Optical system with edge-coupled dielectric layer

Abstract

A display can include a waveguide that directs light toward an eyebox. The waveguide can include a first dielectric layer and a second dielectric layer that are edge-coupled at an interface. The first dielectric layer can include louver mirror cross-couplers that redirect the light toward the second dielectric layer. The second dielectric layer can include a volume hologram output coupler that couples the light out of the waveguide. Additional layers can be interposed between the first dielectric layer and a waveguide substrate. These additional layers can help confine the light within the first dielectric layer as the light propagates, so that all of the light enters the second dielectric layer through the interface. This can configure the waveguide to occupy a minimal amount of space within the display, while also providing the eyebox with as bright and uniform an image as possible.

Description

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 055,791, filed July 23, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0002] This disclosure relates in general to optical systems, and more specifically to optical systems for displays.

[0003] Electronic devices may include displays that present images close to the user's eyes. For example, devices such as virtual reality and augmented reality headsets may include displays with optical elements that allow the user to view the display.

[0004] Designing devices like these can be challenging. If not handled carefully, the components used to display content can be unsightly and bulky, and may not exhibit the expected level of optical performance. Summary of the Invention

[0005] Electronic devices such as head-mounted displays may have one or more near-eye displays that generate images for the user. A head-mounted display may be a pair of virtual reality glasses or an augmented reality headset, which allows an observer to view both computer-generated images and real-world objects in the observer's surrounding environment.

[0006] The display may include a display module that generates image light to be provided to the trocar. An optical waveguide directs the image light from the display module toward the trocar. The optical waveguide may include a first waveguide substrate and a second waveguide substrate. A first dielectric layer and a second dielectric layer may be interposed between the first waveguide substrate and the second waveguide substrate. The second dielectric layer may be coupled to the edge of the first dielectric layer at an interface. An input coupler, such as an input coupling prism, may couple the image light into the first dielectric layer through the first waveguide substrate. The first dielectric layer may propagate the image light via total internal reflection.

[0007] As image light propagates through the first dielectric layer, a cross-coupler in the first dielectric layer redirects the image light toward the second dielectric layer. The first layer may be interposed between the first waveguide substrate and the first dielectric layer. The second layer may be interposed between the second waveguide substrate and the first dielectric layer. Both the first and second layers can be dielectric layers, such as optically transparent adhesive layers. The first and second layers may have a different refractive index than the first dielectric layer. In another suitable arrangement, the first and second layers may be reflective coatings. As image light propagates along the first dielectric layer, the first and second layers can be used to confine the image light within the first dielectric layer, such that all image light enters the second dielectric layer through the interface between the first and second dielectric layers. An output coupler in the second dielectric layer couples the image light out of the waveguide and toward the peephole. The cross-coupler may include a louvered mirror embedded in the first dielectric layer. The output coupler may include a volumetric hologram recorded in the second dielectric layer. When configured in this way, the waveguide occupies a minimal amount of space within the display while providing the peephole with the brightest and most uniform image possible. Attached Figure Description

[0008] Figure 1 These are illustrations of exemplary systems with displays based on some implementation schemes.

[0009] Figure 2 This is a top view of an exemplary optical system for a display with a waveguide, according to some embodiments, the waveguide having an input coupler, a cross coupler, and an output coupler.

[0010] Figure 3 This is a top view of an exemplary waveguide with a louvered mirror cross coupler and a holographic output coupler according to some implementation schemes.

[0011] Figure 4 This is a bottom view illustrating how exemplary louvered mirror cross couplers and holographic output couplers can be formed in different stacked media layers according to some embodiments.

[0012] Figure 5 This is a bottom view of an exemplary waveguide according to some implementation schemes, having a louvered mirror cross coupler and a holographic output coupler formed in the corresponding edge coupling medium layer.

[0013] Figure 6 This is a bottom view of an exemplary waveguide according to some embodiments, the exemplary waveguide having a louvered mirror cross coupler formed in a first dielectric layer, a holographic output coupler formed in a second dielectric layer coupled to the edge of the first dielectric layer, and an optically transparent adhesive for reducing light loss at the interface between the first and second dielectric layers. Detailed Implementation

[0014] Figure 1 An exemplary system is illustrated, having a device with one or more near-eye display systems. System 10 may be a head-mounted device having one or more displays, such as a near-eye display 14 mounted within a support structure (housing) 20. The support structure 20 may be shaped like a pair of glasses (e.g., a support frame), may be formed with a helmet-shaped housing, or may have other configurations for assisting in mounting and securing components of the near-eye display 14 to the user's head or near their eyes. The near-eye display 14 may include one or more display modules, such as display module 14A, and one or more optical systems, such as optical system 14B. Display module 14A may be mounted in the support structure, such as support structure 20. Each display module 14A may emit light 22 (image light), which is redirected towards the user's eye at a trocar 24 using an associated one of the optical systems 14B.

[0015] 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 (instructions) 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.).

