Waveguide with tunable body reflector

Abstract

A waveguide for transmitting image light in a display device is disclosed. The waveguide includes a waveguide body, an input coupler configured to couple the image light into the waveguide body to cause the image light to propagate along a zigzag optical path within the waveguide body, and a plurality of ramped body reflectors configured to couple the image light into the waveguide body to cause the image light to propagate along the zigzag optical path within the waveguide body. The plurality of ramped body mirrors are disposed within the waveguide body along the zigzag optical path and have tunable reflectance parameters for controlling spatial distribution of image light portions coupled out of the waveguide body by the plurality of ramped body mirrors. The waveguide may include a plurality of tilted polarization selective body mirrors and a liquid crystal layer configured to change polarization of the image light, the liquid crystal layer disposed between a backplane electrode and a pixelated electrode configured to control the liquid crystal layer by applying a spatially varying voltage distribution.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 341,416, filed on May 12, 2022, entitled “ActiveEyebox Solutions and Application,” and to U.S. Provisional Patent Application No. 63 / 395,284, filed on August 4, 2022, entitled “Waveguide withTunable Bulk Reflectors,” and to U.S. Provisional Patent Application No. 63 / 405,698, filed on September 12, 2022, entitled “Waveguide withTunable Bulk Reflectors.” Technical Field

[0003] The present disclosure relates to visual display devices and related components, modules and methods. Background Art

[0004] Visual displays provide information, including still images, video, data, etc., to one or more viewers. Visual displays have applications in a variety of different fields, including entertainment, education, engineering, science, professional training, advertising, to name a few. Some visual displays (e.g., televisions) display images to multiple users, while some visual display systems (e.g., near-eye displays (NEDs)) are intended for a single user.

[0005] Artificial reality systems typically include a NED (e.g., a headset or a pair of glasses) configured to present content to a user. A near-eye display can display virtual objects or combine images of real objects with images of virtual objects, as in virtual reality (VR) applications, augmented reality (AR) applications, or mixed reality (MR) applications. For example, in an AR system, a user can view images of virtual objects (e.g., computer-generated images (CGI)) superimposed with the surrounding environment through a see-through "combiner" component. The combiner of a wearable display is typically transparent to external light, but includes some light routing optics to direct the display light into the user's field of view.

[0006] Because the display of a head-mounted display (HMD) or NED is typically worn on the head of a user, a large, bulky, cumbersome, unbalanced and / or heavy display device with a heavy battery would be cumbersome and uncomfortable for the user to wear. Accordingly, a head-mounted display device may benefit from a compact and efficient configuration, including an efficient light source and illuminator to provide illumination for the display panel, high-throughput eyepiece, and other optical elements in the image forming system. Summary of the invention

[0007] According to a first aspect of the present disclosure, there is provided a waveguide for transmitting image light in a display device, the waveguide comprising a waveguide body, an input coupler and a plurality of bulk slanted mirrors, the waveguide body comprising a first surface and a second surface opposite to each other, the first surface and the second surface extending parallel to each other; the input coupler being configured to couple the image light into the waveguide body so that the image light propagates along a zigzag optical path within the waveguide body, the zigzag optical path being defined by alternating reflections of the image light from the first surface and the second surface; the plurality of bulk slanted mirrors being arranged within the waveguide body along the zigzag optical path and having tunable reflectivity for controlling the spatial distribution of the image light portions coupled out of the waveguide body by the plurality of bulk slanted mirrors.

[0008] In an embodiment, a tilting body reflector of the plurality of tilting body reflectors comprises a voltage-controlled reflector having at least one of a reflectivity magnitude or a maximum reflectivity direction variable by applying a voltage to the voltage-controlled reflector.

[0009] In an embodiment, the tilted body reflectors among the multiple tilted body reflectors are polarization selective, and the waveguide also includes a liquid crystal layer located in the zigzag optical path within the waveguide body, so as to spatially selectively control the polarization state of the image light propagating along the zigzag optical path, thereby controlling the spatial distribution of these image light portions.

[0010] In an embodiment, the waveguide body includes a stack of: a substrate supporting the multiple tilted body mirrors; a backplane electrode; the liquid crystal layer; and a pixelated electrode layer for applying a spatially varying electric field to the liquid crystal layer by applying a spatially varying electric field between the backplane and the pixelated electrode layer; wherein the zigzag optical path passes through the stack.

[0011] In an embodiment, the input coupler comprises at least one tilting body reflector of the plurality of tilting body reflectors.

[0012] In an embodiment, the plurality of tilting body mirrors comprises a two-dimensional array or a three-dimensional array of tilting body mirrors.

[0013] In an embodiment, a plane of the two-dimensional array is parallel to the first surface and the second surface of the waveguide body.

[0014] In an embodiment, a plane of the two-dimensional array is non-parallel to the first surface and the second surface of the waveguide body.

[0015] In an embodiment, a tilting body reflector of the plurality of tilting body reflectors comprises a plurality of segments, each segment having an independently variable spatially uniform reflectivity.

[0016] According to a second aspect of the present disclosure, a display device is provided, the display device comprising an image projector and a waveguide, the image projector being configured to provide image light carrying an image in an angular domain; the waveguide being used to transmit the image light in the display device, the waveguide comprising a waveguide body, an input coupler and a plurality of tilting body reflectors, the waveguide body comprising a first surface and a second surface opposite to each other, the first surface and the second surface extending parallel to each other; the input coupler being configured to couple the image light into the waveguide body so that the image light propagates along a zigzag optical path in the waveguide body, the zigzag optical path being defined by alternating reflections of the image light from the first surface and the second surface; the plurality of tilting body reflectors being arranged in the waveguide body along the zigzag optical path and having a tunable reflectivity for controlling the spatial distribution of the image light portion coupled out of the waveguide body by the plurality of tilting body reflectors. In an embodiment, the second aspect comprises: an image projector configured to provide image light carrying an image in an angular domain; and a waveguide for transmitting image light in a display device according to the first aspect.

[0017] In an embodiment, each body reflector of the plurality of tilting body reflectors comprises a voltage-controlled reflector having at least one of a reflectivity magnitude or a maximum reflectivity direction that is variable by applying a voltage to the voltage-controlled reflector.

[0018] In an embodiment, each of the multiple inclined body reflectors is polarization selective, and the waveguide also includes a liquid crystal layer located in the zigzag optical path within the waveguide body, so as to spatially selectively control the polarization state of the image light propagating along the zigzag optical path, thereby controlling the spatial distribution of these image light portions.

[0019] In an embodiment, the display device of the second aspect also includes a controller, which is operably coupled to the waveguide body and is configured to control the reflectivity of the multiple tilting mirrors in a spatially selective manner based on a portion of the field of view currently displayed by the image projector.

[0020] In an embodiment, the display device of the second aspect also includes an eye tracking system and a controller, wherein the eye tracking system is configured to determine the position of the pupil of the user's eye at the eyebox of the display device; the controller is operably coupled to the waveguide body and the eye tracking system, and is configured to control the reflectivity of the multiple tilting mirrors in a spatially selective manner according to the pupil position determined by the eye tracking system.

[0021] In an embodiment, the display device is a near-eye display device.

