Storage medium having a layer of micro-optical lenses each lens generating an evanescent field

• US 5,910,940 A
• Filed: 11/18/1997
• Issued: 06/08/1999
• Est. Priority Date: 10/08/1996
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Guerra, John M.
• Primary Examiner(s): Swann, Tod R.
• Assistant Examiner(s): CHU, KIM KWOK
• Application Number:
  US08/972,778
• Time in Patent Office: 567 Days
• Field of Search: 369/275.1, 369/116, 369/284, 369/112, 369/126, 369/43, 356/359, 356/345, 359/819, 359/664, 250/216
• US Class Current: 369/275.1
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G11B 11/105 using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
• CPC Class Codes: G11B 11/10532 Heads
• CPC Class Codes: G11B 11/1055 Disposition or mounting of transducers relative to record carriers
• CPC Class Codes: G11B 11/10584 characterised by the form, e.g. comprising mechanical protection elements
• CPC Class Codes: G11B 2007/0013 for carriers having multiple discrete layers
• CPC Class Codes: G11B 23/0316 Constructional details, e.g. shape
• CPC Class Codes: G11B 7/004 Recording, reproducing or erasing methods; Read, write or erase circuits therefor magneto-optical systems G11B11/105
• CPC Class Codes: G11B 7/0065 Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/12 Heads, e.g. forming of the optical beam spot or modulation of the optical beam disposition or mounting of head elements within housing or with provision for moving of light source, optical beam or detector, irrelevant to the transducing method G11B7/08 ; modulating lasers H01S3/10; controlling the intensity, colour, phase, polarisation or direction of light beams arriving from an independent light source, e.g. switching gating or modulating G02F1/00
• CPC Class Codes: G11B 7/1353 Diffractive elements, e.g. holograms or gratings diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44
• CPC Class Codes: G11B 7/1365 Separate or integrated refractive elements, e.g. wave plates
• CPC Class Codes: G11B 7/1372 Lenses
• CPC Class Codes: G11B 7/1381 Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops G11B7/1353 - G11B7/1369 take precedence
• CPC Class Codes: G11B 7/1387 using the near-field effect
• CPC Class Codes: G11B 7/14 specially adapted to record on, or to reproduce from, more than one track simultaneously
• CPC Class Codes: G11B 7/24065 Layers assisting in recording or reproduction below the optical diffraction limit, e.g. non-linear optical layers or structures cover layers for near-field media G11B7/24059
• CPC Class Codes: G11B 7/26 Apparatus or processes specially adapted for the manufacture of record carriers
• CPC Class Codes: Y10S 977/712 formed from plural layers of nanosized material, e.g. stacked structures
• CPC Class Codes: Y10S 977/773 Nanoparticle, i.e. structure having three dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/834 : Optical properties of nanomaterial, e.g. specified transparency, opacity, or index of refraction
• CPC Class Codes: Y10S 977/943 : Information storage or retrieval using nanostructure

Abstract

A medium suitable for the optical storage and retrieval of information comprising a substrate, an active layer for retention of the data, and an overlying optical layer, or layers for double-sided. The optical layer serves to produce an evanescent field in or adjacent to the active layer in response to an incident beam of radiation. The evanescent field is frustrated or attenuated by the data in the active layer and produces a signal.

Claims

1. A storage medium, suitable for use with an external source of illumination for the storage and retrieval of information, said storage medium comprising:

an optical layer disposed to receive the illumination, said optical layer comprising a plurality of micro-optical elements, each said micro-optical element having a first index of refraction and configured such that illumination incident upon said micro-optic element produces local evanescent field illumination extending from said optical layer, and

an active layer disposed to receive said evanescent field illumination, said active layer being responsive to said evanescent field illumination such that a predetermined amount of said evanescent field illumination impinging upon a portion of said active layer produces an artifact within said portion.

2. The storage medium of claim 1 wherein said active layer comprises at least one of the following materials:

crystalline phase change material, amorphous phase change material, dye absorber, chalcogenide glass and compounds, polymer, quartz, magneto-optical material, photo-refractive polymer, photo-refractive crystal, photographic emulsion, fluorescent material, photoresist, binary medium, or semiconductor detector array.

