Waveguide, optical combiner, and eyewear display

Abstract

The waveguide includes a first substrate including an exit pupil expander and a separate second substrate including an output coupler. The first substrate and the second substrate overlap each other and are separated by a partition element. One or more facets direct light from the first substrate to the second substrate after exit pupil expansion so that the output coupler can output-couple the light.

Description

Background Art

[0001] In an augmented reality (AR) or mixed reality (MR) eyewear display, light from an image source is generally coupled by an input light coupling (i.e., input coupler) that can be formed on the surface of a light guide substrate or disposed within the substrate, which is also known as a light guide or waveguide. Once the light beam is coupled within the waveguide, the light beam is typically "guided" through the substrate by multiple total internal reflections (TIR) and then directed out of the waveguide by an output light coupling (i.e., "output coupler"). In some cases, another optical component known as an exit pupil expander is disposed in the optical path between the input coupler and the output coupler to expand the light beam in at least one dimension. The light beam projected from the waveguide by the output coupler overlaps at an eye relief distance from the waveguide to form an exit pupil, within which a user of the eyewear display can view a virtual image generated by the image source.

Summary of the Invention

[0002] In a first embodiment, the waveguide includes a first substrate that includes an exit pupil expander. The waveguide also includes a second substrate that overlaps the first substrate, and the second substrate includes an output coupler.

[0003] In some aspects of the first embodiment, the waveguide includes one or more facets that direct light from the first substrate to the second substrate. In some aspects of the first embodiment, the one or more facets include reflective facets that include a mirror coating. In some aspects of the first embodiment, the one or more facets include a diffraction grating or a holographic grating. In some aspects of the first embodiment, the waveguide includes a partition element between the first substrate and the second substrate. In some aspects of the first embodiment, the partition element has a refractive index lower than that of the first substrate and the second substrate. In some aspects of the first embodiment, the partition element includes a void. In some aspects of the first embodiment, the partition element includes a solid material. In some aspects of the first embodiment, the partition element includes a polarization beam splitter. In some aspects of the first embodiment, the exit pupil expander expands light in a first direction, and the output coupler outputs and couples light from the waveguide in a second direction different from the first direction. In some aspects of the first embodiment, the first direction is orthogonal to the second direction. In some aspects of the first embodiment, the first substrate overlaps the second substrate when viewed from the direction in which the output coupler outputs and couples light from the waveguide.

[0004] In the second embodiment, the optical combiner includes a first lens layer and a second lens layer, and a waveguide is disposed between the first lens layer and the second lens layer. The waveguide includes a first substrate that includes an exit pupil expander. The waveguide also includes a second substrate that overlaps the first substrate, and the second substrate includes an output coupler.

[0005] In some aspects of the second embodiment, the waveguide includes one or more facets that direct light from the first substrate to the second substrate. In some aspects of the second embodiment, the waveguide includes a partition element disposed between the first substrate and the second substrate. In some aspects of the second embodiment, the partition element has a refractive index lower than that of the first substrate and the second substrate. In some aspects of the second embodiment, the partition element includes a polarization beam splitter.

[0006] In the third embodiment, the eyewear display includes one or more lenses including an optical combiner. The optical combiner includes a waveguide. The waveguide includes a first substrate including an exit pupil expander. The waveguide also includes a second substrate overlapping the first substrate, and the second substrate includes an output coupler.

[0007] In some aspects of the third embodiment, the optical combiner includes a first lens layer and a second lens layer, and the waveguide is disposed between the first lens layer and the second lens layer. In some aspects of the third embodiment, the waveguide includes one or more facets that direct light from the first substrate to the second substrate, and a partition element between the first substrate and the second substrate. In some aspects of the third embodiment, the partition element has a lower refractive index than the first substrate and the second substrate. In some aspects of the third embodiment, the eyewear display includes a frame that holds one or more lenses.

