Method and system for dual projector waveguide displays with wide field of view

Abstract

To provide an augmented reality display system with an extended field of view in comparison with conventional systems.SOLUTION: An eyepiece waveguide comprises a substrate having a first surface and a second surface and a diffractive input coupling element. The diffractive input coupling element is configured to receive an input beam of light and to couple the input beam into the substrate as a guided beam. The eyepiece waveguide also comprises a diffractive combined pupil expander-extractor (CPE) element formed on or in the first surface or the second surface of the substrate. The diffractive CPE element includes a first portion and a second portion divided by an axis. A first set of diffractive optical elements is disposed in the first portion and oriented at a positive angle with respect to the axis, and a second set of diffractive optical elements is disposed in the second portion and oriented at a negative angle with respect to the axis.SELECTED DRAWING: Figure 3F

Description

[Technical Field]

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 029,312, filed May 22, 2020, and entitled "METHOD AND SYSTEM FOR DUAL PROJECTOR WAVEGUIDE DISPLAYS WITH WIDE FIELD OF VIEW," the entire contents of which are incorporated herein by reference in their entirety for all purposes. [Background technology]

[0002] Modern computing and display technology has facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally reproduced images, or portions thereof, are presented to a viewer in such a manner that they appear or can be perceived as real. Virtual reality, or "VR," scenarios typically involve the presentation of digital or virtual image information without transparency to other actual, real-world visual input, while augmented reality, or "AR," scenarios typically involve the presentation of digital or virtual image information as an extension to the visualization of the real world around the viewer.

[0003] Despite the advances made in these display technologies, there remains a need in the art for improved methods, systems, and devices relating to augmented reality systems, and particularly display systems. Summary of the Invention [Means for solving the problem]

[0004] The present invention relates generally to methods and systems relating to projection display systems, including wearable displays. More specifically, embodiments of the present invention provide methods and systems that provide an extended field of view compared to conventional systems. The present invention is applicable to a variety of applications in computer vision and image display systems.

[0005] As described herein, the field of view of the eyepiece waveguide, also referred to as the eyepiece, is increased over conventional designs by using multiple projectors to create sub-displays that form a combined field of view.

[0006] According to an embodiment of the present invention, an eyepiece waveguide for an augmented reality display system is provided. The eyepiece waveguide includes a substrate having a first surface and a second surface. The eyepiece waveguide also includes a diffractive input coupling element formed on or within the first or second surface of the substrate. The diffractive input coupling element is configured to receive an input beam of light and couple the input beam of light into the substrate as a guided beam. The eyepiece waveguide further includes a diffractive combining pupil expander-extractor (CPE) element formed on or within the first or second surface of the substrate. The diffractive CPE element includes a first portion and a second portion separated by an axis. The first set of diffractive optical elements is disposed within the first portion and oriented at a positive angle relative to the axis, and the second set of diffractive optical elements is disposed within the second portion and oriented at a negative angle relative to the axis.

[0007] According to another embodiment of the present invention, an eyepiece waveguide for an augmented reality display system is provided. The eyepiece waveguide includes a substrate having a first surface and a second surface. The eyepiece waveguide also includes a first diffractive input coupling element formed on or within the first or second surface of the substrate. The first diffractive input coupling element is configured to receive a first input beam of light and couple the first input beam of light into the substrate as a first guided beam. The eyepiece waveguide further includes a second diffractive input coupling element formed on or within the first or second surface of the substrate. The second diffractive input coupling element is configured to receive a second input beam of light and couple the second input beam of light into the substrate as a second guided beam.

[0008] Additionally, the eyepiece waveguide includes a diffractive combining pupil expander-extractor (CPE) element formed on or within the first surface or the second surface of the substrate, positioned to receive the first guided beam from the first diffractive input coupling element, receive the second guided beam from the second diffractive input coupling element, outcouple at least a portion of the first guided beam over a first range of angles to form a first field of view of the combined field of view, and outcouple at least a portion of the second guided beam over a second range of angles to form a second field of view of the combined field of view.

[0009] According to a specific embodiment of the present invention, a waveguide display disposed within eyeglasses is provided. The waveguide display includes a first projector, a second projector, a first internal coupling grating (ICG) optically coupled to the first projector, and a second ICG optically coupled to the second projector. An axis passes through the first ICG and the second ICG. The waveguide display also includes a first diffractive region optically coupled to the first ICG, the first diffractive region including a first portion with a first set of gratings oriented at a positive angle relative to the axis, and a second portion with a second set of gratings oriented at a negative angle relative to the axis. The waveguide display further includes a second diffractive region optically coupled to the second ICG, the second diffractive region including a first portion with a third set of gratings oriented at a positive 180° angle relative to the axis, and a second portion with a fourth set of gratings oriented at a negative -180° angle relative to the axis.

[0010] According to certain embodiments of the present invention, a method of operating an eyepiece waveguide defined by a first region and a second region is provided. The method includes directing light from a first projector to impinge on a first internal coupling grating (ICG). The method also includes diffracting a percentage of the light from the first projector into a first portion of the first region of the eyepiece waveguide, into a first portion of the second region, into a second portion of the second region, and out of the eyepiece waveguide. The method further includes diffracting another percentage of the light from the first projector into a second portion of the first region of the eyepiece waveguide, into a second portion of the second region, into the first portion of the second region, and out of the eyepiece waveguide. In addition, the method includes directing light from a second projector to impinge on a second ICG. The method also includes diffracting a percentage of the light from the second projector into a first portion of the second region of the eyepiece waveguide, into a first portion of the first region, into a second portion of the first region, and out of the eyepiece waveguide. The method further includes diffracting another percentage of the light from the second projector into a second portion of the second region of the eyepiece waveguide, into a second portion of the first region, into a first portion of the first region, and out of the eyepiece waveguide.

[0011] Numerous benefits over conventional techniques are achieved by the methods of the present invention. For example, embodiments of the present invention provide methods and systems that can be used to increase the field of view of a display and improve the user experience. In certain embodiments, the grating period is selected to produce individual fields of view that are tiled or partially overlapping, producing a combined field of view. These and other embodiments of the present invention, along with many of their advantages and features, are described in further detail in the following text and in conjunction with the accompanying figures. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a simplified plan view illustrating an eyepiece waveguide, according to an embodiment of the present invention.

[0013] [Figure 2A] FIG. 2A is a simplified cross-sectional view illustrating an eyepiece waveguide with a reduced grating period, according to an embodiment of the present invention.

[0014] [Figure 2B] FIG. 2B is a simplified cross-sectional view illustrating an eyepiece waveguide with an increased grating period, according to an embodiment of the present invention.

[0015] [Figure 3A] FIG. 3A is a simplified plan view illustrating elements of an eyepiece waveguide with an increased grating period and combined field of view, according to an embodiment of the present invention.

[0016] [Figure 3B] FIG. 3B is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A with respect to a first set of rays forming a first portion of the field of view.

[0017] [Figure 3C] FIG. 3C is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A with respect to a second set of rays forming a second portion of the field of view.

[0018] [Figure 3D] FIG. 3D is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A with respect to the field of view.

[0019] [Figure 3E] FIG. 3E is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A for an alternate field of view.

[0020] [Figure 3F]FIG. 3F is a simplified plan view illustrating the eyepiece waveguide shown in FIG. 3A, along with exemplary light rays, in accordance with an embodiment of the present invention.

[0021] [Figure 3G] FIG. 3G is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A with respect to the combined field of view.

[0022] [Figure 4A] FIG. 4A is a simplified plan view illustrating a multi-projector waveguide display utilizing eyepiece waveguides with increased grating periods, according to an embodiment of the invention.

[0023] [Figure 4B] FIG. 4B is a simplified plan view illustrating the propagation of light rays from a second projector in the multi-projector waveguide display shown in FIG. 4A.

[0024] [Figure 4C] FIG. 4C is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 4A.

[0025] [Figure 4D] FIG. 4D is a simplified flowchart illustrating a method of operating an eyepiece waveguide defined by a first region and a second region, according to an embodiment of the present invention.

[0026] [Figure 5A] FIG. 5A is a simplified plan view illustrating a multi-projector waveguide display utilizing eyepiece waveguides with reduced grating periods, according to an embodiment of the invention.

[0027] [Figure 5B] FIG. 5B is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 5A.

[0028] [Figure 6A] FIG. 6A is a simplified plan view illustrating elements of a multi-projector waveguide display according to an embodiment of the invention.

[0029] [Figure 6B] FIG. 6B is a simplified plan view illustrating the propagation of light rays within a multi-projector waveguide display according to an embodiment of the present invention.

[0030] [Figure 7A] FIG. 7A is a simplified plan view illustrating a six-projector waveguide display according to an embodiment of the present invention.

[0031] [Figure 7B] FIG. 7B is a simplified plan view illustrating a single projector element of the six-projector waveguide display illustrated in FIG. 7A.

[0032] [Figure 7C] FIG. 7C is a simplified k-space diagram illustrating the operation of the single projector element shown in FIG. 7B.

[0033] [Figure 7D] FIG. 7D is a simplified k-space diagram illustrating the operation of the six-projector waveguide display shown in FIG. 7A.

[0034] [Figure 8] FIG. 8 is a simplified schematic diagram illustrating the integration of one or more eyepiece waveguides with eyeglasses, according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] Detailed Description of Specific Embodiments The present invention relates generally to methods and systems related to projection display systems, including wearable displays. More specifically, embodiments of the present invention provide methods and systems having an extended field of view compared to conventional systems. The present invention is applicable to a variety of applications in computer vision and image display systems and light field projection systems, including stereoscopic systems, systems that deliver beamlets of light to a user's retina, or the like.

