Illuminator method and device

• US 20080037116A1
• Filed: 08/10/2007
• Published: 02/14/2008
• Est. Priority Date: 04/18/2006
• Status: Active Grant

• Current Assignee: Upstream Engineering Oy
• Original Assignee: Upstream Engineering Oy
• Inventors: Viljamaa, Teuvo, Alasaarela, Ilkka, Soukkamaki, Jussi
• Granted Patent: US 7,729,578 B2
• Time in Patent Office: Days
• US Class Current: 359/433
• CPC Class Codes: F21V 13/04 the elements being reflectors and refractors for vehicle rear lights F21S43/40
• CPC Class Codes: F21V 5/046 the lens having a rotationally symmetrical shape about an axis for transmitting light in a direction mainly perpendicular to this axis, e.g. ring or annular lens with light source disposed inside the ring
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0061 the light source comprising a LED semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission H01L33/00
• CPC Class Codes: G02B 21/06 Means for illuminating specimens

Abstract

A first toroidal ray guide defines an axis of revolution and has a toroidal entrance pupil adapted to image light incident on the entrance pupil at an angle to the axis of revolution between 40 and 140 degrees, and it also has a first imaging surface opposite the entrance pupil. A second toroidal ray guide also defines the same axis of revolution and has a second imaging surface adjacent to the first imaging surface. Various additions and further qualities of the ray guides, which form optical channels, are disclosed. In a method light emanating from a source at between 40-140 degrees from an optical axis is received at an entrance pupil of a ray guide arrangement that is circularly symmetric about the optical axis. Then the received light is redirected through the ray guide arrangement to an exit pupil in an average direction substantially parallel to the optical axis.

Claims

1. An apparatus comprising:

a first toroidal ray guide defining an axis of revolution and having a toroidal entrance pupil adapted to image radiation incident on the entrance pupil at an angle to the axis of revolution between 40 and 140 degrees, said first toroidal ray guide having a first imaging surface opposite the entrance pupil; and

a second ray guide also defining the axis of revolution and having a second imaging surface adjacent to the first imaging surface.

2. The apparatus of claim 1, wherein the angle is between 45 and 135 degrees.

3. The apparatus of claim 1, wherein a surface of the first toroidal ray guide outboard from the axis of revolution comprises a reflective surface.

4. The apparatus of claim 1, wherein the said toroidal entrance pupil comprises a first entrance pupil and wherein the first imaging surface is adjacent to a first portion of the second imaging surface, the apparatus further comprising:

a third toroidal ray guide also defining the axis of revolution and having a toroidal second entrance pupil adapted to image radiation incident on the entrance pupil at an angle to the axis of revolution between 40 and 140 degrees, said third toroidal ray guide having a third imaging surface opposite the second entrance pupil, and wherein the third toroidal ray guide is disposed inboard the first toroidal ray guide.

5. The apparatus of claim 4, further comprising a light source disposed along the axis of revolution such that light emanating directly from the source is incident on the entrance pupil at an angle to the axis of revolution between 40 and 140 degrees, and the axis of revolution comprises a system optical axis of the apparatus.

6. The apparatus of claim 5, wherein:

the first entrance pupil is adapted to guide substantially all light incident upon it from the light source through the first toroidal ray guide and to the first imaging surface; and

the second entrance pupil is adapted to guide substantially all light incident upon it from the light source through the third toroidal ray guide and to the third imaging surface.

7. The apparatus of claim 1, wherein the first toroidal ray guide and the second toroidal ray guide are made of a same optical material having a refractive index between about 1.3 and about 1.7.

8. The apparatus of claim 7, wherein the same optical material is selected from the group consisting of cyclic olefin copolymer, polymethyl methacrylate, polycarbonate, and polystyrene.

9. The apparatus of claim 1, further comprising a light source disposed along the axis of revolution such that light emanating directly from the source is incident on the entrance pupil at an angle to the axis of revolution between 40 and 140 degrees, wherein the axis of revolution comprises a system optical axis of the apparatus.

10. The apparatus of claim 7, wherein the light source is disposed between a reflective surface and a substantially hemispherical dome that faces the entrance pupil.

11. The apparatus of claim 10, wherein at least one of the dome and the entrance pupil comprises a fourth imaging surface.

12. The apparatus of claim 11, wherein the fourth imaging surface and the first imaging surface are adapted to form an intermediate image from the light source at a plane perpendicular to the system optical axis and adjacent to the first imaging surface.

13. The apparatus of claim 12, wherein the second toroidal ray guide comprises an exit pupil disposed opposite the second imaging surface, the exit pupil comprising a fifth imaging surface.

14. The apparatus of claim 7, wherein the first toroidal ray guide is adapted so as to redirect substantially all light incident at the entrance pupil from the light source to the first imaging surface.