[0008] By referring to the accompanying drawings, the present disclosure can be better understood, and its many features and advantages can become apparent to those skilled in the art. The use of the same reference symbols in different drawings indicates similar or identical items.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] The lenses of an AR / MR eyewear display with a form factor of an eyeglass frame generally have a relatively small field of view (FOV) area for projecting an image generated by an image source of the eyewear display. For example, in a conventional eyewear display of this type, the FOV area is typically on the order of about 10°×10° in the horizontal and vertical directions. In some cases, it may be advantageous to increase the size of the FOV area so that a user can recognize an image over a larger area of the lens of the eyewear display. Enlarging the FOV area generally involves increasing the size of an output coupler in a waveguide and the size of a corresponding exit pupil expander (EPE). However, since the available space in a conventional waveguide is limited, increasing the sizes of both the EPE and the output coupler in the waveguide using conventional techniques is not practical because the interference between the two components increases. For example, increasing the size of the EPE in a waveguide substrate reduces the available space in the waveguide substrate for enlarging the output coupler. FIGS. 1-10 present a technique for increasing the FOV area of an eyewear display by mounting the EPE and the output coupler on separate substrates of the waveguide. Thus, each of the EPE and the output coupler can be enlarged without interfering with each other.

[0011] For example, in some embodiments, the waveguide includes an input coupler and an EPE on a first substrate and an output coupler on a second substrate. In some embodiments, the first substrate and the second substrate are included in a stack of overlapping layers. The waveguide also includes a partition element or layer disposed between the first and second substrates and a set of reflective facets for directing light from the first substrate through or around the partition element to the second substrate. The partition element ensures that light propagating within the EPE of the first substrate does not interfere with the light propagating at the output coupler of the second substrate, and vice versa. The set of reflective facets is arranged to direct light from the first substrate to the second substrate such that after the light passes through the EPE, the light can also pass through the output coupler. In some embodiments, the partition element includes a material having a refractive index lower than the refractive indices of the materials of the first and second substrates. By disposing the EPE and the output coupler on different overlapping substrates, both the EPE and the output coupler can be expanded within the waveguide without interfering with each other. Thus, the size of the FOV area of the eyewear display can be increased, thereby allowing the user to view an image generated over a wider display area of the eyewear display.

[0012] In FIGS. 1-10, devices and techniques for increasing the virtual image display area by increasing the FOV area of an eyewear display are shown, as described in more detail below. The disclosed devices and techniques are described with respect to an exemplary display system, but it should be understood that the present disclosure is not limited to implementation in this particular display system and can be implemented in any of a variety of display systems using the guidelines provided herein.

[0013] Figure 1 shows an exemplary eyewear display 100 according to various embodiments. The eyewear display 100 (also referred to as a wearable head-up display (WHUD), a head-mounted display (HMD), a near-eye display, etc.) has a support structure 102 that includes an arm 104 which houses a microdisplay projection system configured to project an image toward the user's eyes, whereby the user recognizes the image projected as being displayed in the field of view (FOV) area 106 of the display at one or both of the lens elements 108, 110. In the illustrated embodiment, the support structure 102 of the eyewear display 100 is configured to be worn on the user's head and has the general shape and appearance of an eyeglass frame (i.e., form factor). The support structure 102 houses or includes various components to facilitate the projection of such an image toward the user's eyes, such as an image source (also referred to as a light engine, an optical engine, a projector, etc.), a waveguide (e.g., as shown in FIG. 2). In some embodiments, the support structure 102 further includes various sensors, such as one or more front cameras, rear cameras, other light sensors, motion sensors, accelerometers. The support structure 102 can further include one or more radio frequency (RF) interfaces or other wireless interfaces, such as a Bluetooth (trademark) interface, a WiFi interface. In some embodiments, the support structure 102 further includes a processing circuit or a control circuit for performing functions of the eyewear display 100, such as, for example, an eye-tracking function. Further, in some embodiments, the support structure 102 includes one or more batteries or other portable power sources for powering the electrical components of the eyewear display 100. In some embodiments, some or all of these components of the eyewear display 100 are fully or partially housed within the internal volume of the support structure 102, such as within the arm 104 in the vine region 112 of the support structure 102 or within the nose bridge 114 of the support structure 102.Although an exemplary form factor is shown, it should be noted that in other embodiments, the eyewear display 100 may have a shape and appearance different from the eyeglass frame shown in FIG. 1.

