Efficiency specified cut-output

Abstract

Embodiments of the present disclosure relate to apparatuses and methods related to augmented reality waveguide combiners. In one embodiment, an apparatus comprises a waveguide combiner comprising an input coupler operable to receive light and to input-couple the light into the waveguide combiner; an exit pupil expander (ERE) adjacent to the grating of the input coupler, the ERE having a hierarchical structure comprising at least one band comprising a plurality of grating structures, at least one of the plurality of grating structures has a varying depth, a varying duty cycle, or a varying pitch different from the depth, duty cycle, or pitch of an adjacent grating structure of the plurality of grating structures; and an output coupler operable to receive light from the ERE and to transmit the light onto a user field of view (FOV).

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to augmented reality waveguide combiners. More specifically, the embodiments described herein relate to waveguide combiners with efficiency-laddered exit pupil expanders. BACKGROUND

[0002] Virtual reality is generally a computer-generated simulated environment in which a user has a strong sense of presence. Virtual reality experiences can be generated from a three-dimensional (3D) perspective and viewed with a head-mounted display (HMD), such as glasses or other wearable display devices that have near-eye display panels as lenses to display virtual reality environments that substantially replace the actual environment.

[0003] Augmented reality (AR) enables an experience in which a user can still view the surrounding environment via the display lenses of glasses or other HMD devices, but also see images of virtual objects that are generated to be displayed and appear as part of the environment. Augmented reality can include any type of input, such as audio and haptic input, as well as virtual images, graphics, and video that augment or enhance the environment experienced by the user. As an emerging technology, augmented reality presents many challenges and design constraints.

[0004] One such challenge is displaying virtual images that are superimposed on the surrounding environment. Waveguide combiners are used to assist in superimposing the images. Generated light is input-coupled into the waveguide combiner, propagates through the augmented waveguide combiner, output-coupled from the augmented waveguide combiner, and superimposed on the surrounding environment. Surface-relief gratings are used to couple light into and out of the augmented waveguide combiner.

[0005] Accordingly, there is a need in the art for waveguide combiners with efficiency-laddered exit pupil expanders that efficiently transmit input light to expand the field of view (FOV) of a user. SUMMARY

[0006] In one embodiment, an apparatus is disclosed. The apparatus includes a waveguide combiner comprising: an input-coupler operable to receive light and input-couple the light into the waveguide combiner; a grating-adjacent exit pupil expander (EPE) of the input-coupler, the EPE having a laddered structure comprising at least one band comprising a plurality of grating structures, at least one of the plurality of grating structures having a varying depth, a varying duty cycle, or a varying pitch that is different from a depth, a duty cycle, or a pitch of an adjacent one of the plurality of grating structures; and an output-coupler operable to receive light from the EPE and transmit the light onto a field of view (FOV) of a user.

[0007] In another implementation, an apparatus is disclosed. The apparatus comprises a substrate, a light engine disposed above the substrate, a waveguide combiner disposed on the substrate, the waveguide combiner comprising: an input coupler operable to receive light and input couple the light into the waveguide combiner; an exit pupil expander (EPE) adjacent to a grating of the input coupler, the EPE having a hierarchical structure comprising at least one band, the at least one band comprising a plurality of grating structures, at least one grating structure of the plurality of grating structures having a varying depth, a varying duty cycle, or a varying pitch that is different from a depth, a duty cycle, or a pitch of an adjacent grating structure of the plurality of grating structures; and an output coupler operable to receive light from the EPE and transmit the light onto a user field of view (FOV), and the user FOV is disposed adjacent to the waveguide combiner, the user FOV operable to receive light from the waveguide combiner and display the light.

