Light guide optical device

• US 20050180687A1
• Filed: 03/19/2003
• Published: 08/18/2005
• Est. Priority Date: 03/21/2002
• Status: Active Grant

• Current Assignee: Lumus Ltd.
• Original Assignee: Lumus Ltd.
• Inventors: Amitai, Yaakov
• Granted Patent: US 7,457,040 B2
• Time in Patent Office: Days
• US Class Current: 385/31
• CPC Class Codes: G02B 2006/0098 for scanning
• CPC Class Codes: G02B 2027/0114 comprising dichroic elements
• CPC Class Codes: G02B 2027/012 comprising devices for attenuating parasitic image effects
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 2027/0132 comprising binocular systems
• CPC Class Codes: G02B 2027/0136 with a single image source for both eyes
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/022 Viewing apparatus G02B27/04, G02B27/06, G02B27/08 take precedence
• CPC Class Codes: G02B 27/1073 characterized by manufacturing or alignment methods
• CPC Class Codes: G02B 27/108 for sampling a portion of a beam or combining a small beam in a larger one, e.g. wherein the area ratio or power ratio of the divided beams significantly differs from unity, without spectral selectivity
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/148 including stacked surfaces having at least one double-pass partially reflecting surface
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 30/26 of the autostereoscopic type
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0028 : Light guide, e.g. taper
• CPC Class Codes: G02B 6/003 : Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0055 : Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0056 : for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements

Abstract

There is provided an optical device including a light-transmitting substrate having at least two major surfaces and edges, optical means for coupling light into the substrate by total internal reflection and at least one partially reflecting surface located win the substrate.

Claims

1. An optical device, comprising:

a light-transmitting substrate having at least two major surfaces parallel to each other and edges;

optical means for coupling light waves located in a given field-of-view into said substrate by total internal reflection, and

at least one partially reflecting surface located in said the substrate-., said surface being non-parallel to said major surfaces of the substrate,

wherein waves located in said field-of-view arrive at both sides of said partially reflecting surface.

2. The optical device according to claim 1, wherein said optical means for coupling light into said substrate is disposed at an angle to said major surfaces to cause at least part of the rays of said coupled light to intersect said partially reflecting surface at least twice with two different incident angles.

3. The optical device according to claim 1, wherein rays of said coupled light impinge on one side of the surface at a first angle of incidence and rays of said coupled light impinge on a second side of said surface at a second smaller angle of incidence.

4. The optical device according to claim 1, wherein said partially reflecting surface has a small reflection for one part of the angular spectrum and a larger reflection for other parts of the angular spectrum.

5. The optical device according to claim 4, wherein said partly reflecting surface has a low reflectance at high incident angles and a high reflectance at low incident angles.

6. The optical device according to claim 3, wherein said partly reflecting surface has a small reflection for one of said incident angles and a significantly larger reflection for the second of said incident angles.

7. The optical device according to claim 3, wherein said one incident angle having small reflectance is larger than said second incident angle.

8. The optical device according to claim 1, wherein there is provided an array of two or more partially reflecting surfaces characterized in that said partially reflecting surfaces are parallel to each other and are non-parallel to any of the edges of said major surfaces of the substrate.

9. The optical device according to claim 1, wherein said optical means is a wave-reflecting surface located in said substrate.

10. The optical device according to claim 1, wherein said at least one partially reflecting surface couples the light trapped by total internal reflection out of said substrate.

11. The optical device according to claim 10, wherein said optical means for coupling light into said substrate is disposed at an angle to said major surfaces to cause at least part of said coupled light to intersect said partly reflecting surface at least twice with two different incident angles, before being coupled out of said substrate.

12. The optical device according to claim 1, further comprising means for producing output light waves from input light waves, wherein said input light waves and output light waves are located on the same side of said substrate.

13. The optical device according to claim 1, further comprising means for producing output light waves from input light waves, wherein said input light waves are located on one side of said substrate and said output light waves are located on another side of said substrate.

14. The optical device according to claim 1, further comprising means for producing output light waves from input light waves, wherein input light waves are coupled into said substrate through one of its edges.

15. The optical device according to claim 1, wherein the reflectance of said at least one partially reflecting surface is selected to control the field of view.

16. The optical device according to claim 1, wherein the reflectance of each of said partially reflecting surfaces is non-uniform across the reflecting surfaces producing a field of view having a selected brightness profile.

17. The optical device according to claim 1, wherein the distances between said partially reflecting surfaces is selected to control the brightness across the field of view.

18. The optical device according to claim 1, wherein said partially reflecting surface having a coating for P-polarized light.

19. The optical device according to claim 1, wherein the reflectance of partially reflecting surface having a coating for an S-polarized light.

20. The optical device according to claim 1, wherein the reflectance of said partially reflecting surface having a coating for an unpolarized light.

21. The optical;

device according to claim 1, further comprising a second set of one or more reflecting or partially reflecting surfaces located in said substrate said second set of partially reflecting surfaces being parallel to each other and not being parallel to said at least one partially reflecting surface.