[0036] FIG. 1 is a simplified plan view illustrating an eyepiece waveguide according to an embodiment of the present invention. As illustrated in FIG. 1, eyepiece waveguide 100 includes a first internal coupling grating (ICG) 110 and a second ICG 120. A combined pupil expander-extractor (CPE) element 130 is disposed between first ICG 110 and second ICG 120. Eyepiece waveguide 100 can achieve an extended field of view that may be greater than the range of propagation angles that can be supported by propagation modes guided through the thickness of the waveguide. As illustrated in FIGS. 2A and 2B, eyepiece waveguide 100 has a first surface 132 and a second surface 134. As discussed further below, different diffractive features can be formed on or within opposing surfaces 132 and 134 of eyepiece waveguide 100.

[0037] The first ICG 110 receives a set of input beams 112 from a first projector 150 (shown in FIG. 2A ), and the second ICG 120 receives a set of input beams 122 from a second projector 160 (also shown in FIG. 2A ). In some embodiments, the input beams can propagate through free space from the projectors until they are incident on one of the ICGs. As shown in FIG. 1 , the set of input beams 112 incident on ICG 110 and the set of input beams 122 incident on ICG 120 are angled or tilted with respect to the z-axis. The ICGs 110 and 120 diffract the input beams such that some (possibly all) of the input beams enter guided propagation modes within the eyepiece waveguide 100. The grating lines of the ICGs 110 and 120 can be oriented to direct the diffracted beams along the x-axis toward the CPE 130.

[0038] The CPE 130 can include multiple diffractive features exhibiting periodicity along multiple axes. Thus, the CPE 130 may consist of an array of scattering features arranged in a 2D grid pattern. Individual scattering features can be, for example, depressions or protrusions of any shape. The 2D array of scattering features has an associated lattice vector, which is derived from the reciprocal lattice pattern of the 2D grid pattern. As an example, the CPE 130 can be a 2D diffraction grating consisting of a crossed grid, with grating lines repeated along two or more directions of periodicity. The diffractive features that make up the CPE 130 can have a relatively low diffraction efficiency (e.g., 10% or less). This low diffraction efficiency therefore allows beams of light to be replicated in a manner that is spatially dispersed in multiple directions as they propagate through the CPE 130.

[0039] FIG. 2A is a simplified cross-sectional view illustrating an eyepiece waveguide with a reduced grating period, according to an embodiment of the present invention. The design illustrated in FIG. 2A results in high efficiency because light incident on one side of the eyepiece waveguide is preferentially outcoupled onto the same side of the eyepiece waveguide, thereby providing high efficiency because the light is not lost during propagation across the eyepiece waveguide but is outcoupled after a short propagation path. Furthermore, image clarity is maintained because the propagation distance and the number of TIR reflections are reduced. As illustrated in FIG. 2A, the grating period, which is inversely proportional to the grating pitch measured between the grating teeth, is selected so that rays of a set of input beams 122 of a given wavelength incident on the ICG 120 at an angle above zero (i.e., tilted at a positive angle relative to the z-axis) are incoupled along a direction centered on the negative x-axis. For this grating with a reduced grating period and increased grating pitch, if light at a given wavelength is incident at normal incidence, the light will be incoupled along a direction tilted upward at a positive angle relative to the negative x-axis. Therefore, the reduced grating period utilizes a weaker incoupling grating than conventional designs. In other words, if a range of in-waveguide angles is associated with incoupling for a range of angles centered on normal incidence, the grating period will be reduced so that a range of angles tilted at a positive angle relative to the z-axis will be incoupling into the same range of in-waveguide angles.

[0040] Thus, the angular cone defined by rays 122 inclined at angles ranging from 0° to +50° with respect to the z-axis is incoupled into the eyepiece waveguide 101 and suffers TIR as the angular cone propagates down the waveguide. To project light incident at a non-normal angle, projector 160 can be tilted with respect to the eyepiece waveguide, optics can be utilized to introduce the non-normal incidence angle from a projector oriented normal to the eyepiece waveguide, or the like.

[0041] In the embodiment illustrated in FIG. 2A , the external coupling grating 136 has a grating period that matches the grating period of the ICG 120. Thus, a cone 123 of angles ranging from 0° to 50° relative to the z-axis is outcoupled from the eyepiece waveguide 101. In other words, if a range of intra-waveguide angles is propagating within the eyepiece waveguide 101, the grating period of the external coupling grating 136 will be reduced so that a range of angles tilted at positive angles relative to the z-axis will be outcoupled from the same range of intra-waveguide angles. While the internal and external couplings are illustrated on opposite surfaces of the eyepiece waveguide 101, this is not required by the present invention; the internal and external couplings can also occur from the same surface.

[0042] Similarly, the grating period of the incoupling grating 110 is selected so that rays of an input beam 112 of a given wavelength incident on the ICG 110 at angles less than zero (i.e., tilted at a negative angle relative to the z-axis) are incoupled along a direction centered on the positive x-axis. For this grating with a reduced grating period and increased grating pitch, if light at a given wavelength is incident at normal incidence, the light will be incoupled along a direction tilted upward at a positive angle relative to the x-axis. Thus, the angular cone defined by rays 112 tilted at angles ranging from 0° to −50° relative to the z-axis is incoupled into the eyepiece waveguide 101 and suffers TIR as the angular cone propagates down the waveguide. To project light incident at a non-normal angle, projector 150 can be tilted relative to the eyepiece waveguide, optics can be utilized to introduce the non-normal incidence angle from a projector oriented normal to the eyepiece waveguide, or the like.

[0043] 2A, the outer coupling grating 138 has a grating period that matches the grating period of the inner coupling grating 110. Thus, a cone 113 of angles ranging from 0° to −50° relative to the z-axis is outcoupled from the eyepiece waveguide 101. Although the inner and outer couplings are illustrated on opposite surfaces of the eyepiece waveguide 101, this is not required by the present invention, and the inner and outer couplings can occur from the same surface.

[0044] 2A, by utilizing two projectors, the two fields of view produced by projector 150 and projector 160 are thus biased at a predetermined angle relative to the normal to the eyepiece waveguide, resulting in the illustrated tiled field of view, i.e., combined field of view 102. Thus, embodiments of the present invention utilize a waveguide in which the carrying capacity of the waveguide (i.e., based on the TIR angle) is fully utilized in conjunction with off-normal incident light and a modification of the grating period from conventional designs to produce a tiled field of view.

[0045] Thus, using a design characterized by a reduced grating period, light injected into an ICG positioned on one side of the eyepiece waveguide is preferentially coupled out onto the same side of the eyepiece waveguide to form a sub-display of a combined field of view. As shown in FIG. 2A , light ray 122, which defines an angular cone tilted at an angle ranging from 0° to 50° with respect to the z-axis, is coupled inward into eyepiece waveguide 101 and coupled out as a ray within angular cone 123, forming a first sub-display covering an angular range from 0° to 50° with respect to the z-axis. In parallel, light ray 112, which defines an angular cone tilted at an angle ranging from 0° to -50° with respect to the z-axis, is coupled inward into eyepiece waveguide 101 and coupled out as a ray within angular cone 113, forming a second sub-display covering an angular range from 0° to -50° with respect to the z-axis. A combined field of view 102 is formed by tiling the first sub-display and the second sub-display to form a combined field of view 102 equal to 100°, covering an angular range of -50° to 50°.

[0046] By utilizing a polymer eyepiece waveguide material, including a polymer with a refractive index of approximately 1.75, conventional eyepiece waveguide designs can achieve a field of view of approximately 50°. By utilizing an eyepiece waveguide with an increased grating period, as illustrated in FIG. 2A, a combined field of view of up to 100° can be achieved in a tiled configuration using symmetric projector tilt to produce a tilt in the incident angle and a matching increase in grating period for the in-coupling and out-coupling gratings, resulting in a symmetric tilt and tiled field of view of the output light. Alternatively, a combined field of view ranging from 50° to 100° can also be achieved in a partially overlapping configuration.

[0047] While Figure 2A illustrates light being incoupled into the eyepiece waveguide at a given angle and outcoupled from the eyepiece waveguide at a given angle, this is not required by the present invention. In other embodiments, the grating periods of the incoupling grating and outcoupling grating are modified to allow for incoupling of a first angle cone centered on the first angle and outcoupling of a second angle cone centered on a second angle different from the first angle. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0048] The structure of the grating utilized in the embodiment illustrated in FIG. 2A can be varied in different regions of the eyepiece waveguide. In this design, with a reduced grating period, a blazed grating can be used to increase the outcoupling efficiency. As an example, grating 136 can be blazed to increase its efficiency for light received from projector 160, and grating 138 can be blazed to increase its efficiency for light received from projector 150. This blazed grating design would result in little light from projector 150 being outcoupled by grating 136 and little light from projector 160 being outcoupled by grating 138. In the central region between gratings 136 and 138, the grating structure can be stepped, starting with one blazed grating profile, followed by a binary grating in the central region, and ending with another blazed grating profile. In addition to blazed gratings, other diffractive surfaces, particularly surfaces characterized by different diffraction efficiencies depending on the direction of incident light, can also be utilized, including metasurfaces and metamaterials, volume phase holograms, stepped gratings, and the like. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0049] FIG. 2B is a simplified cross-sectional view illustrating an eyepiece waveguide with an increased grating period, according to an embodiment of the present invention. The design illustrated in FIG. 2B results in light incident on one side of the eyepiece waveguide being preferentially outcoupled onto the opposite side of the eyepiece waveguide. Using a design with an increased grating period, the spatial separation between the in-coupling grating and the out-coupling grating is reduced, providing room for the image size to expand and allowing the size of the eyepiece waveguide to be reduced. As illustrated in FIG. 2B, the grating period, which is inversely proportional to the grating pitch measured between the grating teeth, is selected so that light rays 122 of a given wavelength incident on the ICG 154 at an angle above zero (i.e., tilted at a positive angle relative to the z-axis) are incoupled along a direction centered on the positive x-axis. For the present gratings with increased grating period and decreased grating pitch, if light at a given wavelength is incident at normal incidence, the light will be incoupled along a direction tilted upward at a positive angle relative to the positive x-axis. The increased grating period therefore utilizes a stronger incoupling grating than conventional designs. Thus, the angular cone defined by light rays 122 tilted at angles ranging from 0° to +50° relative to the z-axis is incoupled into the eyepiece waveguide 104 and suffers TIR as the angular cone propagates down the waveguide. To project light incident at a non-normal angle, the projector 160 can be tilted relative to the eyepiece waveguide, or an optical system can be utilized to introduce the non-normal incidence angle from a projector oriented normal to the eyepiece waveguide, or the like.

