Rca Inc.

George J Ammon

Charles W Reno

Stephen L Corsover

A wideband optical disc data record/playback apparatus is provided. The apparatus includes means for splitting the output of a single laser into multiple beams. The record beams are independently modulated and used to simultaneously record data at extremely high rates on the surface of an optical disc. The apparatus is capable of recording 1.times.10.sup.11 bits of data on one surface of an optical disc at data rates of 100 to 300 Mb/s. In addition, a plurality of coplanar low power beams are used for playback and data verification purposes. In the playback mode a single beam is split into a plurality of low power beams and one of the plurality of beams is dithered such that the dithered beam exhibits periodic excursions in a radial direction across the surface of the disc. The dithered beam is used for tracking purposes in both the playback and record mode. In a preferred embodiment the playback beams are split by an optical grating and dithered by an acousto-optic device.

Multi-beam optical record and playback apparatus having an improved beam

An apparatus is provided for randomly accessing data in a data retrieval system which utilizes a disc-shaped record medium. Information is stored in a plurality of tracks on the surface of the record medium. When the readout transducer is to be moved from its present read position (e.g., track #1,000) to a new read position (e.g., track #2,000), the difference in the number of tracks in the new position and the present position is loaded into a counter. As the transducer is moved across the disc surface the number of track crossings is counted and compared to the number loaded into counter. Even though the read head is moving outward, for example, eccentricities in the tracks will cause the head to 'see' both 'in' and 'out' crossings, the number of actual tracks crossed will be equal to the number of 'out' crossings minus the number of 'in' crossings. When the number of track crossings is equal to the number in the counter, the transducer will be enabled to follow the desired track.

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Medford, NJ, United States of America

George J Ammon