Waveguide display with improved uniformity and reduced cross-coupling between colors

Abstract

The present application relates to a waveguide display with improved uniformity and reduced cross-coupling between colors. A waveguide display includes a plurality of diffractive optical elements (DOEs) configured to couple in image light, provide an exit pupil expanded in two directions, and couple out the image light to a user. The coupling-in DOE is configured to divide the full field of view (FOV) of the image light into a left portion and a right portion. The left FOV portion and the right FOV portion propagate laterally in a middle DOE in a left direction and a right direction, respectively, and the middle DOE includes an upper portion and a lower portion. The middle DOE provides exit pupil expansion in a horizontal direction while coupling light to an outcoupling DOE. The outcoupling DOE provides exit pupil expansion in a vertical direction and couples out image light with an expanded exit pupil for a full FOV. The middle DOE portion is configured to divert the image light back to the center of the waveguide to avoid dark areas or streaks in the portion of the outcoupling DOE.

Description

[0001] Related Applications Citations

[0002] This application is a divisional application of the invention patent application with international application number PCT / US2018 / 024699, international application date March 28, 2018, date of entry into the Chinese national phase September 29, 2019, Chinese national application number 201880022935.6, and invention name “Waveguide display with improved uniformity and reduced cross-coupling between colors”. Technical Field

[0003] The present application relates to the field of waveguide displays. Background Art

[0004] Diffractive optical elements (DOEs) are optical elements with periodic structures that are often used in applications ranging from biotechnology, material processing, sensing and testing to technical optics and optical metrology. For example, by incorporating a DOE into the light field of a laser or an emissive display, the "shape" of light can be flexibly controlled and changed according to the application requirements. Summary of the invention

[0005] A waveguide display includes a plurality of diffractive optical elements (DOEs) configured to couple in incident image light from an imager in a near-eye optical display system, provide an exit pupil expanded in two directions, and couple the image light out to a user. The coupling-in DOE is configured to divide the full field of view (FOV) of the image light into a left portion and a right portion. The left FOV portion and the right FOV portion propagate laterally in a middle DOE in a left direction and a right direction, respectively, and the middle DOE includes an upper portion and a lower portion. The middle DOE provides an exit pupil expansion in a first (e.g., horizontal) direction while coupling light to an outcoupling DOE. The outcoupling DOE provides an exit pupil expansion in a second (e.g., vertical) direction and couples image light with an expanded exit pupil for the full FOV out of the waveguide. The middle DOE portion is configured to divert the image light back to the center of the waveguide to avoid dark areas or streaks in the portion of the outcoupling DOE located below the coupling-in DOE.

[0006] The waveguide display can be further configured to selectively couple image light downward in a waveguide without cross coupling between light components in the waveguide, the waveguide comprising multiple waveguide plates to support an RGB (red, green, blue) color model. For example, the in-coupling DOE is configured as a two-sided grating with different grating vectors on each surface to in-couple incident image light and turn the in-coupled image light of the first diffraction order downward in the waveguide without coupling downward the zeroth order diffraction light that is evanescent in the waveguide. Since the light must pass through the first diffraction order that is evanescent for red light in the green waveguide plate, the red light is not coupled downward. This selective coupling reduces cross coupling of red image light into the green waveguide plate in the central portion of the FOV.

[0007] In one exemplary embodiment, the directions of the grating vectors in the top right and bottom left middle DOEs are the same or similar so that the image light can be spread toward the center of the waveguide to reduce dark areas or streaks. In another exemplary embodiment, the lower portions of the left and right middle DOEs can be combined into a single-sided grating or a two-sided grating. The direction of the grating vector of the first surface is the same or similar to the direction of the grating vector of the top right middle DOE, while the direction of the grating vector of the opposite second surface is the same or similar to the direction of the grating vector of the top middle DOE. Alternatively, the combined grating can be configured as a single-sided or two-sided crossed (i.e., two-dimensional) grating.

[0008] This summary is provided to introduce a series of concepts in a simplified form, which are further described below in the detailed description. This summary is neither intended to identify the key features or essential features of the claimed subject matter, nor is it intended to be used to help determine the scope of the claimed subject matter. In addition, the claimed subject matter is not limited to implementations that address any or all of the shortcomings noted in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A block diagram of an exemplary near-eye display system is shown;

[0010] Figure 2 shows the propagation of light in a waveguide by total internal reflection (TIR);

[0011] Figure 3 shows a view of an exemplary exit pupil expander;

[0012] Figure 4 shows a view of an exemplary exit pupil expander, wherein the exit pupil is expanded along two directions;

[0013] Figure 5 An exemplary input pupil of an exit pupil expander is shown, wherein the field of view (FOV) is described by angles in horizontal, vertical, or diagonal orientations;

[0014] Figure 6 An exemplary waveguide plate supporting propagation of light of different wavelengths as components of an RGB (red, green, blue) color model is shown;

[0015] Figure 7 shows a pictorial front view of a sealed visor that may be used as a component of a head mounted display (HMD) device;

[0016] Figure 8 A partially exploded view of the sealed visor is shown;

[0017] Fig. 9 and Fig.10 An illustrative arrangement of a diffractive optical element (DOE) configured for incoupling, exit pupil expansion, and outcoupling providing an extended field of view (FOV) is shown.

