Waveguide-based display with colored layer

Abstract

An electronic device may include a first biasing lens that transmits world light to an output coupler on a waveguide. The output coupler may transmit the world light while coupling image light out of the waveguide. A second biasing lens may transmit the world light and the image light to an eye-fit region. The colored layer may transmit the world light toward the output coupler. The colored layer may be planar and laminated onto a planar surface of the first offset lens or another lens, may be separated from the first offset lens by an air gap, may be non-parallel with respect to the waveguide, and / or may be curved and separated from the first offset lens and the waveguide by an air gap. When planar, the colored layer may be provided with spacers between the substrates or between the colored layer and the waveguide to maximize parallelism.

Description

[0001] This application claims priority to U.S. Patent Application No. 18 / 489,662, filed on October 18, 2023, and U.S. Provisional Patent Application No. 63 / 425,547, filed on November 15, 2022, the entire disclosures of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION

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

[0003] An electronic device may include a display that provides an image near a user's eye. Such electronic devices often include virtual reality or augmented reality head-mounted headsets having a display with optical elements that allow a user to view the display. If not carefully designed, the components used to display an image may be bulky and may not exhibit a desired level of optical performance. SUMMARY OF THE INVENTION

[0004] An electronic device may have a display system for providing image light to an eye comfort zone. The display system may include a waveguide. A projector may generate image light that includes virtual objects. An input coupler may couple the image light into the waveguide. An output coupler may couple the image light out of the waveguide and toward the eye comfort zone. The eye comfort zone may have a field of view (FOV). The output coupler may also transfer world light from an external object into the eye comfort zone within the FOV.

[0005] A first biasing lens may transmit world light to the output coupler on a corresponding one of the waveguides in the waveguide. The output coupler may transmit the world light. A second biasing lens may transmit the world light and the image light to the eye comfort zone. An electro-adjustable coloring layer may transmit the world light toward the output coupler. The coloring layer may be planar and may be laminated to a planar surface of the first biasing lens and / or to a planar surface of an additional lens having curvature. If desired, the coloring layer may be separated from the first biasing lens by an air gap. If desired, the coloring layer may be tilted at a non-parallel angle with respect to the surface of the waveguide.

[0006] If desired, the coloring layer may be curved and may be separated from both the first biasing lens and the waveguide by an air gap. An interface within the coloring layer may be selected to minimize the reflectivity of the image light. If the coloring layer is planar, the coloring layer may have one or more features that enhance its planarity and parallelism with the waveguide, including an increased substrate thickness, a set of spacers between the substrates of the coloring layer, and / or a spacer between the coloring layer and the waveguide. If desired, one or more of the air gaps may be filled with a low refractive index material. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a view of an exemplary system having a display in accordance with some embodiments.

[0008] Figure 2 is a top view of an exemplary optical system for a display having a waveguide, the waveguide having a lens and a coloring layer for providing a virtual object overlaid with a real-world object to an eye zone.

[0009] Figure 3 and Figure 4 is a top view showing how an exemplary planar coloring layer can be laminated onto a lens overlapping a waveguide.

[0010] Figure 5 is a top view showing how an exemplary curved coloring layer can be laminated onto an inner surface of a lens overlapping a waveguide.

[0011] Figure 6 is a top view showing how an exemplary curved coloring layer can be laminated onto an outer surface of a lens overlapping a waveguide.

[0012] Figure 7 is a top view showing how an exemplary tilted planar coloring layer can be laminated onto a lens overlapping a waveguide.

[0013] Figure 8 is a top view showing how an exemplary planar coloring layer can be separated from a lens overlapping a waveguide by an air gap.

[0014] Figure 9 is a top view showing how an exemplary curved coloring layer can be separated from a lens overlapping a waveguide by an air gap.

[0015] Figure 10 is a top view of an exemplary coloring layer having a pair of glass substrates in accordance with some embodiments.

[0016] Figure 11 is a top view of an exemplary coloring layer having a single glass substrate in accordance with some embodiments.

[0017] Figure 12 is a top view showing how an electrical signal can be provided to an exemplary coloring layer to dynamically adjust the amount of light transmitted by the coloring layer in accordance with some embodiments.

[0018] Figure 13 is a top view showing how an increased thickness and / or spacers located between the coloring layer and the waveguide can be provided for an exemplary planar coloring layer to maximize the parallelism between the coloring layer and the waveguide in accordance with some embodiments.

[0019] Figure 14 is a top view showing how spacers located between glass substrates can be arranged for an exemplary planar coloring layer to maximize parallelism within the coloring layer according to some embodiments.

[0020] Figure 15 is a top view showing how a low refractive index coating can fill an air gap between a lens and a waveguide according to some embodiments. DETAILED DESCRIPTION

[0021] Figure 1 The system 10 can be an electronic device (such as a head-mounted device) having one or more displays. The display in the system 10 can include a near-eye display 20 mounted within a support structure (such as the housing 14). The housing 14 can be shaped like a pair of glasses or goggles (e.g., a support frame), can form a housing having a helmet shape, or can have other configurations for assisting in mounting and fixing the near-eye display 20 components on or near the user's head. The near-eye display 20 can include one or more display projectors (such as the projector 26 (sometimes referred to herein as the display module 26)) and one or more optical systems (such as the optical system 22). The projector 26 can be mounted in a support structure such as the housing 14. Each projector 26 can emit image light 30, which is redirected toward the user's eyes at the comfortable viewing zone 24 using an associated one of the optical systems in the optical system 22. The image light 30 is, for example, visible light (e.g., including wavelengths from 400 nm to 700 nm) that contains and / or represents visual content such as a scene or an object (e.g., modulated onto the image light using image data provided to the display module by the control circuit).

[0022] The control circuit 16 can be used to control the operation of the system 10. The control circuit 16 can include storage and processing circuitry for controlling the operation of the system 10. The control circuit 16 can include storage devices such as hard disk drive storage, non-volatile memory (e.g., electrically programmable read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random access memory), etc. The processing circuitry in the control circuit 16 can include one or more processors (e.g., microprocessors, microcontrollers, digital signal processors, baseband processors, etc.), a power management unit, an audio chip, a graphics processing unit, application-specific integrated circuits, and other integrated circuits. Software code can be stored on the storage device in the control circuit 16 and run on the processing circuitry in the control circuit 16 to implement operations for the system 10 (e.g., data acquisition operations, operations involving regulating components using control signals, image rendering operations for generating image content to be displayed to the user, etc.).

[0023] System 10 may include input-output circuitry such as input-output device 12. Input-output device 12 may be used to allow system 10 to receive data from external equipment (e.g., a tethered computer, a portable device such as a handheld device or a laptop computer, or other electrical equipment), and to allow a user to provide user input to the head-mounted device 10. Input-output device 12 may also be used to collect information about the environment in which system 10 (e.g., head-mounted device 10) operates. The output component in device 12 may allow system 10 to provide output to the user, and may be used to communicate with external electronic equipment. Input-output device 12 may include sensors and other components 18 (e.g., an image sensor for acquiring an image of a real-world object that is digitally merged with a virtual object on a display in system 10, an accelerometer, a depth sensor, a light sensor, a haptic output device, a speaker, a battery, a wireless communication circuit for communicating between system 10 and an external electronic device, etc.).

[0024] Projector 26 may include a liquid crystal display, an organic light-emitting diode display, a laser-based display, or other types of displays. Projector 26 may include a light source, an emissive display panel, a transmissive display panel illuminated with illumination light from the light source to generate image light, a reflective display panel (such as a digital micromirror device (DMD) panel and / or a liquid crystal on silicon (LCOS) display panel) illuminated with illumination light from the light source to generate image light 30, etc.).

[0025] Optical system 22 may form lenses that allow a viewer (see, e.g., the eyes of the viewer at the eye box 24) to view the images on display 20. There may be two optical systems 22 associated with the user's respective left and right eyes (e.g., for forming a left lens and a right lens). A single display 20 may generate images for both eyes, or a pair of displays 20 may be used to display images. In a configuration having multiple displays (e.g., a left-eye display and a right-eye display), the focal length and position of the lenses formed by system 22 may be selected such that any gap present between the displays will be invisible to the user (e.g., such that the images of the left display and the right display seamlessly overlap or merge).

