Waveguide display with grating with continuous phase shift

Abstract

A display may include a waveguide that directs image light to an eye-fit region. The waveguide may include an optical coupler that redirects and replicates light. The coupler may include a surface relief grating (SRG). The SRG may have a pitch that varies continuously along an axis orthogonal to its ridge. The pitch may vary sinusoidally, linearly, parabolically, or according to other continuous and differentiable functions of the position along the axis. The SRG may diffract light. When diffracting light, the SRG may impart a phase to the light. The phase may vary continuously as a function of position along the first axis and, if desired, may vary continuously as a function of position along a second axis orthogonal to the first axis. The SRG may prevent the formation of a coherent optical path after replication, thereby maximizing the efficiency of the system.

Description

[0001] This application claims priority to U.S. Patent Application No. 18 / 805,955, filed August 15, 2024, and U.S. Provisional Patent Application No. 63 / 583,085, filed September 15, 2023, each of which is incorporated herein by reference in its entirety. Background Technology

[0002] This disclosure relates to optical systems, such as optical systems in electronic devices having displays.

[0003] Electronic devices can include displays that provide images near a user's eyes. Such devices often include virtual reality or augmented reality headsets with displays having optical elements that allow the user to view the display. If not handled carefully, the components used to display the images can be bulky and may not exhibit the desired level of optical performance. For example, coherent light paths in the display can produce destructive interference that reduces the display's efficiency. Summary of the Invention

[0004] Electronic devices may include displays with waveguides that direct image light to the eye-friendly region. The waveguides may include optical couplers that redirect and reproduce the image light. The optical couplers may include one or more surface ripple gratings (SRGs). The SRGs may have a pitch that varies continuously along an axis orthogonal to the ridges of the SRG. This pitch may vary sinusoidally, linearly, parabolically, or according to other continuous and differentiable functions of position along the axis.

[0005] SRGs can diffract image light. In diffracting the image light, an SRG can impart phase to it. This phase can vary continuously as a function of position along a first axis, and, if desired, as a function of position along a second axis orthogonal to the first axis. An SRG can, for example, exhibit a parabolic or parabolic phase diagram. If desired, the ridges and grooves of the SRG can follow sinusoidal paths. This SRG prevents the formation of coherent light paths after replication, thereby maximizing system efficiency. Continuously changing the pitch or phase prevents the formation of ghosting artifacts in the image light associated with sharp boundaries between regions of different pitches or phases. Attached Figure Description

[0006] Figure 1 This is an illustration of an exemplary system with a display according to some implementation schemes.

[0007] Figure 2 This is a top view of an exemplary optical system for a display according to some embodiments, the optical system having a waveguide and an optical coupler.

[0008] Figures 3A to 3C This is a top view of an exemplary waveguide with a surface undulation grating according to some implementation schemes.

[0009] Figure 4 This is a front view of an exemplary waveguide having an optical coupler formed by a surface undulation grating, according to some implementation schemes.

[0010] Figure 5 This is a front view of an exemplary waveguide with an optical coupler according to some embodiments, the optical coupler having a first overlapping surface undulation grating and a second overlapping surface undulation grating oriented in different directions.

[0011] Figure 6 This is a front view illustrating how a surface undulation grating with a constant pitch can generate a coherent optical path in a pupil-replicating optical coupler according to some embodiments.

[0012] Figure 7 It is a front view of an exemplary surface undulation grating with a continuously varying pitch across its lateral region, according to some implementation schemes.

[0013] Figure 8 It is a front view of an exemplary surface undulation grating with ridges following a periodic path, according to some implementation schemes.

[0014] Figure 9 This is a drawing illustrating how an exemplary surface undulation grating, according to some embodiments, can have a pitch that varies continuously in a parabolic pattern across its lateral region.

[0015] Figure 10 This illustrates how an exemplary surface undulation grating, according to some embodiments, can impart a phase to a one-dimensional phase map of diffracted light that varies parabolically along a first axis.

[0016] Figure 11 This is a two-dimensional phase diagram illustrating how an exemplary surface undulation grating, according to some embodiments, can impart phase to diffracted light that varies parabolically along a first axis.

[0017] Figure 12 This illustrates how an exemplary surface undulation grating, according to some embodiments, can impart a phase to a one-dimensional phase diagram of diffracted light that varies parabolically along a second axis.

[0018] Figure 13 This is a two-dimensional phase diagram illustrating how an exemplary surface undulation grating, according to some embodiments, can impart phase to diffracted light that varies parabolically along a first orthogonal axis and a second orthogonal axis.

[0019] Figure 14 This illustrates the setup according to some implementation schemes. Figures 10 to 13The decomposed front view shows how the ridges of an exemplary surface undulation grating of the phase map type shown can follow a curved path. Detailed Implementation

[0020] Figure 1 System 10 may be a head-mounted device with one or more displays. The displays in system 10 may include a near-eye display 20 mounted within a support structure (housing) 14. The support structure 14 may be shaped like a pair of glasses or goggles (e.g., a support frame), may be formed with a helmet-shaped housing, or may have other configurations to help mount and secure components of the near-eye display 20 to the user's head or near their eyes. The near-eye display 20 may include one or more display projectors (such as projector 26 (sometimes referred to herein as display module 26)) and one or more optical systems (such as optical system 22). Projector 26 may be mounted within a support structure such as support structure 14. Each projector 26 may emit image light 30, which is redirected toward the user's eyes at an eye-friendly zone 24 using an associated optical system in optical system 22. Image light 30 may be, for example, light containing and / or representing visible things such as a scene or object (e.g., modulated onto the image light using image data provided to the display module by control circuitry).

[0021] The control circuit 16 can be used to control the operation of the system 10. The control circuit 16 may include storage and processing circuitry for controlling the operation of the system 10. The circuit 16 may include storage devices such as hard disk drive storage devices, non-volatile memory (e.g., electrically programmable read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random access memory), etc. The processing circuitry in the control circuit 16 may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, graphics processing units, application-specific integrated circuits (ASICs), and other integrated circuits. Software code may be stored on the memory in the circuit 16 and run on the processing circuitry in the circuit 16 to implement operations for the system 10 (e.g., data acquisition operations, operations involving the use of control signals to adjust components, image rendering operations to generate image content for display to a user, etc.).

[0022] System 10 may include input-output circuitry such as input-output device 12. Input-output device 12 may be used to allow system 10 to receive data from external equipment (e.g., a tethered computer, portable device (such as a handheld device or laptop computer), or other electrical equipment) and to allow user input to head-mounted device 10. Input-output device 12 may also be used to collect information about the environment in which system 10 (e.g., head-mounted device 10) operates. Output components in device 12 may allow system 10 to provide output to a user and may be used to communicate with external electronic equipment. Input-output device 12 may include sensors and other components 18 (e.g., image sensors, accelerometers, depth sensors, light sensors, haptic output devices, speakers, batteries, wireless communication circuitry for communication between system 10 and external electronic equipment, etc.).

[0023] Projector 26 may include a liquid crystal display, an organic light-emitting diode display, a laser-based display, or other types of display. Projector 26 may include a light source, an emissive display panel, a transmissive display panel illuminated by illumination light from the light source to produce image light, and a reflective display panel illuminated by illumination light from the light source to produce image light 30 (such as a digital micromirror display (DMD) panel and / or a liquid crystal on silicon (LCOS) display panel), etc.

[0024] Optical system 22 can form lenses that allow a viewer (see, for example, the viewer's eye at eye-adaptation zone 24) to view an image on display 20. Two optical systems 22 may be associated with the user's respective left and right eyes (e.g., for forming left and right lenses). A single display 20 can generate images for both eyes, or a pair of displays 20 can be used to display images. In a configuration with multiple displays (e.g., a left-eye display and a right-eye display), the focal length and position of the lenses formed by system 22 can be selected such that any gaps between the displays will be invisible to the user (e.g., allowing the images from the left and right displays to seamlessly overlap or merge).

[0025] If desired, optical system 22 may include components (e.g., optical combiners, etc.) to allow optical combination of real-world light 31 (sometimes referred to herein as world light 31 or ambient light 31) generated and / or reflected from real-world object 28 (sometimes referred to herein as external object 28) with virtual (computer-generated) images (such as virtual images in image light 30). In this type of system (sometimes referred to as an augmented reality system), the user of system 10 can view both real-world content and computer-generated content overlaid on the real-world content. Camera-based augmented reality systems may also be used in device 10 (e.g., in an arrangement where a camera captures a real-world image of an external object and digitally merges this content with virtual content at optical system 22).