[0022] According to a third aspect of the present disclosure, there is provided a method for transmitting image light from an image projector to an eye zone of a display device, the method comprising: coupling the image light into a waveguide body; causing the image light to propagate in the waveguide body along a zigzag optical path, the zigzag optical path being defined by alternating reflections of the image light from opposite first and second surfaces of the waveguide body; coupling part of the image light out of the waveguide body by using a plurality of tilting body reflectors, the plurality of tilting body reflectors being arranged in the waveguide body along the zigzag optical path and having tunable reflectivity; and controlling the spatial distribution of the portion of the image light coupled out of the waveguide body by the plurality of tilting body reflectors by tuning the reflectivity of the plurality of tilting body reflectors.

[0023] In an embodiment, controlling the spatial distribution of the image light portions comprises tuning a reflectivity of the plurality of tilted body mirrors by applying a voltage to each body mirror, each body mirror being a voltage controlled mirror.

[0024] In an embodiment, controlling the spatial distribution of the image light portion includes using a liquid crystal layer to control the polarization state of the image light propagating along the zigzag optical path in a spatially selective manner, the liquid crystal layer being disposed in the zigzag optical path within the waveguide body; and wherein each of the plurality of tilted body reflectors is polarization selective.

[0025] In an embodiment, controlling the spatial distribution of image light portions includes controlling the reflectivity of the plurality of tiltable body reflectors in a spatially selective manner based on a portion of the field of view currently displayed by the image projector to increase the portion of the image light portions that reaches the user's eyes: the image light portion carries the portion of the field of view displayed by the image projector.

[0026] In an embodiment, controlling the spatial distribution of image light portions includes determining the position of a pupil of a user's eye at an eye-adaptive zone of the display device; the method also includes controlling the reflectivity of the multiple tilted mirrors in a spatially selective manner based on the determined position of the eye pupil to increase the image light portions among the image light portions that reach the user's eyes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Exemplary embodiments will now be described with reference to the accompanying drawings, in which:

[0028] Figure 1A is a side cross-sectional view of a waveguide of the present disclosure, wherein a first tunable tilt body mirror is tuned to high reflection;

[0029] Figure 1B yes Figure 1A a side cross-sectional view of a waveguide of , wherein the second tunable tilt body mirror is tuned to high reflection and the first tunable tilt body mirror is tuned to high transmission;

[0030] Figure 2 yes Figure 1A and Figure 1B A magnified view of the tunable tilt body mirror of the waveguide;

[0031] Figure 3A is a partial side cross-sectional view of an example of a waveguide, wherein a liquid crystal layer and a waveguide body form a stack;

[0032] Figure 3B is a partial side cross-sectional view of an example of a waveguide in which a liquid crystal layer forms a stack with a tilted body reflector;

[0033] Figure 4 is used Figure 1A to Figure 1B or FIG. 3A to FIG. 3B Schematic diagram of a near-eye display with a waveguide;

[0034] Figure 5A is a side cross-sectional view of a waveguide tuned to couple out a first field of view (FOV) portion;

[0035] Figure 5B is tuned to couple out a different portion of the second FOV Figure 5A A side cross-sectional view of a waveguide;

[0036] Fig. 6A is a side cross-sectional view of a waveguide tuned to outcouple image light at a first eye location;

[0037] Figure 6B is a side cross-sectional view of a waveguide tuned to outcouple image light at a displaced second eye position;

[0038] Figure 7 is a flow chart of a method of transmitting image light from an image projector to an eye zone of a display device;

[0039] Fig. 8A is a side cross-sectional view of a waveguide including a tilted mirror having a tunable tilt angle;

[0040] Figure 8B yes Fig. 8ASide cross-sectional views of the waveguide at different positions of the viewer's eye;

[0041] Fig.9A yes Fig. 8A and Figure 8B A side cross-sectional view of a cholesteric liquid crystal embodiment of a waveguide under zero applied voltage;

[0042] Fig. 9B yes Fig. 8A and Figure 8B A side cross-sectional view of a cholesteric liquid crystal embodiment of a waveguide under an intermediate applied voltage;

[0043] Fig. 9C yes Fig. 8A and Figure 8B A side cross-sectional view of a cholesteric liquid crystal embodiment of a waveguide under maximum applied voltage;

[0044] Fig.10 yes 9A to 9C A graph showing the relationship between the reflectivity and angle of a waveguide;

[0045] Fig.11 is a top view of a waveguide of the present disclosure including a two-dimensional (2D) array of tilted body mirrors in an XY plane;

[0046] Fig.12 is a side cross-sectional view of a waveguide of the present disclosure including a 2D array of tilted body mirrors in the XZ plane;

[0047] Fig.13 is a side cross-sectional view of a waveguide of the present disclosure, the waveguide comprising a stack of two waveguide bodies and a tunable input coupler in an upper waveguide body;

[0048] Fig.14A is a plan view of a variable reflector of the present disclosure having two segments characterized by independently variable spatially uniform reflectivity;

[0049] Fig. 14B is a plan view of a variable reflector of the present disclosure having quadrant segments characterized by independently variable spatially uniform reflectivity;

[0050] Fig.15 is an illustration of a wearable display of the present disclosure having the form factor of a pair of glasses; and

[0051] Fig.16 is a three-dimensional view of a head mounted display (HMD) of the present disclosure. DETAILED DESCRIPTION

[0052] Although the present teachings are described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to these embodiments. On the contrary, as will be appreciated by those skilled in the art, the present teachings encompass a variety of alternatives and equivalents. All statements herein listing the principles, aspects, and embodiments of the present disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Furthermore, it is intended that these equivalents include both currently known equivalents and equivalents developed in the future, that is, any element developed to perform the same function, regardless of structure. Figure 1A to Figure 1B , FIG. 3A to FIG. 3B and Figures 11 to 13 In the drawings, like reference numerals denote like elements.

[0053] As used herein, unless explicitly stated, the terms "first", "second", etc. are not intended to imply a sequential order, but are intended to distinguish one element from another. Similarly, unless explicitly stated, the sequential order of the various method steps does not imply a sequential order in which they are performed.

[0054] Near-eye displays and augmented reality displays can use pupil-replicating waveguides to expand the image light carrying the projected image over the display's eye zone, i.e., the area where the user's eyes are likely to be located during normal operation of the display. Pupil-replicating waveguides are typically parallel flat plates of transparent material that cause the image light to propagate in a zigzag pattern by total internal reflection (TIR) ​​from the top and bottom surfaces of the waveguide.

[0055] One disadvantage of pupil replicating waveguides is that by spreading the image light over an extended area, a significant portion of the image light coupled into the pupil replicating waveguide never reaches the eye pupil, but instead illuminates the user's eyes and face. This results in a reduction in overall light utilization efficiency. Low light utilization efficiency can be compensated by using brighter light sources that require larger and heavier batteries, which increases the size and weight of the display. In addition, when the waveguide is part of an augmented reality system, the image light from the image source inside the augmented reality system must compete with external light in brightness to be seen by the viewer. In order for the generated image to be visible in broad daylight, the brightness of the augmented image may need to be increased by several orders of magnitude. In order to compete with the external light, the brightness of the internal image light source needs to be increased, which can be challenging. Therefore, it is very desirable to improve light utilization efficiency through pupil replicating waveguides.

[0056] According to the present disclosure, the light utilization efficiency of a near-eye display can be improved by providing a waveguide as follows: the waveguide includes a plurality of tilted body reflectors having individually tunable reflectivity magnitudes and / or directions of maximum reflectivity of the reflectors. In other words, the reflectivity magnitude and / or direction of the body reflector group can be tuned in a spatially selective manner. This enables the spatial distribution of the image light portion to be controlled to match the eye position in the eye-adaptive zone, and / or to correspond to a portion of the field of view currently displayed by the image projector. Customizing the spatial distribution of the image light for the eye position / gaze direction / portion of the FOV being displayed reduces the required brightness or total optical power of the image light generated by the image light source.