[0016] 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 devices (e.g., tethered computers, portable devices such as handheld devices or laptops) or other electrical devices, 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 devices. 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 devices, etc.). In a suitable arrangement sometimes described herein as an example, component 18 may include a gaze tracking sensor that collects gaze image data from the user's eyes at peephole 24 to track the direction of the user's gaze in real time.

[0017] Display module 14A may include a reflective display (e.g., a liquid crystal on silicon (LCOS) display, a digital micromirror device (DMD) display, or other spatial light modulator), an emissive display (e.g., a micro light-emitting diode (uLED) display, an organic light-emitting diode (OLED) display, a laser-based display, etc.), or other types of displays. The light source in display module 14A may include uLED, OLED, LED, laser, a combination of these devices, or any other desired light-emitting component.

[0018] Optical system 14B can form lenses that allow an observer (see, for example, the observer's eye at peephole 24) to view an image on display 14. Two optical systems 14B may be associated with the user's respective left and right eyes (e.g., for forming a left lens and a right lens). A single display 14 can generate images for both eyes, or a pair of displays 14 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 components in optical system 14B 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).

[0019] If desired, the optical system 14B may include components (e.g., an optical combiner, etc.) to allow optical combination of real-world image light from a real-world image or object 25 with virtual (computer-generated) images, such as virtual images in image light 22. In this type of system (sometimes called an augmented reality system), the user of system 10 can view both real-world content and computer-generated content overlaid on top of the real-world content. Camera-based augmented reality systems may also be used in device 10 (e.g., an arrangement where a camera captures a real-world image of object 25 and digitally merges that content with virtual content at optical system 14B).

[0020] 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 provides image content to display 14). During operation, control circuitry 16 may provide image content to display 14. 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 14 by control circuitry 16 may be viewed by an observer at peephole 24.

[0021] Figure 2 It is possible Figure 1 A top view of the exemplary display 14 used in system 10. (See figure) Figure 2 As shown, the near-eye display 14 may include one or more display modules such as display module 14A, and an optical system such as optical system 14B. Optical system 14B may include optical elements such as one or more waveguides 26. Waveguide 26 may include one or more laminated substrates (e.g., laminated planes and / or curved layers, sometimes referred to herein as "waveguide substrates") formed of optically transparent materials such as plastics, polymers, glass, etc.

[0022] If desired, waveguide 26 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") 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 produce 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 an electric field applied to the holographic recording medium. If desired, multiple holographic phase gratings (holograms) may be recorded within a holographic medium of the same volume (e.g., superimposed within a grating medium of the same volume). The holographic phase grating may be, for example, a volumetric 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.

[0023] The diffraction grating on waveguide 26 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 26 may also include surface undulation gratings formed on one or more surfaces of a substrate in waveguide 26, 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 medium 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) or overlapping gratings formed in corresponding layers of the grating medium. If desired, a venetian blind mirror (also referred to as a “venetian-style” mirror), such as a venetian partially reflective (e.g., metallic) coating, may be formed in the grating medium for redirecting image light 22 (e.g., as part of cross-coupler 32 and / or output coupler 30).

[0024] Optical system 14B may include collimating optics, such as imaging optics 34. Imaging optics 34 (sometimes referred to herein as imaging lens 34) may include one or more lens elements that help orient image light 22 toward waveguide 26. If desired, display module 14A may be mounted on... Figure 1 The optical system 14B can be mounted within the support structure 20, and may be mounted between portions of the support structure 20 (e.g., to form a lens aligned with the trocar box 24). Other mounting arrangements may be used if desired.

[0025] like Figure 2As shown, display module 14A can generate image light 22 associated with the image content to be displayed on trocar 24. The image light 22 can be collimated using lenses such as those in imaging optics 34. Optical system 14B can be used to present the image light 22 output from display module 14A onto trocar 24.

[0026] The optical system 14B may include one or more optical couplers such as an input coupler 28, a cross coupler 32, and an output coupler 30. Figure 2 In the example, input coupler 28, cross coupler 32, and output coupler 30 are formed at or on waveguide 26. Input coupler 28, cross coupler 32, and / or output coupler 30 may be completely embedded in the substrate of waveguide 26, partially embedded in the substrate of waveguide 26, or mounted to waveguide 26 (e.g., mounted to the outer surface of waveguide 26), etc.

[0027] Figure 2 The examples provided are merely illustrative. One or more of these couplers (e.g., cross coupler 32) may be omitted. Optical system 14B 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 from couplers 28, 32, and 30. Waveguide 26 may be at least partially bent or folded if desired.

[0028] Waveguide 26 can guide image light 22 downward along its length via total internal reflection. Input coupler 28 can be configured to couple image light 22 from display module 14A (imaging optics 34) into waveguide 26, while output coupler 30 can be configured to couple image light 22 from inside waveguide 26 to outside waveguide 26 and toward peephole 24. For example, display module 14A can emit image light 22 toward optical system 14B along the +Y direction. When image light 22 strikes input coupler 28, input coupler 28 can redirect image light 22 such that it propagates within waveguide 26 via total internal reflection toward output coupler 30 (e.g., along the +X direction). When image light 22 strikes output coupler 30, output coupler 30 can redirect image light 22 away from waveguide 26 toward peephole 24 (e.g., backward along the Y-axis). For example, when the cross-coupler 32 is formed at the waveguide 26, the cross-coupler 32 can redirect the image light 22 in one or more directions and / or extend the image light 22 as it propagates downward along the length of the waveguide 26. If needed, the output coupler 30 can additionally or alternatively extend the image light.

