Storage Technology Corporation Partners Ii

Alexander M Muckle

Harlan P Mathews

Paul M Romano

Brad R Reddersen

Albin Kenneth Johnson

Karl J Stahl

An optical disk servo system includes a coarse access and tracking system for optical head control and a fine access and tracking system for read/write beam control. Enlarged servo tracks are pre-recorded on the optical disk between bands of data track locations. The coarse system illuminates a relatively large area of the disk surface encompassing at least one of the servo tracks and detects light from the enlarged illuminated area. Suitable means including a photo-detector array identifies and controls the optical head position by means of the light returned from the illuminated servo track. Such photo-detection means are insensitive to light reflected from the data tracks. The fine access and tracking system uses a conventional, three spot tracking and read system, two spots for data track following and one spot for data track reading. The fine access and tracking system controls a galvanometer mirror or other suitable means steering the read spot beams. Data writing is accomplished by fine tracking a previously recorded data track and maintaining the write beam a constant distance therefrom.

Fine and coarse servo system for access and tracking on an optical disk

A system and method for optically measuring and maintaining track pitch in an optical storage system. A set of at least four calibration tracks, each having a prescribed track pitch or distance therebetween, are precisely placed on a recording medium of the optical storage system during the manufacture thereof. When this recording medium is subsequently inserted into the optical storage system, the track pitch of a select pair of the calibration tracks is optically measured by maximizing the amplitude of a data read radiation beam, and an offset signal is generated in response to this measurement. This offset signal is used within the optical storage system for controllably positioning a second radiation beam with respect to a first radiation beam, the first radiation beam being directed to follow a previously written data track on the recording medium. The offset signal may be stored so that it need only be generated during an initialization or calibration mode of the optical storage system, and thereafter be readily available for positioning the second radiation beam relative to the first radiation beam. The select pair of calibration tracks may be an inner pair, having additional tracks adjacent both sides thereof, or an outer pair, having an additional track adjacent only one side thereof; thereby having included in the offset signal the optical effects of having additional data tracks adjacent or not adjacent the respective sides of the pair of calibration tracks whose track pitch is being measured.

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Boulder County, CO, United States of America

Alexander M Muckle