Lensed tapered optical waveguide

• US 20050047723A1
• Filed: 09/28/2004
• Published: 03/03/2005
• Est. Priority Date: 05/25/2001
• Status: Active Grant

• Current Assignee: Kenneth K. Li
• Original Assignee: Kenneth K. Li
• Inventors: Li, Kenneth K.
• Granted Patent: US 6,898,353 B2
• Time in Patent Office: Days
• US Class Current: 385/43
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0047 for use with a light source G02B19/009, G02B19/0095 take precedence; details of lighting devices in general F21V; non-semiconductor lasers having optical devices external to the laser cavity H01S3/005
• CPC Class Codes: G02B 26/008 in the form of devices for effecting sequential colour changes, e.g. colour wheels
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 6/0006 Coupling light into the fibre in general G02B6/4298
• CPC Class Codes: G02B 6/10 of the optical waveguide type G02B6/02, G02B6/24 take precedence; devices or arrangements for the control of light by electric, magnetic, electro-magnetic or acoustic means G02F1/00; transferring the modulation of modulated light G02F2/00; optical logic elements G02F3/00; optical analogue/digital converters G02F7/00
• CPC Class Codes: G02B 6/4206 Optical features G02B6/4207, G02B6/421 take precedence
• CPC Class Codes: G02B 6/4214 the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device G02B6/4246 takes precedence
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

An optical coupling element for use in large numerical aperture collecting and condensing systems. The optical coupling element includes a curved surface such as a lens at the output of a tapered light pipe (TLP). The TLP in combination with the curved surface alters the divergence angle and the area of the light exiting the curved surface. Electromagnetic radiation emitted by a source is collected and focused onto a target by positioning the source of electromagnetic radiation substantially at a first focal point of a primary reflector so that the primary reflector produces rays of radiation reflected from the primary reflector that converge at a second focal point of the secondary reflector. The optical coupling element is positioned so that its input end is substantially proximate with the second focal point of the secondary reflector. The converging rays of radiation reflected from the secondary reflector pass through input end and are transmitted towards the curved surface, where their divergence angle and area are adjusted.

Claims

1. A TLP comprising;

an input end;

a substantially convex output end substantially transparently connected to said input end;

said input end being illuminated with electromagnetic radiation;

wherein a first NA of said radiation is transformed into a second NA by said TLP; and

wherein said first NA is substantially unequal to said second NA.

2. The TLP of claim 1, comprising further a source of said electromagnetic radiation, said source comprising:

a reflector having a first and a second focal points;

said source being located proximate to said first focal point of said reflector to produce rays of radiation that reflect from said reflector to converge substantially at said second focal point; and

wherein said input end of said TLP is located proximate to said second focal point of said secondary reflector.

3. The TLP of claim 2, wherein said reflector has a coating that reflects only a pre-specified portion of the electromagnetic radiation spectrum.

4. The TLP of claim 2, wherein said coating only reflects visible light radiation, a pre-specified band of radiation, or a specific color of radiation.

5. The TLP of claim 2, wherein said reflector comprises a primary reflector having a first optical axis, and said first focal point is a focal point of said primary reflector, said reflector comprising further:

a secondary reflector having a second optical axis placed substantially symmetrically to said primary reflector such that said first and second optical axes are substantially collinear, and wherein said second focal point is a focal point of said secondary reflector; and

wherein said rays of radiation reflect from said primary reflector toward said secondary reflector and converge substantially at said second focal point.

6. The TLP of claim 5, wherein:

said primary reflector comprises at least a portion of a substantially elliptical surface of revolution; and

said secondary reflector comprises at least a portion of a substantially hyperbolic surface of revolution.

7. The TLP of claim 5, wherein:

said primary reflector comprises at least a portion of a substantially hyperbolic surface of revolution; and

said secondary reflector comprises at least a portion of a substantially elliptical surface of revolution.

8. The TLP of claim 5, wherein:

a corner of said primary reflector is truncated along a plane substantially parallel to said first optical axis.

9. The TLP of claim 5, wherein:

a corner of said secondary reflector is truncated along a plane substantially parallel to said second optical axis.

10. The TLP of claim 2, comprising further a retro-reflector disposed opposite said reflector to reflect at least a portion of the electromagnetic radiation that does not impinge directly on said reflector toward said reflector through the first focal point of said reflector to increase the flux intensity of the converging rays.

11. The TLP of claim 10, wherein said retro-reflector comprises a spherical retro-reflector disposed on a side of said source opposite said primary reflector to reflect electromagnetic radiation emitted from said source in a direction away from said primary reflector toward said primary reflector through the first focal point of said primary reflector.

12. The TLP of claim 3, wherein said source comprises a light-emitting arc lamp.

13. The TLP of claim 12, wherein said arc lamp comprises a lamp selected from the group comprising a xenon lamp, a metal halide lamp, an HID lamp, or a mercury lamp.

14. The TLP of claim 2, wherein said source comprises a filament lamp.

15. A NA conversion device comprising:

a polygonal input end;

an output end substantially transparently connected to said polygonal input end;

said polygonal input end being illuminated with electromagnetic radiation;

wherein a first NA of said radiation is transformed into a second NA by said TLP; and

wherein said first NA is substantially unequal to said second NA.

