Rippled mixers for uniformity and color mixing

• US 20070024971A1
• Filed: 05/26/2006
• Published: 02/01/2007
• Est. Priority Date: 07/29/2005
• Status: Active Grant

• Current Assignee: Synopsys Incorporated
• Original Assignee: Synopsys Incorporated
• Inventors: McGuire, James, Cassarly, William, Davenport, Thomas
• Granted Patent: US 7,777,955 B2
• Time in Patent Office: Days
• US Class Current: 359/487
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• 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
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0096 the lights guides being of the hollow type
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers

Abstract

Various embodiments described herein comprise mixers comprising a light pipe having input and output ends and a central region therebetween. An optical path extends in a longitudinal direction from the input end through the central region to the output end. The central region of the light pipe comprises one or more rippled reflective sidewalls having a plurality of elongate ridges and valleys and sloping surfaces therebetween. Light from the input end propagating along the optical path reflects from the sloping surfaces and is redirected at a different azimuthal direction toward the output end thereby mixing the light at the output end. Illuminance and/or color mixing can therefore be provided.

Claims

1. An illumination system comprising:

a plurality of light emitting diodes; and

a mixer comprising a light pipe having input and output ends and a central region therebetween, an optical path extending in a longitudinal direction from said input end through said central region to said output end, said plurality of light emitting diodes disposed in proximity to said input end,

wherein said central region of said light pipe comprises one or more rippled sidewalls having a plurality of elongate ridges and valleys and sloping surfaces therebetween, said ridges and valleys comprising vertices at least partially formed by a rounded surface or at least partially formed by two or more substantially nonorthogonal surfaces,

wherein light from said plurality of light emitting diodes propagating along said optical path reflects from said sloping surfaces and is redirected at a different azimuthal direction toward said output end thereby mixing said light at said output end.

2. The illumination system of claim 1, wherein a portion of said vertices are formed by rounded sloping surfaces and another portion of said vertices are formed by faceted sloping surfaces.

3. The illumination system of claim 1, wherein said plurality of light emitting diodes comprises different color light emitting diodes.

4. The illumination system of claim 3, wherein said plurality of light emitting diodes comprises red, blue, and green light emitting diodes.

5. The illumination system of claim 1, wherein said plurality of light emitting diodes comprises a linear array.

6. The illumination system of claim 1, wherein said plurality of light emitting diodes comprises a diode array comprising a plurality of rows and columns of light emitting diodes.

7. The illumination system of claim 1, further comprising a reflective collector at said input end that receives light from said plurality of light emitting diodes and directs said light into said light pipe.

8. The illumination system of claim 7, wherein said reflective collector comprises an elliptical collector having an ellipsoidally shaped reflective surface.

9. The illumination system of claim 1, wherein said light pipe comprises a hollow light pipe with said central region being open.

10. The illumination system of claim 9, wherein said sidewalls comprise a reflective film.

11. The illumination system of claim 10, wherein said reflective film comprises metallization or a dielectric multilayer coating.

12. The illumination system of claim 1, wherein said light pipe comprises a solid light pipe and said central region comprises substantially optically transmissive material.

13. The illumination system of claim 12, wherein said central region comprises glass or plastic.

14. The illumination system of claim 1, wherein said light pipe comprises a flexible light pipe.

15. The illumination system of claim 14, wherein said light pipe comprises an optical fiber.

16. The illumination system of claim 15, wherein said optical fiber has a core diameter of least about 3 millimeters.

17. The illumination system of claim 1, wherein said light pipe comprises one or more substantially planar rippled sidewalls.

18. The illumination system of claim 1, wherein said light pipe comprises one or more substantially curved rippled sidewalls.

19. The illumination system of claim 1, wherein said light pipe comprises a right circular cylinder, said output end having a circular cross-section such that said light pipe outputs a substantially circular beam.

20. The illumination system of claim 1, wherein said light pipe comprises a right prism defined by four planar sidewalls such that said output end has a square or rectangular cross-section and said light pipe outputs a substantially square or rectangular shaped beam.

21. The illumination system of claim 1, wherein said light pipe has a width of between about 1 millimeter and about 12 millimeters.

22. The illumination system of claim 1, wherein said light pipe has a length of between about 2 millimeters and about 35 millimeters.

23. The illumination system of claim 1, wherein said sloping surfaces comprise planar surfaces.

24. The illumination system of claim 23, wherein a given sloping surface comprises a plurality of facets.

25. The illumination system of claim 1, wherein said ridges and valleys are curved.

26. The illumination system of claim 1, wherein said ridges are rounded.

27. The illumination system of claim 1, wherein size, shape, or spacing of the ridges varies for different ridges or valleys.

28. The illumination system of claim 1, wherein said ridges have an average spacing of between about 1 percent and about 30 percent of the width of said light pipe.

29. The illumination system of claim 1, wherein said ridges have an average spacing of between about 1 micron and about 1000 microns.

30. The illumination system of claim 1, wherein said ridges have an average height measured with respect to said valleys of between about 1 micron and about 1000 microns.

