Polytopic multiplex holography

• US 7,167,286 B2
• Filed: 06/23/2006
• Issued: 01/23/2007
• Est. Priority Date: 03/10/2003
• Status: Expired due to Fees

• Current Assignee: Akonia Holographics, LLC (Apple Inc.)
• Original Assignee: InPhase Technologies Incorporated (hVault, Inc.)
• Inventors: Anderson, Kenneth E., Curtis, Kevin R.
• Primary Examiner(s): Boutsikaris, Leonidas
• Application Number:
  US11/473,119
• Publication Number:
  US 20060238841A1
• Time in Patent Office: 214 Days
• Field of Search: 359/22, 359/24, 359/25, 359/35, 365/125, 365/216, 365/234, 369/103
• US Class Current: 359/25
• CPC Class Codes: G03H 1/0248 Volume holograms
• CPC Class Codes: G03H 1/202 Contact copy when the reconstruction beam for the master H1 also serves as reference beam for the copy H2
• CPC Class Codes: G03H 1/2645 Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing
• CPC Class Codes: G03H 1/265 Angle multiplexing; Multichannel holograms G03H1/268 takes precedence
• CPC Class Codes: G03H 2001/2207 Spatial filter, e.g. for suppressing higher diffraction orders
• CPC Class Codes: G03H 2001/2255 Holobject out of Fourier or hologram planes
• CPC Class Codes: G03H 2223/21 Anamorphic optical element, e.g. cylindrical astigmatic beam G03H2222/55
• CPC Class Codes: G03H 2223/54 Filtering the holobject information
• CPC Class Codes: G03H 2223/55 Arranged at a Fourier plane
• CPC Class Codes: G11B 7/0065 Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/00772 on record carriers storing information in the form of optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/083 relative to record carriers storing information in the form of optical interference patterns, e.g. holograms

Abstract

Disclosed is a multiplexing method and apparatus that allows holograms to be spatially multiplexed with partial spatial overlap between neighboring stacks of holograms. Each individual stack can additionally take full advantage of an alternate multiplexing scheme such as angle, wavelength, phase code, peristrophic, or fractal multiplexing, for example. An amount equal to the beam waist of the signal beam writing a hologram separates individual stacks of holograms. Upon reconstruction, a hologram and its neighbors will all be readout simultaneously. An filter is placed at the beam waist of the reconstructed data such that the neighbors that are read out are not transmitted to the camera plane. Alternatively, these unwanted reconstructions can be filtered out with an angular filter at an intermediate plane in the optical system that has a limited angular passband.

Claims

1. A method for holographic recording comprising:

creating a first hologram in a holographic media using a first reference beam and a first signal beam comprising page-wise data, modulated by a spatial light modulator (SLM), the first signal beam having a beam waist;

creating a second hologram using a second reference beam and a second signal beam, the second signal beam having a beam waist;

overlapping at least a portion of the second hologram with the first hologram; and

separating the first hologram from the second hologram such that substantially no portion of the beam waist of the first signal beam occurs at the same location as any portion of beam waist of the second signal beam, wherein the SLM is an amplitude modulating SLM, a phase modulating SLM or combinations thereof.

29. The method of claim 1 including:

multiplexing a first plurality of holograms with the first hologram at a first multiplex location in the holographic media;

multiplexing a second plurality of holograms with the second hologram at a second multiplex location in the holographic media.

30. The method of claim 29 wherein the first plurality of holograms are angle multiplexed at the first multiplex location and the second plurality of holograms are angle multiplexed at the second multiplex location.

31. The method of claim 29 wherein the first plurality of holograms are wavelength multiplexed at the first multiplex location and the second plurality of holograms are wavelength multiplexed at the second multiplex location.

32. The method of claim 1 wherein:

creating the first hologram includes placing the beam waist of the first signal beam outside the holographic media; and

creating the second hologram includes placing the beam waist of the second signal beam outside the holographic media.

