Projection apparatus using spatial light modulator with relay lens and dichroic combiner

• US 6,676,260 B2
• Filed: 04/25/2002
• Issued: 01/13/2004
• Est. Priority Date: 04/25/2002
• Status: Expired due to Term

• Current Assignee: IMAX Theatres International Limited (IMAX Corporation)
• Original Assignee: Eastman Kodak Company
• Inventors: Kessler, David, Cobb, Joshua M.
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US10/131,871
• Publication Number:
  US 20030202159A1
• Time in Patent Office: 628 Days
• Field of Search: 353/31, 353/33, 353/34, 353/37, 353/102, 353/100, 353/94, 349/5, 349/7, 349/8
• US Class Current: 353/31
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

A digital projection apparatus (10) for projection of a multicolor image includes a magnifying relay lens assembly (28) as part of the light modulation assembly (38) for each component color. The relay lens assembly (28) increases the effective f/# of incident light to the V-plate assembly (25) or V-prism assembly (27) that serves as dichroic combiner, used to combine modulated light of each color from each light modulation assembly (38) in order to form the multicolor image. The magnifying relay lens assembly (28) also provides a reduced working distance for the projection lens (32), allowing a lower-cost design and facilitating substitution of the projection lens (32) best suited for a display surface (40).

Claims

1. A projection apparatus for projecting a multicolor image, the apparatus comprising:

(a) a first light modulation assembly for forming a magnified real image having a first wavelength, a second light modulation assembly for forming a magnified real image having a second wavelength, and a third light modulation assembly for forming a magnified real image having a third wavelength, wherein each modulation assembly is similarly constructed and comprises;

(i) a spatial light modulator for modulating incident light from a light source to form a first image; and

,

(ii) a magnifying relay lens having a relay lens optical axis, said magnifying relay lens focusing said first image towards a dichroic combiner in order to form said magnified real image of said first image along said relay lens optical axis;

(b) said dichroic combiner combining each of said relay lens optical axes onto a common projection axis, in order to form said multicolor image from said magnified real image having said first wavelength, said magnified real image having said second wavelength, and said magnified real image having said third wavelength, said dichroic combiner comprising a first dichroic surface disposed along said common projection axis at a first oblique angle and, adjacently, a second dichroic surface disposed along said common projection axis at a perpendicular to said first oblique angle, wherein said first and said second dichroic surfaces are not crossed; and

(c) a projection lens for projecting said multicolor image.

2. A projection apparatus according to claim 1 wherein said first wavelength is red, said second wavelength is green, and said third wavelength is blue.

3. A projection apparatus according to claim 1 wherein each of said spatial light modulators is a reflective LCD.

4. A projection apparatus according to claim 1 wherein each of said spatial light modulators is a transmissive LCD.

5. A projection apparatus according to claim 1 wherein each of said spatial light modulators is a digital micromirror device.

6. A projection apparatus according to claim 1 wherein each of said light sources comprises a lamp.

7. A projection apparatus according to claim 1 wherein each of said light sources comprises a color filter.

8. A projection apparatus according to claim 1 wherein each of said light sources comprises a laser.

9. A projection apparatus according to claim 1 wherein each of said light sources comprises an LED.

10. A projection apparatus according to claim 1 further comprising a dichroic separator for providing said light source.

11. A projection apparatus according to claim 1 further comprising a polarizer for conditioning the light from each of said light sources.

12. A projection apparatus according to claim 1 wherein s each of aid magnifying relay lens provides 2×

magnification.

13. A projection apparatus according to claim 1 wherein each of said magnifying relay lens is double-telecentric.

14. A projection apparatus according to claim 3 wherein said first light modulation assembly, second light modulation assembly, and third light modulation assembly each further comprise a polarizing beamsplitter for directing said incident light having a predetermined polarization state to each of said spatial light modulators and for directing each of said first images to each of said magnifying relay lens.

15. A projection apparatus according to claim 14 wherein said polarizing beamsplitter is a wire-grid polarizing beamsplitter.

