Near-eye display system having optical combiner
An optical waveguide is provided. The optical waveguide includes a base structure and a plurality of grating structures disposed at the base structure. The grating structures include a plurality of in-coupling grating structures configured to couple a plurality of lights into the optical waveguide. At least one of a grating period or a slant angle of a first in-coupling grating structure is different from at least one of a corresponding grating period or a corresponding slant angle of a second in-coupling grating structure. The grating structures also include a plurality of out-coupling grating structures configured to couple the lights out of the optical waveguide.
1. An optical combiner, comprising:
a first substrate and a second substrate;
a base structure disposed between the first substrate and the second substrate; and
a plurality of grating structures disposed at the base structure and comprising:
a plurality of in-coupling grating structures configured to couple a plurality of lights into the optical combiner, wherein at least one of a grating period or a slant angle of a first in-coupling grating structure is different from at least one of a corresponding grating period or a corresponding slant angle of a second in-coupling grating structure; and
a plurality of out-coupling grating structures configured to couple the lights out of the base structure along a longitudinal direction of the base structure,
wherein spatial distribution of the in-coupling grating structures along the longitudinal direction of the base structure overlaps with spatial distribution of the out-coupling grating structures along the longitudinal direction of the base structure.
2. The optical combiner of claim 1 , wherein:
for at least one of the in-coupling grating structures that couples a light into the base structure, a set of two or more out-coupling grating structures are configured to couple the light out of the base structure, and
the two or more out-coupling grating structures have at least one of a same grating period or a same slant angle.
3. The optical combiner of claim 1 , wherein the base structure comprises a photopolymer material.
4. The optical combiner of claim 3 , wherein the plurality of grating structures comprise a plurality of volume holographic grating structures recorded in the photopolymer material.
5. The optical combiner of claim 1 , wherein the plurality of grating structures comprise at least one of a volume holographic grating structure or a surface relief grating structure.
6. The optical combiner of claim 1 , wherein grating periods of at least two of the plurality of in-coupling grating structures are different.
7. The optical combiner of claim 1 , wherein slant angles of at least two of the plurality of in-coupling grating structures are different.
8. The optical combiner of claim 1 , wherein the grating structures are disposed at at least one of a top surface or a bottom surface of the base structure.
9. The optical combiner of claim 1 , wherein at least a portion of the plurality of grating structures is provided at at least one of a surface of the first substrate facing the base structure, a surface of the first substrate facing against the base structure, a surface of the second substrate facing the base structure, or a surface of the second substrate facing against the base structure.
10. The optical combiner of claim 1 , wherein at least a portion of the plurality of grating structures is provided at least partially inside at least one of the first substrate or the second substrate.
11. The optical combiner of claim 1 , wherein
the base structure comprises a first base structure and a second base structure,
the plurality of in-coupling grating structures are provided at the first base structure, and
the plurality of out-coupling grating structures are provided at the second base structure.
12. The optical combiner of claim 11 , further comprising:
a center substrate,
wherein the first base structure is disposed between the first substrate and the center substrate, and
wherein the second base structure is disposed between the center substrate and the second substrate.
13. An optical device, comprising:
a display configured to generate a plurality of image lights; and
an optical combiner coupled with the display and configured to guide the image lights generated by the display to an eye-box of the optical device, the optical combiner comprising:
a first substrate and a second substrate;
a base structure disposed between the first substrate and the second substrate; and
a plurality of grating structures disposed at the base structure and comprising:
a plurality of in-coupling grating structures configured to couple the image lights into the optical combiner, wherein at least one of a grating period or a slant angle of a first in-coupling grating structure is different from at least one of a corresponding grating period or a corresponding slant angle of a second in-coupling grating structure; and
a plurality of out-coupling grating structures configured to couple the image lights out of the base structure along a longitudinal direction of the base structure,
wherein spatial distribution of the in-coupling grating structures along the longitudinal direction of the base structure overlaps with spatial distribution of the out-coupling grating structures along the longitudinal direction of the base structure.
14. The optical device of claim 13 , wherein:
for at least one of the in-coupling grating structures that couples an image light into the base structure, a set of two or more out-coupling grating structures are configured to couple the image light out of the base structure, and
the two or more out-coupling grating structures have at least one of a same grating period or a same slant angle.
15. The optical device of claim 13 , wherein the base structure comprises a photopolymer material, and the plurality of grating structures comprise a plurality of volume holographic grating structures recorded in the photopolymer material.
16. The optical device of claim 13 , wherein the plurality of grating structures comprise at least one of a volume holographic grating structure or a surface relief grating structure.
17. The optical device of claim 13 , wherein grating periods of at least two of the plurality of in-coupling grating structures are different, or slant angles of at least two of the plurality of in-coupling grating structures are different.
18. The optical device of claim 13 , wherein
the base structure comprises a first base structure and a second base structure,
the plurality of in-coupling grating structures are provided at the first base structure, and
the plurality of out-coupling grating structures are provided at the second base structure.
19. The optical device of claim 18 , further comprising:
a center substrate,
wherein the first base structure is disposed between the first substrate and the center substrate, and
wherein the second base structure is disposed between the center substrate and the second substrate.