Optical random access memory

• US 5,541,888 A
• Filed: 11/03/1994
• Issued: 07/30/1996
• Est. Priority Date: 12/30/1991
• Status: Expired due to Fees

• Current Assignee: RITEK Corporation
• Original Assignee: Information Optics Corporation
• Inventors: Russell, James T.
• Primary Examiner(s): Nguyen, Viet Q.
• Application Number:
  US08/334,185
• Time in Patent Office: 635 Days
• Field of Search: 365/234, 365/235, 365/64, 365/215, 365/216, 369/112, 369/103, 369/116
• US Class Current: 365/234
• CPC Class Codes: G11C 11/56 using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency
• CPC Class Codes: G11C 13/04 using optical elements ; using other beam accessed elements, e.g. electron or ion beam
• CPC Class Codes: G11C 13/041 using photochromic storage elements G11C13/042 takes precedence
• CPC Class Codes: G11C 7/005 with combined beam-and individual cell access

Abstract

An optical memory is disclosed in which data is stored in an optical data layer capable of selectively altering light such as by changeable transmissivity, reflectivity, polarization, and/or phase. The data is illuminated by controllable light sources and an array of multi-surface imaging lenslets project the image onto a common array of light sensors. Data is organized into a plurality of regions or patches (called pages) and by selective illumination of each data page, one of the lenslets images the selected data page onto the light sensors. Light in the data image pattern strikes different ones of the arrayed light sensors, thereby outputting a pattern of binary bits in the form of electrical data signals. By selectively and sequentially illuminating different ones of the data regions (pages) on the data layer, correspondingly different data patterns are imaged by the corresponding lenslets onto the common sensor array, thereby enabling many stored data pages to be retrieved by multiplexing at electro-optical speed.

Claims

1. An optical data system comprising:

an optical data means for storing data as light altering characteristics and being organized into a plurality (P) of juxtaposed data regions each having capacity to store (B) bits of data;

controllable light source means for selectively illuminating at least one of said data regions of said optical data means;

data imaging lens means having a plurality of juxtaposed lenslets each being shaped and arranged in such proximity to and in optical registration with a different one of said juxtaposed data regions so that the image resolving power thereof is substantially uniform over the field of view of that data region to form an image thereof on a common image surface spaced from said data means and lens means;

sensor means having a plurality (S) of juxtaposed light sensors arranged at said image surface for sensing data as a light image corresponding to an illuminated data region; and

data signal output means coupled to said sensor means for outputting data signals representing said data of an illuminated and imaged data region.

2. The system of claim 1 wherein said data imaging lens means includes diffraction means for correcting the imaging of each data region.

3. The system of claim 1 wherein said plurality of lenslets of said data imaging lens means include contoured refractive surfaces of a continuous layer of optical material and said data imaging lens means further comprising diffraction means and field lens means, said diffraction means selectively correcting data image light rays passing through said lenslets, and said field lens means directing light patterns imaged through said diffraction means of different lenslets onto said image surface.

4. The system of claim 2 wherein said diffraction means comprises a plurality of overlapping grating patterns arrayed so that individual grating patterns are in optical alignment with individual ones of said data regions.

5. The system of claim 2 wherein said diffraction means comprise holographic means having a plurality of overlapping holographic image correction patterns arrayed so that individual holographic correction patterns are in optical alignment with individual ones of said data regions.

6. The system of claim 2 further comprising a field lens disposed between said diffraction means and said sensor means for bending light ray patterns originating from different ones of said data regions and lenslets onto said common image surface containing said sensor means.

7. The system of claim 1 wherein each of said lenslets has a Numerical Aperture in a range of 0.35 to 0.6, and a field of view substantially equal to an area of one of said data regions.

8. The system of claim 1 wherein each of said lenslets is comprised of at least one functionally aspherical optical element.

9. The system of claim 8 wherein said aspherical surface of each of said lenslets is disposed adjacent said data means.

10. The system of claim 1 wherein said data means and said lens means are formed as a unitary layered structure so as to maintain optical registration therebetween.

11. The system of claim 10 wherein said unitary layered structure of said data means and said lens means comprises a data layer having said data regions arrayed in juxtaposition thereon, a lenslet layer having said plurality of lenslets formed thereon as an array of juxtaposed contoured lens surfaces having their individual optical axes aligned with registering ones of said data regions, and a transparent spacer layer disposed between said data layer and said lenslet layer.