16. A projection apparatus according to claim 1 wherein said first light modulation assembly, second light modulation assembly, and third light modulation assembly each further comprise a polarizer.

17. A projection apparatus according to claim 1 wherein said magnifying relay lens for said first light modulation assembly is fabricated to be substantially identical to said magnifying relay lens for said second light modulation assembly.

18. A projection apparatus according to claim 1 wherein said multicolor image formed by said dichroic combiner is a real color-combined image.

19. A projection apparatus according to claim 1 wherein said multicolor image formed by said dichroic combiner is a virtual color-combined image.

20. A projection apparatus according to claim 1 wherein each of said magnified real images of said first image is focused prior to said dichroic combiner along said relay lens optical axis.

21. A projection apparatus according to claim 1 wherein each of said magnified real images of said first image is focused within said dichroic combiner along said relay lens optical axis.

22. A projection apparatus according to claim 1 wherein each of said magnified real images of said first image is focused following said dichroic combiner along said relay lens optical axis.

23. A projection apparatus for projecting a multicolor image comprising:

(a) a first light modulation assembly for forming a magnified real image having a first wavelength, a second light modulation assembly for forming a magnified real image having a second wavelength, and a third light modulation assembly for forming a magnified real image having a third wavelength, wherein each modulation assembly is similarly constructed and comprises;

(i) a spatial light modulator for modulating incident light from a light source to form a first image; and

,

(ii) a magnifying relay lens having a relay lens optical axis for focusing said first image along said relay lens optical axis;

(b) a dichroic combiner for combining each of said relay lens optical axes onto a common projection axis, in order to form said multicolor image from said magnified real image having said first wavelength, said magnified real image having said second wavelength, and said magnified real image having said third wavelength, said dichroic combiner comprising a first prism having a first internal dichroic surface disposed along said common projection axis at a first oblique angle and, adjacently, a second prism having a second internal dichroic surface disposed along said common projection axis at a perpendicular to said first oblique angle, and, adjacent to said second prism, a third prism for equalizing the optical path length; and

(c) a projection lens for projecting said multicolor image toward a display surface.

24. A projection apparatus according to claim 23 wherein said first wavelength is red, said second wavelength is green, and said third wavelength is blue.

25. A projection apparatus according to claim 23 wherein each of said spatial light modulators is a reflective LCD.

26. A projection apparatus according to claim 23 wherein each of said spatial light modulators is a transmissive LCD.

27. A projection apparatus according to claim 23 wherein each of said spatial light modulators is a digital micromirror device.

28. A projection apparatus according to claim 23 wherein each of said light sources comprises a lamp.

29. A projection apparatus according to claim 23 wherein each of said light sources comprises a color filter.

30. A projection apparatus according to claim 23 wherein each of said light sources comprises a laser.

31. A projection apparatus according to claim 23 wherein each of said light sources comprises an LED.

32. A projection apparatus according to claim 23 further comprising dichroic separators for providing each of said light source.

33. A projection apparatus according to claim 23 further comprising polarizers for conditioning the light from each of said light sources.

34. A projection apparatus according to claim 23 wherein each of said magnifying relay lens provides 2×

magnification.

35. A projection apparatus according to claim 23 wherein each of said magnifying relay lens is double-telecentric.

36. A projection apparatus according to claim 23 wherein said first light modulation assembly, second light modulation assembly, and third light modulation assembly each further comprise a polarizing beamsplitter for directing said incident light having a predetermined polarization state to said spatial light modulator and for directing said first image to said magnifying relay lens.

37. A projection apparatus according to claim 36 wherein said polarizing beamsplitter is a wire-grid polarizing beamsplitter.

38. A projection apparatus according to claim 23 wherein said first light modulation assembly, second light modulation assembly, and third light modulation assembly each further comprise a polarizer.

39. A projection apparatus according to claim 23 wherein said magnifying relay lens for said first light modulation assembly is fabricated to be substantially identical to said magnifying relay lens for said second light modulation assembly.