[0008] In another implementation, a method is disclosed. The method comprises input coupling light into a waveguide combiner, the waveguide combiner comprising: an input coupler operable to receive light; an exit pupil expander (EPE) adjacent to a grating of the input coupler, the EPE having a hierarchical structure comprising at least one band, the at least one band comprising a plurality of grating structures, at least one grating structure of the plurality of grating structures having a varying depth, a varying duty cycle, or a varying pitch that is different from a depth, a duty cycle, or a pitch of an adjacent grating structure of the plurality of grating structures; and an output coupler, reflecting light at the EPE, causing light within the EPE to interact with the plurality of grating structures, and output coupling light at the output coupler, the output coupler operable to receive light from the EPE and transmit the light onto a user field of view (FOV). BRIEF DESCRIPTION OF DRAWINGS

[0009] So that the manner in which the above-recited features and advantages of the present disclosure can be understood in detail, a more particular description, briefly summarized above, can be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only example embodiments and are therefore not to be considered limiting of its scope, as the scope can allow for other equally effective embodiments.

[0010] FIG. 1A The additional figures are schematic top views of waveguide combiners with exit pupil expanders (EPEs) of certain embodiments.

[0011] FIG. 1B Is an example schematic of an output of a waveguide combiner according to certain embodiments.

[0012] FIG. 2A is a schematic top view of a first waveguide combiner with efficiency- phased EPE according to certain embodiments herein.

[0013] FIG. 2B is a schematic top view of a second waveguide combiner with efficiency- phased EPE according to certain embodiments herein.

[0014] FIG. 3A FIG. 3C FIG. 3E FIG. 3G FIG. 3I are examples of schematic top views of a second waveguide combiner with various efficiency-phased EPE. FIG. 3B FIG. 3D FIG. 3F FIG. 3H FIG. 3J are examples of cross-sectional side views of a plurality of grating structures according to certain embodiments.

[0015] According to certain embodiments, FIG. 3K is an example of a schematic top view of a first waveguide combiner, and FIG. 3L is an example of a cross-sectional side view of a plurality of grating structures.

[0016] FIG. 4A to FIG. 4C is an example of a schematic top view of a plurality of grating structures according to embodiments.

[0017] To facilitate an understanding of this description, like reference characters are used to identify like elements in each of the figures. It is intended that elements and features of one implementation can be beneficially incorporated into other implementations, without further recitation. DETAILED DESCRIPTION

[0018] Embodiments of the present disclosure generally relate to augmented reality waveguide combiners. More specifically, embodiments described herein relate to waveguide combiners with efficiency-phased exit pupil expanders (EPEs). The efficiency-phased EPE is a grating disposed on a substrate of the waveguide combiner. As described herein, the efficiency-phased EPE facilitates multiple interactions with light as the light moves laterally within the EPE. The efficiency-phased EPE directs light away from a cutout region of the exit pupil expander. The cutout region can include an edge of the waveguide combiner or an edge of a substrate on which the waveguide combiner is disposed. The efficiency-phased EPE directs light toward an output coupler. The controlled direction of light within the efficiency-phased EPE allows for a large field of view (FOV) for a user.

[0019] FIG. 1A ​​​​​​​​is a schematic top view of a waveguide combiner 100 in operation. The waveguide combiner 100 includes a substrate 102. An input coupler 104, an EPE 106, and an output coupler 108 are disposed in, on, or above the substrate 102. The input coupler 104 is aligned with a light engine 110. In operation, the light engine 110 projects an incident light beam (e.g., a virtual image) to the input coupler 104. The incident light beam is shown as input light beam 112. The input coupler 104 receives the input light beam 112. The input light beam 112 is in-coupled by the input coupler 104 such that the input light beam 112 experiences total internal reflection (TIR) through the substrate 102 until the input light beam 112 begins to contact the grating structure of the EPE 106. The T1 light beam 114 experiences TIR in the EPE 106 until the T1 light beam 114 contacts another grating structure. The T-1 light beam is then coupled to the output coupler 108. The T1 light beam that experiences TIR in the EPE 106 continues to contact the grating structure until the intensity of the T1 light beam 114 is exhausted or the remaining T1 light beam 114 that propagates through the EPE 106 reaches an end of the EPE 106.