[0026] If desired, the optical system 22 may include components (e.g., an optical combiner formed by reflective components, diffractive components, waveguides, direct-view optical combiners, etc.) to allow real-world light (sometimes referred to as world light) from real-world (external) objects such as real-world (external) object 28 to be optically combined with virtual (computer-generated) images such as the virtual image in image light 30. In this type of system (sometimes referred to as an augmented reality system), a user of system 10 may view both real-world content (e.g., world light from object 28) and computer-generated content overlaid on the real-world content. A camera-based augmented reality system may also be used in device 10 (e.g., in an arrangement where a camera captures a real-world image of object 28 and digitally combines the content with the virtual content of optical system 22).

[0027] If desired, system 10 may include wireless circuitry and / or other circuitry to support communication with a computer or other external equipment (e.g., a computer that supplies image content to display 20). During operation, control circuit 16 may provide image content to display 20. The content may be received remotely (e.g., from a computer or other content source coupled to system 10), and / or the content may be generated by control circuit 16 (e.g., text, other computer-generated content, etc.). The content provided by control circuit 16 to display 20 may be viewed by a viewer at the eyepiece area 24.

[0028] If desired, system 10 may include an optical sensor. The optical sensor may be used to collect optical sensor data associated with the user's eyes at the eyepiece area 24. The optical sensor may be, for example, a gaze tracking sensor that collects optical sensor data such as gaze image data (gaze tracking image data or gaze tracking sensor data) from the user's eyes at the eyepiece area 24. Control circuit 16 may process the optical sensor data to identify and track in real time the direction of the user's gaze. Control circuit 16 may perform any required operations based on the direction of the user's gaze tracked over time.

[0029] As Figure 1As shown, the optical sensor (gaze tracking sensor) may include one or more optical transmitters such as infrared transmitter 8 and one or more optical receivers (sensors) such as infrared sensor 6 (sometimes referred to herein as optical sensor 6). The infrared transmitter 8 may include one or more light sources that emit sensing light (such as light 4). The light 4 may be used to perform optical sensing (e.g., gaze tracking) on / at the eye comfort zone 24, rather than transporting image data pixels such as in the image light 30. The light 4 may include infrared light. The infrared light may be at an infrared (IR) wavelength and / or a near-infrared (NIR) wavelength (e.g., any desired wavelength from about 700 nm to about 15 microns). Optionally or alternatively, the light 4 may include wavelengths less than 700 nm if needed. Thus, the light 4 may sometimes be referred to herein as sensor light 4.

[0030] The infrared transmitter 8 may direct the light 4 towards the optical system 22. The optical system 22 may direct the light 4 emitted by the infrared transmitter 8 towards the eye comfort zone 24. The light 4 may be reflected from various parts (regions) of the user's eye located at the eye comfort zone 24 as reflected light 4R (sometimes referred to herein as reflected sensor light 4R, which is a reflected version of the light 4). The optical system 22 may receive the reflected light 4R and may direct the reflected light 4R towards the infrared sensor 6. The infrared sensor 6 may receive the reflected light 4R from the optical system 22 and may collect (e.g., generate, measure, sense, produce, etc.) optical sensor data in response to the received reflected light 4R. For example, the infrared sensor 6 may include an image sensor or a camera (e.g., an infrared image sensor or a camera). The infrared sensor 6 may include, for example, one or more image sensor pixels (e.g., an array of image sensor pixels). The optical sensor data may include image sensor data (e.g., image data, infrared image data, one or more images, etc.). The infrared sensor 6 may transfer the optical sensor data to the control circuit 16 for further processing. Optionally, the infrared sensor 6 and the infrared transmitter 8 may be omitted.

[0031] Figure 2 is exemplary that can be used in Figure 1 system 10 of the top view of the display 20. As Figure 2 shown, the display 20 may include a projector such as projector 26 and an optical system such as optical system 22. The optical system 22 may include optical elements such as one or more waveguides 32. The waveguides 32 may include one or more stacked substrates (e.g., stacked planar and / or curved layers, sometimes referred to herein as "waveguide substrates") formed of an optically transparent material such as plastic, polymer, glass, etc.

[0032] If desired, waveguide 32 may also include one or more layers of holographic recording medium (sometimes referred to herein as "holographic medium", "grating medium", or "diffractive grating medium") on which one or more diffractive gratings (e.g., holographic phase gratings, sometimes referred to herein as "holograms", surface relief gratings, etc.) are recorded. Holographic recording may be stored as an optical interference pattern (e.g., alternating regions of different refractive indices) within a photosensitive optical material such as the holographic medium. This optical interference pattern may create a holographic phase grating that, when illuminated with a given light source, diffracts light to produce a three-dimensional reconstruction of the holographic recording. The holographic phase grating may be a non-switchable diffractive grating encoded with a permanent interference pattern, or it may be a switchable diffractive grating where the diffracted light can be modulated by controlling the electric field applied to the holographic recording medium. If desired, multiple holographic phase gratings (holograms) may be recorded within the same volume of holographic medium (e.g., superimposed within the same volume of grating medium). The holographic phase grating may be, for example, a volume hologram or a thin-film hologram within the grating medium. The grating medium may include photopolymers, gelatin such as dichromated gelatin, silver halide, holographic polymer dispersed liquid crystals, or other suitable holographic media.

[0033] The diffractive grating on waveguide 32 may include a holographic phase grating such as a volume hologram or a thin-film hologram, a meta-grating, or any other desired diffractive grating structure. The diffractive grating on waveguide 32 may also include a surface relief grating (SRG) formed on one or more surfaces of the substrate within waveguide 32 (e.g., as a modulation of the thickness of an SRG medium layer). The diffractive grating may, for example, include multiple multiplexed gratings (e.g., holograms) that at least partially overlap within the same volume of grating medium (e.g., for diffracting light of different colors and / or light from different input angle ranges at one or more corresponding output angles). If desired, other light redirecting elements such as a shutter mirror may be used in place of the diffractive grating in waveguide 32.

[0034] As Figure 2 shown, projector 26 may generate (e.g., produce and emit) image light 30 associated with the image content to be displayed in the eyebox 24 (e.g., image light 30 may convey a series of image frames for display at eyebox 24). If desired, a collimating lens in projector 26 may be used to collimate image light 30. Optical system 22 may be used to present the image light 30 output from projector 26 to eyebox 24. If desired, projector 26 may be mounted within Figure 1 support structure 14, while optical system 22 may be mounted between portions of support structure 14 (e.g., to form a lens aligned with eyebox 24). If desired, other mounting arrangements may be used.

[0035] The optical system 22 may include one or more optical couplers (e.g., light redirecting elements) such as an input coupler 34, a cross-coupler 36, and an output coupler 38. In Figure 2 the example of, the input coupler 34, the cross-coupler 36, and the output coupler 38 are formed at or on the waveguide 32. The input coupler 34, the cross-coupler 36, and / or the output coupler 38 may be fully embedded within the substrate layer of the waveguide 32, may be partially embedded within the substrate layer of the waveguide 32, may be mounted to the waveguide 32 (e.g., mounted to the outer surface of the waveguide 32), etc.

[0036] The waveguide 32 may guide the image light 30 along its length via total internal reflection. The input coupler 34 may be configured to couple the image light 30 from the projector 26 into the waveguide 32 (e.g., within the total internal reflection (TIR) range of the waveguide, within which light propagates along the waveguide via TIR), while the output coupler 38 may be configured to couple the image light 30 from within the waveguide 32 (e.g., propagating within the TIR range) to the outside of the waveguide 32 and toward the eye zone 24 (e.g., at an angle outside the TIR range). The input coupler 34 may include an input coupling prism, an edge or face of the waveguide 32, a lens, a steering mirror or a liquid crystal steering element, a diffraction grating structure (e.g., a volume hologram, an SRG, etc.), a partially reflective structure (e.g., a Venetian mirror), or any other desired input coupling element.