[0057] Reference now Figure 1A and Figure 1B , a waveguide 100 is shown in a side cross-sectional view. The waveguide 100 includes a waveguide body 101 having a first surface 111 and a second surface 112 opposite to each other, the first surface and the second surface extending parallel to each other. The first surface 111 and the second surface 112 opposite to each other may be outer surfaces of the waveguide body 101. The waveguide body 101 may include a transparent substrate, such as a glass, plastic, oxide, or inorganic crystal substrate. The transparent substrate may have a flat or curved outer surface and may be coated with a low refractive index material to prevent dust and fog.

[0058] The waveguide 100 includes an input coupler 102 configured to couple image light 120 into the waveguide body 101. The input coupler 102 may include a prism, a reflector with a constant or variable reflectivity, etc. The input coupler 102 may also include a linear polarizer for polarizing the incident image light. Upon entering the waveguide body 101, the image light 120 propagates within the waveguide body 101 through a series of total internal reflections (TIR) ​​from a first surface 111 and a second surface 112. The image light 120 propagates along a zigzag optical path 122 defined by alternating reflections of the image light 120 from the first surface 111 and the second surface 112 of the waveguide body 101. The image light 120 carries an image in an angular domain, i.e., an image in which each image element (pixel) is represented by a ray angle of a ray fan covering the entire FOV of the image. The brightness and / or color of a pixel of the image in the angular domain is represented by the brightness and / or color of the ray at the corresponding beam angle.

[0059] During the propagation of the image light 120 along the zigzag optical path 122, the image light 120 propagates through a plurality of tilted body mirrors 103, which are supported by the substrate of the waveguide body 101, for example, embedded in the substrate. The body mirrors 103 are arranged along the zigzag optical path 122. The body mirrors 103 can be tilted in a parallel manner, that is, they can be parallel to each other at the same tilt angle. Each body mirror 103 of the plurality of parallel tilted body mirrors 103 or at least some of such mirrors can have a tunable reflectivity. For example, the body mirror 103 can include a liquid crystal material and / or a multi-layer thin film coating. The body mirror 103 can be polarization selective, thereby reflecting incident light of one polarization and transmitting incident light of another orthogonal polarization. To this end, the body mirror can include a polarizing optical coating, such as a multi-layer dielectric coating.

[0060] The reflectivity magnitude of each body reflector 103 can be continuously tuned between a first state and a second state according to a control signal applied to each body reflector 103. When in the first state, the body reflector 103 has a set maximum reflectivity magnitude, thereby reflecting the image light 120 and coupling the image light 120 out of the waveguide body 101. When in the second state, the body reflector 103 is substantially transparent to the image light 120. Therefore, by tuning the reflectivity magnitude of at least one body reflector 103, the spatial distribution of the image light portion 121 coupled out of the waveguide body 101 by the plurality of parallel tilted body reflectors 103 can be controlled. In embodiments where the reflectivity magnitude of the body reflectors 103 is polarization selective, the reflectivity magnitude of at least one or more than one body reflector 103 can be independently tuned between the first state and the second state, but only for one polarization of the incident light.

[0061] In embodiments where the reflectivity magnitude is continuously tuned between the first state and the second state, the body reflector 103 may be tuned to be partially transparent to the image light 120. Similarly, tuning of the body reflector 103 may be accomplished using image light of different polarization states or multiple polarization states. Figure 1A The waveguide 100 is shown with all volume mirrors 103 in a first state (ie, substantially opaque to image light 120). Figure 1B Shown with Figure 1A 1 , wherein the reflectivity of the leftmost body mirror 103 is reduced, thereby allowing a larger portion 121 of the image light 120 to propagate further along the optical path 122, thereby shifting the lateral position of the outcoupled image light portion 121.

[0062] refer to Figure 2 , one of the plurality of body reflectors 103 is shown in an enlarged cross-sectional view. Figure 2The body reflector 103 includes an electrically responsive reflective layer 202 located between two transparent electrodes 204 coupled to an electrical terminal 201. When a voltage is applied to the terminal 201, the electrically responsive reflective layer 202 changes its reflectivity according to the magnitude of the applied voltage. In an embodiment where the material of the body reflector 103 is a liquid crystal material, when a voltage is applied, the reflectivity of the material changes because the liquid crystal molecules change their orientation. In some embodiments, the electrically responsive reflective layer 202 may include LiNbO3, LBO, KTP crystals, etc.

[0063] Reference now Figure 3A , Waveguide 300A is similar to Figure 1A and Figure 1B The waveguide 100 is similar to and includes similar elements. Figure 3A The waveguide 300A includes a waveguide body 301A having opposing first and second surfaces 311A, 312A, the first and second surfaces extending parallel to each other. The waveguide body 301A may include a transparent substrate, such as glass, plastic, oxide, and / or an inorganic crystal substrate. The waveguide 300A includes an input coupler 302 configured to couple image light 320 into the waveguide body 301A, such as a coupling prism (as shown) and / or a coupling mirror. For example, the input coupler 302 may include a polarizing element such as a linear polarizer.

[0064] The waveguide body 301A also includes a liquid crystal (LC) cell 360A including an LC layer 304 defined by a transparent substrate having opposing first and second inner surfaces 313 and 314. The LC layer 304 may include an LC fluid composed of LC molecules 304A (e.g., nematic or cholesteric LC molecules). The transparent substrate may be made of, for example, glass, plastic, fused quartz, metal oxides, and / or inorganic crystals, to name a few examples. In some embodiments, the waveguide body 301A may be used as a top substrate of the LC cell 360A, i.e., the LC cell 360A may not have a separate dedicated top substrate.

[0065] Regardless of implementation, the top substrate of the LC cell 360A can support a backplane electrode layer 305 disposed between the substrate of the waveguide body 301A and the liquid crystal layer 304. The LC cell 360A can include a pixelated electrode layer 306 for applying a spatially varying electric field between the backplane electrode 305 layer and individual pixels 306A of the pixelated electrode layer 306 and across the LC layer 304. The electric field causes the LC molecules 304A to change their spatial orientation within the corresponding pixels 306A. The voltage-dependent orientation of the LC molecules 304A defines a local birefringence property of the LC layer 304, thereby allowing the LC layer 304 to change the polarization state of the image light 320 propagating through the LC layer 304. Due to the pixelated nature of the bottom electrode layer 306, the polarization state of the image light 320 can be controlled in a spatially selective manner to provide a desired change in the polarization state of the image light 320 as the image light 320 propagates in the waveguide body 301A.

[0066] The waveguide body 301A may further include a plurality of polarization selective tilted body reflectors 303. These body reflectors 303 may be parallel to each other. After being coupled into the waveguide body 301A through the input coupler 302, the image light 320 propagates within the waveguide body 301A (including the backplane electrode layer 305 and the liquid crystal layer 304) along a zigzag optical path 322A through a series of TIRs from the first surface 311A ​​of the waveguide body 301A and the outer surface of the LC cell 360A (e.g., from the outer surface of its bottom transparent substrate), as shown. The waveguide body 301A, the liquid crystal layer 304, and the backplane electrode layer 305 may form a stack that is substantially transparent to the image light 320 so that the image light 320 propagates within the stack. The refractive indices of the substrates of the waveguide body 301A, the liquid crystal layer 304, and the backplane electrode layer 305 may be matched, thereby reducing undesirable Fresnel reflections of the image light 320 on the optical path 322A through the stack.