[0029] The input coupler 28, cross coupler 32, and / or output coupler 30 may be based on reflective optics, refractive optics, and / or diffractive (e.g., holographic) optics. In an arrangement where couplers 28, 30, and 32 are formed from reflective and refractive optics, they may include one or more reflectors (e.g., louvered mirrors; arrays of micromirrors, partial mirrors, or other reflectors). In an arrangement where couplers 28, 30, and 32 are based on diffractive optics, they may include diffraction gratings (e.g., volume holograms, surface undulation gratings, etc.). In other words, any combination of diffractive, reflective, and / or refractive optics can be used to form the input coupler 28, cross coupler 32, and output coupler 30. As an example, the cross coupler 32 may be formed from a surface undulation grating, while the output coupler 30 may be formed from a louvered mirror or a volume hologram. As another example, the input coupler 28 may include a prism mounted to the surface of the waveguide 26, the cross coupler 32 may include a louvered mirror embedded in a first dielectric layer of the waveguide 26, and the output coupler 30 may include a diffraction grating structure, such as a volumetric hologram recorded in a second dielectric layer of the waveguide 26 (e.g., a holographic recording dielectric layer).

[0030] Figure 3 This is a front view of waveguide 26, showing how input coupler 28 may include a prism mounted to the surface of waveguide 26, cross coupler 32 may include a louvered mirror, and output coupler 30 may include a diffraction grating structure such as a volume hologram. Figure 3 As shown, the input coupler 28 may include an input coupling prism, such as input coupling prism 50. Input coupling prism 50 may be mounted to a side surface of waveguide 26.

[0031] Image light 22 can follow from display module 14A to peephole 24 ( Figure 2 The optical path is as follows: Input coupler 28, cross coupler 32, and output coupler 30 can be inserted into this optical path. Cross coupler 32 can be inserted into the optical path between input coupler 28 and output coupler 30. Output coupler 30 can be inserted into the optical path between cross coupler 32 and the trocar box.

[0032] The input coupling prism 50 can receive image light 22 (e.g., along its own path). Figure 2(The display module 14A in the +Y direction). The input coupling prism 50 can be a reflective input coupling prism or a transmissive input coupling prism. An example of an input coupling prism 50 being a transmissive input coupling prism is described herein by way of example. The input coupling prism 50 can couple the image light 22 into the waveguide 26 by redirecting the image light 22 along a first direction (e.g., downward into the waveguide 26 along the +Y direction and along the -Z direction). The input coupling prism 50 can couple the image light 22 into the waveguide 26 at an angle such that the image light propagates along the waveguide 26 (e.g., along the -Z direction) via total internal reflection.

[0033] like Figure 3 As shown, the cross-coupler 32 may include a venetian blind, such as a venetian blind 42 embedded in a first dielectric layer of waveguide 26. The venetian blind 42 (sometimes referred to herein as a partially reflective venetian blind 42) may be formed from a partially reflective coating embedded in the first dielectric layer. The venetian blind 42 may redirect (reflect) the image light 22 coupled to the waveguide 26 in a second direction toward the output coupler 30 (e.g., along the +X direction). After being reflected by the venetian blind 42, the image light 22 may continue to propagate to the output coupler 30 via total internal reflection.

[0034] Venetian blind mirror 42 may, for example, have a relative Figure 3 The mirror plane is oriented at a non-parallel angle to both the X and Z axes. The reflection axis of the venetian blind mirror 42 is oriented perpendicular to the mirror plane. Image light can be incident on the venetian blind mirror 42 at an incident angle and reflected away from the venetian blind mirror 42 at a reflection angle. The reflection axis can bisect the incident angle and the reflection angle. The reflection axis can lie in the XZ plane, or, if desired, can also be oriented at a non-zero angle relative to the XZ plane. In other words, as... Figure 3 As shown, in addition to being oriented at a non-zero angle relative to the X and Z axes, the reflection axis can also be oriented out of plane (e.g., it can have positive or negative non-zero out-of-plane components relative to the XZ plane).

[0035] Output coupler 30 couples image light 22 from cross coupler 32 out of waveguide 26 by redirecting the image light back to the eyebox in the direction of arrow 40 (e.g., along the -Y direction). Output coupler 30 may include, for example, a diffraction grating structure recorded in a second dielectric layer. This diffraction grating structure may include multiple volumetric holograms. For example, the reflection axis of the volumetric hologram may be oriented at a non-zero angle relative to the normal and side surfaces of waveguide 26 and / or at a non-zero angle relative to the X and Z axes. Similarly, lines of constant refractive index of the hologram (e.g., fringes of the hologram) may be oriented at a non-zero angle relative to the X and Z axes. The volumetric hologram may include multiple (overlapping) holograms superimposed in the same volume of the second dielectric layer and / or may include multiple holograms that are at least partially non-overlapping. Multiplexing multiple holograms allows the diffraction grating structure to diffract image light 22 across a range of incident angles and wavelengths.