[0050] 2B, the outcoupling grating 156 has a grating period that matches the grating period of the ICG 154. Thus, a cone 123 of angles ranging from 0° to 50° relative to the z-axis is outcoupled from the eyepiece waveguide 104. Although the incoupling and outcoupling are illustrated on opposite surfaces of the eyepiece waveguide 104, this is not required by the present invention, and the incoupling and outcoupling can occur from the same surface.

[0051] Similarly, the grating period of the internal coupling grating (ICG) 164 is selected so that light rays 112 of a given wavelength incident on the ICG 164 at angles less than zero (i.e., tilted at a negative angle relative to the z-axis) are incoupled along a direction centered on the negative x-axis. For this grating with increased grating period and decreased grating pitch, light at a given wavelength, when incident at normal incidence, will be incoupled along a direction tilted upward at a positive angle relative to the negative x-axis. Thus, the angular cone defined by light rays 112 tilted at angles ranging from 0° to −50° relative to the z-axis is incoupled into the eyepiece waveguide 104 and suffers TIR as the angular cone propagates down the waveguide. To project light incident at a non-normal angle, projector 150 can be tilted relative to the eyepiece waveguide, optics can be utilized to introduce the non-normal incidence angle from a projector oriented normal to the eyepiece waveguide, or the like.

[0052] 2B, the outer coupling grating 166 has a grating period that matches the grating period of the inner coupling grating 164. Thus, a cone 113 of angles ranging from 0° to −50° relative to the z-axis is outcoupled from the eyepiece waveguide 104. Although the inner and outer couplings are illustrated on opposite surfaces of the eyepiece waveguide 104, this is not required by the present invention, and the inner and outer couplings can occur from the same surface.

[0053] 2B, by utilizing two projectors, the two fields of view produced by projector 150 and projector 160 are thus biased at a predetermined angle relative to the normal to the eyepiece waveguide, resulting in the illustrated tiled field of view, i.e., combined field of view 105. Thus, embodiments of the present invention utilize a waveguide in which the carrying capacity of the waveguide (i.e., based on the TIR angle) is fully utilized in conjunction with off-normal incident light and a modification of the grating period from conventional designs to produce a tiled field of view.

[0054] Thus, using a design characterized by an increased grating period, light launched at an ICG positioned on one side of the eyepiece waveguide propagates to the other side of the eyepiece waveguide, where it is outcoupled to form a sub-display of the combined field of view. As shown in FIG. 2B, light ray 122, which defines a cone of angles tilted at an angle ranging from 0° to 50° with respect to the z-axis, is incoupled into eyepiece waveguide 104 and outcoupled as light ray 123, forming a first sub-display covering an angular range from 0° to 50° with respect to the z-axis. In parallel, light ray 112, which defines a cone of angles tilted at an angle ranging from 0° to -50° with respect to the z-axis, is incoupled into eyepiece waveguide 104 and outcoupled as light ray 113, forming a second sub-display covering an angular range from 0° to -50° with respect to the z-axis. A combined field of view 105 is formed by tiling the first sub-display and the second sub-display to form a combined field of view 105 equal to 100°, covering an angular range of -50° to 50°.

[0055] By utilizing a polymer eyepiece waveguide material, including a polymer with a refractive index of approximately 1.75, conventional eyepiece waveguide designs can achieve a field of view of approximately 50°. By utilizing an eyepiece waveguide with an increased grating period, as illustrated in FIG. 2B, a combined field of view of up to 100° can be achieved in a tiled configuration using symmetric projector tilt to produce a tilt in the incident angle and a matching increase in grating period for the in-coupling and out-coupling gratings, resulting in a symmetric tilt and tiled field of view of the output light. Alternatively, a combined field of view ranging from 50° to 100° can also be achieved in a partially overlapping configuration.

[0056] While Figure 2B illustrates light being incoupled into the eyepiece waveguide at a given angle and outcoupled from the eyepiece waveguide at a given angle, this is not required by the present invention. In other embodiments, the grating periods of the incoupling grating and outcoupling grating are modified to allow for incoupling of a first angle cone centered on the first angle and outcoupling of a second angle cone centered on a second angle different from the first angle. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0057] The structure of the grating utilized in the embodiment illustrated in FIG. 2B can be varied in different regions of the eyepiece waveguide. In this design, with an increased grating period, a blazed grating can be used to increase the outcoupling efficiency. As an example, grating 156 can be blazed to increase its efficiency for light received from projector 160, and grating 166 can be blazed to increase its efficiency for light received from projector 150. This blazed grating design would result in little light from projector 150 being outcoupled by grating 156 and little light from projector 160 being outcoupled by grating 166. In the central region between gratings 156 and 166, the grating structure can be stepped, starting with one blazed grating profile, followed by a binary grating in the central region, and ending with another blazed grating profile. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0058] FIG. 3A is a simplified plan view illustrating elements of an eyepiece waveguide with an increased grating period and a combined field of view, according to an embodiment of the present invention. In FIG. 3A, the propagation and diffraction of light rays within the waveguide display are illustrated, along with the resulting field of view. As illustrated in FIG. 3A, diffraction of input light by ICG 305 results in light being diffracted into and propagating within the plane of the waveguide, as illustrated by rays 311 and 315. As will be explained, the light ray represented by ray 311 and the light ray represented by ray 315 will result in the generation of field of view 310 (illustrated in FIG. 3D), which includes first portion 310a and second portion 310b.

[0059] After diffraction from ICG 305, ray 311 propagates upward and to the right and diffracts from the grating in the upper portion of the waveguide, producing ray 312, which propagates downward and to the right. This OPE diffraction event is represented by arrow 322 in FIG. 3B. Ray 312 propagates within the waveguide and diffracts from the grating in the lower portion of the waveguide, producing outcoupling event 313. Outcoupled ray 314 is shown propagating upward from the lower portion of the waveguide toward the user, thereby producing a first portion 310a of field of view 310, which is associated with the lower portion of the user's field of view.

[0060] In parallel, ray 315 propagates downward and to the right near axis 301 and diffracts from a grating in the lower portion of the waveguide near axis 301, producing ray 316, which propagates upward and to the right. This OPE diffraction event is represented by arrow 332 in FIG. 3C . Ray 316 propagates within the waveguide and diffracts from a grating in the upper portion of the waveguide near axis 301, producing outcoupling event 317. Outcoupled ray 318 is shown propagating downward from the upper portion of the waveguide near axis 301 toward the user, thereby producing lower portion 310b of field of view 310.

[0061] Thus, field of view 310 includes a first portion 310a associated with light ray 311 and a second portion 310b associated with light ray 315. As will be apparent to one skilled in the art, light rays that are intercoupled at intermediate angles and operable to propagate within the waveguide will fill field of view 310.

[0062] 3B is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A with respect to a first set of rays forming a first portion of the field of view. As shown in FIG. 3B, a first portion 310a of the field of view 310 progresses through the k-space diagram, as represented by positions 326 and 328, such that it is not limited by the boundaries of the annulus defined by the circle located at n=1.0 and the circle located at n=1.75, which correspond to the angles within the waveguide. Diffraction within and out of the plane of the eyepiece waveguide thus results in progression through the k-space diagram through regions propagating inside the eyepiece waveguide.

[0063] Referring to Figure 3B, diffraction from ICG 305 is represented by arrow 320, which represents a grating vector that translates first portion 310a of the field of view into the intra-waveguide region of the k-space diagram, as illustrated by location 326. An OPE diffraction event resulting from ray 311, which diffracts to produce ray 312 as illustrated in Figure 3A, is represented by arrow 322 in Figure 3B, which translates first portion 310a of the field of view from location 326 in the intra-waveguide region of the k-space diagram to location 328, also within the intra-waveguide region of the k-space diagram. An EPE outcoupling event 313 resulting from ray 312, which diffracts to produce outcoupled ray 314, is represented by arrow 324 in Figure 3B, which translates first portion 310a of the field of view from location 328 in the intra-waveguide region of the k-space diagram to the eye space region of the k-space diagram associated with first portion 310a of the field of view.

[0064] Thus, as shown by the k-space diagram illustrated in FIG. 3B, the light within the lower portion of the user's field of view is formed by rays propagating upward from the lower portion of the waveguide toward the user, thereby producing a first portion 310a of the field of view 310.

[0065] The k-space diagram in FIG. 3B demonstrates that the eyepiece waveguide design illustrated in FIG. 3A has a grating spacing that is characterized by an increased grating period along axis 302 because the center of field of view 310a is translated as a result of OPE and EPE diffraction events over a distance measured along axis 302 that exceeds the distance from the origin to the position along axis 302 at which the center of field of view, represented by position 328, is located. In other words, with reference to FIG. 3B, distance L measured along axis 302 exceeds distance D. By way of comparison, considering the magnitude of translation along axis 301, the distance from the origin to point 303 is equal to the distance the center of field of view 310a is translated along axis 301 because the grating spacing along axis 301 is not characterized by an increased or decreased grating period.

