Abstract: An aberration detection device of the present invention is such that an absolute value of detection sensitivity of an aberration error signal is increased, and variation in detection sensitivity of the aberration error signal is little even when displacement between the center of light beam dividing means and the center of a bundle of light beams occurs due to a shift of a condensing optical system at the time of tracking control. A hologram element (2) divides light beams reflected from an information storage medium into at least two positive first order diffracted light beams. The hologram element (2) has a line (D1) extending in a radial direction and passing through an optical axis (OZ) and a division line (D2) having segments at least both ends thereof and a bulge in a center thereof, wherein the segments are substantially parallel to the line (D1), and the bulge (44) bulges toward the periphery of the hologram element (2) so that a top (D5) of the bulge (44) is substantially parallel to the line (D1).

Abstract: In a recordable optical disc apparatus, the efficiency of the work necessary for optimizing the write pulse condition (write strategy) is improved and the read compatibility among drive units is ensured by a minimum addition of circuitry. An edge shift amount or a read signal and a binarized result are stored in an external memory as digital data and are later processed by analysis software in a host PC. The write pulse shape and power conditions can be optimized to individual optical disc media in a short time by means of a simple circuit. Further, by optimizing the write pulse shape and power condition in view of the PRML class or the difference in NA of the head, any deterioration of read compatibility can be avoided.

Abstract: A kind of an optical disc is discriminated by a disc discriminating section, an order of aberrations to be corrected is set by an order setting section by the kind of the optical disc, drive of a liquid crystal optical element is controlled by a drive control section through a liquid crystal driver, and an aberration of an optical beam is corrected based on the order of the aberration. The level of importance of the aberration correction differs by the kind of the optical disc, and the order of the aberration is set by the level of importance of the aberration correction.

Abstract: An apparatus for and a method of detecting a wobble signal in accordance with a time shift includes comparing a basic wobble signal with reference levels to detect pulses representing the time shift in an analog fashion, and digitally determining a code value for the basic wobble signal on the basis of the widths of the pulses using a channel clock signal and a wobble clock signal. The determined code value is accumulated and serves as a basis on which final wobble data is produced.

Abstract: An automatic gain controller includes a voltage control gain amplifier amplifying input signals in response to a control voltage and producing output signals. A level detector detects peak and bottom levels of the output signals of the voltage control gain amplifier, and an analog-digital converter (ADC) converts the detected peak and bottom levels into digital signals. A peak detector detects a digital peak in response to a difference between the digital peak level and digital bottom level, and a voltage controller compares the digital peak and a reference voltage, and controls the control voltage.

Abstract: A heat-assisted magnetic recording head and a recording apparatus including the same are provided. The heat-assisted magnetic recording head includes a recording portion which produces magnetic field for recording information to a magnetic recording medium, and a waveguide which transmits light therethrough disposed to be adjacent to the recording portion and which emits the light toward the magnetic recording medium, wherein the waveguide comprises a light incident surface; a tapered portion having progressively narrower sections along the transmission direction of the light incident on the light incident surface and entering the waveguide; and a light-emitting surface which emits the light after the light is transmitted through the tapered portion.

Abstract: A servo control signal generation device for discriminating a kind of an optical disk, changing over between top and bottom envelope signals of an RF signal, and generating a defect signal and a mirror signal includes an RF generator for generating the RF signal from reflected light of an optical disk, a disk discriminator for discriminating a kind of the optical disk from the RF signal, and a top envelope generator and a bottom envelope generator respectively for generating the top and bottom envelope signals of the RF signal. If the disk has reflectance after recording which is lower than that before recording, the defect and mirror signals are generated respectively from the top and bottom envelope signals. If the disk has reflectance after recording which is higher than that before recording, the defect and mirror signals are generated respectively from the bottom and top envelope signals.