31. The illumination system of claim 1, wherein said elongate ridges have the same heights.

32. The illumination system of claim 1, wherein said elongate ridges have different heights.

33. The illumination system of claim 1, wherein said elongate ridges have an average vertex angle of between about 15 degrees and about 65 degrees.

34. The illumination of claim 1, wherein said ridges have an average angle α

of between about 10 degrees and about 65 degrees.

35. The illumination system of claim 1, wherein said ridges have an average angle α

of between about 10 degrees and about 25 degrees.

36. The illumination system of claim 1, wherein said vertices of said ridges are formed by rounded surfaces.

37. The illumination system of claim 36, wherein said ridges have an angle α

of between about 20 degrees and about 37 degrees.

38. The illumination system of claim 1, wherein said elongate ridges have a constant spacing therebetween.

39. The illumination system of claim 1, wherein said elongate ridges have varying spacing therebetween.

40. The illumination system of claim 1, wherein said elongate ridges have an average length of between about 50 percent and about 100 percent of the length of the light pipe.

41. The illumination system of claim 1, wherein said elongate ridges have an average length of between about 0.1 centimeters and about 10 centimeters.

42. The illumination system of claim 1, wherein said elongate ridges extend along a direction parallel to said longitudinal direction.

43. The illumination system of claim 1, wherein said elongate ridges are oriented at an angle with respect to said longitudinal direction.

44. The illumination system of claim 43, wherein said angle is between about 5 degrees and about 40 degrees.

45. The illumination system of claim 1, wherein a first portion of said elongate ridges and valleys are oriented at an angle with respect to said longitudinal direction and a second portion of said elongate ridges and valleys are oriented at a different angle with respect to said longitudinal direction.

46. The illumination system of claim 1, wherein a first portion of said elongate ridges and valleys cross a second portion of said elongate ridges and valleys.

47. The illumination system of claim 1, wherein light reflects from said sloping surfaces via total internal reflection.

48. The illumination system of claim 1, wherein the illumination system comprises a flashlight.

49. The illumination system of claim 1, wherein the illumination system comprises a portable light.

50. The illumination system of claim 1, wherein light entering said input end is mixed such that the standard deviation of the illuminance distribution is reduced to less than 5 percent at said output end.

51. The illumination system of claim 1, wherein light of varying color entering said input end is mixed such that the standard deviation of the delta_u′

_v′

of the color of the light is reduced to less than 0.003 at said output end.

52. The illumination system of claim 1, wherein one or more of said ridges are asymmetrical.

53. A lighting apparatus comprising:

a light source comprising a plurality of emitters; and

a mixer having an input and an output and a central region therebetween, said mixer comprising at least one rippled surface in said central region comprising a plurality of peaks and valleys connected by sloping surface portions, said peaks and valleys each comprising a vertex at least partially formed by a rounded surface portion or by two or more substantially nonorthogonal surface portions,

wherein light entering said input propagating longitudinally along said central region is deflected by said sloping surface portions of said rippled surface in an azimuthal direction thereby increasing mixing of said light in said mixer and uniformity at said output.

54. The lighting apparatus of claim 53, wherein said plurality of emitters comprises a plurality of light emitting diodes.

55. The lighting apparatus of claim 54, wherein said plurality of emitters comprises red, green, and blue light emitting diodes.

56. The lighting apparatus of claim 53, wherein said plurality of emitters comprises at least one emitter that emits light of a shorter wavelength and a phosphor that converts said light having said shorter wavelength into light having a longer wavelength.

57. The lighting apparatus of claim 56, wherein said plurality of emitters comprises a plurality of visible wavelength emitters and said at least one emitter that emits light of a shorter wavelength comprises a UV light emitter.

58. The lighting apparatus of claim 53, wherein said mixer comprises sidewalls defining a cavity for propagation of light therein, said at least one rippled surface being disposed within said cavity spaced apart from said sidewalls.

59. The lighting apparatus of claim 58, wherein said sidewalls comprise a reflective material.

60. The lighting apparatus of claim 58, wherein said cavity comprises substantially optically transmissive material.

61. The lighting apparatus of claim 58, wherein said at least one rippled surface is substantially transmissive.

62. The lighting apparatus of claim 53, wherein said mixer comprises a flexible light pipe.

63. The lighting apparatus of claim 53, wherein said mixer comprises an optical fiber.

64. The lighting apparatus of claim 63, wherein said optical fiber has a core diameter of at least 3 millimeters in diameter.

65. The lighting apparatus of claim 53, wherein said peaks are rounded.

66. The lighting apparatus of claim 53, wherein size, shape, or spacing of the ridges varies for different peaks or valleys.

67. The lighting apparatus of claim 53, wherein said light source comprises an incoherent light source.

68. The lighting apparatus of claim 53, wherein the illumination system comprises a flashlight.

69. The lighting apparatus of claim 53, wherein the illumination system comprises a portable light.

70. The lighting apparatus of claim 53, wherein light entering said input is mixed such that the standard deviation of the illuminance distribution is reduced to less than 5 percent at said output.

