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Claims  |
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What is claimed is:
1. A light detection apparatus for an optical data storage system,
comprising
at least one re-imaging lens for re-imaging a light beam produced by a
light source and reflected from an optical storage medium to form an image
of a light spot formed by said light beam on said storage medium, said
light spot having a spatial distribution covering more than one domain of
information stored in said storage medium,
and at least one detector for detecting a selected portion of said image of
said light spot covering more than one domain of information,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
said light detection apparatus further comprising a blocking device for
allowing a selected portion of said light beam comprising said selected
portion of said image to pass toward said at least one detector, while
blocking an unselected portion of said light beam comprising an unselected
portion of said image, said unselected portion of said image containing at
least a portion of at least one domain of information.
2. A light detection apparatus in accordance with claim 1 wherein
said blocking device comprises a plate comprising a pinhole aperture, said
plate being located in an image plane of said re-imaging lens,
said re-imaging lens re-images onto said plate said light beam reflected
from said storage medium, in a manner such that
said light beam forms on said plate said image of said light spot formed by
said light beam on said storage medium,
said image on said plate is centered on said aperture,
a central portion of said light beam comprising a central portion of said
image passes through said aperture,
and a peripheral portion of said light beam comprising a peripheral portion
of said image is blocked by said plate,
and said at least one detector detects said portion of said light beam that
passes through said aperture.
3. A light detection apparatus in accordance with claim 2, wherein
said light detection further comprises a collimating lens for collimating
said portion of said light beam that passes through said aperture,
and said at least one detector detects said portion of said light beam that
passes through said aperture and said collimating lens.
4. A light detection apparatus in accordance with claim 2 wherein said
storage medium is a magneto-optical disk.
5. A light detection apparatus in accordance with claim 4 wherein
said magneto-optical disk contains domains that rotate an angle of
polarization of said light beam as said light beam reflects off of said
magneto-optical disk,
said light detection apparatus further comprises a polarization splitter
for splitting said portion of said light beam that passes through said
aperture into two parts each having an intensity proportional to a
respective component of polarization of said reflected light beam,
and there are two said detectors for respectively detecting said two parts
of said light beam.
6. A light detection apparatus in accordance with claim 2 wherein
said re-imaging lens has a focal length that is greater than a focal length
of an objective lens that focuses said light beam on said storage medium
and that collimates said light beam after reflection from said storage
medium,
and said image on said plate is a magnified image of said light spot on
said storage medium.
7. A light detection apparatus for an optical data storage system,
comprising
at least one re-imaging lens for re-imaging a light beam produced by a
light source and reflected from an optical storage medium to form an image
of a light spot formed by said light beam on said storage medium,
and at least one detector for detecting a selected portion of said image,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said light detection apparatus further comprises a blocking device
for allowing a selected portion of said light beam comprising said
selected portion of said image to pass toward said at least one detector,
while blocking an unselected portion of said light beam,
wherein said blocking device comprises a plate comprising a pinhole
aperture, said plate being located in an image plane of said re-imaging
lens,
wherein said re-imaging lens re-images onto said plate said light beam
reflected from said storage medium, in a manner such that
said light beam forms on said plate said image of said light spot formed by
said light beam on said storage medium,
said image on said plate is centered on said aperture,
a central portion of said light beam comprising a central portion of said
image passes through said aperture,
and a peripheral portion of said light beam comprising a peripheral portion
of said image is blocked by said plate,
wherein said at least one detector detects said portion of said light beam
that passes through said aperture,
wherein said central portion of said image corresponds to a central portion
of said light spot on said storage medium, said central portion of said
light spot covering a location on said storage medium at which a domain of
information is stored,
and wherein said peripheral portion of said image corresponds to a
peripheral portion of said light spot on said storage medium, said
peripheral portion of said light spot covering locations on said storage
medium at which domains of information other than said domain covered by
said central portion of said light spot are stored.