[0018] Fig.11 An edge view of a first exemplary coupled-in DOE is shown;

[0019] Fig.12 shows an edge view of a second exemplary coupled-in DOE;

[0020] Fig.13 shows an illustrative depiction of light and dark bands visible at certain angles within the FOV of a waveguide display;

[0021] Fig.14 shows an exemplary arrangement in which an intermediate DOE includes an upper portion and a lower portion that facilitate spreading of image light toward the center of a waveguide display;

[0022] Fig.15 shows an exemplary arrangement using a single-sided or double-sided coupling DOE that couples image light downward without coupling image light to the left for certain angles within the FOV;

[0023] Fig.16 An exemplary arrangement using a double-sided coupling-in DOE is shown, which enables downward coupling of image light but without cross coupling between color components;

[0024] Fig.17 shows an outline of a portion of an exemplary diffraction grating having a straight grating;

[0025] Fig.18 shows an asymmetric profile of a portion of an exemplary diffraction grating having an asymmetric grating or a tilted grating;

[0026] Figures 19 to 22 Various exemplary two-dimensional diffraction gratings are shown;

[0027] Fig.23 An exemplary method is shown;

[0028] Fig.24 is a pictorial view of an illustrative example of a virtual reality or mixed reality HMD device;

[0029] Fig.25 A block diagram showing an illustrative example of a virtual reality or mixed reality HMD device; and

[0030] Fig.26 A block diagram of an illustrative electronic device incorporating an exit pupil expander is shown.

[0031] In the drawings, like reference numerals refer to like elements. Unless otherwise noted, elements are not drawn to scale. DETAILED DESCRIPTION

[0032] Figure 1 A block diagram of an exemplary near-eye display system 100 is shown that can incorporate a combination of diffractive optical elements (DOEs) that provide incoupling of incident light into a waveguide, exit pupil expansion in two directions, and outcoupling of light out of the waveguide. Near-eye display systems are commonly used in head mounted display (HMD) devices, such as in industrial, commercial, and consumer applications. Other devices and systems may also use near-eye systems, as described below. Near-eye display system 100 is an example that is used to provide context and illustrate various features and aspects of the present waveguide display with increased uniformity and reduced cross coupling between colors.

[0033] The system 100 may include one or more imagers (representatively indicated by reference numeral 105) that work with an optical system 110 to deliver an image to a user's eye 115 as a virtual display. For example, the imager 105 may include an RGB (red, green, blue) light emitting diode (LED), an LCOS (liquid crystal on silicon) device, an OLED (organic light emitting diode) array, a MEMS (micro-electromechanical system) device, or any other suitable display or micro-display operating in transmission, reflection, or emission. The imager 105 may also include mirrors and other components that enable the virtual display to be constructed and provide one or more input beams to the optical system. The optical system 110 may generally include a magnifying optical device 120, a pupil forming optical device 125, and one or more waveguides 130. In some implementations, the imager 105 may include or incorporate an illumination unit and / or a light engine (not shown), which may be configured to provide illumination within a range of wavelengths and intensities.

[0034] In a near-eye display system, the imager does not actually shine an image onto a surface, such as a glass lens, to produce a visual display for the user. This is not feasible because the human eye cannot focus on something so close. Instead of producing a visible image on a surface, the near-eye display system 100 uses pupil forming optics 125 to form a pupil, and the eye 115 acts as the last element in the optical chain and converts the light from the pupil into an image on the retina of the eye as a virtual display.

[0035] Waveguide 130 facilitates light transmission between the imager and the eye. One or more waveguides may be used in near-eye display systems because they are transparent and because they are generally small and lightweight (which is desirable in applications such as HMD devices, where size and weight are generally minimized for performance and user comfort reasons). For example, waveguide 130 may enable imager 105 to be positioned out of the way, such as at the side of the user's head or near the forehead, leaving only a relatively small, light, and transparent waveguide optical element in front of the eye. In one implementation, waveguide 130 operates using the principle of total internal reflection, such as Figure 2 As shown, light can be coupled between various optical elements in system 100.

[0036] Figure 3 A view of an exemplary exit pupil expander (EPE) 305 is shown. The EPE 305 receives an input beam from the imager 105 as an entrance pupil through optics 120 (e.g., magnification and / or collimation optics) to produce one or more output beams having an exit pupil expanded in one or two directions relative to the exit pupil of the imager (in general, the input may include more than one beam that may be generated by a single source). The expanded exit pupil generally facilitates adequate resizing of the virtual display to meet various design requirements of a given optical system, such as image resolution, field of view, etc., while enabling the imager and associated components to be relatively light and compact.

[0037] In this illustrative example, the EPE 305 is configured to support binocular operation for both the left eye and the right eye, which may support stereoscopic viewing. For clarity of illustration, Figure 3 Components that can be used for stereoscopic operation, such as scanning mirrors, lenses, filters, beam splitters, MEMS devices, etc., are not shown. EPE 305 utilizes two outcoupling gratings 310 L and 310 R, which are supported on the waveguide 130 and the central coupling grating 340. Multiple DOEs can be used to configure the coupling grating and the outcoupling grating, as described below. Although the EPE 305 is depicted as having a planar configuration, other shapes can also be utilized, including, for example, curved or partially spherical shapes, in which case the gratings disposed thereon are non-coplanar.