[0067] Image light 320 propagates sequentially through polarization-selective volume reflectors 303 and LC layer 304. Liquid crystal layer 304 is configured to control the polarization state of image light 320 in a spatially selective manner, thereby controlling the size or optical power level of image light portions 321 coupled out by each polarization-selective volume reflector 303. Thus, the spatial distribution of image light portions 321 can be controlled by applying voltages to each pixel 306A of pixelated electrode layer 306. The voltage pattern applied across LC cell 360A defines the spatial distribution of coupled-out image light portions 321 in a predictable, controllable manner.

[0068] Go to Figure 3B , Waveguide 300B is Figure 3A A variation of the waveguide 300A and including similar elements. Figure 3BThe waveguide 300B includes a waveguide body 301B having a first outer surface 311B and a second outer surface 312B opposite to each other, the first outer surface and the second outer surface extending parallel to each other. The waveguide body 301B may include a transparent substrate, such as glass, plastic, oxide and / or an inorganic crystal substrate. The waveguide 300B includes an input coupler 302, such as a coupling prism (as shown) and / or a coupling reflector, which is configured to couple the image light 320 into the waveguide body 301B. For example, the input coupler 302 may include a polarization element such as a linear polarizer.

[0069] The waveguide body 301B may further include a plurality of polarization selective tilted body reflectors 303. The body reflectors 303 may be parallel to each other. After being coupled into the waveguide body 301B by the input coupler 302, the image light 320 propagates in the waveguide body 301B along a zigzag optical path 322B through a series of TIRs from the first surface 311B and the second surface 312B of the waveguide body 301B.

[0070] The waveguide body 301B may also include a plurality of LC cells 360B located upstream of each body reflector 303 in the optical path 322B as shown, although in some embodiments, the LC cells 360B may be disposed downstream of the corresponding body reflector 303. The LC cells 360B generally include Figure 3A 303, the LC cell 360B may be provided with similar elements / layers to the LC cell 360A of the embodiment of the present invention, but the LC cell 360B does not need to include a pixelated electrode layer, that is, the LC cell 360B may include a pair of continuous (unpatterned) transparent electrodes for uniformly performing polarization control over the entire LC cell 360B. As shown in the figure, the LC cell 360B may be disposed near and / or parallel to the corresponding body reflector 303, and may form a stack with the corresponding body reflector 303.

[0071] The purpose of the LC cell 360B is to control the polarization state of the image light 320 along the optical path 322B, and accordingly control the spatial distribution of the outcoupled portion 321 of the image light 320 via the polarization state of the image light 320. For example, if the body mirror 303 is configured to reflect light of a first linear polarization and transmit light of an orthogonal second polarization, then when it is desired to be outcoupled by the corresponding one or more downstream body mirrors 303, one or more LC cells 360B can be tuned to convert the polarization state of the image light 320 to the first polarization state. By the same principle, when the corresponding body mirror 303 is to cause the image light 320 to propagate through the body mirror 303, one or more LC cells 360B can be tuned to convert the polarization state of the image light 320 to the second polarization state. Of course, at intermediate polarization states of image light 320, controllable portion 321 of image light 320 may be coupled out, and depending on the desired spatial distribution of the optical power distribution of image light portion 321, one or more LC boxes 360B may be tuned to provide one or more desired controllable portions of image light 320 to be coupled out of waveguide body 301B.

[0072] Reference now Figure 4 And further reference Figure 1A The display device 430 includes an image projector 433 and a waveguide 400, wherein the image projector 433 is configured to provide image light 420 carrying an image in an angular domain, and the waveguide 400 is used to transmit the image light 420 carrying the image in the angular domain to the eye area 450 for viewing by the user's eye 404. For example, Figure 4 The waveguide 400 may include Figure 1A to Figure 1B Waveguide 100, Figure 3A Waveguide 300A or Figure 3B The image projector 433 may be, for example, a scanning image projector, or may be based on a micro display panel coupled to a collimator. In the illustrated embodiment, the display device 430 is a near-eye display device that provides image light 420 to an eye zone 450.

[0073] The display device 430 may further include a controller 431 operably coupled to the waveguide body 401 (e.g., coupled to each of the plurality of tilted body mirrors 403 of the waveguide body 401) and / or coupled to the LC cell (e.g., Figure 3A The LC box 360A depicted in FIG. Figure 3B LC box 360B depicted in FIG. 4 ). Controller 431 ( Figure 4) can be configured to control the reflectivity of the plurality of tilted body mirrors 403 in a spatially selective manner by controlling the reflectivity of each body mirror 403 and / or by controlling the polarization state of the image light with the polarization selective body mirror 403. The controller 431 is also operably coupled to an image projector 433. The image projector 433 can be, for example, a scanning projector that presents a FOV by scanning a collimated light beam, or a microdisplay-based projector.

[0074] In operation, the controller 431 may control the spatial distribution of the reflectivity of the body mirror 403 based on information about a portion of the field of view (FOV) currently displayed by the image projector 433. The controller 431 may be configured to control the image projector 433 to generate the image light 420 according to the portion of the FOV currently displayed by the image projector 433. According to the present disclosure, the controller 431 may be configured to increase the portion of the image light 420 that reaches the eye 404: the image light portion carries the portion of the FOV currently displayed by the image projector.

[0075] The display device 430 may also include an eye tracking system 432 for determining at least one of a position or orientation of the eye 404 in the eye zone 450. The controller 431 may be operably coupled to the eye tracking system 432 for determining the instantaneous position of the pupil 405 of the eye 404 in the eye zone 450 of the display device 430 based on the determined position and orientation of the eye 404. The eye tracking system 432 may update information about the position of the pupil 405 of the user's eye 404 in real time. The controller 431 may be configured to control the reflectivity of the plurality of tilting body mirrors 403 based on information received from the eye tracking system 432 and / or based on the current FOV portion displayed by the image projector 433. The controller 431 may be configured to increase the portion of the image light 420 portion 421 directed to the eye pupil 405 while attenuating the portion of the image light 421 that does not reach the eye pupil 405, thereby saving power by better utilizing the image light 420. By redistributing image light portion 421 to propagate primarily toward eye pupil 405 , controller 431 increases the optical power level of image light 420 reaching eye pupil 405 , thereby significantly improving the wall plug efficiency of display device 430 .

[0076] Figure 5A and Figure 5B It is shown how the image light can be coupled out of the waveguide in a FOV-dependent manner. Figure 5A and Figure 5B A portion of a waveguide body 501 is shown, and the waveguide body 501 is similar to Figure 4 The waveguide body 401 is provided. Figure 5Aand Figure 5B The waveguide body 501 includes opposite upper and lower surfaces 511 and 512 and two tunable mirrors 503A and 503B in between. At a first moment, the image light carries a first portion of the FOV represented by the first ray 520A. In order to transmit the first FOV portion to the position of the pupil 505 of the user's eye 504, the left body mirror 503A is tuned to a substantially opaque total reflection state, or to a mainly reflective state and a partially transparent state. Most of the image light is reflected by the left body mirror 503A and coupled out as a first beam portion (first ray 521) propagating toward the pupil 505 of the user's eye 504.