8. A light detection apparatus for an optical data storage system,
comprising
at least one re-imaging lens for re-imaging a light beam produced by a
light source and reflected from an optical storage medium to form an image
of a light spot formed by said light beam on said storage medium,
and at least one detector for detecting a selected portion of said image,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said at least one detector is a combination detector comprising a
plurality of rows of light-sensitive detection elements, and said at least
one re-imaging lens re-images said light beam reflected from said storage
medium in a manner such that said light beam forms on said at least one
detector said image of said light spot formed by said light beam on said
storage medium and said selected portion of said image covers said
light-sensitive detection elements,
wherein said light detection apparatus further comprises a processor for
processing outputs of said light-sensitive detection elements,
wherein said optical storage medium comprises a plurality of servo pads, a
pair of said servo pads being encoded in proximity to a center line of
each of a plurality of tracks of data on said optical storage medium,
wherein said processor produces first and second signals corresponding to
intensity of light reflected from first and second servo pads of said pair
of servo pads and detected by a detection element in a tracking row of
said combination detector, compares said first signal with said second
signal, and adjusts fine tracking of said light detection apparatus by an
amount proportional to a difference between said first and second signals
in a manner such that said tracking row of said light-sensitive detection
elements is aligned with a said track, and
wherein said at least one detector is constructed in a manner such that
each said row is aligned with a said track when said tracking row is
aligned with a said track.
9. A light detection apparatus in accordance with claim 8 wherein
said image on said combination detector comprises a plurality of image
portions covering a plurality of respective said light-sensitive detection
elements,
and each said image portion is an image of a portion of said light spot
formed by said light beam on said storage medium.
10. A light detection apparatus in accordance with claim 9 wherein said
storage medium is a magneto-optical disk.
11. A light detection apparatus in accordance with claim 10 wherein
said magneto-optical disk contains domains that rotate an angle of
polarization of said light beam as said light beam reflects off of said
magneto-optical disk,
said light detection apparatus further comprises a polarization splitter
for splitting said light beam reflected from said magneto-optical disk
into two parts each having an intensity proportional to a respective
component of polarization of said reflected light beam,
and there are two said combination detectors for respectively detecting
said two parts of said light beam.
12. A light detection apparatus in accordance with claim 11 wherein there
are two said re-imaging lenses that respectively re-image said two parts
of said light beam onto said two combination detectors.
13. A light detection apparatus in accordance with claim 11 wherein there
is one said re-imaging lens that re-images said reflected light beam onto
said polarization splitter.
14. A light detection apparatus in accordance with claim 8, wherein
said processor produces a plurality of differential signals, each said
differential signal corresponding to an output of a said light-sensitive
detection element in a first said detector minus an output of a
corresponding said light-sensitive detection element in a second said
detector,
and said processor analyzes said differential signals to detect domains of
information smaller than said light spot on said storage medium.
15. A light detection apparatus in accordance with claim 14 wherein said
processor is adapted to detect simultaneously domains of information
contained in a plurality of tracks on said magneto-optical disk.
16. A light detection apparatus in accordance with claim 15, wherein said
combination detector is arranged to detect simultaneously domains
contained in a plurality of distinct and respective tracks on said
magneto-optical disk.
17. A light detection apparatus in accordance with claim 8 wherein
said portion of said light spot on said storage medium, which corresponds
to said image portion covering said at least one light-sensitive detection
element, covers a location on said storage medium at which a domain of
information is stored.
18. A light detection apparatus for an optical data storage system,
comprising
at least one re-imaging lens for re-imaging a light beam produced by a
light source and reflected from an optical storage medium to form an image
of a light spot formed by said light beam on said storage medium, said
light spot having a spatial distribution covering more than one domain of
information stored in said storage medium,
and at least one detector for detecting a selected portion of said image of
said light spot covering more than one domain of information,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said at least one re-imaging lens has a focal length that is
greater than a focal length of an objective lens that focuses said light
beam on said storage medium and that collimates said light beam after
reflection from said storage medium,
and wherein said image is a magnified image of said light spot on said
storage medium.
19. A light detection apparatus for an optical data storage system,
comprising
at least one re-imaging lens for re-imaging a light beam produced by a
light source and reflected from an optical storage medium to form an image
of a light spot formed by said light beam on said storage medium,
and at least one detector for detecting a selected portion of said image,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said light detection apparatus further comprises said optical
storage medium, said optical storage medium comprises a magnetic layer for
storing said information and a refraction layer overlying said magnetic
layer, said refraction layer has an index of refraction such that the
wavelength of said light beam within said refraction layer is less than
the wavelength of said light beam in air, said information encoded on said
magnetic layer comprises domains smaller than a wavelength of said light
beam in air but not smaller than the wavelength of said light beam as said
light beam passes through said refraction layer, whereby said refraction
layer has an index of refraction high enough to enable said light
detection apparatus to resolve said domains.
