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US 5,396,478 AGranted
Optical data storage system with aberration compensation for reduced servo crosstalk
AssigneeInternational Business Machines Corporation
InventorMatthias C. Krantz
Life of this patent
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Abstract
An optical data storage system comprises a laser for generating a beam of light, an optical data storage media, transmission optics for directing the beam of light to the optical medium, reception optics for receiving a reflected beam from the medium, and circuits for generating a data, tracking error and focus error signals. The reception optics includes a segmented detector. The signals from at least two of these segments are differentially adjusted such that the resulting output focus error signal is approximately independent of nonfocus wavefront aberrations.
Claims32
An optical data storage system comprising:
- a radiation means for producing a first radiation beam;
- an optical data storage medium having data tracks;
- a radiation transmission means for transmitting the first radiation beam from the radiation source to a first spot on a data track of the medium;
- a radiation reception means for receiving a second radiation beam from the first spot on the medium, the radiation reception means including a segmented optical detector, the detector being segmented into a plurality of first stripe sections and non-first stripe sections, the first stripe sections having a longitudinal dimension substantially perpendicular to a direction in which the beam at the detector is displaced when the beam at the storage medium moves off of the data track;
- and
- an output signal generator for generating an output signal connected to the segmented optical detector, the signals from the first stripe sections differentially adjusted relative to the signals from the non-first stripe sections, such that the resulting output signal is substantially independent of the wavefront aberrations in the second radiation beam.
3 more elements
An optical data storage system comprising:
- a light source for producing a first light beam;
- a means for receiving an optical data storage medium having data tracks;
- an adjustable focussing means for focussing the first light beam to a first spot on a data track of the medium;
- a movement means for moving the first light beam across the optical medium;
- an optical reception means for receiving a second light beam from the medium, the optical reception means including a segmented optical detector, the detector being segmented into a plurality of first stripe sections and non-first stripe sections, the first stripe sections having a longitudinal dimension substantially perpendicular to a direction in which the beam at the detector is displaced when the beam at the storage medium moves off of the data track
- a tracking error signal means connected to the optical detector for generating a tracking error signal;
- and
- a focus error signal means connected to the optical detector for generating a focus error signal, the focus error signal means including means for differentially amplifying the output signals from the first strip sections relative to the output signals from the non-first stripe sections such that the focus error signal is substantially independent of changes in the tracking error signal.
5 more elements
An optical data storage system comprising:
- a light source for producing a first light beam;
- a means for receiving an optical data storage medium having data tracks;
- an adjustable focussing means for focussing a first light beam to a first spot on a data track of the medium;
- a movement means for moving the first light beam across the optical medium;
- an optical reception means for receiving a second light beam from the medium, the optical reception means including a segmented optical detector having a segmented optical filter, the optical filter being segmented into a plurality of first stripe sections and non-first stripe section, the first stripe sections having a longitudinal dimension substantially perpendicular to a direction in which the beam at the detector is displaced when the beam at the storage medium moves off of the data track, the optical filter for differentially adjusting the amount of light passing through the first stripe sections relative to the non-first stripe sections;
- a tracking error signal means connected to the optical detector for generating a tracking error signal;
- and
- a focus error signal means connected to the optical detector for generating a focus error signal, the focus error signal being substantially independent of changes in the tracking error signal.
5 more elements
A method for an optical data storage system comprising the steps of:
- generating a first radiation beam;
- directing the first radiation beam to a first spot on a data track of an optical data storage medium;
- receiving a reflected radiation beam from the optical data storage medium at a segmented radiation detector, the detector being segmented into a plurality of first stripe sections and non-first stripe sections, the first stripe sections having a longitudinal dimension substantially perpendicular to a direction in which the beam at the detector is displaced when the beam at the storage medium moves off of the data track;
- processing the signals from each of the segments of the radiation detector to produce an output signal;
- and
- differentially amplifying the signals from the first stripe sections relative to the signals from the non-first stripe sections such that the resulting output signals are approximately independent of wavefront aberrations in the reflected radiation beam.