[0026] If necessary, system 10 may include wireless circuitry and / or other circuitry to support communication with a computer or other external device (e.g., a computer that supplies image content to display 20). During operation, control circuitry 16 may provide image content to display 20. This content may be received remotely (e.g., from a computer or other content source coupled to system 10), and / or may be generated by control circuitry 16 (e.g., text, other computer-generated content, etc.). The content provided to display 20 by control circuitry 16 may be viewed by a viewer at eye level 24.

[0027] Figure 2 It is possible Figure 1 A top view of the exemplary display 20 used in system 10. (See figure) Figure 2 As shown, display 20 may include a projector such as projector 26 and an optical system such as optical system 22. Optical system 22 may include optical elements such as one or more waveguides 32. Waveguide 32 may include one or more stacked substrates (e.g., stacked planar and / or curved layers, sometimes referred to herein as waveguide substrates) of optically transparent materials such as plastics, polymers, glass, etc. Waveguide 32 may have a first side surface 37 and a second side surface 39 opposite to side surface 37. Side surfaces 37 and 39 are sometimes referred to herein as waveguide surfaces.

[0028] If desired, waveguide 32 may also include one or more layers of holographic recording medium (sometimes referred to herein as a "holographic medium," "grating medium," or "diffraction grating medium") on which one or more diffraction gratings (e.g., holographic phase gratings, sometimes referred to herein as "holograms," surface undulation gratings, etc.) are recorded. The holographic record may be stored as an optical interference pattern (e.g., alternating regions of different refractive indices) within a photosensitive optical material such as the holographic medium. This optical interference pattern can generate a holographic phase grating, which, when illuminated with a given light source, diffracts light to form a three-dimensional reconstruction of the holographic record. The holographic phase grating may be a non-switchable diffraction grating encoded with a permanent interference pattern, or it may be a switchable diffraction grating where the diffracted light can be modulated by controlling the electric field applied to the holographic recording medium. If desired, multiple holographic phase gratings (holograms) may be recorded within the same volume of the holographic medium (e.g., superimposed within a grating medium of the same volume). The holographic phase grating can be, for example, a volume hologram or a thin-film hologram in a grating medium. The grating medium may include photopolymers, gelatin such as dichromate gelatin, silver halide, holographic polymer-dispersed liquid crystals, or other suitable holographic media.

[0029] The diffraction grating on waveguide 32 may include holographic phase gratings such as volumetric holograms or thin-film holograms, meta-gratings, or any other desired diffraction grating structure. The diffraction grating on waveguide 32 may also include surface undulation gratings (SRGs) formed on one or more surfaces of a substrate in waveguide 32 (e.g., modulation of the thickness of the SRG dielectric layer), gratings formed by patterns of metallic structures, etc. The diffraction grating may, for example, include multiple multiplexed gratings (e.g., holograms) that at least partially overlap within a grating dielectric of the same volume (e.g., for diffracting light of different colors and / or light from different input angle ranges at one or more corresponding output angles). If desired, other light redirection elements such as venetian blinds may be used instead of the diffraction grating in waveguide 32.

[0030] like Figure 2 As shown, projector 26 can generate (e.g., produce and emit) image light 30 associated with image content to be displayed to eye-friendly area 24 (e.g., image light 30 can convey a series of image frames for display at eye-friendly area 24). If desired, the image light 30 can be collimated using a collimating lens in projector 26. Optical system 22 can be used to present the image light 30 output from projector 26 to eye-friendly area 24. If desired, projector 26 can be mounted on... Figure 1 The optical system 22 can be mounted within the support structure 14, and can be mounted between various parts of the support structure 14 (e.g., to form a lens aligned with the eye zone 24). Other mounting arrangements may be used if desired.

[0031] Optical system 22 may include one or more optical couplers (e.g., light redirection elements) such as input coupler 34, cross coupler 36, and output coupler 38. Figure 2 In the example, input coupler 34, cross coupler 36, and output coupler 38 are formed at or on waveguide 32. Input coupler 34, cross coupler 36, and / or output coupler 38 may be fully embedded within the substrate layer of waveguide 32, partially embedded within the substrate layer of waveguide 32, or mounted to waveguide 32 (e.g., mounted to the outer surface of waveguide 32), etc.

[0032] Waveguide 32 can guide image light 30 along its length via total internal reflection. Input coupler 34 can be configured to couple image light 30 from projector 26 into waveguide 32 (e.g., within the total internal reflection (TIR) ​​range of the waveguide, where light propagates along the waveguide via TIR), while output coupler 38 can be configured to couple image light 30 from within waveguide 32 (e.g., propagating within the TIR range) to the outside of waveguide 32 and toward eye-friendly region 24 (e.g., at an angle outside the TIR range). Input coupler 34 may include an input coupling prism, an edge or face of waveguide 32, a lens, a steering mirror or liquid crystal steering element, a diffraction grating structure (e.g., a volume hologram, SRG, etc.), a partial reflection structure (e.g., a venetian blind), or any other desired input coupling element.

[0033] For example, projector 26 can emit image light 30 toward optical system 22 in the +Y direction. When image light 30 strikes input coupler 34, input coupler 34 can redirect image light 30 such that the light propagates within waveguide 32 via total internal reflection toward output coupler 38 (e.g., in the +X direction within the TIR range of waveguide 32). When image light 30 strikes output coupler 38, output coupler 38 can redirect image light 30 toward eye-friendly region 24 (e.g., rearward along the Y-axis) away from waveguide 32. In a specific implementation where cross coupler 36 is formed on waveguide 32, cross coupler 36 can redirect image light 30 in one or more directions as it propagates downward along the length of waveguide 32 (e.g., from the propagation direction coupled from the input coupler into the waveguide toward output coupler 38). When redirecting image light 30, cross coupler 36 can also perform pupil expansion of image light 30 in one or more directions. When expanding the pupil of the image light, the cross-coupler 36 can, for example, help reduce the vertical size of the waveguide 32 (e.g., in the Z direction) compared to a specific implementation that omits the cross-coupler 36. Therefore, the cross-coupler 36 may sometimes be referred to herein as a pupil expander 36 or an optical expander 36. If desired, the output coupler 38 can also expand the image light 30 when coupling the image light out of the waveguide 32.

[0034] Input coupler 34, cross coupler 36, and / or output coupler 38 may be based on reflective and refractive optics, or on diffractive (e.g., holographic) optics. In an arrangement where couplers 34, 36, and 38 are formed by reflective and refractive optics, couplers 34, 36, and 38 may include one or more reflectors (e.g., micromirrors, partial mirrors, venetian blinds, or arrays of other reflectors). In an arrangement where couplers 34, 36, and 38 are based on diffractive optics, couplers 34, 36, and 38 may include diffraction gratings (e.g., volumetric holograms, surface undulation gratings, etc.).

[0035] Figure 2 The examples provided are merely illustrative. Optical system 22 may include multiple waveguides stacked laterally and / or vertically relative to each other. Each waveguide may include one, two, all, or none of the couplers 34, 36, and 38. Waveguide 32 may be at least partially curved or bent if desired. One or more of couplers 34, 36, and 38 may be omitted. Optical system 22 may include a single optical coupler (sometimes referred to herein as an interleaved coupler, diamond coupler, or diamond extender) that performs the operation of both cross coupler 36 and output coupler 38, or cross coupler 36 may be separate from output coupler 38. Specific implementations of surface undulation gratings (SRGs) are described herein as examples of cross coupler 36 or a single optical coupler that performs the operation of both cross coupler 36 and (e.g., receiving light from an input coupler) output coupler 38.

[0036] Figure 3A This is a top view illustrating an example of how a surface-roughened grating structure can be formed on waveguide 32. (See image.) Figure 3A As shown, waveguide 32 may have a first side surface 70 and a second side surface 72 opposite to the side surface 70 (sometimes referred to herein as waveguide surfaces). Waveguide 32 may include any desired number of one or more stacked waveguide substrates. If desired, waveguide 32 may also include a layer of grating medium sandwiched (intercalated) between the first waveguide substrate and the second waveguide substrate (e.g., where the first waveguide substrate includes side surface 70 and the second waveguide substrate includes side surface 72).

