Holographic technique for illumination of image displays using ambient illumination

• US 6,339,486 B1
• Filed: 10/15/1999
• Issued: 01/15/2002
• Est. Priority Date: 10/16/1998
• Status: Expired due to Fees

• Current Assignee: Hoya Corporation
• Original Assignee: DigiLens Inc
• Inventors: Popovich, Milan M.
• Primary Examiner(s): Schuberg, Darren
• Assistant Examiner(s): Curtis, Craig
• Application Number:
  US09/419,273
• Time in Patent Office: 823 Days
• Field of Search: 359/1, 359/15, 359/22, 359/3, 359/4, 359/32, 348/40, 348/41, 348/343, 348/832, 353/31
• US Class Current: 359/15
• CPC Class Codes: G02B 30/52 the 3D volume being constructed from a stack or sequence of 2D planes, e.g. depth sampling systems
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence

Abstract

An apparatus and method is disclosed for illuminating an image display with ambient light using holographic techniques. The apparatus includes a pair of holographic optical elements each having a first surface aligned on a common axis so that the first surfaces of each optical element face each other. Each of the first and second optical elements diffracts first bandwidth light. The second holographic optical element, however, diffracts first bandwidth light received on the first surface facing the first surface of the first holographic optical element. The second holographic optical element diffracts first bandwidth light received on its first surface, the diffracted light emerging from the first surface. The first and second holographic optical elements are switchable between inactive and active states. In the inactive state, each of the first and second holographic optical elements transmits substantially all light without substantial alteration. However, in the active state, each of the first and second holographic elements diffracts a first bandwidth light. The first and second holographical elements record a hologram in a switchable holographic material. This material may be formed from a polymer dispersed liquid crystal material.

Claims

1. An apparatus comprising:

a fit pair of holographic optical elements electrically switchable between active and inactive states;

wherein a first holographic optical element of the first pair, when operating in the inactive state, is configured to transmit first bandwidth light substantially unaltered;

wherein a second holographic optical element of the first pair, when operating in the inactive state, is configured to transmit first bandwidth light substantially unaltered;

wherein the first holographic optical element, when operating in the active slate, is configured to diffract first bandwidth light;

wherein the second holographic optical element, when operating in the active state, is configured to diffract first bandwidth light received on a first surface thereof, wherein first bandwidth light received on the first surface thereof and subsequently diffracted by the second holographic optical clement, emerges from the first surface thereof, and;

a quarter wave plate positioned between the first and second holographic optical elements of the first pair.

2. The apparatus of claim 1 further comprising:

a second pair of holographic optical elements electrically switchable between active and inactive states;

a third pair of holographic optical elements electrically switchable between active and inactive states;

wherein a first holographic optical element of the second pair, when operating in the inactive state, is configured to transmit second bandwidth light substantially unaltered;

wherein a second holographic optical element of the second pair, when operating in the inactive state, is configured to transmit second bandwidth light substantially unaltered;

wherein a first holographic optical element of the third pair, when operating in the inactive state, is configured to transmit third bandwidth light substantially unaltered;

wherein a third holographic optical element of the third pair, when operating in the inactive state, is configured to transmit third bandwidth light substantially unaltered;

wherein the second holographic optical element of the second pair, when operating in the active state, is configured to diffract second bandwidth light received on a second surface thereof, and wherein the second bandwidth light received on the second surface thereof and diffracted by the second holographic optical element of the second pair, emerges from the second surface thereof;

wherein the second holographic optical element of the third pair, when operating in the active state, is configured to diffract third bandwidth light received on a third surface thereof, and wherein the third bandwidth light received on the third surface thereof and diffracted by the second holographic optical element of the third pair, emerges from the third surface thereof;

wherein the quarter wave plate is positioned between the first and second holographic optical elements of the second pair, and;

wherein the quarter wave plate is positioned between the first and second holographic optical elements of the third pair.

3. The apparatus of claim 1 wherein the first holographic optical element is formed from polymer dispersed liquid crystal material.

4. The apparatus of claim 1 wherein the second holographic optical element is formed from polymer dispersed liquid crystal material.

5. The apparatus of claim 1 wherein the first and second holographic optical elements are formed from polymer dispersed liquid crystal material.