3. The storage medium of claim 1 wherein said artifact comprises a change in at least one of the following characteristics of said active layer:

index of refraction, scatter, optical phase, polarization, diffraction, refraction, constructive interference, destructive interference, absorption, magneto-optical Kerr rotation, surface topography, chemical structure, mechanical structure (e.g., adhesion), or material phase state.

4. The storage medium of claim 1 wherein said micro-optical element further comprises a prism-like optic.

5. The storage medium of claim 4 wherein said prism-like optic comprises a truncated prism.

6. The storage medium of claim 1 wherein micro-optical element further comprises a lens having curvature in at least one meridian.

7. The storage medium of claim 6 wherein said curvature is aplanatic.

8. The storage medium of claim 6 wherein said curvature is aspherical.

9. The storage medium of claim 1 wherein said optical layer further comprises a resonant structure.

10. The storage medium of claim 9 wherein said resonant structure comprises a layer of material having a second index of refraction.

11. The storage medium of claim 10 wherein said second index of refraction is less than said first index of refraction.

12. The storage medium of claim 10 wherein said second index of refraction is greater than or equal to said first index of refraction.

13. The storage medium of claim 10 wherein said material comprises a metal.

14. The storage medium of claim 13 wherein the thickness of said metal layer is selected such that a surface plasmon resonant field is generated in response to the incident illumination.

15. The storage medium of claim 1 wherein said optical layer further comprises a diffraction grating.

16. The storage medium of claim 15 wherein said diffraction grating has a spatial period smaller than the illumination wavelength.

17. The storage medium of claim 1 further comprising a substrate disposed upon said active layer.

18. The storage medium of claim 17 wherein said substrate comprises one of the following materials:

polycarbonate, mylar, glass, acrylic, and polyester.

19. The storage medium of claim 17 wherein said substrate comprises means for providing tracking guidance.

20. The storage medium of claim 1 further comprising a layer of material having a third index of refraction disposed between said active layer and said optical layer, said third index of refraction being smaller than said first index of refraction.

21. The storage medium of claim 20 wherein said material comprises air.

22. The storage medium of claim 20 wherein said layer of material comprises a thickness of dimension less than the wavelength λ

of the source of illumination.

23. The storage medium of claim 1 further comprising a housing.

24. The storage medium of claim 23 wherein said housing comprises a window.

25. The storage medium of claim 24 wherein said window comprises micro-optical elements.

26. The storage medium of claim 1 wherein said optical layer further comprises means for providing tracking guidance.

27. The storage medium of claim 26 wherein said means for providing tracking guidance comprises secondary optical artifacts.

28. The storage medium of claim 1 wherein said micro-optical element comprises dihedral surfaces.

29. The storage medium of claim 1 further comprising a second active layer disposed proximal to said active layer.

30. The storage medium of claim 29 further comprising a separation layer having a third index of refraction, said separation layer disposed between said active layer and said second active layer.

31. The storage medium of claim 30 wherein said third index of refraction is less than said first index of refraction.

32. The storage medium of claim 1 wherein said active layer comprises means for providing tracking guidance.

33. A storage medium, suitable for use with an external source of illumination, having a wavelength λ

, for the storage and retrieval of information, said storage medium comprising;

an optical layer disposed to receive the illumination, said optical layer comprising a plurality of micro-optical elements, each said micro-optical element having a first index of refraction and configured such that illumination incident upon said micro-optic element produces propagating illumination extending from said optical layer, said optical layer further comprising an interference reference surface, and

an active layer disposed to receive said propagating illumination, said active layer being responsive to said propagating illumination such that a predetermined amount of said propagating illumination impinging upon a portion of said active layer produces an artifact within said portion.

34. The storage medium of claim 33 wherein said micro-optical element further comprises a prism-like optic.

35. The storage medium of claim 34 wherein said prism-like optic comprises a truncated prism.

36. The storage medium of claim 33 further comprising a substrate disposed upon said active layer.

37. The storage medium of claim 36 wherein said substrate comprises one of the following materials:

polycarbonate, mylar, glass, acrylic, and polyester.