[0036] Figure 4 This is a bottom view of waveguide 26 in an example where the first and second dielectric layers are stacked on top of each other (e.g., along...). Figure 3 (The direction of arrow 44 is cut off). For example... Figure 4 As shown, waveguide 26 may include a first waveguide portion 26A stacked vertically relative to the second waveguide portion 26B. In other words, the second waveguide portion 26B can be inserted between the first waveguide portion 26A and the display module 14A. Figure 2 ).

[0037] The first waveguide portion 26A may include a first dielectric layer (e.g., first dielectric layer 62), a first waveguide substrate 64, and a second waveguide substrate 60. The first dielectric layer 62 may be inserted (clamped) between the first waveguide substrate 64 and the second waveguide substrate 60. The second waveguide portion 26B may include a second dielectric layer (e.g., second dielectric layer 56), a third waveguide substrate 58 mounted to the second waveguide substrate 60, and a fourth waveguide substrate 54. The second dielectric layer 56 may be inserted (clamped) between the third waveguide substrate 58 and the fourth waveguide substrate 54. Cross-coupler 32 (e.g., Figure 3 The venetian blind mirror 42 may be embedded within some or all of the first dielectric layer 62. The output coupler 30 (e.g., a diffraction grating structure such as a volume hologram) may be recorded across some or all of the second dielectric layer 56. Figure 4 In the example, the output coupler 30 is non-overlapping with respect to the cross coupler 32. The input coupling prism 50 can be mounted to the fourth waveguide substrate 54.

[0038] like Figure 4 As shown, the input coupling prism 50 couples the image light 22 into the waveguide 26. The image light 22 can reach the cross coupler 32 through the second waveguide section 26B. The cross coupler 32 contains a venetian blind (e.g., Figure 3The venetian blind 42) redirects the image light 22, causing it to propagate via total internal reflection in the +X direction through waveguide portions 26A and 26B. When the image light hits the output coupler 30, the output coupler 30 couples the image light out of the second waveguide portion 26B and toward the peephole (e.g., in the -Y direction), as indicated by arrow 40. This configuration of the waveguide 26 with stacked waveguide portions 26A and 26B allows the image light to propagate without ray angular errors. However, this configuration of the waveguide 26 can result in a relatively large thickness 52, causing the waveguide to consume excessive volume and weight within the system 10. Furthermore, Figure 4 Waveguide 26 can exhibit relatively low optical uniformity and throughput.

[0039] To mitigate these problems, the first and second dielectric layers can be edge-coupled within waveguide 26. Figure 5 This is a bottom view of waveguide 26 in an example where the first and second dielectric layers are coupled at the inner edge of waveguide 26. (See example...) Figure 5 As shown, waveguide 26 may include a first waveguide substrate 72 and a second waveguide substrate 91. Waveguide substrate 72 can be inserted between waveguide substrate 91 and display module 14A. Figure 2 Waveguide 26 may further include a first dielectric layer (e.g., first dielectric layer 88) and a second dielectric layer (e.g., second dielectric layer 90). The first dielectric layer 88 may be a holographic recording medium or any other desired dielectric (e.g., plastic, glass, polymer, etc.). The second dielectric layer 90 may be a holographic recording medium. Cross-coupler 32 (e.g., Figure 3 The louvered mirror 42 can be embedded within the first dielectric layer 88. The output coupler 30 (e.g., a diffraction grating structure such as a volume hologram) can be recorded in the second dielectric layer 90.

[0040] The first waveguide substrate 72 may have a first side surface 74 and an opposing second side surface 78. Side surface 74 may form the outer side surface of waveguide 26. Similarly, the second waveguide substrate 91 may have a first side surface 80 and an opposing second side surface 82. Side surface 82 may form the outer side surface of waveguide 26. Side surfaces 74, 78, 80 and / or 82 may be planar (e.g., Figure 5(As shown) or may be fully or partially curved. The first dielectric layer 88 may have a first side surface 84 at the first waveguide substrate 72 and an opposing second side surface 86 at the second waveguide substrate 91. The second dielectric layer 90 may have a first side surface 76 at the first waveguide substrate 72 and an opposing second side surface 79 at the second waveguide substrate 91. The first waveguide substrate 72 may be stacked (e.g., side surfaces 78 may be in direct contact) onto the side surfaces 84 of the first dielectric layer 88 and the side surfaces 76 of the second dielectric layer 90. The second waveguide substrate 91 may be stacked (e.g., side surfaces 80 may be in direct contact) onto the side surfaces 86 of the first dielectric layer 88 and the side surfaces 79 of the second dielectric layer 90. The first dielectric layer 88 may have a peripheral edge coupling the edge of the side surface 84 to the edge of the side surface 86. Similarly, the second dielectric layer 90 may have a peripheral edge coupling the edge of the side surface 76 to the edge of the side surface 79.