40. A projection apparatus according to claim 23 wherein said multicolor image formed by said dichroic combiner is a real color-combined image.

41. A projection apparatus according to claim 23 wherein said multicolor image formed by said dichroic combiner is a virtual color-combined image.

42. A projection apparatus according to claim 23 wherein each of said magnified real images of each of said first image is focused prior to said dichroic combiner along each of said relay lens optical axis.

43. A projection apparatus according to claim 23 wherein each of said magnified real images of said first image is focused within said dichroic combiner along each of said relay lens optical axis.

44. A projection apparatus according to claim 23 wherein each of said magnified real images of each of said first images is focused following said dichroic combiner along each of said relay lens optical axis.

45. A projection apparatus for projecting a multicolor image, the apparatus comprising:

(a) a first light modulation assembly for forming a magnified real image having a first wavelength, a second light modulation assembly for forming a magnified real image having a second wavelength, and a third light modulation assembly for forming a magnified real image having a third wavelength, wherein each modulation assembly is similarly constructed and comprises;

(i) a light source

(ii) a polarizing beamsplitter which transmits light from said light source having a first polarization and reflecting light having a second polarization;

(iii) a liquid crystal device for modulating incident light having said second polarization to form a first image; and

,

(iv) a magnifying relay lens having a relay lens optical axis lens for focusing said first image to form said magnified real image of said first image along said relay lens optical axis;

(b) a dichroic combiner for combining each of said relay lens optical axes onto a common projection axis, in order to form said multicolor image from said magnified real image having said first wavelength, said magnified real image having said second wavelength, and said magnified real image having said third wavelength, said dichroic combiner comprising a first prism having a first internal dichroic surface disposed along said common projection axis at a first oblique angle and, adjacently, a second prism having a second internal dichroic surface disposed along said common projection axis at a perpendicular to said first oblique angle, and, adjacently, a third prism for equalizing the optical path length; and

(c) a projection lens for projecting said multicolor image toward a display surface.

46. A projection apparatus according to claim 45 wherein said first wavelength is red, said second wavelength is green, and said third wavelength is blue.

47. A projection apparatus according to claim 45 wherein each of said light sources comprises a lamp.

48. A projection apparatus according to claim 45 wherein each of said light sources comprises a color filter.

49. A projection apparatus according to claim 45 wherein each of said light sources comprises a laser.

50. A projection apparatus according to claim 45 wherein each of said light sources comprises an LED.

51. A projection apparatus according to claim 45 further comprising a dichroic separator for providing each of said light sources.

52. A projection apparatus according to claim 45 further comprising a polarizer for conditioning light from each of said light sources.

53. A projection apparatus according to claim 45 wherein each of said magnifying relay lens provides 2×

magnification.

54. A projection apparatus according to claim 45 wherein each of said magnifying relay lens is double-telecentric.

55. A projection apparatus according to claim 45 wherein said first light modulation assembly, second light modulation assembly, and third light modulation assembly each further comprise a polarizer.

56. A projection apparatus according to claim 45 wherein said magnifying relay lens for said first light modulation assembly is fabricated to be substantially identical to said magnifying relay lens for said second light modulation assembly.

57. A projection apparatus according to claim 45 wherein said multicolor image formed by said dichroic combiner is a real color-combined image.

58. A projection apparatus according to claim 45 wherein said multicolor image formed by said dichroic combiner is a virtual color-combined image.

59. A projection apparatus according to claim 45 wherein said polarizing beamsplitter is a wire grid beamsplitter.

60. A projection apparatus according to claim 45 wherein each of said magnified real images of each of said first images is focused prior to said dichroic combiner along said relay lens optical axis.

61. A projection apparatus according to claim 45 wherein each of said magnified real images of said first image is focused within said dichroic combiner along said relay lens optical axis.

62. A projection apparatus according to claim 45 wherein each of said magnified real images of said first image is focused following said dichroic combiner along each of said relay lens optical axis.