12. The system of claim 11, wherein said transparent spacer layer optically immerses said data of said data layer to reduce an angle of image ray divergence.

13. The system of claim 11 wherein said juxtaposed contoured lens surfaces of said lenslets adjacent said transparent spacer layer are aspherical to provide substantially uniform resolution across the field of data in the aligned data region.

14. The system of claim 13 wherein each said data region has a contour toward said transparent spacer layer and said lenslet layer has second optical lens surfaces of said lenslets opposite from said transparent spacer that are substantially spherical.

15. The system of claim 14, wherein said second lens surfaces have predetermined aspheric factors on a substantially spherical surface.

16. The system of claim 10 further comprising structural means for receiving and releasably retaining said unitary layered

17. The system of claim 1 wherein said sensor means comprises a plurality of sensor elements arrayed in a pattern that corresponds, on an enlarged image scale, to data in one of said data regions of said data means.

18. The system of claim 1 wherein said data regions on said data means are arrayed in juxtaposed close-packed cells and said sensor means has a plurality of said sensor elements arrayed to form said common image surface and having a perimeter in the shape of but larger than one of said data regions.

19. The system of claim 18 wherein each of said juxtaposed close-packed cells has a shape resembling a hexagon.

20. The system of claim 1 wherein said controllable light source means comprises an array of juxtaposed solid state light generating elements.

21. The system of claim 20, wherein said light generating elements are organized into groups, each group for illumination of a different one of said data regions.

22. The system of claim 21 wherein each group of said solid state light generating elements has a generally hexagonal shaped cell and means for selectively energizing each said group to cause a hexagonal-shaped patch of light for illuminating a corresponding one of said separate data regions of said data means.

23. The system of claim 21 wherein said light generating elements comprise laser diodes.

24. The system of claim 1 wherein said data means is a light transmissive data means.

25. The system of claim 1 wherein said data means is a light reflective data means.

26. The system of claim 1 wherein said data means is a light polarizing data means.

27. The system of claim 26 wherein said light polarizing data means is a magneto-optic data means.

28. The optical system of claim 1, wherein said data bits are ≧

2.25 microns across and stored at a density of 2×

10⁷ or greater per cm².

29. The optical system of claim 28, wherein each said data region stores B≧

10⁶ bits and said plurality (S) of juxtaposed sensors and (B) bits of data stored in each data region has the relationship S≧

B.

30. The optical system of claim 1, wherein said (B) bits of data is defined by B≧

10⁶ and said plurality of (P) data regions is P≧

100 for a data capacity of the system equal to or greater than 100 megabits.

31. The optical system of claim 28, wherein said optical data means comprises data supporting means that has a substantially flat surface of area equal to about 6.5 cm².

32. The optical system of claim 1, wherein each said lenslet has an effective focal length of substantially 1.0 mm or less and is disposed with its first surface at substantially 0.6 mm or less from said data means.

33. The optical system of claim 32, wherein each said data region has a dimension of d across its area, and each said lenslet has a first surface spaced within 1/10 d to 3/4 d of said data means, and wherein said image surface at which said sensors are arranged is spaced from said lenslets by a distance greater. than d.

34. The optical data system of claim 1 wherein said sensor means comprises:

an array of solid state sensor elements formed in an integrated circuit structure providing said common image surface, and a plurality of adaptive threshold sensing circuit means for providing a variable, adaptive light sensing threshold to data images at each of said sensor elements in response to receipt of light on adjacent sensor elements.

35. The optical data system of claim 34 wherein said array of solid state sensor elements comprises a plurality of charge coupled devices.

36. The optical data system of claim 34 wherein said array of solid state sensor elements comprises at least one PIN diode.

37. The optical data system of claim 1, further comprising adaptive threshold sensing circuit means for providing a variable, adaptive light sensing threshold to data images incident on each of said sensors.

84. The system of claim 1, wherein each of said plurality of juxtaposed lenslets comprises at least one refractive surface.

85. The system of claim 1, wherein each of said plurality of juxtaposed lenslets comprises at least one diffractive surface.

