Efficient hierarchical cropped exit pupil expander for compact diffraction waveguides

Abstract

Embodiments of the present disclosure relate to a device and method relating to an augmented reality waveguide combiner. The device includes a waveguide combiner, the waveguide combiner comprising: an input coupler operable to receive light and incouple light to the waveguide combiner; an output pupil expander (EPE) adjacent to the grid of the input coupler, the EPE having a stepped structure, the stepped structure having at least one band, the at least one band having a plurality of grid structures, and at least one of the plurality of grid structures having a fluctuating depth, fluctuating duty cycle, or fluctuating pitch different from the depth, duty cycle, or pitch of adjacent grid structures among the plurality of grid structures; and an output coupler operable to receive light from the EPE and transmit light over the user's field of view (FOV).

Description

Technical Field

[0001]

[0001] Embodiments of the present disclosure generally relate to augmented reality waveguide combiners. More specifically, the embodiments described herein relate to waveguide combiners having an efficient hierarchical output pupil expander.

[0002] Description of Related Art

[0002] Virtual reality is generally a computer-generated simulated environment in which a user has an apparent physical presence. A virtual reality experience is generated from a three-dimensional (3D) perspective and can be viewed through a head-mounted display (HMD) such as glasses or other wearable display devices having a near-eye display panel as a lens for displaying a virtual reality environment that substantially replaces the actual environment.

[0003]

[0003] Augmented reality (AR) enables a user to view the surrounding environment through the display lens of glasses or other HMD devices, but also to view images of virtual objects that are generated for display and appear as part of the environment. Augmented reality may include any type of input (e.g., voice input and haptic input), as well as virtual images, graphics, and videos that enhance or augment the environment experienced by the user. As a new technology, augmented reality has many challenges and design constraints.

[0004]

[0004] One such challenge is to display virtual images superimposed on the surrounding environment. Waveguide combiners are used to assist in the superimposition of images. The generated light is incoupled into the waveguide combiner, propagates through the extended waveguide combiner, and is outcoupled from this extended waveguide combiner and overlaid on the surrounding environment. The light is incoupled and outcoupled with the extended waveguide combiner using a surface relief diffraction grating.

[0005]

[0005] Therefore, what is needed in the art is a waveguide combiner having an efficient hierarchical exit pupil expander that effectively transmits incident light and expands the user field of view (FOV). [Overview of the project]

[0006]

[0006] In one embodiment, a device is disclosed. The device includes a waveguide combiner, which comprises an input coupler operable to receive light and incouple the light to the waveguide combiner, an output pupil expander (EPE) adjacent to the grid of the input coupler, having a stepped structure, the stepped structure comprising at least one band, the at least one band comprising a plurality of grid structures, and at least one of the plurality of grid structures having a varying depth, a varying duty cycle, or a varying pitch that differs from the depth, duty cycle, or pitch of adjacent grid structures among the plurality of grid structures, and an output coupler operable to receive light from the EPE and transmit the light over the user's field of view (FOV).

[0007]

[0007] In another embodiment, a device is disclosed. The device comprises a substrate, an optical engine disposed above the substrate, and a waveguide combiner disposed on the substrate, the EPE having an input coupler operable to receive light and incouple the light to the waveguide combiner, an output pupil expander (EPE) adjacent to the grid of the input coupler having a stepped structure, the stepped structure comprising at least one band, the at least one band comprising a plurality of grid structures, and at least one of the plurality of grid structures having a varying depth, a varying duty cycle, or a varying pitch that is different from the depth, duty cycle, or pitch of adjacent grid structures among the plurality of grid structures, and a waveguide combiner having an output coupler operable to receive light from the EPE and transmit the light onto a user field of view (FOV), wherein the user FOV is disposed adjacent to the waveguide combiner, and the user FOV is operable to receive light from the waveguide combiner and display the light.