22. The optical device according to claim 21, wherein said second set of reflecting or partially reflecting surfaces changes the direction of propagation of the light coupled in said substrate by total internal reflection.

23. The optical device according to claim 21, wherein the reflectance of said second plurality of partially reflecting surfaces produces a field of view having a uniform brightness profile.

24. The optical device according to claim 21, wherein the reflectance of said second plurality of partially reflecting surfaces is selected to control the brightness across the field of view.

25. The optical device according to claim 1, further comprising at least one pair of reflecting surfaces carried by said substrate said pair of reflecting surfaces being parallel to each other and being part of the edges of said substrate.

26. The optical device according to claim 25, wherein said at least one pair of reflecting surfaces changes the direction of propagation of the light coupled in said substrate by total internal reflection and then reflecting it back to its original direction.

27. The optical device according to claim 25, wherein the location and orientation of said at least one pair of reflecting surfaces is selected to control the field of view for a given input aperture.

28. The optical device according to claim 25, wherein the location and orientation of said at least one pair of reflecting surfaces is selected to control the input aperture for a given field of view.

29. The optical device according to claim 1, further comprising at least two different substrates combined together.

30. The optical device according to claim 29, wherein the location and orientation of said at least two substrates is selected to control the input aperture for a given field of view.

31. The optical device according to claim 29, wherein the reflectance of the partially reflecting surfaces which are located in said at least two substrates is selected to control the brightness across the field of view.

32. The optical device according to claim 1, further comprising a display light source.

33. The optical device according to claim 1, wherein the said display light source is a liquid crystal display (LCD).

34. The optical device according to claim 33, wherein a diffuser is located between the light source and the liquid-crystal of said LCD is an angular selective diffuser.

35. The optical device according to claim 33, wherein the angular disposition of said diffuser is selected to control the brightness across the field of view.

36. The optical device according to claim 1, wherein said display light source is an organic light emitting diode display (OLED), having a divergence angle.

37. The optical device according to claim 36, wherein the divergence angle of said diode is selected to control the brightness across the field of view.

38. The optical device according to claim 23, further comprising an array of micro-lenses laterally aligned with said display light source.

39. The optical device according to claim 27, wherein the focal length and location of said micro-lenses is selected to control the brightness across the field of view.

40. The optical device according to claim 1, wherein said substrate is partially transparent, for allowing see-through operation.

41. The optical device according to claim 1, further comprising an opaque surface located on or in said substrate, so as to block the entrance of light traversing the substrate from an external scene.

42. The optical device according to claim 1, further comprising a variable transmittance surface located so as to attenuate the entrance of light traversing the substrate for controlling the brightness of light passing through said device from an external scene.

43. The optical device according to claim 42, wherein the transmittance of said variable transmittance surface is automatically controlled according to the brightness of light directed to traverse the substrate.

44. The optical device according to claim 1, wherein said at least one partially reflecting surface reflects trapped light waves into a direction for reaching one eye of an observer.

45. The optical device according to claim 1, wherein the said at least one partially reflecting surface reflects trapped waves into a direction for reaching both eves of an observer.

46. The optical device according to claim 45, further comprising a plurality of display light sources.

47. The optical device according to claim 46, wherein the images from said plurality of display light sources differ from each other.

48. The optical device according to claim 1, wherein said device couples the light from the external scene into said substrate.

49. The optical device according to claim 1, further comprising a stars light amplifier.

50. The optical device according to claim 48, in which the device is configured to be disposed at the side of the observer'"'"'s head, with the objective located to the back and the eve-piece to the front.

51. The optical device according to claim 1, wherein said at device is mounted in an eve-glasses frame.

52. The optical device according to claim 1, wherein said device is located in a mobile communication device.

53. The optical device according to claim 1, wherein said at least one partially reflecting surface reflects trapped light waves into a direction for illuminating an object.

54. The optical device according to claim 53, wherein said object is a liquid crystal display.

55. An optical device, comprising:

a light-transmitting substrate having at least two major surfaces parallel to each other and edges;

at least one partially reflecting surface located in said substrate which is non-parallel to said major surfaces of the substrate

characterized by at least two display light sources, and

optical means for coupling light from said light sources into said substrate by internal reflection.

56. The optical device according to claim 55, wherein said at least one partially reflecting surface couples the light trapped by internal reflection out of said substrate.

57. The optical device according to claim 56, wherein said at least one partially reflecting surface reflects trapped waves into a direction calculated to reach both eyes of an observer.

58. The optical device according to claim 55, wherein the images from said display sources are identical.

59. The optical device according to claim 55, wherein the images from said display sources are different.

60. The optical device according to claim 55, wherein the images from said plurality of display light sources produce a three-dimensional image.

61. The optical device according to claim 56, wherein the reflectance of said at least one partially reflecting surface produces a field of view having uniform brightness across the FOV.

62. The optical device according to claim 56, wherein the reflectance of said at least one partially reflecting surface produces a field of view having a predefined brightness.

63. The optical device according to claim 55, wherein at least one of said display light sources is a liquid crystal display (LCD).

64. The optical device according to claim 55, wherein at least one of said display light sources is an organic light emitting diode display (OLED).