[0038] like Figure 4 As shown, the EPE 305 can be configured to provide an exit pupil that expands in two directions (i.e., along each of the first coordinate axis and the second coordinate axis). As shown, the exit pupil expands in both the vertical direction and the horizontal direction. It will be appreciated that, for ease of description, the terms "left", "right", "direction", "horizontal", and "vertical" are primarily used to establish relative orientations in the illustrative examples shown and described herein. These terms may be intuitive for use scenarios in which the user of the near-eye display device is upright and facing forward, but less intuitive for other use scenarios. The listed terms should not be interpreted as limiting the scope of the configurations of the near-eye display features utilized in the present waveguide display (and the use scenarios therein). The entrance pupil of the EPE 305 at the coupling-in grating 340 is typically described in terms of FOV (e.g., using a horizontal FOV, a vertical FOV, or a diagonal FOV), such as Figure 5 shown.

[0039] The present waveguide display can be arranged with color capabilities using an RGB (red, green, blue) color model. Thus, a waveguide display can be configured using three layers 605, 610, and 615 that use separate waveguide plates to propagate each of the red image light, the green image light, and the blue image light. In an alternative arrangement, two layers can be utilized, with red light propagating in one waveguide plate and mixed blue and green light propagating in another waveguide plate.

[0040] Now, turning to the various implementation details of this waveguide display, Figure 7 An illustrative example of a visor 700 is shown that incorporates an internal near-eye display system for a head mounted display (HMD) device 705 worn by a user 715. In this example, the visor 700 is sealed to protect the internal near-eye display system. The visor 700 typically interfaces with other components (not shown) of the HMD device, such as a head mounting / retention system and other subsystems including sensors, power management, controllers, etc., such as in conjunction with Fig.24 and Fig.25 Suitable interface elements (not shown) including snaps, bosses, screws, and other fasteners may also be incorporated into the visor 700 .

[0041] The visor 700 includes front and rear see-through screens (704 and 706, respectively) that may be molded using transparent materials to facilitate unobstructed vision of the optical display and surrounding real-world environment. Treatments such as tinting, mirroring, anti-reflective, anti-fog, and other coatings may be applied to the front and rear screens, and a variety of colors and finishes may also be utilized. The front and rear screens are attached to a frame 805 that is mounted on a Figure 8 is shown in the exploded view in FIG.

[0042] When the HMD device is used in operation and during normal handling for cleaning, etc., the sealed visor 700 can physically protect sensitive internal components, including the near-eye display system 802 ( Figure 8 ). The near-eye display system 802 includes a left optical display 810 and a right optical display 815, which provide virtual world images to the user's left eye and right eye, respectively. The visor 700 can also protect the near-eye display system 802 from environmental elements and damage caused by the HMD device being dropped or bumped, hit, etc.

[0043] like Figure 8 As shown, the rear screen 706 is configured in an ergonomically suitable form to interface with the user's nose and may include nose pads and / or other comfort features (e.g., added thereto as a discrete component and / or molded therein). In some cases, the sealed visor 700 may also incorporate a certain level of optical diopter curvature (i.e., eye prescription) within the molded screen.

[0044] Fig. 9 An exemplary optical display 900 is shown having multiple DOEs that can be used with or incorporated as part of a waveguide 930 to provide incoupling, expansion of the exit pupil in two directions, and outcoupling. The optical display 900 can be used to be included in a near-eye display system 802 ( Figure 8 ) in an exit pupil expander to provide a virtual world image to one of the user's eyes. Each DOE is an optical element including a periodic structure that can modulate various properties of light in a periodic pattern, such as the direction of the optical axis, the optical path length, etc.

[0045] At the in-coupling DOE 905, the FOV is divided into two parts - a left part and a right part. Each of the left and right parts uses a FOV that can propagate within the DOE without leakage. The left and right parts are then optically stitched together at the out-coupling DOE 920 to provide an extended FOV for the virtual image coupled out from the display 900 to the user's eyes. Thus, in one non-limiting illustrative example, the diagonal FOV of each of the left and right parts can be 30 degrees, while the extended FOV of the optically stitched image is 60 degrees.

[0046] The left middle DOE 915 extends from the center of the waveguide 930 to the left edge of the waveguide 930. The right middle DOE 910 extends from the center of the waveguide 930 to the right edge of the waveguide 930. Each of the left middle DOE and the right middle DOE expands the exit pupil in a first direction along the first coordinate axis. Both the left middle DOE and the right middle DOE can be set on the same side of the waveguide. In an alternative implementation, the left middle DOE and the right middle DOE can be set on opposite sides of the waveguide. In some implementations, the left middle DOE and the right middle DOE can also overlap. As shown, the left middle DOE 915 and the right middle DOE 910 couple light between the coupling-in DOE 905 and the single coupling-out DOE 920, which is positioned in the center toward the bottom portion of the waveguide 930. The coupling-out DOE 920 expands the exit pupil in a second direction along the second coordinate axis and couples light out of the waveguide and into the user's eyes.

[0047] like Fig.10 As shown, portions of the FOV propagate to the left and right (as indicated by reference numerals 1005 and 1010, respectively), and the full FOV propagates downward (as indicated by reference numeral 1015). For example, the in-coupling DOE 905 may include linear grating features on one side that couple incident image light to the left and right, and linear grating features on the opposite side that couple light downward. Alternatively, crossed (i.e., two-dimensional) grating features may be used on one or both surfaces of the in-coupling DOE 905 to couple light not only to the sides but also downward.

[0048] although Fig.10The approach shown in works satisfactorily for a single waveguide plate, but when two or three waveguide plates are utilized to support an RGB color model, fairly significant cross-coupling between colors can occur, which can degrade image quality. Specifically, parameters describing display uniformity and MTF (modulation transfer function) are typically suboptimal. The root cause of the cross-coupling is direct down-coupling through the coupling-in DOE, where red light is cross-coupled into the waveguide plate for green light to cause MTF degradation. Most of the red light, especially around the center of the FOV, has evanescent diffraction orders when coupled to the side, but is propagating when coupled down. Thus, the present waveguide display is configured to avoid direct down-coupling of image light.