[0008]

[0008] In another embodiment, a method is disclosed. The method involves incoupling light to a waveguide combiner, wherein the waveguide combiner includes an input coupler operable to receive light, an exit pupil expander (EPE) adjacent to the grating of the input coupler having a stepped structure, the stepped structure comprising at least one band, the at least one band comprising a plurality of grating structures, and at least one of the plurality of grating structures having a fluctuating depth, fluctuating duty cycle, or fluctuating pitch different from the depth, duty cycle, or pitch of the grating structures of the plurality of grating structures, and an output coupler. The method includes incoupling light to a waveguide combiner, reflecting the light in the EPE, interacting the light in the plurality of grating structures within the EPE, and outcoupling light at the output coupler, wherein the output coupler is operable to receive light from the EPE and transmit the light onto the user's field of view (FOV).

[0009]

[0009] To enable a more detailed understanding of the above-mentioned features of the Disclosure, a more detailed description of the Disclosure, which has been briefly summarized above, can be given by reference to embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings show only exemplary embodiments and should not be considered to limit the scope of the Disclosure, as other equally valid embodiments are also permissible. [Brief explanation of the drawing]

[0010] [Figure 1A] This is a schematic top view of a waveguide combiner having an exit pupil expander (EPE) according to a certain embodiment. [Figure 1B] This is an example of a schematic diagram of the output of a waveguide combiner according to a certain embodiment. [Figure 2A]This is a schematic top view of a first waveguide combiner having an efficiency-hierarchical EPE according to a particular embodiment of this specification. [Figure 2B] This is a schematic top view of a second waveguide combiner having an efficiency-hierarchical EPE according to a particular embodiment of this specification. [Figure 3A-3J] 3A, 3C, 3E, 3G, and 3I are examples of schematic top views of a second waveguide combiner with various efficiency hierarchical EPEs. 3B, 3D, 3F, 3H, and 3J are examples of cross-sectional side views of multiple grid structures according to specific embodiments. [Figure 3K] Figure 3L is an example of a schematic top view of a first waveguide combiner according to a specific embodiment, and Figure 3L is an example of a cross-sectional side view of a plurality of grid structures. [Figure 4A-4C] This is an example of a schematic top view of multiple grid structures according to the embodiment. [Modes for carrying out the invention]

[0011]

[0017] To facilitate understanding, the same reference numerals were used where possible to indicate identical elements common to multiple figures. It is assumed that elements and features of one embodiment may be usefully incorporated into other embodiments without further description.

[0012]

[0018] Embodiments of this disclosure generally relate to augmented reality waveguide combiners. More specifically, embodiments described herein relate to waveguide combiners having an efficiency-staggered exit pupil expander (EPE). The efficiency-staggered EPE is a grid placed on the substrate of the waveguide combiner. As described herein, the efficiency-staggered EPE facilitates multiple interactions with light as light moves laterally within the EPE. The efficiently stacked EPE directs light away from a truncated region of the exit pupil expander. The truncated region may include the edge of the waveguide combiner or the edge of the substrate on which the waveguide combiner is placed. The efficiency-staggered EPE directs light toward the output coupler. The controlled direction of light within the efficiency-staggered EPE enables a large user field of view (FOV).

[0013]

[0019] Figure 1A is a schematic top view of the waveguide combiner 100 in operation. The waveguide combiner 100 includes a substrate 102. The input coupler 104, EPE 106, and output coupler 108 are located in, on, or above the substrate 102. The input coupler 104 is aligned with the optical engine 110. The operating optical engine 110 projects an incident beam (e.g., a virtual image) onto the input coupler 104. The incident beam is shown as the input beam 112. The input coupler 104 receives the input beam 112. The input beam 112 is incoupled within the input coupler 104 so that the input beam 112 undergoes total internal reflection (TIR) ​​through the substrate 102 until it contacts the lattice structure of the EPE 106. The T1 beam 114 undergoes TIR within the EPE 106 until the T1 beam 114 contacts another lattice structure. Next, the T-1 beam is coupled to the output coupler 108. The T1 beam, which undergoes TIR within EPE 106, continues to contact the lattice structure until the intensity of the T1 beam 114 is depleted or the remaining T1 beam 114 propagating through EPE 106 reaches the edge of EPE 106.