[0014] One or both of the lens elements 108, 110 are used by the eyewear display 100 to provide an AR or MR display, in which the rendered graphic content is overlaid on the real-world scene recognized by the user through the lens elements 108, 110 or provided in conjunction with the real-world scene. In some embodiments, one or both of the lens elements 108, 110 include a first lens layer and a second lens layer, and a waveguide is disposed between these layers. In some embodiments, one or both of the lens elements 108, 110 function as a light combiner that combines ambient light (also called peripheral light) from outside the eyewear display 100 and light emitted from the image source of the eyewear display 100. For example, the light used to form a recognizable image or series of images may be projected onto the user's eye by the image source of the eyewear display 100 through a series of optical elements such as a waveguide at least partially formed in the corresponding lens element, one or more scan mirrors, one or more light relays, and / or one or more prisms. In some embodiments, a plurality of image sources are included in the support structure 102. In some cases, the plurality of image sources are disposed in the temple region 112, the nose bridge, or a combination of two regions (e.g., one image source in the temple region 112 and another image source in the nose bridge region). In some embodiments, the waveguide includes a layered stack comprising a first substrate including an input coupler and EPE and a second substrate including an output coupler. In some embodiments, a partition element is disposed between the two substrates to ensure that the TIR condition is maintained for the light propagating through each of the two substrates. Further, a set of facets is included at or near one end of both substrates to direct the light from the first substrate to the second substrate (e.g., by reflection) after the light has passed through the EPE, thereby enabling the light to be directed to the output coupler.Accordingly, one or both of the lens elements 108, 110 include at least a portion of the waveguide that sends the display light received by the input coupler of the waveguide through the EPE of the waveguide to the output coupler, and the output coupler outputs the display light toward the eyes of the user of the eyewear display 100. The display light is modulated and projected onto the user's eyes such that the user perceives the display light as an image within the FOV area 106. Additionally, each of the lens elements 108, 110 is sufficiently transparent so that the user can see through the lens element, providing a view of the user's real-world environment, whereby the image appears superimposed over at least a portion of the real-world environment.

[0015] In some embodiments, each of one or more image sources is any combination of a matrix-based projector, a scanning laser projector, or a modulated light source such as a laser or one or more LEDs, and a dynamic reflector mechanism such as one or more dynamic scanners or digital light processors. In some embodiments, the image source includes, for example, a plurality of laser diodes (e.g., red laser diodes, green laser diodes, and / or blue laser diodes), and at least one scanning mirror (e.g., two one-dimensional scanning mirrors that are microelectromechanical system (MEMS)-type or piezoelectric). The image source is communicatively coupled to a controller and a non-transitory processor-readable storage medium or memory that stores processor-executable instructions and other data that, when executed by the controller, cause the controller to control the operation of the image source. In some embodiments, the controller is communicatively coupled to a processor (not shown) that controls the scan area size and scan area position of the image source and generates the content to be displayed on the eyewear display 100. The image source scans light over a specified FOV area 106, which is a variable area of the eyewear display 100. The scan area size corresponds to the size of the FOV area 106, and the scan area position corresponds to an area of one of the lens elements 108, 110 where the FOV area 106 is visible to the user. Generally, it is desirable for the display to have a wide FOV area to accommodate the output coupling of light over a wide angular range. As used herein, the range of different user eye positions from which the display can be viewed is referred to as the eyebox of the eyewear display 100.

[0016] The techniques and apparatus described herein increase the FOV area 106 of the waveguide within the form factor constraints imposed by the eyewear display 100. In some embodiments, the waveguide incorporated into one or each of the lens elements 108, 110 is made from a stack of layers including two separate substrate layers. The input coupler and EPE are embedded within or on the first of the two substrate layers, and the output coupler is embedded within or on the second of the two substrate layers. By placing the EPE and the output coupler on different substrate layers, each of the EPE and the output coupler can be expanded without potentially reducing the space for expanding the other. In this way, the FOV area 106 can be increased overall. This increases the area in which the image generated by the eyewear display 100 can be presented to the user.

[0017] FIG. 2 shows a diagram of a projection system 200 that projects display light representing an image onto a user's eye 222 via a waveguide 210 of an eyewear display, such as the eyewear display 100 shown in FIG. 1. The projection system 200 includes an image source 202, an optical scanner 220, and a waveguide 210. In FIG. 2, for clarity, one image source 202 and a corresponding optical scanner 220 are shown, but in some embodiments, multiple image sources 202 and optical scanners 220 are included in the projection system 200.

