Polarization recovery system using light pipes

• US 20030179977A1
• Filed: 02/10/2003
• Published: 09/25/2003
• Est. Priority Date: 02/08/2002
• Status: Active Grant

• Current Assignee: Wavien, Inc.
• Original Assignee: Wavien, Inc.
• Inventors: Li, Kenneth K.
• Granted Patent: US 6,836,576 B2
• Time in Patent Office: Days
• US Class Current: 385/11
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 6/105 having optical polarisation effects
• 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

Abstract

A polarization recovery system using light pipes has a reflector having a first and a second focal points. A source of electromagnetic radiation is disposed proximate to the first focal point of the reflector to emit rays of light that reflect from the reflector and converge substantially at the second focal point. A light pipe having an input surface with a first transmissive portion disposed proximate to the second focal point and a second reflective portion disposed distal to the second focal point and an output surface collects and transmits substantially all of the light. The output surface has a radius of curvature substantially equal to a length of the light pipe, a first focal area proximate to the first transmissive portion and a second focal area proximate to the second reflective portion. A polarizer applied to the output surface transmits the light of a first polarization and reflects the light of a second polarization toward the second reflective area, and the light of the second polarization is substantially reflected by the second reflective area toward the output surface.

Claims

1. A polarization recovery system using light pipes comprising:

a light pipe having an input surface and an output surface, said input surface having a first transmissive portion and a second reflective portion;

said output surface having a radius of curvature substantially equal to a length of said light pipe, a first focal area proximate to said first transmissive portion, and a second focal area proximate to said second reflective portion;

a polarizer applied to said output surface, said polarizer transmitting a light of a first polarization and reflecting a light of a second polarization toward said second reflective portion; and

wherein said light of said second polarization is substantially reflected by said second reflective portion toward said output surface.

2. The polarization recovery system of claim 1, comprising further:

a reflector having a first and a second focal points;

a source of electromagnetic radiation disposed proximate to said first focal point of said reflector to emit rays of light that reflect from said reflector and converge substantially at said second focal point;

wherein said first transmissive portion is disposed proximate to said second focal point to collect and transmit substantially all of said light.

3. The polarization recovery system of claim 2, wherein said reflector comprises at least a portion of a substantially elliptical surface of revolution.

4. The polarization recovery system of claim 2, wherein said reflector comprises at least a portion of a substantially spherical surface of revolution.

5. The polarization recovery system of claim 2, wherein said reflector comprises at least a portion of a substantially toric surface of revolution.

6. The polarization recovery system 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 light reflect from said primary reflector toward said secondary reflector and converge substantially at said second focal point.

7. The polarization recovery system of claim 6, wherein said primary and secondary reflectors each comprise at least a portion of a substantially elliptical surface of revolution.

8. The polarization recovery system of claim 6, wherein said primary and secondary reflectors each comprise at least a portion of a substantially parabolic surface of revolution.

9. The polarization recovery system of claim 6, 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.

10. The polarization recovery system of claim 6, 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.

11. The polarization recovery system of claim 2, wherein said reflector has a coating that reflects only a pre-specified portion of the electromagnetic radiation spectrum.

12. The polarization recovery system of claim 11, wherein said pre-specified portion is selected from the group consisting of:

infrared light,

visible light,

a pre-specified band of wavelengths of light,

a specific color of light, and

a combination thereof.

13. The polarization recovery system of claim 2, further comprising a retro-reflector disposed on a side of said source opposite said reflector.

14. The polarization recovery system of claim 13, wherein said retro-reflector comprises a spherical retro-reflector.

15. The polarization recovery system of claim 13, wherein said retro-reflector has a coating that reflects only a pre-specified portion of the electromagnetic radiation spectrum.

16. The polarization recovery system of claim 13, wherein said pre-specified portion is selected from the group consisting of:

infrared light,

visible light,

a pre-specified band of wavelengths of light,

a specific color of light, and

a combination thereof.

17. The polarization recovery system of claim 13, wherein said coating transmits light selected from the group consisting of:

infrared light, and

ultraviolet light.