38. An optical data system comprising:

an optical data means for storing data as light altering characteristics having a density on the order of one bit per square micron and being organized into a plurality of juxtaposed data regions each adapted to store a field of bits of data;

controllable light source means for selectively illuminating at least one of said data regions of said optical data means;

lens means having a plurality of juxtaposed lenslets configured to resolve objects on the order of one micron or less and each arranged proximate and in optical registration with a separate one of said juxtaposed data regions for forming an image of the bit field thereof on a common image surface spaced from said data means and lens means;

sensor means having a plurality of juxtaposed light sensors arranged at said image surface for sensing said data as a light image of an illuminated one or more of said data regions; and

data signal output means coupled to said sensor means for outputting data signals representing said data of an illuminated and imaged data region.

39. An optical data system comprising:

an optical data means for storing data as light altering characteristics on a substantially planar data storage structure and being organized in an array of close packed, juxtaposed cells and each cell adapted to store data;

controllable light source means for selectively illuminating at least one of said cells of said optical data means;

data imaging optical means having an array of juxtaposed lens subsystems disposed so that each said lens subsystem is proximate to and in optical registration with a separate one of said cells and has a center-to-center spacing relative to adjacent lens subsystems that is substantially equal to the corresponding spacing between adjacent cells in said data storage structure, and wherein each said lens subsystem has a Numerical Aperture in the range of 0.35 to 0.6 and a field of view substantially equal to an area of the one of said cells in registration therewith for forming an image of data in said cell on a common image surface; and

sensor means having a plurality of juxtaposed light sensors arrayed at said common image surface for sensing data as light imaged from an illuminated said cell.

40. The optical data system of claim 39 wherein each of said lens subsystems has at least one refractive surface that is disposed within a distance d≦

than said center-to-center spacing of said lens subsystems.

41. The optical data system of claim 40 wherein said at least one refractive surface is aspherical.

42. The optical data system of claim 40 wherein each said lens subsystem has at least one diffractive surface disposed at a distance greater than d from said cell, and has overlapping diffractive areas so that overlapping data image rays from adjacent cells after passing through said refractive surface are diffractively altered by overlapping diffractive areas.

43. The optical data system of claim 39 wherein each of said lens subsystems has an optical stop located at a predetermined distance from a registering one of said cells, each of said lens subsystems having at least one refractive means between a corresponding one of said cells and said stop and having at least one diffractive means at a distance from said cell greater than that of said stop.

44. The optical data system of claim 43 wherein said diffractive means comprises a plurality of over-lapping diffractive patterns, each diffractive pattern encompassing an area that is greater than the spacing between the fields of view of each of said lens subsystems so that overlapping data image rays from adjacent cells are diffractively corrected by different but overlapping diffractive patterns.

45. The optical data system of claim 42 wherein said diffractive means includes a grating.

46. The optical data system of claim 42 wherein said diffractive means includes a holographic pattern.

86. The optical data system of claim 39 wherein each of said lens subsystems has at least one diffractive surface.

87. The optical data and lens structure of claim 86 wherein each of said lenslets has at least one diffractive surface.

88. The optical data and lens structure of claim 87 wherein each of said lenslets has a set of optically aligned surfaces, and at least one of said surfaces of each lenslet set is functionally aspherical.

47. An optical data system comprising:

an optical data means for storing data as light altering characteristics having a density in a range of the order of 10⁷ to 10⁸ bits per square cm and being organized into a plurality of (P) juxtaposed data regions each sized to store a field of (B) bits of data at said density;

controllable light source means for selectively illuminating at least one of said data regions of said optical data means;

lens means having a plurality of juxtaposed lenslets each arranged in optical registration with a separate one of said (P) juxtaposed data regions and shaped to resolve said field of (B) bits of data thereof at said density substantially uniformly over said region to form an image thereof on a common image surface spaced from said data means and lens means;

sensor means having a plurality of juxtaposed light sensors arranged at said image surface for sensing said field of (B) bits of data as a light image of an illuminated one or more of said data regions; and

data signal output means coupled to said sensor means for outputting data signals representing said field of (B) bits of data.

48. An optical data system comprising:

an optical data means for storing data as light altering characteristics and being organized into a plurality of juxtaposed data regions each having capacity to store bits of data;

controllable solid state light generator means for selectively illuminating at least one of said separate data regions of said optical data means;

data imaging lens means having a plurality of juxtaposed lenslets each having at least one functionally aspherical surface and arranged in such proximity to and in optical registration with a separate one of said juxtaposed data regions so that the image resolving power thereof is substantially uniform over the field of view of that data region to form an image thereof on a common image surface spaced from said data means and lens means;

sensor means having a plurality of juxtaposed solid state light sensors arranged at said common image surface for sensing data as a light image corresponding to an illuminated data region; and

data signal output means coupled to said sensor means for outputting data signals representing selective portions of said stored bits of data of an illuminated and imaged data region.

