Compact two-plane optical device

• US 6,833,955 B2
• Filed: 10/09/2001
• Issued: 12/21/2004
• Est. Priority Date: 10/09/2001
• Status: Expired due to Fees

• Current Assignee: Mirage Innovations Limited
• Original Assignee: Planop-Planar Optics, Ltd.
• Inventors: Niv, Yehuda
• Primary Examiner(s): Nguyen, Thong
• Assistant Examiner(s): Lavarias, Arnel C.
• Application Number:
  US09/971,906
• Publication Number:
  US 20030067685A1
• Time in Patent Office: 1,169 Days
• Field of Search: 359/566, 359/300, 359/15, 359/558, 359/569, 359/571, 359/572, 359/573, 359/13, 359/34, 359/19, 359/630, 359/633, 345/7, 345/8, 345/9
• US Class Current: 359/566
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide

Abstract

An optical device for enlarging an eye box, the optical device comprising: (a) a first optical expander being carried by, or formed in, a first light-transmissive substrate engaging a first plane; and (b) a second optical expander being carried by, or formed in, a second light-transmissive substrate engaging a second plane being spaced apart from the first plane. The first and the second optical expanders designed and configured such that light passing through the first optical expander is expanded in a first dimension, enters the second light-transmissive substrate through the second optical expander, and exits from the second light-transmissive substrate, expanded in a second dimension, hence enlarging an eye box of the optical device in both the first and the second dimensions.

Claims

1. An optical device for enlarging an eye box, the optical device comprising:

(a) a first optical expander being carried by, or formed in, a first light-transmissive substrate engaging a first plane; and

(b) a second optical expander being carried by, or formed in, a second light-transmissive substrate engaging a second plane being spaced apart from said first plane;

said first and said second optical expanders being designed and configured such that;

(i) at least a first portion of light entering said first light-transmissive substrate experiences a substantially total internal reflection, diffracted by said first optical expander and exits from said first light-transmissive substrate expanded in a first dimension; and

(ii) at least a second portion of said first portion of light enters said second light-transmissive substrate, experiences a substantially total internal reflection, diffracted by said second optical expander and exits from said second light-transmissive substrate expanded in a second dimension;

such that light rays of said light entering said first light-transmissive substrate are multiplied into a plurality of substantially parallel outgoing rays exiting said second light-transmissive substrate, hence enlarging an eye box of the optical device in both said first and said second dimensions.

2. The optical device of claim 1, wherein said first and second planes are substantially parallel.

3. The optical device of claim 1, wherein said first and second dimensions are substantially orthogonal.

4. The optical device of claim 2, wherein said first and second dimensions are substantially orthogonal.

5. The optical device of claim 1, further comprising an input light source for producing said light.

6. The optical device of claim 5, wherein said input light source comprises an input display source, hence said light constitutes an image.

7. The optical device of claim 1, wherein said first and second optical expanders substantially parallel one another and at least partially overlap in a direction substantially perpendicular both thereto.

8. The optical device of claim 6, wherein said first optical expander is configured and designed so as to transform spherical waves emanating from said input display source into plane waves, to at least partially diffract said plane waves, and to reflect said plane waves within said first light-transmissive substrate, hence to expand said image in said first dimension.

9. The optical device of claim 8, wherein said second optical expander is configured and designed so as to at least partially diffract at least a portion of light rays exiting said first light-transmissive substrate, hence to expand said image in said second dimension, and to couple said light rays out of said second light-transmissive substrate in a direction of an eye of a user.

10. The optical device of claim 1, further comprising:

(c) an optical trapping element being carried by, or formed in, said second light-transmissive substrate and being laterally displaced from said second optical expander.

11. The optical device of claim 10, wherein said optical trapping element is configured and designed so as to trap at least a portion of light rays exiting said first light-transmissive substrate, inside said second light-transmissive substrate by substantially total internal reflection, hence to propagate said plurality of light rays in a direction of said second optical expander.

12. The optical device of claim 11, wherein said second optical expander is configured and designed so as to at least partially diffract said plurality of light rays, propagated through said second light-transmissive substrate, hence to expand said image in said second dimension, and to couple said plurality of light rays out of said second light-transmissive substrate in a direction of an eye of a user.

13. The optical device of claim 1, wherein each of said first and said second optical expanders is embodied in said light-transmissive substrates by recording an interference pattern of two mutually coherent optical waves.

14. The optical device of claim 13, wherein said interference pattern comprise linear diffraction gratings.

15. The optical device of claim 14, wherein said linear diffraction gratings of said second optical expander is substantially orthogonal to said linear diffraction gratings of said first optical expander.