16. The NA conversion device of claim 15, wherein said output end is flat.

17. The NA conversion device of claim 15, wherein said output end is convex.

18. The NA conversion device of claim 15, comprising further a source of said electromagnetic radiation, said source comprising:

a reflector having a first and a second focal points;

said source being located proximate to said first focal point of said reflector to produce rays of radiation that reflect from said reflector to converge substantially at said second focal point; and

wherein said input end of said TLP is located proximate to said second focal point of said secondary reflector.

19. The NA conversion device of claim 18, wherein said reflector has a coating that reflects only a pre-specified portion of the electromagnetic radiation spectrum.

20. The NA conversion device of claim 18, wherein said coating only reflects visible light radiation, a pre-specified band of radiation, or a specific color of radiation.

21. The NA conversion device of claim 18, wherein said reflector comprises a primary reflector having a first optical axis, and said first focal point is a focal point of said primary reflector, said reflector comprising further:

a secondary reflector having a second optical axis placed substantially symmetrically to said primary reflector such that said first and second optical axes are substantially collinear, and wherein said second focal point is a focal point of said secondary reflector; and

wherein said rays of radiation reflect from said primary reflector toward said secondary reflector and converge substantially at said second focal point.

22. The NA conversion device of claim 21, wherein:

said primary reflector comprises at least a portion of a substantially elliptical surface of revolution; and

said secondary reflector comprises at least a portion of a substantially hyperbolic surface of revolution.

23. The NA conversion device of claim 21, wherein:

said primary reflector comprises at least a portion of a substantially hyperbolic surface of revolution; and

said secondary reflector comprises at least a portion of a substantially elliptical surface of revolution.

24. The conversion device of claim 21, wherein:

a corner of said primary reflector is truncated along a plane substantially parallel to said first optical axis.

25. The conversion device of claim 21, wherein:

a corner of said secondary reflector is truncated along a plane substantially parallel to said second optical axis.

26. The NA conversion device of claim 18, comprising further a retro-reflector disposed opposite said reflector to reflect at least a portion of the electromagnetic radiation that does not impinge directly on said reflector toward said reflector through the first focal point of said reflector to increase the flux intensity of the converging rays.

27. The NA conversion device of claim 26, wherein said retro-reflector comprises a spherical retro-reflector disposed on a side of said source opposite said primary reflector to reflect electromagnetic radiation emitted from said source in a direction away from said primary reflector toward said primary reflector through the first focal point of said primary reflector.

28. The NA conversion device of claim 18, comprising further:

a second light pipe having an input surface and an output surface, said input surface of said second light pipe disposed proximate to said output end of said TLP to collect and transmit substantially all of said radiation;

a primary reflector disposed proximate to said output surface of said second light pipe, said primary reflector transmitting a first band of said radiation and reflecting a second and third bands of said radiation;

a secondary reflector disposed proximate to said output surface of said second light pipe, said secondary reflector transmitting said second band of said radiation and reflecting said first and third bands of said radiation; and

a third reflector disposed proximate to said output surface of said second light pipe, said third reflector transmitting said third band of said radiation and reflecting said first and second bands of said radiation.

29. The NA conversion device of claim 28, wherein said input surface is substantially larger than said output end.

30. The NA conversion device of claim 29, wherein said input surface is substantially twice as large as said output end.

31. The NA conversion device of claim 29, wherein said input surface comprises a first area coextensive with said output end;

a second area not coextensive with said output end; and

wherein said second area is coated with a reflective coating.

32. The NA conversion device of claim 29, wherein said input surface comprises a first area coextensive with said output end;

a second area not coextensive with said output end; and

wherein a wave-plate is disposed proximate to said second area;

said wave-plate being coated with a reflective coating.

33. The NA conversion device of claim 28, wherein:

said. output end has a first dimension and a second dimension, said second dimension being substantially orthogonal to said first dimension;

said input surface has a third dimension and a fourth dimension, said third dimension being substantially orthogonal to said fourth dimension;

said first dimension is substantially equal to said third dimension; and

said fourth dimension is substantially twice said second dimension.

34. The NA conversion device of claim 28, wherein said output surface comprises a first, second, and third areas;

and

said primary reflector is a first reflective coating over said first area;

said secondary reflector is a second reflective coating over said second area; and

said third reflector is a third reflective coating over said third area.

35. The NA conversion device of claim 28, comprising further a color wheel rotatably mounted on a shaft and having a surface comprising a first, second, and third areas disposed spirally about said shaft;

and

wherein all of said input surface is substantially transmissive;

said primary reflector is a first reflective coating over said first area;

said secondary reflector is a second reflective coating over said second area; and

said third reflector is a third reflective coating over said third area.

36. The NA conversion device of claim 28, wherein said second light pipe is selected from the group consisting of:

an SLP, and

a TLP.

37. The NA conversion device of claim 28, wherein said second light pipe is substantially hollow.

38. The NA conversion device of claim 28, wherein a substantially anti-reflective coating is disposed on said input surface.

39. The NA conversion device of claim 28, wherein a substantially anti-reflective coating is disposed on said output surface.

40. The NA conversion device of claim 28, wherein said output surface is substantially convex.

41. The NA conversion device of claim 28, comprising further:

a reflective polarizer disposed proximate said output surface, said reflective polarizer collecting and polarizing substantially all of said radiation into a first polarization and a second polarization;

wherein said radiation of said first polarization is transmitted; and

radiation of said second polarization is reflected toward said output surface.

42. The light recovery apparatus of claim 41, wherein said reflective polarizer comprises a wire-grid polarizer.