[0037] Waveguide 32 may be provided with a surface undulation grating (SRG), such as surface undulation grating 74. For example, SRG 74 may be included in cross coupler 36 or as part of an optical coupler (e.g., a rhombus expander or interleaved coupler) that performs the operation of both cross coupler 36 and output coupler 38. SRG 74 may be formed within a substrate (such as a layer of SRG substrate 76, sometimes referred to herein as dielectric 76, dielectric layer 76, SRG dielectric 76, or SRG dielectric layer 76)). Although for clarity, Figure 3A Only a single SRG 74 is shown in the SRG substrate 76, but the SRG substrate 76 may include two or more SRGs 74 (e.g., SRGs with different corresponding grating vectors). If desired, at least a portion of each SRG may be stacked within the same volume of the SRG substrate 76. Figure 3A In the example, the SRG substrate 76 is stacked on the side surface 70 of the waveguide 32. This is merely illustrative, and if desired, the SRG substrate 76 may be stacked on the side surface 72 (e.g., the surface of the waveguide 32 facing the eye region).

[0038] SRG 74 may include peaks 78 and grooves 80 in the thickness of the SRG substrate 76. Peak 78 may also be referred to herein as ridge 78 or highest value 78. Groove 80 may also be referred herein as notch 80, slot 80, recess 80, or minimum value 80. Figure 3A In the example, for clarity, SRG 74 is illustrated as a binary structure, wherein SRG 74 is defined by a first thickness associated with ridge 78 or a second thickness associated with slot 80. This is merely illustrative. If desired, SRG 74 can be non-binary (e.g., may include any desired amount of thickness following any desired profile, may include ridge 78 angled relative to the Y-axis at a non-parallel stripe angle, etc.), may include ridge 78 with a sloping surface (e.g., oriented outside the XZ plane), may include sloping slot 80 (e.g., oriented outside the XZ plane), may include ridge 78 and / or slot 80 with a height and / or depth following the modulation wave envelope, etc. If desired, SRG substrate 76 may be adhered to the side surface 70 of waveguide 32 using a layer of optically transparent adhesive (not shown). For example, SRG 74 may be manufactured separately from waveguide 32 and may be adhered to waveguide 32 after manufacturing, or may be etched into SRG substrate 76 after SRG substrate 76 has been laminated on waveguide 32.

[0039] Figure 3A The example provided is merely illustrative. In another specific implementation, the SRG 74 may be placed at a location inside the waveguide 32, such as... Figure 3B As shown in the example. Figure 3B As shown, waveguide 32 may include a first waveguide substrate 84, a second waveguide substrate 86, and a dielectric layer 82 interposed between the waveguide substrate 84 and the waveguide substrate 86. The dielectric layer 82 may be a grating or holographic recording medium, a layer of adhesive, a polymer layer, a layer of the waveguide substrate, or any other desired layer within the waveguide 32. An SRG substrate 76 may be laminated onto the surface of the waveguide substrate 84 facing the waveguide substrate 86. Alternatively, the SRG substrate 76 may be laminated onto the surface of the waveguide substrate 86 facing the waveguide substrate 84.

[0040] If needed, multiple SRG 74s can be distributed across multiple layers of the SRG substrate, such as... Figure 3C As shown in the example. Figure 3C As shown, the optical system may include multiple stacked waveguides, such as at least a first waveguide 32 and a second waveguide 32'. A first SRG substrate 76 may be stacked on one of the side surfaces of waveguide 32, while a second SRG substrate 76' may be stacked on one of the side surfaces of waveguide 32'. The first SRG substrate 76 may include one or more SRGs 74. The second SRG substrate 76' may include one or more SRGs 74. This example is illustrative only. If desired, the optical system may include more than two stacked waveguides. In examples where the optical system includes more than two waveguides, each waveguide with an SRG substrate may include one or more SRGs 74. Although described herein as individual waveguides, if desired, Figure 3C Waveguides 32 and 32' can also be formed from corresponding waveguide substrates of the same waveguide. If necessary, they can be... Figure 3A , 3B Combined with / or the arrangement in 3C.

[0041] If desired, waveguide 32 may include one or more substrates having regions including diffraction gratings for input coupler 34, cross coupler 36 and / or output coupler 38 and regions without diffraction gratings. Figure 4 This is a front view illustrating an example of how waveguide 32 may include one or more substrates having regions including diffraction gratings for input coupler 34, cross coupler 36, and / or output coupler 38, and regions without diffraction gratings.

[0042] like Figure 4 As shown, waveguide 32 may include one or more substrates 89 (e.g., a single substrate 89 or multiple stacked substrates 89) on one or more waveguides 32 (e.g., a single waveguide 32 or multiple stacked waveguides 32). Substrate 89 may include one or more layers of grating medium, such as SRG substrate 76 (…). Figures 3A to 3B One or more diffraction grating structures 88 for forming the optical coupler of waveguide 32 may be disposed or formed in substrate 89. Each diffraction grating structure 88 may include one or more SRG 74 ( Figures 3A to 3C ).

[0043] For example, substrate 89 may include a first group of one or more overlapping SRG 74s in a first region of substrate 89. Figures 3A to 3CThe substrate 89 may further include a first diffraction grating structure 88A (sometimes referred to herein as grating structure 88A or grating 88A) formed by a second set of one or more overlapping SRGs 74 in a second region of the substrate 89, which is laterally separated from the first diffraction grating structure 88A. If desired, the substrate 89 may further include a third diffraction grating structure 88C (sometimes referred to herein as grating structure 88C or grating 88C) formed by a third set of one or more overlapping SRGs 74 in a third region of the substrate 89, which is laterally separated from the first diffraction grating structure 88A and the second diffraction grating structure 88B.

[0044] Diffraction grating structures 88A, 88B, and 88C can each form a corresponding optical coupler for waveguide 32. For example, diffraction grating structure 88A can form an input coupler 34 for waveguide 32. Diffraction grating structure 88B can form a cross-coupler (e.g., a pupil expander) 36 on waveguide 32. Diffraction grating structure 88C can form an output coupler 38 for waveguide 32. Thus, diffraction grating structure 88A can couple the image light beam 92 of 30 into waveguide 32 and toward diffraction grating structure 88B. Diffraction grating structure 88B can redirect the image light 30 toward diffraction grating structure 88C and can optionally perform pupil expansion on the image light 30 (e.g., splitting the image light 30 into multiple paths to form a larger beam that covers the eye pupil and forms a more uniform image). Diffraction grating structure 88C can couple the image light 30 out of waveguide 32 and toward the eye-friendly region. If needed, the diffraction grating structure 88C can also perform pupil expansion on the image light 30.

[0045] The substrate 89 and therefore the waveguide 32 may also include one or more regions 90 that do not contain a diffraction grating structure 88, a diffraction grating, or an optical coupler. For example, region 90 may not contain any ridges 78 and grooves 80 of an SRG. Figures 3A to 3C Furthermore, if desired, refractive index modulation without VPH is possible. Region 90 may separate diffraction grating structure 88A from diffraction grating structure 88B, diffraction grating structure 88B from diffraction grating structure 88C, diffraction grating structure 88C from diffraction grating structure 88A, and / or may laterally surround one or all of the diffraction grating structures 88A-C. Region 90 may sometimes be referred to herein as grating-free region 90, inter-grating region 90, non-grating region 90, or non-diffraction region 90. Non-diffraction region 90 may, for example, include all lateral regions of the lateral region of substrate 89 excluding diffraction gratings.

[0046] Each diffraction grating structure 88 in substrate 89 may span a corresponding lateral region of substrate 89. The lateral region spanned by each diffraction grating structure 88 is defined by a lateral edge 94 of that diffraction grating structure 88. The lateral edge 94 may separate or isolate a portion of substrate 89, including thickness modulation for forming one or more SRGs in the diffraction grating structure 88, from a non-diffraction region 90 on substrate 89. In other words, the lateral edge 94 may define the boundary between the diffraction grating structure 88 and the non-diffraction region 90. Diffraction grating structures 88A, 88B, and 88C may have any desired lateral shape (e.g., as defined by the lateral edge 94).

[0047] Figure 4 The examples provided are merely illustrative, and in general, the input coupler 34, cross coupler 36, and output coupler 38 may have any desired lateral profile or shape (e.g., as defined by lateral edge 94). If desired, waveguide 32 may include an optical coupler that both redirects and expands / reproduces the image light 30 (e.g., to fill the largest possible eye-friendly area 24 with image light 30 of the most uniform intensity possible). Such an optical coupler (sometimes referred to herein as a diamond expander or cross coupler) performs the functionality of both cross coupler 36 and output coupler 38. By using an optical coupler as both a cross coupler and an output coupler, space within the display can be saved (e.g., space that would otherwise be occupied by separate cross couplers and output couplers).