6. The apparatus of claim 1 wherein the first holographic optical element comprises a thin phase hologram recorded in a holographic recording medium.

7. The apparatus of claim 1 wherein the first holographic optical element comprises a volume phase hologram recorded in a holographic recording medium.

8. The apparatus of claim 1 wherein the second holographic optical element comprises a volume phase hologram recorded in a holographic recording medium.

9. The apparatus of claim 1 wherein the first holographic optical element comprises first and second oppositely facing surfaces, wherein the first surface of the first optical element faces the quarter wave plate positioned between the first and second holographic optical elements, wherein the second surface of the second surface of the first optical element is configured to receive first bandwidth light, and wherein first bandwidth light received at the second surface of the first optical element and subsequently diffracted by the first optical element, emerges from the first surface of the first optical element.

10. The apparatus of claim 1 wherein the first holographic optical element comprises first and second oppositely facing surfaces, wherein the first surface of the first optical element faces the quarter wave plate positioned between the first and second holographic optical elements, wherein the first surface of the second surface of the first optical element is configured to receive first bandwidth light, and wherein first bandwidth light received at the first surface of the first optical element and subsequently diffracted by the first optical element, emerges from the first surface of the first optical element.

11. The apparatus of claim 1 further comprising a control circuit and a voltage source, wherein the control circuit is configured to selectively couple the voltage source to the first and second holographic optical elements, wherein the first and second holographic optical elements operate in the inactive state when coupled to the voltage source, and wherein the first and second holographic optical elements operate in the active state when coupled to the voltage source.

12. The apparatus of claim 1 further comprising an image display, wherein diffracted light transmitted through the first holographic optical element illuminates the image display.

13. The apparatus of claim 1 wherein the first holographic optical element comprises a layer of material that records a hologram and at least one layer of electrically conductive material positioned adjacent the layer of material that records the hologram.

14. The apparatus of claim 1 wherein the first holographic optical element comprises a layer of material that records a hologram and a pair of layers of electrically conductive material, wherein the layer of material that records the hologram is contained between the pair of layers of electrically conductive material.

15. The apparatus of claim 1 wherein the second holographic optical element comprises a layer of material that records a hologram and at least one layer of electrically conductive material positioned adjacent the layer of material that records the hologram.

16. The apparatus of claim 1 wherein the second holographic optical element comprises a layer of material that records a hologram and a pair of layers of electrically conductive material, wherein layer of material that records the hologram is contained between the pair of layers of electrically conductive material.

17. The apparatus of claim 1 wherein the second holographic optical element comprises a layer of material that records a hologram and an array of electrically conductive elements, wherein the array of electrically conductive elements is positioned adjacent the layer of material that records the hologram.

18. The apparatus of claim 2 further comprising a control circuit and a voltage source wherein the control circuit is configured to selectively couple the voltage source to each of the first and second holographic optical elements of the first, second, and third pairs of holographic optical elements wherein each of the first, second, and third pairs of holographic optical elements operate in the inactive state when coupled to the voltage source, and wherein each of the first, second, and third pairs of holographic optical elements operates in the active state when coupled to the voltage source.

19. The apparatus of claim 13 wherein the at least one layer of electrically conductive material comprises indium tin oxide (ITO).

20. The apparatus of claim 13 wherein the at least one layer of electrically conductive material is configured to be selectively coupled to a voltage source, wherein the first holographic optical element operates in the inactive state when the at least one layer of electrically conductive material of the first holographic optical element is coupled to the voltage source, and wherein the first holographic optical element operates in the active state when the at least one layer of electrically conductive material of the first holographic optical element is not coupled to the voltage source.

21. The apparatus of claim 14 wherein each layer of electrically conductive material comprises indium tin oxide (ITO).

22. The apparatus of claim 15 wherein the at least one layer of electrically conductive material comprises indium tin oxide (ITO).

23. The apparatus of claim 16 wherein each layer of electrically conductive material comprises indium tin oxide (ITO).

24. The apparatus of claim 15 wherein the at least one layer of electrically conductive material is configured to be selectively coupled to a voltage source, wherein the second holographic optical element operates in the inactive state when the at least one layer of electrically conductive material of the second holographic optical element is coupled to the voltage source, and wherein the second holographic optical element operates in the active state when the at least one layer of electrically conductive material of the second holographic optical element is not coupled to the voltage source.

