LED homogenizer

1. An optical system comprising:

a homogenizer configured to emit light that has a half angle that is at least 80% of a half angle of light entering the homogenizer, the homogenizer comprising:

an entrance face positioned to receive light from a source, the entrance face having a first shape;

a body configured to homogenize light received through the entrance face by reflecting the light a plurality of times off sidewalls of the body; and

an exit face configured to emit light, the exit face parallel to the entrance face; and

an imaging high numerical aperture optical system coupled to the exit face of the homogenizer.

2. The system of claim 1 , wherein the entrance face and exit face have approximately a same area.

3. The system of claim 1 , wherein the exit face has an area at least equal to

n

2

⁢

A

⁢

⁢

Ω

n

′2

⁢

Ω

′

wherein Ω is an effective solid angle in which light enters the homogenizer, Ω′ is the effective solid angle whereby light leaves the homogenizer, A is the area of the entrance face, n is a refractive index of a medium from which light is received by the homogenizer, n′ is a refractive index of material into which the homogenizer emits.

4. The system of claim 1 , wherein the exit face has an area at least equal to

n

2

⁢

A

⁢

⁢

π

n

′2

⁢

Ω

′

wherein 106 ′ is an effective solid angle whereby light leaves the homogenizer, A is the area of the entrance face, n is a refractive index of a medium from which light is received by the homogenizer, n′ is a refractive index of a material into which the homogenizer emits.

5. The system of claim 1 , wherein the body is tapered outward from the entrance face.

6. The system of claim 5 , wherein the exit face has a second shape different than the first shape and the homogenizer comprises a set of transition features transitioning from the first shape to the second shape.

7. The system of claim 6 , wherein the transition features comprise a set of sidewall facets transitioning to the second shape.

8. The system of claim 7 , wherein the second shape has a surface area greater than or equal to a surface area of the first shape.

9. The system of claim 7 , wherein the set of sidewall facets comprises a first set of facets corresponding to an extruded cut of the first shape, the cut tapering outward according to a first taper angle.

10. The system of claim 9 , wherein the set of sidewall facets comprise a second set of facets corresponding to an extruded cut of a third shape tapering outward according to a second taper angle.

11. The system of claim 1 , wherein the homogenizer is formed of at least one of plastic, PMMI, glass and silicone.

12. The system of claim 1 , wherein the high numerical aperture optical system comprises an imaging multi-element optical stack comprising a series of lenses optically coupled to the exit face of the homogenizer, wherein a first lens of the series of lenses is directly coupled to the exit face of the homogenizer, the lenses in the series of lenses configured, in combination, to successively reduce a beam angle of light from a first beam angle to an emission beam angle and emit in an emission beam angle at least 70% of the light entering the series of lenses from the homogenizer.

13. The system of claim 1 , wherein the imaging high numerical aperture optical system comprises an optical device configured to emit at least 70% of the light entering the optical device from the homogenizer in a controlled beam angle.

14. The system of claim 1 , further comprising an encapsulant contacting the entrance face and wherein the imaging high numerical optical aperture system comprises a lens having a same index of refraction as the encapsulant.

15. The system of claim 1 , wherein the exit face is a virtual exit face.

16. The system of claim 1 , wherein the exit face is physical exit face.

17. A method of homogenizing light, comprising:

receiving light at an entrance face of a homogenizer, the entrance face having a first shape;

homogenizing light received through the entrance face by reflecting the light a plurality of times in the homogenizer; and

emitting homogenized light from an exit face of the homogenizer that is parallel to the entrance face of the homogenizer, the light emitted with a half angle that is at least 80% of the half angle of light entering the homogenizer into an imaging high numerical aperture system coupled to the exit face of the homogenizer.

18. The method of claim 17 , wherein light is emitted from the exit face in a second shape different than the first shape.

19. The method of claim 17 , wherein the high numerical aperture imaging system comprises a series of lenses that are configured, in combination, to successively reduce a beam angle of light from a first beam angle to an emission beam angle and emit in an emission beam angle at least 70% of the light entering the series of lenses from the homogenizer.

20. The method of claim 17 , wherein the high numerical aperture imaging system is configured to emit in a controlled beam angle at least 70% of the light received from the homogenizer.

21. The method of claim 17 , wherein:

the exit face has a second shape; and

the homogenizer further comprises:

a first set of sidewall facets corresponding to the first shape tapered outward at a first taper angle relative to an axis running from the entrance face to the exit face; and

a second set of sidewall facets corresponding to a third shape, the second set of facets tapered outward at a second taper angle relative to the axis.

22. The method of claim 21 , wherein the entrance face is square and the exit face is circular.