20. An optical data storage media drive comprising
a light source for producing a light beam,
an objective lens for focusing said light beam on a storage medium, and for
collimating said light beam after reflection from said storage medium,
and a light detection apparatus comprising
at least one re-imaging lens for re-imaging said light beam collimated by
said objective lens to form an image of a light spot formed by said light
beam on said storage medium, said light spot having a spatial distribution
covering more than one domain of information stored in said storage
medium,
and at least one detector for detecting a selected portion of said image of
said light spot covering more than one domain of information, said
selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
said light detection apparatus further comprising a blocking device for
allowing a selected portion of said light beam comprising said selected
portion of said image to pass toward said at least one detector, while
blocking an unselected portion of said light beam comprising an unselected
portion of said image, said unselected portion of said image containing at
least a portion of at least one domain of information.
21. A storage media drive in accordance with claim 20 wherein
said blocking device comprises a plate comprising a pinhole aperture, said
plate being located in an image plane of said re-imaging lens,
said re-imaging lens re-images onto said plate said light beam collimated
by said objective lens, in a manner such that
said light beam forms an image on said plate that is an image of a light
spot formed by said light beam on said storage medium,
said image on said plate is centered on said aperture,
a central portion of said light beam comprising a central portion of said
image passes through said aperture,
and a peripheral portion of said light beam comprising a peripheral portion
of said image is blocked by said plate,
and said at least one detector detects said portion of said light beam that
passes through said aperture.
22. A storage media drive in accordance with claim 21, wherein
said light detection further comprising a collimating lens for collimating
said portion of said light beam that passes through said aperture,
and said at least one detector detects said portion of said light beam that
passes through said aperture and said collimating lens.
23. A storage media drive in accordance with claim 21 wherein said storage
medium is a magneto-optical disk.
24. A storage media drive in accordance with claim 23 wherein
said magneto-optical disk contains domains that rotate an angle of
polarization of said light beam as said light beam reflects off of said
magneto-optical disk,
said light detection apparatus further comprises a polarization splitter
for splitting said portion of said light beam that passes through said
aperture into two parts each having an intensity proportional to a
respective component of polarization of said reflected light beam,
and there are two said detectors for respectively detecting said two parts
of said light beam.
25. A storage media drive in accordance with claim 21 wherein
said re-imaging lens has a focal length that is greater than a focal length
of said objective lens that focuses said light beam on said storage medium
and that collimates said light beam after reflection from said storage
medium,
and said image on said combination detector is a magnified image of said
light spot on said storage medium.
26. An optical data storage media drive comprising
a light source for producing a light beam,
an objective lens for focusing said light beam on a storage medium, and for
collimating said light beam after reflection from said storage medium,
and a light detection apparatus comprising
at least one re-imaging lens for re-imaging said light beam collimated by
said objective lens to form an image of a light spot formed by said light
beam on said storage medium,
and at least one detector for detecting a selected portion of said image,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said light detection apparatus further comprises a blocking device
for allowing a selected portion of said light beam comprising said
selected portion of said image to pass toward said at least one detector,
while blocking an unselected portion of said light beam,
wherein said blocking device comprises a plate comprising a pinhole
aperture, said plate being located in an image plane of said re-imaging
lens,
wherein said re-imaging lens re-images onto said plate said light beam
collimated by said objective lens, in a manner such that
said light beam forms an image on said plate that is an image of a light
spot formed by said light beam on said storage medium,
said image on said plate is centered on said aperture,
a central portion of said light beam comprising a central portion of said
image passes through said aperture,
and a peripheral portion of said light beam comprising a peripheral portion
of said image is blocked by said plate,
wherein said at least one detector detects said portion of said light beam
that passes through said aperture,
wherein said central portion of said image corresponds to a central portion
of said light spot on said storage medium, said central portion of said
light spot covering a location on said storage medium at which a domain of
information is stored,
and wherein said peripheral portion of said image corresponds to a
peripheral portion of said light spot on said storage medium, said
peripheral portion of said light spot covering locations on said storage
medium at which domains of information other than said domain covered by
said central portion of said light spot are stored.