[0066] Thus, using an eyepiece waveguide design including grating lines oriented at approximately 60° relative to one another, light can flow within the k-space diagram along three different grating vectors: arrow 320, which represents diffraction by the ICG into the plane of the eyepiece waveguide and represents a grating vector aligned with axis 301, translating field of view 310a to position 326; arrow 322, which represents a grating vector oriented at approximately −120° relative to axis 301, translating the field of view at position 326 to position 328; and arrow 324, which represents a grating vector oriented at approximately 60° relative to axis 301, translating the field of view at position 328 to field of view 310a. Because positions 326 and 328 are within the annulus of an angle within the waveguide, light diffracted along these three different grating vectors will be maintained within the eyepiece waveguide.

[0067] FIG. 3C is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A with respect to a second set of rays forming a second portion of the field of view. Referring to FIG. 3A, ray 315, after diffraction from ICG 305, propagates downward and to the right near axis 301, ultimately resulting in the generation of outcoupled ray 318. As shown in FIG. 3C, diffraction from ICG 305 is represented by arrow 330, which translates second portion 310b of the field of view into the intra-waveguide region of the k-space diagram, as illustrated by position 336. The OPE diffraction event resulting from ray 315, which diffracts to produce ray 315 as shown in FIG. 3A, is represented by arrow 332 in FIG. 3C, which translates second portion 310b of the field of view from position 336 within the intra-waveguide region of the k-space diagram to position 338, also within the intra-waveguide region of the k-space diagram. An EPE outcoupling event 317 resulting from ray 316, which diffracts to produce outcoupled ray 318, translates second portion 310b of the field of view from a position 338 within the intra-waveguide region of the k-space diagram to an eye space region of the k-space diagram associated with second portion 310b of the field of view, represented by arrow 334 in FIG. 3C.

[0068] 3B, the second portion 310b of the field of view 310 progresses through the k-space diagram, as represented by positions 336 and 338, such that it is not limited by the boundaries of the annulus defined by the circle located at n=1.0 and the circle located at n=1.75, which correspond to the intra-waveguide angles. Diffraction within and out of the plane of the eyepiece waveguide thus results in progression through the k-space diagram through regions propagating inside the eyepiece waveguide.

[0069] FIG. 3D is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A with respect to the field of view. In the k-space diagram shown in FIG. 3D, a first portion 310a and a second portion 310b of the field of view 310 are shown. As discussed in connection with FIGS. 3A-3C, light rays diffracted by ICG into the waveguide and propagating to the right and generally upward and downward at a small angle relative to the axis 301 can be represented in k-space by translation to positions 326 and 336 of the field of view 310, which represent propagation within the waveguide. OPE interactions, represented by arrows 322 and 332, represent propagation from the upper portion of the waveguide to the lower portion of the waveguide and from the lower portion of the waveguide to the upper portion of the waveguide, respectively. Finally, EPE interactions are represented by outcoupling, represented by the field of view 310 at an angle within the eye space region.

[0070] Thus, field of view 310 includes a first portion 310a associated with light ray 311 and a second portion 310b associated with light ray 315. As will be apparent to one skilled in the art, light rays that are intercoupled at intermediate angles and operable to propagate within the waveguide will fill field of view 310.

[0071] Figure 3E is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in Figure 3A with respect to an alternate field of view. In Figure 3E, field of view 340, associated with the lower portion of the user's field of view, is formed as light propagates downward from the upper portion of the waveguide toward the user. Field of view 340 is therefore a mirror image of field of view 310 relative to axis 301.

[0072] Referring to Figure 3E, a first portion 340a and a second portion 340b of the field of view 340 are shown. In a manner similar to, and mirror-image of, the operation shown in connection with Figures 3A-3D, light rays diffracted by the ICG into the waveguide, propagating at a small angle to the right and generally downward and upward relative to the axis 301, can be represented in k-space by translations to positions 346 and 356 of the field of view 340, representing propagation within the waveguide. OPE interactions result in translations of the first portion to position 348 and the second portion to position 358, respectively, as these intra-waveguide propagation angles are supported by the waveguide. Finally, EPE interactions are represented by outcoupling, represented by the field of view 340 at angles within the eye space region.

[0073] Thus, as a mirror image of field of view 310, field of view 340 includes a first portion 340a associated with light rays propagating downward and to the right in Figure 3A, and a second portion 340b associated with light rays propagating upward and to the right in Figure 3A. As will be apparent to one skilled in the art, light rays that are intercoupled at intermediate angles and operable to propagate within the waveguide will fill field of view 340.

[0074] FIG. 3F is a simplified plan view illustrating the eyepiece waveguide shown in FIG. 3A along with exemplary light rays, according to an embodiment of the present invention. Representative light rays associated with both the first and second portions of fields of view 310 and 340 are illustrated in FIG. 3F. As discussed in connection with FIG. 3A, light ray 311 propagates upward and to the right after diffraction from ICG 305 and diffracts from the grating in the upper portion of the waveguide, producing a ray that propagates downward and to the right (OPE interaction). When this ray interacts with the grating in the lower portion of the waveguide, an EPE event occurs, resulting in the outcoupling of light ray 314 to propagate upward from the lower portion of the waveguide toward the user, thereby producing first portion 310a of field of view 310. In parallel, ray 315 propagates downward and to the right near axis 301 and diffracts from a grating in the lower portion of the waveguide near axis 301, producing a ray that propagates upward and to the right (OPE interaction). When this ray interacts with a grating in the upper portion of the waveguide, an EPE event occurs, resulting in the outcoupling of ray 318 to propagate downward from the upper portion of the waveguide toward the user, thereby producing second portion 310b of field of view 310.

[0075] In a mirror-image fashion, ray 381 propagates downward and to the right and diffracts from the grating in the lower portion of the waveguide as an OPE diffraction event, producing ray 382, ​​which propagates upward and to the right. Ray 382 propagates within the waveguide and diffracts from the grating in the upper portion of the waveguide, producing outcoupling event 383. Outcoupled ray 384 is shown propagating downward from the upper portion of the waveguide toward the user, thereby producing a first portion 340a of field of view 340, which is associated with the upper portion of the user's field of view. In parallel, ray 385 propagates upward and to the right near axis 301 and diffracts from the grating in the upper portion of the waveguide near axis 301 as an OPE diffraction event, producing ray 386, which propagates downward and to the right. Ray 386 propagates within the waveguide and diffracts from a grating in the lower portion of the waveguide near axis 301, producing an outcoupling event 387. Outcoupled ray 388 is shown propagating upward from the lower portion of the waveguide near axis 301 toward the user, thereby producing a second portion 340b of field of view 340.

[0076] Thus, field of view 340 includes a first portion 340a associated with ray 381 and a second portion 340b associated with ray 385. As will be apparent to one skilled in the art, rays that are intercoupled at intermediate angles and operable to propagate within the waveguide will fill field of view 340.

[0077] Also, while only four OPE interactions and four EPE interactions are illustrated for clarity, it should be understood that rays 311 / 385 and 315 / 381 would experience OPE interactions throughout the top and bottom portions of the waveguide, respectively. Similarly, rays 312 / 386 and 316 / 382 would experience EPE interactions throughout the bottom and top portions of the waveguide, respectively. Thus, outcoupling events occur throughout the entire waveguide, and outcoupling events 313 / 387 and 317 / 383 are merely exemplary. As a result, outcoupled rays dispersed across the waveguide would contribute to generating fields of view 310 and 340.

[0078] Note that the gratings in the top and bottom portions of the waveguide intersect at axis 301 without overlap in the embodiment illustrated in FIG. 3F. However, this is not required by the present invention, and in some other embodiments, the gratings overlap at positions along axis 302 at predetermined distances above and / or below axis 301. This overlap region would allow light rays propagating into the top portion of the waveguide to undergo an OPE interaction with the grating, which occurs in the bottom portion of the waveguide, and extend into the top portion of the waveguide within the overlap region. Continuing with this example, light rays propagating into the top portion of the waveguide and undergoing an OPE interaction in the overlap region could diffract upward into the top portion and undergo an EPE interaction, which would result in an outcoupling event that would improve the power output associated with field of view 340. Similarly, light rays propagating into the bottom portion of the waveguide may undergo an OPE interaction with the grating occurring in the upper portion of the waveguide and extend into the bottom portion of the waveguide in the overlap region. These light rays propagating into the bottom portion of the waveguide and undergoing an OPE interaction in the overlap region may diffract downward into the bottom portion and undergo an EPE interaction, which may result in an outcoupling event that may improve the output associated with field of view 310.

[0079] 3A and 3F, a combined field of view is formed by the overlap of field of view 310 and field of view 340. Thus, while each field of view individually provides a field of view of approximately 50° by approximately 40° (i.e., vertical by horizontal), the overlapped fields of view provide a combined field of view of approximately 80° by approximately 40°, thereby significantly improving the user experience.

[0080] FIG. 3G is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 3A with respect to a combined field of view. Referring to FIG. 3G, combined field of view 350 is formed by the overlap between field of view 310 and field of view 340. The translation of field of view 310 to positions 360 and 361 is shown for clarity, but it should be understood that a portion of this field of view translates through position 366 in k-space. Similarly, the translation of field of view 340 to positions 365 and 366 is shown for clarity, but it should be understood that a portion of this field of view translates through position 361 in k-space. As shown in FIG. 3G, field of view 310 has a spatial extent of approximately 50° vertical by approximately 40° horizontal. Similarly, field of view 340 has a similar spatial extent. Due to the overlap between these fields of view, a combined field of view is formed, characterized by a much larger, expanded field of view of approximately 80° by approximately 40°. Thus, using embodiments of the present invention that utilize a single projector and a grating characterized by an increased grating period in one dimension, a waveguide display with an increased field of view is enabled.