[0018] In some embodiments, the image source 202 includes one or more laser light sources configured to generate and output laser light (e.g., visible laser light such as red, blue, and green laser light, and / or non-visible laser light such as infrared laser light). In some embodiments, the image source 202 is coupled to a controller or driver (not shown), and the controller or driver controls the timing of the emission of display light from the light sources of the image source 202 (e.g., according to instructions received by the controller or driver from a computer processor coupled thereto) to modulate the display light 218 such that it is recognized as an image when output to the retina of the user's eye 222.

[0019] In some embodiments, the optical scanner 220 includes a first scan mirror 204, a second scan mirror 206, and an optical relay 208. Optionally, one or both of the scan mirrors 204 and 206 are MEMS mirrors. For example, the scan mirror 204 and the scan mirror 206 are MEMS mirrors that are driven by respective operating voltages to vibrate during the active operation of the laser projection system 200, and scan the display light 218 onto the scan mirror 204 and the scan mirror 206 toward the input coupler 212 of the waveguide 210.

[0020] The waveguide 210 of the projection system 200 includes an input coupler 212, an EPE 214, and an output coupler 216. As used herein, the term "waveguide" means a combiner that uses total internal reflection (TIR) or a combination of TIR, special filters, and / or reflective surfaces to transmit light from an input coupler through an EPE and to a corresponding output coupler. In display applications, for example, the light represents a collimated image, and the waveguide transmits and replicates the collimated image to the eye. Generally, the terms "input coupler", "exit pupil expander (or simply "EPE")", and "output coupler" refer to any type of optical grating structure including, but not limited to, diffraction gratings, tilted gratings, blazed gratings, holograms, holographic optical elements (e.g., optical elements using one or more holograms), volume diffraction gratings, volume holograms, surface relief diffraction gratings, and / or surface relief holograms. In some embodiments, a given input coupler, EPE, or output coupler is configured as a transmissive diffraction grating that transmits light through the input coupler, EPE, or output coupler and applies a designed optical function(s) to the light during that transmission. In some embodiments, a given input coupler, EPE, or output coupler is a reflective diffraction grating that reflects light off the input coupler, EPE, or output coupler and applies a designed optical function(s) to the light during that reflection. In this example, the display light 218 received by the input coupler 212 is expanded one-dimensionally (e.g., in a direction in or out of the plane of the paper as shown in FIG. 2) and relayed to the EPE 214, which directs the light to the output coupler 216 by TIR within the waveguide 210. The display light is then output as light 224 (labeled as a single beam for clarity) through the output coupler 216 to the user's eye 222.

[0021] In some embodiments, the EPE 214 receives light from the input coupler 212 and expands the light one-dimensionally in an eyebox of an eyewear display (such as one corresponding to the eyewear display 100) that houses the projection system 200. In some embodiments, the EPE 214 includes a one-dimensional diffraction grating that expands the light in this way. After expanding the light one-dimensionally, the EPE 214 sends the light to the output coupler 216. After receiving the light from the EPE 214, the output coupler 216 expands the light two-dimensionally and output-couples the light 224 to the user's eye 222. Thus, in some embodiments, the size of the output coupler 216 corresponds to an area where the user can recognize an image generated by the image source 202. In other words, the size of the output coupler 216 corresponds to the size of the FOV area (such as the FOV area 106 shown in FIG. 1) of the eyewear display equipped with the projection system 200.

[0022] FIG. 2 shows, for clarity of explanation, the optical components of the waveguide 210, namely, the input coupler 212, the EPE 214, and the output coupler 216, in order from right to left, and shows the propagation path of light in the waveguide. In some embodiments, the configurations of the input coupler 212, the EPE 214, and the output coupler 216 are different from those shown in FIG. 2. For example, in some embodiments, the waveguide 210 consists of a layered stack that includes the input coupler 212 and the EPE 214 on a first substrate of the layered stack and the output coupler 216 on a second substrate of the layered stack. In some embodiments, the waveguide 210 also includes a partition element (not shown in FIG. 2) between the first substrate and the second substrate and a reflective facet (not shown in FIG. 2) that directs light from the first substrate to the second substrate.