33. The method of claim 1 including locating the holographic media at an image plane of the first signal beam.

34. The method of claim 1 including locating the holographic media at a Fourier plane of the first signal beam.

70. The method of claim 1, wherein the second reference beam is the same as the first reference beam.

2. A method for holographic recording, comprising:

creating a first hologram in a holographic media using a first reference beam and a first signal beam comprising page-wise data modulated by a spatial light modulator (SLM), the first signal beam having a beam waist;

creating a second hologram using a second reference beam and a second signal beam, the second signal beam having a beam waist;

overlapping at least a portion of the second hologram with the first hologram; and

separating the first hologram from the second hologram such that no portion of the beam waist of the first signal beam occurs at the same location as any portion of beam waist of the second signal beam;

reconstructing the first hologram in a first portion of an output beam;

reconstructing at least the second hologram in a second portion of the output beam; and

filtering the output beam to substantially contain only a reconstruction of the first hologram, wherein the SLM is an amplitude modulating SLM, a phase modulating SLM or combinations thereof.

3. The method of claim 2 wherein filtering the output beam includes placing a filter block in the output beam, the filter block having an aperture which allows information from the first hologram to pass through the filter block.

4. The method of claim 3 wherein:

the first portion of the output beam has a first output waist and the second portion of the output beam has a second output waist; and

filtering the output beam includes;

placing the aperture of the filter block at a location of the first output waist; and

blocking transmission of the second portion of the output beam at the second output waist.

5. The method of claim 4 wherein one dimension of the aperture is the Nyquist size.

6. The method of claim 4 wherein one dimension of the aperture is twice the Nyquist size.

7. The method of claim 2 wherein creating the first hologram includes:

placing a spatial light modulator (SLM) in the path of an incident beam to generate the first signal beam; and

placing a lens in the path of the first signal beam between the SLM and the holographic media.

8. The method of claim 7 wherein reconstructing the first hologram includes using a readout beam to create the output beam wherein the readout beam is the same as the first reference beam.

9. The method of claim 8 wherein reconstructing the first hologram includes using a readout beam to create the output beam, wherein the readout beam is the phase conjugate of the first reference beam.

10. The method of claim 9 including detecting a readout of the first portion of the output beam in a detector that is integrated with the SLM.

11. The method of claim 2 wherein creating the first hologram includes:

placing a spatial light modulator (SLM) in the path of an incident beam to generate the first signal beam; and

placing a lens in the path of the incident beam before the incident beam reaches the SLM; and

transmitting the signal beam from the SLM to the holographic media without passing the signal beam through a lens.

12. The method of claim 11 wherein reconstructing the first hologram includes using a readout beam to create the output beam, wherein the readout beam is the phase conjugate of the first reference beam.

13. The method of claim 12 including detecting a first portion of the output beam in a detector that is integrated with the SLM.

14. The method of claim 2 wherein filtering the output beam includes placing an angular filter in the output beam.

15. The method of claim 14 wherein the angular filter is a layered film.

16. The method of claim 14 wherein the angular filter is a holographic optical element (HOE).

17. The method of claim 14 wherein reconstructing the first hologram includes using a readout beam to create the output beam, wherein the readout beam is the phase conjugate of the first reference beam.

18. The method of claim 2 including filtering the first signal beam before forming a hologram to limit the bandwidth of the first signal beam.

19. The method of claim 18 wherein:

filtering the first signal beam includes filtering the signal beam with one of either an angular filter and a filter block; and

filtering the output beam includes filtering the output beam with one of either an angular filter and a filter block.

20. The method of claim 2 wherein:

creating the first hologram includes placing a first waist of the first signal beam inside the holographic media; and

creating the second hologram includes placing a first waist of the second signal beam inside the holographic media.

21. The method of claim 20 including:

generating a second waist of the first signal beam outside the holographic media;

generating a second waist of the output beam outside the holographic media; and

blocking the second portion of the output beam outside the holographic media at the second waist of the output beam.

22. The method of claim 21 wherein reconstructing the first hologram includes using a readout beam to create the output beam wherein the readout beam is the same as the first reference beam.