[0049] The present waveguide display can Fig.11 and Fig.12 The grating profile shown is used for coupling into a DOE. Fig.11 An edge view of a single-sided coupling-in DOE 1105 is shown, which is divided into two parts 1110 and 1120, which have tilted grating features tilted in opposite directions. This "split tilt" configuration generally provides enhanced coupling efficiency when coupling light toward the lateral edges of the coupling-in DOE (as representatively indicated by arrows 1130 and 1135, where the arrow width indicates relative intensity). Fig.12 Shown are separate tilted grating features 1210 and 1220 on either side of a two-sided incoupling DOE 1205. Other grating features may be used in alternative implementations for incoupling, including, for example, index modulated gratings, index switched gratings, or polarization gratings.

[0050] Because the in-coupling DOE is configured to avoid coupling the image light directly downward, the intermediate DOE is configured to allow the light to spread back toward the central region of the waveguide. Fig.13 As shown, in the outcoupling DOE 920 below the incoupling DOE 905, banded stripes and / or dark stripes (indicated by reference numeral 1305) may appear where there is no light.

[0051] Fig.14A waveguide display 1400 is shown using an arrangement of multiple DOEs on a waveguide 1430. An incoupling DOE 1405, which may include one or two separate tilted gratings, is configured to couple image light from an imager laterally to the left and right to a corresponding intermediate DOE. The intermediate DOE includes two components or portions - an upper portion adjacent to the incoupling DOE, and a lower portion adjacent to a single outcoupling DOE 1420. Thus, as shown, four intermediate DOEs are utilized - an upper right intermediate DOE 1410, a lower right intermediate DOE 1416, an upper left intermediate DOE 1415, and a lower left intermediate DOE 1414. The intermediate DOEs are configured to provide an exit pupil that expands in a first direction to the left and right portions of the FOV of the image light. The outcoupling DOE 1420 provides an exit pupil expansion in a second direction and couples the image light out to the user's eyes across the full FOV.

[0052] In this illustrative example, the direction of the grating vector of the lower left middle DOE 1414 is the same or nearly the same as the grating vector of the upper right middle DOE 1410. As shown by the arrow (representatively indicated by reference numeral 1450), this alignment of the grating vectors enables light to be guided back to the center of the waveguide 1430. In an alternative implementation, the lower left middle DOE and the lower right middle DOE can be combined and configured as a two-sided grating with grating features on both sides. The direction of the grating vector of one surface is the same or similar to the direction of the grating vector of the upper right middle DOE 1410. The direction of the grating vector of the opposite surface is the same or similar to the direction of the grating vector of the upper left middle DOE 1415. In another alternative implementation, the combined lower left middle DOE and lower right middle DOE can be configured as a one-sided or two-sided cross grating.

[0053] The waveguide display 1400 with left and right, top and bottom center DOEs can provide improved display uniformity by reducing cross coupling (e.g., red light entering a green waveguide plate). However, some angles within the FOV may be evanescent within the waveguide, which may cause dark areas at some eye positions. Although some improvement can be achieved by increasing the distance between the coupling-in DOE and the coupling-out DOE, this may be suboptimal in some implementations due to the increased size of the waveguide plates. For example, if Fig.15 As shown, when using a single-sided or double-sided coupling DOE 1505, the incident image light is not coupled to the left because some FOV angles are evanescent within the waveguide 1530.

[0054] like Fig.16As shown, the lack of coupling to the left can be addressed by using an in-coupling DOE 1605 that includes linear grating features in a parallel configuration on a first surface of the two-sided in-coupling DOE 1605, and linear grating features in a herringbone configuration on a second surface on the opposite side. The directions of the grating vectors are different for the first and second surfaces of the in-coupling DOE. The first (e.g., front) surface couples the incident image light, while the second (e.g., back) surface turns the in-coupled light at the first diffraction order downward, but since the zeroth order diffraction waves are evanescent, they are not coupled downward. Since the light must pass through the first diffraction order, this configuration enables coupling of light downward without cross-coupling red light into the green waveguide plate because red light is evanescent.

[0055] The grating features used in the DOE of the present waveguide display with increased uniformity and reduced cross-coupling between colors can take various suitable forms. For example, Fig.17 1 shows an outline of straight (ie, non-tilted) grating features 1700 (referred to as grating bars, grating lines, or simply "gratings") formed in a substrate 1705. In contrast, Fig.18 A grating feature 1800 formed in a substrate 1805 having an asymmetric profile is shown. That is, the grating can be tilted relative to the plane of the waveguide (i.e., non-orthogonal). In implementations where the waveguide is non-planar, the grating can be tilted relative to the direction of light propagation in the waveguide. Asymmetric grating profiles can also be implemented using blazed gratings or echelon gratings, where grooves are formed to produce grating features with an asymmetric triangular or sawtooth profile. Fig.17 and Fig.18 In , the grating period is denoted by d, the grating height is denoted by h, the stripe width is denoted by c, and the filling factor is denoted by f, where f = c / d. Fig.18 The tilted grating in the image can be represented by the tilt angle α 1 and α 2 describe.