[0048] Figure 5 This is a front view of such an optical coupler 109 on waveguide 32. The optical coupler 109 may, for example, replace... Figure 4 The cross-coupler 36 and output coupler 38 on waveguide 32. For example... Figure 5 As shown, the optical coupler 109 may include a diffraction grating structure 88D having at least a first SRG 74A and a second SRG 74B on a substrate 89 (e.g., superimposed on each other in the same volume of a single substrate 89). Each of the SRG 74A and SRG 74B may include a corresponding set of ridges 78 and grooves 80 extending in the substrate 89 and in different respective orientations. Figures 3A to 3C For example, SRG 74A can be characterized by a first grating vector K1 (e.g., orthogonally oriented to the direction of a line with peaks, grooves, or a constant dielectric thickness in SRG 74A). Similarly, SRG 74B can be characterized by a second grating vector K2 (e.g., orthogonally oriented to the direction of a line with peaks, grooves, or a constant dielectric thickness in SRG 74B). The grating vector K2 may be non-parallel to the grating vector K1.

[0049] The magnitude of grating vector K1 corresponds to the width and spacing (e.g., period) of the ridges 78 and grooves 80 (fringe) in SRG 74A, and to the wavelength of the light diffracted by the SRG. The magnitude of grating vector K2 corresponds to the width and spacing (e.g., period) of the ridges 78 and grooves 80 in SRG 74B, and to the wavelength of the light diffracted by the SRG. Surface undulation gratings typically have a wide bandwidth. For example, the bandwidth of SRG 74A and SRG 74B may encompass every wavelength in the image light 30 (e.g., the entire visible spectrum, a portion of the visible spectrum, a portion of the infrared or near-infrared spectrum, a portion or all of the visible spectrum, and a portion of the infrared or near-infrared spectrum, etc.). The magnitude of grating vector K2 may be equal to or different from the magnitude of grating vector K1. Although for clarity, in Figure 5 The page is illustrated in a plane, but the raster vectors K1 and / or K2 may have non-zero vector components parallel to the Y-axis (e.g., the raster vectors K1 and K2 may be tilted inside or outside the page).

[0050] SRG 74A at least partially overlaps with SRG 74B in optical coupler 109 (e.g., at least a portion of the ridges and grooves of each SRG spatially overlaps or is superimposed within the same volume of the SRG substrate). If desired, the intensity of SRG 74A and / or SRG 74B can be modulated along a vertical direction (e.g., along the Z-axis) and / or along a horizontal direction (e.g., along the X-axis). If desired, one or both of SRG 74A and SRG 74B can have a value reduced to zero within the peripheral regions 108A and 108B of the field of view, which can help mitigate the generation of rainbow artifacts.

[0051] Input coupler 34 ( Figure 2 Image light 30 can be coupled into waveguide 32, which delivers the image light to optical coupler 109 via waveguide 32 (e.g., via total internal reflection). SRG 74A and SRG 74B can diffract the incident image light 30 in two different directions, thereby replicating the pupil of the image light. SRG 74A and SRG 74B can additionally or alternatively extend and / or replicate the pupil of the image light. This creates multiple optical paths for image light 30 within optical coupler 89 and ensures that the largest possible eye-friendly area is filled with image light 30 of uniform intensity.

[0052] SRG 74A and SRG 74B can be formed in the same layer of the SRG substrate 76, or they can be disposed in separate layers of the SRG substrate disposed on opposite side surfaces of the waveguide 32 or substrate 89. In another suitable embodiment, the waveguide 32 or substrate 89 includes a first SRG substrate layer on a first side surface and a second SRG substrate layer on a second side surface opposite to the first side surface, wherein the first SRG substrate layer includes SRG 74A and SRG 74B, and the second SRG substrate layer includes additional overlapping / crossing SRGs, such as SRG 74A and SRG 74B.

[0053] One or more SRGs on waveguide 32 (e.g., Figure 5 The SRG 74A and SRG 74B, Figure 4 One or more SRGs (such as optical couplers 88A, 88B, and / or 88C) can perform pupil replication on image light 30 propagating along waveguide 32. Pupil replication involves splitting the incident beam of image light 30 into two distinct optical paths as it propagates along the optical coupler. If not careful, pupil replication by the SRG can produce an undesirable coherent optical path for image light 30. Figure 6 This is a front view showing an example of how the SRG 74 can perform pupil copying.

[0054] like Figure 6 As shown, image light 30 is incident on SRG 74 in a first direction and propagates along waveguide 32 via TIR. When the image light first strikes SRG 74 (e.g., at point 114 in the first TIR bounce of SRG 74 / leaving the SRG), SRG 74 diffracts some of the image light in a second direction, as indicated by arrow 112, while the remainder of the image light continues to propagate in the first direction (e.g., without diffraction), as indicated by arrow 110. When the undiffracted light strikes the SRG substrate again (e.g., in the second TIR bounce), SRG 74 again diffracts some of the image light in the second direction (e.g., to point 116), while the remainder of the image light continues to propagate in the first direction. Simultaneously, when the light diffracted in the direction of arrow 112 in the first TIR bounce at point 114 strikes the SRG substrate again (e.g., in the second TIR bounce), SRG 74 again diffracts some of the image light in the second direction, while the remainder of the image light continues to propagate in the first direction (e.g., to point 116). As the image light 30 continues to propagate along the waveguide 32 via the TIR, this replication of the light path can continue across the lateral regions of the SRG 74 (e.g., producing a large number of replicates of the image light 30 in the pupil to fill the largest possible eye-friendly area with the most uniform amount of image light).

[0055] SRG 74 is characterized by the corresponding grating pitch P. Pitch P is defined by the lateral distance / separation between adjacent ridges 78 at the surface of the corresponding SRG substrate. SRG 74 is also characterized by a grating vector oriented in direction r, which is orthogonal to the ridges 78 (e.g., orthogonal to a line of constant SRG substrate thickness in SRG 74). The spatial position along direction r is sometimes referred to herein as position R.

[0056] In some implementations, the pitch P across the lateral region of SRG 74 is constant. In these implementations, the diffraction of image light 30 by SRG 74 causes the image light 30 to follow two optical / optical paths of nearly equal path length, which are then recombine (e.g., a first path from point 114 to point 116 via arrow 110 and then arrow 112, and a second path from point 114 to point 116 via arrow 112 and then arrow 110). This effectively creates a network of Mach-Zehnder interferometers across the lateral region of SRG 74. If the phase relationship between the image light following the first path and the image light following the second path is not strictly controlled, the phase difference between the first and second paths can produce destructive interference when the light from the first path and the light from the second path are recombinated at point 116. Destructive interference can reduce the amount of image light 30 reaching the eye-friendly region, thereby limiting the modulation transfer function (MTF) and / or efficiency of the display. Therefore, the relative phase between optical paths in the SRG 74 is to be controlled in a manner that minimizes destructive interference and thus maximizes spatial uniformity and angular image uniformity in the eye-friendly region.

[0057] To maximize spatial and angular image uniformity at the eye-friendly region, the SRG 74 can be configured to have different first and second path lengths (e.g., from point 114 to point 116) (e.g., across all regions of the SRG 74 used for pupil replication). One way to achieve this is by perturbing (e.g., chirping) the phase of the SRG, and thus perturbing imparts phase to the image light diffracted by the SRG over the pupil replication region. The SRG 74 can, for example, have a pitch P and / or an angle that varies (chirps) by a small percentage spatially across its lateral regions, causing the ridges of the SRG to slide in and out of phase relative to a constant-pitch SRG.

[0058] Figure 7 This illustrates how the SRG 74 can provide a front view showing a spatially varying pitch P across its lateral regions. (See diagram below.) Figure 7 As shown, the SRG 74 may have a ridge 78 and a groove 80, which are characterized by a pitch P and are oriented orthogonally to the direction r. The SRG 74 has a length L0 in the direction r.

[0059] As shown by SRG 74, SRG 74 has a variable pitch P that varies from a maximum pitch P2 to a minimum pitch P1 at a spatial position R along the direction r. For comparison, Figure 7 Part 120 illustrates the ridge 78 of the SRG, which has a constant pitch P0 at all spatial locations R along the direction r from R = 0 to R = L0. The parallel ridges in part 120 are defined by a first vector K oriented in the direction of the ridge. 平行 and orthogonal to vector K 平行 The second vector K (e.g., oriented perpendicular to the ridge direction) 垂直 Characterization. Section 120 illustrates examples of any modulation without grating angle or pitch (e.g., without modulation along vector K). 平行 or vector K 垂直 (Any phase shift). As shown by section 120 and SRG 74, ridge 78 in SRG 74 is along direction r and in vector K 垂直 It chirps (changes) spatially and periodically in the direction of the chirping.