[0037] For example, the projector 26 may emit the image light 30 in the +Y direction toward the optical system 22. When the image light 30 impinges on the input coupler 34, the input coupler 34 may redirect the image light 30 such that the light propagates within the waveguide 32 via total internal reflection toward the output coupler 38 (e.g., in the +X direction within the TIR range of the waveguide 32). When the image light 30 impinges on the output coupler 38, the output coupler 38 may redirect the image light 30 away from the waveguide 32 toward the eye zone 24 (e.g., backward along the Y axis). In a particular implementation where the cross-coupler 36 is formed on the waveguide 32, the cross-coupler 36 may redirect the image light 30 in one or more directions as the image light 30 propagates down the length of the waveguide 32 (e.g., from the propagation direction coupled into the waveguide by the input coupler toward the output coupler 38). When redirecting the image light 30, the cross-coupler 36 may also perform pupil expansion on the image light 30 in one or more directions. When expanding the pupil of the image light, the cross-coupler 36 may, for example, help reduce the vertical size (e.g., in the Z direction) of the waveguide 32 relative to a particular implementation that omits the cross-coupler 36. Thus, the cross-coupler 36 may sometimes also be referred to herein as the pupil expander 36 or the optical expander 36. If desired, the output coupler 38 may also expand the image light 30 when coupling the image light out of the waveguide 32.

[0038] Input coupler 34, cross-coupler 36, and / or output coupler 38 may be based on reflective and refractive optical devices, or may be based on diffractive (e.g., holographic) optical devices. In an arrangement where couplers 34, 36, and 38 are formed of reflective and refractive optical devices, couplers 34, 36, and 38 may include one or more reflectors (e.g., an array of micromirrors, partial mirrors, shutter mirrors, or other reflectors). In an arrangement where couplers 34, 36, and 38 are based on diffractive optical devices, couplers 34, 36, and 38 may include diffraction gratings (e.g., volume holograms, surface relief gratings, etc.).

[0039] Figure 2 The examples of ,

[0039] , and Figure 2 are illustrative only. Optical system 22 may include a plurality of waveguides stacked laterally and / or vertically relative to each other. Each waveguide may include one coupler, two couplers, all couplers, or none of couplers 34, 36, and 38. If desired, waveguide 32 may be at least partially curved or bent. One or more of couplers 34, 36, and 38 may be omitted. If desired, optical system 22 may include a single optical coupler (sometimes referred to herein as a staggered coupler, diamond coupler, or diamond expander) that performs the operations of both cross-coupler 36 and output coupler 38, or cross-coupler 36 may be separate from output coupler 38.

[0040] Figure 2 The operation of optical system 22 on image light 30 is shown in Figure 2 . Optical system 22 may also direct light 4 from infrared emitter 8 toward the eye zone 24, and may direct reflected light 4R from eye zone 24 toward infrared sensor 6 ( Figure 1 ). Additionally, output coupler 38 may form an optical combiner for image light 30 and world light from a real-world object (such as real-world object 28). As Figure 2 shown, world light from real-world object 28 may pass through output coupler 38, which transmits the world light (e.g., without diffracting the world light) to eye zone 24.

[0041] Image light 30 may include an image of a virtual object, sometimes referred to herein as a virtual object image or simply a virtual object. Projector 26 may receive image data (e.g., pixels of image data at different pixel positions forming the virtual object image) including the virtual object image. Output coupler 38 may be used to overlay the virtual object image with world light from real-world object 28 within the field of view (FOV) of eye zone 24. The control circuit of system 10 may provide image data to projector 26, which places the virtual object image at a desired position within the FOV of eye zone 24 (e.g., such that the virtual object image overlaps a desired real-world object in the scene / environment in front of system 10).

[0042] The optical system 22 may include one or more lenses 40 that overlap with the output coupler 38. For example, the optical system 22 may at least include a first lens 40A and a second lens 40B. The lens 40B may be interposed between the waveguide 32 and the real-world object 28. The lens 40A may be interposed between the waveguide 32 and the eye comfort zone 24. The lenses 40 are transparent and allow world light from the real-world object 28 to be transmitted to the eye comfort zone 24 for the user to view. At the same time, the user may view the virtual object image that is guided out of the waveguide 32 and reaches the eye comfort zone 24 through the lens 40A. The lenses 40A and 40B may also sometimes be referred to as lens elements in this document.

[0043] The strength (sometimes referred to as optical power, power, or diopter) of the lens 40A may be selected to place the virtual object image in the image light 30 at a desired image distance (depth) from the eye comfort zone 24 (sometimes referred to as virtual object distance, virtual object image distance, virtual image distance (VID), virtual object depth, virtual image depth, or image depth) in this document. For example, it may be desirable to place a virtual object (virtual object image) such as text, icons, moving images, characters, effects, or other content or features at a certain virtual image distance (e.g., to integrate the virtual object image within, on, in the middle of, or around the real-world object in front of the system 10). The placement of the virtual object at that distance can be achieved by appropriately selecting the strength of the lens 40A. The lens 40A may be a negative lens for a user with no refractive error in the eyes. Therefore, the strength (larger net negative optical power) of the lens 40A may be selected to adjust the distance (depth) of the virtual object. Therefore, the lens 40A may sometimes be referred to as the biasing lens 40A or the bias (B-) lens 40A in this document.

[0044] If desired, the lens 40B may have a complementary optical power value (e.g., positive optical power, the magnitude of which matches the magnitude of the negative optical power of the lens 40A). Therefore, the lens 40B may sometimes be referred to as the bias+(B+) lens 40B, the complementary lens 40B, or the compensating lens 40B in this document. For example, if the lens 40A has an optical power of -2.0 diopters, the lens 40B may have an equal and opposite optical power of +2.0 diopters (as an example). In this type of arrangement, the positive optical power of the lens 40B cancels out the negative optical power of the lens 40A. Therefore, the total optical power of the lenses 40A and 40B together will be 0 diopters. This allows the viewer to view real-world objects (such as the real-world object 28) without the optical influence from the lenses 40A and 40B. For example, a real-world object 28 located far away from the system 10 (effectively at infinity) can be regarded as if the lenses 40A and 40B do not exist.

[0045] For users with satisfactory uncorrected vision, this type of complementary lens arrangement thus allows a virtual object to be placed close to the user (e.g., at a virtual image distance of 0.5 m to 5 m, at least 0.1 m, at least 1 m, at least 2 m, less than 20 m, less than 10 m, less than 5 m or at other suitable near-middle distances from the device 10), while allowing the user to view real-world objects without modification through the optical components of the optical system. For example, a real-world object located at a distance of 2 m from the device 10 (e.g., a real-world object marked by a virtual text label at a virtual image distance of 2 m) will optically appear to be located at 2 m from the device 10. This is merely illustrative, and if desired, the lenses 40A and 40B need not be complementary lenses (e.g., the lenses 40A and 40B can have any desired optical power).

[0046] In addition, some users may require vision correction. Vision correction can be provided using tunable lenses, fixed (e.g., removable) lenses (sometimes referred to as supplementary lenses, vision correction lenses, removable lenses or clip-on lenses) and / or by adjusting the optical power of the lens 40A and / or the lens 40B to achieve the desired vision correction. Generally speaking, the vision correction imparted to the lens can include correction of refractive errors (eyes with refractive errors), such as lenses for correcting myopia (nearsightedness), correction of hyperopia (farsightedness), correction of astigmatism, correction of strabismus, correction for helping to accommodate for the reduction in the age-related accommodation range exhibited by the eye (sometimes referred to as presbyopia) and / or correction of other vision impairments.

[0047] The lenses 40A and 40B can be provided with any desired optical power and any desired shape (e.g., they can be plano-convex lenses, plano-concave lenses, plano-freeform lenses, freeform convex lenses, freeform concave lenses, convex-concave freeform-freeform lenses, etc.). Specific embodiments in which the optical power of the lens 40A and / or the lens 40B is fixed (e.g., during manufacturing) are described herein as examples. If desired, one or both of the lenses 40A and / or 40B can be electrically adjustable to impart different optical powers or optical power distributions over time (e.g., the lenses 40A and / or 40B can be adjustable / tunable liquid crystal lenses).