16. The optical device of claim 14, wherein said linear diffraction gratings of said first and second optical expanders are each independently selected from the group consisting of reflection linear diffraction gratings and transmission linear diffraction gratings.

17. The optical device of claim 13, wherein said recording is effected by a procedure selected from a group consisting of computer-generated masks, lithography, embossing, etching and direct writing.

18. The optical device of claim 10, wherein said optical trapping element, said first optical expander and said second optical expander are each independently embodied in said light-transmissive substrates by recording an interference pattern of two mutually coherent optical waves.

19. The optical device of claim 18, wherein said interference pattern comprise linear diffraction gratings.

20. The optical device of claim 19, wherein said linear diffraction gratings of said optical trapping element is substantially orthogonal to said linear diffraction gratings of said first optical expander.

21. The optical device of claim 19, wherein said linear diffraction gratings are each independently selected from the group consisting of reflection linear diffraction gratings and transmission linear diffraction gratings.

22. The optical device of claim 18, wherein said recording is effected by a procedure selected from a group consisting of computer-generated masks, lithography, embossing, etching and direct writing.

23. The optical device of claim 19, wherein said linear diffraction gratings of said optical trapping element is substantially parallel to said linear diffraction gratings of said second optical expander.

24. The optical device of claim 19, wherein said linear diffraction gratings of said second optical expander and said optical trapping element are with equal periodicity.

25. The optical device of claim 1, wherein each of said first and second light-transmissive substrates comprises a first surface and a second surface.

26. The optical device of claim 25, wherein said first optical expander is embodied in said first surface of said first light-transmissive substrate.

27. The optical device of claim 25, wherein said first optical expander is embodied in said second surface of said first light-transmissive substrate.

28. The optical device of claim 5, further comprising a collimator for collimating said light produced by said input light source.

29. The optical device of claim 28, wherein said collimator comprises a converging lens.

30. The optical device of claim 28, wherein said collimator comprises a diffractive optical element carried by, or formed in, said first light-transmissive substrate.

31. The optical device of claim 1, further comprising at least one optical element for redirecting light rays, positioned so as to reduce an overall size of the optical device.

32. The optical device of claim 31, wherein said at least one optical element is a 45 degrees mirror.

33. The optical device of claim 1, wherein each of said first optical expander and said second optical expander has a predetermined diffraction efficiency.

34. The optical device of claim 33, wherein said predetermined diffraction efficiency varies locally for achieving an output having substantially uniform light intensities.

35. The optical device of claim 33, wherein said predetermined diffraction efficiency varies locally for achieving an output having predefined intensities.

36. The optical device of claim 10, wherein said optical trapping element has a predetermined diffraction efficiency.

37. The optical device of claim 36, wherein said predetermined diffraction efficiency varies locally for achieving an output having substantially uniform light intensities.

38. The optical device of claim 36, wherein said predetermined diffraction efficiency varies locally for achieving an output having predefined intensities.

39. The optical device of claim 1, wherein said first and said second optical expanders are each independently a plurality of linearly stretched mini-prisms, carried by a variable light transmissive surface.

40. The optical device of claim 10, wherein said optical trapping element is a plurality of linearly stretched mini-prisms.

41. The optical device of claim 1, wherein said first light-transmissive substrate and said second light-transmissive substrate are of thickness ranging between about 0.5 mm and about 5 mm.

42. The optical device of claim 1, wherein said first light-transmissive substrate and said second light-transmissive substrate are each independently selected from the group consisting of glass and transparent plastic.

43. A method of enlarging an eye box, the method comprising:

(a) expanding inputted light rays in a first dimension by propagating said light rays in a first light-transmissive substrate via a substantially total internal reflection and diffracting said light rays out of said first light-transmissive substrate using a first optical expander engaging a first plane; and

(b) expanding said inputted light rays in a second dimension by propagating said light rays in a second light-transmissive substrate via a substantially total internal reflection and diffracting said light rays out of said second light-transmissive substrate using a second optical expander, in a manner such that said inputted light rays are multiplied into a plurality of substantially parallel outgoing rays exiting said second light-transmissive substrate, said second light-transmissive substrate engaging a second plane being spaced apart from said first plane;

hence enlarging the eye box in both said first and said second dimensions.

