Waveguide structure with segmented diffractive optical elements and near-eye display apparatus employing the same
Provided is a waveguide guiding light to a target area, the waveguide including an input-coupling diffractive optical element (DOE) inputting the light into the waveguide, an expanding DOE expanding the light input into the waveguide through the input-coupling DOE, an output-coupling DOE outputting the light expanded in the waveguide by the expanding DOE to an outside of the waveguide, wherein the expanding DOE includes a plurality of expanding segments, and the output-coupling DOE includes a plurality of output-coupling segments.
1. A waveguide guiding light to a target area, the waveguide comprising:
an input-coupling diffractive optical element (DOE) inputting the light into the waveguide;
an expanding DOE expanding the light input into the waveguide through the input-coupling DOE;
an output-coupling DOE outputting the light expanded in the waveguide by the expanding DOE to an outside of the waveguide,
wherein the expanding DOE comprises a plurality of expanding segments, and the output-coupling DOE comprises a plurality of output-coupling segments, and
wherein in all propagation directions of the light, as a distance from the input-coupling DOE increases, a density of each of the plurality of expanding segments decreases and a density of each of the plurality of output-coupling segments increases.
2. The waveguide of claim 1 , wherein an area comprising the plurality of expanding segments on the waveguide and an area comprising the plurality of output-coupling segments on the waveguide at least partially intersect.
3. The waveguide of claim 2 , wherein the plurality of expanding segments and the plurality of output-coupling segments do not intersect with each other.
4. The waveguide of claim 2 , wherein at least one of the plurality of expanding segments partially intersects with at least one of the plurality of output-coupling segments.
5. The waveguide of claim 2 , wherein at least one of the plurality of expanding segments is partially aligned with at least one of the plurality of output-coupling segments.
6. The waveguide of claim 1 , wherein a diffraction efficiency of the plurality of expanding segments is equal to a diffraction efficiency of the plurality of output-coupling segments.
7. The waveguide of claim 1 , wherein each of the plurality of expanding segments has a first diffraction efficiency, and each of the plurality of output-coupling segments has a second diffraction efficiency, and
wherein the first diffraction efficiency and the second diffraction efficiency are not equal to each other.
8. The waveguide of claim 1 , wherein diffraction efficiencies of at least one of the plurality of expanding segments or the plurality of output-coupling segments vary based on locations of the at least one of the plurality of expanding segments or the plurality of output-coupling segments on a surface of the waveguide.
9. The waveguide of claim 1 , wherein the plurality of expanding segments and/or the plurality of output-coupling segments have a circle shape, an arc shape, a sector shaper, a circle segment shape, or a polygon shape.
10. The waveguide of claim 1 , wherein adjacent segments of the plurality of expanding segments and adjacent segments of the plurality of output-coupling segments are spaced apart from each other on the waveguide.
11. The waveguide of claim 10 , wherein distances between the adjacent segments of the plurality of expanding segments and distances between the adjacent segments of the output-coupling segments are equal to each other.
12. The waveguide of claim 10 , wherein distances between the adjacent expanding segments of the expanding DOE are respectively a first distance, and distances between the adjacent output-coupling segments of the output-coupling DOE are respectively a second distance, and
wherein the first distance is not equal to the second distance.
13. The waveguide of claim 10 , wherein distances between the adjacent segments of at least one of the plurality of expanding segments or the plurality of output-coupling segments vary based on locations of the at least one of the plurality of expanding segments or the plurality of output-coupling segments on a surface of the waveguide.
14. The waveguide of claim 1 , wherein a size of each of the plurality of expanding segments is equal to a size of each of the plurality of output-coupling segments.
15. The waveguide of claim 1 , wherein a size of each of the plurality of expanding segments is a first size, and a size of each of the plurality of output-coupling segments is a second size, and
wherein the first size and the second size are not equal to each other.
16. The waveguide of claim 1 , wherein sizes of at least one of the plurality of expanding segments or the plurality of output-coupling segments vary based on locations of the at least one of the plurality of expanding segments or the plurality of output-coupling segments on a surface of the waveguide.
17. The waveguide of claim 1 , wherein a period and an effective thickness of each segment of the plurality of expanding segments and a period and an effective thickness of each of the plurality of output-coupling segments correspond to a location of the target area such that a diffraction efficiency of each segment is maximum with respect to the light output from the waveguide toward the target area.
18. The waveguide of claim 1 , wherein diffraction efficiencies of the plurality of expanding segments or the plurality of output coupling segments are different according to positions the plurality of expanding segments or the plurality of output coupling segments.
19. A near-eye display apparatus comprising:
a projector projecting light of an image; and
a waveguide comprising:
an input-coupling diffractive optical element (DOE) inputting the light into the waveguide;
an expanding DOE expanding the light input into the waveguide by the input-coupling DOE;
an output-coupling DOE outputting the light expanded by the expanding DOE in the waveguide to an outside of the waveguide,
wherein the expanding DOE comprises a plurality of expanding segments, and the output-coupling DOE comprises a plurality of output-coupling segments,
wherein in all propagation directions of the light, as a distance from the input-coupling DOE increases, a density of each of the plurality of expanding segments decreases and a density of each of the plurality of output-coupling segments increases, and
wherein the waveguide guides the light projected by the projector to a target area, the target area being a user's eye motion box.
20. A near-eye display apparatus comprising:
a left eye element comprising a first projector projecting light of an image and a first waveguide; and
a right eye element comprising a second projector projecting light of an image and a second waveguide,
wherein each of the first waveguide and the second waveguide comprises:
an input-coupling diffractive optical element (DOE) inputting the light into the waveguide;
an expanding DOE expanding the light input into the waveguide by the input-coupling DOE;
an output-coupling DOE outputting the light expanded by the expanding DOE in the waveguide to an outside of the waveguide,
wherein the expanding DOE comprises a plurality of expanding segments, and the output-coupling DOE comprises a plurality of output-coupling segments,
wherein in all propagation directions of the light, as a distance from the input-coupling DOE increases, a density of each of the plurality of expanding segments decreases and a density of each of the plurality of output-coupling segments increases, and
wherein the waveguide is provided in each of the left eye element and the right eye element such that plurality of output-coupling segments outputting the light projected by the projector are provided opposite to an area comprising a user's eye.