[0014]

[0020] Figure 1B is a schematic diagram of the user field of view (FOV) 118. The grid structure of the EPE must be adjusted to control the T1 beam coupled to the EPE 106 in order to control the intensity of the T-1 beam coupled to the output coupler 108, modulating the user FOV 118 generated from the microdisplay from the user's viewpoint, and increasing the field of view in which the user can see the virtual image. A larger user FOV results in a larger field of view. It is desirable to increase the user FOV without increasing the surface area of ​​the substrate 102.

[0015]

[0021] Figure 2A is a schematic top view of the first waveguide combiner 202. The first waveguide combiner 202 includes an efficiency-staggered EPE 206. Figure 2B is a schematic top view of the second waveguide combiner 204 having the efficiency-staggered EPE 206. The efficiency-staggered EPE 206 has a first boundary 124, a second boundary 126, and a third boundary 130. The first boundary 124 and the second boundary 126 are angled from the input coupler 104 and extend from the input coupler 104. The third boundary 130 of the EPE 106 is along at least one edge of the substrate 102, such as edge 116 (for example, a grid structure 300 when the efficiency-staggered EPE 206 extends to at least one edge of the substrate 102, such as edge 116). At least a portion of the second boundary 126 and the third boundary 130 of the efficiency hierarchical EPE 206 of the second waveguide combiner 204 is conformal with respect to the edge 116 of the substrate 102.

[0016]

[0022] In some embodiments, efficiency-hierarchical EPE206 can be defined by a lattice vector. The lattice vector is a function of the lattice across the efficiency-hierarchical EPE206 material, which is a periodic optical structure that diffracts light in a wavelength-dependent direction. grating ) describes the periodicity and direction of the lattice. Λ x and Λ yThese can define periodicity in x and y, respectively. In a k-space (wavenumber) plot, the grid vectors are often normalized by k0, which is the wave vector of light in free space. This normalized grid vector is now wavelength-dependent. The minimum grid area (MGR) for the efficiency-hierarchical EPE206 may be useful for supporting the entire waveguide combiner user FOV across the output. This is provided by the grid vectors of each color and the k-space diagram and maximum angular range (MAE) of the FOV. The steepest lines of the MAE intersecting the first boundary 124, second boundary 126, and third boundary 130 of the grid of the input coupler 104 and output coupler 108 define the MGR of the grid for the efficiency-hierarchical EPE206. In some cases, larger FOVs require larger efficiency-hierarchical EPE206 grid areas.

[0017]

[0023] The first waveguide combiner 202 and the second waveguide combiner 204 include a substrate 102, an input coupler 104, an efficiency-staggered EPE 206, and an output coupler 108. The substrate 102 of the first waveguide combiner 202 and the second waveguide combiner 204 includes an input coupler 104, an efficiency-staggered EPE 206, and an output coupler 108. The input coupler 104 can inject light from the optical engine 110 into the waveguide combiner (e.g., the first waveguide combiner 202 and the second waveguide combiner 204) and transmit the light to the efficiently laddered EPE 206. The efficiency-staggered EPE 206 includes a plurality of lattice structures 300. In other embodiments, the optical engine 110 generates light having one or more wavelengths and transmits the light to the input coupler 104. For example, the optical engine 110 generates light having a single wavelength or wavelength range corresponding to a single color or group of colors. In another embodiment, single-color wavelength light is generated by the optical engine 110 and transmitted to the input coupler 104. The light is reflected from the efficiency-tiered EPE 206 toward the output coupler 108, where it is outcoupled to a display (e.g., user FOV). The size of the efficiency-tiered EPE 206 is related to the shape of the input coupler 104 and the waveguide combiners (e.g., a first waveguide combiner and a second waveguide combiner). For example, as shown in Figure 2A, the first waveguide combiner 202 includes a substrate 102 having a rectangular shape. As a further example, as shown in Figure 2B, the second waveguide combiner 204 includes a substrate 102 having rounded edge portions 120. The efficiency tiering EPE206 is positioned on the rounded edge portion 120 of the second waveguide combiner 204.