[0060] Figure 7 Figure 122 plots the pitch of the SRG 74 at different positions R along the direction r (e.g., from R = 0 to R = L0). In some specific implementations, the pitch of the SRG 74 varies discretely (e.g., discontinuously) between regions with pitch P1 and regions with pitch P2, as shown by square waveform 126. However, discretely varying the pitch of the SRG 74 may limit the MTF of the SRG and may produce unsightly ghosting artifacts for the pupil of the image light 30 incident on the boundary between the discrete regions with pitch P1 and the discrete regions with pitch P2.

[0061] To alleviate these problems, SRG 74 can be provided with position R and vector K along direction r. 垂直 The pitch P of the SRG 74 varies continuously as a function of R (e.g., it varies smoothly without discrete or non-differentiable jumps in pitch P from R = 0 to R = L0). In other words, the pitch P of the SRG 74 varies / changes continuously or chirps continuously as a function of spatial position. If desired, the pitch P of the SRG 74 can vary continuously as a function of position R between pitches P1 and P2 in a periodic manner. For example, the pitch P can vary sinusoidally between pitches P1 and P2 from R = 0 to R = L0, as shown by curve 128. Unlike the square waveform 126, curve 128 is continuous and differentiable at all points between R = 0 and R = L0, thereby mitigating the formation of ghosting artifacts and maximizing MTF.

[0062] Ideally, the pitch P is spatially chirped by a percentage that makes the SRG relative to a constant pitch P0 (see [reference]). Figure 7 Part 120) slides in phase and out phase by up to 2π radians (e.g., a pitch deviation). This type of pitch modulation imparts a phase shift to the first-order diffracted light relative to light incident at other locations. This modulation is defined by the equation f(x) = P + ΔP(R), where ΔP(R) = (π... P / Λ) sin(2π R / Λ) where Λ is the period of pitch chirp, defined as the distance the grating line (ridge 78) is shifted, accumulating the positive grating period, and then accumulating the negative grating period. The average pitch of SRG 74 from R = 0 to R = L0 remains the same as the nominal design pitch (e.g., pitch P0).

[0063] Figure 7 The example illustrates two complete sinusoidal pitch chirp cycles (Λ) of the SRG 74. The sinusoidal variation of the pitch P (e.g., as given by curve 128) in Figure 7 The SRG 74 is depicted in an exaggerated form to help illustrate this variation. In practice, this 2π phase shift is applied to the SRG over millimeter-scale distances, becoming a subtle perturbation to the spacing of the ridge 78 across position R. Λ should be large enough that pitch modulation minimizes the trailing effect and MTF influence (e.g., 1–20 mm or other values ​​depending on the pupil spacing distance, waveguide thickness, and TIR angle). The SRG 74 can exhibit a continuously varying or chirped pitch P only in the region where the SRG 74 performs pupil replication to minimize the influence on MTF.

[0064] Figure 7 The examples provided are merely illustrative. In general, the pitch P can be continuously modulated or varied between R=0 and R=L0 in any desired manner. For example, the pitch P can vary continuously between pitches P1 and P2 in a linear manner (as shown by curve 130), a parabolic manner, a hyperbolic manner, or according to any desired continuous and differentiable function that, as a function of position R, varies continuously between pitches P1 and P2 from R=0 to R=L0. This function does not need to be periodic, but can be periodic if desired (e.g., sinusoidal). Parabolic variations can, for example, help improve spatial uniformity while introducing less MTF reduction than other variations.

[0065] exist Figure 7 In the example, the ridge 78 and slot 80 of SRG 74 are linear and are straight lines orthogonal to the direction r (vector K). 垂直 Extending upwards. In other words, ridge 78 and therefore... Figure 7The SRG 74 exhibits a constant angle, but with continuously changing / variable (modulated) pitch along vector K. 垂直 Changing the phase. This is merely illustrative. Additionally or alternatively, the ridge 78 and slot 80, and thus the SRG 74, can exhibit continuously changing / variable (modulated) angles (e.g., following a non-linear bending path) to further maximize the MTF. Figure 8 This is a front view illustrating an example of how the ridge 78 and slot 80 in the SRG 74 can exhibit continuously changing / variable angles but a constant pitch.

[0066] For comparison, Figure 8 Part 120 illustrates ridge 78 following a linear path (e.g., parallel to arrow 132), where there is no pitch modulation (e.g., no modulation along vector K). 垂直 (phase change) and no angular modulation (e.g., no modulation along vector K) 平行 (Phase changes). For example, by Figure 8 As shown in SRG 74, the positions of the ridge 78 and slot 80 of SRG 74 can vary by different amounts 134 along the direction of arrow 132 from a line parallel to arrow 132 (e.g., it can represent a change in the grating angle, and thus along the vector K). 平行 (The phase of the change). In other words, the ridges 78 and slots 80 of the SRG 74 can follow a non-linear path (e.g., a curved path), such as a sinusoidal path along the direction of arrow 132. The amplitude of the SRG 74 may not be greater than the pitch of the SRG. The sinusoidal periodicity of the path followed by the ridges 78 and slots 80 (e.g., along arrow 132) can be on the order of millimeter-scale pupil spacing. If desired, this periodicity can be varied in the lateral regions of the grating.

[0067] exist Figure 8 In the example, for clarity, SRG 74 is illustrated as having a constant pitch P. This is merely illustrative, and if desired, ridge 78 and slot 80 may also follow nonlinear (bending) paths (e.g., sinusoidal paths) (e.g., using any of the variable pitches described herein, such as those described herein) in addition to having continuously varying (chirped) pitches over the lateral regions across SRG 74. Figure 7 Sine variable pitch, Figure 7 (e.g., linear variable pitch, parabolic variable pitch, etc.). In other words, the SRG 74 can have a continuously varying pitch (e.g., as shown in the image). Figure 7 The following is along vector K 垂直 (Changing / modulating phase) and continuously changing angles (e.g., such as) Figure 8 The following is along vector K 平行 (Changing / modulating the phase) Both. When combined, in vector K垂直 and K 平行 The orthogonal components of continuous phase changes in the direction can produce any arbitrary phase pattern for the SRG 74. The following examples illustrate several exemplary and non-limiting phase patterns of interest to the SRG.

[0068] Figure 9 Curve 136 illustrates an example of how the pitch of the SRG 74 can vary continuously in a parabolic pattern (e.g., to improve spatial uniformity while introducing less MTF reduction). As shown by curve 136, the pitch P of the SRG 74 can be given by a parabola at position R, which has a minimum value equal to pitch P1 and a maximum value equal to pitch P2. The minimum value of the parabola can be at half the length of the SRG 74 (e.g., at R = L0 / 2). Alternatively, the parabola can be shifted or offset relative to the spatial center of the SRG 74 (e.g., such that the minimum value is located at a position R other than R = L0 / 2), as shown by curve 137. Alternatively, curve 136 or curve 137 can be reversed (e.g., the SRG 74 can have a maximum pitch P2 at position R = L0 / 2 and a minimum pitch P1 at positions R = 0 and R = L0).

[0069] Figure 10 It is a one-dimensional phase diagram that shows the pitch P of the parabolic change (e.g., Figure 9 (As shown) how to impart different phase shifts to image light 30 at different locations along a first spatial axis (e.g., axis X). SRG 74 may have a first dimension (e.g., length) L1 along axis X. Curve 138 plots the phase shift when the SRG has... Figure 9 Curve 136, with its parabolic variation in pitch P, imparts phase to the image light 30 during SRG diffraction at different positions along the axis X. Curve 139 plots the phase of the image light 30 when the SRG has a phase variation with pitch P. Figure 9 When the parabolic pitch P of curve 137 changes, it imparts a phase to the image light 30 at different positions along the axis X by diffraction by the SRG. In other words, the parabolic chirp of phase P across position R in SRG 74 configures SRG 74 to exhibit a corresponding parabolic phase diagram along the axis X (e.g., imparting different phases or phase shifts to the diffracted image light 30, as given by curve 138).

