Immersed dichroic optical relay

1. An optical element comprising:

a refractive material;

a plurality of relay curvatures formed in the refractive material; and

dichroic relay mirrors configured as an optical relay, the dichroic relay mirrors including a dichroic reflective layer disposed on the plurality of relay curvatures and immersed in the refractive material, wherein the dichroic reflective layer reflects a first non-visible spectrum light and passes light outside the first non-visible spectrum light.

2. The optical element of claim 1 , wherein the optical relay is an afocal optical relay configured to receive an image having the first non-visible spectrum light at an entrance pupil of the optical relay and output the image at an exit pupil of the optical relay.

3. The optical element of claim 2 , wherein the plurality of relay curvatures includes a first spherical curvature and a second spherical curvature aligned concentrically with the first spherical curvature, wherein the first spherical curvature has a first radius smaller than a second radius of the second spherical curvature.

4. The optical element of claim 2 , wherein the plurality of relay curvatures includes conical surfaces.

5. The optical element of claim 4 , wherein the plurality of relay curvatures includes two parabolic surfaces and two hyperbolic surfaces.

6. The optical element of claim 1 further comprising:

a first refractive microlens disposed at an entrance pupil of the optical relay; and

a second refractive microlens disposed at an exit pupil of the optical relay.

7. The optical element of claim 6 , wherein a first lensing surface of the first refractive microlens is formed in the refractive material.

8. The optical element of claim 1 , wherein the dichroic reflective layer includes a plurality of dielectric layers.

9. The optical element of claim 1 , wherein the first non-visible spectrum light is near-infrared light received from an ambient light source.

10. A head mounted display (HMD) comprising:

a frame;

an infrared source configured to emit infrared light in an eyeward direction;

an optical combiner including a refractive material secured to the frame, wherein the optical combiner includes an optical relay having an entrance pupil coupled to receive reflected infrared light reflected by an eye of a wearer of the HMD, wherein the optical relay includes a plurality of relay curvatures formed in the refractive material and dichroic relay mirrors including a dichroic reflective layer disposed on the plurality of relay curvatures and immersed in the refractive material, wherein the dichroic reflective layer is a hot mirror that reflects the infrared light and passes visible light; and

an image sensor coupled to receive an image from an exit pupil of the optical relay.

11. The HMD of claim 10 further comprising:

a display for generating display light, wherein the display is included in the frame; and

a display waveguide included in the optical combiner, wherein the display waveguide is configured to receive the display light and direct the display light in the eyeward direction.

12. The HMD of claim 10 , wherein the optical combiner further includes a second optical relay having a second entrance pupil coupled to receive the reflected infrared light, the second optical relay including a second plurality of relay curvature formed in the refractive material and second dichroic relay mirrors including the dichroic reflective layer disposed on the second plurality of relay curvatures immersed in the refractive material.

13. The HMD of claim 12 further comprising:

a second image sensor coupled to receive a second image from a second exit pupil of the second optical relay.

14. The HMD of claim 10 , further comprising:

a first refractive microlens disposed near the entrance pupil of the optical relay; and

a second refractive microlens disposed near the exit pupil of the optical relay and the image sensor.

15. The HMD of claim 14 , wherein a first lensing surface of the first refractive microlens is formed in the refractive material.

16. The HMD of claim 10 , wherein the infrared source is included in the optical combiner.

17. The HMD of claim 10 , wherein the infrared source is disposed within the frame.

18. The HMD of claim 10 , wherein the image sensor includes a filter to block the visible light from image pixels of the image sensor.

19. A system comprising:

an optical relay coupled to receive an image having a near-infrared light spectrum at an entrance pupil of the optical relay and output the image at an exit pupil of the optical relay, the optical relay including:

a refractive material;

a plurality of relay curvatures formed in the refractive material; and

dichroic relay mirrors configured as the optical relay, the dichroic relay mirrors including a dichroic reflective layer disposed on the plurality of relay curvatures and immersed in the refractive material, wherein the dichroic reflective layer reflects the near-infrared light spectrum of the image and passes light outside the near-infrared light spectrum; and

an image sensor coupled to receive the image from the exit pupil.

20. The HMD of claim 10 , wherein the image is an infrared image, and wherein the image sensor is configured to receive the infrared light emitted by the infrared source and directed to the image sensor via the dichroic relay mirrors, the image sensor also configured to block visible light wavelengths from image pixels of the image sensors.