International Business Machines Corporation

Timothy S Gardner

Ronald P Stahl

Delbert A Hansen

Brian Gerald Goodman

Alan A Fennema

Milton Russell Latta

Edward M Engler

Tomoaki Kimura

Morovat B Tayefeh

Yoshihiro Hirasaka

David P McReynolds

Anthony G Dewey

Syed T Shafaat

Paul H Francois

Hideaki Iwasaki

Stephen M Ward

A magnetooptical disk recording device has a far-field detector for detecting radial position of a laser beam with respect to tracks on the disk. The far-field detector has a reference line dividing first and second photo detectors. The reference line is centered radially with respect to center lines of the tracks. The reference line is also center lengthwise to be tangentially center with respect to a tangential point on the track. The detector is adjustable both radially and tangentially. The tangential adjustment is based upon sensing two low reflective calibration marks on the disk that indicate centering the laser beam, hence the track tangent point, on the reference line. The calibration is based upon obtaining minimum noise in the detector output signal that signifies that the laser beam is centered on the length of the detector reference line. The calibration marks are in a mirror area disposed at one radial extremity of the disk. The marks are radially elongate and disposed in a radially outward diverge with respect to each other. The marks are disposed at 45 degrees with respect to two circumferentially spaced apart radial lines of the disk.

Calibrating an optical detector to minimize noise from undesired

Optical disk with marks used for calibrating an optical detector to

A coarse position sensor is provided for an optical recording device to generate a substantially linear coarse position signal, indicative of the position of a coarse carriage along the range of its travel, and which also is substantially immune to environmental and device variations. The sensor includes a light source mounted to a drive frame at one end of the range of travel, a position sensitive device fixed to the frame at the opposite end of the range of travel and facing the light source, and a deflecting optical element mounted to the coarse carriage in the path of the light. As the coarse carriage travels along its stroke between the inner and outer diameters of the optical disk, the amount of deflection of the light beam on the position sensitive device from a reference location will change. Based upon a trigonometric equation, a coarse position signal generator receives the output of the position sensitive device and generates a substantially linear coarse position signal indicative of the position of the coarse carriage.

Coarse position sensor, and method for locating same, in an optical disk

This invention provides an equal path length lateral shearing interferometer and its implementation in focus detection devices, particularly for optical data storage devices. The interferometer comprises a beamsplitter and two abutting roof prisms. Shifting the placement of a roof prism along an axis orthogonal to the direction of light propagation and to the peak of the roof creates a lateral shear between the two output beams. Rotation a roof prism about this axis produces a tilt between the two output beams. This creates an interference pattern with a rotational orientation which is a function of the focus of the beam impinging on the optical storage medium. A pattern sensor is provided to adjust the focus of the beam in an accurate and dynamic manner.

Focus error detection using an equal path length lateral shearing

An optical drive provides an internal routine for automatically optimizing the common mode rejection ratio of the magneto-optic data output signal. A microprocessor provides control to a controller module which in turn supplies a plurality of calibration signals to a data detecting portion. The calibration signals modify predetermined parameters of the data detecting portion based upon measuring a predetermined parameter indicative of the common mode rejection ratio. The common mode rejection ratio optimization corrects for mismatches in both the optical elements and in the electronic data circuits.

Common mode rejection control in an optical disk drive

A relative position error signal is calibrated in an optical storage device in which a tracking error signal (TES) varies as the light beam shifts its position through the objective lens. The calibration is performed by moving the coarse carriage to a predetermined region of the optical disk and measuring the TES. The fine actuator is adjusted until the tracking error signal equals a predetermined value. Then, the relative position error signal is read and an adjustment to the RPE gain is calculated to bring the gain to a predetermined value. The adjusted gain is used during normal disk access operations.

Relative position sensing calibration for optical storage device

An optoelectronic system for controlling laser drive current to produce a power level at the target independent of changes in the transmissivity of a beamsplitter positioned in the optical path between the laser source and the target. A second beamsplitter with transmissivity and reflectivity factors matched to the first beamsplitter is used to direct portions of light to two photodetectors. The two photodetectors are connected to circuits which produce a signal proportional to the power transmitted by the first beamsplitter divided by the power reflected by the second beamsplitter, that quotient multiplied by the sum of the photodetector signals to produce a final detection signal which is used as input to the servo control of laser drive current.

Laser power control independent of beamsplitter transmissivity

The invention is a cleaning cartridge which includes a housing and a tube for injecting a compressed gas therethrough and into specific areas of an optical disk drive. The tube is removably connectable at one end to a compressed gas supply, and is aimed at the other end to direct gas exiting therefrom at both the objective lens, beam-directing prism or mirror, or other internal optical disk drive components when the cartridge is seated in the drive. Upon insertion of the cleaning cartridge into the optical disk drive in the usual manner for any optical disk cartridge, gas is released from the compressed gas source, through the tube, and into the optical disk drive. The use of such a cleaning cartridge provides for easy, effective cleaning of any internal optical disk drive component without the abrasion and potential inconveniences associated with mechanical brushing, wiping, or other techniques.

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Tucson, AZ, United States of America

Timothy S Gardner