Storage Technology Corporation Partners Ii

Paul M Romano

Harlan P Mathews

James W Baer

Robert P McIntosh

James W Hargarten

David W Rickert

Alexander M Muckle

Charles M Reilly

Jerry Walker

Henry H Hoshiko

A beam alignment system and method for aligning a first radiation beam with respect to a second radiation beam as these beams share a desired optical path. Beam steering means, such as a galvonometer controlled mirror, steer the alignment of the first beam as it enters the shared optical path. Detection means are employed to sense the relative alignment between the first and second beams as they travel through the shared path. This sensed alignment is compared to a desired alignment, and a position error signal is generated to indicate the error therebetween. The position error signal, in turn, is used to steer the galvonometer controlled mirror in order to force the beam alignment error between the two beams to zero. In a preferred embodiment, the beam alignment system is used in an optical disk storage system to precisely position a write beam a desired distance from a read beam; thereby allowing a data track written with the write beam on a storage disk to be spaced a desired distance (the track pitch) from a previously written track that is being followed by the read beam.

Beam alignment system

A system and method for maintaining a prescribed track pitch in an optical storage system wherein a second radiation beam is aligned a desired distance from a first radiation beam, the first radiation beam being controllably steered to follow a previously written data track on a record carrier used within the optical storage system. A write alignment servo aligns the second radiation beam the prescribed distance from the first radiation beam in response to an offset signal. The offset signal is generated by optically measuring the distance between a pair of calibration tracks that have previously been placed on the disk so as to have the desired track pitch therebetween. The effect of variations or drift occurring in the optical or electrical components of either the write alignment servo or the optical track pitch measurement system is significantly reduced by regularly calibrating against the fixed track pitch of the calibration tracks.

Track pitch calibration system for use in optical storage devices

A beam alignment signal processing system wherein a true beam position error signal is generated regardless of beam intensity. This beam position error signal is used within a beam alignment system that maintains a desired alignment between first and second beams traveling in parallel along a desired optical path. A detector senses the position of the beams as the beams (or portions of the beams) are directed onto a surface thereof. The detector generates a set of position signals that indicate the position at which a beam, or at which an energy centroid associated with a plurality of beams, falls upon the detector surface. A first set of position signals is generated corresponding to the position of the first beam on the detector surface with the second beam turned off. These signals are stored in signal storage means. The second beam is turned back on, and a second set of position signals is generated corresponding to the position of the centroid of the first and second beams on the detector surface. A third set of position signals is then generated from the first and second set of position signals corresponding to the position of the second beam on the detector surface. The position error signal is finally generated from the first and third sets of position signals. Detector offset correction means are employed to remove the effects of detector offset from the sets of position signals. Normalization means are likewise employed to remove the effects of beam intensity variations from the sets of position signals.

Beam alignment signal processing

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

Paul M Romano