3 more elements
A method for an optical data storage system comprising the steps of:
- generating a first radiation beam;
- directing the first radiation beam to a first spot on a data track of an optical data storage medium;
- passing a reflected radiation beam through an optical filter, the optical filter being segmented into a plurality of first stripe filter sections and non-first stripe filter sections, the first stripe filter sections having a longitudinal dimension substantially perpendicular to a direction in which the beam at the detector is displaced when the beam at the storage medium moves off of the data track, the optical filter for differentially adjusting the amount of light passing through the first stripe sections relative to the non-first stripe sections;
- receiving the reflected radiation beam at a segmented radiation detector;
- and
- processing the signals from each of the segments of the radiation detector to produce an output signal.
3 more elements
An optical data storage system comprising:
- a light source for producing a first light beam;
- a means for receiving an optical data storage medium having data tracks;
- an adjustable focussing means for focussing the first light beam to a first spot on a data track of the medium;
- a movement means for moving the first light beam relative to the medium;
- an optical reception means for receiving a second light beam from the medium, the optical reception means including a segmented optical detector, the segments being divided by a plurality of boundary lines, a first pair of boundary lines dividing the detector in a first direction, thereby forming a right zone of segments, a first middle zone of segments, and a left zone of segments, a second and third pair of boundary lines dividing the detector in a second direction substantially perpendicular to the first direction, thereby forming an upper zone of segments, an upper stripe zone of segments, a second middle zone of segments, a lower stripe zone of segments, and a lower zone of segments;
- a tracking error signal means connected to the optical detector for generating a tracking error signal;
- and
- a focus error signal means connected to the optical detector for generating a focus error signal, the focus error signal means including an amplifier for amplifying the signals from the upper stripe and lower stripe zones relative to the upper, second middle and lower zones, and including means connected to the amplifier for comparing the sum of the signals from the left and fight zones with the sum of the signals from the first middle zone.
5 more elements
An optical data storage system comprising:
- a light source for producing a first light beam:
- a means for receiving an optical data storage medium having data tracks;
- an adjustable focussing means for focussing the first light beam to a first spot on a data track of the medium;
- a movement means for moving the first light beam relative to the medium;
- an optical reception means for receiving a second light beam from the medium, the optical reception means including a segmented optical detector and an optical filter overlying the detector, the segments of the detector being divided by a plurality of boundary lines, a first pair of boundary lines dividing the detector in a first direction, thereby forming a right zone of segments, a first middle zone of segments, and a left zone of segments, a second and third pair of boundary lines dividing the detector in a second direction substantially perpendicular to the first direction, thereby forming an upper zone of segments, an upper stripe zone of segments, a second middle zone of segments, a lower stripe zone of segments and a lower zone of segments, the optical filter having a first filter zone overlying the upper, second middle and lower zones of the detector and having a second filter zone overlying the upper stripe and lower stripe zones of the detector, the second filter zone allowing more light to pass than the first filter zone;
- a tracking error signal means connected to the optical detector for generating a tracking error signal;
- a focus error signal means connected to the optical detector for generating a focus error signal, a focus error signal means including a means for comparing the sum of the signals from the left and right zones with the sum of the signals from the first middle zone.
4 more elements
An optical data storage system comprising:
- a light source for producing a first light beam;
- a means for receiving an optical data storage medium having data tracks;
- an adjustable focussing means for focussing the first light beam to a first spot on a data track of the medium;
- a movement means for moving the first light beam relative to the medium;
- an optical reception means for receiving a second light beam from the medium, the optical reception means including a segmented optical detector and an optical filter overlying the optical detector, the segments of the optical detector being divided by plurality of boundary lines, a first pair of boundary lines dividing the detector in a first direction, thereby forming a right zone of segments, a detector middle zone of segments and a left zone of segments, the optical filter having a first and second pair of filter boundary lines dividing the filter in a second direction substantially perpendicular to the first direction, thereby forming an upper filter zone, an upper stripe filter zone, a middle filter zone, a lower stripe filter zone, and a lower filter zone, the upper stripe filter and lower stripe filter zones allowing more light to pass than the upper, middle and lower filter zones;
- a tracking error signal means connected to the optical detector for generating a tracking error signal;
- and
- a focus error signal means connected to the optical detector for generating a focus error signal, the focus error signal means including means for comparing the sum of the signals from the left and right zones of the detector with the sum of the signals from the middle detector zone of the detector.
5 more elements
Dependencies are inferred from the claim text.