[0048] Under some operating conditions, such as when operating the system 10 outdoors, in a room with bright illumination, or in other environments with relatively high light intensity, the world light from the real-world object 28 may suppress or wash out the virtual object presented in the image light 30 to the eye comfort zone 24, thereby limiting the contrast and visibility of the virtual object when viewed at the eye comfort zone 24. To reduce the brightness of the world light and maximize the contrast of the image (virtual object) in the image light 30 when viewed at the eye comfort zone 24, the optical system 22 may include a light absorption layer (such as the coloring layer 42). The coloring layer 42 may be disposed in the optical path between the real-world object 28 and the output coupler 38. The world light from the real-world object 28 may pass through the coloring layer 42 before reaching the eye comfort zone 24 (e.g., the coloring layer 42 may transmit the world light but not transmit the image light 30). The coloring layer 42 may absorb some of the real-world light in the real-world light, thereby reducing its brightness and increasing the contrast of the virtual object in the image light 30 at the eye comfort zone 24. If desired, even when the virtual image is turned off, the coloring layer may be used to absorb the real-world light, thereby performing a function similar to that of switchable sunglasses.

[0049] The coloring layer 42 may be a fixed coloring layer or may be a dynamically adjustable coloring layer. When implemented as a fixed coloring layer, the coloring layer 42 has a fixed transmission profile that absorbs the same amount of incident world light over time. The fixed coloring layer may be formed of a polymer film containing dyes and / or pigments (as an example). When implemented as a dynamically (electrically) adjustable coloring layer, the coloring layer 42 has a dynamically (electrically) adjustable transmission profile. In these embodiments, the coloring layer 42 may be controlled by a control signal from the control circuit 16. Embodiments in which the coloring layer 42 is a dynamically adjustable coloring layer are described herein as examples. However, generally speaking, the coloring layer 42 as described herein may be replaced with a fixed coloring layer.

[0050] The electro - adjustable coloring layer (sometimes referred to as an electro - adjustable light modulator or electro - adjustable light modulator layer) can be formed from an organic or inorganic electrochromic light modulator layer or a guest - host liquid crystal light modulator layer. When implemented using an organic electrochromic coloring material, the active coloring material in the coloring layer can be formed from one or more polymer layers that change their absorption when oxidized or reduced by charges from an adjacent electrode, or the active coloring material in the coloring layer can be made from one or more organic small - molecule substances that diffuse in a liquid or gel medium and change their absorption when oxidized or reduced by charges from an adjacent electrode. When implemented using an inorganic electrochromic coloring material, the active coloring material can be formed from one or more metal oxides that change their absorption when oxidized or reduced by charges from an adjacent electrode and can include counterions. During operation of system 10, when it is desired to enhance the visibility of real - world objects, the electro - adjustable coloring layer can be dynamically placed in a high - transmission mode (sometimes referred to herein as a clear state), or when it is desired to reduce the scene brightness and thereby help enhance the visibility of the image light from projector 26, the electro - adjustable coloring layer can be dynamically placed in a lower - transmission mode (sometimes referred to herein as a dark state) (e.g., to allow viewing of virtual objects such as those in image light 30 without being overwhelmed by bright ambient light). If desired, the coloring layer 42 can also be controlled to exhibit intermediate transmission levels and / or transmission levels that vary across the entire field of view of the eye - comfort zone 24.

[0051] The coloring layer 42 can be planar (e.g., having side surfaces located in a flat plane), or can be curved (e.g., having curved and non - planar side surfaces). The coloring layer 42 can be disposed at any desired location between the real - world object 28 (e.g., the scene in front of system 10) and the output coupler 38 on the waveguide 32 within the optical system 22.

[0052] Figure 3 is a diagram showing one example where the coloring layer 42 is planar and disposed on the lens 40B. For clarity, Figures 3 to 15 the lens 40B and the eye - comfort zone 24 have been omitted in Figure 2 ). The lens 40B and the coloring layer 42 can overlap with the output coupler 38 on the waveguide 32.

[0053] As Figure 3 shown, the lens 40B can have a first surface 48 facing away from the waveguide 32 and the eye - comfort zone (e.g., facing Figure 2 the real - world object 28). The lens 40B can also have a second surface 50 opposite the first surface 48 and facing the waveguide 32. Surfaces 50 and 48 are the optical (transmission) surfaces of the lens 40B and thus transmit light from the real - world object 28 (Figure 2 ) world light. The optical axis of lens 40B extends through the centers of surfaces 48 and 50 (e.g., parallel to the Y-axis).

[0054] Generally speaking, surface 48 can be planar (flat), can be one-dimensionally curved (e.g., can be a developable surface curved around a single axis and thus can be flattened into a plane without distortion), can be two-dimensionally curved (e.g., can be a non-developable surface curved around multiple axes such that the surface cannot be flattened into a plane without distortion), can be spherically curved, can be aspherically curved, can be ellipsoidally curved, can be cylindrically curved, can be toroidally curved, can be convex, can be concave, can be free-form curved, or can exhibit two or more of these curvatures. Similarly, surface 50 can be planar, can be one-dimensionally curved, can be two-dimensionally curved, can be spherically curved, can be aspherically curved, can be ellipsoidally curved, can be cylindrically curved, can be toroidally curved, can be convex, can be concave, can be free-form curved, or can exhibit two or more of these curvatures. Surface 50 can have the same curvature as surface 48 (e.g., surface 50 can extend parallel to surface 48), or can have a different curvature from surface 48 (e.g., surfaces 48 and 50 can be non-parallel). For illustrative purposes, in Figure 3 the example, surface 48 is convex and surface 50 is planar.

[0055] As Figure 3 shown, the coloring layer 42 can be laminated onto the surface 50 of lens 40B. Thus, the coloring layer 42 can conform to the shape of the surface 50 of lens 40B (e.g., the coloring layer 42 can be planar). If desired, additional lenses such as lens 46 can be provided on the coloring layer 42 (e.g., the coloring layer 42 can be sandwiched or interposed between lens 40B and lens 46). Lens 46 may sometimes be referred to herein as lens element 46. Lens 46 can have a first surface 52 that contacts the coloring layer 42 and a second surface 54 opposite that faces the waveguide 32. The waveguide 32 can have a side surface 44 that faces the lens 40B. For example, the side surface 44 can be a planar surface (e.g., extending parallel to the surface 50 of lens 40B). The surface 54 of lens 46 can be separated from the side surface 44 of the waveguide 32 by an air gap 56.

[0056] Generally speaking, the surface 52 can be planar, can be one-dimensionally curved, can be two-dimensionally curved, can be spherically curved, can be aspherically curved, can be ellipsoidally curved, can be cylindrically curved, can be toroidally curved, can be convex, can be concave, can be free-form curved, or can exhibit two or more of these curvatures. Similarly, the surface 54 can be planar, can be one-dimensionally curved, can be two-dimensionally curved, can be spherically curved, can be aspherically curved, can be ellipsoidally curved, can be cylindrically curved, can be toroidally curved, can be convex, can be concave, can be free-form curved, or can exhibit two or more of these curvatures. The surface 52 can have the same curvature as the surface 54 (e.g., the surface 52 can extend parallel to the surface 54), or can have a different curvature from the surface 54 (e.g., the surfaces 52 and 54 can be non-parallel).

[0057] In Figure 3 the example of, the surface 52 is planar and the surface 54 is convex. During the display operation, the output coupler 38 redirects most of the image light 30 in the image light towards the eyebox 24 ( Figure 2 ). However, in practice, some of the image light 30 may also leak upwards towards the color layer 50 (e.g., after interacting with the output coupler 38 and / or after reflecting from the side surface of the waveguide 32 opposite to the side surface 44). This image light can illuminate the color layer 42 and be reflected back by the color layer 42 to the eyebox ( Figure 2 ). The portion of this image light that leaks out of the waveguide 32 and is reflected by the color layer 42 may sometimes be referred to herein as the reflected image light, while the portion of this image light that is coupled out of the waveguide 32 by the output coupler 38 and towards the eyebox may sometimes be referred to herein as the primary image light. If not careful, this reflected image light may be misaligned relative to the primary image light, thus creating an unsightly ghost image artifact at the eyebox 24.

[0058] If desired, the curvature of the surface 54 of the lens 46 can impart optical power to the reflected image light generated by the color layer 42. The optical power can be used to defocus (blur) the reflected light (e.g., the virtual image in the reflected image light) at the location of the eyebox 24, thereby helping to reduce the visibility of the ghost image artifact at the eyebox 24 (e.g., by placing the reflected light outside the accommodation range of the eye). However, Figure 3 the concave curvature of the surface 54 in the example of may cause an undesirable competition between the reflected image light and the primary image light coupled out of the waveguide 32 by the output coupler 38.