38. The storage medium of claim 36 wherein said substrate comprises means for providing tracking guidance.

39. The storage medium of claim 33 wherein said optical layer further comprises means for providing tracking guidance.

40. The storage medium of claim 39 wherein said means for providing tracking guidance comprises secondary optical artifacts.

41. The storage medium of claim 33 further comprising a second active layer disposed proximal to said active layer.

42. The storage medium of claim 41 further comprising a separation layer having a third index of refraction, said separation layer disposed between said active layer and said second active layer.

43. The storage medium of claim 42 wherein said third index of refraction is less than said first index of refraction.

44. The storage medium of claim 33 wherein said micro-optical element comprises dihedral surfaces.

45. A storage medium, suitable for use with an external source of illumination for the storage and retrieval of information, said storage medium comprising:

a first optical layer comprising micro-optical elements, said first optical layer further comprising a first index of refraction and disposed to receive the illumination and generate an evanescent field illumination therefrom;

a second optical layer comprising a second index of refraction, said second optical layer disposed to receive said evanescent field illumination and generate a secondary evanescent field illumination therefrom, and

an active layer disposed to receive said secondary evanescent field illumination, said active layer being responsive to said secondary evanescent field illumination such that a predetermined amount of said secondary evanescent field illumination impinging upon a portion of said active layer produces an artifact within said portion.

46. The storage medium of claim 45 wherein said second optical layer comprises a total internal reflection surface.

47. The storage medium of claim 45 wherein said first index of refraction is substantially equivalent to said second index of refraction.

48. The storage medium of claim 45 wherein said second optical layer comprises a resonant structure.

49. The storage medium of claim 48 wherein said resonant structure comprises a layer of material comprising an index of refraction lower than said first optical layer index of refraction.

50. The storage medium of claim 49 wherein said material comprises air.

51. The storage medium of claim 45 wherein said first optical layer combines with said second optical layer to form aplanatic optical elements.

52. The storage medium of claim 45 wherein said active layer comprises at least one of the following materials:

crystalline phase change material, amorphous phase change material, dye absorber, chalcogenide glass and compounds, polymer, quartz, magneto-optical material, photo-refractive polymer, photo-refractive crystal, photographic emulsion, fluorescent material, photoresist, binary medium, or semiconductor detector array.

53. The storage medium of claim 45 wherein said artifact comprises a change in at least one of the following characteristics of said active layer:

index of refraction, scatter, optical phase, polarization, diffraction, refraction, constructive interference, destructive interference, absorption, magneto-optical Kerr rotation, surface topography, chemical structure, mechanical structure (e.g., adhesion), or material phase state.

54. The storage medium of claim 45 wherein said micro-optical element further comprises a prism-like optic.

55. The storage medium of claim 54 wherein said prism-like optic comprises a truncated prism.

56. The storage medium of claim 45 wherein micro-optical element further comprises a lens having curvature in at least one meridian.

57. The storage medium of claim 56 wherein said curvature is aplanatic.

58. The storage medium of claim 56 wherein said curvature is aspherical.

59. The storage medium of claim 45 further comprising a metal disposed upon said second optical layer.

60. The storage medium of claim 59 wherein the thickness of said metal layer is selected such that a surface plasmon resonant field is generated in response to the incident illumination.

61. The storage medium of claim 45 wherein said second optical layer further comprises a diffraction grating.

62. The storage medium of claim 61 wherein said diffraction grating has a spatial period smaller than the illumination wavelength.

63. The storage medium of claim 45 further comprising a substrate disposed upon said active layer.

64. The storage medium of claim 63 wherein said substrate comprises one of the following materials:

polycarbonate, mylar, glass, acrylic, and polyester.

65. The storage medium of claim 45 further comprising a layer of material having a third index of refraction disposed between said active layer and said optical layer, said third index of refraction being smaller than said first index of refraction.

66. The storage medium of claim 65 wherein said layer of material comprises a thickness of dimension less than the wavelength λ

of the source of illumination.