[0018]

[0024] The efficiency-staggered EPE206 includes increasing the 6-lattice efficiency across the efficiency-staggered EPE206 to facilitate light (e.g., light 218a, light 218b, or light 218c) moving laterally within the efficiency-staggered EPE206 and away from the edge 116 of the substrate 102. For example, the efficiency-staggered EPE206 includes multiple bands (e.g., a first band 232 and a second band 234). Each band (e.g., a first band 232 and a second band 234) includes multiple lattice structures 300, including varying depths, varying duty cycles, and / or varying pitches, which form a high-efficiency lattice (see Figures 3A to 3J). Alternatively or additionally, the efficiency-staggered EPE206 may include one efficiency-staggered band (e.g., a first band 232). The first band 232 in the efficiently loaded EPE206 redirects light 218a away from the edge 116. For example, if light 218a is directed toward edge 116, a missing interaction 240 may occur. The missing interaction 240 allows for a reduction in FOV. From the first band 232, light 218b moves to at least the second band 234. From the second band 234, light 218c moves toward the output coupler 108. Multiple optical interaction points 238 across the efficiency-hierarchical EPE 206 are represented by dotted circles in Figures 2A and 2B. The optical interaction points 238 represent locations where light (e.g., light 218a, light 218b, or light 218c) can come into contact with multiple lattice structures 300. The increase in lattice efficiency across the efficiency-hierarchical EPE 206 increases the output FOV. Specifically, because EPE 106 is truncated, light from the original optical path does not appear in the FOV of the waveguide combiner 100. EPE106 may be trimmed by the edge 116 of the substrate 102. Light transmitted across the waveguide combiner (e.g., first waveguide combiner 202 or second waveguide combiner 204) (e.g., light 218a, light 218b, and light 218c) appears in the user FOV 118, as shown in Figure 1B.

[0019]

[0025] Figures 3A, 3C, 3E, 3G, and 3I are examples of schematic top views of a second waveguide combiner 204 having various efficiency-hierarchical EPEs. Figures 3B, 3D, 3F, 3H, and 3J are examples of cross-sectional side views of multiple grid structures 300. Figure 3K is an example of a schematic top view of a first waveguide combiner 202. Figure 3L is an example of a cross-sectional side view of multiple grid structures 300. The first waveguide combiner 202 and the second waveguide combiner 204 include a substrate 102, an input coupler 104, efficiency-hierarchical EPEs 206, and an output coupler 108. The input coupler 104, efficiency-hierarchical EPEs 206, and output coupler 108 are located in, on, or above the substrate 102. The efficiency-hierarchical EPEs 206 include multiple grid structures 300. Multiple grid structures 300 form bands (e.g., a first band 232 or a second band 234) on the efficiency-hierarchical EPE 206. In some embodiments, the multiple grid structures 300 and the bands (e.g., a first band 232 or a second band 234) are formed in a diagonal pattern. The bands (e.g., the first band 232 and the second band 234) are formed by variations in the grid structures 300. For example, as shown in Figures 3A to 3J, the bands (e.g., the first band 232 and the second band 234) are shown on the efficiency-hierarchical EPE 206, but it should be understood that in other embodiments, additional bands may be formed on the efficiency-hierarchical EPE 206. The additional bands may be formed by variations in the grid structures 300 within the additional bands. Multiple grid structures 300 can be one-dimensional or two-dimensional grid shapes. As an example, a top view of a one-dimensional grid shape is shown as shown in Figure 4A. As shown in Figure 4B, a top view of a two-dimensional grid shape is shown as an example. As shown in Figure 4C, a top view of an additional two-dimensional grid is shown as an example. Examples of varying the multiple grid structures 300 may include binary grids, inclined grids, blazed grids, or generalized grids (e.g., grids with organic shapes). The multiple grid structures 300 direct the light toward the output coupler 108 so that it moves away from the edge 116 of the substrate 102, as described above. The efficiency range of the multiple grid structures 300 may be in the range of about 0% to about 15%, but other values ​​are also possible.Variable lattice efficiency can be achieved through variable pitch, duty cycle, and / or depth of the plurality of lattice structures 300.