[0059] To alleviate these problems, the surface 54 can be provided with as Figure 4The convex curvature as shown in the example. When the surface 54 is provided with a convex curvature, the lens 46 can impart a focal power to the reflected image light without causing the reflected image light to compete with the main image light at the exit pupil region 24.

[0060] In Figure 3 and Figure 4 's example, the lens 46 imparts a focal power to the reflected image light, and the coloring layer 42 is planar. If desired, the coloring layer 42 can be curved to impart a focal power to the reflected image light without using the lens 46. Figure 5 is a diagram showing an example of how the coloring layer 42 can be curved to impart a focal power to the reflected image light without using the lens 46.

[0061] As Figure 5 shown, the surface 50 of the lens 40B can be curved, and the coloring layer 42 can be disposed on the surface 50, thereby imparting the base curvature of the surface 50 to the coloring layer 42. The curvature of the surface 50 and thus the curvature of the coloring layer 42 can be selected to impart a desired focal power to the reflected image light, thereby blurring the image in the image light reflected from the coloring layer 42 without causing the reflected image light to compete with the main image light coupled out of the waveguide 32 by the output coupler 38.

[0062] Figure 5 's example in which the coloring layer 42 is disposed on the surface 50 of the lens 40B is illustrative and not restrictive. If desired, the coloring layer 42 can be disposed on the surface 48 of the lens 40B, as Figure 6 's example shows. As Figure 6 shown, the curvature of the surface 48 and thus the curvature of the coloring layer 42 can be selected to impart a desired focal power to the reflected image light (e.g., when reflected from the coloring layer 42), thereby defocusing the reflected image light without causing the reflected image light to compete with the main image light at the exit pupil region 24.

[0063] The coloring layer 42 ( Figure 5 and Figure 6 ) or the surface 54 ( Figure 4) The curvature can have, for example, the following radii of curvature: 50 mm - 250 mm, 60 mm - 510 mm, 110 mm - 550 mm, 100 mm - 200 mm, 150 mm - 510 mm, 300 mm - 600 mm, 410 mm - 510 mm, greater than 10 mm, greater than 100 mm, greater than 200 mm, greater than 300 mm, greater than 400 mm, greater than 500 mm, less than 500 mm, less than 400 mm, less than 200 mm, less than 100 mm, or other values. The radius of curvature can depend, for example, on the reflectivity of the coloring layer 42 (e.g., 0.1% - 3%, 0.2% - 4%, or other values). The curved coloring layer 42 can be used, for example, to reduce the volume and weight of the optical system 22 (e.g., by allowing the omission of the lens 46), and can make the reflected image light even more defocused than in a particular implementation where a lens 46 is used to defocus the reflected image light.

[0064] If desired, the coloring layer 42 can be planar and can be inclined at a non - parallel angle with respect to the side surface 44 of the waveguide 32. Figure 7 is a diagram showing an example of how the coloring layer 42 can be planar and can be inclined at a non - parallel angle with respect to the side surface 44 of the waveguide 32.

[0065] As Figure 7 shown, the surface 50 of the lens 40B can be planar and can be inclined at a non - parallel angle with respect to the side surface 44 of the waveguide 32. The coloring layer 42 can be disposed on the surface 50 and can thus also be planar and inclined at a non - parallel angle with respect to the side surface 44 of the waveguide 32. If desired, the coloring layer 42 can be sandwiched between the lens 40B and the lens 46 (e.g., the surface 52 can be planar and inclined to conform to the surface 50 of the coloring layer 42 and the lens 40B), or the lens 46 can be omitted. Tilting the coloring layer 42 in this way can configure the coloring layer 42 to reflect the image light leaking from the waveguide 32 at an angle pointing away from the eye - comfort zone towards the lens 40B, thereby preventing the reflected image light from being visible within the eye - comfort zone. The tilted coloring layer can be inclined at a non - parallel angle with respect to the side surface 44 and can be embedded in one or more other optical elements (e.g., Figure 7 the lenses 40B and 46 in the example of). In other particular implementations, the tilted coloring layer can be independent and not in contact with any other optical elements. For example, the coloring layer 42 can be tilted and separated from the lens 40B and / or the lens 46 by an air gap (e.g., the lens 46 can also be omitted).

[0066] Figures 3 to 7 The example where the coloring layer 42 is disposed on the lens 40B is illustrative and not restrictive. If desired, the coloring layer 42 can be separated from the lens 40B by an air gap. Figure 8FIG. is an illustration showing one example of how the coloring layer 42 can be separated from the lens 40B by an air gap.

[0067] As Figure 8 shown, the coloring layer 42 can be disposed between the lens 40B and the waveguide 32 within the optical system 22. The coloring layer 42 can be separated from the surface 50 (e.g., a planar surface or a surface having another shape) of the lens 40B by an air gap 58. In Figure 8 the example, the coloring layer 42 is planar and laminated onto the surface 52 of the lens 46 (e.g., the lens 46 can form a substrate for the coloring layer 42), and this coloring layer is separated from the waveguide 32 by an air gap 56. For example, the lens 46 can be formed of plastic. The lens 46 can be used to defocus the reflected image light from the coloring layer 42.

[0068] Figure 8 The example in which the coloring layer 42 is planar and laminated onto the lens 46 is illustrative and not restrictive. If desired, the coloring layer 42 can be independent and curved, as in the example of Figure 9 As Figure 9 shown, the coloring layer 42 can be separated from the surface 50 (e.g., a curved surface or a surface having another shape) of the lens 40B by an air gap 58, and can be separated from the side surface 44 of the waveguide 32 by an air gap 56.

[0069] For example, the coloring layer 42 can be one-dimensionally curved (e.g., can have one-dimensional curvature), can be two-dimensionally curved (e.g., can have two-dimensional curvature), can be spherically curved (e.g., can have spherical curvature), can be aspherically curved (e.g., can have aspherical curvature), can be ellipsoidally curved (e.g., can have ellipsoidal curvature), can be cylindrically curved (e.g., can have elliptical curvature), can be toroidally curved (e.g., can have toroidal curvature), can be free-form curved (e.g., can have free-form curvature), or can exhibit two or more of these curvatures. The curvature of the coloring layer 42 can be selected to impart a desired optical power to the reflected image light so as to defocus the reflected image light without causing the reflected image light to compete with the main image light at the exit pupil (e.g., Figure 9 the coloring layer 42 can have the same curvature as the Figure 5 surface 50 or the Figure 6 surface 48). In another specific embodiment, the lens 40B can be interposed between the coloring layer 42 and the waveguide 32 (e.g., the coloring layer 42 can be separated from the surface 48 of the lens 40B by an air gap). In Figures 3 to 9 the example, the curvature of the lens 40A ( Figure 2 ) and / or the lens 40B can be selected to additionally reverse any optical power imparted to the world light transmitted through the coloring layer 42 and the lens 40B in order to defocus the reflected image light.

[0070] Figure 10 is a cross-sectional top view of an exemplary coloring layer 42. As Figure 10 shown, the coloring layer 42 may include a first substrate layer and a second substrate layer, such as substrate 70. The substrate 70 may include glass (e.g., the substrate 70 may be a glass layer), a polymer (e.g., plastic), or other transparent materials. The coloring material 64 may be formed in a layer between the substrates 70 (e.g., disposed in a chamber between the side surfaces of the substrates 70). A peripheral adhesive ring, such as the peripheral seal 62, may be used to contain the coloring material 64 while spacing the substrates 70 apart from each other. The coloring material 64 may be formed of an EC material (organic or inorganic material), such as an electrochromic (EC) gel, a guest-host liquid crystal material, and / or other electro-adjustable coloring materials.