[0070] Figure 11 It is a two-dimensional phase diagram that shows how the SRG 74 can impart different phase shifts to the image light 30 at different spatial locations when the SRG 74 has a pitch P that varies parabolically only along a single axis. Figure 11Line 140 is a line that imparts a constant phase to the diffracted light at different two-dimensional spatial locations (e.g., in the XZ plane). Along one dimension (e.g., as...) Figure 10 The parabolic pitch of the axis X shown, and the resulting phase, cause the SRG 74 to exhibit a line with a constant phase parallel to the Z-axis, wherein the phase parabolically changes from the minimum phase within the central region 142 to the maximum phase within the outer region 144. In this way, Figure 10 The one-dimensional phase distribution allows the SRG 74 to be configured to exhibit a cylindrical two-dimensional phase map (e.g., imparting a cylindrical phase distribution to the image light across the XZ plane). This can, for example, configure the SRG 74 to form a cylindrical lens for the image light.

[0071] If needed, in addition to the X-axis, the SRG 74 can also exhibit a parabolic phase distribution along the Z-axis (e.g., by parabolically changing the pitch P, as by...). Figure 9 As shown in curves 136 or 137, but along an axis that is not parallel to direction r. Figure 12 It is a one-dimensional phase diagram that shows the pitch P (e.g., along an axis that is not parallel to the direction r) as a parabola. Figure 9 (As shown) How to impart different phase shifts to image light 30 at different positions along a second spatial axis (e.g., axis Z) orthogonal to axis X. SRG 74 may have a second dimension (e.g., width) L2 along axis Z.

[0072] Curve 146 plots the phase imparted to the image light 30 by diffraction at different locations along the Z-axis when the SRG has a pitch P with a parabolic variation along the Z-axis and centered along the Z-axis (e.g., at L2 / 2). Curve 148 plots the phase imparted to the image light 30 by diffraction at different locations along the Z-axis when the SRG has a pitch P with a parabolic variation along the Z-axis, offset from the center of the width L2. In other words, the parabolic chirp of phase P across the axis orthogonal to direction r in the SRG 74 configures the SRG 74 to exhibit a corresponding parabolic phase diagram along the Z-axis (e.g., imparting different phases or phase shifts to the diffracted image light 30, as given by curve 146). When compared with the parabolic phase diagram along the X-axis (e.g., as given by curve 146), the phase imparted to the image light 30 by diffraction at different locations along the Z-axis is also considered. Figure 10 When combined with the curve 138 given, SRG 74 can exhibit a parabolic phase distribution (Figure 138).

[0073] Figure 13 This is a two-dimensional phase diagram showing how the SRG 74 can represent a parabolic phase distribution (Figure). Figure 13Curve 154 is a curve that imparts a constant phase to the diffracted light at different two-dimensional spatial locations (e.g., in the XZ plane). The phase is parabolically changed along the X-axis (as by...). Figure 10 (As shown in curve 138) it also parabolically changes phase along the Z-axis (as shown by...) Figure 10 (As shown by curve 146) causes the SRG 74 to exhibit a circle or ellipse with constant phase around the central region 152 (e.g., at Z = L2 / 2 and X = L1 / 2), where the phase parabolically changes from the minimum phase in the central region 152 to the maximum phase in the peripheral region 150. In this way, the SRG 74 can exhibit a parabolic phase distribution across its lateral regions (e.g., in the XZ plane) (Figure). This can, for example, configure the SRG 74 to form a lens (e.g., a parabolic lens) that imparts diopter to the image light 30. Simultaneously, the phase distribution can minimize the coherent light path in the SRG 74 and / or maximize the MTF. Figures 9 to 13 The examples are merely illustrative, and in general, SRG 74 can be provided as a one-dimensional or two-dimensional phase diagram with any continuous variation (e.g., a line or curve with a constant phase of any desired shape).

[0074] Figure 14 This is a decomposition diagram showing how the ridge 78 in the SRG 74 can follow different paths when no phase shift, discrete phase shift, or continuous phase shift is provided (e.g., chirping using any of the pitch and / or angle variations described herein). Figure 14 Section 160 shows the ridges and slots of an SRG that does not have any phase shift (e.g., no change or modulation in pitch or angle) across its spatial region (e.g., in the XZ plane). Figure 14 Section 162 illustrates the ridges and slots of an SRG having discrete phase shifts over its spatial region. As shown in section 162, different discrete regions 164 of the lateral region of the SRG are provided with different discrete grating pitches and / or angles (e.g., a first region 164 has a first pitch and / or angle, a second region 164 adjacent to the first region has a second pitch and / or a second angle that is discontinuous with the first pitch and / or discontinuous with the first angle, etc.). Figure 14 The top portion shows the SRG 74, which has a continuous phase shift across its spatial region. (As shown by...) Figure 14As shown in SRG 74, an SRG can be provided with continuously varying pitch and / or continuously varying angles across its lateral regions. This can be used, for example, to prevent the formation of ghosting artifacts in the image light associated with sharp boundaries between regions of different pitches or phases, while also maximizing spatial uniformity and MTF. One or more SRGs described herein can be configured with any of the chirped pitch, angle, and / or phase distributions (Figures) described herein (e.g., SRGs in one or more optical couplers described herein). If desired, the SRGs described herein can be replaced with other types of gratings, such as meta-gratings or volume holograms (e.g., where the constant refractive index lines of the volume hologram replace the constant modulation thickness lines of the SRG, and provide one of the continuously varying pitches and / or one of the phase maps described herein).

[0075] Physical environment: The physical environment refers to the physical world that people can sense and / or interact with without the aid of electronic systems. Physical environments, such as physical parks, include physical objects such as physical trees, physical buildings, and physical people. People can directly sense and / or interact with the physical environment through senses such as sight, touch, hearing, taste, and smell.

[0076] Computer-Generated Reality: In contrast, a computer-generated reality (CGR) environment refers to a fully or partially simulated environment that people perceive and / or interact with via electronic systems. In CGR, a subset of a person's physical motion, or a representation thereof, is tracked, and in response, one or more properties of one or more virtual objects simulated in the CGR environment are adjusted in a manner consistent with at least one physical law. For example, a CGR system can detect a person's head rotation and, in response, adjust the graphical content and sound field presented to the person in a manner similar to how such views and sounds change in a physical environment. In some cases (e.g., for accessibility reasons), the adjustment of the properties of virtual objects in the CGR environment can be done in response to a representation of physical motion (e.g., a voice command). A person can use any of their senses to sense and / or interact with CGR objects, including vision, hearing, touch, taste, and smell. For example, a person can perceive and / or interact with audio objects that create a 3D or spatial audio environment that provides the perception of a point audio source in 3D space. For example, audio objects can enable audio transparency, which selectively introduces ambient sounds from the physical environment, with or without computer-generated audio. In some CGR environments, people can sense and / or interact solely with audio objects. Examples of CGR include virtual reality and mixed reality.

[0077] Virtual Reality: A virtual reality (VR) environment is a simulated environment designed to be entirely based on computer-generated sensory input for one or more senses. A VR environment includes multiple virtual objects that a person can sense and / or interact with. For example, trees, buildings, and computer-generated images representing human avatars are examples of virtual objects. A person can sense and / or interact with virtual objects in a VR environment through the simulation of a person's presence within the computer-generated environment and / or through the simulation of a subset of a person's physical movements within the computer-generated environment.