[0041] The first dielectric layer 88 can be edge-coupled (e.g., butt-coupled) to the second dielectric layer 90 at interface 92, rather than being vertically stacked (e.g., as shown in the image). Figure 4 As shown, the first dielectric layer 88 can be coupled (e.g., in direct contact) to the second dielectric layer at the interface 92 (sometimes referred to herein as joint 92, edge-coupled interface 92, edge-coupled joint 92, or butt-coupled joint 92).

[0042] The peripheral edge of the second dielectric layer 90. In this way, the side surface 84 of the first dielectric layer 88 may be coplanar with the side surface 76 of the second dielectric layer 90, and the side surface 86 of the first dielectric layer 88 may be coplanar with the side surface 79 of the second dielectric layer 90. Arranging the first and second dielectric layers in this way allows the waveguide 26 to be configured to exhibit substantially less than (e.g., at least 50% smaller) the size of the second dielectric layer. Figure 4 The thickness is 52 and the thickness is 70.

[0043] like Figure 5 As shown, the input coupling prism 50 couples image light 22 into the first dielectric layer 88. The cross-coupler 32 in the first dielectric layer 88 (e.g., Figure 3The venetian blind 42 can redirect the image light 22 toward the output coupler 30 (e.g., along the +X direction). The image light 22 reflected by the cross coupler 32 can propagate downward along the waveguide 26 via total internal reflection. During propagation through the first dielectric layer 88, the image light 22 can be reflected between the side surface 74 of the waveguide substrate 72 and the side surface 82 of the waveguide substrate 91 via total internal reflection. This allows a first portion of the image light to enter the second dielectric layer 90 through the interface 92, as indicated by arrow 94, while a second portion of the image light enters the second dielectric layer 90 through the waveguide substrate 72 and / or the waveguide substrate 91, as indicated by arrow 96. The output coupler 30 in the second dielectric layer 90 can couple at least some of the image light 22 out of the waveguide 26 toward the peephole (e.g., as indicated by arrow 40).

[0044] The second dielectric layer 90 may have a different bulk refractive index than the first dielectric layer 88. This allows a portion of the image light passing through interface 92 (e.g., as shown by arrow 94) to enter the second dielectric layer 90 at a different angle than a portion of the image light entering the second dielectric layer 90 through waveguide substrates 72 and 91 (e.g., as shown by arrow 94). This angular difference in the image light entering the second dielectric layer 90 can lead to undesirable light loss and inhomogeneity in the image light reaching the trocar 24.

[0045] To mitigate these problems, waveguide 26 may be provided with a structure for confining image light 22 within the first dielectric layer 88 when image light propagates through the first dielectric layer 88 via total internal reflection. Figure 6 This is a diagram illustrating how waveguide 26 can be configured to confine image light 22 within the first dielectric layer 88 when image light propagates through the first dielectric layer 88.

[0046] like Figure 6As shown, additional layers such as optically clear adhesive layers 100 and 102 may be disposed on the first dielectric layer 88 to confine the image light 22 within the first dielectric layer 88 during propagation. Optically clear adhesive layer 100 may be interposed between a side surface 78 of the waveguide substrate 72 and a side surface 84 of the first dielectric layer 88 (e.g., optically clear adhesive layer 100 may be laminated onto and in direct contact with both side surfaces 78 and 84). If desired, optically clear adhesive layer 100 may help adhere the waveguide substrate 72 to the first dielectric layer 88. Similarly, optically clear adhesive layer 102 may be interposed between a side surface 80 of the waveguide substrate 91 and a side surface 86 of the first dielectric layer 88 (e.g., optically clear adhesive layer 102 may be in direct contact with both side surfaces 86 and 80). If desired, optically clear adhesive layer 102 may help adhere the waveguide substrate 91 to the first dielectric layer 88. The first dielectric layer 88 may be interposed between optically transparent adhesive layers 100 and 102. Optically transparent adhesive layers 100 and 102 may partially or completely overlap with the first dielectric layer 88 (e.g., up to interface 92) without extending beyond interface 92 or overlapping with the second dielectric layer 90. If desired, the second dielectric layer 90 may be formed without an optically transparent adhesive layer (e.g., side surface 76 may directly contact side surface 78 of waveguide substrate 72, and side surface 79 may directly contact side surface 79 of waveguide substrate 91, such as...). Figure 6 (As shown).

[0047] The first dielectric layer 88 may have a first refractive index n1 (e.g., bulk refractive index). The second dielectric layer 90 may have a second volumetric refractive index n2 (e.g., bulk refractive index) that is different from (e.g., less than) the first refractive index n1. The optically clear adhesive 100 may have a third refractive index n3 that is different from (e.g., less than) the first refractive index n1. The third refractive index n3 may be selected such that the difference between the first refractive index n1 and the third refractive index n3 is sufficiently large that image light 22 is reflected at the interface between the optically clear adhesive layers 100 and 102 and the first dielectric layer 88 (e.g., the absolute value of the difference between refractive indices n1 and n3 may be 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.2 or greater, 1.0 or greater, etc.). As an example, the first refractive index n1 can be 2.0, 1.8, between 1.8 and 2.2, between 1.7 and 2.5, greater than 1.7, greater than 1.8, greater than 1.9, greater than 1.6, greater than 2.0, or other values. The second refractive index n2 can be 1.5, 1.4, between 1.2 and 1.7, or any other value. The third refractive index n3 can be 1.5, 1.4, 1.6, between 1.4 and 1.6, between 1.3 and 1.7, less than 1.8, less than 1.7, less than 1.6, less than 1.5, less than 1.4, etc.