[0023] Figure 3 shows an example of a portion of an eyewear display 300 having a form factor of an eyeglass frame with a limited FOV 306, as specified by some embodiments. For example, the FOV 306 is within a range of approximately 10°×10° in the horizontal and vertical directions because the space available for incorporating a conventional waveguide is limited in the lens 308. As shown in Figure 3, the components of the waveguide include an input coupler 312, an EPE 314, and an output coupler 316. In Figure 3, the input coupler 312 is disposed in the temple region of the support structure of the eyewear display 300. The EPE 314 is disposed partially in the temple region and partially in the lens 308, while the output coupler 316 is disposed entirely in the lens 308 and corresponds to the FOV area 306. Thus, increasing the FOV area 306 includes increasing the size of the output coupler 316, which also requires expanding the size of the EPE 314. However, since the space available in the lens 308 is limited, increasing the sizes of the EPE 314 and the output coupler 316 according to conventional techniques is generally not possible due to the problems shown in Figures 4 and 5.

[0024] Figures 4 and 5 illustrate the problems when expanding the FOV area by conventional techniques. Figure 4 shows an example where the input coupler 412 is disposed in the vine region of the support structure. Figure 5 shows an example where the input coupler 512 is disposed in the nose bridge region of the support structure. In either case, a larger output coupler (output coupler 416 in Figure 4 and output coupler 516 in Figure 5 respectively) and a larger EPE (EPE 414 in Figure 4 and EPE 514 in Figure 5 respectively) are required to provide a wider FOV area in each of the respective lenses 408, 508. However, as the sizes of the output coupler and the EPE increase, the interference 420 and 520 between the two within the waveguide substrate becomes significantly larger, as shown in Figures 4 and 5 respectively. These interferences 420 and 520 result in a conflict between the function of the EPE (i.e., expanding the display light in the first dimension) and the function of the output coupler (i.e., expanding the display light in a second dimension different from the first dimension and output-coupling the light to the user). This conflict cannot be resolved without degrading the quality of the image delivered to the user, even by adjusting either or both of the EPE or the output coupler. Therefore, conventional techniques for widening the FOV area of the waveguide are severely limited by the form factor of the lenses and / or the eyeglass frame in this type of eyewear display.

[0025] Figure 6 shows an enlarged view of a waveguide 600 according to various embodiments. The waveguide 600 includes a stack of components or layers including a first substrate 602 and a second substrate 604. In some embodiments, the waveguide 600 also includes a partition element 622.

[0026] In some embodiments, the first substrate 602 and the second substrate 604 are made of the same material. For example, in some embodiments, each of the first substrate 602 and the second substrate 604 is made of a transparent or translucent material (such as plastic, polymer, glass, etc.) having optical properties that enable the function of the AR / MR eyewear display. In other embodiments, the first substrate 602 and the second substrate 604 are made of different waveguide materials. The first substrate 602 includes an input coupler 612 and an EPE 614 (such as the input coupler or EPE described in the previous figure), and the second substrate 604 includes an output coupler 616 (such as the output coupler described in the previous figure). As shown in the figure, the first substrate 602 and the second substrate 604 overlap each other. For example, the first substrate 602 and the second substrate 604 are included in a stack of components that form a waveguide 600 that overlaps each other in the z direction as shown in FIG. 6. In some embodiments, the term "overlap" with respect to the first substrate and the second substrate means that at least 50% of the first substrate coincides with the second substrate 604 along at least one axis (e.g., the z direction) as shown in FIG. 6 (and vice versa). That is, when viewed from the user side (i.e., the perspective of the user's eyes 222), at least 50% of the second substrate 604 overlaps the first substrate 602, or when viewed from the world side (i.e., the waveguide on the side opposite the user's eyes 222), at least 50% of the first substrate 602 overlaps the second substrate 604. In some embodiments, the term "overlap" with respect to the EPE 614 and the output coupler 616 means that each of these optical components (i.e., the EPE and the output coupler) performs its respective optical function in separate but adjacent planes (e.g., expanding the light beam along one dimension in the EPE). For example, referring to the waveguide 600 shown in FIG. 6, the EPE 614 expands the light beam in the plane corresponding to the first substrate 602, and the output coupler 616 expands the light beam in a separate but adjacent plane corresponding to the second substrate 604. In some embodiments, to facilitate the manufacture of the waveguide 600, the first substrate 602 and the second substrate 604 are entirely or mostly coincident with each other.That is, the first substrate and the second substrate completely or almost completely overlap each other, for example, with an overlap of 90% or more. In some embodiments, the dimensions of the first substrate 602 and the second substrate 604 are basically the same, and both substrates completely overlap each other so that, for example, their edges are not visible when observed by the user.