[0078] Mixed Reality: Compared to VR environments, which are designed to be entirely based on computer-generated sensory input, mixed reality (MR) environments are simulated environments designed to incorporate sensory input from the physical environment, or a representation thereof, in addition to computer-generated sensory input (e.g., virtual objects). On the virtual continuum, a mixed reality environment is any state between, but not limited to, a purely physical environment as one end and a virtual reality environment as the other. In some MR environments, computer-generated sensory input can respond to changes in sensory input from the physical environment. Additionally, some electronic systems used to present an MR environment can track position and / or orientation relative to the physical environment to enable virtual objects to interact with real objects (i.e., physical objects or representations thereof from the physical environment). For example, a system could cause movement so that virtual trees appear stationary relative to the physical ground. Examples of mixed reality include augmented reality and augmented virtual reality. Augmented Reality: An augmented reality (AR) environment is a simulated environment in which one or more virtual objects are superimposed on a physical environment or a representation thereof. For example, electronic systems used to present an AR environment may have a transparent or semi-transparent display through which a person can directly view the physical environment. The system can be configured to present virtual objects on a transparent or semi-transparent display, allowing a person to perceive virtual objects superimposed on the physical environment. Alternatively, the system can have an opaque display and one or more imaging sensors that capture images or videos of the physical environment, which are representations of the physical environment. The system combines the images or videos with virtual objects and presents the combination on the opaque display. A person uses the system to indirectly view the physical environment via images or videos of the physical environment and perceives virtual objects superimposed on the physical environment. As used herein, the video of the physical environment displayed on the opaque display is referred to as “pass-through video,” meaning that the system uses one or more image sensors to capture images of the physical environment and uses those images when presenting the AR environment on the opaque display. Further alternatively, the system can have a projection system that projects virtual objects onto the physical environment, such as as holograms or on a physical surface, allowing a person to perceive virtual objects superimposed on the physical environment. Augmented reality environments also refer to simulated environments in which the representation of the physical environment is transformed by computer-generated sensory information. For example, in providing pass-through video, the system can transform one or more sensor images to apply a selected viewpoint (e.g., viewpoint) different from the viewpoint captured by the imaging sensor. As another example, a representation of the physical environment can be transformed by graphically modifying (e.g., zooming in) portions of it, such that the modified portions are representative but not true versions of the original captured image. Yet another example is that a representation of the physical environment can be transformed by graphically removing or blurring portions of it.Augmented Virtual: An augmented virtual (AV) environment is a simulated environment in which a virtual or computer-generated environment combines one or more sensory inputs from a physical environment. Sensory input can be a representation of one or more characteristics of the physical environment. For example, an AV park could have virtual trees and virtual buildings, but a person's face could be realistically reproduced from an image taken of a physical person. Similarly, virtual objects could adopt the shape or color of a physical object imaged by one or more imaging sensors. Furthermore, virtual objects could adopt shadows that correspond to the sun's position in the physical environment.

[0079] Hardware: Many different types of electronic systems enable humans to perceive and / or interact with various CGR environments. Examples include head-mounted systems, projection-based systems, head-up displays (HUDs), vehicle windshields with integrated display capabilities, windows with integrated display capabilities, displays shaped as lenses designed to be placed on a person's eyes (e.g., similar to contact lenses), headphones / earpieces, speaker arrays, input systems (e.g., wearable or handheld controllers with or without haptic feedback), smartphones, tablets, and desktop / laptop computers. Head-mounted systems may have one or more speakers and an integrated opaque display. Alternatively, head-mounted systems may be configured to receive an external opaque display (e.g., a smartphone). Head-mounted systems may incorporate one or more imaging sensors for capturing images or video of the physical environment, and / or one or more microphones for capturing audio of the physical environment. Head-mounted systems may have transparent or semi-transparent displays instead of opaque displays. Transparent or semi-transparent displays may have a medium through which light representing the image is directed to the person's eyes. The display may utilize digital light projection, OLED, LED, µLED, liquid crystal on silicon, laser scanning light source, or any combination of these technologies. The medium may be an optical waveguide, holographic medium, optical combiner, optical reflector, or any combination thereof. In one embodiment, a transparent or translucent display may be configured to selectively become opaque. Projection-based systems may employ retinal projection techniques that project graphic images onto the human retina. Projection systems may also be configured to project virtual objects onto a physical environment, such as as holograms or on a physical surface.

[0080] As used herein, the term "concurrent" means at least partially overlapping in time. In other words, the first and second events are referred to herein as "concurrent" if at least some of the first events occur simultaneously with at least some of the second events (e.g., if at least some of the first events occur during, concurrently with, or when at least some of the second events occur). The first and second events can be concurrent if they are synchronized (e.g., if the entire duration of the first event overlaps with the entire duration of the second event in time), but they can also be concurrent if they are asynchronous (e.g., if the first event begins before or after the second event, ends before or after the second event, or if they do not partially overlap in time). As used herein, the term "at the time of" is synonymous with "concurrent."

[0081] System 10 may collect and / or use personally identifiable information. It is well known that the use of personally identifiable information should comply with privacy policies and measures generally recognized as meeting or exceeding industry or governmental requirements for protecting user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of authorized use should be clearly explained to the user.

[0082] Physical environment: The physical environment refers to the physical world that people can sense and / or interact with without the aid of electronic systems. Physical environments, such as physical parks, include physical objects such as physical trees, physical buildings, and physical people. People can directly sense and / or interact with the physical environment through senses such as sight, touch, hearing, taste, and smell.

[0083] Computer-Generated Reality: In contrast, a computer-generated reality (CGR) environment refers to a fully or partially simulated environment that people perceive and / or interact with via electronic systems. In CGR, a subset of a person's physical motion, or a representation thereof, is tracked, and in response, one or more properties of one or more virtual objects simulated in the CGR environment are adjusted in a manner consistent with at least one physical law. For example, a CGR system can detect a person's head rotation and, in response, adjust the graphical content and sound field presented to the person in a manner similar to how such views and sounds change in a physical environment. In some cases (e.g., for accessibility reasons), the adjustment of the properties of virtual objects in the CGR environment can be done in response to a representation of physical motion (e.g., a voice command). A person can use any of their senses to sense and / or interact with CGR objects, including vision, hearing, touch, taste, and smell. For example, a person can perceive and / or interact with audio objects that create a 3D or spatial audio environment that provides the perception of a point audio source in 3D space. For example, audio objects can enable audio transparency, which selectively introduces ambient sounds from the physical environment, with or without computer-generated audio. In some CGR environments, people can sense and / or interact solely with audio objects. Examples of CGR include virtual reality and mixed reality.

[0084] Virtual Reality: A virtual reality (VR) environment is a simulated environment designed to be entirely based on computer-generated sensory input for one or more senses. A VR environment includes multiple virtual objects that a person can sense and / or interact with. For example, trees, buildings, and computer-generated images representing human avatars are examples of virtual objects. A person can sense and / or interact with virtual objects in a VR environment through the simulation of a person's presence within the computer-generated environment and / or through the simulation of a subset of a person's physical movements within the computer-generated environment.

[0085] Mixed Reality: Compared to VR environments, which are designed to be entirely based on computer-generated sensory input, mixed reality (MR) environments are simulated environments designed to incorporate sensory input from the physical environment, or a representation thereof, in addition to computer-generated sensory input (e.g., virtual objects). On the virtual continuum, a mixed reality environment is any state between, but not limited to, a purely physical environment as one end and a virtual reality environment as the other. In some MR environments, computer-generated sensory input can respond to changes in sensory input from the physical environment. Additionally, some electronic systems used to present an MR environment can track position and / or orientation relative to the physical environment to enable virtual objects to interact with real objects (i.e., physical objects or representations thereof from the physical environment). For example, a system could cause movement so that virtual trees appear stationary relative to the physical ground. Examples of mixed reality include augmented reality and augmented virtual reality. Augmented Reality: An augmented reality (AR) environment is a simulated environment in which one or more virtual objects are superimposed on a physical environment or a representation thereof. For example, electronic systems used to present an AR environment may have a transparent or semi-transparent display through which a person can directly view the physical environment. The system can be configured to present virtual objects on a transparent or semi-transparent display, allowing a person to perceive virtual objects superimposed on the physical environment. Alternatively, the system can have an opaque display and one or more imaging sensors that capture images or videos of the physical environment, which are representations of the physical environment. The system combines the images or videos with virtual objects and presents the combination on the opaque display. A person uses the system to indirectly view the physical environment via images or videos of the physical environment and perceives virtual objects superimposed on the physical environment. As used herein, the video of the physical environment displayed on the opaque display is referred to as “pass-through video,” meaning that the system uses one or more image sensors to capture images of the physical environment and uses those images when presenting the AR environment on the opaque display. Further alternatively, the system can have a projection system that projects virtual objects onto the physical environment, such as as holograms or on a physical surface, allowing a person to perceive virtual objects superimposed on the physical environment. Augmented reality environments also refer to simulated environments in which the representation of the physical environment is transformed by computer-generated sensory information. For example, in providing pass-through video, the system can transform one or more sensor images to apply a selected viewpoint (e.g., viewpoint) different from the viewpoint captured by the imaging sensor. As another example, a representation of the physical environment can be transformed by graphically modifying (e.g., zooming in) portions of it, such that the modified portions are representative but not true versions of the original captured image. Yet another example is that a representation of the physical environment can be transformed by graphically removing or blurring portions of it.Augmented Virtual: An augmented virtual (AV) environment is a simulated environment in which a virtual or computer-generated environment combines one or more sensory inputs from a physical environment. Sensory input can be a representation of one or more characteristics of the physical environment. For example, an AV park could have virtual trees and virtual buildings, but a person's face could be realistically reproduced from an image taken of a physical person. Similarly, virtual objects could adopt the shape or color of a physical object imaged by one or more imaging sensors. Furthermore, virtual objects could adopt shadows that correspond to the sun's position in the physical environment.

