Superimposed diffraction gratings for eyepieces
Embodiments of the present disclosure are directed to techniques for manufacturing an eyepiece (or eyepiece layer) by applying multiple, different diffraction gratings to a single side of an eyepiece substrate instead of applying different gratings to different sides (e.g., opposite surfaces) of the substrate. Embodiments are also directed to the eyepiece (or eyepiece layer) that is arranged to have multiple, different diffraction gratings on a single side of the eyepiece substrate. In some embodiments, two or more grating patterns are superimposed to create a combination pattern in a template (e.g., a master), which is then used to apply the combination pattern to a single side of the eyepiece substrate. In some embodiments, multiple layers of patterned material (e.g., with differing refraction indices) are applied to a single side of the substrate. In some examples, the combined grating patterns are orthogonal pupil expander and exit pupil expander grating patterns.
1. A waveguide comprising:
a substrate; and
an imprinted pattern on a side of the substrate, wherein the imprinted pattern comprises:
a first zone comprising a first grating structure; and
a second zone comprising a second grating structure, wherein the first zone is between the substrate and the second zone, wherein the second grating structure differs from the first grating structure, and wherein the first zone comprises an orthogonal pupil expander (OPE) and the second zone comprises an exit pupil expander (EPE).
2. The waveguide of claim 1 , wherein the first zone further comprises an incoupling grating (ICG) configured to receive light from a projector.
3. The waveguide of claim 2 , wherein the ICG is further configured to alter propagation angles of the light such that the light can travel through the waveguide by total internal reflection toward the second zone.
4. The waveguide of claim 1 , wherein the first zone comprises line gratings.
5. The waveguide of claim 1 , wherein the second zone comprises pillars or holes.
6. The waveguide of claim 1 , wherein the waveguide is configured such that internally reflected light travels through the OPE and is coupled out toward the EPE.
7. The waveguide of claim 6 , wherein the OPE and the EPE are in superposition on the side of the substrate.
8. The waveguide of claim 7 , wherein the first zone comprises a first material, the second zone comprises a second material, wherein a refractive index of the first material exceeds a refractive index of the second material.
9. The waveguide of claim 8 , wherein a difference between the refractive index of the first material and the refractive index of the second material is at least 0.2.
10. The waveguide of claim 1 , wherein the imprinted pattern further comprises a third zone comprising a third grating structure, wherein the second zone is between the first zone and the third zone.
11. The waveguide of claim 10 , wherein the second zone comprises pillars or holes configured to divide and redirect at least a portion of light from the first zone and to spread and to multiply the light within a plane of the waveguide toward the third zone.
12. The waveguide of claim 10 , wherein the third zone comprises line gratings and holes.
13. The waveguide of claim 1 , wherein the first zone comprises a first material, the second zone comprises a second material, and a refractive index of the substrate exceeds a refractive index of the first material and a refractive index of the second material.
14. The waveguide of claim 1 , wherein the substrate is glass, the first zone is a first patterned polymer grating, and the second zone is a second patterned polymer grating.
15. An eyepiece comprising the waveguide of claim 1 .
16. A virtual reality or augmented reality apparatus comprising the eyepiece of claim 15 .
17. A waveguide comprising:
a substrate; and
an imprinted pattern on a side of the substrate, wherein the imprinted pattern comprises:
a first zone comprising a first grating structure;
a second zone comprising a second grating structure, wherein the first zone is between the substrate and the second zone, and wherein the second grating structure differs from the first grating structure; and
a third zone comprising a third grating structure, wherein the second zone is between the first zone and the third zone, and wherein the third zone comprises a combined orthogonal pupil expander (OPE)/exit pupil expander (EPE) grating structure.
18. The waveguide of claim 17 , wherein the second zone comprises pillars or holes configured to divide and redirect at least a portion of light from the first zone and to spread and to multiply the light within a plane of the waveguide toward the third zone.
19. The waveguide of claim 17 , wherein the third zone comprises line gratings and holes.
20. An eyepiece comprising the waveguide of claim 17 .
21. A virtual reality or augmented reality apparatus comprising the eyepiece of claim 20 .
22. A waveguide comprising:
a substrate; and
an imprinted pattern on a side of the substrate, wherein the imprinted pattern comprises:
a first zone comprising a first grating structure;
a second zone comprising a second grating structure, wherein the first zone is between the substrate and the second zone, and wherein the second grating structure differs from the first grating structure; and
a third zone comprising a third grating structure, wherein the second zone is between the first zone and the third zone, and wherein the first zone comprises a first material, the second zone comprises a second material, the third zone comprises a third material, and a refractive index of the second material exceeds a refractive index of the third material.
23. The waveguide of claim 22 , wherein the second zone comprises pillars or holes configured to divide and redirect at least a portion of light from the first zone and to spread and to multiply the light within a plane of the waveguide toward the third zone.
24. The waveguide of claim 22 , wherein the third zone comprises line gratings and holes.
25. An eyepiece comprising the waveguide of claim 22 .
26. A virtual reality or augmented reality apparatus comprising the eyepiece of claim 25 .