[0056] Figures 19 to 22 Various exemplary two-dimensional (2D) diffraction gratings that may be used in some implementations of an in-coupling DOE are shown. 2D gratings may also be used to impart polarization sensitivity to a DOE (eg, an in-coupling DOE and / or an intermediate DOE). Figures 19 to 22The 2D gratings in are intended to be illustrative rather than limiting, and it is contemplated that variations from the 2D gratings shown may also be utilized. In some cases, the gratings may include symmetrical features and / or asymmetrical features, the asymmetrical features including tilted gratings (i.e., gratings having walls that are non-orthogonal to the plane of the waveguide according to one or more predetermined angles) and blazed gratings (i.e., gratings having asymmetrical triangular or sawtooth profiles). Various suitable surface relief profiles, fill factors, grating periods, and grating dimensions may also be utilized, depending on the requirements of a particular implementation.

[0057] Fig.19 A 2D grating 1905 is shown, which includes quadrilateral elements protruding from a substrate. The quadrilateral elements can also be configured to be asymmetric, such as tilted or flared. Non-quadrilateral three-dimensional geometries (both symmetric and asymmetric) can also be used for 2D gratings, including, for example, cylindrical elements, polygonal elements, elliptical elements, etc. For example, Fig. 20 A 2D grating 2005 comprising pyramid elements is shown, and Fig.21 A 2D grating 2105 is shown, which includes elements with a blazed profile in each of the x and z directions. The grating may also have elements with curved profiles, such as Fig. 22 An exemplary 2D grating 2205 is shown in FIG.

[0058] Fig.23 2300. Unless otherwise specified, the methods or steps shown in the flowcharts and described in the accompanying text are not limited to a particular order or sequence. In addition, depending on the requirements of such implementation, certain methods or steps thereof may occur or be performed simultaneously, and not all methods or steps must be performed in a given implementation, and some methods or steps may be optionally utilized.

[0059] At step 2305, image light from the imager is received at the incoupling DOE as an entrance pupil. At step 2310, the FOV of the received image light is divided into a left FOV portion and a right FOV portion at the incoupling DOE. The left FOV portion and the right FOV portion of the received image light are diverted to the corresponding left middle DOE and right middle DOE by the incoupling DOE.

[0060] At step 2315, the left FOV portion of the coupled-in image light propagates in the left middle DOE such that the exit pupil of the left FOV portion expands along the horizontal axis and the light is diffracted downward along the vertical axis to the out-coupling DOE. At this step, the red component of the image light is evanescent and therefore does not propagate along the vertical axis in the left middle DOE. At step 2320, the right FOV portion of the coupled-in image light propagates in the right middle DOE such that the exit pupil of the right FOV portion expands along the horizontal axis and the light is diffracted downward along the vertical axis to the out-coupling DOE.

[0061] At step 2325, the exit pupils of the left FOV portion and the right FOV portion of the propagated image light are expanded along the vertical axis in the out-coupling DOE. At step 2330, the image light for the left FOV portion and the right FOV portion is output from the out-coupling DOE. The output image light has a pupil that is expanded along the horizontal axis and the vertical axis relative to the entrance pupil. Compared to conventional optical displays, the out-coupling DOE operates to optically stitch the left FOV portion and the right FOV portion together to provide an extended full FOV (i.e., having a larger angular FOV).

[0062] Fig.24 One specific illustrative example of a see-through mixed reality or virtual reality HMD device 2400 is shown, and Fig.25 A functional block diagram of device 2400 is shown. HMD device 2400 includes one or more lenses 2402, which form part of a see-through display subsystem 2404, so that images can be displayed using lenses 2402 (e.g., using projection onto lenses 2402, one or more waveguide systems (such as near-eye display systems) incorporated into lenses 2402, and / or in any other suitable manner). HMD device 2400 further includes one or more outward-facing image sensors 2406, which are configured to acquire images of background scenes and / or physical environments that the user is viewing; and HMD device 2400 may include one or more microphones 2408, which are configured to detect sounds such as voice commands from the user. Outward-facing image sensors 2406 may include one or more depth sensors and / or one or more two-dimensional image sensors. As described above, in an alternative arrangement, instead of incorporating a see-through display subsystem, a mixed reality or virtual reality display system may display mixed reality images or virtual reality images through a viewfinder mode for outward-facing image sensors.

[0063] The HMD device 2400 may further include a gaze detection subsystem 2410, which, as described above, is configured to detect the gaze direction or direction or position of the focus of each eye of the user. The gaze detection subsystem 2410 may be configured to determine the gaze direction of each eye of the user in any suitable manner. For example, in the illustrative example shown, the gaze detection subsystem 2410 includes: one or more flicker sources 2412, such as infrared light sources, which are configured to cause light flickers to be reflected from each eyeball of the user; and one or more image sensors 2414, such as inward-facing sensors, which are configured to capture images of each eyeball of the user. As determined based on image data collected using (multiple) image sensors 2414, changes in flicker from the user's eyeballs and / or changes in the user's pupil position can be used to determine the gaze direction.

[0064] In addition, the location where the gaze line projected from the user's eye intersects the external display can be used to determine the object the user is looking at (e.g., a displayed virtual object and / or a real background object). The gaze detection subsystem 2410 can have any suitable number and arrangement of light sources and image sensors. In some implementations, the gaze detection subsystem 2410 can be omitted.

[0065] The HMD device 2400 may also include additional sensors. For example, the HMD device 2400 may include a global positioning system (GPS) subsystem 2416 to allow determination of the location of the HMD device 2400. This may be helpful in identifying real-world objects that may be located in the user's immediate physical environment, such as buildings, etc.