[0027] In some embodiments, the waveguide 600 includes a partition element 622 between the first substrate 602 and the second substrate 604. In some embodiments, the partition element is a void (or other gas-filled gap), a low refractive index material (i.e., a material having a refractive index lower than that of the material(s) of the first substrate 602 and the second substrate 604), or a polarization beam splitter (PBS). In any case, the partition element 622 serves as a barrier so that the light propagating in the EPE 614 and the light propagating in the output coupler 616 do not interfere with each other. For example, when the light of the EPE 614 is incident on the partition element 622 from the side of the first substrate 602, it propagates in the EPE 614 by TIR, and when the light of the output coupler 616 is incident on the partition element 622 from the side of the second substrate 604, it propagates in the output coupler 616 by TIR. Therefore, in some embodiments, the interfaces between the first substrate 602 and the partition element 622, and between the second substrate 604 and the partition element 622 enable TIR conditions for the light of the first substrate 602 and the light of the second substrate 604, respectively.

[0028] In some embodiments, waveguide 600 also includes a set of facets 632, 634. For example, a first facet 632 is disposed on a first substrate 602 and a second facet 634 is disposed on a second substrate 604. The set of facets 632, 634 direct light from the first substrate 602 to the second substrate 604. For example, after light passes through EPE 616 and is expanded in a first dimension / direction (e.g., along the y-dimension of FIG. 6), facet 632 directs the light from the first substrate 602 through or around partition element 622 to facet 634. In some embodiments, partition element 622 includes one or more holes or apertures 670 through which light can pass from the first facet 632 to the second facet 634. In some embodiments, facet 632 is arranged such that light incident thereon breaks the TIR condition of the first substrate 602, exits the first substrate 602, and is incident on facet 634. Facet 634 directs the light incident thereon by TIR within the second substrate 604 toward output coupler 616, expands it in a second dimension / direction (e.g., along the x-dimension of FIG. 6), and outputs it to be coupled to the user's eye 222. In some embodiments, the set of facets 632, 634 is any type of reflective surface such as a mirror or a metal layer. In some embodiments, the set of facets 632, 634 includes facets coated with a mirror coating or facets coated with a Bragg mirror coating. In other embodiments, the set of facets 632, 634 is a diffraction grating or a holographic grating.

[0029] By thus separating EPE 614 and output coupler 616 on different substrates, waveguide 600 can expand EPE 614 and output coupler 616 without interfering with each other. Thereby, by expanding the FOV area, an eyewear display equipped with waveguide 600 can provide an image generated over a wider display area (e.g., from an image source such as image source 202).

[0030] In some embodiments, light is sent through waveguide 600 according to the following path. First, the light is input-coupled at input coupler 612 and directed as input-coupled light 642 by TIR within the first substrate 602 toward the EPE 614. The EPE 614 expands the display light as EPE light 644 (labeled with a single arrow for clarity) in a first dimension (e.g., along the y-direction in FIG. 6). This light propagates within the EPE 614 by TIR through one partition element 622 and the outer surface of the other first substrate 602 (the front side in FIG. 6). When reaching the first facet 632, the light is directed out of the first substrate 602 as inter-substrate light 646 (labeled with a single dashed arrow for clarity). The inter-substrate light 646 passes through the partition element 622 or is directed around the partition element 622 and is incident on the second facet 634 of the second substrate 604. The second facet 634 directs the light incident thereon as second-substrate light 648 (labeled with a single arrow for clarity) into the second substrate by TIR through the outer surface of the second substrate (the far side in FIG. 6 facing the user's eye 222) and the partition element 622. The second-substrate light 648 is directed toward the output coupler 616, and the output coupler 616 expands the light in another dimension / direction and output-couples the light toward the user's eye 222 as output-coupled light 650.

[0031] Figures 7-9 show different embodiments of a waveguide, such as waveguide 600, with different types of partition elements disposed between two substrates, according to various embodiments. The optical propagation paths within and outside the waveguides of Figures 7-9 are indicated by dashed lines. As shown in Figures 7-9, the first substrate of each figure (e.g., the first substrate 702 in Figure 7, the first substrate 802 in Figure 8, and the first substrate 902 in Figure 9) overlaps with the second substrate of each figure (e.g., the second substrate 704 in Figure 7, the second substrate 804 in Figure 8, and the second substrate 904 in Figure 9). In this way, each corresponding EPE and output coupler can be expanded without restricting the size of the other. For example, referring to Figure 7, since the area of EPE 714 is on different planes in the z direction, it can be expanded along the x and y dimensions without interfering with the expansion of output coupler 716 along the x and y dimensions. Thus, the FOV area of the eyewear display with waveguide 700 in the lens element can be expanded. This also applies similarly to the waveguide configurations shown in Figures 8 and 9.