44. The method of claim 43, wherein said first and second planes are substantially parallel.

45. The method of claim 43, wherein said first and second dimensions are substantially orthogonal.

46. The optical device of claim 44, wherein said first and second dimensions are substantially orthogonal.

47. The method of claim 43, wherein said inputted light rays constitutes an image.

48. The method of claim 43, wherein said first and second optical expanders substantially parallel one another and at least partially overlap in a direction substantially perpendicular both thereto.

49. The method of claim 43, wherein said expanding in said first dimension and said second dimension comprises at least partially diffracting said inputted light rays.

50. The method of claim 49, wherein said expanding in said first dimension further comprises reflecting said inputted light rays within a first light-transmissive substrate, by substantially total reflection determined by said first optical expander.

51. The method of claim 50, wherein said expanding in said second dimension further comprises reflecting said light rays within a second light-transmissive substrate, by substantially total reflection determined by said second optical expander.

52. The method of claim 43, further comprising prior to step (b):

passing said light rays through an optical trapping element engaging said second plane and being laterally displaced from said second optical expander thereby propagating said light rays through a light guide in a direction of said second optical expander.

53. The method of claim 52, wherein said light guide is a second light-transmissive substrate enabling said inputted light rays to propagate therethrough by substantially total internal reflection determined by said optical trapping element.

54. The method of claim 52, wherein said expanding in said second dimension comprises at least partially diffracting said inputted light rays propagated through said light guide.

55. The method of claim 54, wherein said expanding in said second dimension further comprises reflecting said inputted light rays within said light guide, by substantially total reflection determined by said second optical expander.

56. The method of claim 51, wherein each of said first and said second optical expanders is respectively embodied in said first and said second light-transmissive substrates by recording an interference pattern of two mutually coherent optical waves.

57. The method of claim 56, wherein said interference pattern comprise a linear diffraction gratings.

58. The method of claim 57, wherein said linear diffraction gratings of said second optical expander is substantially orthogonal to said linear diffraction gratings of said first optical expander.

59. The method of claim 57, wherein said linear diffraction gratings of said first and said second optical expanders are each independently selected from the group consisting of reflection linear diffraction gratings and transmission linear diffraction gratings.

60. The method of claim 56, wherein said recording is effected by a procedure selected from a group consisting of computer-generated masks, lithography, embossing, etching and direct writing.

61. The method of claim 52, wherein said optical trapping element, said first optical expander and said second optical expander are each independently embodied in said light-transmissive substrates by recording an interference pattern of two mutually coherent optical waves.

62. The method of claim 61, wherein said interference pattern comprise linear diffraction gratings.

63. The method of claim 62, wherein said linear diffraction gratings of said optical trapping element is substantially orthogonal to said linear diffraction gratings of said first optical expander.

64. The method of claim 62, wherein said linear diffraction gratings are each independently selected from the group consisting of reflection linear diffraction gratings and transmission linear diffraction gratings.

65. The method of claim 61, wherein said recording is effected by a procedure selected from a group consisting of computer-generated masks, lithography, embossing, etching and direct writing.

66. The optical device of claim 62, wherein said linear diffraction gratings of said optical trapping element is substantially parallel to said linear diffraction gratings of said second optical expander.

67. The method of claim 62, wherein said linear diffraction gratings of said second optical expander and said optical trapping element are with equal periodicity.

68. The method of claim 50, wherein said first light-transmissive substrate comprises a first surface and a second surface.

69. The method of claim 68, wherein said first optical expander is embodied in said first surface of said first light-transmissive substrate.

70. The method of claim 68, wherein said first optical expander is embodied in said second surface of said first light-transmissive substrate.

71. The method of claim 43, further comprising collimating said inputted light.

72. The method of claim 71, wherein said collimating is done by a converging lens.

73. The method of claim 71, wherein said collimating is done by a diffractive optical element.

74. The method of claim 43, further comprising redirecting said inputted light, so as to reduce a distance between said first plane and an input light source producing said inputted light.

75. The method of claim 74, wherein said redirecting is done by a 45 degrees mirror.

76. The method of claim 43, wherein each of said, first and said second optical expanders has a predetermined diffraction efficiency.

77. The method of claim 76, wherein said predetermined diffraction efficiency varies locally for achieving an output having substantially uniform light intensities.

78. The method of claim 76, wherein said predetermined diffraction efficiency varies locally for achieving an output having predefined intensities.

79. The optical device of claim 52, wherein said optical trapping element has a predetermined diffraction efficiency.

80. The optical device of claim 79, wherein said predetermined diffraction efficiency varies locally for achieving an output having substantially uniform light intensities.

81. The optical device of claim 79, wherein said predetermined diffraction efficiency varies locally for achieving an output having predefined intensities.