[0048] The presence of optically transparent adhesive layers 100 and 102 establishes a clear refractive index boundary between the optically transparent adhesive layers and the first dielectric layer 88 (e.g., at side surfaces 84 and 86 of the first dielectric layer 88). This may result in image light 22 being reflected from the interface (e.g., side surfaces 84 and 86) between the optically transparent adhesive layers 100 and 102 and the first dielectric layer 88, preventing it from entering the waveguide substrates 72 and 91, when image light propagates through the first dielectric layer 88 via total internal reflection. In other words, when image light 22 propagates along the first dielectric layer 88 via total internal reflection, optically transparent adhesive layer 100 blocks image light 22 from entering the waveguide substrate 72, and optically transparent adhesive layer 102 blocks image light 22 from entering the waveguide substrate 91. By confining the image light 22 within the first dielectric layer 88 as it propagates through the first dielectric layer 88 via total internal reflection, all image light can enter the second dielectric layer 90 through the interface 92, thereby mitigating any losses associated with light entering the second dielectric layer 90 via waveguide substrates 72 and 91 (e.g., as...). Figure 5 (As indicated by arrow 96). The output coupler 30 (e.g., a diffraction grating structure such as a volumetric hologram) can then diffract the image light 22 passing through interface 92 out of waveguide 26 and toward the peephole, as indicated by arrow 40. This can be used to provide the peephole with the brightest and most uniform image possible, while also allowing waveguide 26 to exhibit a relatively compact thickness 70.

[0049] Figure 6 The examples provided are merely illustrative. If desired, the optically clear adhesive layers 100 and 102 can be any other desired dielectric layer having a refractive index n3 (e.g., the optically clear adhesive layers 100 and 102 can be non-adhesive dielectric layers or dielectric coatings). In another suitable arrangement, the optically clear adhesive layers 100 and 102 can be replaced by reflective layers (e.g., metallic coatings or other coatings) that reflect the image light 22 and thus confine the image light 22 within the first dielectric layer 88 during propagation.

[0050] According to one embodiment, an optical waveguide is provided, comprising: a first waveguide substrate and a second waveguide substrate; a first dielectric layer and a second dielectric layer, the first dielectric layer and the second dielectric layer being interposed between the first waveguide substrate and the second waveguide substrate, the second dielectric layer being edge-coupled to the first dielectric layer, and the first dielectric layer being configured to propagate image light via total internal reflection; a venetian blind in the first dielectric layer and configured to redirect the image light toward the second dielectric layer; volumetric holograms in the second dielectric layer and configured to couple the image light out of the optical waveguide; a first layer interposed between the first dielectric layer and the first waveguide substrate; and a second layer interposed between the first dielectric layer and the second waveguide substrate, wherein when the image light propagates along the first dielectric layer via total internal reflection, the first layer is configured to block the image light from entering the first waveguide layer, and the second layer is configured to block the image light from entering the second waveguide layer.

[0051] According to another embodiment, the second dielectric layer is coupled to the edge of the first dielectric layer at the interface, and the image light is configured to enter the second dielectric layer from the first dielectric layer through the interface.

[0052] According to another embodiment, the image light is configured to propagate along the second dielectric layer via total internal reflection.

[0053] According to another embodiment, when the image light propagates along the second dielectric layer via total internal reflection, the image light is configured to enter the first waveguide substrate and the second waveguide substrate.

[0054] According to another implementation, the first and second layers are dielectric layers.

[0055] According to another embodiment, these dielectric layers include an optically transparent adhesive.

[0056] According to another embodiment, the first dielectric layer has a first refractive index, the second dielectric layer has a bulk refractive index different from the first refractive index, and the optically transparent adhesive has a second refractive index less than the first refractive index.

[0057] According to another embodiment, the first and second layers include a reflective coating.

[0058] According to one embodiment, a display system configured to display image light at a trocar chamber is provided. The display system includes: a first waveguide substrate and a second waveguide substrate; a first dielectric layer and a second dielectric layer, the first dielectric layer and the second dielectric layer being interposed between the first waveguide substrate and the second waveguide substrate, the second dielectric layer being edge-coupled to the first dielectric layer, and the first dielectric layer having a first refractive index; a cross-coupler in the first dielectric layer, the first dielectric layer being configured to propagate image light via total internal reflection when image light propagates through the first dielectric layer, and the cross-coupler being configured to redirect image light toward the second dielectric layer when image light propagates through the first dielectric layer; an output coupler in the second dielectric layer and configured to couple image light out of the second dielectric layer and toward the trocar chamber; a first dielectric layer interposed between the first dielectric layer and the first waveguide substrate; and a second dielectric layer interposed between the first dielectric layer and the second waveguide substrate, the first dielectric layer and the second dielectric layer having a second refractive index different from the first refractive index.

