Mitsubishi Electric Corporation

Masayuki Omaki

Kenya Nakai

Nobuo Takeshita

Hironori Nakahara

Masahisa Shinoda

A light detection device includes a diffraction element and a light detection element. The diffraction element diffracts a beam of light that is incident on the diffraction element. The light detection element includes light receivers to receive diffracted light. The diffraction element generates beams of the diffracted light by dividing the beam of light. The light detection element determines a displacement of the beam of light relative to the diffraction element on the basis of quantities of light of the beams of the diffracted light. The light detection element determines an angle change of the beam of light relative to the diffraction element by dividing the quantity of light of one of the beams of the diffracted light.

Light detection device

An optical information recording medium has: a recording layer; a super-resolution functional layer; and a protective layer. Letting n be the refractive index of the protective layer with respect to a laser beam focused by a focusing optical system, &#x3bb;, be the wavelength of the laser beam, and dbe the depth of recording marks, when the super-resolution functional layer is irradiated by the focused laser beam, it forms a focused light spot including central light that irradiates the recording marks and peripheral light that irradiates a region outside the central light. The optical information recording medium further satisfies either the condition that the central light has a positive phase difference with respect to the peripheral light and d&#x3e;&#x3bb;/4n, or the condition that the central light has a negative phase difference with respect to the peripheral light and d&#x3c;&#x3bb;/4n.

Optical information recording medium and recording/reproducing device

An optical head device () provided with: an optical element () for transmissively diffracting a light beam emitted from a semiconductor laser (), generating a zero-order diffracted light beam and &#xb1;1-order diffracted light beams; and a photodetector () for receiving the zero-order diffracted light beam and the +1-order diffracted light beam after reflection from an optical disc (). The photodetector () includes a primary light receiving section () for receiving the zero-order diffracted light beam, and a first secondary light receiving section () disposed outward from the primary light receiving section (). The first secondary light receiving section () is positioned to detect an outer portion of the received light spot of the +1-order diffracted light beam, performs photoelectric conversion of this portion, and outputs a secondary detected signal.

Optical head device and optical disc device

An optical disc device uses an optical disc () capable of super-resolution reproduction, and includes a semiconductor laser (), a laser driving circuit () that supplies a driving current to the semiconductor laser, a light receiving element () that detects return light from the optical disc () and obtains reproduction signal of recording data of the optical disc (), and a light emission amount control means () that controls a light emission amount of the semiconductor laser () by the laser driving circuit () so as to keep a peak intensity of a focused light spot formed on an information recording layer of the optical discto be greater than or equal to a peak intensity at which a super-resolution effect is obtained. The light emission amount control means () controls a light emission amount of the semiconductor laser () by the laser driving circuit () based on a decrease rate D of a peak intensity of a focused light spot on an information recording layer of the optical disc () determined by an assumed disc tilt and a comatic aberration according to a thickness of a light transmitting layer of the optical disc (), and a lower limit value Pld_L of a light emission amount at which a predetermined reproduction performance is obtained.

Optical disc device, optical disc and testing method of optical disc

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.

Signal processing device, signal processing method, and optical disc apparatus

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.

Optical information recording medium and drive device

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. Secondary light-receiving sections receive the positive first-order component and/or the negative first-order component of the transmissively diffracted light beam that has passed through the secondary diffraction regions.

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Tokyo, Japan

Masayuki Omaki