Micro-positioning movement of holographic data storage system components
View Patent ↗According to one aspect, a holographic storage system including micro-actuators is presented. In one example of one aspect of the invention, the device includes a spatial light modulator, a detector, a storage medium, and at least one micro-actuator configured to move at least one of the spatial light modulator, the detector, and the storage medium. The micro-actuators may include a servomechanism or the like to control the positioning of a component based on feedback associated with a misalignment of a detected image. According to another aspect of the invention, various methods for determining component misalignments of a holographic storage system are presented.
1. A method for operating a holographic storage system comprising:
detecting an image;
determining a misalignment of the detected image; and
activating at least one micro-actuator configured to position at least one component of the system based at least in part on the misalignment, the at least one component of the system comprising a member of the group consisting of: a detector, a storage medium, and a spatial light modulator device.
2. The method of claim 1 , wherein the misalignment is characterized by at least one of translation, rotation, tilt, or magnification of the detected image relative to the detector.
3. The method of claim 1 , wherein a servomechanism controls the at least one micro-actuator based on a feedback signal.
4. The method of claim 1 , wherein the at least one component includes a detector.
5. The method of claim 1 , wherein the at least one component includes a storage medium.
6. The method of claim 1 , wherein the at least one component includes a spatial light modulator.
7. The method of claim 1 , wherein the at least one component includes an optical element.
8. The method of claim 1 , wherein determining the misalignment further includes the acts of measuring a channel metric associated with the image.
9. The method of claim 8 , wherein the channel metric includes a measurement of at least one of average intensity, signal-to-noise ratio, page bit error rate, number of decoder iterations, and equalizer filter coefficients.
10. The method of claim 1 , wherein determining the misalignment further includes the acts of measuring a page metric associated with the image.
11. The method of claim 10 , wherein the page metric includes at least one of alignment holograms, page codes, registration marks, pixel cross-hairs, or pixel cross-correlation.
12. The method of claim 1 , wherein the medium is encoded with alignment information.
13. The method of claim 1 , wherein the medium is encoded with at least one of a locator block, a crosshair, and a reserved block.
14. The method of claim 1 , wherein determining the misalignment further includes the acts of measuring pixel cross-correlation of at least a portion of the image with a reference image.
15. The method of claim 14 , wherein the pixel cross-correlation produces a correlation peak associated with the misalignment.
16. The method of claim 15 , wherein determining the misalignment further includes the acts of interpolating between values of the correlation peak.
17. The method of claim 16 , wherein the act of interpolating includes an estimated point spread function of the system.
18. The method of claim 16 , wherein the act of interpolating includes a polynomial function.
19. The method of claim 14 , wherein a D.C. component of the detected image and the reference image are removed.
20. The method of claim 14 , wherein a multiple of partial detected images and reference images are evaluated independently to determine misalignments of local regions of the image.
21. The method of claim 20 , wherein the misalignments of local regions are used to determine at least one of image rotation and image magnification.
22. The method of claim 1 , wherein determining the misalignment of the detected image includes determining the magnitude and direction of the offset.
23. The method of claim 1 , wherein determining the misalignment of the detected image includes determining the magnitude of the offset.
24. The method of claim 23 , further including the acts of:
adjusting the relative position of at least one component;
determining a second misalignment of a detected image; and
making a second adjustment based on the second misalignment.
25. A method for operating a holographic storage system, comprising the acts of:
providing a detector array and a storage medium;
detecting an image stored in the storage medium with the detector array;
determining a misalignment of the detected image with the detector array; and
activating at least one micro-actuator for adjusting a component of the system based on the misalignment, the at least one component of the system comprising a member of the group consisting of: a detector, a storage medium, and a spatial light modulator device.
26. The method of claim 25 , wherein the misalignment is characterized by at least one of translation, rotation, tilt, or magnification of the detected image.
27. The method of claim 25 , further including the acts of providing a spatial light modulator, wherein the spatial light modulator encodes an object beam.
28. The method of claim 26 , wherein adjusting the position of the component includes adjusting the spatial light modulator.
29. The method of claim 25 , wherein the act of adjusting includes adjusting at least one of the detector and the storage medium.
30. The method of claim 29 , wherein the act of adjusting a position of the component includes the acts of activating at least one micro-actuator configured to act on the component.
31. The method of claim 30 , wherein the at least one micro-actuator includes a piezoelectric crystal.
32. The method of claim 25 , wherein determining the misalignment further includes the acts of measuring a channel metric associated with the image.
33. The method of claim 32 , wherein the channel metric includes a measurement of at least one of average intensity, signal-to-noise ratio, page bit error rate, number of decoder iterations, and equalizer filter coefficients.
34. The method of claim 25 , wherein determining the misalignment further includes the acts of measuring a page metric associated with the image.