82. The method of claim 43, wherein said first and said second optical expanders are each independently a plurality of linearly stretched mini-prisms, carried by a variable light transmissive surface.

83. The method of claim 52, wherein said optical trapping element is a plurality of linearly stretched mini-prisms.

84. The method of claim 50, wherein said first light-transmissive substrate is of thickness ranging between about 0.5 mm and about 5 mm.

85. The method of claim 53, wherein said second light-transmissive substrate is of thickness ranging between about 0.5 mm and about 5 mm.

86. The method of claim 50, wherein said first light-transmissive substrate is selected from the group consisting of glass and transparent plastic.

87. The method of claim 53, wherein said second light-transmissive substrate is selected from the group consisting of glass and transparent plastic.

88. A method of manufacturing an optical device, for enlarging an eye box, the method comprising:

(a) positioning a first light-transmissive substrate having a first optical expander carried thereby, or formed therein in a first plane; and

(b) positioning a second light-transmissive substrate having a second optical expander carried thereby, or formed therein,

said first and said second optical expanders being designed and configured such that;

(i) at least a first portion of light entering said first light-transmissive substrate experiences a substantially total internal reflection, diffracted by said first optical expander and exits from said first light-transmissive substrate expanded in a first dimension; and

(ii) at least a second portion of said first portion of light enters said second light-transmissive substrate, experiences a substantially total internal reflection, diffracted by said second optical expander and exits from said second light-transmissive substrate expanded in a second dimension;

such that light rays of said light entering said first light-transmissive substrate are multiplied into a plurality of substantially parallel outgoing rays exiting said second light-transmissive substrate.

89. The method of claim 88, wherein said first and second planes are substantially parallel.

90. The method of claim 88, wherein said first and second dimensions are substantially orthogonal.

91. The optical device of claim 89, wherein said first and second dimensions are substantially orthogonal.

92. The method of claim 88, further comprising positioning an input light source for producing said light.

93. The method of claim 92, wherein said input light source comprises an input display source, hence said light constitutes an image.

94. The method of claim 88, wherein said first and second optical expanders substantially parallel one another and at least partially overlap in a direction substantially perpendicular both thereto.

95. The method of claim 93, wherein said first optical expander is designed and configured so as to transform spherical waves emanating from said input display source into plane waves, to at least partially diffract said plane waves, and to reflect said plane waves within said first light-transmissive substrate, hence to expand said image in said first dimension.

96. The method of claim 95, wherein said second optical expander is configured and designed so as to at least partially diffract at least a portion of light rays exiting said first light-transmissive substrate, hence to expand said image in said second dimension, and to couple said light rays out of said second light-transmissive substrate in a direction of an eye of a user.

97. The method of claim 88, further comprising:

(c) providing an optical trapping element being carried by, or formed in, said second light-transmissive substrate and being laterally displaced from said second optical expander.

98. The method of claim 97, wherein said optical trapping element is configured and designed so as to trap at least a portion of light rays exiting said first light-transmissive substrate, inside said second light-transmissive substrate by substantially total internal reflection, hence to propagate said plurality of light rays in a direction of said second optical expander.

99. The method of claim 98, wherein said second optical expander is configured and designed so as to at least partially diffract said plurality of light rays, propagated through said second light-transmissive substrate, hence to expand said image in said second dimension, and to couple said plurality of light rays out of said second light-transmissive substrate in a direction of an eye of a user.

100. The method of claim 88, wherein each of said first and said second optical expanders is embodied in said light-transmissive substrates by recording an interference pattern of two mutually coherent optical waves.

101. The method of claim 100, wherein said interference pattern comprise linear diffraction gratings.

102. The method of claim 101, wherein said linear diffraction gratings of said second optical expander is substantially orthogonal to said linear diffraction gratings of said first optical expander.

103. The method of claim 101, wherein said linear diffraction gratings of said first and second optical expanders are each independently selected from the group consisting of reflection linear diffraction gratings and transmission linear diffraction gratings.

104. The method of claim 100, wherein said recording is effected by a procedure selected from a group consisting of computer-generated masks, lithography, embossing, etching and direct writing.

105. The method of claim 97, wherein said optical trapping element, said first optical expander and said second optical expander are each independently embodied in said light-transmissive substrates by recording an interference pattern of two mutually coherent optical waves.

106. The method of claim 105, wherein said interference pattern comprise linear diffraction gratings.

107. The method of claim 106, wherein said linear diffraction gratings of said optical trapping element is substantially orthogonal to said linear diffraction gratings of said first optical expander.