67. The storage medium of claim 45 further comprising a housing.

68. The storage medium of claim 67 wherein said housing comprises a window.

69. The storage medium of claim 68 wherein said first optical layer is disposed upon said window.

70. The storage medium of claim 45 wherein said second optical layer further comprises means for providing tracking guidance.

71. The storage medium of claim 70 wherein said means for providing tracking guidance comprises secondary optical artifacts.

72. The storage medium of claim 45 wherein said active layer comprises means for providing tracking guidance.

73. The storage medium of claim 63 wherein said substrate comprises means for providing tracking guidance.

74. The storage medium of claim 45 further comprising a second active layer disposed proximal to said active layer.

75. The storage medium of claim 74 further comprising a separation layer having a third index of refraction, said separation layer disposed between said active layer and said second active layer.

76. The storage medium of claim 75 wherein said third index of refraction is less than said first index of refraction.

77. The storage medium of claim 45 wherein said active layer comprises at least one of the following materials:

crystalline phase change material, amorphous phase change material, dye absorber, chalcogenide glass and compounds, polymer, quartz, magneto-optical material, photo-refractive polymer, photo-refractive crystal, photographic emulsion, fluorescent material, photoresist, binary medium, or semiconductor detector array.

78. The storage medium of claim 45 wherein said artifact comprises a change in at least one of the following characteristics of said active layer:

index of refraction, scatter, optical phase, polarization, diffraction, refraction, constructive interference, destructive interference, absorption, magneto-optical Kerr rotation, surface topography, chemical structure, mechanical structure (e.g., adhesion), or material phase state.

79. A storage medium, suitable for use with an external proximal source of evanescent field illumination provided by means of an optical element having an index of refraction for the storage and retrieval of information, said storage medium comprising:

an optical layer comprising an index of refraction, said optical layer disposed to receive the evanescent field illumination and generate secondary evanescent field illumination therefrom, and

an active layer disposed to receive said secondary evanescent field illumination, said active layer being responsive to said secondary evanescent field illumination such that a predetermined amount of said secondary evanescent field illumination impinging upon a portion of said active layer produces an artifact within said portion.

80. The storage medium of claim 79 wherein said optical layer comprises a total internal reflection surface.

81. The storage medium of claim 79 wherein said optical layer index of refraction is substantially equivalent to the optical element index of refraction.

82. The storage medium of claim 79 wherein said optical layer comprises a resonant structure.

83. The storage medium of claim 82 wherein said resonant structure comprises a layer of material comprising an index of refraction lower than the optical element index of refraction.

84. The storage medium of claim 83 wherein said material comprises air.

85. The storage medium of claim 79 wherein said optical layer combines with the optical element to form an aplanatic optical element.

86. The storage medium of claim 79 further comprising a metal disposed upon said optical layer.

87. The storage medium of claim 86 wherein the thickness of said metal layer is selected such that a surface plasmon resonant field is generated in response to the incident illumination.

88. The storage medium of claim 79 wherein said optical layer further comprises a diffraction grating.

89. The storage medium of claim 88 wherein said diffraction grating has a spatial period smaller than the illumination wavelength.

90. The storage medium of claim 79 further comprising a substrate disposed upon said active layer.

91. The storage medium of claim 90 wherein said substrate comprises one of the following materials:

polycarbonate, mylar, glass, acrylic, and polyester.

92. The storage medium of claim 90 wherein said substrate comprises means for providing tracking guidance.

93. The storage medium of claim 79 further comprising a housing.

94. The storage medium of claim 93 wherein said housing comprises a window.

95. The storage medium of claim 79 wherein said optical layer further comprises means for providing tracking guidance.

96. The storage medium of claim 95 wherein said means for providing tracking guidance comprises secondary optical artifacts.

97. The storage medium of claim 79 wherein said active layer comprises means for providing tracking guidance.

98. The storage medium of claim 79 further comprising a second active layer disposed proximal to said active layer.

99. The storage medium of claim 98 further comprising a separation layer having a third index of refraction, said separation layer disposed between said active layer and said second active layer.

100. The storage medium of claim 99 wherein said third index of refraction is less than said first index of refraction.