[0086] Hardware: Many different types of electronic systems enable humans to perceive and / or interact with various CGR environments. Examples include head-mounted systems, projection-based systems, head-up displays (HUDs), vehicle windshields with integrated display capabilities, windows with integrated display capabilities, displays shaped as lenses designed to be placed on a person's eyes (e.g., similar to contact lenses), headphones / earpieces, speaker arrays, input systems (e.g., wearable or handheld controllers with or without haptic feedback), smartphones, tablets, and desktop / laptop computers. Head-mounted systems may have one or more speakers and an integrated opaque display. Alternatively, head-mounted systems may be configured to receive an external opaque display (e.g., a smartphone). Head-mounted systems may incorporate one or more imaging sensors for capturing images or video of the physical environment, and / or one or more microphones for capturing audio of the physical environment. Head-mounted systems may have transparent or semi-transparent displays instead of opaque displays. Transparent or semi-transparent displays may have a medium through which light representing the image is directed to the person's eyes. The display may utilize digital light projection, OLED, LED, µLED, liquid crystal on silicon, laser scanning light source, or any combination of these technologies. The medium may be an optical waveguide, holographic medium, optical combiner, optical reflector, or any combination thereof. In one embodiment, a transparent or translucent display may be configured to selectively become opaque. Projection-based systems may employ retinal projection techniques that project graphic images onto the human retina. Projection systems may also be configured to project virtual objects onto a physical environment, such as as holograms or on a physical surface.

[0087] According to one embodiment, an electronic device is provided, comprising a waveguide configured to propagate light and an optical coupler configured to redirect and replicate light, the optical coupler including a substrate on the waveguide and a surface undulation grating (SRG) in the substrate, the SRG having a ridge having a pitch that varies continuously as a function of a position along an axis orthogonal to the ridge.

[0088] According to another implementation, the pitch varies periodically as a function of the position along the axis.

[0089] According to another implementation, the pitch varies sinusoidally as a function of position along the axis.

[0090] According to another implementation, the ridge follows a periodic path.

[0091] According to another implementation, the periodic path includes a sinusoidal path.

[0092] According to another implementation, the pitch varies parabolically as a function of position along the axis.

[0093] According to another implementation, the SRG has a length along the axis, and the SRG has a minimum pitch along the length at the middle.

[0094] According to another implementation, the SRG has a length along the axis, and the SRG has a minimum pitch offset from the middle along the length.

[0095] According to another embodiment, the electronic device includes an additional SRG in the substrate and overlapping with the SRG, the additional SRG having additional ridges that are not parallel to the ridges in the SRG, and the additional ridges having additional pitches that vary continuously as a function of position along additional axes orthogonal to the additional ridges.

[0096] According to another embodiment, the waveguide has a first side surface, a second side surface opposite to the first side surface, and a substrate is stacked on the first side surface. The electronic device includes an additional substrate stacked on the second side surface and an additional SRG in the additional substrate and overlapping with the SRG, the additional SRG having an additional ridge oriented non-parallel to the ridge in the SRG, and the additional ridge having an additional pitch that varies continuously as a function of a position along an additional axis orthogonal to the additional ridge.

[0097] According to another embodiment, the electronic device includes: an input coupler configured to couple light into a waveguide; and an output coupler configured to couple light out of the waveguide, the optical coupler including a cross coupler configured to redirect light from the input coupler toward the output coupler.

[0098] According to one embodiment, an electronic device is provided, comprising a waveguide configured to propagate light and an optical coupler configured to redirect and reproduce light, the optical coupler including a substrate on the waveguide and a diffraction grating in the substrate, the diffraction grating being configured to impart phase to the light upon diffraction, and the phase varying continuously as a function of position along an axis.

[0099] According to another implementation, the function is a continuous and differentiable function.

[0100] According to another implementation, the continuous and differentiable function is the sine function.

[0101] According to another implementation, the continuous and differentiable function is a parabolic function.

[0102] According to another implementation, a continuous and differentiable function is a linear function.

[0103] According to another implementation, the phase changes continuously as a function of the position along an additional axis orthogonal to the axis.

[0104] According to another implementation, the phase varies parabolically along the axis and also parabolically along an additional axis.

[0105] According to another embodiment, the diffraction grating includes a surface undulation grating.

[0106] According to one embodiment, an electronic device is provided, comprising a waveguide configured to propagate light and an optical coupler configured to redirect and replicate light, the optical coupler including a substrate on the waveguide and a surface undulation grating (SRG) in the substrate, the SRG having ridges and slots following a sinusoidal path.

[0107] The foregoing is merely illustrative and various modifications can be made to the described implementation scheme. The foregoing implementation scheme can be implemented individually or in any combination.

Claims

1. An electronic device, the electronic device comprising: Waveguide, which is configured to propagate light; as well as An optical coupler configured to redirect and reproduce the light, wherein the optical coupler includes Substrate, said substrate on the waveguide, and A surface undulation grating (SRG) is provided in the substrate, wherein the SRG has a ridge having a pitch that varies continuously as a function of the position along an axis orthogonal to the ridge.

2. The electronic device of claim 1, wherein the pitch varies periodically as a function of position along the axis.

3. The electronic device of claim 2, wherein the pitch varies sinusoidally as a function of position along the axis.

4. The electronic device of claim 3, wherein the ridge follows a periodic path.

5. The electronic device of claim 4, wherein the periodic path comprises a sinusoidal path.

6. The electronic device of claim 1, wherein the pitch varies parabolically as a function of position along the axis.

7. The electronic device of claim 6, wherein the SRG has a length along the axis and the SRG has a minimum pitch along the length at the middle.

8. The electronic device of claim 6, wherein the SRG has a length along the axis and the SRG has a minimum pitch offset from the center along the length.

9. The electronic device according to claim 1, further comprising: An additional SRG is provided in the substrate and overlaps with the SRG, wherein the additional SRG has an additional ridge that is not parallel to the ridge in the SRG, and wherein the additional ridge has an additional pitch that varies continuously as a function of a position along an additional axis orthogonal to the additional ridge.

10. The electronic device of claim 1, wherein the waveguide has a first side surface, a second side surface opposite to the first side surface, and the substrate is stacked on the first side surface, the electronic device further comprising: An additional substrate, which is stacked on the second side surface; as well as An additional SRG is provided in the additional substrate and overlaps with the SRG, wherein the additional SRG has an additional ridge that is not parallel to the ridge in the SRG, and wherein the additional ridge has an additional pitch that varies continuously as a function of a position along an additional axis orthogonal to the additional ridge.

11. The electronic device according to claim 1, further comprising: An input coupler configured to couple the light to the waveguide; as well as An output coupler configured to couple light out of the waveguide, the optical coupler including a cross coupler configured to redirect light from the input coupler toward the output coupler.

12. An electronic device, the electronic device comprising: Waveguide, which is configured to propagate light; as well as An optical coupler configured to redirect and reproduce the light, wherein the optical coupler includes Substrate, said substrate on the waveguide, and A diffraction grating in the substrate, wherein the diffraction grating is configured to impart phase to the light when diffracting the light, and wherein the phase varies continuously as a function of position along an axis.

13. The electronic device of claim 12, wherein the function is a continuous and differentiable function.

14. The electronic device of claim 13, wherein the continuous and differentiable function is a sine function.

15. The electronic device of claim 13, wherein the continuous and differentiable function is a parabolic function.

16. The electronic device of claim 12, wherein the continuous and differentiable function is a linear function.

17. The electronic device of claim 12, wherein the phase varies continuously as a function of the position along an additional axis orthogonal to the axis.

18. The electronic device of claim 17, wherein the phase varies parabolically along the axis and parabolically along the additional axis.

19. The electronic device of claim 12, wherein the diffraction grating comprises a surface undulation grating.

20. An electronic device, the electronic device comprising: Waveguide, which is configured to propagate light; as well as An optical coupler configured to redirect and reproduce the light, wherein the optical coupler includes Substrate, said substrate on the waveguide, and A surface undulation grating (SRG) is provided in the substrate, wherein the SRG has ridges and grooves following a sinusoidal path.

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