[0081] 4A is a simplified plan view illustrating a multi-projector waveguide display 400 utilizing an eyepiece waveguide with an increased grating period, according to an embodiment of the present invention. In a manner similar to that discussed in connection with FIG. 2B, diffraction of input light by ICG 405 results in light being diffracted into and propagating within the plane of the waveguide, as illustrated by rays 411 and 415. As will be explained, the light ray represented by ray 411 and the light ray represented by ray 415 will each initially result in the generation of a field of view that includes two portions associated with the light rays propagating into the upper half of the eyepiece waveguide and the lower half of the eyepiece waveguide, respectively.

[0082] Multi-projector waveguide display 400 includes a first region 403, which is circular in this embodiment, and a second region 404, which is also circular in this embodiment. First region 403 and second region 404 overlap, forming overlap region 406. In FIG. 4A , overlap region 406 is located at the midpoint between ICG 405 and ICG 425. First region 403 includes a first portion defined by an upper semicircle of first region 403 and a second portion defined by a lower semicircle of first region 403. Similarly, second region 404 includes a first portion defined by an upper semicircle of second region 404 and a second portion defined by a lower semicircle of second region 404. Overlap region 406 is formed by the overlap of a first portion of the first region and a first portion of the second region, and the overlap of a second portion of the first region and a second portion of the second region. Additional discussion related to the eyepiece waveguides of a multi-projector waveguide display is provided in connection with FIG. 6A.

[0083] Ray 411, after diffraction from ICG 405, propagates upward and to the right and diffracts from the grating in the upper portion of the waveguide, producing ray 412, which propagates downward and to the right. Ray 412 propagates within the waveguide and diffracts from the grating in the lower portion of the waveguide, producing outcoupling event 413. Outcoupled ray 414 is shown propagating upward from the lower portion of the waveguide toward the user, thereby producing a portion of the field of view associated with the lower portion of the user's field of view.

[0084] In parallel, ray 415 propagates downward and to the right near axis 401 and diffracts off a grating in the lower portion of the waveguide near axis 401, producing ray 416, which propagates upward and to the right. Ray 416 propagates within the waveguide and diffracts off a grating in the upper portion of the waveguide near axis 401, producing outcoupling event 417. Outcoupled ray 418 is shown propagating downward from the upper portion of the waveguide near axis 401 toward the user, thereby producing the lower portion of the field of view. As will be apparent to those skilled in the art, rays incoupled at intermediate angles and operable to propagate within the waveguide will fill the field of view. Referring to FIG. 4C , field of view 410 is produced by rays illustrated by rays 411 and 415.

[0085] FIG. 4B is a simplified plan view illustrating the propagation of light rays from a second projector in the multi-projector waveguide display illustrated in FIG. 4A. As will be apparent to one skilled in the art, the operation of the eyepiece waveguide discussed in connection with FIG. 4B will, to some extent, mirror the operation of the eyepiece waveguide as discussed in connection with FIG. 4A. That is, diffraction of input light by ICG 425, occurring with a second projector (not shown), results in light being diffracted into and propagating within the plane of the waveguide, as illustrated by light rays 431 and 435. As will be explained, light rays represented by light rays 431 and 435 will each result in the generation of a field of view that includes two portions associated with light rays initially propagating into the upper half of the eyepiece waveguide and the lower half of the eyepiece waveguide, respectively.

[0086] Ray 431, after diffraction from ICG 425, propagates upward and to the left and diffracts from the grating in the upper portion of the waveguide, producing ray 432, which propagates downward and to the left. Ray 432 propagates within the waveguide and diffracts from the grating in the lower portion of the waveguide, producing outcoupling event 433. Outcoupled ray 434 is shown propagating upward from the lower portion of the waveguide toward the user, thereby producing a portion of the field of view associated with the lower portion of the user's field of view.

[0087] In parallel, ray 435 propagates downward and to the left near axis 401 and diffracts off a grating in the lower portion of the waveguide near axis 401, producing ray 436, which propagates upward and to the left. Ray 436 propagates within the waveguide and diffracts off a grating in the upper portion of the waveguide near axis 401, producing outcoupling event 437. Outcoupled ray 438 is shown propagating downward from the upper portion of the waveguide near axis 401 toward the user, thereby producing the lower portion of the field of view. As will be apparent to those skilled in the art, rays incoupled at intermediate angles and operable to propagate within the waveguide will fill the field of view. Referring to FIG. 4C , field of view 460 is produced by the rays illustrated by rays 431 and 435.

[0088] Figure 4C is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in Figure 4A. Referring to Figure 4C, a combined field of view containing four fields of view is formed by the overlap between fields of view 410 and 430 produced by light incident from the first projector and fields of view 460 and 470 produced by light incident from the second projector.

[0089] As illustrated in Figure 4C, each individual field of view has a spatial extent of approximately 50° vertical by approximately 40° horizontal. By combining four individual fields of view in a combined field of view, the overlap between these fields of view results in a combined field of view characterized by a much larger, expanded field of view of approximately 80° by approximately 100°. Thus, using embodiments of the present invention utilizing two projectors and a grating characterized by an increased grating period in two dimensions, a waveguide display with an increased or expanded field of view is enabled.

[0090] Referring to FIG. 4C , embodiments of the present invention provide a display with tiled fields of view formed by tiling multiple individual fields of view, with or without overlap between adjacent fields of view. As will be apparent to those skilled in the art, in this embodiment of an eyepiece waveguide fabricated in a polymer with a refractive index of 1.75, the annulus defined by the circle located at n=1.0 and the circle located at n=1.75 corresponds to the waveguide inter-angle. It should be understood that, in contrast to designs utilizing expensive and exotic materials such as sapphire and lithium niobate, embodiments of the present invention provide an eyepiece waveguide that can be fabricated in a low-cost, lightweight, and robust low-index material, such as polymer, while still providing a wide field of view within a combined field of view design. While some of the discussion herein relates to polymer materials, embodiments of the present invention are not limited to these materials, and the concepts discussed herein are also applicable to materials with a refractive index greater than 1.75. In particular, the annulus having a boundary at n=1.75 is not intended to limit the scope of the present invention. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

[0091] The k-space diagram in Figure 4C demonstrates that the eyepiece waveguide design illustrated in Figures 4A and 4B is characterized by an increased grating period along both axes 401 and 402 because the center of field of view 410 is translated over a distance along axes 401 and 402 that exceeds the distance from the origin to position 419 and from the origin to position 409. Thus, for the eyepiece waveguide design illustrated in Figures 4A and 4B and described by the k-space diagram in Figure 4C, the translation in k-space that corresponds to diffraction by ICG exceeds the distance from the origin to the center of the waveguide's intra-angle angle. That is, the distance in k-space from position 407 to position 409 (measured along axis 401) exceeds the distance in k-space from the origin to position 409 (measured along axis 401) (i.e., an increased grating period along axis 401), and the distance in k-space from position 407 to position 419 (measured along axis 402) exceeds the distance in k-space from the origin to position 419 (i.e., an increased grating period along axis 402).

[0092] As explained more fully in connection with FIG. 3G and illustrated in FIG. 4C, the diffraction of light into and out of the eyepiece waveguide and the propagation of light within the eyepiece waveguide result in several different translations of fields 410, 430, 460, and 470 within k-space. As illustrated in FIGS. 4A and 4C, light diffracted from ICG 405 will translate fields 410 and 430 into the right portion of the annulus of intra-waveguide angles. OPE diffraction events will translate these fields into the lower right and upper right portions of the annulus of intra-waveguide angles, respectively. Light diffracted from grating lines, acting as EPE events, will translate these fields to the positions illustrated for fields 410 and 430 within the eye space region of the k-space diagram.

[0093] As illustrated in Figures 4B and 4C, light diffracted from ICG 425 will translate fields 460 and 470 into the left portion of the annulus of intra-waveguide angles. OPE diffraction events will translate these fields into the lower left and upper left portions of the annulus of intra-waveguide angles, respectively. Light diffracted from grating lines, acting as EPE events, will translate these fields to the positions shown for fields 460 and 470 in the eye space region of the k-space diagram.

[0094] As shown in FIG. 4C, the center of each of the fields of view is offset from the origin of the k-space diagram. As discussed herein, the use of a grating with an increased period in both directions results in this vertical and horizontal offset. As a result, by using two projectors, one providing image light to a first ICG and one providing image light to a second ICG, an extended field of view can be created by tiling the individual fields of view, with overlap between the individual fields of view defined by the grating characteristics.

[0095] Note that the description provided in connection with FIGS. 4A and 4B pertains to central rays that would be associated with the central pixel of the projected image frame. In addition, rays that form at the edges of the image frame can be analyzed using the formalism utilized above in connection with FIGS. 4A and 4B. These rays may be referred to as peripheral rays. As will be apparent to those skilled in the art, propagation within the k-space diagram is inversely proportional to propagation within image space, with propagation within the upper portion of the k-space diagram corresponding to propagation within the lower portion of image space. As illustrated in FIGS. 4A-4C, rays that are coupled out of the bottom portion of the eyepiece waveguide along an upward direction, when clearly centered relative to the eyepiece waveguide, will be directed toward the eyebox in a manner suitable for reaching the user's pupil. Furthermore, rays that are coupled out of the top portion of the eyepiece waveguide along a downward direction, when clearly centered relative to the eyepiece waveguide, will be directed toward the eyebox in a manner suitable for reaching the user's pupil. Thus, embodiments of the present invention provide an efficient design in which light is outcoupled in a manner that preferentially reaches the user's pupil when the pupil is specifically centered within the eyebox.