25. The apparatus of claim 17 further comprising a control circuit and a voltage source, wherein the control circuit is configured to selectively couple the voltage source to one or more of the electrically conductive elements.

26. The apparatus of claim 17 wherein each electrically conductive element in the array comprises indium tin oxide (ITO).

27. The apparatus of claim 25 wherein the control circuit is configured to couple the voltage to a first set of electrically conductive elements while a second set of electrically conductive elements are decoupled from the voltage source.

28. The apparatus of claim 25 wherein the control circuit selectively couples the voltage source to one or more of the electrically conductive elements in response to the control circuit receiving image signals.

29. An apparatus comprising:

a first pair of holographic optical elements each having a first surface aligned on a common axis so that the fist surfaces face each other;

a quarter wave plate aligned with the first surfaces of the first pair of holographic optical elements and positioned between the first pair of holographic optical elements;

wherein a fast holographic optical element of the first pair is configured to diffract first bandwidth light;

wherein a second holographic optical element of the first pair is configured to diffract first bandwidth light;

wherein the second holographic optical clement is configured to diffract first bandwidth light received on a first surface thereof, wherein first bandwidth light received on the first surface thereof and subsequently diffracted by the second holographic optical element, emerges from the fast surface thereof;

wherein the first holographic optical element is switchable between active and inactive state, wherein the first holographic optical element is configured to transmit first bandwidth light substantially unaltered when operating in the inactive state, and wherein the first holographic optical element is configured to diffract first bandwidth light when operating in the active state, and;

wherein the second holographic optical element is switchable between active and inactive states, wherein the second holographic optical element is configured to transmit first bandwidth light substantially unaltered when operating in the inactive state, and wherein the second holographic optical clement, when operating in the active state, is configured to diffract first bandwidth light received on the first surface thereof wherein first bandwidth light received on the first surface thereof and subsequently diffracted by the second holographic optical element, emerges from the first surface thereof.

30. The apparatus of claim 29 wherein the first holographic optical element is configured to transmit light, other than first bandwidth light, without substantial alteration and wherein the second holographic optical element is configured to transmit light, other than first bandwidth light, without substantial alteration.

31. The apparatus of claim 29 wherein the second holographic optical element is switchable between active and inactive states, wherein the second holographic optical element is configured to transmit first bandwidth light substantially unaltered when operating in the inactive state, and wherein the second holographic optical element, when operating in the active state, is configured to diffract first bandwidth light received on the first surface thereof, wherein first bandwidth light received on the first surface thereof and subsequently diffracted by the second holographic optical element, emerges from the first surface thereof.

32. The apparatus of claim 29 wherein the first holographic optical element is switchable between active and inactive states, wherein the first holographic optical element is configured to transmit first bandwidth light substantially unaltered when operating in the inactive state, and wherein the first holographic optical element is configured to diffract first bandwidth light when operating in the active state.

33. The apparatus of claim 29 further comprising:

a second pair of holographic optical elements electrically switchable between active and inactive states;

a third pair of holographic optical elements electrically switchable between active and inactive states;

wherein a first holographic optical element of the second pair, when operating in the inactive state, is configured to transmit second bandwidth light substantially unaltered;

wherein a second holographic optical element of the second pair, when operating in the inactive state, is configured to diffract second bandwidth light substantially unaltered;

wherein a first holographic optical element of the third pair, when operating in the inactive state, is configured to transmit third bandwidth light substantially unaltered;

wherein a third holographic optical element of the third pair, when operating in the inactive state, is configured to transmit third bandwidth light substantially unaltered;

wherein the second holographic optical clement of the second pair, when operating in the active state, is configured to diffract second bandwidth light received on a second surface thereof, and wherein the second bandwidth light received on the second surface thereof and diffracted by the second holographic optical element of the second pair, emerges from the second surface thereof;

wherein the second holographic optical element of the third pair, when operating in the active state, is configured to diffract third bandwidth light received on a third surface thereof, and wherein the third bandwidth light received on the third surface hereof and diffracted by the second holographic optical element of the third pair, emerges from the third surface thereof;

wherein the quarter wave plate is positioned between the first and second holographic optical elements of the second pair, and;

wherein the quarter wave plate is positioned between the first and second holographic optical elements of the third pair.