[0059] According to another embodiment, the first dielectric layer has a first side surface coupled to the first dielectric layer, the first dielectric layer has a second side surface opposite to the first side surface and coupled to the second dielectric layer, and the first side surface and the second side surface are configured to reflect image light when image light propagates through the first dielectric layer.

[0060] According to another embodiment, the second dielectric layer is coupled to the edge of the first dielectric layer at the interface, and image light enters the second dielectric layer from the first dielectric layer through the interface.

[0061] According to another embodiment, the first dielectric layer includes an optically transparent adhesive.

[0062] According to another embodiment, the second dielectric layer includes an optically transparent adhesive.

[0063] According to another embodiment, the first refractive index is greater than or equal to 1.6, and the second refractive index is less than or equal to 1.6.

[0064] According to another embodiment, the cross coupler includes a louvered mirror embedded in a first medium layer.

[0065] According to another embodiment, the output coupler includes a volumetric hologram in a second dielectric layer.

[0066] According to another embodiment, the cross coupler includes a louvered mirror embedded in a first medium layer.

[0067] According to another embodiment, the second dielectric layer has a bulk refractive index that is less than that of the first refractive index.

[0068] According to another embodiment, the display system includes an input coupling prism mounted to a first waveguide substrate and configured to couple image light into a first dielectric layer.

[0069] According to one embodiment, a display system is provided, the display system comprising: a first dielectric layer having opposing first side surfaces and second side surfaces; a second dielectric layer coupled to an edge of the first dielectric layer at an interface; a first layer having an optically transparent adhesive laminated onto the first dielectric layer; a second layer having an optically transparent adhesive laminated onto the second dielectric layer; and an input coupler configured to couple image light into the first dielectric layer, the first dielectric layer being configured to propagate the image light via total internal reflection, wherein the first layer and the second layer having the optically transparent adhesive are configured to... Image light is confined within a first dielectric layer as it propagates through the first dielectric layer via total internal reflection. The image light is configured to enter a second dielectric layer from the first dielectric layer via an interface, and the second dielectric layer is configured to propagate the image light via total internal reflection after the image light has passed through the interface. A cross-coupler is located in the first dielectric layer and is configured to redirect the image light toward the second dielectric layer as it propagates through the first dielectric layer via total internal reflection. An output coupler is located in the second dielectric layer and is configured to redirect the image light toward the trocar as it propagates through the second dielectric layer via total internal reflection.

[0070] According to another embodiment, the input coupler includes a prism, the cross coupler includes a louvered mirror embedded in a first dielectric layer, and the output layer includes a volumetric hologram recorded in a second dielectric layer.

[0071] According to another embodiment, the display system includes a first waveguide substrate and a second waveguide substrate, the first waveguide substrate being in direct contact with a first side surface having a first layer of optically transparent adhesive and a second dielectric layer; the second waveguide substrate being in direct contact with a second side surface having a second layer of optically transparent adhesive and a second dielectric layer.

[0072] According to another embodiment, the first and second layers with optically transparent adhesive have different refractive indices than the first dielectric layer.

[0073] The foregoing description is merely illustrative and various modifications can be made to the described implementation scheme. The described implementation scheme can be implemented independently or in any combination.

Claims

1. An optical waveguide, the optical waveguide comprising: First waveguide substrate and second waveguide substrate; A first dielectric layer and a second dielectric layer are interposed between a first waveguide substrate and a second waveguide substrate, wherein the second dielectric layer is edge-coupled to the first dielectric layer, and wherein the first dielectric layer is configured to propagate image light via total internal reflection. A Venetian blind, wherein the Venetian blind is in the first medium layer and is configured to redirect the image light toward the second medium layer; A volumetric hologram, wherein the volumetric hologram is located in the second dielectric layer and is configured to couple the image light out of the optical waveguide; The first layer is inserted between the first dielectric layer and the first waveguide substrate; and The second layer is inserted between the first dielectric layer and the second waveguide substrate, wherein when the image light propagates along the first dielectric layer via total internal reflection, the first layer is configured to block the image light from entering the first waveguide substrate, and the second layer is configured to block the image light from entering the second waveguide substrate.

2. The optical waveguide of claim 1, wherein the second dielectric layer is coupled to the edge of the first dielectric layer at an interface, and wherein substantially all of the image light is configured to enter the second dielectric layer from the first dielectric layer through the interface.

3. The optical waveguide of claim 2, wherein the image light is configured to propagate along the second dielectric layer via total internal reflection, and wherein when the image light propagates along the second dielectric layer via total internal reflection, the image light is configured to enter the first waveguide substrate and the second waveguide substrate.