[0096] By tracing peripheral rays associated with the top, bottom, and sides of the field of view of each image frame, the inventors demonstrate that light rays corresponding to the bottom of the field of view are efficiently outcoupled at the bottom of the eyepiece waveguide, with reduced or minimal outcoupling at the top of the eyepiece waveguide. Thus, light efficiency in reaching the eyebox and pupil of the user's eye is increased by embodiments of the present invention because outcoupling events are increased and / or maximized for light from the projector providing light to ICG 405 that outcouples from the bottom of the eyepiece waveguide along an upward direction directed toward the eyebox, and outcoupling events are increased and / or maximized for light from the projector providing light to ICG 425 that outcouples from the top of the eyepiece waveguide along a downward direction directed toward the eyebox.

[0097] FIG. 4D is a simplified flowchart illustrating a method of operating an eyepiece waveguide defined by a first region and a second region according to an embodiment of the present invention. The method illustrated in FIG. 4D can be implemented in the context of a multi-projector waveguide display utilizing the eyepiece waveguides illustrated in FIGS. 4A and 4B. Method 480 includes a step (482) of directing light from a first projector to impinge on a first internal coupling grating (ICG). The first projector, illustrated as projector 621 in FIG. 6A, can project light that impinges on the first ICG, illustrated as ICG 405 in FIG. 4A or ICG 620 in FIG. 6A.

[0098] Light incident on the first ICG is diffracted into the plane of the eyepiece waveguide, and a percentage of the light from the first projector is diffracted into a first portion of the first region of the eyepiece waveguide, into a first portion of the second region, into a second portion of the second region, and out of the eyepiece waveguide (484). Referring to Figure 4A, light diffracted into the first portion of the first region 403 of the eyepiece waveguide passes without diffraction into the first portion of the second region 404, while in Figure 6A, light diffracted into the first portion 602 of the first region 601 of the eyepiece waveguide is diffracted in the plane of the eyepiece waveguide toward the first portion 605 of the second region 604. Thus, in some embodiments, a first portion of the first region of the eyepiece waveguide includes a first set of diffractive optical elements, e.g., a first set of gratings that are blazed and characterized by a reduced outcoupling efficiency for light from the first projector.

[0099] As light propagates within the first portion of the second region of the eyepiece waveguide, diffraction from a diffractive optical element, e.g., a grating, results in a redirection of the light toward the second portion of the second region 404, illustrated by ray 412 in FIG. 4A. The grating within the first portion of the second region can be oriented at approximately 150° with respect to an axis passing between ICG 405 and ICG 425. Additionally, ray 412 illustrated in FIG. 4A propagates within the waveguide and diffracts from the grating within the second portion of the second region, producing outcoupling out of the eyepiece waveguide. The grating within the second portion of the second region can be oriented at approximately −150° with respect to the axis passing between ICG 405 and ICG 425. As described in connection with FIG. 4A, the outcoupled light propagates upward from the second portion of the second region of the waveguide toward the user, thereby producing a portion of the field of view associated with the lower portion of the user's field of view.

[0100] Another percentage of light from the first projector is diffracted into a second portion of the first region of the eyepiece waveguide, into a second portion of the second region, into a first portion of the second region, and out of the eyepiece waveguide (486). Referring to FIG. 4A , light diffracted into the second portion of the first region 403 of the eyepiece waveguide passes without diffraction into the second portion of the second region 404, while in other embodiments, light diffracted into the second portion of the first region of the eyepiece waveguide is diffracted within the plane of the eyepiece waveguide toward the second portion of the second region. Thus, in some embodiments, the second portion of the first region of the eyepiece waveguide includes a second set of diffractive optical elements, e.g., a second set of gratings that are blazed and characterized by a reduced outcoupling efficiency for light from the first projector.

[0101] As light propagates within the second portion of the second region of the eyepiece waveguide, diffraction from a diffractive optical element, e.g., a grating, results in a redirection of the light toward the first portion of the second region 404, illustrated by ray 416 in FIG. 4A . The grating within the first portion of the first region can be oriented at approximately 30° with respect to an axis passing between ICG 405 and ICG 425. Additionally, ray 416 illustrated in FIG. 4A propagates within the waveguide and diffracts from the grating within the first portion of the second region 404, producing outcoupling out of the eyepiece waveguide. The grating within the second portion of the first region can be oriented at approximately −30° with respect to the axis passing between ICG 405 and ICG 425. As described in connection with FIG. 4A , the outcoupled light propagates downward from the first portion of the second region of the waveguide toward the user, thereby producing a portion of the field of view associated with the upper portion of the user's field of view.

[0102] The method also includes directing 488 light from the second projector to impinge on a second internal coupling grating (ICG). The second projector, illustrated as second projector 626 in Figure 6A, can project light that impinges on a second ICG, illustrated as ICG 425 in Figure 4A or ICG 625 in Figure 6A.

[0103] Light incident on the second ICG is diffracted into the plane of the eyepiece waveguide, and a percentage of the light from the second projector is diffracted into a first portion of the second region of the eyepiece waveguide, into a first portion of the first region, into a second portion of the first region, and out of the eyepiece waveguide (490). Referring to FIG. 4B, light diffracted into the first portion of the second region 404 of the eyepiece waveguide passes without diffraction into the second portion of the first region 403, while in other embodiments, light diffracted into the first portion of the second region of the eyepiece waveguide is diffracted within the plane of the eyepiece waveguide toward the first portion of the first region. Thus, in some embodiments, the first portion of the second region of the eyepiece waveguide includes a third set of diffractive optical elements, e.g., a third set of gratings that are blazed and characterized by a reduced outcoupling efficiency for light from the second projector.

[0104] As light propagates within the first portion of the first region of the eyepiece waveguide, diffraction from a diffractive optical element, e.g., a grating, results in a redirection of the light toward the second portion of the first region, illustrated by ray 432 in FIG. 4B. The grating within the first portion of the first region can be oriented at approximately 30° with respect to an axis passing between ICG 405 and ICG 425. Additionally, ray 432 illustrated in FIG. 4B propagates within the waveguide and diffracts from the grating within the second portion of the first region, producing outcoupling out of the eyepiece waveguide. The grating within the second portion of the first region can be oriented at approximately −30° with respect to the axis passing between ICG 405 and ICG 425. As described in connection with FIG. 4B, the outcoupled light propagates upward from the second portion of the first region of the waveguide toward the user, thereby producing a portion of the field of view associated with the lower portion of the user's field of view.

[0105] Another percentage of light from the second projector is diffracted into the second portion of the second region of the eyepiece waveguide, into the second portion of the first region, into the first portion of the first region, and out of the eyepiece waveguide (492). Referring to Figure 4B, light diffracted into the second portion of the second region of the eyepiece waveguide passes into the second portion of the first region without diffraction, while in other embodiments, light diffracted into the second portion of the second region of the eyepiece waveguide is diffracted within the plane of the eyepiece waveguide toward the second portion of the first region. Thus, in some embodiments, the second portion of the second region of the eyepiece waveguide includes a fourth set of diffractive optical elements, e.g., a fourth set of gratings that are blazed and characterized by a reduced outcoupling efficiency for light from the second projector.

[0106] As light propagates within the second portion of the first region of the eyepiece waveguide, diffraction from a diffractive optical element, e.g., a grating, results in a redirection of the light toward the first portion of the first region, as illustrated by ray 436 in FIG. 4B. The grating within the second portion of the first region can be oriented at approximately −30° with respect to the axis passing between ICG 405 and ICG 425. Additionally, ray 436 illustrated in FIG. 4B propagates within the waveguide and diffracts from the grating within the first portion of the first region, producing outcoupling out of the eyepiece waveguide. The grating within the first portion of the first region can be oriented at approximately 30° with respect to the axis passing between ICG 405 and ICG 425. As described in connection with FIG. 4B, the outcoupled light propagates downward from the first portion of the first region of the waveguide toward the user, thereby producing a portion of the field of view associated with the upper portion of the user's field of view.

[0107] In some embodiments, light from a first projector impinges on the first ICG at a first non-zero angle of incidence, and light from a second projector impinges on the second ICG at a second non-zero angle of incidence that is equal to zero minus the first non-zero angle of incidence. In these embodiments, a first field of view of a first portion of a second region is centered at the non-zero angle of incidence, and a second field of view of a first portion of a first region is centered at the non-zero angle of incidence.

[0108] It should be understood that the specific steps illustrated in FIG. 4D provide a particular method of operating an eyepiece waveguide defined by a first region and a second region according to an embodiment of the present invention. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the steps outlined above in a different order. Furthermore, individual steps illustrated in FIG. 4D may include multiple sub-steps that may be performed in various sequences, depending on the needs of the individual step. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0109] Figure 5A is a simplified plan view illustrating a multi-projector waveguide display utilizing an eyepiece waveguide with a reduced grating period, according to an embodiment of the invention. The description provided in connection with Figures 4A-4C is applicable to Figures 5A-5C, except for the eyepiece waveguide with a reduced grating period.

[0110] In this design, in which the grating period is reduced by increasing the grating pitch, light propagates a reduced distance along the eyepiece waveguide before being outcoupled. Referring to FIG. 5A, light incident on ICG 505 is outcoupled within field of view 510 of the eyepiece waveguide adjacent to ICG 505. Similarly, light incident on ICG 525 is outcoupled within field of view 530 of the eyepiece waveguide adjacent to ICG 525.