34. The apparatus of claim 29 wherein the first holographic optical element is formed from polymer dispersed liquid crystal material.

35. The apparatus of claim 29 wherein the second holographic optical element is formed from polymer:

r dispersed liquid crystal material.

36. The apparatus of claim 29 wherein the first and second holographic optical elements are formed from polymer dispersed liquid crystal material.

37. The apparatus of claim 29 wherein the first holographic optical element comprises a thin phase hologram recorded in a holographic recording medium.

38. The apparatus of claim 29 wherein the first holographic optical clement comprises a volume phase hologram recorded in a holographic recording medium.

39. The apparatus of claim 29 wherein the second holographic optical element comprises a volume phase hologram recorded in a holographic recording medium.

40. The apparatus of claim 29 wherein the first holographic optical element comprises first and second oppositely facing surfaces, wherein the first surface:

of the first optical element faces the quarter wave plate positioned between the first and second holographic optical elements, wherein the second surface of the second surface of the first optical element is configured to receive first bandwidth light, and wherein first bandwidth light received at the second surface of the first optical element and subsequently diffracted by the first optical element;

emerges from the first surface of the first optical element.

41. The apparatus of claim 29 where the first holographic optical element comprises first and second oppositely facing surfaces, wherein the first surface of the first optical element faces the quarter wave plate positioned between the first and second holographic optical elements, wherein the first surface of the second surface of the first optical element is configured to receive first bandwidth light, and wherein first bandwidth light received at the first surface of the first optical element and subsequently diffracted by the first optical element emerges from the first surface of the first optical element.

42. The apparatus of claim 29 further comprising a control circuit and a voltage source, wherein the control circuit is configured to selectively couple the voltage source to the first and second holographic optical elements, wherein the first and second holographic optical elements operate in the inactive state when coupled to the voltage source, and wherein the first and second holographic optical elements operate in the active state when coupled to the voltage source.

43. The apparatus of claim 29 further comprising a control circuit and a voltage source wherein the control circuit is configured to selectively couple the voltage source to each of the first and second holographic optical elements of the first, second, and third pairs of holographic optical elements wherein each of the first, second, and third pairs of holographic optical elements operate in the inactive state when coupled to the voltage source, and wherein each of the first, second, and third pairs of holographic optical elements operates in the active state when coupled to the voltage source.

44. The apparatus of claim 29 wherein the first holographic optical element comprises a layer of material that records a hologram and at least one layer of electrically conductive material positioned adjacent the layer of material that records the hologram.

45. The apparatus of claim 29 wherein the first holographic optical element comprises a layer of material that records a hologram and a pair of layers of electrically conductive material, wherein the layer of material that records the hologram is contained between the pair of layers of electrically conductive material.

46. The apparatus of claim 29 wherein the second holographic optical element comprises a layer of material that records a hologram and at least one layer of electrically conductive material positioned adjacent the layer of material that records the hologram.

47. The apparatus of claim 29 wherein the second holographic optical element comprises a layer of material that records a hologram and a pair of layers of electrically conductive material, wherein layer of material that records the hologram is contained between the pair of layers of ilectrically conductive material.

48. The apparatus of claim 29 wherein the second holographic optical element comprises a layer of material that records a hologram and an array of electrically conductive elements, wherein the array of electrically conductive elements is positioned adjacent the layer of material that records the hologram.

49. The apparatus of claim 29 further comprising an image display, wherein diffracted light transmitted through the first holographic optical element illuminates the image display.

50. The apparatus of claim 30 further comprising a quarter wave plate aligned with the first surfaces of the first pair of holographic optical elements and positioned between the first pair of holographic optical elements.

51. The apparatus of claim 44 wherein each electrically conductive element in the array comprises indium tin oxide (ITO).

52. The apparatus of claim 45 wherein the at least one layer of electrically conductive material comprises indium tin oxide (ITO).