[0077] At a subsequent second moment, the image light may carry the FOV as given by Figure 5B The second portion of the image light is represented by the second light ray 520B in the left body reflector 503A. The reflectivity of the left body reflector 503A is reduced to propagate most of the image light further to the right body reflector 503B. The image light 520 propagates through the left body reflector 503A as substantially unaffected light ray 522. The right body reflector 503B is tuned to a state of total reflection, or to a state of increased reflectivity. Most or all of the image light is reflected by the right body reflector 503B and coupled out as light ray 522 toward the user's eye pupil 505. The reflected light ray 522 ( Figure 5B ) reaches and reflects light 521( Figure 5A ) are substantially in the same spatial position. Body mirrors 503A and 503B can be tuned to a non-total reflective state to provide smoother light control (no clear boundaries between different FOV parts for easier viewing) and avoid sharp drops in brightness due to rapid eye movements.

[0078] Fig. 6A and Figure 6B It is shown how image light 620 can be coupled out depending on the eye pupil position in the eye zone, so that the outcoupled light follows the instantaneous eye pupil position. Fig. 6A and Figure 6B A portion of a waveguide body 601 is shown. Figure 4 The waveguide body 401 is similar to that of FIG. 401 and operates in a similar manner. Fig. 6A and Figure 6B The waveguide body 601 includes an upper surface 611 and a lower surface 612 opposite to each other, and tunable body reflectors 603A, 603B, 603C and 603D disposed between the upper surface 611 and the lower surface 612 .

[0079] First reference Fig. 6A, the user's eye 604 is located to the left of the waveguide portion shown. To direct the image light 620 to the current position of the eye 604, the two leftmost body mirrors 603A and 603B are tuned to a higher reflectivity state. A larger portion of the image light 620 is reflected by the two leftmost body mirrors 603A and 603B and coupled out as a cone of light 621 that propagates toward the user's eye pupil 605, so that a larger portion of the image light 620 can reach the user's eye 604.

[0080] Go to Figure 6B and with Fig. 6A By comparison, the user's eye 604 is displaced to the right and is located on the right side of the waveguide as shown. Image light 620 is Fig. 6A The same angle is incident on the four body reflectors 603A to 603D. The two body reflectors 603A and 603B on the far left are tuned to reduce their reflectivity, for example, to substantially zero or very low reflectivity, so that the propagated image light 620 is substantially transparent.

[0081] The image light 620 propagates substantially through the two leftmost body mirrors 603A and 603B without losing its optical power level. The two rightmost body mirrors 603C and 60D are tuned to have a higher reflectivity level. The image light 620 is reflected by the two rightmost body mirrors 603C, 603D and coupled out as a light cone 622 towards the user's eye pupil 605.

[0082] As the user looks at different objects displayed by the display device, and / or as the user shifts the eye relative to the display device (which may occur, for example, during adjustment of the AR goggles on the user's face), the outcoupled light may follow the eye pupil position from one position to another. Depending on the eye position and interpupillary distance of different users of the AR goggles, portions of the image light may be outcoupled. Fig. 6A The two outcoupled light rays 621 and Figure 6B The two outcoupled light rays 622 are boundary rays of the outcoupled light cone corresponding to the outcoupled FOV. The body mirrors 603A to 603D may be continuously tunable to provide smoother light control without sudden drops in optical power between different eye positions.

[0083] Reference now Figure 7 And further reference Figure 4 , a method 700 for transmitting image light to an eye zone of a display device through a display device is proposed. The method 700 can be used, for example, to transmit image light 420 emitted by an image projector 433 to an eye zone 450 ( Figure 4 ).

[0084] Method 700 includes coupling image light 420 into ( Figure 7 701) into the waveguide body, for example, using a coupler 402 to couple the image light 420 into the waveguide body 401. In some embodiments, the image light 420 may be polarized.

[0085] After entering the waveguide body 401, the image light 420 propagates in the waveguide body 401 along a zigzag image light path defined by the alternating reflection of the image light 420 from the first surface 411 and the second surface 412 of the waveguide body 401 (702). When the image light 420 propagates along the zigzag path, the image light 420 sequentially propagates through the plurality of tilting body reflectors 403. The tilting body reflectors 403 have tunable reflectivity. The tunable reflectivity can be achieved by applying a voltage to each tilting body reflector 403 (as described above with reference to FIG. 1 ). Figure 2 ), and / or by using a liquid crystal layer in combination with a polarization selective volume mirror (as explained above with reference to Figure 3A and Figure 3B explained).

[0086] Part of the image light is reflected from the waveguide body ( Figure 4 )Decoupling( Figure 7 ; 703). The outcoupling occurs by reflection of the image light 420 from the surface of the body reflector 403. Part or all of the image light 420 may be coupled out by any one of the body reflectors 403. The combination of the multiple image light 420 portions 421 coupled out from the corresponding body reflectors 403 forms an image in the angular domain at the eye zone 450 of the display device 430.

[0087] The reflectivity of each of the plurality of tilting body mirrors 403 can be tuned to control ( Figure 7 ; 704) spatial distribution of image light portions coupled out of the waveguide body 401 by the plurality of tilted body mirrors 403. Each body mirror 403 can be tuned independently of another body mirror 403. More than one body mirror 403 can be tuned together, simultaneously or sequentially to provide a desired distribution of optical power density of the coupled out image light portions.

[0088] In some embodiments, the reflectivity of the body mirror 403 may be tuned (704A) by applying a set of voltages to the body mirror 403. The reflectivity of the plurality of tilted body mirrors 403 may be tuned (704C) in a spatially selective manner based on a portion of the field of view currently displayed by the image projector 433 to, for example, increase (704C1) the portion of the image light portions 420 that reach the user's eye that carry the portion of the field of view currently displayed by the image projector 433. In some embodiments, tuning the voltage controlled reflectivity of the body mirror 403 may be accomplished based on determining (704D) the position of the pupil of the user's eye at the eye zone of the display device 430 to, for example, increase (704D1) the portion of the image light portions that are directed precisely to the eye pupil. Furthermore, in some embodiments, the reflectivity of the body mirror may be tuned based on both the portion of the FOV currently displayed and the current position of the eye pupil.

[0089] Still refer to Figure 7 And further reference FIG. 3A to FIG. 3B and Figure 4 , the spatial distribution of the outcoupled image light 320 can be controlled by controlling the polarization state of the image light 320 ( Figure 7 ; 704). The polarization state can be controlled by using one or more liquid crystal layers, as described above with reference to Figure 3A and Figure 3B As explained above, the polarization state of image light 320 propagating along image light 320 path 322A or 322B is controlled (704B) in a spatially selective manner. In such an embodiment, each body mirror 303 of the plurality of tilted body mirrors 303 can be made polarization selective to provide a reflectivity that varies depending on the polarization state of the incident image light. In other embodiments, some body mirrors 303 are polarization selective and some body mirrors 303 are not polarization selective. For clarity, reference is made to Figure 3A In the embodiment 300A depicted in FIG. 3 , the liquid crystal layer 305 and the volume reflector 303 are arranged in a sawtooth optical path 322A within the waveguide body 301A. As the image light 320 propagates along the optical path 322A, the polarization state of the image light 320 changes according to the desired optical power density distribution of the outcoupled image light portion.