15. The apparatus of claim 7, wherein the first and second toroidal ray guides are adapted so as to convert substantially uniform circular illumination from the light source to substantially uniform rectilinear illumination at the exit pupil.

16. The apparatus of claim 1, further comprising a Fresnel lens centered on the axis of revolution.

17. The apparatus of claim 16, wherein outboard portions of the Fresnel lens lie adjacent to the second imaging surface.

18. The apparatus of claim 1, wherein the second ray guide is a toroidal ray guide.

19. A method comprising:

emanating radiation from a source disposed along an optical axis at an angle between 40 and 140 degrees from the optical axis;

receiving the emanated radiation at an entrance pupil of a ray guide arrangement, said ray guide arrangement being circularly symmetric about the optical axis;

redirecting the received radiation through the ray guide arrangement to an exit pupil in an average direction substantially parallel to the optical axis.

20. The method of claim 19, wherein the received radiation comprises light having substantially uniform circular illumination and the redirected radiation comprises redirected light at the exit pupil having substantially uniform rectilinear illumination.

21. The method of claim 19, wherein the angle is between 45 and 135 degrees.

22. The method of claim 19, wherein the circularly symmetric ray guide arrangement comprises first and second imaging surfaces disposed between the entrance pupil and the exit pupil that form an intermediate image from the received light.

23. The method of claim 22, wherein the circularly symmetric ray guide arrangement comprises a first toroidal ray guide and a second ray guide arranged in optical series with one another, wherein the first toroidal ray guide defines the entrance pupil and the first imaging surface and the second ray guide defines the exit pupil and the second imaging surface.

24. The method of claim 23, wherein the circularly symmetric ray guide arrangement further comprises a third toroidal ray guide arranged in optical series with the second ray guide and in optical parallel with the first toroidal ray guide, said third toroidal ray guide defining another entrance pupil.

25. The method of claim 23, wherein a surface of the first toroidal ray guide outboard from the optical axis comprises a reflective surface.

26. The method of claim 24, wherein the radiation comprises light and wherein redirecting the received light through the circularly symmetric ray guide arrangement comprises:

guiding substantially all light incident upon the entrance pupil of the first toroidal ray guide from the source through the first toroidal ray guide and to the first imaging surface; and

guiding substantially all light incident upon the another entrance pupil of the third toroidal ray guide from the source through the third toroidal ray guide and to the third imaging surface.

27. The method of claim 23, wherein emanating radiation from the source comprises propagating the radiation through a substantially hemispherical dome that faces the entrance pupil.

28. The method of claim 27, wherein at least one of the dome and the entrance pupil comprises a fourth imaging surface.

29. The method of claim 28, wherein the fourth imaging surface and the first imaging surface are adapted to form an intermediate image from the source at a plane perpendicular to the optical axis and adjacent to the first imaging surface.

30. The method of claim 29, wherein the second ray guide comprises a fifth imaging surface disposed opposite the second imaging surface.

31. The method of claim 23, wherein the second ray guide is a toroidal ray guide.

32. An apparatus comprising:

at least one ray guide substantially cylindrically symmetrical about an axis;

said at least one ray guide being arranged to substantially image at least a portion of the rays, which emanate from a non-point object towards an entrance pupil of the said at least one ray guide, to an image;

and in each individual cross-sectional plane which includes the said axis and a portion of the entrance pupil, said at least one ray guide being arranged to image an individual subset of the rays which emanate from the non-point object along the individual cross-sectional plane towards a portion of the entrance pupil which is on the individual cross-sectional plane and on one side of the axis to an intermediate image on the individual cross-sectional plane, and to further substantially image the at least a portion of the rays from the intermediate image to an cross-sectional image on the cross-sectional plane, which cross-sectional image substantially coincides with a cross-section of the image at the said individual cross-sectional plane, such that no two said intermediate images of two different individual cross-sectional planes cross each other.

33. An apparatus of claim 32, wherein said at least one ray guide is arranged such that no ray of the individual subset of rays crosses the axis between the said cross-section of the entrance pupil and the cross-section of the exit pupil of the said at least one ray guiding component which is on the same half of the individual cross-sectional plane in respect to the axis than the said cross-section of the entrance pupil.

34. The apparatus of claim 32, wherein the at least one ray guide is arranged to substantially image the entrance pupil to the exit pupil on each of the cross-sectional half planes bounded by the axis.

35. The apparatus of claim 32, wherein said at least one ray guide is arranged to substantially image substantially all rays, which emanate from the non-point object towards the entrance pupil of the said at least one ray guide, to the image.

36. The apparatus of claim 32, wherein said at least one ray guide is arranged such that conjugate points in the entrance pupil and in the exit pupil are spaced from the axis by a substantially equal distance.