[0066] The HMD device 2400 may further include one or more motion sensors 2418 (e.g., inertial, multi-axis gyroscopes, or accelerometers) to detect movement and position / orientation / posture of the user's head when the user is wearing the system as part of a mixed reality or virtual reality HMD device. The motion data (possibly together with eye-tracking glint data and outward-facing image data) may be used for gaze detection, and for image stabilization to help correct blur in images from the outward-facing image sensor(s) 2406. The use of motion data may allow tracking of changes in gaze position even if the image data from the outward-facing image sensor(s) 2406 cannot be resolved.

[0067] In addition, the motion sensor 2418, as well as the microphone(s) 2408 and the gaze detection subsystem 2410, may also be employed as user input devices, so that the user may interact with the HMD device 2400 via gestures of the eyes, neck, and / or head, and in some cases via verbal commands. Fig.24 and Fig.25 The sensors illustrated in and described in the accompanying text are included for purposes of example and are not intended to be limiting in any way, as any other suitable sensors and / or combinations of sensors may be utilized to meet the needs of a particular implementation. For example, biometric sensors (e.g., for detecting heart and respiratory rate, blood pressure, brain activity, body temperature, etc.) or environmental sensors (e.g., for detecting temperature, humidity, altitude, UV (ultraviolet) light levels, etc.) may be utilized in some implementations.

[0068] The HMD device 2400 may further include a controller 2420, such as one or more processors, having a data storage subsystem 2424 and a logic subsystem 2422 that communicate with sensors, gaze detection subsystem 2410, display subsystem 2404, and / or other components via a communication subsystem 2426. The communication subsystem 2426 may also facilitate the display system to operate in conjunction with remotely located resources such as processing, storage, power, data, and services. That is, in some implementations, the HMD device may operate as part of a system that may distribute resources and capabilities among different components and subsystems.

[0069] Storage subsystem 2424 may include instructions stored thereon that may be executed by logic subsystem 2422, for example, to receive and interpret input from sensors, identify the position and movement of a user, identify real objects using surface reconstruction and other techniques, and dim / fade the display based on the distance to the object so that the object can be seen by the user, among other tasks.

[0070] The HMD device 2400 is configured with one or more audio transducers 2428 (e.g., speakers, headphones, etc.) so that audio can be used as part of a mixed reality or virtual reality experience. The power management subsystem 2430 may include one or more batteries 2432 and / or a protection circuit module (PCM) and an associated charger interface 2434 and / or a remote power interface for supplying power to components in the HMD device 2400.

[0071] It can be appreciated that the HMD device 2400 is described for purposes of example and is not intended to be limiting. It can be further understood that the display device can include additional and / or alternative sensors, cameras, microphones, input devices, output devices, etc., other than those shown, without departing from the scope of the present arrangement. Additionally, the physical configuration of the HMD device and its various sensors and subcomponents can take a variety of different forms without departing from the scope of the present arrangement.

[0072] like Fig.26As shown, a near-eye display system with a waveguide display having increased uniformity and reduced cross-coupling between colors can be used in a mobile or portable electronic device 2600, such as a mobile phone, a smart phone, a personal digital assistant (PDA), a communicator, a portable Internet device, a handheld computer, a digital video or still camera, a wearable computer, a computer gaming device, a dedicated bring-to-the-eye product for viewing, or other portable electronic device. As shown, the portable device 2600 includes a housing 2605 to house a communication module 2610 for receiving information from and sending information to an external device or remote system or service (not shown).

[0073] The portable device 2600 may also include an image processor 2615 and a virtual display system 2620, the image processor 2615 using one or more processors to process the received and transmitted information, and the virtual display system 2620 for supporting the viewing of images. The virtual display system 2620 may include a micro display or imager 2625 and an optical engine 2630. The image processor 2615 may be operably connected to the optical engine 2630 to provide image data such as video data to the imager 2625 to display an image on the imager 2625. The EPE 2635 may be optically linked to the optical engine 2630. The EPE may utilize a waveguide display, as described herein, the uniformity of which is increased and the cross-coupling between colors is reduced.

[0074] Waveguide displays with increased uniformity and reduced cross-coupling between colors can also be used in non-portable devices such as gaming devices, multimedia consoles, personal computers, vending machines, smart devices, Internet-connected devices, and household appliances (such as ovens, microwave ovens and other appliances), as well as other non-portable devices.

[0075] Various exemplary embodiments of the present waveguide display having increased uniformity and reduced cross-coupling between colors are now presented by way of illustration and not as an exhaustive list of all embodiments. One example includes a near-eye display system configured to provide image light within a field of view (FOV) having a first axis and a second axis from an imager to an eye of a user of the near-eye display system, the near-eye display system comprising: a substrate of optical material configured as a waveguide for guiding the image light in the near-eye display system; an incoupling diffractive optical element (DOE) disposed on the substrate and configured to couple image light over the entirety of the FOV into the waveguide; a left middle DOE disposed on the substrate and optically coupled to the incoupling DOE to receive image light for a left portion of the FOV, wherein the left middle DOE is configured to expand the received image light along the first axis; a right middle DOE disposed on the substrate and optically coupled to the incoupling DOE to receive image light for a right portion of the FOV, wherein the right middle DOE is configured to The invention relates to a waveguide comprising a first substrate and a second substrate, wherein the first substrate is provided with a coupling-in DOE and a coupling-out DOE, wherein the coupling-out DOE is configured to expand the received image light along a first axis; and an outcoupling DOE, which is disposed on a substrate and is configured to receive the image light of the left and right parts of the FOV from the left middle DOE and the right middle DOE, respectively, the coupling-out DOE being configured for pupil expansion of the image light of each part of the left and right parts of the FOV along a second axis, and further configured to couple the combined left and right parts of the image light over the FOV as a whole from the waveguide; wherein the left middle DOE includes a top portion and a bottom portion, the top portion is disposed in the waveguide adjacent to the coupling-in DOE, and the bottom portion is disposed in the waveguide adjacent to the coupling-out DOE, and wherein the right middle DOE includes a top portion and a bottom portion, the top portion is disposed in the waveguide adjacent to the coupling-in DOE, and the bottom portion is disposed in the waveguide adjacent to the coupling-out DOE.