[0071] As Figure 10 shown, the coloring layer 42 may have a first transparent conductive layer and a second transparent conductive layer 66 (e.g., an indium tin oxide layer or other transparent conductive coating material layer) located on opposite sides of the coloring material 64 (e.g., on the inner side surfaces of the substrates 70). The terminals 60 may receive a control voltage from the control circuit 16 ( Figure 1 ). By adjusting the voltage across the terminals 60, the electric field applied to the coloring material 64 by the electrodes 66 can be adjusted, thereby adjusting the amount of light transmission exhibited by the coloring material 64 and thus the coloring layer 42. In the exemplary configuration, the coloring layer 42 may exhibit a variable amount of light transmission that varies continuously between a minimum level TMIN and a maximum level TMAX. The value of TMIN may be 5%, 10%, 15%, 20%, 2%-15%, 3%-25%, 5%-40%, 10%-30%, 10%-25%, at least 3%, at least 6%, at least 15%, at least 20%, less than 35%, less than 25%, less than 15%, or other suitable minimum level that is sufficient to help reduce ambient (real-world) light during viewing of a computer-generated image from the projector 26 under bright ambient lighting conditions. The value of TMAX may be at least 50%, at least 60%, 60%-99%, 40%-99.9%, 80%-99%, 70%-99%, 80%-97%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, less than 99.99%, less than 99%, or other suitable maximum level that is sufficient to allow a viewer to comfortably view real-world objects through the coloring layer 42 when the projector 26 is not providing an image or in other situations where a higher transmission level is desired.

[0072] If desired, an anti-reflection coating, such as anti-reflection coating (ARC) 68, may be provided on one or both of the side surfaces of substrate 70 opposite the coloring material 64. In a particular implementation where the coloring layer 42 is curved (see, for example Figure 5 , Figure 6 and Figure 9 ), substrate 70 may be curved (e.g., the side surfaces of substrate 70 may be curved), as shown by curve 72. For example, a hot pressing and annealing process may be used to curve the glass used to form substrate 70. Then, the curved (curved surface) glass may be coated with electrode 66 and anti-reflection coating 68. Then, terminal 60 may be coupled to electrode 66 (e.g., by bonding the conductive material ACF on the flexible printed circuit to electrode 66). Then, the peripheral seal 62 (e.g., an epoxy resin ring) may be deposited on one of the substrates 70, thereby defining a chamber laterally surrounded by the peripheral seal 62. Then, the chamber may be filled with the coloring material 64, and another substrate 70 may be bonded to the peripheral seal 62, thereby sealing the coloring material 64 between the substrates 70.

[0073] In other particular implementations, substrate 70 may be formed of plastic molded or curved into a curved shape, or the coloring layer 42 may be formed between two curved molded plastic substrates. Figure 10 The example in which the coloring layer 42 includes two substrates 70 is illustrative and not restrictive. If desired, the coloring layer 42 may include only a single glass or plastic substrate 70, as shown in the example of Figure 11 . As shown in Figure 11 , electrode 66 and coloring material 64 may be deposited on the curved surface of the glass substrate 70 (e.g., using a physical vapor deposition (PVD) process, wet coating, etc.). If desired, an encapsulation layer 76 may be deposited over electrode 66 and coloring material 64. If desired, other processes may be used to form the curved coloring layer 42.

[0074] Figure 12 is an exploded cross-sectional top view of the edge region 74 of the coloring layer 42 ( Figure 10 ). As shown in Figure 12 , the coloring layer 42 may include a refractive index matching layer 82 located between electrode 66 and substrate 70. A flexible printed circuit 79 may be used to feed a control signal (voltage) to electrode 66. Contact pads 80 (e.g., metal ring pads) may be provided on electrode 66, and electrode 66 may be electrically coupled to the conductive material 78 on the flexible printed circuit 79, thereby forming terminal 60 ( Figure 10 ).

[0075] Generally speaking, the reflectivity of the coloring layer 42 is generated by various interfaces of the coloring layer 42. The reflectivity of these interfaces can be reduced to reduce the reflectivity of the coloring layer 42, and thus reduce the amount of reflected image light guided back to the eye zone (e.g., minimize the generation of ghost image artifacts at the eye zone). For example, the anti-reflection coating 68 can be configured to minimize the reflection at the interface between the substrate 70 and air. Additionally or alternatively, the refractive index matching layer 82 can be selected to effectively match the refractive index of the electrode layer 66 (e.g., ITO) with the refractive index of the substrate 70 (e.g., glass), thereby forming a smooth refractive index transition that minimizes the reflection of image light. For example, the refractive index matching layer 82 can be a multi-layer stack of thin films with a refractive index and / or thickness that is selected to produce optical reflection and transmission such that the electrode 66 and the substrate 70 exhibit the same effective refractive index. Additionally or alternatively, the refractive index matching layer 82 can be selected to effectively match the refractive index of the electrode layer 66 with the refractive index of the coloring material 64.

[0076] Figures 3 to 9 An example where a curved optical surface is used to defocus the reflected light (e.g., to mitigate ghost image artifacts at the eye zone) is illustrative and not restrictive. If desired, the coloring layer 42 and the waveguide 32 can be configured to align the main image light coupled out of the waveguide 32 by the output coupler 38 with the reflected image light from the coloring layer 42. Such alignment will also prevent the formation of visible ghost image artifacts at the eye zone.

[0077] The coloring layer 42 and the waveguide 32 can be configured to align the main image light with the reflected image light by maximizing the parallelism between the side surfaces of the coloring layer 42 and the side surfaces of the waveguide 32. In practice, there can be many sources of non-parallelism, such as imperfect waveguide flatness, imperfect coloring layer flatness, imperfect coloring cell gap uniformity, and non-parallel orientation of the coloring layer relative to the waveguide. For example, coloring layer flatness can be caused by stress imbalances in glass processing or glass coating (e.g., chemical strengthening, anti-reflection coating, electrode coating, etc.) and / or by stress imbalances in the cell assembly process (e.g., carrier tape delamination, epoxy resin stress (such as curing shrinkage), CTE mismatch with glass, and seal width uniformity, EC gel vacuum filling stress, UV plug injection pressure, and flexible printed circuit thickness).

[0078] To alleviate these problems and maximize the parallelism between the side surfaces of the coloring layer 42 and the side surfaces of the waveguide 32, the thickness of the substrate 70 in the coloring layer 42 can be increased, additional spacers can be provided between the coloring layer 42 and the waveguide 32, and / or additional spacers can be provided within the coloring layer 42. Figure 13is a diagram showing how the parallelism between the side surfaces of the coloring layer 42 and the side surfaces of the waveguide 32 can be maximized by increasing the thickness of the substrate 70 in the coloring layer 42 and / or by providing additional spacers between the coloring layer 42 and the waveguide 32. For clarity, Figure 13 and Figure 14 the electrodes, refractive index matching layer, and anti-reflection coating of Figure 12 have been omitted.

[0079] As Figure 13 shown, the coloring layer 42 can have a thickness T1 measured from the side surface 90 to the side surface 92. The side surfaces 90 and 92 can be planar. Generally speaking, compared with a smaller thickness T1, a larger thickness T1 can allow the coloring layer 42 to remain flatter more uniformly across its lateral region. For example, the coloring layer 42 can be provided with a substrate 70 having a relatively large thickness, which configures the coloring layer 42 itself to exhibit a relatively large thickness (e.g., within 50%-150% of the thickness of the waveguide 32).

[0080] If desired, the coloring layer 42 can be separated from the side surface 44 of the waveguide 32 by an air gap 86. The coloring layer 42 can be mounted to the side surface 44 of the waveguide 32 using a peripheral adhesive ring such as the peripheral seal 84 (or any other desired spacer at or along the lateral periphery of the coloring layer 42). A set of one or more additional spacers 88 (e.g., epoxy beads) can be provided (e.g., at uniform / regular intervals or other intervals across the side surface regions of the side surfaces 92 and 44) within the air gap 86 between the side surfaces 92. The spacers 88 can help ensure that the air gap 86 exhibits a uniform width across the side surfaces 92 and 44, thereby helping to enhance the flatness of the coloring layer 42 across its lateral region and thus maximizing the parallelism between the lateral surfaces 90 and 92 of the coloring layer 42 and the side surfaces 44 and 94 of the waveguide 32. This increased level of parallelism can be used, for example, to align the reflected image light with the main image light, thereby preventing the formation of visible ghost image artifacts.