[0020]

[0026] As shown in FIGS. 3A and 3B, the plurality of lattice structures 300 disposed on the second waveguide combiner 204 include depth variations 302. FIG. 3B shows a cross-section along line A’-A’’ shown in FIG. 3A. The depth 302a of the plurality of lattice structures 300 is about 300 nm or less. The variation in depth 302a across the efficiency stratification EPE 206 affects the shape of the first band 232 and the second band 234.

[0021]

[0027] As shown in FIGS. 3C and 3D, the plurality of lattice structures disposed on the second waveguide combiner 204 include duty cycle variations 304. FIG. 3D shows a cross-section along line B’-B’’ shown in FIG. 3C. The duty cycle is determined by dividing the boundary dimension 304a (e.g., width) of the lattice structure of the plurality of lattice structures 300 by the pitch 304b (e.g., distance between the first edges) of the lattice structure. The duty cycle variation 304 is from about 0.1 to about 0.9. The duty cycle variation 304 across the efficiency stratification EPE 206 affects the shape of the first band 232 and the second band 234.

[0022]

[0028] As shown in FIGS. 3E and 3F, the plurality of lattice structures 300 disposed on the second waveguide combiner 204 include pitch variations 306. FIG. 3F shows a cross-section along line C’-C’’ shown in FIG. 3E. The pitch variation 306 is defined by the distance between the first edges 306a of the plurality of lattice structures 300. The pitch variation 306 is from about -10 to about 10Λ. The pitch variation 306 across the efficiency stratification EPE 206 affects the shape of the first band 232 and the second band 234.

[0023]

[0029] As shown in Figures 3G and 3H, the multiple grid structures 300 arranged on the second waveguide combiner 204 include a second variable depth 308. Figure 3H shows a cross-section along the line D'~D'' shown in Figure 3G. The second variable depth 308 forms a first band 232 on the efficiency hierarchical EPE 206 (for example, one band is formed on the efficiency hierarchical EPE 206). The first band 232 is formed where the depth 308a is greater compared to other areas on the grid, for example, 308b.

[0024]

[0030] As shown in Figures 3I and 3J, the multiple grid structures 300 arranged on the second waveguide combiner 204 include a second pitch variation 310. Figure 3J shows a cross-section along the line E'~E'' shown in Figure 3I. The second pitch variation 310 includes a change in pitch 310a that forms a first band 232 (for example, one band is formed on the efficiency hierarchical EPE 206). The first band 232 forms pitch 310b where pitch 310a changes compared to other regions within the multiple grid structures 300.

[0025]

[0031] As shown in Figures 3K and 3L, the multiple grid structures arranged on the first waveguide combiner 202 include duty cycle variations 304. Figure 3L shows a cross-section along the line F'~F'' shown in Figure 3K. The duty cycle is determined by dividing the boundary dimension 304a (e.g., width) of the grid structures 300 by the pitch 304b (e.g., distance between the first edges) of the grid structures. The duty cycle variation 304 is approximately 0.1 to approximately 0.9. The duty cycle variation 304 across the efficiency hierarchical EPE 206 affects the shapes of the first band 232 and the second band 234.

[0026]

[0032] This disclosure provides a device having an efficiency-staggered EPE. The efficiency-staggered EPE facilitates multiple interactions with light as light moves laterally within the EPE. These interactions direct the light away from a truncated region of the waveguide or EPE and towards the output coupler. The truncated region may include the edge of the waveguide combiner or the edge of the substrate on which the waveguide combiner is placed. The controlled direction of light within the efficiency-staggered EPE allows for a large user field of view (FOV), flexibility in the waveguide combiner layout design, and a lighter waveguide combiner, enabling easy all-day wear by the user.

[0027]

[0033] The above description applies to embodiments of the present disclosure, but other embodiments and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, and the scope of the present disclosure is determined by the following claims.