49. An optical data recording and retrieval system comprising:

read light source array means;

optical data record means disposed proximate to said read light source array means for being illuminated thereby;

lens array means comprising a plurality of substantially similar lenslets arrayed in a lens structure disposed proximate and affixed to said optical data record means, each said lenslet forming a distal image of a portion of said optical data record means illuminated by said read light source array means;

light sensor array means disposed to receive said image of said portion of said optical data record means illuminated by said read light source means, said sensor array means responding to said image to output data; and

recording light data composer means for producing a recording light data pattern and imaging same onto said optical data record means for storing said data pattern.

50. The optical data recording and retrieval system of claim 49 having a read mode and a recording mode, further comprising beam splitter means that in a read mode causes read data to be imaged in succession through said lens array means and said beam splitter means onto said light sensor array means, and that in a recording mode causes said recording light pattern produced by said recording light data composer means to be imaged in succession through said beam splitter means and said lens array means onto said optical data record means.

51. The optical data recording and retrieval system of claim 49 wherein said recording light data composer means comprises controllable light valve array means and recording light emitter means for generating said recording light data pattern by illuminating said light valve array means so that a recording image thereof is directed onto said optical data record for storage.

52. The optical data recording and retrieval system of claim 51 wherein said recording light emitter means comprises an array of selectively energized record light sources, one for imaging data through separate ones of said lenslets onto an associated portion of said optical data record means, and further comprising a record imaging lens means disposed between said array of selectively energized record light sources and said controllable light valve means.

53. The optical data recording and retrieval system of claim 49 wherein said recording light data composer means comprises controllable reflective modulators arrayed in a data pattern, and recording light means for generating said recording light data pattern by illuminating said controllable reflective modulators so as to cause a reflected recording image thereof, and optical means for directing said reflected recording image through a selected lenslet onto an associated portion of said optical data record means.

54. The optical data recording and retrieval system of claim 51 wherein said recording light data composer means comprises an array of light source elements disposed substantially coplanar with said light sensor array means, and further comprising light shutter means disposed proximate said lens array mean for controllably transmitting said recording light data pattern composed by said array of light source elements through a selected one or more of said lenslets onto the associated portion or portions of said optical data record means.

55. The optical data recording and retrieval system of claim 54 wherein said array of recording light source elements and said light sensor array means comprise solid state devices.

56. The optical data recording and retrieval system of claim 54 wherein said array of recording light source elements and said light sensor array means are mounted on a common circuit board.

57. The optical data recording and retrieval system of claim 56 wherein said common circuit board comprises a large scale integrated circuit.

58. The optical data recording and retrieval system of claim 49 wherein said light sensor array means comprises solid state devices, and said recording light data composer means comprises means for operating said solid state devices as light generators.

59. The optical data recording and retrieval system of claim 49 further comprising controllable optical shutter means for selectively blocking recording light data patterns from selected regions of said data means.

60. The optical data recording and retrieval system of claim 49 wherein said recording light data composer means comprises a plurality of recording light emitters arrayed in a pattern that complements data patterns on said data record means.

61. The optical data recording and retrieval system of claim 49 wherein said recording light data composer means comprises an array of micro lenses and adjacent thereto an array of recording light source means for imaging recording light patterns onto said data record means through said lens array means.

62. A method of recording and reading optical data, comprising the steps of:

composing a recording light data pattern by selectively operating light pattern controlling devices;

bonding an optical data record to a plurality of juxtaposed lenslets of a lens array using transparent bonding material;

optically forming a recording image of said recording light data pattern through one of the plurality of lenslets of the lens array onto a region of the optical data record, said region being in registration with said one of the plurality of lenslets;

storing said recording image formed on said optical data record; and

reading said optical data record by illuminating said region thereof storing said recording image.

63. The method of claim 62 wherein the step of reading comprises imaging said illuminated region of said optical data record onto an array of light sensors using the same one of the plurality of lenslets of the lens array through which said recording image was formed on said region of said optical data record.

64. The method of claim 63 comprising the step of immersing said optical data record in a transparent material disposed between said optical data record and said lens array before the step of optically forming a recording image.