[0090] Controlling 704 the spatial distribution of the outcoupled image light 320 portion by controlling the polarization of the image light may include: controlling 704C the reflectivity of the plurality of tilting body mirrors 303 in a spatially selective manner based on a portion of the field of view currently displayed by the image projector, thereby increasing (704C1) the portion of the image light 320 portion that carries the portion of the field of view displayed by the image projector. In some embodiments, controlling (704) the spatial distribution of the outcoupled image light 320 portion includes: determining the position of the pupil of the user's eye 404 at the eye zone of the display device 430, and redistributing the outcoupled image light portion by controlling the spatial distribution of the polarization of the image light in dependence on the polarization-dependent reflectivity of the plurality of tilting mirrors 303. Such control may be performed based on the determined position (704D) of the pupil 405, thereby increasing 704D1 the portion of the image light 320 portion that is directed to the pupil of the eye. The purpose of controlling the reflectivity of the tilting body reflector in relation to the eye pupil position and / or FOV is to redistribute the optical power of the outcoupled image light portion to direct most of the image light to the current eye pupil position while avoiding irradiating the eye-adaptive zone portion where the eye pupil does not exist, thereby avoiding unnecessary light loss and significantly improving the overall efficiency of light utilization of the display device. The above considerations also apply to Figure 3B Waveguide embodiment 300B.

[0091] In the waveguides and methods considered herein, not only the reflectivity magnitude but also the direction of maximum reflectivity, i.e. the effective tilt angle of the tilted reflector, can be controlled / tuned to redirect the output image light more flexibly. Therefore, the term "reflectivity" should be understood to refer to the magnitude and / or the direction of maximum reflectivity, i.e. the direction of the outcoupled light.

[0092] refer to Fig. 8A and Figure 8B As a non-limiting illustrative example, the waveguide 800 includes a plurality of tilted reflectors 803 having tunable tilt angles. When the eye 804 of a user of the display is in a position such as Fig. 8A In the first position shown, the tilt angle of the reflector 803 is selected to direct the portion 821 of the outcoupled image light toward the first position. Figure 8B As shown, when the eye 804 moves to a position such as that determined by an eye tracking system (e.g., Figure 4 When the second position is determined by the eye tracking system 432 in the image processing apparatus, the tilt angle of the reflector 803 is adjusted to guide the portion 821 of the coupled image light toward the second position.

[0093] Embodiments of waveguides with tilted mirrors (these mirrors have tunable tilt angles / directions of maximum reflectivity) are described in 9A to 9C First refer to Fig.9A, the waveguide 900 includes a cholesteric LC layer 904 having LC molecules 924 between a pair of transparent electrodes 905, 906. The LC molecules 924 form a helix 925 that operates as a reflector whose tilt angle is controlled by a voltage. By applying a voltage between the electrodes 905, 906, the helix angle can be controlled. For example, in Figure A, the voltage is zero and the helix 925 is arranged perpendicular to the electrodes 905, 906. In Figure 1B In the embodiment, a non-zero voltage V1 is applied to cause the spiral 925 to tilt. The tilt angle increases with the increase of the voltage, as can be seen by comparing Fig. 9B and Fig. 9C It can be seen that in Fig. 9C In the embodiment, the applied voltage is increased to a value V2, V2>V1.

[0094] Fig.10 9 shows the effect of applied voltage on the direction of maximum reflectivity of image light by the variable angle reflector formed by the spiral 925. The dashed bell-shaped curve 1000A corresponds to the reflectivity at zero applied voltage, i.e. Fig.9A The situation shown in the dashed bell curve 1000B corresponds to the reflectivity when the applied voltage is V1, that is Fig. 9B and the solid bell-shaped curve 1000C corresponds to the reflectivity when the applied voltage is V2, that is Fig. 9C It can be seen that as the voltage applied to the electrodes 905, 906 increases, the maximum reflectivity directions corresponding to the peaks of the bell-shaped curves 1000A, 1000B and 1000C shift towards higher angle values.

[0095] In some embodiments, the angled body reflectors of the waveguide body can form a two-dimensional (2D) array or a three-dimensional (3D) array of mirrors to provide additional flexibility in image light outcoupling and redirection. Fig.11 By way of illustrative, non-limiting example, waveguide 1100 is similar to waveguide 100 of FIG. 1 and includes similar elements. Fig.11 The waveguide 1100 in the embodiment includes a waveguide body 1101 having a first surface 1111 and a second surface 1112 opposite to each other (the first surface and the second surface extend parallel to each other), for example, flat parallel surfaces. Fig.11 In the top view, the first surface 1111 and the second surface 1112 are disposed one below the other.

[0096] The input coupler 1102 is configured to couple the image light into the waveguide body 1101 so as to allow the image light to travel along the same direction as the above reference direction in the waveguide body 1101. Figure 1A , Figure 1BThe explained zigzag light path is similar to the zigzag light path propagation. The zigzag light path is defined by the alternating reflection of the image light from the first surface 1111 and the second surface 1112.

[0097] A plurality of tilting body reflectors 1103 are arranged along a zigzag optical path in the waveguide body 1101. The tilting body reflectors 1103 have a tunable reflectivity for controlling the spatial distribution of the image light portion coupled out from the waveguide body 1101 by the plurality of tilting body reflectors 1103, which is similar to the above reference Figure 1A to Figure 1B , Figure 2 as well as FIG. 3A to FIG. 3B As shown in the figure, the tilted body reflector 1103 forms a 2D array of tilted body reflectors. The plane of the 2D array is parallel to the surfaces 1111, 1112 of the waveguide body 1101, that is, parallel to Fig.11 The term "plane of the 2D array" herein refers to a plane in which the center of the tilting body reflector 1103 is arranged. The 2D array enables the tilting body reflector 1103 to be tilted in two dimensions, namely in the X direction and in the Y direction, as described above with reference to Figure 4 and Figure 7 The FOV and / or output optical power distribution can be controlled as explained.

[0098] Steering Fig.12 , waveguide 1200 is similar to waveguide 100 of FIG. 1 and includes similar elements. Fig.12 The waveguide 1200 includes a waveguide body 1201 having a first surface 1211 and a second surface 1212 opposite to each other (the first surface and the second surface extend parallel to each other), for example, flat parallel surfaces. Figure 1A and Figure 1B As explained, the image light propagates along a zigzag optical path within the waveguide body 1201. The zigzag optical path is defined by alternating reflections of the image light from the first surface 1211 and the second surface 1212.

[0099] The plurality of tilting body reflectors 1203 are arranged along the zigzag optical path in the waveguide body 1201. The tilting body reflectors 1203 have tunable reflectivity for controlling the spatial distribution of the image light portions coupled out from the waveguide body 1201 by the plurality of tilting body reflectors 1203, as described above with reference to Figure 1A to Figure 1B , Figure 2 and FIG. 3A to FIG. 3B Explained.

[0100] The tilted body reflector 1203 forms a 2D array of tilted body reflectors in the XZ plane, so that the plane of the two-dimensional array is not parallel to the first surface 1211 and the second surface 1212 of the waveguide body 1201. This configuration enables independent performance control of image light propagation and outcoupling in the top and bottom parts (with respect to the Z axis) of the waveguide body 1201, which enables improved uniformity of the outcoupled image light portion.

[0101] refer to Fig.13 , the waveguide 1300 includes not one but two waveguide bodies, namely a first waveguide body 1301-1 having a first input coupler and a second waveguide body 1301-2 having a second input coupler. The first input coupler includes a first tilted body reflector 1302-1 located in the first waveguide body 1301-1. The first tilted body reflector 1302-1 can be tunable to couple a controllable portion of the image light 1320 into the first waveguide body 1301-1 so as to propagate along a first zigzag optical path 1322-1 within the first waveguide body 1301-1, and the first zigzag optical path 1322-1 is defined by alternating reflections of the image light from parallel outer surfaces of the first waveguide body 1301-1. A first plurality of tilted body reflectors 1303-1 are arranged within the first waveguide body 1301-1 along the first zigzag optical path 1322-1. The reflector 1303-1 in the first plurality of tilting mirrors can be a reflector with a constant reflectivity or a reflectivity tunable reflectivity.