108. The method of claim 106, wherein said linear diffraction gratings are each independently selected from the group consisting of reflection linear diffraction gratings and transmission linear diffraction gratings.

109. The method of claim 105, wherein said recording is effected by a procedure selected from a group consisting of computer-generated masks, lithography, embossing, etching and direct writing.

110. The method of claim 106, wherein said linear diffraction gratings of said optical trapping element is substantially parallel to said linear diffraction gratings of said second optical expander.

111. The method of claim 106, wherein said linear diffraction gratings of said second optical expander and said optical trapping element are with equal periodicity.

112. The method of claim 88, wherein each of said first and second light-transmissive substrates comprises a first surface and a second surface.

113. The method of claim 112, wherein said first optical expander is embodied in said first surface of said first light-transmissive substrate.

114. The method of claim 112, wherein said first optical expander is embodied in said second surface of said first light-transmissive substrate.

115. The method of claim 92, further comprising positioning a collimator for collimating said light produced by said input light source.

116. The method of claim 115, wherein said collimator comprises a converging lens.

117. The method of claim 115, wherein said collimator comprises a diffractive optical element carried by, or formed in, said first light-transmissive substrate.

118. The method of claim 88, further comprising positioning at least one optical element for redirecting light rays, positioned so as to reduce an overall size of the optical device.

119. The method of claim 118, wherein said at least one optical element is a 45 degrees mirror.

120. The method of claim 88, wherein each of said first optical expander and said second optical expander has a predetermined diffraction efficiency.

121. The method of claim 120, wherein said predetermined diffraction efficiency varies locally for achieving an output having substantially uniform light intensities.

122. The method of claim 120, wherein said predetermined diffraction efficiency varies locally for achieving an output having predefined intensities.

123. The method of claim 97, wherein said optical trapping element has a predetermined diffraction efficiency.

124. The method of claim 123, wherein said predetermined diffraction efficiency varies locally for achieving an output having substantially uniform light intensities.

125. The method of claim 123, wherein said predetermined diffraction efficiency varies locally for achieving an output having predefined intensities.

126. The method of claim 88, wherein said first and said second optical expanders are each independently a plurality of linearly stretched mini-prisms, carried by a variable light transmissive surface.

127. The method of claim 97, wherein said optical trapping element is a plurality of linearly stretched mini-prisms.

128. The method of claim 88, wherein said first light-transmissive substrate and said second light-transmissive substrate are of thickness ranging between about 0.5 mm and about 5 mm.

129. The method of claim 88, wherein said first light-transmissive substrate and said second light-transmissive substrate are each independently selected from the group consisting of glass and transparent plastic.

130. An optical device for enlarging an eye box, the optical device comprising:

a first light-transmissive substrate engaging a first plane; and

a second light-transmissive substrate engaging a second plane being spaced apart from said first plane;

said first and said second light-transmissive substrates designed and configured such that light passing through the device first experiences a substantially total internal reflection in said first light-transmissive substrate such that said light exits from said first light-transmissive substrate expanded in a first dimension, and then experiences a substantially total internal reflection in said second light-transmissive substrate such that said light exits from said second light-transmissive substrate expanded in a second dimension, such that light rays of said light passing through the device are multiplied into a plurality of substantially parallel outgoing rays exiting said second light-transmissive substrate, hence enlarging an eye box of the optical device in both said first and said second dimensions.

131. The optical device of claim 130, wherein said first and second planes are substantially parallel.

132. The optical device of claim 130, wherein said first and second dimensions are substantially orthogonal.

133. The optical device of claim 131, wherein said first and second dimensions are substantially orthogonal.

134. The optical device of claim 130, further comprising an input light source for producing said light.

135. The optical device of claim 134, wherein said input light source comprises an input display source, hence said light constitutes an image.

136. The optical device of claim 134, further comprising a collimator for collimating said light produced by said input light source.

137. The optical device of claim 136, wherein said collimator comprises a converging lens.

138. The optical device of claim 130, further comprising at least one optical element for redirecting light rays, positioned so as to reduce an overall size of the optical device.

139. The optical device of claim 138, wherein said at least one optical element is a 45 degrees mirror.

140. The optical device of claim 130, wherein said first light-transmissive substrate and said second light-transmissive substrate are of thickness ranging between about 0.5 mm and about 5 mm.

141. The optical device of claim 130, wherein said first light-transmissive substrate and said second light-transmissive substrate are each independently selected from the group consisting of glass and transparent plastic.