[0081] Additionally or alternatively, the coloring layer 42 itself can include additional spacers for maximizing parallelism, as shown in the example of Figure 14 As Figure 14As shown, a set of one or more additional spacers 96 (e.g., epoxy beads) may be disposed within the cavity of the coloring layer 42 between the substrates 70 (e.g., within the coloring material 64, which may be filled within the cavity after the spacers 96 are placed). The spacers 96 may be placed at regular / uniform intervals or at other intervals across the lateral regions of the substrate 70. The peripheral seal 62 may laterally surround the spacers 96. The spacers 96 may help ensure that the coloring material 64 exhibits a uniform thickness across the lateral regions of the substrate 70, thereby helping to enhance the flatness of the coloring layer 42 across its lateral regions (e.g., cell gap uniformity), and thus maximizing the parallelism between the side surfaces 90 and 92 and thus the parallelism between the coloring layer 42 and the side surfaces 44 and 94 of the waveguide 32. This increased level of parallelism may be used, for example, to align the reflected image light with the primary image light, thereby preventing the formation of visible ghost image artifacts. If desired, the spacers 96 may be small enough to be invisible or indistinguishable to the human eye when located at the eyewear zone 24( Figure 2 ).

[0082] If desired, a low refractive index material may be used to fill one or more of the air gaps described herein. In the Figure 15 example, a layer of low refractive index material 98 fills the air gap between the coloring layer 42 on the inner surface of the lens 40B and the side surface 42 of the waveguide 32 (e.g., the low refractive index material 98 contacts both the coloring layer 42 and the waveguide 32). A layer of low refractive index material 100 may fill the air gap between the waveguide 32 and the lens 40A. The refractive indices of the low refractive index materials 98 and 100 may be as close as possible to the refractive index of air (e.g., about n = 1.0 - 1.5).

[0083] According to one embodiment, an electronic device is provided that includes: a waveguide configured to propagate a first light; a first lens having a first surface facing the waveguide; a second lens with the waveguide interposed between the first lens and the second lens; an optical coupler located on the waveguide, the optical coupler being configured to direct the first light out of the waveguide and through the second lens, and the first lens being configured to direct a second light through the optical coupler and the second lens; a coloring layer located on the first surface of the first lens; and a third lens having a second surface located on the coloring layer and a third surface facing the waveguide, the third lens being configured to transmit the second light to the optical coupler, and the third surface being convex.

[0084] According to another embodiment, the coloring layer is electrically adjustable.

[0085] According to another embodiment, the first surface, the coloring layer, and the second surface are planar.

[0086] According to another embodiment, the third surface is separated from the waveguide by an air gap.

[0087] According to another embodiment, the third surface has a freeform curvature, a spherical curvature, an aspherical curvature, a one-dimensional curvature, or a two-dimensional curvature.

[0088] According to one embodiment, an electronic device is provided, the electronic device including: a waveguide configured to propagate a first light and having a first planar surface and a second planar surface parallel to the first planar surface; a first lens having a third planar surface facing the waveguide, the third planar surface being inclined at a non-parallel angle with respect to the first planar surface; a second lens with the waveguide interposed between the first lens and the second lens; an optical coupler located on the waveguide, the optical coupler being configured to guide the first light out of the waveguide through the second planar surface and through the second lens, and the first lens being configured to guide a second light through the optical coupler and the second lens; and a planar coloring layer located on the third planar surface of the first lens.

[0089] According to another embodiment, the coloring layer is electrically adjustable.

[0090] According to another embodiment, the electronic device includes a third lens having a fourth planar surface located on the coloring layer and parallel to the second planar surface, the third lens being configured to transmit the second light to the optical coupler.

[0091] According to another embodiment, the first lens has a surface opposite to the third planar surface, the surface having a freeform curvature, a spherical curvature, an aspherical curvature, a one-dimensional curvature, or a two-dimensional curvature.

[0092] According to one embodiment, an electronic device is provided, the electronic device including: a waveguide configured to propagate a first light; a first lens; a second lens with the waveguide interposed between the first lens and the second lens; an optical coupler located on the waveguide, the optical coupler being configured to guide the first light out of the waveguide and through the second lens, and the first lens being configured to guide a second light through the optical coupler and the second lens; a curved coloring layer disposed between the first lens and the waveguide and configured to transmit the second light; a first air gap located between the curved coloring layer and the first lens; and a second air gap located between the curved coloring layer and the waveguide.

[0093] According to another embodiment, the curved coloring layer is electrically adjustable.

[0094] According to another embodiment, the curved coloring layer has a freeform curvature, a spherical curvature, an aspherical curvature, a one-dimensional curvature, or a two-dimensional curvature.

[0095] According to one embodiment, there is provided an electronic device including: a waveguide configured to propagate a first light; a first lens; a second lens, with the waveguide interposed between the first lens and the second lens; an optical coupler located on the waveguide, the optical coupler being configured to guide the first light out of the waveguide and through the second lens, and the first lens being configured to guide a second light through the optical coupler and the second lens; a third lens disposed between the first lens and the waveguide and configured to transmit the second light, the third lens having a planar surface facing the first lens and a curved surface facing the waveguide; a coloring layer located on the planar surface of the third lens; and an air gap located between the coloring layer and the first lens.

[0096] According to another embodiment, the coloring layer is electrically adjustable.

[0097] According to another embodiment, the electronic device includes an additional air gap located between the curved surface of the third lens and the waveguide.

[0098] According to another embodiment, the curved surface of the third lens has a freeform curvature, a spherical curvature, an aspherical curvature, a one-dimensional curvature, or a two-dimensional curvature.

[0099] According to one embodiment, there is provided an electronic device including: a waveguide configured to propagate a first light; a first lens; a second lens, with the waveguide interposed between the first lens and the second lens; an optical coupler located on the waveguide, the optical coupler being configured to guide the first light out of the waveguide and through the second lens, and the first lens being configured to guide a second light through the optical coupler and the second lens; and an electro-adjustable coloring layer configured to transmit the second light, the electro-adjustable coloring layer including: a first substrate having a first surface and a second surface opposite the first surface; a first anti-reflection coating located on the first surface; a first refractive index matching layer located on the second surface; a first electrode located on the first refractive index matching layer; a second substrate having a third surface and a fourth surface opposite the third surface; a second anti-reflection coating located on the fourth surface; a second refractive index matching layer located on the third surface; a second electrode located on the second refractive index matching layer; and an electrochromic gel located between the first electrode and the second electrode.

[0100] According to another embodiment, the first substrate and the second substrate are curved.

[0101] According to one embodiment, an electronic device is provided, the electronic device comprising: a waveguide configured to propagate a first light; a first lens; a second lens, the waveguide being interposed between the first lens and the second lens; an optical coupler located on the waveguide, the optical coupler being configured to direct the first light out of the waveguide and through the second lens, and the first lens being configured to direct a second light through the optical coupler and the second lens; a planar color layer disposed between the first lens and the waveguide and configured to transmit the second light toward the waveguide; an air gap located between the planar color layer and the waveguide; an adhesive coupling the color layer to the waveguide around the periphery of the air gap; and a set of spacers disposed within the air gap and coupling the planar color layer to the waveguide.

[0102] According to another embodiment, the planar color layer comprises: a first substrate; a second substrate; a chamber located between the first substrate and the second substrate; a peripheral seal coupling the first substrate to the second substrate around the chamber; an electrochromic gel disposed within the chamber; and an additional set of spacers disposed within the chamber and coupling the first substrate to the second substrate.

[0103] According to one embodiment, an electronic device is provided, the electronic device comprising: a waveguide configured to propagate a first light; a first lens; a second lens, the waveguide being interposed between the first lens and the second lens; an optical coupler located on the waveguide, the optical coupler being configured to direct the first light out of the waveguide and through the second lens, and the first lens being configured to direct a second light through the optical coupler and the second lens; and an electro - adjustable color layer configured to transmit the second light, the electro - adjustable color layer comprising: a first substrate; a second substrate; a chamber located between the first substrate and the second substrate; an adhesive ring coupling the first substrate to the second substrate around the lateral periphery of the cavity; an electrochromic gel disposed within the chamber; and a set of spacers disposed within the chamber and coupling the first substrate to the second substrate.

[0104] According to another embodiment, the set of spacers comprises epoxy beads.