[0032] Referring to Figure 7, waveguide 700 includes a first substrate 702 with an input coupler 712 and an EPE 714. As shown in Figure 7, EPE 714 expands light in and out of the figure, i.e., along the y direction. Waveguide 700 also includes a second substrate 704 with an output coupler 716. Waveguide 700 further includes a set of facets 732, 734 for directing light from the first substrate 702 to the second substrate 704. The partition element shown in waveguide 700 is the gap 722 (or other gas-filled gap) between the first substrate 702 and the second substrate 704. Thus, light propagates within the first substrate 702 by TIR at the outer surface 742 of the first substrate 702 and the interface 744 between the first substrate 702 and the gap 722. Similarly, light propagates within the second substrate 704 by TIR at the outer surface 746 of the second substrate 704 and the interface 748 between the second substrate 704 and the gap 722. The light propagating within the second substrate 704 is emitted from the second substrate 704 by the output coupler 716.

[0033] Referring to FIG. 8, waveguide 800 includes a first substrate 802 with an input coupler 812 and an EPE 814. As shown in FIG. 8, the EPE 814 expands light in and out of the figure, i.e., along the y direction. Waveguide 800 also includes a second substrate 804 with an output coupler 816. Waveguide 800 further includes a set of facets 832, 834 for directing light from the first substrate 802 to the second substrate 804. The partition element shown in waveguide 800 is a low refractive index material 822 between the first substrate 802 and the second substrate 804. The low refractive index material 822 has a lower refractive index than each of the materials of the first substrate 802 and the second substrate 804. Thus, light propagates within the first substrate 802 by TIR at the outer surface 842 of the first substrate 802 and the interface 844 between the first substrate 802 and the low refractive index material 822. Similarly, light propagates within the second substrate 804 by TIR at the outer surface 846 of the second substrate 804 and the interface 848 between the second substrate 704 and the low refractive index material 822. The light propagating within the second substrate 804 is emitted from the second substrate 804 by the output coupler 816.

[0034] Referring to FIG. 9, waveguide 900 includes a first substrate 902 with an input coupler 912 and an EPE 914. As shown in FIG. 9, the EPE expands light inside / outside the figure, i.e., along the y direction. The waveguide also includes a second substrate 904 with an output coupler 916. Waveguide 900 further includes a set of facets 932, 934 for directing light from the first substrate 902 to the second substrate 904. The partition element shown in waveguide 800 is a polarization beam splitter (PBS) layer 922 between the first substrate 902 and the second substrate 904. The type of material of the PBS layer 922 is selected to reflect the type of polarization of the light propagating through the waveguide. For example, in some embodiments, the display light emitted from an image source input-coupled into waveguide 900 is p-polarized. Accordingly, the PBS layer 922 is configured to reflect light in the p-polarized state. In another embodiment, the display light emitted from an image source input-coupled into waveguide 900 may be s-polarized. In this case, the PBS layer 922 is configured to reflect light in the s-polarized state. In either case, the light propagates by TIR while reflecting within the first substrate 902 between the outer surface 942 of the first substrate 902 and the PBS layer 922 on the opposite side of the first substrate 902. Similarly, the light propagates by TIR while reflecting within the second substrate 904 between the outer surface 946 of the second substrate 904 and the PBS layer 922 on the opposite side of the second substrate 904. The light propagating within the second substrate 904 is emitted from the second substrate 904 by the output coupler 916.

[0035] FIG. 10 shows an optical combiner 1000 according to various embodiments. For example, the optical combiner 1000 may correspond to one or both of the lens elements 108, 110 of FIG. 1.