23. The method of claim 21 wherein reconstructing the first hologram includes using a readout beam to create the output beam, wherein the readout beam is the phase conjugate of the first reference beam.

24. The method of claim 23 including:

detecting the first portion of the output beam in a detector; and

passing the first portion of the output beam through a waveplate and a polarized beam splitter before detecting the first portion of the output beam.

25. The method of claim 20 including passing the first object beam through a phase element prior to reaching the holographic media.

26. The method of claim 2 wherein filtering the output beam includes forming a filter that is integrated with the holographic media, the filter having at least one aperture.

27. The method of claim 2 including:

locating the holographic media at an image plane of the first signal beam such that the beam waist of the first signal beam is projected into the holographic media;

projecting the first signal beam through a first angular filter before projecting the first signal beam into the holographic media; and

wherein filtering the signal beam includes projecting the output beam through a second angular filter.

28. The method of claim 27 including generating the output beam using a readout beam that is the same as the first reference beam.

38. The method of claim 2 including:

imaging the first signal beam on a first spot in the holographic medium in a first direction; and

Fourier transforming the first signal beam on the first spot in the holographic medium in a direction orthogonal to the first direction.

35. A method for reading out a first hologram created in a holographic media from a first signal beam comprising page-wise data and a first reference beam, the first hologram overlapping in the holographic media with a portion of at least a second hologram created by a second signal beam and a reference beam that is the same as the first reference beam such that substantially no portion of a beam waist of the first signal beam occurs at the same location as any portion of a beam waist of the second signal beam, including:

reconstructing the first hologram in a first portion of an output beam and reconstructing at least the second hologram in a second portion of the output beam; and

filtering the output beam to substantially contain only a reconstruction of the first hologram.

36. The method of claim 35 including locating the holographic media at an image plane of the first signal beam.

37. The method of claim 35 including locating the holographic media at a Fourier plane of the first signal beam.

39. An apparatus for hologram recording comprising:

a spatial light modulator (SLM) located in a path of an incident beam to generate a first signal beam;

the first signal beam and a first reference beam generating a first hologram in a holographic medium the first signal beam having a first beam waist;

a second signal beam and a second reference beam, the second signal beam and the second reference beam generating a second hologram in a holographic medium the second signal beam having a second beam waist, at least a portion of the first hologram spatially overlapping with at least a portion of the second hologram in the holographic media such that substantially no portion of the waist of the first signal beam occurs in the same location in the holographic media as any portion of the waist of the second signal beam, wherein the SLM is an amplitude modulating SLM, a phase modulating SLM or combinations thereof.

54. The apparatus of claim 39 including:

a first plurality of holograms multiplexed with the first hologram at a location of the first hologram in the holographic media; and

a second plurality of holograms multiplexed with the second hologram at a location of the second hologram in the holographic media.

55. The method of claim 54 wherein the first plurality of holograms are angle multiplexed at the first multiplex location and the second plurality of holograms are angle multiplexed at the second multiplex location.

56. The method of claim 54 wherein the first plurality of holograms are wavelength multiplexed at the first multiplex location and the second plurality of holograms are wavelength multiplexed at the second multiplex location.

57. The apparatus of claim 39 wherein in forming the first hologram the first waist is located outside the holographic media and in forming the second hologram the second waist is located outside the holographic media.

58. The apparatus of claim 39 wherein an image plane of the first signal beam is projected inside the holographic media.

59. The apparatus of claim 39 wherein a Fourier plane of the first signal beam is projected inside the holographic media.

63. The apparatus of claim 39 wherein the first signal beam is imaged at an image plane of the first signal beam in a first direction on a spot in the holographic media and Fourier transformed on the spot in the holographic media in a second direction orthogonal to the first direction.