[0105] According to one embodiment, there is provided an electronic device, the electronic device comprising: a waveguide configured to propagate a first light, the waveguide having a first surface and a second surface opposite the first surface; a first lens having a third surface facing the waveguide; a second lens having a fourth surface facing the waveguide, the waveguide being interposed between the first lens and the second lens; an optical coupler located on the waveguide, the optical coupler being configured to direct the first light out of the waveguide and through the second lens, and the first lens being configured to direct a second light through the optical coupler and the second lens; a coloring layer located on the third surface of the first lens; a first material layer contacting the coloring layer and the first surface of the waveguide; and a second material layer contacting the second surface of the waveguide and the fourth surface of the second lens.

[0106] According to another embodiment, the first material layer and the second material layer each have a refractive index between 1.0 and 1.5.

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

Claims

1. An electronic device, the electronic device comprises: a waveguide configured to propagate a first light; a first lens having a first surface facing the waveguide; a second lens with the waveguide interposed between the first lens and the second lens; an optical coupler located on the waveguide, wherein the optical coupler is configured to direct the first light out of the waveguide and through the second lens, and wherein the first lens is configured to direct a second light through the optical coupler and the second lens; a coloring layer located on the first surface of the first lens; and a third lens having a second surface located on the coloring layer and a third surface facing the waveguide, wherein the third lens is configured to transmit the second light to the optical coupler, and wherein the third surface is convex.

2. The electronic device according to claim 1, wherein the coloring layer is electrically adjustable.

3. The electronic device according to claim 1, wherein the first surface, the coloring layer, and the second surface are planar.

4. The electronic device according to claim 3, wherein the third surface is separated from the waveguide by an air gap.

5. The electronic device according to claim 3, wherein the third surface has a freeform curvature, a spherical curvature, an aspherical curvature, a one-dimensional curvature, or a two-dimensional curvature.

6. An electronic device, the electronic device comprises: a waveguide configured to propagate a first light and having a first planar surface and a second planar surface parallel to the first planar surface; a first lens having a third planar surface facing the waveguide, wherein the third planar surface is inclined at a non-parallel angle with respect to the first planar surface; a second lens with the waveguide interposed between the first lens and the second lens; an optical coupler located on the waveguide, wherein the optical coupler is configured to direct the first light out of the waveguide through the second planar surface and through the second lens, and wherein the first lens is configured to direct a second light through the optical coupler and the second lens; and a planar coloring layer located on the third planar surface of the first lens.

7. The electronic device according to claim 6, wherein the coloring layer is electrically adjustable.

8. The electronic device according to claim 6, the electronic device further comprises: a third lens having a fourth planar surface located on the coloring layer and parallel to the second planar surface, wherein the third lens is configured to transmit the second light to the optical coupler.

9. The electronic device according to claim 6, wherein the first lens has a surface opposite to the third planar surface, and the surface has a freeform curvature, a spherical curvature, an aspherical curvature, a one-dimensional curvature, or a two-dimensional curvature.

10. An electronic device, the electronic device comprises: a waveguide configured to propagate a first light; a first lens; A second lens, with the waveguide interposed between the first lens and the second lens; An optical coupler located on the waveguide, where the optical coupler is configured to direct the first light out of the waveguide and through the second lens, and where the first lens is configured to direct second light through the optical coupler and the second lens; A curved color layer disposed between the first lens and the waveguide and configured to transmit the second light; A first air gap located between the curved color layer and the first lens; And A second air gap located between the curved color layer and the waveguide.

11. The electronic device according to claim 10, wherein the curved color layer is electrically adjustable.

12. The electronic device according to claim 10, wherein the curved color layer has a free-form curvature, a spherical curvature, an aspherical curvature, a one-dimensional curvature, or a two-dimensional curvature.

13. An electronic device, the electronic device comprising: A waveguide configured to propagate first light; A first lens; A second lens, with the waveguide interposed between the first lens and the second lens; An optical coupler located on the waveguide, where the optical coupler is configured to direct the first light out of the waveguide and through the second lens, and where the first lens is configured to direct second light through the optical coupler and the second lens; A third lens disposed between the first lens and the waveguide and configured to transmit the second light, where the third lens has a planar surface facing the first lens and a curved surface facing the waveguide; A color layer located on the planar surface of the third lens; And An air gap located between the color layer and the first lens.

14. The electronic device according to claim 13, wherein the color layer is electrically adjustable.

15. The electronic device according to claim 13, the electronic device further comprising: An additional air gap located between the curved surface of the third lens and the waveguide.

16. The electronic device according to claim 13, wherein the curved surface of the third lens has a free-form curvature, a spherical curvature, an aspherical curvature, a one-dimensional curvature, or a two-dimensional curvature.

17. An electronic device, the electronic device comprising: A waveguide configured to propagate first light; A first lens; A second lens, with the waveguide interposed between the first lens and the second lens; An optical coupler located on the waveguide, where the optical coupler is configured to direct the first light out of the waveguide and through the second lens, and where the first lens is configured to direct second light through the optical coupler and the second lens; And An electrically adjustable color layer configured to transmit the second light, where the electrically adjustable color layer comprises: A first substrate having a first surface and a second surface opposite the first surface; A first antireflection coating, the first antireflection coating being located on the first surface; A first refractive index matching layer, the first refractive index matching layer being located on the second surface; A first electrode, the first electrode being located on the first refractive index matching layer; A second substrate, the second substrate having a third surface and a fourth surface opposite to the third surface; A second antireflection coating, the second antireflection coating being located on the fourth surface; A second refractive index matching layer, the second refractive index matching layer being located on the third surface; A second electrode, the second electrode being located on the second refractive index matching layer; and An electrochromic gel, the electrochromic gel being located between the first electrode and the second electrode.

18. The electronic device according to claim 17, wherein the first substrate and the second substrate are curved.

19. An electronic device, the electronic device comprising: A waveguide configured to propagate a first light; A first lens; A second lens, the waveguide being interposed between the first lens and the second lens; An optical coupler located on the waveguide, wherein the optical coupler is configured to guide the first light out of the waveguide and through the second lens, and wherein the first lens is configured to guide a second light through the optical coupler and the second lens; A planar coloring layer disposed between the first lens and the waveguide and configured to transmit the second light toward the waveguide; An air gap located between the planar coloring layer and the waveguide; An adhesive coupling the coloring layer to the waveguide around the periphery of the air gap; and A set of spacers disposed within the air gap and coupling the planar coloring layer to the waveguide.

20. The electronic device according to claim 19, wherein the planar coloring layer comprises: A first substrate; A second substrate; A chamber located between the first substrate and the second substrate; A peripheral seal coupling the first substrate to the second substrate around the chamber; An electrochromic gel disposed within the chamber; and An additional set of spacers disposed within the chamber and coupling the first substrate to the second substrate.

21. An electronic device, the electronic device comprising: A waveguide configured to propagate a first light; A first lens; A second lens, the waveguide being interposed between the first lens and the second lens; An optical coupler located on the waveguide, wherein the optical coupler is configured to guide the first light out of the waveguide and through the second lens, and wherein the first lens is configured to guide a second light through the optical coupler and the second lens; and An electro - adjustable coloring layer configured to transmit the second light, wherein the electro - adjustable coloring layer comprises: A first substrate; A second substrate; A chamber located between the first substrate and the second substrate; An adhesive ring that couples the first substrate to the second substrate around the lateral periphery of the chamber; An electrochromic gel disposed within the chamber; and A set of spacers disposed within the chamber and coupling the first substrate to the second substrate.

22. The electronic device according to claim 21, wherein the set of spacers includes epoxy beads.

23. An electronic device, the electronic device comprising: A waveguide configured to propagate a first light, wherein the waveguide has a first surface and a second surface opposite the first surface; A first lens having a third surface facing the waveguide; A second lens having a fourth surface facing the waveguide, the waveguide being interposed between the first lens and the second lens; An optical coupler located on the waveguide, wherein the optical coupler is configured to direct the first light out of the waveguide and through the second lens, and wherein the first lens is configured to direct a second light through the optical coupler and the second lens; A coloring layer located on the third surface of the first lens; A first material layer contacting the coloring layer and the first surface of the waveguide; and A second material layer contacting the second surface of the waveguide and the fourth surface of the second lens.

24. The electronic device according to claim 23, wherein the first material layer and the second material layer each have a refractive index between 1.0 and 1.5.

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