[0020] FIG. 1B is a schematic illustration of a user field of view (FOV) 118. The grating structure of the EPE must be tuned to control the T1 light beams coupled in the EPE 106 in order to control the intensity of the T-1 light beams coupled to the output coupler 108 to adjust the user FOV 118 produced from the microdisplay from the user's perspective and to increase the viewing angle at which the user can view the virtual image. A larger user FOV results in an increased viewing angle. It is desirable to increase the user FOV without increasing the surface area of the substrate 102.

[0021] FIG. 2A is a schematic top view of a first waveguide combiner 202. The first waveguide combiner 202 includes an efficiency staged EPE 206. FIG. 2B is a schematic top view of a second waveguide combiner 204 with an efficiency staged EPE 206. The efficiency staged 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, where the first boundary 124 and the second boundary 126 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 (e.g., grating structure 300 if the efficiency staged EPE 206 extends to at least one edge, such as edge 116 of the substrate 102). At least a portion of the second boundary 126 and the third boundary 130 of the efficiency staged EPE 206 of the second waveguide combiner 204 is conformal with the edge 116 of the substrate 102.

[0022] In some implementations, the efficiency phased EPE 206 can be defined by grating vectors. Grating vectors are a function of the periodic optical structure across the grating of the efficiency phased EPE 206 material that diffracts light into a wavelength dependent direction. The grating vector (k grating ) describes the periodicity and direction of the grating. and The periodicity in x and y can be defined respectively. In k-space (wave number) diagrams, the grating vector is often normalized by k0, the wave vector of light in free space. This normalized grating vector is now wavelength dependent. The minimum grating region (MGR) for the efficiency phased EPE 206 can be used to indicate the entire waveguide combiner user FOV across the output. This is provided by the k-space diagram and the maximum angular extent (MAE) of the grating vector and FOV for each color. The MAE intersecting the first, second, and third boundaries 124, 126, 130 of the grating of the input coupler 104 and the output coupler 108 define the MGR of the grating of the efficiency phased EPE 206. In some cases, a larger FOV requires a larger efficiency phased EPE 206 grating region.

[0023] The first waveguide combiner 202 and the second waveguide combiner 204 include a substrate 102, an input coupler 104, an efficiency phased EPE 206, and an output coupler 108. The substrate 102 of the first waveguide combiner 202 and the second waveguide combiner 204 contains the input coupler 104, the efficiency phased EPE 206, and the output coupler 108. The input coupler 104 is capable of input coupling light from the light engine 110 into the waveguide combiner (e.g., the first waveguide combiner 202 and the second waveguide combiner 204) and transmitting the light to the efficiency phased EPE 206. The efficiency phased EPE 206 includes a plurality of grating structures 300. In other implementations, the light engine 110 generates light having one or more wavelengths and transmits the light to the input coupler 104. For example, the light engine 110 generates light having a single wavelength or a range of wavelengths corresponding to a single color or a group of colors. In other implementations, a single color wavelength light is generated by the light engine 110 and transmitted to the input coupler 104. The light reflects from the efficiency phased EPE 206 toward the output coupler 108, where the light is output coupled to a display (e.g., a user FOV). The size of the efficiency phased EPE 206 is related to the input coupler 104 and the shape of the waveguide combiner (e.g., the first waveguide combiner and the second waveguide combiner). For example, as shown in FIG. 2A, the first waveguide combiner 202 includes a substrate 102 having a rectangular shape. As another example, as shown in FIG. 2B, the first waveguide combiner 202 includes a substrate 102 having a circular shape. FIG. 2A FIG. 2B ​As shown, the second waveguide combiner 204 includes the substrate 102 with the rounded edge portion 120. The efficiency phasing EPE 206 is disposed over the rounded edge portion 120 of the second waveguide combiner 204.