[0102] The second input coupler includes a second tilted body mirror 1302-2 located in the second waveguide body 1301-2. The second tilted body mirror 1302-2 can have a fixed reflector or a tunable reflectivity. The second tilted body mirror 1302-2 can be configured to couple the remaining portion of the image light 1320 into the second waveguide body 1301-2 so as to propagate along a second zigzag optical path 1322-2 within the second waveguide body 1301-2, the second zigzag optical path 1322-2 being defined by alternating reflections of the image light from parallel outer surfaces of the second waveguide body 1301-2.

[0103] The second plurality of tilted body mirrors 1303-2 are disposed within the second waveguide body 1301-2 along the second zigzag optical path 1322-2. The mirrors 1303-2 in the second plurality of tilted body mirrors may have a constant reflectivity or a tunable reflectivity.

[0104] In operation, the first tilting body reflector 1302-1 is tuned to a high reflectivity or a low reflectivity depending on a desired position in the eye zone 1350 to be illuminated with the image light 1320. For example, when the first tilting body reflector 1302-1 is tuned to a high reflectivity, most or all of the image light 1320 propagates in the first waveguide body 1301-1 along the first sawtooth optical path 1322-1 and is thus coupled out of the first waveguide body 1301-1 at a first position 1351. When the first tilting body reflector 1302-1 is tuned to a low reflectivity, most or all of the image light 1320 propagates in the second waveguide body 1301-2 along the second sawtooth optical path 1322-2 and is coupled out of the second waveguide body 1301-2 at a displaced second position 1352. Such a configuration may be more convenient than, for example, Figure 1A and Figure 1B The configuration of the waveguide 100 in FIG. 1301 is simpler because it only requires one tunable mirror. In other words, only one tilted body mirror among all body mirrors supported by the first waveguide body 1301 - 1 needs to be tunable to have a certain ability to redistribute the image light 1320 over the eye zone 1350 .

[0105] In some embodiments, the first tilting body reflector 1302-1 is polarization selective, for example, comprises a reflective polarizer, and the image light power balance between the first waveguide body 1301-1 and the second waveguide body 1301-2 can be adjusted by tuning the polarization state of the image light 1320. Furthermore, in some embodiments, the waveguide assembly can include more than two waveguide bodies, all of which, except for the most downstream waveguide body, have respective tunable couplers.

[0106] Go to Fig.14A Variable reflector 1400A can be used as a variable tilt body reflector in any of the waveguides described above, including one or more in-coupling and / or out-coupling tilt mirrors. Variable reflector 1400A includes a first segment 1401 and a second segment 1402 having independently variable spatially uniform reflectivities. This can be accomplished by providing a segmented electrically responsive reflective layer (e.g., Figure 2 This can be achieved by layer 202 in the middle), a segmented liquid crystal cell, followed by a reflective polarizer, etc.

[0107] refer to Fig. 14B , the variable mirror 1400B can be used as a variable tilt body reflector in any of the above-mentioned waveguides, including one or more coupling-in and / or coupling-out mirrors / reflectors. Fig. 14BThe variable reflector 1400B includes not two but four individually controlled reflector segments, specifically first quadrant segment 1411, second quadrant segment 1412, third quadrant segment 1413 and fourth quadrant segment 1414 based on an electro-responsive reflective layer, a liquid crystal segment cell and a reflective polarizer, etc. The segmented variable reflector allows for finer control over the distribution of the optical power of the outcoupled image light portion.

[0108] Reference now Fig.15 , the augmented reality (AR) near-eye display 1500 is Figure 4 An embodiment of a display device 430. Fig.15 The AR near-eye display 1500 includes a frame 1501 that supports, for each eye, a light engine or image projector 1530 for providing an image beam carrying an image in an angular domain, a pupil replicating light guide 1506 based on any of the waveguides disclosed herein for providing multiple offset portions of the image beam to spread the image in the angular domain over an eye zone 1512, and a plurality of eye zone illuminators 1510, which are shown as black dots, with clear apertures around the pupil replicating light guide 1506 spread over a surface facing the eye zone 1512. An eye tracking camera 1504 may be provided for each eye zone 1512.

[0109] The purpose of eye tracking camera 1504 is to determine the position and / or orientation of the user's eyes. Eye zone illuminator 1510 illuminates the eye at a corresponding eye zone 1512, thereby allowing eye tracking camera 1504 to obtain an image of the eye, as well as provide a reference reflection, i.e., a glint. The glint can be used as a reference point in the captured eye image, thereby facilitating the determination of the eye gaze direction by determining the position of the eye pupil image relative to the glint position. In order to avoid the light of eye zone illuminator 1510 distracting the user, eye zone illuminator 1510 can be made to emit light that is invisible to the user. For example, infrared light can be used to illuminate eye zone 1512.

[0110] Go to Fig.16, HMD 1600 is an example of an AR / VR wearable display system that surrounds the user's face for greater immersion in an AR / VR environment. HMD 1600 can generate fully virtual 3D images. HMD 1600 may include a front body 1602 and a band 1604 that can be fixed around the user's head. The front body 1602 is configured to be placed in front of the user's eyes in a secure and comfortable manner. A display system 1680 may be provided in the front body 1602 for presenting AR / VR images to the user. The display system 1680 may include any of the display devices and illuminators disclosed herein. The side 1606 of the front body 1602 may be opaque or transparent.

[0111] In some embodiments, the front body 1602 includes a locator 1608 and an inertial measurement unit (IMU) 1610 for tracking the acceleration of the HMD 1600, and a position sensor 1612 for tracking the position of the HMD 1600. The IMU 1610 is an electronic device that generates data indicating the position of the HMD 1600 based on measurement signals received from one or more position sensors 1612, which generate one or more measurement signals in response to the movement of the HMD 1600. Examples of the position sensor 1612 include one or more accelerometers, one or more gyroscopes, one or more magnetometers, another suitable type of sensor that detects movement, a sensor type used for error correction of the IMU 1610, or some combination thereof. The position sensor 1612 can be located outside the IMU 1610, inside the IMU 1610, or some combination thereof.

[0112] The locator 1608 is tracked by an external imaging device of the virtual reality system, so that the virtual reality system can track the position and orientation of the entire HMD 1600. The information generated by the IMU 1610 and the position sensor 1612 can be compared with the position and orientation obtained by tracking the locator 1608 to improve the tracking accuracy of the position and orientation of the HMD 1600. When the user moves and turns in 3D space, accurate position and orientation are very important to present the user with an appropriate virtual scene.

[0113] The HMD 1600 may also include a depth camera assembly (DCA) 1611 that collects data describing depth information of a local area surrounding some or all of the HMD 1600. The depth information may be compared with information from the IMU 1610 in order to more accurately determine the position and orientation of the HMD 1600 in 3D space.

[0114] The HMD 1600 may also include an eye tracking system 1614 for determining the orientation and position of the user's eyes in real time. The position and orientation of the eyes obtained also allow the HMD 1600 to determine the user's gaze direction and adjust the images generated by the display system 1680 accordingly. The determined gaze direction and convergence angle can be used to adjust the display system 1680 to reduce the convergence-accommodation conflict. As disclosed herein, the direction and convergence can also be used for the exit pupil steering of the display. In addition, the determined convergence and gaze angle can be used to interact with the user, highlight objects, bring objects to the foreground, create additional objects or pointers, etc. An audio system may also be provided, including, for example, a set of small speakers built into the front body 1602.

