04598393 is referenced by 47 patents and cites 11 patents.

A servo tracking system for an optical record uses a pattern of preformed optically detectable uniform servo track marks disposed in parallel spaced apart columns in combination with a beam from a radiation source split by a diffraction grating into three beams having unequal power distribution. The placement of the beams across the pattern of preformed servo tracks on an optical recording material has one position for writing data by the center beam on an information track while the two outside beams intercept track marks on two adjacent tracks. For reading recorded data tracks, the beams shift to a second position in which the center beam intercepts marks on a servo track while the two outside beams read two adjacent data tracks. Because of the unequal power distribution, increasing the energy level of the radiation source causes the intensity of the middle beam during recording to reach a level sufficient to record while the two outside tracking beams remain below that threshold. The track marks in adjacent columns may be in an offset position with regard to track marks of the adjoining column, to provide self-clocking during recording.

Title
Three-beam optical servo tracking system with two-track parallel readout
Application Number
6/597485
Publication Number
4598393
Application Date
April 6, 1984
Publication Date
July 1, 1986
Inventor
Warren J Vinzant
Menlo Park
CA, US
Norman A Peppers
Belmont
CA, US
James L Buxton
East Palo Alto
CA, US
Gerald A Pierce
Redwood City
CA, US
Assignee
Drexler Technology Corporation
CA, US
IPC
G11B 7/125
G11B 7/013
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