[0036] In some embodiments, the optical combiner 1000 combines the ambient light (also referred to as peripheral light) from the world side 1030 with the light emitted from an image source (such as the image source 202 in FIG. 2), so that the user's eyes 222 can recognize the image from the image source overlaid on the real-world environment. Accordingly, the optical combiner 1000 includes a first lens layer 1010 and a second lens layer 1020, and a waveguide 1015 is disposed therebetween. In some embodiments, the first lens layer 1010 and the second lens layer 1020 are transparent or translucent so that the peripheral light from the environment can reach the user's eyes 222. In some embodiments, the waveguide 1015 corresponds to any one of the waveguides 600, 700, 800, or 900 respectively shown in FIGS. 6-9. Accordingly, the waveguide 1015 of the optical combiner 1000 includes an enlarged output coupler, whereby the optical combiner 1000 can display an image over a wider area observed by the user's eyes 222.

[0037] Not all of the operations or elements described above in the general description are required, and some particular operations or parts of the device may not be required. It should be noted that in addition to those described, one or more additional operations may be performed or elements may be included. Further, the order in which the operations are listed is not necessarily the order in which they are performed. Also, the concepts are described with reference to specific embodiments. However, those skilled in the art will understand that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the following claims. Accordingly, the specification and drawings should be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure.

[0038] Advantages, other advantages, and solutions to problems are described above with respect to specific embodiments. However, no advantage, advantage, solution to a problem, or any feature(s) that may give rise to or make more prominent any advantage, advantage, or solution shall be construed as a critical, required, or essential feature of any or all of the claims. Further, since the disclosed subject matter may be modified and practiced in different but equivalent forms apparent to those skilled in the art having the benefit of the teachings herein, the specific embodiments disclosed above are illustrative only. No limitation with respect to the details of construction or design shown herein is intended other than as described in the following claims. Accordingly, the specific embodiments disclosed above may be varied or modified and it is evident that all such variations are within the scope of the disclosed subject matter. Therefore, the protection sought herein is as set forth in the following claims.

Claims

1. A first substrate including an exit pupil expander, and a second substrate overlapping with the first substrate, the second substrate including an output coupler, a waveguide.

2. The waveguide according to claim 1, further including one or more facets for directing light from the first substrate to the second substrate.

3. The waveguide according to claim 2, wherein the one or more facets include reflective facets including a mirror coating.

4. The waveguide according to claim 2, wherein the one or more facets include a diffraction grating or a holographic grating.

5. The waveguide according to claim 1, further including a partition element between the first substrate and the second substrate.

6. The waveguide according to claim 5, wherein the partition element has a refractive index lower than that of the first substrate and the second substrate.

7. The waveguide according to claim 5, wherein the partition element includes a void.

8. The waveguide according to claim 5, wherein the partition element includes a solid material.

9. The waveguide according to claim 5, wherein the partition element includes a polarization beam splitter.

10. The waveguide according to claim 1, wherein the exit pupil expander expands light in a first direction, and the output coupler outputs and couples light from the waveguide in a second direction different from the first direction.

11. The waveguide according to claim 10, wherein the first direction is orthogonal to the second direction.

12. The waveguide according to claim 1, wherein the first substrate overlaps with the second substrate when viewed from the direction in which the output coupler outputs and couples light from the waveguide.

13. A first lens layer and a second lens layer, and a waveguide disposed between the first lens layer and the second lens layer, wherein the waveguide includes a first substrate including an exit pupil expander, and a second substrate overlapping with the first substrate, the second substrate including an output coupler, an optical combiner.

14. The optical combiner according to claim 13, wherein the waveguide includes one or more facets for directing light from the first substrate to the second substrate.

15. The waveguide according to claim 13, wherein the waveguide includes a partition element disposed between the first substrate and the second substrate.

16. The optical combiner according to claim 15, wherein the partition element has a refractive index lower than that of the first substrate and the second substrate.

17. The optical combiner according to claim 13, wherein the partition element includes a polarization beam splitter.

18. Comprising one or more lenses including an optical combiner, The optical combiner includes a waveguide, and the waveguide, A first substrate including an exit pupil expander, An eyewear display including a second substrate overlapping the first substrate, the second substrate including an output coupler.

19. The optical combiner further includes a first lens layer and a second lens layer, and the waveguide is disposed between the first lens layer and the second lens layer. The eyewear display according to claim 18.

20. The waveguide, One or more facets for directing light from the first substrate to the second substrate, An eyewear display according to claim 18, comprising a partition element between the first substrate and the second substrate.

21. The eyewear display according to claim 18, wherein the partition element has a refractive index lower than that of the first substrate and the second substrate.

22. The eyewear display according to claim 18, further comprising a frame for holding the one or more lenses.

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