63. A method for projecting a multicolor image toward a display surface comprising:

(a) forming a first magnified real image from a first incident light having a first wavelength comprising the steps of;

(a1) modulating said first incident light of said first wavelength at a first spatial light modulator to form a first image;

(a2) magnifying and relaying said first image along a first optical axis and toward a first dichroic surface to form said magnified real image having said first wavelength;

(b) forming a second magnified real image from a second incident light of a second wavelength comprising the steps of;

(b1) modulating said second incident light of said second wavelength at a second spatial light modulator to form a second image;

(b2) magnifying and relaying said second image along a second optical axis and toward said first dichroic surface to form said second magnified real image;

(c) forming a third magnified real image from a third incident light of a third wavelength comprising the steps of;

(c1) modulating said third incident light of said third wavelength at a third spatial light modulator to form a third image;

(c2) magnifying and relaying said third image along a third optical axis and toward a second dichroic surface to form said third magnified real image, said second dichroic surface perpendicular to but not crossing said first dichroic surface;

(d) combining, at said first dichroic surface, said first optical axis and said second optical axis onto a common optical axis, and combining, at said second dichroic surface, said third optical axis onto said common optical axis, in order to combine said magnified real image having said first wavelength, said magnified real image having said second wavelength, and said magnified real image having said third wavelength, thereby forming a multicolor image for projection; and

(e) projecting said multicolor image toward said display surface.

64. The method of claim 63 wherein the step of modulating said first incident light of said first wavelength comprises the step of modulating an LCD spatial light modulator.

65. The method of claim 63 wherein the step of modulating said first incident light of said first wavelength comprises the step of modulating a digital micromirror device.

66. The method of claim 63 wherein said first incident light of said first wavelength is from a lamp.

67. The method of claim 63 wherein said first incident light of said first wavelength is from a laser.

68. The method of claim 63 wherein said first incident light of said first wavelength is from an LED.

69. The method of claim 63 wherein the step of modulating said first incident light of said first wavelength comprises the step of modulating a red light, wherein the step of modulating said second incident light of said second wavelength comprises the step of modulating a green light, and wherein the step of modulating said third incident light of said third wavelength comprises the step of modulating a blue light.

70. The method of claim 63 wherein said first dichroic surface is contained within a first prism and said second dichroic surface is contained within a second prism.

71. The method of claim 63 wherein the step of forming said multicolor image for projection comprises the step of forming said multicolor image between said first dichroic surface and said second dichroic surface.

72. The method of claim 63 wherein the step of forming said multicolor image for projection comprises the step of forming said multicolor image before said first dichroic surface.

73. The method of claim 63 wherein the step of forming said multicolor image for projection comprises the step of forming said multicolor image after said second dichroic surface along said common optical axis.

74. A projection apparatus for projecting a multicolor image comprising:

(a) a first light modulation assembly for forming a first magnified image having a first wavelength comprising;

(i) a first spatial light modulator for modulating incident light from a first light source to form a first image;

(ii) a first magnifying relay lens having a first relay lens optical axis for focusing said first image to form said first magnified real image;

(b) a second light modulation assembly for forming a second magnified real image having a second wavelength comprising;

(i) a second spatial light modulator for modulating incident light from a second light source to form a second image;

(ii) a second magnifying relay lens having a second relay lens optical axis for focusing said second image to form said second magnified real image;

(c) a third light modulation assembly for forming a third magnified real image having a third wavelength comprising;

(i) a third spatial light modulator for modulating incident light from a third light source to form a third image;

(ii) a third magnifying relay lens having a third relay lens optical axis for focusing said third image to form said third magnified real image;

(d) a dichroic combiner for combining each of said relay lens optical axes onto a common projection axis, in order to form said multicolor image from each of said magnified real images, said dichroic combiner comprising a first dichroic surface disposed along said common projection axis at a first oblique angle and, adjacently, a second dichroic surface disposed along said common projection axis at a perpendicular to said first oblique angle, wherein said first and said second dichroic surfaces are not crossed; and

(e) a projection lens for projecting said multicolor image.