[0115] Embodiments of the present disclosure may include an artificial reality system, or be implemented in conjunction with an artificial reality system. The artificial reality system adjusts the sensory information about the outside world obtained through the senses in some way (e.g., visual information, audio, touch (body) information, acceleration, balance, etc.), and then presents it to the user. As a non-limiting example, artificial reality may include virtual reality (VR), augmented reality (AR), mixed reality (MR), hybrid reality, or some combination and / or derivative thereof. Artificial reality content may include fully generated content, or generated content combined with collected (e.g., real-world) content. Artificial reality content may include video, audio, somatic or tactile feedback, or some combination thereof. Any of these contents may be presented in a single channel or in multiple channels (e.g., in a stereoscopic video that produces a three-dimensional effect to the viewer). In addition, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, which are used, for example, to create content in artificial reality and / or otherwise used in artificial reality (e.g., performing activities in artificial reality). Artificial reality systems that provide artificial reality content can be implemented on a variety of platforms, including wearable displays (e.g., HMDs connected to a host computer system), standalone HMDs, near-eye displays with eyeglass form factors, mobile devices or computing systems, or any other hardware platform capable of providing artificial reality content to one or more viewers.

[0116] The scope of the present disclosure is not limited by the specific embodiments described herein. In fact, in addition to the embodiments and modifications described herein, various other embodiments and modifications will be apparent to those of ordinary skill in the art according to the foregoing description and accompanying drawings. Therefore, such other embodiments and modifications are intended to fall within the scope of the present disclosure. In addition, although the present disclosure has been described herein in the context of a specific embodiment in a specific environment for a specific purpose, those of ordinary skill in the art will recognize that the usefulness of the present disclosure is not limited thereto, and the present disclosure can be beneficially implemented in any number of environments for any number of purposes. Therefore, the claims set forth should be interpreted according to the full scope of the present disclosure as described herein.

Claims

1. A waveguide for transmitting image light in a display device, the waveguide comprising: a waveguide body comprising opposing first and second surfaces, the first and second surfaces extending parallel to each other; an input coupler configured to couple the image light into the waveguide body so that the image light propagates along a zigzag optical path within the waveguide body, the zigzag optical path being defined by alternating reflections of the image light from the first surface and the second surface; as well as A plurality of tilting body reflectors are arranged in the waveguide body along the zigzag optical path and have tunable reflectivity for controlling the spatial distribution of the image light portions coupled out of the waveguide body by the plurality of tilting body reflectors.

2. The waveguide according to claim 1, wherein The tilting body reflector of the plurality of tilting body reflectors includes a voltage-controlled reflector having at least one of a reflectivity magnitude or a maximum reflectivity direction that is variable by applying a voltage to the voltage-controlled reflector.

3. The waveguide according to claim 1, wherein The tilting body reflectors of the plurality of tilting body reflectors are polarization selective, the waveguide further comprising a liquid crystal layer in the zigzag optical path within the waveguide body for spatially selectively controlling the polarization state of the image light propagating along the zigzag optical path, thereby controlling the spatial distribution of the image light portion; and optionally Wherein, the waveguide body comprises a stack of the following items: a substrate supporting the plurality of tilting body reflectors; Back plate electrode; the liquid crystal layer; and a pixelated electrode layer for applying a spatially varying electric field to the liquid crystal layer by applying a spatially varying electric field between the backplane and the pixelated electrode layer; Wherein, the sawtooth-shaped light path passes through the stacked body.

4. The waveguide according to claim 1, wherein: The input coupler includes at least one tilting body reflector of the plurality of tilting body reflectors.

5. The waveguide according to claim 1, wherein The plurality of tilting body reflectors comprises a two-dimensional array or a three-dimensional array of tilting body reflectors; and optionally wherein the plane of the two-dimensional array is parallel to the first surface and the second surface of the waveguide body, or The plane of the two-dimensional array is not parallel to the first surface and the second surface of the waveguide body.

6. The waveguide according to claim 1, wherein A tilting body reflector of the plurality of tilting body reflectors comprises a plurality of segments, each segment having an independently variable spatially uniform reflectivity.

7. A display device, comprising: an image projector configured to provide image light carrying an image in an angular region; as well as A waveguide for transmitting image light in a display device as claimed in any preceding claim.

8. The display device according to claim 7, wherein: Each of the plurality of tilting body mirrors includes a voltage-controlled mirror having at least one of a reflectivity magnitude or a maximum reflectivity direction that is variable by applying a voltage to the voltage-controlled mirror.

9. The display device according to claim 7, wherein: Each of the multiple inclined body reflectors is polarization selective, and the waveguide also includes a liquid crystal layer located in the zigzag optical path within the waveguide body, so as to spatially selectively control the polarization state of the image light propagating along the zigzag optical path, thereby controlling the spatial distribution of the image light portion.

10. The display device of claim 7, further comprising a controller operably coupled to the waveguide body and configured to control the reflectivity of the plurality of tilting body mirrors in a spatially selective manner based on a portion of a field of view currently displayed by the image projector; And / or the display device further includes: an eye tracking system configured to determine a position of a pupil of a user's eye at an eye zone of the display device; and A controller operably coupled to the waveguide body and the eye tracking system and configured to control the reflectivity of the plurality of tilting mirrors in a spatially selective manner based on a position of the pupil determined by the eye tracking system; and / or wherein the display device is a near-eye display device.

11. A method for transmitting image light from an image projector to an eye zone of a display device, the method comprising: coupling the image light into a waveguide body; causing the image light to propagate in the waveguide body along a zigzag optical path defined by alternating reflections of the image light from opposing first and second surfaces of the waveguide body; coupling a portion of the image light out of the waveguide body by using a plurality of tilted body reflectors disposed within the waveguide body along the zigzag optical path and having tunable reflectivity; as well as The spatial distribution of the image light portions coupled out of the waveguide body by the plurality of tilting body mirrors is controlled by tuning the reflectivity of the plurality of tilting body mirrors.

12. The method according to claim 11, wherein: Controlling the spatial distribution of the image light segments includes tuning a reflectivity of the plurality of tilted body mirrors by applying a voltage to each body mirror, each body mirror being a voltage controlled mirror.

13. The method according to claim 11, wherein: controlling the spatial distribution of the image light portion comprises controlling the polarization state of the image light propagating along the zigzag optical path in a spatially selective manner using a liquid crystal layer, the liquid crystal layer being disposed in the zigzag optical path within the waveguide body; and Wherein, each of the plurality of tilted body reflectors is polarization selective.

14. The method according to claim 11, wherein: Controlling the spatial distribution of the image light portions includes controlling the reflectivity of the plurality of tiltable mirrors in a spatially selective manner based on a portion of the field of view currently displayed by the image projector to increase the portion of the image light portions that reaches the user's eyes: the image light portion carries the portion of the field of view displayed by the image projector.

15. The method according to claim 11, wherein: Controlling the spatial distribution of the image light portions includes determining a position of a pupil of a user's eye at the eye zone of the display device; The method also includes controlling the reflectivity of the plurality of tilted mirrors in a spatially selective manner based on the determined position of the pupil of the eye to increase the portion of the image light portions that reaches the user's eye.

Images