65. The optical device according to claim 55, wherein said substrate is partially transparent, to enable see-through operation.

66. The optical device according to claim 55, further comprising an opaque surface located on or in said substrate, so as to block the entrance of light traversing the substrate from an external scene.

67. The optical device according to claim 55, further comprising a variable transmittance surface located so as to attenuate the entrance of light traversing the substrate, for controlling the brightness of light passing through said device from an external scene.

68. The optical device according to claim 67, wherein the transmittance of said variable transmittance surface is determined according to the brightness of light directed to traverse the substrate.

69. An optical device for partially reflecting a first set of light waves having a given polarization state and located within a given optical spectrum and within a first angular spectrum, and transmitting a second set of light waves having the same given polarization state and located within the same given optical spectrum and within a second angular spectrum, comprising:

a first light-transmitting substrate having a surface, and

a dichroic coating disposed on said surface,

characterized in that angles located within said first angular spectrum are smaller than angles located within said second angular spectrum and that the reflectivity by the coated surface of said first set of light waves is higher than the reflectivity by the coated surface of said second set of light waves.

70. The optical device according to claim 69, further comprising a second light-transmitting substrate optically coupled to the first light-transmitting substrate at said coated surface.

71. The optical device according to claim 69, wherein said polarization state is the P-polarization.

72. The optical device according to claim 69, wherein said polarization state is a combination of the S and the P polarizations.

73. The optical device according to claim 69, wherein the reflectance of said first set of light waves changes monotonically with increasing incident angles at said surface.

74. The optical device according to claim 72, wherein the reflectance of said first set of light waves decreases monotonically with increasing incident angles at said surface.

75. The optical device according to claim 73, wherein the reflectance of said first set of light waves increases monotonically with increasing incident angles at said surface.

76. The optical device according to claim 69, wherein said optical spectrum is located within the visual spectrum.

77. The optical device according to claim 69, wherein said optical spectrum is located within the region between 460 nm and 640 nm.

78. The optical device according to claim 69, wherein said first angular spectrum is located within the region between 15°

and 40°

.

79. The optical device according to claim 69, wherein said second angular spectrum is located within the region between 50°

and 80°

.

80. The optical device according to claim 69, wherein a specific minimal reflectance is set for said first angular spectrum.

81. The optical device according to claim 80, wherein the reflectivity by said coated surface of said first set of light waves is higher than said specific minimal reflectance.

82. The optical device according to claim 69, wherein a specific maximal reflectance is set for said second angular spectrum.

83. The optical device according to claim 82, wherein the reflectivity by said coated surface of said second set of light waves is lower than said specific maximal reflectance.

84. The optical device according to claim 80, wherein the reflectivity of said specific minimal reflectance is higher than 20%.

85. The optical device according to claim 82, wherein the reflectivity of said specific maximal reflectance is lower than 10%.

86. An optical device, comprising:

a light-transmitting substrate having at least two major surfaces parallel to each other and edges;

optical means for coupling rays of light into said substrate by total internal reflection, and

at least one partially reflecting surface located in said substrate which surface is non-parallel to said major surfaces of the substrate,

characterized in that said optical means for coupling light into said substrate is oriented at an angle to said major surfaces, to cause rays to arrive at both sides of said partially reflecting surface.

87. The optical device as claimed in claim 86, wherein said optical means for coupling light into said substrate is disposed at an angle to said major surfaces to cause at least part of the coupled light to intersect said partly reflecting surface at least twice with two different incident angles.

88. An optical device, comprising:

a light-transmitting substrate having at least two major surfaces parallel to each other and edges;

optical means for coupling rays of light into said substrate by total internal reflection, and

at least one partially reflecting surface located in said substrate which surface is non-parallel to said major surfaces of the substrate,

characterized in that said optical means for coupling light into the substrate is disposed at an angle to said major surfaces, causing rays of the coupled light having same off-axis angle inside said substrate, to intersect said partly reflecting surface with two different incident angles.

89. An optical device, comprising:

a light-transmitting substrate having at least two major surfaces parallel to each other and edges;

at least one partially reflecting surface located in said substrate, which surface is non-parallel to said major surfaces of the substrate, and

optical means for coupling into said substrate by total internal reflection, rays of light having the same off-axis angle inside said substrate, which rays of light intersect said partially reflected surface with two different incident angles.

90. An optical device, comprising:

a light-transmitting substrate having at least two major surfaces parallel to each other and edges;

optical means for coupling rays of light into said substrate by total internal reflection, and

at least one partially planar reflecting surface located in said substrate which planar reflecting surface is non-parallel to said major surfaces of the substrate.

91. An optical device, comprising:

a light-transmitting substrate having at least two major surfaces parallel to each other and edges;

optical means for coupling rays of light into said substrate by total internal reflection, and

at least one partially reflecting surface located in said substrate, which surface is non-parallel to said major surfaces of the substrate,

characterized in that said optical means for coupling light into the substrate is disposed at an angle to the major surfaces to cause rays of the coupled light having the same off-axis angle inside the substrate to intersect said partially reflecting surface with two different incident angles.