71. The lighting apparatus of claim 53, wherein light of varying color entering said input is mixed such that the standard deviation of the delta_u′

_v′

of the color of the light is reduced to less than 0.003 at said output.

72. The lighting apparatus of claim 53, wherein said peaks have an average apex angle of between about 15 degrees and about 65 degrees.

73. The lighting apparatus of claim 53, wherein said peaks have an average angle α

of between about 10 degrees and about 65 degrees.

74. The lighting apparatus of claim 53, wherein said peaks have an average angle α

of between about 10 degrees and about 25 degrees.

75. The lighting apparatus of claim 53, wherein said vertices of said peaks are formed by round surfaces.

76. The lighting apparatus of claim 75, wherein said peaks have an angle α

of between about 20 degrees and about 37 degrees.

77. The lighting apparatus of claim 75, wherein one or more of said peaks are asymmetrical.

78. A mixer for mixing light, said mixer comprising:

an elongate member having an input and an output and a central region therebetween, said input having a different size or shape than said output, said elongate member comprising at least one rippled surface in said input, output, and central region comprising a plurality of peaks and valleys connected by sloping surface portions, such that light entering said input propagating longitudinally along said central region is deflected by said sloping surface portions of said rippled surface in an azimuthal direction thereby increasing mixing of said light and uniformity at said output.

79. The lighting apparatus of claim 78, wherein said input has a different size than said output.

80. The lighting apparatus of claim 79, wherein said elongate member has a length that is sufficiently long such that etendue is substantially conserved from said input to said output.

81. The lighting apparatus of claim 78, wherein said input has a different shape than said output.

82. The lighting apparatus of claim 81, wherein said input has a rectilinear shaped aperture and said output has a curvilinear shaped aperture.

83. The lighting apparatus of claim 81, wherein said output comprises a curved output face having optical power.

84-87. -87. (canceled)

88. A lighting apparatus comprising:

a mixer having an input and an output and a central region therebetween, said mixer comprising at least one rippled surface in said central region comprising a plurality of peaks and valleys connected by sloping surface portions, such that light entering said input propagating longitudinally along said central region of said mixer is deflected by said sloping surface portions of said rippled surface in an azimuthal direction thereby increasing mixing of said light in said mixer and uniformity at said output; and

a projection lens disposed to receive light from said mixer output and project said light to an enlarged spot.

89. The lighting apparatus of claim 88, further comprising a translator configured to longitudinally translate said mixer or said projection lens to adjust the longitudinal separation therebetween and provide optical zoom.

90. The lighting apparatus of claim 89, further comprising a collector lens disposed proximal to said output of said mixer.

91. The lighting apparatus of claim 90, wherein said collector lens is attached to said mixer and said mixer and collector lens are movable with respect to said projection lens or said projection lens is movable with respect to said mixer and said collector lens.

92. The lighting apparatus of claim 88, further comprising a diffuser disposed between said mixer and said projection lens and a translator configured to alter the longitudinal distance separating the diffuser and the mixer, the longitudinal distance separating the diffuser and the projection lens, or both, to provide optical zoom.

93. The lighting apparatus of claim 92, wherein said diffuser has an optical aperture therein.

94. The lighting apparatus of claim 88, wherein said projection lens comprises a TIR lens.

95. The lighting apparatus of claim 88, wherein said projection lens is integrated with said mixer through a tapered region, said mixer coupled to a first end of said tapered region and said projection lens coupled to a second end of said tapered region thereby forming a single unitary piece.

96. The lighting apparatus of claim 95, wherein said mixer, said tapered region, and said projection lens comprise the same material.

97. The lighting apparatus of claim 88, wherein said peaks comprise rounded portions.

98-117. -117. (canceled)

118. A mixer for mixing light, said mixer comprising:

an elongate member having an input face and an output face and a central region therebetween, said elongate member comprising at least one rippled surface in said central region comprising a plurality of peaks and valleys connected by sloping surface portions, such that light entering said input face propagating longitudinally along said central region is deflected by said sloping surface portions of said rippled surface in an azimuthal direction thereby increasing mixing of said light and uniformity at said output face; and

a non-imaging optical element at said input or said output,

wherein at least one or more of said peaks comprise rounded surfaces surface portions.

119. The mixer of claim 118, wherein said non-imaging optical element comprises a compound parabolic collector.

120-125. -125. (canceled)

126. A mixer for mixing light, said mixer comprising:

an elongate member having an input face and an output face and a central region therebetween, said elongate member comprising at least one rippled surface in said central region comprising a plurality of peaks and a plurality of valleys connected by sloping surface portions, such that light entering said input face propagating longitudinally along said central region is deflected by said sloping surface portions of said rippled surface in an azimuthal direction thereby increasing mixing of said light and uniformity at said output face,

wherein a first portion of said plurality of peaks are formed by rounded sloping surface portions and a second portion of said plurality of peaks are formed by substantially planar sloping surface portions.

127. The mixer of claim 126, wherein said first and second portions of said plurality of peaks are dispersed such that one or more peaks formed by rounded sloping surface portions are between two peaks formed by substantially planar sloping surface portions.

128-135. -135. (canceled)