Claims

1. A device comprising a waveguide combiner, wherein the waveguide combiner is An input coupler capable of receiving light and incoupling the light to the waveguide combiner, An exit pupil expander (EPE) adjacent to the grid of the input coupler, having a stepped structure, wherein the stepped structure includes at least one band, the at least one band includes a plurality of grid structures, and at least one of the plurality of grid structures has a fluctuating depth, fluctuating duty cycle, or fluctuating pitch that is different from the depth, duty cycle, or pitch of adjacent grid structures among the plurality of grid structures, An output coupler capable of receiving light from the EPE and transmitting the light onto the user's field of view (FOV), A device that includes this.

2. Optical engine located above the waveguide combiner, including a pupil located above the input coupler. The device according to claim 1, further comprising:

3. The device according to claim 1, wherein the plurality of grid structures have the variable depth.

4. The device according to claim 1, wherein the plurality of grid structures have the variable duty cycle.

5. The device according to claim 1, wherein the plurality of grid structures have the variable pitch.

6. The device according to claim 1, wherein the plurality of lattice structures include a one-dimensional structure.

7. The device according to claim 1, wherein the plurality of lattice structures include a two-dimensional structure.

8. The device according to claim 1, wherein the stepped structure is arranged in a diagonal pattern across the EPE.

9. The device according to claim 1, wherein the EPE includes a first boundary, a second boundary, and a third boundary, and at least one of the first boundary, the second boundary, or the third boundary is conformal to the edge of the substrate.

10. The device according to claim 1, wherein the waveguide combiner includes a rounded edge portion.

11. The device according to claim 10, wherein a portion of the EPE is conformal to the rounded edge portion.

12. The device according to claim 1, wherein the stepped structure has a grid efficiency value.

13. It is a device, circuit board and An optical engine positioned above the aforementioned substrate, A waveguide combiner disposed on the substrate, An input coupler capable of receiving light and incoupling the light to the waveguide combiner, An exit pupil expander (EPE) adjacent to the grid of the input coupler, having a stepped structure, wherein the stepped structure includes at least one band, the at least one band includes a plurality of grid structures, and at least one of the plurality of grid structures has a fluctuating depth, a fluctuating duty cycle, or a fluctuating pitch that is different from the depth, duty cycle, or pitch of adjacent grid structures among the plurality of grid structures. , and An output coupler capable of receiving light from the EPE and transmitting the light onto the user's field of view (FOV). Waveguide combiner including Equipped with, The user FOV is positioned adjacent to the waveguide combiner and is a device capable of receiving the light from the waveguide combiner and displaying the light.

14. The device according to claim 13, wherein the EPE includes at least two bands.

15. The device according to claim 10, wherein the stepped structure is arranged in an oblique orientation across the EPE.

16. The device according to claim 13, wherein the stepped structure has a grid efficiency value, and the grid efficiency value is at least partially based on at least one of the pitch, the duty cycle, and the depth of the stepped structure.

17. The method involves incoupling light to a waveguide combiner, wherein the waveguide combiner is An input coupler capable of receiving the aforementioned light, An exit pupil expander (EPE) adjacent to the grid of the input coupler, having a stepped structure, wherein the stepped structure includes at least one band, the at least one band includes a plurality of grid structures, and at least one of the plurality of grid structures has a fluctuating depth, fluctuating duty cycle, or fluctuating pitch that is different from the depth, duty cycle, or pitch of adjacent grid structures among the plurality of grid structures, and Output coupler This includes incoupling light in a waveguide combiner, The EPE reflects the light, The light within the EPE interacts with the plurality of lattice structures, A method comprising outcoupling the light in the output coupler such that the output coupler is operable to receive the light from the EPE and transmit the light onto the user's field of view (FOV).

18. The light within the EPE is made to interact at multiple photo-interaction points, To direct the light away from the edges of the waveguide combiner of the EPE having the plurality of lattice structures. The method according to claim 17, further comprising:

19. The method according to claim 17, wherein multiple light beams are directed into the waveguide combiner.

20. The method according to claim 17, wherein the stepped structure has a grid efficiency value, and the grid efficiency value is at least partially based on at least one of the pitch, duty cycle, and depth of the plurality of grid structures.

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