[0111] FIG. 5B is a simplified k-space diagram illustrating the operation of the eyepiece waveguide shown in FIG. 5A.

[0112] The k-space diagram in FIG. 5B demonstrates that the eyepiece waveguide design illustrated in FIG. 5A is a design characterized by a reduced grating period along axis 501 and an increased grating period along axis 502. The reduced grating period along axis 501 is illustrated by the center of field of view 510 / 560 being translated along axis 501 a distance that is less than the distance from the origin to the center of the annulus of the waveguide angle. Similarly, the center of field of view 530 / 570 is also translated along axis 501 a distance that is less than the distance from the origin to the center of the annulus of the waveguide angle. In the vertical direction aligned with axis 502, behavior similar to that discussed above in connection with FIG. 4C is demonstrated. Thus, the center of field of view 510 / 560 is translated along axis 502 a distance that is greater than the distance from the origin to the center of the annulus of the waveguide angle. Similarly, the center of field of view 530 / 570 is translated along axis 501 over a distance greater than the distance from the origin to the center of the intra-waveguide angular annulus.

[0113] As illustrated in Figure 5B, the field of view achieved using the eyepiece waveguide design illustrated in Figure 5A can range from about 50° to about 180° (farthest range) along a first direction by about 50° in a second direction orthogonal to the first direction. Note that the combination of fields of view 510 and 560 in the upper portion of the k-space diagram and fields of view 530 and 570 in the lower portion of the k-space diagram results in a cutout in region 575 that can be masked as needed for a particular application.

[0114] FIG. 6A is a simplified plan view illustrating elements of a multi-projector waveguide display according to an embodiment of the present invention. As shown in FIG. 6A and described more fully below, eyepiece waveguide 600, which may also be referred to as a waveguide display component, includes ICG 620, which may also be referred to as a first ICG. ICG 620 is operable to receive input light from first projector 621. As discussed in connection with FIG. 1, ICG 620 receives input light propagating along a direction having a component aligned with the z-axis, i.e., the normal to the input surface of eyepiece waveguide 600, which lies in the xy plane, and couples at least a portion of the input light into the waveguide.

[0115] Eyepiece waveguide 600 also includes ICG 625, which may be referred to as a second ICG. ICG 625 is operable to receive input light from second projector 626. As discussed in connection with FIG. 1 , ICG 620 receives input light propagating along a direction having a component aligned with the z-axis, i.e., the normal to the input surface of eyepiece waveguide 600, which lies in the xy plane, and couples at least a portion of the input light into the waveguide.

[0116] ICG 620 and ICG 625 are positioned along the x-axis, in the plane of the eyepiece waveguide. Referring to FIG. 6A, waveguide display 600 further includes multiple regions within which light is diffracted into and out of the plane of the waveguide display. These multiple regions include first region 601 and second region 604. In each region, grating lines or other diffractive structures present in one portion of the region are oriented at a predetermined angle relative to other grating lines present in other portions of the region or relative to grating lines in other regions (or others of the multiple regions).

[0117] 6A and 6B, it should be noted that the gratings within some of the regions can perform different diffraction functions depending on the source of the light incident on the gratings. As an example, as light incident on ICG 620 propagates within second portion 606 of second region 604, it can interact with the grating within second portion 606 and be outcoupled from the eyepiece waveguide. That is, the grating within second portion 606 can function as an EPE grating for light from projector 621. In contrast, as light incident on ICG 625 propagates within second portion 606 of second region 604, it can interact with the grating within second portion 606 and be diffracted within the plane of the eyepiece waveguide toward first portion 605. That is, the grating within second portion 606 can function as an OPE grating for light from second projector 626. Similar variations of the effects will be evident for other gratings in other sections, resulting in different functionality (i.e., OPE or EPE functionality) depending on the source of the light propagating within the eyepiece waveguide. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0118] In contrast to the area of ​​the second portion 606 having only a single set of gratings, the overlap region 630 between the first region 601 and the second region 604 will produce multiple effects, e.g., both EPE and OPE effects. Because multiple sets of gratings are present, diffraction effects will be produced for light incident from both projectors.

[0119] The actual implementation used to provide the gratings in first portion 602 and second portion 603 of first region 601 and first portion 605 and second portion 606 of second region 604 can be varied. As an example, the gratings in second portion 603 of first region 601 and first portion 605 of second region 604 (i.e., gratings oriented at −30° with respect to the x-axis) can be formed on a first surface of a substrate used to fabricate the eyepiece waveguide, and the gratings in first portion 602 of first region 601 and second portion 606 of second region 604 (i.e., gratings oriented at 30° with respect to the x-axis) can be formed on a second surface of the substrate opposite the first surface. Thus, overlap region 630 can be formed from gratings present on both surfaces of the eyepiece waveguide.

[0120] FIG. 6B is a simplified plan view illustrating the propagation of light rays within a multi-projector waveguide display according to an embodiment of the present invention.

[0121] 6A and 6B, first region 601 includes a first portion 602, also referred to as an upper portion or top portion, characterized by grid lines 616 oriented at an angle of approximately 30° relative to the x-axis, along which reside ICG 620 and ICG 625. First region 601 also includes a second portion 603, also referred to as a lower portion or bottom portion, characterized by grid lines 618 oriented at an angle of approximately −30° relative to the x-axis. As a result, grid lines 616 and 618 are oriented at an angle of approximately 60° relative to each other. As will be apparent to one skilled in the art, the spacing between grid lines 616 and 618 is not drawn to scale for purposes of clarity.

[0122] Second region 604 includes a first portion 605, also referred to as an upper portion or top portion, characterized by grid lines 629 oriented at an angle of approximately 120° relative to the x-axis. Second region 604 also includes a second portion 606, also referred to as a lower portion or bottom portion, characterized by grid lines 628 oriented at an angle of approximately -120° relative to the x-axis. Consequently, in a manner similar to first region 601, grid lines 629 and 628 in second region 604 are oriented at an angle of approximately 60° relative to one another. As will be apparent to one skilled in the art, the spacing between grid lines 629 and 628 is not drawn to scale for purposes of clarity.

[0123] In overlap region 630, grid line 616 overlaps with grid line 629, and grid line 618 overlaps with grid line 628. Thus, in addition to including a single set of grid lines, overlap region 630 includes multiple sets of overlapping grid lines and may be referred to as a mutual intersection region. This overlap region allows designers to implement designs with larger exit pupils and balance the efficiency of operation of the eyepiece waveguide with increasing exit pupil size, which is more tolerant of pupil movement in the user's eye.

[0124] Although grid lines 616 in first portion 602 of first region 601 and grid lines 618 in second portion 603 of first region 601 are illustrated as intersecting at the x-axis, with no overlap of grid lines 616 in second portion 603 with grid lines 618 in first portion 602, this is not required by embodiments of the present invention. In some embodiments, grid lines 616 extend into second portion 603 and grid lines 618 extend into first portion 602.

[0125] As described more fully herein, the presence of grating lines in different portions of first region 601 and second region 604, including the overlap of grating lines in overlap region 630, allows the grating lines to function as an orthogonal pupil expander (OPE), which diffracts light propagating in the plane of the eyepiece waveguide into new propagation directions and expands the lateral dimensions of light propagating in the eyepiece waveguide, and as an exit pupil expander (EPE), which diffracts light propagating in the plane of the eyepiece waveguide out of the plane of the eyepiece waveguide. Of particular note is that a set of grating lines can function as either an OPE or an EPE, depending on the direction in which light propagates in the eyepiece waveguide. As an example, for a given set of grating lines, light propagating in a first direction can be diffracted within the plane of the eyepiece waveguide (OPE functionality), while light propagating in a second direction orthogonal to the first direction can be diffracted out of the plane of the eyepiece waveguide (EPE functionality).

[0126] 6A and 6B, as light propagates through first portion 602 of first region 601, interaction with grating lines 616 results in diffraction in the plane of the eyepiece waveguide along the direction of the inter-ICG axis. As a result of this diffraction, similar to OPE diffraction, multiple copies of the first copy of the image are formed, propagating in directions aligned with this axis.

[0127] Light propagating from first portion 602 to overlap region 630 undergoes diffraction in and out of the plane of the eyepiece waveguide in multiple directions due to the presence of grating lines oriented approximately 30° relative to the x-axis and grating lines oriented approximately 120° relative to the x-axis. Light propagating in a direction aligned with the x-axis will encounter grating lines 629 and diffract along the direction illustrated by arrow 627 in the plane of the eyepiece waveguide. As light propagates along this direction, it will encounter grating lines 628 and undergo outcoupling events from the eyepiece waveguide. These outcoupling events are illustrated in FIG. 6B by open circles.

[0128] Referring to first portion 605, light propagating in a direction aligned with the x-axis passes through overlap region 630, encounters grating lines 629, and is diffracted along the direction of arrow 627 in the plane of the eyepiece waveguide. During these diffraction events, laddering of light will occur as needed for OPE functionality. As the light further propagates along the direction of arrow 627, it will enter second portion 606, encounter grating lines 628, and undergo additional outcoupling events from the eyepiece waveguide. These outcoupling events, like the outcoupling events produced in overlap region 630, are illustrated in FIG. 6B by open circles.

[0129] Thus, light entering the eyepiece waveguide in ICG 620 and generated by first projector 621 can be outcoupled within second region 604. In the design illustrated in Figures 6A and 6B, light coupled into the eyepiece waveguide in ICG 620 preferably passes through first region 601 without experiencing an outcoupling event, thereby resulting in little or no light loss due to outcoupling; only passage through first region 601 results in diffraction within the plane of the eyepiece waveguide, replicating OPE functionality. As a result, all outcoupling events for light from the first projector are preferably experienced within second region 604, which provides an output that forms one of the sub-displays of the combined display. As shown in FIG. 2B, the cone of rays entering the ICG is centered at a non-normal incidence angle, so that the cone of rays outcoupled within the second region 604 also propagates at a non-normal incidence angle, allowing spatial separation between the sub-displays and tiling of the combined display.