4. The optical waveguide of claim 1, wherein the volumetric hologram in the second dielectric layer is configured to couple the image light out of the optical waveguide in one direction, wherein the first layer overlaps with the first dielectric layer in the direction, and wherein the first layer does not overlap with the second dielectric layer in the direction.

5. The optical waveguide of claim 1, wherein the first layer and the second layer are dielectric layers, comprising an optically transparent adhesive or comprising a reflective coating.

6. The optical waveguide according to claim 1, wherein the first layer is in direct contact with the first dielectric layer, and wherein the second layer is in direct contact with the first dielectric layer.

7. The optical waveguide of claim 1, wherein the first dielectric layer has a first refractive index, the second dielectric layer has a bulk refractive index different from the first refractive index, the first layer has a second refractive index less than the first refractive index, and the second refractive index is configured to block the image light from entering the first waveguide substrate when the image light propagates along the first dielectric layer via total internal reflection.

8. The optical waveguide according to claim 1, further comprising: An input coupler is located on the first waveguide substrate and configured to couple the image light into the first dielectric layer, wherein the image light coupled into the first dielectric layer is configured to propagate along the second dielectric layer via total internal reflection, and wherein the image light coupled into the first dielectric layer is configured to enter the first waveguide substrate when it propagates along the second dielectric layer via total internal reflection.

9. A display system configured to display image light at a trocar chamber, the display system comprising: First waveguide substrate and second waveguide substrate; A first dielectric layer and a second dielectric layer are inserted between a first waveguide substrate and a second waveguide substrate, wherein the second dielectric layer is edge-coupled with the first dielectric layer, and wherein the first dielectric layer has a first refractive index. A cross-coupler, the cross-coupler being in the first dielectric layer, wherein the first dielectric layer is configured to propagate the image light via total internal reflection, and the cross-coupler is configured to redirect the image light toward the second dielectric layer as the image light propagates through the first dielectric layer; An output coupler, wherein the output coupler is in the second medium layer and configured to couple the image light out of the second medium layer and toward the peephole; A first dielectric layer is inserted between the first dielectric layer and the first waveguide substrate, wherein the first dielectric layer is in direct contact with the first dielectric layer and the first waveguide substrate. and A second dielectric layer is inserted between the first dielectric layer and the second waveguide substrate, wherein the first dielectric layer and the second dielectric layer have a second refractive index different from the first refractive index.

10. The display system of claim 9, wherein the first dielectric layer has a first side surface coupled to the first dielectric layer, the first dielectric layer has a second side surface opposite to the first side surface and coupled to the second dielectric layer, and the first side surface and the second side surface are configured to reflect the image light when the image light propagates through the first dielectric layer.

11. The display system of claim 10, wherein the second dielectric layer is coupled to the edge of the first dielectric layer at an interface, and wherein image light enters the second dielectric layer from the first dielectric layer through the interface.

12. The display system of claim 9, wherein the first dielectric layer comprises an optically transparent adhesive and the second dielectric layer comprises an optically transparent adhesive.

13. The display system of claim 9, wherein the first refractive index is greater than or equal to 1.6, and the second refractive index is less than or equal to 1.

6.

14. The display system of claim 9, wherein the cross-coupler comprises a venetian blind mirror embedded in the first dielectric layer.

15. The display system of claim 9, wherein the output coupler comprises a volumetric hologram in the second dielectric layer.

16. The display system of claim 15, wherein the cross-coupler comprises a venetian blind mirror embedded in the first dielectric layer.

17. The display system of claim 15, wherein the second dielectric layer has a bulk refractive index that is less than the first refractive index.

18. The display system according to claim 9, further comprising: An input coupling prism is mounted to the first waveguide substrate and configured to couple the image light to the first dielectric layer.

19. A display system, comprising: A first dielectric layer, the first dielectric layer having opposing first side surfaces and second side surfaces; A second dielectric layer is coupled to the edge of the first dielectric layer at the interface; A first optically transparent adhesive layer is laminated onto the first dielectric layer, wherein the first optically transparent adhesive layer has a first refractive index; A second optically transparent adhesive layer is laminated onto the first dielectric layer, wherein the second optically transparent adhesive layer has a second refractive index; An input coupler configured to couple image light to a first dielectric layer, wherein the first dielectric layer is configured to propagate the image light via total internal reflection, wherein the first refractive index and the second refractive index of a first optically transparent adhesive layer and a second optically transparent adhesive layer are configured to confine the image light within the first dielectric layer when the image light propagates through the first dielectric layer via total internal reflection, wherein the image light is configured to enter the second dielectric layer from the first dielectric layer through the interface, and wherein the second dielectric layer is configured to propagate the image light via total internal reflection after the image light has passed through the interface; A cross-coupler, the cross-coupler being in the first dielectric layer and configured to redirect the image light toward the second dielectric layer when the image light propagates through the first dielectric layer via total internal reflection; and An output coupler, located in the second dielectric layer and configured to redirect the image light toward the trocar when the image light propagates through the second dielectric layer via total internal reflection.

20. The display system of claim 19, wherein the first dielectric layer has a third refractive index, and wherein the first refractive index and the second refractive index are different from the third refractive index.

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