[0024] The efficiency phasing EPE 206 includes a diagonal increase in grating efficiency across the efficiency phasing EPE 206 to facilitate lateral movement of light (e.g., light 218a, light 218b, or light 218c) within the efficiency phasing EPE 206 and away from the edge 116 of the substrate 102. For example, the efficiency phasing EPE 206 includes a plurality of bands (e.g., a first band 232 and a second band 234). Each band (e.g., the first band 232 and the second band 234) includes a plurality of grating structures 300 forming a high efficiency grating that includes varying depths, varying duty cycles, and / or varying pitches (see FIG. 3A to FIG. 3J ). Alternatively or additionally, the efficiency phasing EPE 206 can include one efficiency phasing band (e.g., the first band 232). The first band 232 within the efficiency phasing EPE 206 redirects the light 218a away from the edge 116. For example, there can be a missing interaction 240 when the light 218a is directed toward the edge 116. The missing interaction 240 allows for a reduced FOV. The light 218b moves from the first band 232 to at least the second band 234. The light 218c moves from the second band 234 toward the output coupler 108. A plurality of light interaction points 238 across the efficiency phasing EPE 206 are represented in dashed circles in FIG. 2A and FIG. 2B . The light interaction points 238 represent locations where light (e.g., light 218a, light 218b, or light 218c) can contact a plurality of grating structures 300. The increased grating efficiency across the efficiency phasing EPE 206 increases the output FOV. In particular, because the EPE 106 is cropped, light from the original light path does not appear in the FOV of the waveguide combiner 100. The EPE 106 can be cropped by the edge 116 of the substrate 102. Light (e.g., light 218a, light 218b, and light 218c) transmitted across the waveguide combiner (e.g., the first waveguide combiner 202 or the second waveguide combiner 204) appears in the user FOV 118 as FIG. 1B shown.

[0025] FIG. 3A , FIG. 3C , FIG. 3E , FIG. 3G and FIG. 3I are examples of schematic top views of the second waveguide combiner 204 with various efficiency phasing EPEs 206. FIG. 3B , FIG. 3D , FIG. 3F , FIG. 3H and FIG. 3Jis an example of a cross-sectional side view of a plurality of grating structures 300. FIG. 3K is an example of a schematic top view of a first waveguide combiner 202. FIG. 3L is an example of a cross-sectional side view of a plurality of grating structures 300. The first waveguide combiner 202 and the second waveguide combiner 204 include a substrate 102, an input coupler 104, an efficiency phased EPE 206, and an output coupler 108. The input coupler 104, the efficiency phased EPE 206, and the output coupler 108 are disposed in the substrate 102, on the substrate 102, or above the substrate 102. The efficiency phased EPE 206 includes a plurality of grating structures 300. The plurality of grating structures 300 form a band (e.g., a first band 232 or a second band 234) on the efficiency phased EPE 206. In some implementations, the plurality of grating structures 300 and the band (e.g., the first band 232 or the second band 234) are formed in a diagonal pattern. The band (e.g., the first band 232 and the second band 234) is formed by a variation in the grating structures 300. For example, as shown in FIG. 3A to FIG. 3J , the band (e.g., the first band 232 and the second band 234) is shown as being located on the efficiency phased EPE 206, however, it should be understood that in other implementations, additional bands can be formed on the efficiency phased EPE 206. The additional bands can be formed by a variation in the grating structures 300 within the additional bands. The plurality of grating structures 300 can be a 1-D or 2-D grating shape. As shown in FIG. 4A , a top view of a 1-D grating shape is shown as an example. As shown in FIG. 4B , a top view of a 2-D grating shape is shown as an example. As shown in FIG. 4C , a top-down view of an additional view of a 2-D grating is shown as an example. Examples of varying the plurality of grating structures 300 can include binary gratings, slanted gratings, blazed gratings, or generalized gratings (e.g., gratings with organic shapes). As described above, the plurality of grating structures 300 direct light away from the edge 116 of the substrate 102 toward the output coupler 108. The efficiency range of the plurality of grating structures 300 can range from about 0% to about 15%, but other values are contemplated. The variable grating efficiency can be achieved via a variable pitch, duty cycle, and / or depth of the plurality of grating structures 300.

