data on a super-resolution optical disk including recording marks smaller than a diffraction limit. Means for Solving the Problem: By using an aperture control means that makes an exit pupil diameter of an objective lens that is provided across a beam return path to make an effect on the reflection light from the optical disk, larger than an exit pupil diameter of the lens provided across a beam return path, peripheral portion's light of the reflection light with a low frequency noise rate is efficiently received and detected without a high-NA objective lens requiring a lot of manufacturing costs, so that a reproduction signal is obtained in good quality.

Abstract: [Object] A recoding playback apparatus and an optical disk are provided that allows reduction of a low frequency noise at a time of playback of a super resolution optical disk including small record marks whose size is below the diffractive limitation, to enhance quality of a playback signal. [Means for Solution] The reflective beams from the optical disk are received by dividing into outer portion beams and a center portion beam, and a playback signal is created by combining such beams based on respective different gains. Based on received amounts of light or amounts of low frequency noise in respective light receiving regions, adjustment or determination of gain values is made, or the optical head apparatus is optically adjusted, whereby the low frequency noise is optimally suppressed. Further, a specific region is provided on the optical disk for making the foregoing adjustment.

Abstract: A signal, which is derived from the relationship between the lens shift amount of an objective lens and the amount of the positional-deviation, of a received light beam with respect to a light-receiving plane, which occurs in the tangential direction on a photodetector, is corrected by an offset caused by asymmetry in the intensity distribution of reflected light; a multiplication value is obtained by multiplying the corrected signal by a predetermined constant; based on a focus error signal obtained by subtracting the calculated value from the calculation expression according to the conventional astigmatism method, the focusing servo control is performed.

Abstract: An optical pickup device includes a first optical system and a second optical system. The first optical system and the second optical system each include a mirror member that reflects light from a light source to change a direction of propagation of the light to a direction substantially perpendicular to the information storage surface of an optical disc. The first optical system and the second optical system are arranged such that a direction in which light from a first light source enters a first mirror member is substantially perpendicular to a direction in which light from a second light source enters a second mirror member.

Abstract: An object of the present invention is to provide an extraction optical system capable of separating and extracting a signal light and a stray light with a simple configuration, and an optical head device including the same. A phase plate and a phase plate are +?/4 phase plates, while a phase plate and a phase plate are ??/4 phase plates. A focal line, a focal line and a focal line represent a focal line of a stray light, a focal line of a reproduction light and a focal line of a stray light, respectively. All beams of the reproduction light enter the state in which a polarization direction is rotated by 90 degrees after passing through the phase element. In contrast to the all light bundles of the reproduction light, polarization directions of all light bundles of the stray lights and are not rotated even after passing through the phase element.

Abstract: An optical-pickup-adjustment optical disk used for adjusting or producing an optical pickup device, includes a transparent protective substrate; and an optical-pickup-adjustment middle-depth information recording layer formed on a side of an inside surface of the transparent protective substrate, wherein the optical-pickup-adjustment middle-depth information recording layer is formed to have a middle depth which is a center of the maximum depth of the maximum-depth information recording layer prescribed by the optical disk standard and the minimum depth of the minimum-depth information recording layer prescribed by the optical disk standard.