Medium position sensing
View Patent ↗A method of determining coordinates for a storage medium includes: determining diffraction data from a plurality of diffraction patterns corresponding to diffractive markers of the medium; and combining the diffraction data to determine composite coordinates for the medium. The composite coordinates may include three translational coordinates and three rotational coordinates. The act of determining diffraction data may include shining a plurality of beams on a selection of the diffractive markers, and measuring the corresponding diffraction patterns in one or more photodetectors to determine the diffraction data. In this latter case the photodetectors may be segmented. The act of combining the diffraction data to determine composite coordinates may include solving a matrix system that couples the diffraction data and the composite coordinates. Each diffractive marker may include a pit. The storage medium may include a holographic storage medium.
1. A method of encoding position for a storage medium, comprising:
adding a plurality of diffractive markers to the medium for making locations of stored data; and
adding a plurality of compound grooves between diffractive markers along a coordinate direction, each compound groove having a transverse groove type for encoding position across multiple compound grooves.
2. A method as claimed in claim 1 , wherein each diffractive marker includes a pit and each compound groove includes a plurality of pits.
3. A method as claimed in claim 1 , wherein the act of adding the plurality of diffractive markers includes etching the diffractive markers, and the act of adding the plurality of compound grooves includes etching the compound grooves.
4. A method as claimed in claim 1 , wherein the storage medium includes a holographic medium and the stored data includes holographic data.
5. A method as claimed in claim 1 , wherein position is encoded in a frame invariant manner with LSFR (Linear Feedback Shift Register) code.
6. A method as claimed in claim 1 , wherein position is encoded with a cyclic frame invariant code.
7. A method of encoding position for a storage medium, comprising:
adding a plurality of diffractive markers to the medium for marking locations of stored data; and
adding a plurality of compound grooves between diffractive markers along a coordinate direction, each compound groove having internal interruptions for encoding position within that compound groove.
8. A method as claimed in claim 7 , wherein each diffractive marker includes a pit and each compound groove includes a plurality of pits.
9. A method as claimed in claim 7 , wherein the act of adding the plurality of diffractive markers includes etching the diffractive markers, and the act of adding the plurality of compound grooves includes etching the compound grooves.
10. A method as claimed in claim 7 , wherein the storage medium includes a holographic medium and the stored data includes holographic data.
11. A method as claimed in claim 7 , wherein position is encoded in a frame invariant manner with an LFSR code.
12. A method as claimed in claim 7 , wherein position is encoded with a cyclic frame invariant code.
13. A method of encoding position for a storage medium, comprising:
adding a plurality of diffractive markers to the medium for marking locations of stored data, the diffractive markers being arranged along a first coordinate direction and along a second coordinate direction;
adding a plurality of first compound grooves between diffractive markers along the first coordinate direction, each first compound groove having a transverse groove type for encoding position across multiple first compound grooves, and each first compound groove having internal interruptions for encoding position within that first compound groove; and
adding a plurality of second compound grooves between diffractive markers along the second coordinate direction, each second compound groove having a transverse groove type for encoding position across multiple second compound grooves, and each second compound groove having internal interruptions for encoding position within that second compound groove.
14. A method as claimed in claim 13 , wherein each diffractive marker includes a pit and each compound groove includes a plurality of pits.
15. A method as claimed in claim 13 , wherein the act of adding the plurality of diffractive markers includes etching the diffractive markers, and the act of adding the plurality of compound grooves includes etching the compound grooves.
16. A method as claimed in claim 13 , wherein the storage medium includes a holographic medium and the stored data includes holographic data.
17. A method of determining position on a storage medium, comprising:
scanning the medium in a transverse direction across a plurality of compound grooves that are aligned in a coordinate direction of the medium, each compound groove having a transverse groove type for encoding position across multiple compound grooves, wherein crossing a threshold number of compound grooves determines a position on the medium.
18. A method as claimed in claim 17 , wherein the act of scanning includes:
shining a beam across the compound grooves;
measuring corresponding diffraction patterns in segmented photodetectors to determine the diffraction data; and
using the diffraction data to determine the position on the medium.
19. A method as claimed in claim 17 , wherein the storage medium includes a holographic medium.
20. A method of determining position on a storage medium, comprising:
scanning the medium along a compound groove that is aligned in a coordinate direction of the medium, the compound groove having internal interruptions for encoding position within the compound groove, wherein crossing a codeword of interruptions determines a position on the medium.
21. A method as claimed in claim 20 , wherein the act of scanning includes:
shining a beam along the compound groove;
measuring corresponding diffraction patterns in one or more photodetectors to determine the diffraction data; and
using the diffraction data to determine the position on the medium.
22. A method as claimed in claim 21 , wherein the photodetectors are segmented.
23. A method as claimed in claim 20 , wherein the storage medium includes a holographic medium.
24. A data storage system comprising:
a storage medium for storing data at different locations in the medium, the medium including a plurality of diffractive markers for marking locations of stored data in the medium and a plurality of compound grooves for marking positions on the medium, each compound groove having a transverse groove type for encoding position across multiple compound grooves.
25. A system as claimed in claim 24 , wherein scanning across a threshold number of compound grooves determines a position on the medium.
26. A system as claimed in claim 24 , wherein each diffractive marker includes a pit and each compound groove includes a plurality of pits.
27. A system as claimed in claim 24 , wherein the storage medium includes a holographic medium and the stored data includes holographic data.
28. A system as claimed in claim 27 , wherein a constellation of diffractive markers indicates a location of a hologram.
29. A system as claimed in claim 27 , wherein a constellation of four diffractive markers indicates a location of a hologram.
30. A system as claimed in claim 24 , wherein position is encoded in a frame invariant manner with an LFSR code.
31. A system as claimed in claim 24 , wherein position is encoded with a cyclic frame invariant code.
32. A data storage system comprising:
a storage medium for storing data at different locations in the medium, the medium including a plurality of diffractive markers for marking locations of stored data in the medium and a plurality of compound grooves for marking positions on the medium, each compound groove having internal interruptions for encoding position within the compound groove.
33. A system as claimed in claim 32 , wherein scanning across a codeword of interruptions determines a position on the medium.
34. A system as claimed in claim 32 , wherein each diffractive marker includes a pit and each compound groove includes a plurality of pits.
35. A system as claimed in claim 32 , wherein the storage medium includes a holographic medium and the stored data includes holographic data.
36. A system as claimed in claim 35 , wherein a constellation of diffractive markers indicates a location of a hologram.
37. A system as claimed in claim 35 , wherein a constellation of four diffractive markers indicates a location of a hologram.
38. A system as claimed in claim 32 , wherein position is encoded in a frame invariant manner with an LFSR code.
39. A system as claimed in claim 32 , wherein position is encoded with a cyclic frame invariant code.