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

[0027] As shown in FIG. 3C and FIG. 3D shown, the plurality of grating structures disposed on the second waveguide combiner 204 includes a duty cycle variation 304. FIG. 3D A cross-section along FIG. 3C is shown. The duty cycle is determined by dividing the critical dimension 304a (e.g., width) of the grating structures in the plurality of grating structures 300 by the pitch 304b (e.g., distance between first edges) of the grating structures. The duty cycle variation 304 is about 0.1 to about 0.9. The duty cycle variation 304 across the efficiency ramp EPE 206 affects the shape of the first and second bands 232, 234.

[0028] As shown in FIG. 3E and FIG. 3F shown, the plurality of grating structures 300 disposed on the second waveguide combiner 204 includes a pitch variation 306. FIG. 3F A cross-section along FIG. 3E is shown. The pitch variation 306 is defined by the distance between the first edges 306a of the plurality of grating structures 300. The pitch variation 306 is about -10 A to about 10 A. The pitch variation 306 across the efficiency ramp EPE 206 affects the shape of the first and second bands 232, 234.

[0029] As shown in FIG. 3G and FIG. 3H shown, the plurality of grating structures 300 disposed on the second waveguide combiner 204 includes a second variable depth 308. FIG. 3H A cross-section along FIG. 3G is shown. The second variable depth 308 forms the first band 232 (e.g., one band is formed on the efficiency ramp EPE 206) on the efficiency ramp EPE 206. The first band 232 is formed where the depth 308a is greater when compared to other areas on the grating, e.g., 308b.

[0030] As shown in FIG. 3I and FIG. 3J shown, the plurality of grating structures 300 disposed on the second waveguide combiner 204 includes a second pitch variation 310. FIG. 3J A cross-section along FIG. 3I is shown. The second pitch variation 310 includes a change in pitch 310a that forms the first band 232 (e.g., one band is formed on the efficiency ramp EPE 206). The first band 232 is formed where the pitch 310a varies when compared to other areas in the plurality of grating structures 300, e.g., pitch 310b.

[0031] As shown in FIG. 3K andFIG. 3L As shown, the plurality of grating structures disposed on the first waveguide combiner 202 includes a duty cycle variation 304. FIG. 3L A cross-section along the line F' to F'' is shown. The duty cycle is determined by dividing the critical dimension 304a (e.g., width) of the grating structures in the plurality of grating structures 300 by the pitch 304b (e.g., distance between first edges) of the grating structures. The duty cycle variation 304 is about 0.1 to about 0.9. The duty cycle variation 304 across the efficiency phased EPE 206 affects the shape of the first band 232 and the second band 234. FIG. 3K A cross-section along the line F' to F'' is shown. The duty cycle is determined by dividing the critical dimension 304a (e.g., width) of the grating structures in the plurality of grating structures 300 by the pitch 304b (e.g., distance between first edges) of the grating structures. The duty cycle variation 304 is about 0.1 to about 0.9. The duty cycle variation 304 across the efficiency phased EPE 206 affects the shape of the first band 232 and the second band 234.

[0032] The present disclosure provides a device with an efficiency phased EPE. The efficiency phased EPE facilitates multiple interactions with light as the light moves laterally within the EPE. The interactions direct the light away from a cutout region of the waveguide or EPE and toward an out-coupler. The cutout region can include an edge of the waveguide combiner or an edge of a substrate on which the waveguide combiner is disposed. The controlled direction of light within the efficiency phased EPE allows for a large user field of view (FOV), flexibility in layout design of the waveguide combiner, and makes the waveguide combiner lighter to allow for easy all-day wear by the user.

[0033] While the foregoing is directed to implementations of the present disclosure, other and further implementations of the disclosure can be devised without departing from the basic scope thereof, and the scope thereof is determined by the recited claims.