[0076] In another example, the left middle DOE and the right middle DOE are each connected to the coupling-in DOE interface around a corresponding portion of the periphery of the coupling-in DOE. In another example, the coupling-in DOE is located centered between the left middle DOE and the right middle DOE. In another example, the upper left middle DOE extends laterally from the coupling-in DOE, and the upper right middle DOE extends laterally from the coupling-in DOE. In another example, the substrate is planar. In another example, the left middle DOE and the right middle DOE are disposed on opposite sides of the substrate. In another example, the coupling-in DOE includes a front side and a rear side, the front side and the rear side are disposed on opposite sides of the substrate, and the front side and the rear side have corresponding grating vectors with different directions.

[0077] A further example includes an electronic device configured to display image light of a virtual image in a full field of view (FOV), the full field of view including a first partial FOV and a second partial FOV, the full FOV having a horizontal direction and a vertical direction, the electronic device including: a waveguide, a plurality of diffractive optical elements (DOEs) being arranged on the waveguide, the waveguide including a plurality of plates, the plurality of plates being configured to guide red color components, green color components, and blue color components of the image light, respectively; a coupling-in DOE, which is arranged on the waveguide and is configured to have grating features on a first portion of the coupling-in DOE, and grating features on a second portion of the coupling-in DOE, the grating vectors of the grating features on the first portion are different from the grating features on the second portion, the grating features on the first portion are configured to couple the image light into the waveguide, and the grating features on the second portion are configured to deflect the coupled image light in the vertical direction while minimizing cross-coupling between the color components; a first intermediate DOE, which is configured to expand the first partial FOV in the horizontal direction; and a second intermediate DOE, which is configured to expand the second partial FOV in the horizontal direction.

[0078] In another example, the first portion includes a first surface and the second portion includes a second surface, and the coupling-in DOE is configured as a two-sided DOE, and the first surface and the second surface are located on opposite sides. In another example, the grating features on the first surface or the second surface of the coupling-in DOE are arranged in a separated tilted configuration. In another example, the grating features on the first surface or the second surface of the coupling-in DOE are arranged as one of the following: a refractive index modulated grating, a refractive index switchable grating, or a polarization sensitive grating. In another example, the electronic device further includes a coupling-out DOE, which is disposed on the waveguide and is configured to expand the image light of each of the first partial FOV and the second partial FOV in the vertical direction, and is further configured to couple the image light out of the waveguide with an exit pupil expanded in the horizontal and vertical directions across the full FOV. In another example, the first intermediate DOE includes a first portion disposed in the waveguide adjacent to the in-coupling DOE and a second portion disposed in the waveguide adjacent to the out-coupling DOE, and the second intermediate DOE includes a first portion disposed in the waveguide adjacent to the in-coupling DOE and a second portion disposed in the waveguide adjacent to the out-coupling DOE. In another example, the first portion of the first intermediate DOE and the second portion of the second intermediate DOE share a common grating vector direction.

[0079] Further examples include a method of operating a waveguide display having left, right, top and bottom boundaries and having a vertical axis and a horizontal axis, the method comprising: receiving image light having an entrance pupil within a full field of view (FOV) at an in-coupling diffractive optical element (DOE) disposed in the waveguide, the image light having a red component, a green component and a blue component; using the in-coupling DOE, dividing the FOV of the received image light into a left FOV portion and a right FOV portion; using the in-coupling DOE, horizontally turning the left FOV portion of the in-coupling image light to the left and horizontally turning the right FOV portion of the in-coupling image light to the right; propagating the left FOV portion of the in-coupling image light in a left middle DOE disposed in the waveguide, wherein The exit pupil of the middle left FOV portion is expanded along the horizontal axis and diffracted downward along the vertical axis to the outcoupling DOE, wherein the red component of the image light is evanescent and does not propagate along the vertical axis; the right FOV portion of the coupled-in image light is propagated in the right middle DOE set in the waveguide, wherein the exit pupil of the right FOV portion is expanded along the horizontal axis and diffracted downward along the vertical axis to the outcoupling DOE; in the outcoupling DOE set in the waveguide, the exit pupils of the left FOV portion and the right FOV portion of the propagated image light are expanded along the vertical axis; and using the outcoupling DOE, the image light of the left FOV portion and the right FOV portion having the exit pupil expanded along the horizontal and vertical axes relative to the entrance pupil at the coupling-in DOE is output.

[0080] In another example, the image light propagates in opposite directions in the left middle DOE and the right middle DOE, or the image light propagates in the left middle DOE and the right middle DOE with orthogonal polarization states. In another example, the incoupling DOE is centrally disposed on the exit pupil expander, and the left middle DOE and the right middle DOE extend laterally from the incoupling DOE on the exit pupil. In another example, the method further includes stitching the left FOV portion and the right FOV portion together to provide a full FOV at the outcoupling DOE. In another example, the stitched FOV portion is in one of a symmetric configuration or an asymmetric configuration in the full FOV. In another example, the separating includes selecting the FOV propagation based on the evanescent diffraction order.