27. An optical data storage media drive comprising
a light source for producing a light beam,
an objective lens for focusing said light beam on a storage medium, and for
collimating said light beam after reflection from said storage medium,
and a light detection apparatus comprising
at least one re-imaging lens for re-imaging said light beam collimated by
said objective lens to form an image of a light spot formed by said light
beam on said storage medium,
and at least one detector for detecting a selected portion of said image,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said at least one detector is a combination detector comprising a
plurality of rows of light-sensitive detection elements, and said at least
one re-imaging lens re-images said light beam collimated by said objective
lens in a manner such that said light beam forms on said at least one
detector said image of said light spot formed by said light beam on said
storage medium and said selected portion of said image covers said
light-sensitive detection element,
said light detection apparatus further comprises a processor for processing
outputs of said light-sensitive detection element,
wherein said optical storage medium comprises a plurality of servo pads, a
pair of said servo pads being encoded in proximity to a center line of
each of a plurality of tracks of data on said optical storage medium,
wherein said processor produces first and second signals corresponding to
intensity of light reflected from first and second servo pads of a said
pair of servo pads and detected by a detection element in a tracking row
of said combination detector, compares said first signal with said second
signal, and adjusts fine tracking of said light detection apparatus by an
amount proportional to a difference between said first and second signals
in a manner such that said tracking row of said light-sensitive detection
elements is aligned with a said track, and
wherein said at least one detector is constructed in a manner such that
each said row is aligned with a said track when said tracking row is
aligned with a said track.
28. A storage media drive in accordance with claim 27 wherein
said combination detector is located in an image plane of said re-imaging
lens,
said image on said combination detector comprises a plurality of image
portions covering a plurality of respective said light-sensitive detection
elements,
and each said image portion is an image of a portion of said light spot
formed by said light beam on said storage medium.
29. A storage media drive in accordance with claim 28 wherein said storage
medium is a magneto-optical disk.
30. A storage media drive in accordance with claim 29 wherein
said magneto-optical disk contains domains that rotate an angle of
polarization of said light beam as said light beam reflects off of said
magneto-optical disk,
said light detection apparatus further comprises a polarization splitter
for splitting said light beam reflected from said magneto-optical disk
into two parts each having an intensity proportional to a respective
component of polarization of said reflected light beam,
and there are two said combination detectors for respectively detecting
said two parts of said light beam.
31. A storage media drive in accordance with claim 30 wherein there are two
said re-imaging lenses that respectively re-image said two parts of said
light beam onto said two combination detectors.
32. A storage media drive in accordance with claim 30 wherein there is one
said re-imaging lens that re-images said reflected light beam onto said
polarization splitter.
33. A storage media drive in accordance with claim 27, wherein
said processor produces a plurality of differential signals, each said
differential signal corresponding to an output of a said light-sensitive
detection element in a first said detector minus an output of a
corresponding said light-sensitive detection element in a second said
detector,
and said processor analyzes said differential signals to detect domains of
information smaller than said light spot on said storage medium.
34. A storage media drive in accordance with claim 33 wherein said
processor is adapted to detect simultaneously domains of information
contained in a plurality of tracks on said magneto-optical disk.
35. A storage media drive in accordance with claim 34, wherein said
combination detector is arranged to detect simultaneously domains
contained in a plurality of distinct and respective tracks on said
magneto-optical disk.
36. A storage media drive in accordance with claim 27 wherein
said portion of said light spot on said storage medium, which corresponds
to said image portion covering said at least one light-sensitive detection
element, covers a location on said storage medium at which a domain of
information is stored.
37. An optical data storage media drive comprising
a light source for producing a light beam,
an objective lens for focusing said light beam on a storage medium, and for
collimating said light beam after reflection from said storage medium,
and a light detection apparatus comprising
at least one re-imaging lens for re-imaging said light beam collimated by
said objective lens to form an image of a light spot formed by said light
beam on said storage medium, said light spot having a spatial distribution
covering more than one domain of information stored in said storage
medium,
and at least one detector for detecting a selected portion of said image of
said light spot covering more than one domain of information, said
selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said at least one re-imaging lens has a focal length that is
greater than a focal length of said objective lens that focuses said light
beam on said storage medium and that collimates said light beam after
reflection from said storage medium,
and wherein said image is a magnified image of said light spot on said
storage medium.
38. An optical data storage media drive comprising
a light source for producing a light beam,
an objective lens for focusing said light beam on a storage medium, and for
collimating said light beam after reflection from said storage medium,
and a light detection apparatus comprising
at least one re-imaging lens for re-imaging said light beam collimated by
said objective lens to form an image of a light spot formed by said light
beam on said storage medium,
and at least one detector for detecting a selected portion of said image,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said storage media drive further comprises said optical storage
medium, said optical storage medium comprises a magnetic layer for storing
said information and a refraction layer overlying said magnetic layer,
said refraction layer has an index of refraction such that the wavelength
of said light beam within said refraction layer is less than the
wavelength of said light beam in air, said information encoded on said
magnetic layer comprises domains smaller than a wavelength of said light
beam in air but not smaller than the wavelength of said light beam as said
light beam passes through said refraction layer, whereby said refraction
layer has an index of refraction high enough to enable said light
detection apparatus to resolve said domains.
