Eyepieces for augmented reality display system
An augmented reality display system can include a first eyepiece waveguide with a first input coupling grating (ICG) region. The first ICG region can receive a set of input beams of light corresponding to an input image having a corresponding field of view (FOV), and can in-couple a first subset of the input beams. The first subset of input beams can correspond to a first sub-portion of the FOV. The system can also include a second eyepiece waveguide with a second ICG region. The second ICG region can receive and in-couple at least a second subset of the input beams. The second subset of the input beams can correspond to a second sub-portion of the FOV. The first and second sub-portions of the FOV can be at least partially different but together include the complete FOV of the input image.
1. An augmented reality display system comprising:
a first eyepiece waveguide comprising a first optically transmissive substrate;
a first input coupling grating (ICG) region formed on or in the first eyepiece waveguide, the first ICG region being configured to receive a set of input beams of light, the set of input beams being associated with a set of k-vectors in k-space corresponding to an input image, and to translate the set of k-vectors to a location in k-space such that a first subset of the k-vectors lies inside a first k-space annulus associated with the first eyepiece waveguide, the first k-space annulus corresponding to a region in k-space associated with guided propagation in the first eyepiece waveguide;
a second eyepiece waveguide comprising a second optically transmissive substrate; and
a second input coupling grating (ICG) region formed on or in the second eyepiece waveguide, the second ICG region being configured to receive at least a portion of the set of input beams of light, and to translate the set of k-vectors to a location in k-space such that a second subset of the k-vectors lies inside a second k-space annulus associated with the second eyepiece waveguide, the second k-space annulus corresponding to a region in k-space associated with guided propagation in the second eyepiece waveguide;
wherein the first and second subsets of the k-vectors are at least partially different but together include a complete set of k-vectors corresponding to the input image.
2. The augmented reality display system of claim 1 , wherein the set of k-vectors corresponding to the input image has at least one dimension in k-space that is larger than a width of the first and second k-space annuli.
3. The augmented reality display system of claim 1 , wherein the display system satisfies the equation λ Blue /Λ 2 +k FoV /2<n, where n is a refractive index of the first and second eyepiece waveguides, λ Blue is a center wavelength of blue input light, Λ 2 is a period of the second ICG region, and k Fov is a k-space dimension of the input image in a direction of an ICG vector.
4. The augmented reality display system of claim 1 , wherein the display system satisfies the equation
n
-
λ
Green
Λ
1
>
1
-
λ
Green
Λ
2
,
where n is a refractive index of the first and second eyepiece waveguides, λ Green is a center wavelength of green input light, Λ 1 is a period of the first ICG region, and Λ 2 is a period of the second ICG region.
5. The augmented reality display system of claim 1 , wherein the display system satisfies the equation
n
-
λ
Red
Λ
1
>
1
-
λ
Red
Λ
2
where n is a refractive index of the first and second eyepiece waveguides, λ Red is a center wavelength of red input light, Λ 1 is a period of the first ICG region, and Λ 2 is a period of the second ICG region.
6. The augmented reality display system of claim 1 , wherein the display system satisfies the equation
Λ
1
<
λ
Blue
1
+
k
FoV
2
,
where n is a refractive index of the first and second eyepiece waveguides, λ Blue is a center wavelength of blue input light, Λ 1 is a period of the first ICG region, and k Fov is a k-space dimension of the input image in a direction of an ICG vector.
7. The augmented reality display system of claim 1 , wherein the display system satisfies the equation
2
λ
Blue
Λ
2
-
k
FoV
2
>
n
,
where n is a refractive index of the first and second eyepiece waveguides, λ Blue is a center wavelength of blue input light, Λ 2 is a period of the second ICG region, and k Fov is a k-space dimension of the input image in a direction of an ICG vector.
8. The augmented reality display system of claim 1 , wherein the display system satisfies the equation
Λ
2
>
λ
Green
n
-
k
FoV
2
,
where n is a refractive index of the first and second eyepiece waveguides, λ Green is a center wavelength of green input light, Λ 2 is a period of the second ICG region, and k Fov is a k-space dimension of the input image in a direction of an ICG vector.
9. The augmented reality display system of claim 1 , wherein:
the first ICG region has a first-order grating vector with a first magnitude,
the second ICG region has a first-order grating vector with a second magnitude, and
the first magnitude is larger than the second magnitude.
10. The augmented reality display system of claim 9 , further comprising a projector system configured to project the set of input beams toward the first and second eyepiece waveguides, wherein the first eyepiece waveguide is located before the second eyepiece waveguide along an optical path of the set of input beams.
11. The augmented reality display system of claim 1 , wherein the first and second subsets of the k-vectors partially overlap.
12. The augmented reality display system of claim 1 , wherein the first and second ICG regions are laterally aligned.
13. The augmented reality display system of claim 1 , wherein:
the first and second ICG regions are configured to receive input beams of light for a plurality of color components of the input image, the input beams for each color component being associated with a set of k-vectors in k-space,
the first ICG region is configured to translate the sets of k-vectors to locations in k-space such that first subsets of the k-vectors for two or more of the color components lie inside the first k-space annulus,
the second ICG region is configured to translate the sets of k-vectors to locations in k-space such that second subsets of the k-vectors for two or more of the color components lie inside the second k-space annulus, and
the first and second subsets of the k-vectors for the respective color components of the input image are at least partially different but together include the complete sets of k-vectors for the color components of the input image.
14. The augmented reality display system of claim 13 , wherein:
the first ICG region comprises a plurality of spatially separated sub-sections, each corresponding to one of the color components, and
the second ICG region comprises a plurality of spatially separated sub-sections, each corresponding to one of the color components.
15. The augmented reality display system of claim 13 , further comprising an optical filter positioned after the second eyepiece waveguide along an optical path of the input beams, the optical filter being configured to selectively absorb input beams for the color component having the shortest wavelength.
16. The augmented reality display system of claim 15 , wherein the optical filter is a yellow filter which absorbs at least 90% of blue light.
17. The augmented reality display system of claim 15 , wherein the optical filter is configured to selectively absorb input beams for the two color components having the two shortest wavelengths.
18. The augmented reality display system of claim 15 , wherein the optical filter is a red filter which absorbs at least 90% of green and blue light.
19. The augmented reality display system of claim 1 , wherein the first and second ICG regions have a first-order diffractive efficiency of 5-90%, and wherein the first ICG region is configured such that the second subset of k-vectors passes through without being diffracted.
20. The augmented reality display system of claim 1 , wherein the first and second eyepiece waveguides have a refractive index of 1.5-2.1.