Claims

1. An apparatus comprising: Waveguide combiner, the waveguide combiner comprising: An input coupler, which is operable to receive light and couple the light input to the waveguide combiner; An exit pupil expander (EPE) adjacent to the grating of the input coupler, the EPE having a hierarchical structure, the hierarchical structure comprising at least one band, the at least one band comprising a plurality of grating structures, at least one of the grating structures having a varying depth, varying duty cycle, or varying pitch that differs from the depth, varying duty cycle, or varying pitch of adjacent grating structures in the grating structure; and An output coupler, operable to receive the light from the EPE and transmit the light to the user's field of view (FOV).

2. The apparatus according to claim 1, further comprising: An optical engine is disposed above the waveguide combiner and has a pupil located above the input coupler.

3. The apparatus of claim 1, wherein the grating structure includes the varying depth.

4. The apparatus of claim 1, wherein the grating structure includes the varying duty cycle.

5. The apparatus of claim 1, wherein the grating structure includes the varying pitch.

6. The apparatus according to claim 1, wherein the grating structure comprises a 1-D structure.

7. The apparatus of claim 1, wherein the grating structure comprises a 2-D structure.

8. The apparatus of claim 1, wherein the hierarchical structure is arranged across the EPE in a diagonal pattern.

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

10. The apparatus of claim 1, wherein the waveguide combiner includes a rounded edge portion.

11. The apparatus of claim 10, wherein a portion of the EPE conforms to the rounded edge portion.

12. The apparatus of claim 1, wherein the hierarchical structure has a grating efficiency value.

13. An apparatus comprising: substrate; A light engine, wherein the light engine is disposed above the substrate; A waveguide assembler disposed on the substrate, the waveguide assembler comprising: An input coupler, which is operable to receive light and couple the light input to the waveguide combiner; An exit pupil expander (EPE) adjacent to the grating of the input coupler, the EPE having a hierarchical structure, the hierarchical structure comprising at least one strip, the at least one strip comprising a plurality of grating structures, at least one of the grating structures having a varying depth, varying duty cycle or varying pitch that is different from the depth, varying duty cycle or varying pitch of the adjacent grating structures in the grating structure. as well as An output coupler, operable to receive light from the EPE and transmit the light to the user's field of view (FOV); and The user FOV is disposed adjacent to the waveguide combiner, and the user FOV is operable to receive the light from the waveguide combiner and display the light.

14. The apparatus of claim 13, wherein the EPE comprises at least two strips.

15. The apparatus of claim 10, wherein the hierarchical structure is arranged diagonally across the EPE.

16. The apparatus of claim 13, wherein the hierarchical structure has a grating efficiency value, the grating efficiency value being at least partially based on at least one of the pitch, the duty cycle, and the depth of the hierarchical structure.

17. A method comprising: An optical input is coupled to a waveguide combiner, the waveguide combiner comprising: An input coupler, which is operable to receive the light; An exit pupil expander (EPE) adjacent to the grating of the input coupler, the EPE having a hierarchical structure, the hierarchical structure comprising at least one strip, the at least one strip comprising a plurality of grating structures, at least one of the grating structures having a varying depth, varying duty cycle or varying pitch that is different from the depth, varying duty cycle or varying pitch of the adjacent grating structures in the grating structure. as well as Output coupler; The light is reflected at the EPE; The light within the EPE interacts with the grating structure; as well as The light is coupled at the output coupler, which is operable to receive the light from the EPE and transmit the light to the user's field of view (FOV).

18. The method of claim 17, further comprising: The light within the EPE interacts at multiple optical interaction points; and The light is guided away from the edge of the waveguide combiner of the EPE using the plurality of grating structures.

19. The method of claim 17, wherein a plurality of light beams are directed into the waveguide combiner.

20. The method of claim 17, wherein the hierarchical structure has a grating efficiency value, the grating efficiency value being at least partially based on at least one of the pitch, duty cycle, and depth of the grating structure.

Images