39. A method of detecting a light beam reflected from storage media in an
optical data storage system, comprising the steps of
re-imaging a light beam produced by a light source and reflected from an
optical storage medium to form an image of a light spot formed by said
light beam on said storage medium, said light spot having a spatial
distribution covering more than one domain of information stored in said
storage medium,
and detecting a selected portion of said image of said light spot covering
more than one domain of information,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
said method further comprising the step of allowing a selected portion of
said light beam comprising said selected portion of said image to be
detected, while blocking an unselected portion of said light beam, said
unselected portion of said image containing at least a portion of at least
one domain of information.
40. A method in accordance with claim 39 wherein
said step of re-imaging said light beam reflected from said storage medium
comprises re-imaging said light beam onto a plate comprising a pinhole
aperture, in a manner such that
said light beam forms on said plate said image of said light spot formed by
said light beam on said storage medium,
said image on said plate is centered on said aperture,
a central portion of said light beam comprising a central portion of said
image passes through said aperture,
and a peripheral portion of said light beam comprising a peripheral portion
of said image is blocked by said plate,
and said step of detecting said selected portion of said image comprises
detecting said portion of said light beam that passes through said
aperture.
41. A method in accordance with claim 40 wherein
said method further comprises the step of collimating said portion of said
light beam that passes through said aperture,
and said step of detecting said selected portion of said image comprises
detecting said collimated portion of said light beam.
42. A method in accordance with claim 41 wherein said storage medium is a
magneto-optical disk.
43. A method in accordance with claim 42 wherein
said magneto-optical disk contains domains that rotate an angle of
polarization of said light beam as said light beam reflects off of said
magneto-optical disk,
said method further comprises the step of splitting said portion of said
light beam that passes through said aperture into two parts each having an
intensity proportional to a respective component of polarization of said
reflected light beam,
and said step of detecting said collimated portion of said light beam that
passes through said aperture comprises detecting said two parts of said
light beam.
44. A method in accordance with claim 40 wherein said image on said plate
is a magnified image of said light spot on said storage medium.
45. A method of detecting a light beam produced by a light source and
reflected from storage media in an optical data storage system, comprising
the steps of
re-imaging a light beam reflected from an optical storage medium to form an
image of a light spot formed by said light beam on said storage medium,
and detecting a selected portion of said image,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
said method further comprising the step of allowing a selected portion of
said light beam comprising said selected portion of said image to be
detected, while blocking an unselected portion of said light beam,
wherein said step of re-imaging said light beam reflected from said storage
medium comprises re-imaging said light beam onto a plate comprising a
pinhole aperture, in a manner such that
said light beam forms on said plate said image of said light spot formed by
said light beam on said storage medium,
said image on said plate is centered on said aperture,
a central portion of said light beam comprising a central portion of said
image passes through said aperture,
and a peripheral portion of said light beam comprising a peripheral portion
of said image is blocked by said plate,
wherein said step of detecting said selected portion of said image
comprises detecting said portion of said light beam that passes through
said aperture,
wherein said central portion of said image corresponds to a central portion
of said light spot on said storage medium, said central portion of said
light spot covering a location on said storage medium at which a domain of
information is stored,
and wherein said peripheral portion of said image corresponds to a
peripheral portion of said light spot on said storage medium, said
peripheral portion of said light spot covering locations on said storage
medium at which domains of information other than said domain covered by
said central portion of said light spot are stored.
46. A method of detecting a light beam reflected from storage media in an
optical data storage system, comprising the steps of
re-imaging a light beam produced by a light source and reflected from an
optical storage medium to form an image of a light spot formed by said
light beam on said storage medium,
and detecting a selected portion of said image,
said selected portion of said image containing only such information as is
encoded on a region of said optical data storage medium that is
illuminated by a corresponding portion of said light spot,
wherein said step of re-imaging said light beam reflected from said storage
medium comprises re-imaging said light beam onto at least one combination
detector comprising a plurality of rows of light-sensitive detection
elements, in a manner such that said light beam forms on said at least one
detector said image of said light spot formed by said light beam on said
storage medium and said selected portion of said image covers said
light-sensitive detection elements, and said step of detecting said
selected portion of said image comprises detecting said selected portion
of said image by means of said light-sensitive detection elements,
wherein said optical storage medium comprises a plurality of servo pads, a
pair of said servo pads being encoded in proximity to a center line of
each of a plurality of tracks of data on said optical storage medium,
wherein said method further comprises the steps of:
producing first and second signals corresponding to intensity of light
reflected from first and second servo pads of a | | |
