Multi-stage optical waveguide for a luminaire
According to one aspect, an optical waveguide includes a first waveguide portion and a second waveguide portion adjacent to and separate from the first waveguide portion. The waveguide portions include light coupling portions that are at least partially aligned and adapted to receive light developed by a light source. The first waveguide portion further has a first major surface with light direction features and a second major surface opposite the first major surface. The second waveguide portion further has a third major surface proximate the second major surface with an air gap disposed therebetween and a fourth major surface opposite the third major surface wherein the fourth major surface includes a cavity extending therein.
1. An optical waveguide, comprising:
a plurality of waveguide portions arranged in a stack;
each waveguide portion having a coupling surface, a surface opposite the coupling surface and an exterior surface extending between the coupling surface and the surface opposite the coupling surface;
wherein the coupling surface of a first waveguide portion of the plurality of waveguide portions is aligned with a light source and is configured to receive light developed by the light source and to redirect a first portion of the light to the surface opposite the coupling surface and a second portion of the light to the exterior surface such that the second portion of light is emitted from the optical waveguide from the exterior surface; and
wherein the plurality of waveguide portions are aligned such that light escaping through the surface opposite the coupling surface of one waveguide portion of the plurality of waveguide portions is received by the coupling surface of an adjacent waveguide portion of the plurality of waveguide portions.
2. The optical waveguide of claim 1 , wherein each of the plurality of waveguide portions are substantially identical.
3. The optical waveguide of claim 1 , wherein each of the plurality of waveguide portions are cylindrical.
4. The optical waveguide of claim 1 , wherein each of the plurality of waveguide portions has a cavity disposed in the coupling surface.
5. The optical waveguide of claim 4 , wherein the cavity of at least one of the plurality of waveguide portions has a parabolic shape, a frustum shape, a conical shape, an elliptic paraboloid shape, a frustoconical shape, or a combination of such shapes.
6. The optical waveguide of claim 1 , wherein substantially all of the light is extracted from the optical waveguide through the exterior surfaces.
7. The optical waveguide of claim 6 , wherein the exterior surface of each of the plurality of waveguide portions diffuses light.
8. The optical waveguide of claim 1 , wherein the exterior surface of each of the plurality of waveguide portions has at least one of a roughened surface, a scatter coated surface and a textured surface.
9. A light engine comprising:
a plurality of waveguide stages, each of the plurality of waveguide stages comprising a coupling surface, a light re-direction feature, a surface opposite to the coupling surface and an exterior surface extending between the coupling surface and the surface opposite to the coupling surface where the coupling surface receives light, wherein the redirection feature directs a first portion of the light from the waveguide stage through the surface opposite to the coupling surface and redirects a second portion of the light to the exterior surface, the exterior surface emitting light from the waveguide stage;
the plurality of waveguide stages arranged in a stack such that the surface opposite to the coupling surface of one of the waveguide stages is arranged opposite the coupling surface of an adjacent one of the plurality of waveguide stages; and
a light source for directing light into the coupling surface of a first one of the plurality of waveguide stages.
10. The light engine of claim 9 wherein the plurality of waveguide stages comprises at least three waveguide stages.
11. The light engine of claim 9 wherein the plurality of waveguide stages comprises at least five waveguide stages.
12. The light engine of claim 9 wherein each of the plurality of waveguide stages is generally cylindrical in shape and the plurality of waveguide stages are axially aligned.
13. The light engine of claim 9 wherein the re-direction feature comprises a cavity that creates an air gap.
14. The light engine of claim 13 wherein the cavity has a cross-sectional shape comprising a V-shape, a parabolic shape, a frustum shape, a conical shape, an elliptic paraboloid shape or a combination of such shapes.
15. The light engine of claim 9 wherein the re-direction features collimate the second portion of the light.
16. The light engine of claim 9 wherein the exterior surface, the coupling surface and the re-direction feature are polished.
17. The light engine of claim 9 wherein the exterior surface is diffusive.
18. The light engine of claim 9 wherein the light source is contained in a base, the base comprising a heatsink.
19. A luminaire comprising:
an optical waveguide comprising:
a plurality of waveguide stages, each of the plurality of waveguide stages comprising a coupling surface, a light re-direction feature, a surface opposite to the coupling surface and an exterior surface extending between the coupling surface and the surface opposite to the coupling surface where the coupling surface receives light, the redirection feature directs a first portion of the light from the waveguide stage through the surface opposite to the coupling surface and redirects a second portion of the light to the exterior surface, the exterior surface emitting light from the waveguide stage;
the plurality of waveguide stages arranged in a stack such that the surface opposite to the coupling surface of one of the waveguide stages is arranged opposite the coupling surface of an adjacent one of the plurality of waveguide stages;
at least one LED for directing light into the coupling surface of a first one of the plurality of waveguide stages; and
a housing surrounding the optical waveguide.