Abstract: An optical disc drive apparatus includes: a laser beam source; a collector device disposed as facing a disc that can record a signal, which collects a laser beam emitted from the laser beam source onto the disc; a record processing module which records the signal on the disc through the collector device while modulating laser power of the laser beam source; a reflecting light level detecting module which receives the reflecting light when the signal is recorded and detects a level of the reflecting light; a laser power control module which controls the laser power when the signal is recorded based on the detected level of the reflecting light; a tilt control module which controls a tilt angle between the disc and the collector device based on the detected level of the reflecting light; and a switching module which switches between control of the laser power and the tilt angle.

Abstract: A method for determining recording laser power on a super-resolution optical recording medium, on which information is recorded on a super-resolution optical recording medium by irradiating a laser beam modulated into a recording pulse train according to recording data to thereby form a recording mark train including recording marks and spaces smaller than the resolution limit of a reproduction optical system and recording marks and spaces equal to or larger than the resolution limit, is provided. At the time of recording, the method determines a minimum value and a maximum value of recordable laser powers determined by test-writing before recording, and determines a maximum value of a recordable range of laser power by adding to the minimum value one-third of a difference between the maximum value of the recordable laser powers and the minimum value. The method determines an optimal range of recording laser power from the minimum value of recordable laser powers to the maximum value of the recordable range.

Abstract: An apparatus comprises a moveable arm for positioning an optical transducer adjacent to a storage medium, a stationary light source, and a moveable mirror mounted at a pivot axis of the arm for reflecting light from the light source to the optical transducer. An actuator can be provided for rotating the moveable mirror through an angle of about one half of an angle of rotation of the moveable arm.

Abstract: An optical disc apparatus, as a learning operation before a recording or reproducing operation, rotates an optical disc at a first speed to read PID information, discriminates between lands and grooves of the optical disc, detects switching positions between lands and grooves, sets a rotation angle position of tracking pull-in of an objective lens of a time length that allows the PID information to be stably read, with respect to the switching position, and stores the set position information of tracking pull-in as learning result information. During recording or reproducing, the optical disc apparatus rotates the optical disk at a second speed higher than the first speed, pulls in the objective lens for tracking based on the stored position information of tracking pull-in, reads PID information, and performs the recording or reproducing operation while discriminating between lands and grooves and detecting switching positions between lands and grooves.

Abstract: In order to help maximize the capacity of an optical storage device, and increase the efficiency of addressing, a unique addressing scheme is utilized to provide addressing for an optical storage disk. Importantly, this scheme is compatible with multilayer disks and helps to minimize the potential for errors. In the addressing scheme of the present invention, the storage media is provided with a wobbled groove, which includes addressing information for the media. More specifically, the surface of the media is divided into predetermined sections, or portions, each portion having a selected number of wobble periods. Within these wobble periods, the amplitude of one single wobble period is either reduced or eliminated. The location of this reduced or eliminated wobble signal can then be determined by the readout system of the present invention and utilized to provide addressing information.

Abstract: An address is reliably demodulated when a phase shift in a wobble signal has been induced by a crosstalk signal from an adjacent track. Address information is modulated by a binary phase modulation scheme and embedded into an optical disk as a wobble signal. A 0-degree phase wobble signal and a 180-degree phase wobble signal are brought out of phase with each other by crosstalk from an adjacent track. An address decoder performs exclusive-OR operation of the wobble signal and a reference clock signal, to thus compute a ratio at which an exclusive-OR result assumes a value of 1 (H) every half period of the reference clock signal. The thus-computed ratio is compared with a threshold ratio. The threshold ratio is usually set to 50%. However, when a phase shift has been caused by crosstalk, a system controller changes the threshold ratio to a ratio of 50% or less.

Abstract: In a method and apparatus for generating optimum write power, a control unit controls a write voltage generating unit to generate sequentially write voltages of different levels to drive an optical read/write head to generate different write powers so as to write data on a plurality of write intervals of an optical recording medium in sequence. Simultaneously, a detecting and computing circuit detects a peak value, a first level and a second level of a write reflected signal generated by each write interval for computation so as to obtain a first control parameter of each write interval, and detects a peak value, a bottom value and a direct current level of a read reflected signal generated during reading of each write interval for computation so as to obtain a second control parameter of each write interval, thereby generating an optimum write power based on optimal first and second control parameters.