35. The method of claim 34 , wherein the page metric includes at least one of alignment holograms, page codes, registration marks, pixel cross-hairs, or pixel cross-correlation.
36. The method of claim 25 , wherein the image includes an alignment hologram.
37. The method of claim 25 , wherein the image includes a page code.
38. The method of claim 37 , wherein the page code indicates an address of the image.
39. The method of claim 37 , wherein the page code is used to calibrate a servo system.
40. The method of claim 25 , wherein the image includes at least one registration mark.
41. The method of claim 25 , wherein the image includes a cross-hair mark.
42. The method of claim 25 , wherein determining the misalignment further includes the acts of measuring pixel cross-correlation of at least a portion of the image with a reference image.
43. The method of claim 42 , wherein the pixel cross-correlation produces a correlation peak indicating the misalignment.
44. The method of claim 43 , wherein determining the misalignment further includes the acts of interpolating between values of the correlation peak.
45. The method of claim 44 , wherein the act of interpolating includes an estimated point spread function of the system.
46. The method of claim 44 , wherein the act of interpolating includes a polynomial function.
47. The method of claim 42 , wherein a D.C. component of the detected image and the reference image are removed.
48. The method of claim 42 , wherein a multiple of partial detected images and reference images are evaluated independently to determine misalignments of local regions of the image.
49. The method of claim 48 , wherein the misalignments of local regions are used to determine at least one of image rotation and image magnification.
50. The method of claim 25 , wherein determining the misalignment of the detected image includes determining the magnitude and direction of the offset.
51. The method of claim 25 , wherein determining the misalignment of the detected image includes determining the magnitude of the offset.
52. The method of claim 51 , further including the acts of:
adjusting the relative position of at least one component;
determining a second misalignment of a detected image; and
making a second adjustment based on the second misalignment.
53. A method for operating a holographic storage system comprising:
detecting an image;
determining a misalignment of the detected image by measuring pixel cross-correlation of at least a portion of the image with a reference image and determining a correlation peak associated with the misalignment; and
activating at least one micro-actuator configured to position at least one component of the system based at least in part on the misalignment.
54. The method of claim 53 , wherein the misalignment is characterized by at least one of translation, rotation, tilt, or magnification of the detected image relative to the detector.
55. The method of claim 53 , wherein a servomechanism controls the at least one micro-actuator based on a feedback signal.
56. The method of claim 53 , wherein the at least one component is a detector.
57. The method of claim 53 , wherein the at least one component includes a storage medium.
58. The method of claim 53 , wherein the at least one component includes a spatial light modulator.
59. The method of claim 53 , wherein determining the misalignment further includes the acts of measuring a page metric associated with the image.
60. The method of claim 59 , wherein the page metric includes at least one of alignment holograms, page codes, registration marks, pixel cross-hairs, or pixel cross-correlation.
61. The method of claim 53 , wherein the medium is encoded with alignment information.
62. The method of claim 53 , wherein determining the misalignment further includes the acts of interpolating between values of the correlation peak.
63. The method of claim 62 , wherein the act of interpolating includes an estimated point spread function of the system.
64. The method of claim 62 , wherein the act of interpolating includes a polynomial function.
65. The method of claim 53 , wherein a multiple of partial detected images and reference images are evaluated independently to determine misalignments of local regions of the image.
66. The method of claim 65 , wherein the misalignments of local regions are used to determine at least one of image rotation and image magnification.
67. A method for operating a holographic storage system, comprising:
detecting an image;
determining a misalignment of the detected image; and
activating at least one micro-actuator for positioning a detector or spatial light modulator device based at least in part on the misalignment.
68. The method of claim 67 , wherein a servomechanism controls the at least one micro-actuator based on a feedback signal.
69. The method of claim 67 , wherein the at least one micro-actuator positions the detector.
70. The method of claim 67 , wherein the at least one micro-actuator positions the storage medium.
71. The method of claim 67 , wherein determining the misalignment further includes the acts of measuring a channel metric associated with the image.
72. The method of claim 67 , wherein determining the misalignment further includes the acts of measuring a page metric associated with the detected image.
73. The method of claim 67 , wherein the medium is encoded with alignment information.
74. The method of claim 67 , wherein the medium is encoded with at least one of a locator block, a crosshair, and a reserved block.
75. The method of claim 67 , wherein determining the misalignment further includes the acts of measuring pixel cross-correlation of at least a portion of the image with a reference image.
76. The method of claim 75 , wherein the pixel cross-correlation produces a correlation peak associated with the misalignment.
77. The method of claim 76 , wherein determining the misalignment further includes the acts of interpolating between values of the correlation peak.
78. The method of claim 67 , wherein a multiple of partial detected images and reference images are evaluated independently to determine misalignments of local regions of the image.
79. The method of claim 78 , wherein the misalignments of local regions are used to determine at least one of image rotation and image magnification.