Sharp Kabushiki Kaisha Corporation

Yoshikazu Fujii

Toshihisa Deguchi

Kenji Ohta

Tetsuya Inui

Shigemi Maeda

Tetuya Inui

Hideyoshi Yamaoka

Akira Takahashi

Hiroyuki Katayama

Yoshiteru Murakami

Tohru Okuda

Schohichi Katoh

An optical memory element includes a guide track groove portion and address signal pit portion for indicating the address of the guide track groove. The address signal pit portion has a pit width narrower than the groove width of the guide track groove portion.

Optical memory apparatus

Magneto-optical memory element

A method is provided for manufacturing a magneto-optical memory element having guide grooves for storing information. The method includes applying a laser beam onto a resist film material located on a substrate to produce guide track grooves and address signal pits. Thereafter the resist film is developed. The remaining resist film is removed and a magnetic medium layer is deposited on the substrate.

Method for manufacturing a magneto-optical memory element

An optical memory device comprising a substrate and guide tracks having a depth of .lambda./8n or less formed on said substrate, wherein .lambda. is the wavelength of laser light used for the optical memory device, and n is the refraction index of the guide track portion of the substrate.

Optical memory device having guide tracks shaped for increasing the

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.

Optical head in an optical memory device

An optical memory element comprises a substrate, a recording medium layer and an aluminum silicon nitride film laminated in this order.

Optical memory element

A magneto-optical memory device includes a recording medium having a magnetic anisotropy in a direction perpendicular to the main surface thereof. A semiconductor laser is employed in an optical system of the magneto-optical memory device for reproduction purposes. A polarization beam splitter is disposed in the optical system. A multi coated dielectric thin-film is deposited on the reflection surface of the polarization beam splitter in order to establish a desired relationship between the reflection of the P-polarization component and the S-polarization component.

Optical system in a magneto-optical memory device

A light beam position controlling apparatus includes a linear motor for driving an optical head in the radial direction of an optical disk, a radial actuator built-in within said optical head and adapted to drive an objective lens for causing the light beam to be accurately positioned in the radial direction of the optical disk and to rotate a mirror for causing the light beam to be deflected in the radial direction of the optical disk, which can be improved in the compression factor of the servo performance, by providing a phase lag compensation circuit and a damping correction circuit for increasing the gain of the transfer function at the resonance frequency of both the linear motor and radial actuator.

Tight beam position controlling apparatus

Disclosed below is a control device for positioning an optical focus in an optical disc apparatus that records, plays back, and erases any information by irradiating optical beams such as the laser beams onto a recording media composed of magnetic film, wherein the control device is characterized in that; it incorporates a focussing permanent magnet that makes up a closed magnetic circuit, a focussing yoke plate, a focussing yoke, and a focussing device coil installed so that it crosses a focussing magnetic space existing that exists between the focussing yoke plate and the focussing yoke so that the focussing magnetic space can be created in an area close to the recording media which is installed in the closed magnetic circuit. In addition, the optical focus position control device that executes both the tracking and focussing control operations for the optical disc apparatus also includes mechanism that drives the objective lens in the direction of dual axes, i.e., in the vertical (up/down) and horizontal (left/right) directions.

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Nara, Japan

Yoshikazu Fujii