40. An apparatus for reading a hologram, comprising:

a first reference beam adapted to read a holographic media comprising a first hologram comprising page-wise data and a second hologram comprising page-wise data,

wherein at least a portion of the first hologram spatially overlaps with at least a portion of the second hologram in the holographic medium and the apparatus is adapted to produce an output beam from the first reference beam and at least the first hologram and the second hologram,

wherein the output beam comprises a first reconstructed signal beam with a first beam waist and a second reconstructed signal beam with a second beam waist such that substantially no portion of the waist of the first reconstructed signal beam occurs in the same location as any portion of the waist of the second reconstructed signal beam,

wherein the apparatus further comprises;

a first filter adapted to filter a substantial portion of the second reconstructed signal beam out of the output beam and a detector adapted to detect the output beam.

41. The apparatus of claim 40 wherein the first filter includes an opaque filter block having an aperture.

42. The apparatus of claim 41 wherein:

in reproducing the first hologram the aperture in the opaque filter block is located at the first beam waist and

transmission of the second reconstructed signal beam of the output beam is blocked at the second beam waist.

43. The apparatus of claim 42 wherein one dimension of the aperture is the Nyquist size.

44. The apparatus of claim 42 wherein one dimension of the aperture is twice the Nyquist size.

45. The apparatus of claim 40 further including a readout beam that generates the output beam wherein the readout beam is the same as the first reference beam.

46. The apparatus of claim 40 further including a readout beam that generates the output beam wherein the readout beam is the phase conjugate of the first reference beam.

47. The apparatus of claim 40 wherein the filter includes an angular filter.

48. The apparatus of claim 47 wherein the angular filter comprises layers of film.

49. The apparatus of claim 47 wherein the angular filter comprises an HOE.

50. The apparatus of claim 47 including a readout beam to generate the output beam wherein the readout beam is the phase conjugate of the first reference beam.

51. The apparatus of claim 40 including a second filter placed in a path of an object beam to limit the bandwidth of the object beam.

52. The apparatus of claim 51 wherein:

the first filter includes one of either an angular filter and a filter block having an aperture; and

the second filter includes one of either an angular filter and a filter block having an aperture.

53. The apparatus of claim 40 wherein the first filter is integrated with the holographic media.

71. The apparatus of claim 40, further comprising a detector.

60. An apparatus for reading out a first hologram created in a holographic media from a first signal beam comprising page-wise data and a reference beam, the first hologram overlapping in the holographic media with a portion of at least a second hologram created by a second signal beam and the reference beam such that substantially no portion of a beam waist of the first signal beam occurs at the same location as any portion of a beam waist of the second signal beam, including:

an output beam having;

a first portion in which the first hologram is read out;

and at least a second portion in which the second hologram is read out; and

a filter in the output beam that filters the output beam to contain substantially only a reconstruction of the first hologram.

61. The apparatus of claim 60 including locating the holographic media at an image plane of the first signal beam.

62. The apparatus of claim 60 including locating the holographic media at a Fourier plane of the first signal beam.

64. A holographic media including:

a first plurality of holograms comprising page-wise data multiplexed with a first hologram at a first location in the holographic media, and

a second plurality of holograms multiplexed with a second hologram at a second location in the holographic media, the second hologram created by a second signal beam and a second reference beam that is the same as the first reference beam the second signal beam having a second beam waist, wherein a portion of the first hologram overlaps with a portion of the second hologram and the first beam waist does not substantially occur at the same location as the second beam waist.

65. The holographic media of claim 64 wherein the holographic media is in the form of a disk and the first plurality of holograms and the second plurality of holograms are overlapped in a circular formation.

66. The holographic media of claim 64 wherein the first plurality of holograms and the second plurality of holograms are overlapped in a line.

67. The holographic media of claim 66 wherein the holographic media is in the form of a card.

68. The holographic media of claim 66 wherein the holographic media is in the form of a tape.

69. A method of replicating multiplexed holograms in the holographic media of claim 64 including:

placing a blank holographic media adjacent to the holographic media of claim 64;

projecting a readout beam through the holographic media of claim 64 to generate an output beam, the readout beam being the same as the first reference beam; and

recording at least the first and second holograms into the blank holographic media using the output beam.