International Business Machines Corporation

Syed T Shafaat

Raymond Yardy

Edwin Ralph Childers

Dale Huber Anderson

Timothy S Gardner

David P McReynolds

Ronald P Stahl

Thomas J Schmitt

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 adaptor cartridge for holding a 90 mm optical disk cartridge for insertion into a 130 mm disk drive apparatus. The cartridge adaptor emulates the external dimensions and features of a 130 mm cartridge so that it can be loaded into and manipulated by the 130 mm drive in the same manner as a normal 130 mm cartridge. The cartridge adaptor contains a shutter arm for opening the 90 mm cartridge door upon insertion of the cartridge into the adaptor cartridge in much the same manner as a 90 mm cartridge door is opened when the cartridge is inserted into a 90 mm drive. The cartridge adaptor also contains a pseudo 90 mm spindle located in an adaptor hub. The pseudo spindle fits within the centering hole of the 90 mm media disk. The adaptor cartridge carries an annular magnet for attracting and holding the 90 mm media disk on the adaptor hub. The underside of the adaptor hub is a simulated 130 mm cartridge hub for mating with the 130 mm drive spindle. The adaptor cartridge may also include a rotating permanent magnet directly above the 90 mm cartridge shutter opening for providing a bias magnetic field to enable writing a magneto-optic disk. Proper orientation of the rotating magnet is provided by the 130 mm drive bias coil.

Cartridge adaptor

A recording/playback apparatus in which movable datum pins are held in a base casting. Upon insertion of a cartridge into a holding tray, within the apparatus, the pins are released to move into datum holes in the cartridge when the holes are positioned directly above the pins. The cartridge is then lowered onto the drive spindle and positioned on surfaces of the base casting. During the load cycle, the cartridge is allowed to move relative to the holding tray while continuing to be held in place relative to the base casting by the datum pins.

System for locating and holding a cartridge

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Langley, WA, United States of America

Syed T Shafaat