65. An optical data recording system comprising:

a recording light data composer means for forming a pattern of changeable data to be recorded;

data storage means having a plurality of separate data storage regions each for storing data imaged thereon;

lens array means comprising a plurality of similar lenslets arrayed in a lens structure and disposed and structurally affixed proximate to said data storage means so that each separate lenslet is optically in registration with a separate one of said regions of said data storage means; and

optical selector means for causing composed data light patterns produced by said recording light data composer means to be imaged by said multiple lens array means onto a separate selected one of said data regions of said data storage means.

66. The optical data recording system of claim 65 wherein said optical selector means comprises controllable optical means for blocking recording light data to all but selected one or more of said regions of said data storage means.

67. The optical data recording system of claim 65 wherein said recording light data composer means comprises a plurality of recording light emitters arrayed in a pattern that complements each of the separate data storage regions on said data storage means.

68. The optical data recording system of claim 65 wherein said recording light data composer means comprises an array of micro lenses and an adjacent array of recording light emitter elements, said array of micro lenses directing recording light data composed on said array of recording light emitter elements into one of said lenslets of said lens array for being imaged thereby onto one of said data regions of said data storage means.

69. The optical data recording system of claim 65 having a read mode and a recording mode, further comprising beam splitter means that in a read mode causes read data to be imaged through said lens array means and said beam splitter means, and that in a recording mode causes said recording light pattern produced by said recording light data composer means to be imaged in succession through said beam splitter means and said lens array means onto said optical data record means.

70. The optical data recording system of claim 65 wherein said recording light data composer means comprises controllable light valve array means and recording light emitter means for generating said recording light data pattern by illuminating said light valve array means so that a recording image thereof is directed onto said optical data record for storage.

71. The optical data recording system of claim 65 wherein said recording light emitter means comprises an array of selectively energized record light sources, one for imaging data through separate ones of said lenslets onto a registering portion of said optical data record means, and further comprising a record imaging lens means disposed between said array of selectively energized record light sources and said controllable light valve means.

72. The optical data recording system of claim 65 wherein said recording light data composer means comprises controllable reflective modulators arrayed in a data pattern, and recording light means for generating said recording light data pattern by illuminating said controllable reflective modulators so as to cause a reflected recording image thereof, and optical means for directing said reflected recording image through a selected lenslet onto a registering portion of said optical data record means.

73. The optical data recording system of claim 65 wherein said light sensor array means comprises solid state devices, and said recording light data composer means comprises means for operating said solid state devices as light sources.

74. The optical data recording system of claim 65 further comprising controllable optical shutter means for selectively blocking recording light data patterns from selected regions of said data means.

75. The optical data recording system of claim 65 wherein said recording light data composer means comprises a plurality of recording light emitters arrayed in a pattern that complements data patterns to be stored on said data means.

76. The optical data recording and retrieval system of claim 69 wherein said recording light data composer means comprises an array of micro lenses and adjacent thereto an array of recording light generator means for imaging recording light patterns onto said data regions of said data record means through said beam splitter means and said lens array means.

77. An optical data and lens structure for an optical data system, comprising:

a data layer for storing data as light altering characteristics and being organized into a plurality of separate data regions;

a lens array comprising a plurality of lenslets disposed adjacent said data layer and each lenslet having an optical field of view respectively aligned with one of said separate data regions so that each lenslet is arranged for imaging optical data associated with one of said data regions; and

structural means interposed said data layer and said lens array so as to optically couple and mechanically fix said data layer to said lens array to form a structural unit.

78. The optical data and lens structure of claim 77 wherein said structural means comprises a transparent optical layer of bonding material.

79. The optical data and lens structure of claim 77, further comprising:

an additional layer of material bonded to said data layer on a side thereof opposite from said first named layer and said lens array.

80. The optical data and lens structure of claim 78, wherein said additional layer is a transparent protective cover material through which data illuminating light may be passed from an external light source to illuminate said data layer.

81. The optical data and lens structure of claim 78 wherein said additional layer is reflective so that light illuminating said data layer through said lens array is reflected back toward said lens array to form a reflected data image.

82. The optical data and lens structure of claim 77 wherein each said lenslet has first and second optical surfaces at least one of which is substantially aspherical.

83. The optical data and lens structure of claim 77 wherein said data layer at each said data region has an optical contour that optically coacts with the aligned one of said lenslets to image data at a distal image plane.