37. The apparatus of claim 32, wherein said at least one ray guide is arranged such that any point which is substantially imaged from the non-point object to the image forms a spot on the image such that its root mean square-spot size is substantially smaller than a mean diameter of the image.

38. The apparatus of claim 37, wherein the root mean square-spot size is smaller than one fourth of the mean diameter of the image.

39. The apparatus of claim 32, wherein said at least one ray guide is arranged such that an average distance from the non-point object to the entrance pupil is substantially larger than a mean distance from the non-point object to the axis.

40. The apparatus of claim 39;

wherein said average distance from the non-point object to the entrance pupil is at least three times larger than the mean distance from the non-point object to the axis.

41. The apparatus of claim 32, wherein the rays are rays of electromagnetic radiation between ultraviolet and infrared wavelengths.

42. The apparatus of claim 41, wherein the rays of electromagnetic radiation are rays emitted from a light-emitting diode.

43. The apparatus of claim 32, which is an illumination component of an image forming system.

44. The apparatus of claim 32, wherein said at least one ray guide is arranged such that at least one line between the entrance pupil and a point on the axis, which point is nearest to an average point of the non-point object, forms an angle greater than 35 degrees with the axis.

45. The apparatus of claim 32, wherein said at least one ray guide is arranged such that every line between the entrance pupil and a point on the axis, which point is nearest to an average point of the non-point object, forms an angle greater than 30 degrees with the axis.

46. The apparatus of claim 32, wherein said at least one ray guide is arranged to change the propagation direction of the at least portion of the rays successively at least in three distinct locations per ray.

47. The apparatus of claim 32, wherein said at least one ray guide is arranged to change the propagation direction of the at least portion of the rays successively at no more than five distinct locations per ray.

48. The apparatus of claim 32, wherein said at least one ray guide is arranged such that the entrance pupil covers a solid angle of at least 0.1 steradians about a point on the axis which is nearest to an average point of the non-point object.

49. An apparatus comprising:

at least one ray guiding component substantially cylindrically symmetrical about an axis of revolution;

said at least one ray guiding component being arranged to substantially image at least a portion of the rays, which emanate from a non-point object towards an entrance pupil of the said at least one ray guiding component, to an image;

said at least one ray guiding component being arranged to substantially image the entrance pupil into an exit pupil of the said at least one ray guiding component, such that each point on the entrance pupil is substantially imaged to a projection of the point substantially along the direction of the said axis of revolution on the exit pupil;

said at least one ray guiding component being arranged to have substantially all points of the entrance pupil at approximately a same distance from the object; and

said at least one ray guiding component being arranged so that no path of any meridional ray imaged from the entrance pupil into the exit pupil crosses the said axis of revolution between the entrance pupil and the exit pupil.

50. The apparatus of claim 49, wherein said at least one ray guiding component is arranged to substantially image substantially all rays, which emanate from the non-point object towards the entrance pupil of the said at least one ray guiding component, to the image.

51. The apparatus of claim 49, wherein said at least one ray guiding component is arranged such that any point which is substantially imaged from the non-point object to the image forms a spot on the image such that its root mean square-spot size is substantially smaller than a mean diameter of the image.

52. The apparatus of claim 49, wherein the root mean square-spot size is smaller than one fourth of a mean diameter of the image.

53. The apparatus of claim 49, wherein said at least one ray guiding component is arranged such that an average distance from the non-point object to the entrance pupil is substantially larger than a mean distance from the object to the axis.

54. The apparatus of claim 53;

wherein said average distance from the non-point object to the entrance pupil is at least three times larger than the mean distance from the non-point object to the axis.

55. The apparatus of claim 49, wherein the rays are rays of electromagnetic radiation between ultraviolet and infrared wavelengths.

56. The apparatus of claim 55, wherein the rays of electromagnetic radiation are rays emitted from a light-emitting diode.

57. The apparatus of claim 49, which is an illumination component of an image forming system.

58. The apparatus of claim 49, wherein said at least one ray guiding component is arranged such that at least one line between the entrance pupil and the point on the axis, which point is nearest to an average point of the non-point object, forms an angle greater than 35 degrees with the axis.

59. The apparatus of claim 49, wherein said at least one ray guiding component is arranged such that every line between the entrance pupil and a point on the axis, which point is nearest to an average point of the non-point object, forms an angle greater than 30 degrees with the axis.

60. The apparatus of claim 49, wherein said at least one ray guiding component is arranged to change the propagation direction of the at least portion of the rays successively at no more than five distinct locations per ray.

61. The apparatus of claim 49, wherein said at least one ray guiding component is arranged to have length along the axis smaller than a diameter of the exit pupil.

62. The apparatus of claim 49, wherein said at least one ray guiding component is arranged such that the entrance pupil covers a solid angle of at least 3 steradians about a point on the axis, which point is nearest to an average point of the non-point object.