Transparent illumination layer with transparent waveguide structure

1. A head mounted device, comprising:

a frame;

a near-infrared light source coupled with the frame, wherein the near-infrared light source is configured to emit near-infrared light; and

an optical element secured to the frame, wherein the optical element includes:

a transparent layer;

a plurality of outcoupling elements distributed across the transparent layer; and

a transparent waveguide structure configured to receive the near-infrared light from the near-infrared light source coupled with the frame, wherein the transparent waveguide structure includes a plurality of optical fibers configured to respectively deliver the near-infrared light from the near-infrared light source to the plurality of outcoupling elements, wherein the outcoupling elements are configured to outcouple the near-infrared light as near-infrared illumination light to illuminate an eye region with patterned near-infrared illumination light, and wherein optical path lengths of the plurality of optical fibers to the respective plurality of outcoupling elements are approximately equal so as to homogenize a brightness output of the plurality of outcoupling elements.

2. The head mounted device of claim 1 , wherein each of the plurality of optical fibers of the transparent waveguide structure has a transparent core and a transparent clad layer.

3. The head mounted device of claim 2 , wherein the outcoupling elements are less than 75 microns across and unnoticeable to observers of the head mounted device, and wherein each of the plurality of optical fibers of the transparent waveguide structure is less than 10 microns wide.

4. The head mounted device of claim 1 , further comprising:

an input coupler configured to incouple the near-infrared light emitted by the non-visible light source into the transparent waveguide structure;

a first backside reflector configured to reflect stray near-infrared light back to the input coupler so as to be incoupled into the transparent waveguide structure; and

a second backside reflector configured to outcouple stray near-infrared illumination light back to at least one of the outcoupling elements so as to be directed toward the eye region.

5. An optical system, comprising:

a non-visible light source configured to emit non-visible light;

a transparent layer;

a plurality of outcoupling elements positioned across the transparent layer; and

a waveguide structure that includes a plurality of optical fibers configured to respectively deliver the non-visible light from the non-visible light source to the plurality of outcoupling elements, wherein the outcoupling elements are configured to outcouple the non-visible light as non-visible illumination light to illuminate an eye region, and wherein optical path lengths of the plurality of optical fibers, from the non-visible light source to the respective plurality of outcoupling elements, are varied so as to adjust a brightness output of the plurality of outcoupling elements due to optical losses in the waveguide structure.

6. The optical system of claim 5 , wherein a first outcoupling element in the plurality of outcoupling elements is configured to outcouple the non-visible illumination light as a first light cone having a first divergence angle, and wherein a second outcoupling element in the plurality of outcoupling elements is configured to outcouple the non-visible illumination light as a second light cone having a second divergence angle that is different than the first divergence angle.

7. The optical system of claim 5 , wherein each of the plurality of optical fibers of the waveguide structure includes a transparent dielectric material to confine the non-visible light to the waveguide structure.

8. The optical system of claim 5 , wherein a material used for the waveguide structure is transparent to visible light.

9. The optical system of claim 5 , wherein the waveguide structure follows an indirect curving path between the non-visible light source and the plurality of outcoupling elements.

10. The optical system of claim 5 , wherein the non-visible light source includes at least one of a laser source, a superluminescent light emitting diode (S-LED), a vertical-cavity surface-emitting laser (VCSEL), or an integrated laser array.

11. The optical system of claim 5 , wherein at least a portion of the outcoupling elements are less than 75 microns, and wherein each of the plurality of optical fibers of the transparent waveguide structure is less than 10 microns wide.

12. The optical system of claim 5 , further comprising:

an input coupler configured to incouple the non-visible light emitted by the non-visible light source into the waveguide structure;

a first backside reflector configured to reflect stray non-visible light back to the input coupler so as to be incoupled into the waveguide structure; and

a second backside reflector configured to outcouple stray non-visible illumination light back to at least one of the outcoupling elements so as to be directed toward the eye region.

13. The optical system of claim 12 , wherein the second backside reflector includes at least one of a metal layer or a Bragg reflector.

14. The optical system of claim 5 , wherein the outcoupling elements include an output grating and a beam-shaping element.

15. The optical system of claim 5 , wherein the outcoupling elements are in a field of view (FOV) of an eye of a user of the optical system.

16. The optical system of claim 5 , wherein the non-visible light source is a first non-visible light source, wherein the non-visible light is first non-visible light, wherein the plurality of outcoupling elements is a first plurality of outcoupling elements, wherein the waveguide structure is a first waveguide structure, and wherein the optical system further comprises:

a second non-visible light source configured to emit second non-visible light;

a second plurality of outcoupling elements positioned across the transparent layer; and

a second waveguide structure configured to deliver the second non-visible light to the second plurality of outcoupling elements, wherein the second plurality of outcoupling elements is configured to outcouple the second non-visible light as the non-visible illumination light to illuminate the eye region.

17. A near-eye optical element comprising:

a transparent layer;

an outcoupling element disposed with the transparent layer;

a transparent waveguide structure configured to confine near-infrared light received from a near-infrared light source, wherein the transparent waveguide structure is configured to deliver the near-infrared light to the outcoupling element, and wherein the outcoupling element is configured to outcouple the near-infrared light as patterned near-infrared illumination light to illuminate an eye region, and

at least one backside reflector configured to reflect stray near-infrared light so as to incouple the stray near-infrared light into the transparent waveguide structure, or reflect stray near-infrared light back to the outcoupling element so as to be directed toward the eye region.

18. The near-eye optical element of claim 17 , wherein the outcoupling element is less than 75 microns, and wherein the transparent waveguide structure is less than 10 microns wide.

19. The near-eye optical element of claim 17 , wherein the outcoupling element is an individual outcoupling element amongst a plurality of outcoupling elements, wherein the transparent waveguide structure includes a plurality of optical fibers configured to respectively deliver the near-infrared light from the near-infrared light source to the plurality of outcoupling elements, and wherein optical path lengths of the plurality of optical fibers to the respective plurality of outcoupling elements are approximately equal so as to homogenize a brightness output of the plurality of outcoupling elements.

20. The near-eye optical element of claim 17 , wherein the outcoupling element is an individual outcoupling element amongst a plurality of outcoupling elements, wherein the transparent waveguide structure includes a plurality of optical fibers configured to respectively deliver the near-infrared light from the near-infrared light source to the plurality of outcoupling elements, and wherein optical path lengths of the plurality of optical fibers, from the near-infrared light source to the respective plurality of outcoupling elements, are varied so as to adjust a brightness output of the plurality of outcoupling elements due to optical losses in the transparent waveguide structure.