[0081] Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. An electronic device configured to display image light of a virtual image on a display system, the display system having a horizontal direction and a vertical direction, the displayed virtual image having a full-angle field of view FOV, the full-angle FOV including a first partial angle FOV and a second partial angle FOV, the full-angle FOV having a horizontal direction and a vertical direction, the electronic device comprising: a waveguide on which a plurality of diffractive optical elements (DOEs) are disposed, the waveguide comprising a plurality of plates configured to guide a red color component, a green color component, and a blue color component of the image light, respectively; a coupling-in DOE, the coupling-in DOE being disposed on the waveguide and being configured with grating features on a first portion of the coupling-in DOE and grating features on a second portion of the coupling-in DOE, the grating features on the first portion having a different grating vector from the grating features on the second portion, the grating features on the first portion being configured to couple image light into the waveguide, and the grating features on the second portion being configured to turn the coupled-in image light of a first diffraction order for the full-angular FOV of the displayed virtual image in the vertical direction without turning the coupled-in image light of a zero-order diffraction for the full-angular FOV of the displayed virtual image in the vertical direction, so as to minimize cross-coupling between the color components, the grating features of the coupling-in DOE being further configured to divide the full-angular FOV of the displayed virtual image into the first partial angular FOV and the second partial angular FOV; a first intermediate DOE configured to expand the first partial angular FOV in the horizontal direction; as well as a second intermediate DOE configured to expand the second partial angular FOV in the horizontal direction, The first partial angular FOV and the second partial angular FOV are angular portions of the full-angular FOV of the displayed virtual image.

2. The electronic device of claim 1 , wherein the first portion of the coupling-in DOE comprises a first surface, and the second portion of the coupling-in DOE comprises a second surface, and the coupling-in DOE is configured as a two-sided DOE, and the first surface and the second surface are located on opposite sides.

3. An electronic device according to claim 2, wherein the grating features on the first surface or the second surface of the coupling-in DOE are arranged in a split tilt configuration, and the split tilt configuration includes a grating feature on the first surface or the second surface divided into two parts, which have grating features tilted in opposite directions.

4. The electronic device of claim 2, wherein the grating features on the first surface of the coupled-in DOE are linear and in a parallel configuration.

5. The electronic device of claim 2, wherein the grating features on the second surface of the coupled-in DOE are linear and in a herringbone configuration.

6. The electronic device of claim 2, wherein the grating features on the first surface or the second surface of the coupling-into DOE are arranged as one of: a refractive index modulated grating, a refractive index switchable grating, or a polarization sensitive grating. 7 . The electronic device of claim 5 , wherein the first surface is configured to couple light incident on the in-coupling DOE into the waveguide.

8. The electronic device according to claim 3, further comprising: an out-coupling DOE disposed on the waveguide and configured to expand the image light of each of the first partial angular FOV and the second partial angular FOV in the vertical direction, and further configured to couple the image light out of the waveguide with an exit pupil expanded in the horizontal direction and the vertical direction across the full-angle FOV relative to the in-coupled image light. 9 . The electronic device of claim 8 , wherein the second surface is configured to optically redirect incoupled light of a first diffraction order toward the outcoupling DOE.

10. The electronic device of claim 8, wherein the first intermediate DOE comprises a first portion disposed in the waveguide adjacent to the in-coupling DOE, and a second portion disposed in the waveguide adjacent to the out-coupling DOE, and the second intermediate DOE comprises a first portion disposed in the waveguide adjacent to the in-coupling DOE, and a second portion disposed in the waveguide adjacent to the out-coupling DOE.

11. The electronic device of claim 10, wherein the first portion of the first intermediate DOE and the second portion of the second intermediate DOE share a common grating vector direction.

12. The electronic device of claim 10, wherein the first portion of the second intermediate DOE and the second portion of the first intermediate DOE share a common grating vector direction.

13. The electronic device of claim 10, wherein a second portion of each of the first intermediate DOE and the second intermediate DOE is adjacent to both the coupling-in DOE and the coupling-out DOE.

14. The electronic device according to claim 1 further includes a second coupling DOE and a third coupling DOE, wherein the coupling DOE, the second coupling DOE and the third coupling DOE are arranged on corresponding boards among the multiple boards in the waveguide, and each of the coupling DOE, the second coupling DOE and the third coupling DOE is configured to couple the red color component, the green color component and the blue color component into the corresponding board in the waveguide. 15 . The electronic device of claim 1 , wherein the first intermediate DOE and the second intermediate DOE are disposed on opposite sides of the waveguide, respectively.

16. The electronic device of claim 1, wherein the coupling-in DOE is located at a center of a waveguide between the first intermediate DOE and the second intermediate DOE.

17. The electronic device of claim 1, further comprising an imager configured to generate the red color component, the green color component, and the blue color component of the image light, wherein the image light is associated with one or more virtual reality or mixed reality images.

18. The electronic device of claim 17, wherein the imager comprises a microdisplay using one of a light emitting diode (LED), a liquid crystal on silicon (LCOS) device, an organic light emitting diode (OLED) array, or a micro electromechanical system (MEMS) device.

19. The electronic device according to claim 1, which is incorporated into a head mounted display (HMD) device.

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