53. The apparatus of claim 46 wherein each layer of electrically conductive material comprises indium tin oxide (ITO).

54. The apparatus of claim 46 wherein the at least one layer of electrically conductive material is configured to be selectively coupled to a voltage source, wherein the first holographic optical element operates in the inactive state when the at least one layer of electrically conductive material of the first holographic optical element is coupled to the voltage source, and wherein the first holographic optical element operates in the active state when the at least one layer of electrically conductive material of the first holographic optical element is not coupled to the voltage source.

55. The apparatus of claim 46 wherein the at least one layer of electrically conductive material is configured to be selectively coupled to a voltage source, wherein the second holographic optical element operates in the inactive state when the at least one layer of electrically conductive material of the second holographic optical element is coupled to the voltage source, and wherein the second holographic optical element operates in the active state when the at least one layer of electrically conductive material of the second holographic optical element is not coupled to the voltage source.

56. The apparatus of claim 47 wherein the at least one layer of electrically conductive material comprises indium tin oxide (ITO).

57. The apparatus of claim 48 further comprising a control circuit and a voltage source, wherein the control circuit is configured to selectively couple the voltage source to one or more of the electrically conductive elements.

58. The apparatus of claim 48 wherein each layer of electrically conductive material comprises indium tin oxide (ITO).

59. The apparatus of claim 57 wherein the control circuit is configured to couple the voltage to a first set of electrically conductive elements while a second set of electrically conductive elements are decoupled from the voltage source.

60. The apparatus of claim 57 wherein the control circuit selectively couples the voltage source to one or more of the electrically conductive elements in response to the control circuit receiving image signals.

61. A method comprising:

diffracting a first bandwidth light incident on a first optical element of a first pair of optical elements to produce a first diffracted light;

passing the first diffracted light through a quarter wave plate to produce a polarized light;

diffracting the polarized light using a second optical element of the first pair of optical elements to produce a second diffracted light;

passing the second diffracted light through the quarter wave plate, and;

transmitting the second diffracted light through the first optical element without substantial alteration after the second diffracted light passes through the quarter wave plate;

wherein the quarter wave plate is positioned between the first and second optical elements.

62. The method of claim 61 further comprising:

activating the first and second optical elements prior to the first optical element diffracting the first bandwidth light incident thereon and prior to the second optical element diffracting the polarized light, and;

deactivating the first and second optical elements after the first optical element diffracts the first bandwidth light incident thereon and after to the second optical element diffracts the polarized light, and;

transmitting first bandwidth light through the first optical element without substantial alteration while the first optical element is deactivated thereby producing a first transmitted light;

passing the first transmitted light through the quarter wave plate to produce a second polarized light, and;

transmitting the second polarized light through the second optical element without substantial alteration while the second optical element is deactivated.

63. The method of claim 61 further comprising:

the first optical element receiving the first bandwidth light prior to the first optical element diffracting the first bandwidth light, wherein the first bandwidth light is received on a surface of the first optical element at a first angle measured with respect to an optical axis, wherein the optical axis is normal to the surface of the first optical element, and;

the second diffracted light transmitted through the first optical element emerging from the surface at a second angle measured with respect to the optical axis;

wherein the first angle is greater than the second angle.

64. The method of claim 62 wherein activating the first and second optical elements comprises coupling the first and second optical elements to a voltage source, and wherein deactivating the first and second optical elements comprises decoupling the first and second optical elements to a voltage source.

65. The method of claim 64 further comprising illuminating an image display with the second diffracted light transmitted through the first optical element.

66. The method of claim 64 further comprising

activating first and second optical elements of a second pair of optical elements after deactivating the first and second optical elements of the first pair of optical elements;

diffracting a second bandwidth light incident on a first optical element of the second pair of optical elements to produce a third diffracted light;

passing the third diffracted light through a quarter wave plate to produce a second polarized light;

diffracting the second polarized light using the second optical element of the second pair of optical elements to produce a fourth diffracted light;

passing the fourth diffracted light through the quarter wave plate, and;

transmitting the fourth diffracted light through the first optical element of the second pair of optical elements without substantial alteration after the fourth diffracted light passes through the quarter wave plate;

wherein the quarter wave plate is positioned between the first and second optical elements of the second pair of optical elements.