18. The polarization recovery system of claim 2, wherein said source of electromagnetic radiation is selected from the group consisting of:

a single-chip;

a double-chip; and

a triple-chip.

19. The polarization recovery system of claim 2, wherein said source of electromagnetic radiation comprises an arc lamp.

20. The polarization recovery system of claim 19, wherein said arc lamp comprises a lamp selected from the group consisting of a xenon lamp, a metal halide lamp, a UHP lamp, a HID lamp, or a mercury lamp.

21. The polarization recovery system of claim 2, wherein said source of electromagnetic radiation is selected from the group consisting of a halogen lamp, and a filament lamp.

22. The polarization recovery system of claim 2, comprising further:

an image projection system disposed proximate to said output surface to collect substantially all of said light.

23. The polarization recovery system of claim 22, wherein said image projection system is selected from the group consisting of:

an LCOS imager,

a DMD chip, and

a transmissive LCD panel.

24. The polarization recovery system of claim 2, comprising further:

an input light pipe disposed between said second focal point and said first transmissive portion, said input light pipe having an entrance surface disposed proximate to said second focal point to collect and transmit substantially all of said light and an exit surface disposed proximate to said first transmissive portion to emit substantially all of said light.

25. The polarization recovery system of claim 24, wherein said input light pipe is selected from the group consisting of:

an SLP, and

a TLP.

26. The polarization recovery system of claim 2, wherein a shape of said first transmissive portion is matched substantially to an aperture of said source of light.

27. The polarization recovery system of claim 1, wherein said light pipe is hollow;

and

said first transmissive portion comprises an aperture;

said output surface comprises a plano-convex lens; and

wherein said polarizer is applied to a planar surface of said lens.

28. The polarization recovery system of claim 27, wherein an inner surface of said light pipe is coated with a polarization preserving material.

29. The polarization recovery system of claim 27, comprising further a retardation plate disposed in an interior of said light pipe in a path of said light of said second polarization to rotate a polarization of said light.

30. The polarization recovery system of claim 29, wherein said retardation plate is selected from the group consisting of a quarter-wave plate, a half-wave plate and harmonics thereof.

31. The polarization recovery system of claim 1, wherein said second reflective area comprises further a wave plate to rotate said light of said second polarization to said first polarization.

32. The polarization recovery system of claim 1, wherein a curvature of said output surface is selected from the group consisting of cylindrical and spherical.

33. The polarization recovery system of claim 1, wherein said polarizer comprises a wire-grid polarizer.

34. The polarization recovery system of claim 1, wherein a shape of said first transmissive portion is selected from the group consisting of circular, oval, elliptical, octagonal, triangular, and rectangular.

35. The polarization recovery system of claim 1, wherein said light pipe is comprised of a material selected from the group consisting of quartz, glass, plastic, or acrylic.

36. The polarization recovery system of claim 1, wherein said light pipe is selected from the group consisting of:

an SLP, and

a TLP.

37. A method of polarization recovery comprising the steps of:

positioning a source of electromagnetic radiation at a first focal point of a reflector;

producing rays of light by said source;

reflecting a portion of said rays of light by said reflector toward a second focal point;

converging substantially said rays of light at said second focal point;

positioning an output light pipe having an input surface and an output surface so a first transmissive portion of said input surface is substantially proximate to said second focal point;

collecting substantially said rays of light at said first transmissive portion;

passing said rays of light through said output light pipe to said output surface;

positioning a polarizer proximate to said output surface;

polarizing substantially said rays of light into light of a first polarization and light of a second polarization;

transmitting substantially said light of said first polarization;

reflecting substantially said light of said second polarization through said light pipe toward a second reflective portion of said input surface;

circularly polarizing substantially said light of said second polarization with a wave plate;

reflecting substantially said circularly polarized light toward said output surface;

passing said circularly polarized light through said output light pipe;

polarizing substantially said circularly polarized light into light of said first polarization; and

outputting substantially light of said first polarization from said output surface of said output light pipe.