[0130] In addition to light entering ICG 620, light entering ICG 625 will undergo similar interactions as it propagates through second region 604, resulting in OPE interactions, and will undergo EPE interactions within first region 601. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0131] Figure 7A is a simplified plan view illustrating a six-projector waveguide display according to an embodiment of the present invention. In the six-projector design illustrated in Figure 7A, the six projectors are arranged at 60° angles around the periphery of the eyepiece waveguide. The six-projector waveguide display illustrated in Figure 7A is a design that utilizes a reduced grating period.

[0132] Light from six projectors (not shown) is coupled into a shared eyepiece waveguide region via ICGs 710, 713, 714, 716, 718, and 720. The shared eyepiece waveguide region includes three different grating vectors, including grating vector 722, which is aligned with an axis passing through the perpendicular bisector of the line connecting ICGs 713 and 714 and the perpendicular bisector of the line connecting ICGs 718 and 720, i.e., aligned with axis 702, which is oriented vertically; grating vector 724, which is aligned with an axis passing through the perpendicular bisector of the line connecting ICGs 710 and 720 and the perpendicular bisector of the line connecting ICGs 714 and 716, i.e., aligned with an axis oriented at −30° with respect to vertical axis 702; and grating vector 726, which is aligned with an axis passing through the perpendicular bisector of the line connecting ICGs 716 and 718 and the perpendicular bisector of the line connecting ICGs 710 and 713, i.e., aligned with an axis oriented at +30° with respect to vertical axis 702.

[0133] Referring to ICG 710, light incoupled through ICG 710 propagates within regions 712 and 719 along a direction having a component aligned with axis 701. Regions 712 and 719 utilize a design similar to that shown in FIG. 5A , i.e., a chevron design in which the grating in region 712 is tilted at an angle of −120° relative to horizontal axis 701 and the grating in region 719 is tilted at an angle of 120° relative to horizontal axis 701. Light associated with the bottom of the field of view propagates through region 719, undergoes diffraction toward region 712 (e.g., with little or no outcoupling), and is outcoupled from region 712. Similarly, light associated with the top of the field of view propagates through region 712, undergoes diffraction toward region 719 (e.g., with little or no outcoupling), and is outcoupled from region 719. Additional explanations related to these interactions are provided in connection with FIG. 7B .

[0134] By utilizing the six-projector design illustrated in FIG. 7A, which includes six internal coupling gratings and a shared eyepiece waveguide region, a combined conical field of view of approximately 100° is achieved within a polymer eyepiece having a refractive index of approximately 1.75.

[0135] FIG. 7B is a simplified plan view illustrating a single projector element of the six-projector waveguide display illustrated in FIG. 7A. FIG. 7C is a simplified k-space diagram illustrating the operation of the single projector element illustrated in FIG. 7B. With reference to FIGS. 7B and 7C, optical diffraction and the accompanying translation of the field of view in k-space can be explained. As illustrated in FIG. 7B, a portion of the light diffracted from ICG 710 can be represented by ray 740 as the light propagates into region 712. Diffraction from the grating in region 712 will result in the generation of ray 741, which is directed toward the upper half of the waveguide, i.e., region 719. This can be considered an OPE event.

[0136] As it propagates into the upper half of the waveguide, i.e., region 719, diffraction from the grating in region 719 will result in the generation of output ray 742, which propagates downward toward the user, representing light within the upper portion of the user's field of view.

[0137] Similarly, light in the lower portion of the user's field of view will be produced as ray 750, after diffraction from ICG 710, propagates into the upper half of the waveguide, i.e., region 719. Diffraction from the grating into the upper half of the waveguide, i.e., region 719, results in the generation of ray 751 (an OPE event), which propagates into the lower half of the waveguide, i.e., region 712. Diffraction as an EPE event within region 712 will result in the generation of output ray 752, which propagates upward toward the user.

[0138] 7A and 7B include overlap between adjacent grid vectors only in the central region where the grid lines overlap, but in other embodiments, the overlap region can extend closer to each of the individual ICGs. These designs with increased overlap enable the performance that, if the user's pupil moves within the eyebox to a position off-center, the visibility of the field of view is more tolerant of deviations of the user's pupil from a clearly centered pupil location that may result from changes in the user's gaze.

[0139] 7C, diffraction from ICG 710 corresponds to a translation of the field of view 730 to location 732. Diffraction from the grating in region 719 (an OPE event), represented by ray 751, results in a translation of the field of view to location 734, and diffraction in region 712 (an EPE event) results in a translation of the field of view into the eye space region of the k-space diagram.

[0140] Similarly, diffraction from the grating in region 712 (an OPE event), represented by ray 741, results in a translation of the field of view to position 736, and diffraction in region 719 (an EPE event) results in a translation of the k-space diagram of the field of view to the eye space region.

[0141] The k-space diagram in Figure 7C demonstrates that the eyepiece waveguide design illustrated in Figure 7B utilizes a grating with a reduced grating period along axis 701 because the center of field of view 730 is translated along axis 701 over a distance that is less than the distance from the origin to the annulus of the waveguide angle.

[0142] Figure 7D is a simplified k-space diagram illustrating the operation of the six-projector waveguide display shown in Figure 7A. When the analysis performed on a portion of the six-projector waveguide display shown in Figure 7B is extended to five other projectors, a combined field of view containing six partially overlapping fields of view is produced, as shown in Figure 7D. This combined field of view is formed by tiling the individual fields of view, which are approximately cone-shaped fans with circular terminations, resulting in a combined field of view that is circular and characterized by a combined conical field of view of approximately 100° in a polymer eyepiece having a refractive index of approximately 1.75.

[0143] FIG. 8 is a simplified perspective view illustrating the integration of one or more eyepiece waveguides with eyeglasses, according to an embodiment of the present invention. As illustrated in FIG. 8, eyepiece waveguides can be integrated into right and left lens frames 801 and 802 of a pair of eyeglasses. The integration of a first eyepiece waveguide 830 in the right lens frame 801 and a second eyepiece waveguide 840 in the left lens frame 802 enables a wide field of view as a result of the eyepiece waveguide functionality described herein. As illustrated in FIG. 8, a first waveguide display 805 utilizes two eyepiece waveguides 830 and 840, which include ICGs 832 / 842 and CPEs 834 / 844, respectively.

[0144] It should also be understood that the examples and embodiments described herein are for illustrative purposes only, and that various modifications or changes in light thereof will be suggested to those skilled in the art and are to be included within the spirit and scope of the present application and the appended claims.

Claims

1. 1. An eyepiece waveguide for an augmented reality display system, the eyepiece waveguide comprising: a substrate having a first surface and a second surface; a diffractive input coupling element formed on or within the first surface or the second surface of the substrate, the diffractive input coupling element configured to receive an input beam of light and couple the input beam of light into the substrate as a guided beam; a diffractive combination pupil expander-extractor (CPE) element formed on or within the first surface or the second surface of the substrate, the diffractive CPE element including a first portion and a second portion separated by an axis; Equipped with a first set of diffractive optical elements disposed within the first portion and oriented at a positive angle relative to the axis; a second set of diffractive optical elements disposed within the second portion and oriented at a negative angle relative to the axis; Eyepiece waveguide.

2. 2. The eyepiece waveguide of claim 1, wherein the positive angle is approximately 30 degrees and the negative angle is approximately -30 degrees.

3. 10. The eyepiece waveguide of claim 1, wherein the first set of diffractive optical elements comprises a first set of gratings and the second set of diffractive optical elements comprises a second set of diffraction gratings.

4. 2. The eyepiece waveguide of claim 1, wherein the first set of diffractive optical elements extends into the second portion and the second set of diffractive optical elements extends into the first portion, forming an overlap region.

5. The eyepiece waveguide of claim 4 , wherein the overlap region is centered on the axis.

6. The eyepiece waveguide of claim 5 , wherein the axis passes through the diffractive input coupling element.

7. The eyepiece waveguide of claim 1 , wherein the input beam of light impinges on the diffractive input coupling element at a non-zero angle of incidence.

8. 8. The eyepiece waveguide of claim 7, wherein the diffractive input coupling element is characterized by a grating period such that a cone of light rays incoupled by the diffractive input coupling element is centered on an axis parallel to the substrate.

9. 1. An eyepiece waveguide for an augmented reality display system, the eyepiece waveguide comprising: a substrate having a first surface and a second surface; a first diffractive input coupling element formed on or within the first surface or the second surface of the substrate, the first diffractive input coupling element configured to receive a first input beam of light and couple the first input beam of light into the substrate as a first guided beam; a second diffractive input coupling element formed on or within the first surface or the second surface of the substrate, the second diffractive input coupling element configured to receive a second input beam of light and couple the second input beam of light into the substrate as a second guided beam; a diffractive combination pupil expander-extractor (CPE) element formed on or within the first surface or the second surface of the substrate, the diffractive CPE element comprising: receiving the first guided beam from the first diffractive in-coupling element; receiving the second guided beam from the second diffractive in-coupling element; outcoupling at least a portion of the first stimulating beam over a first range of angles to form a first field of view of a combined field of view; outcoupling at least a portion of the second stimulated beam over a second range of angles to form a second field of view of the combined field of view; a diffractive CPE element positioned to perform An eyepiece waveguide comprising:

10. 10. The eyepiece waveguide of claim 9, wherein the diffractive CPE element comprises a first set of gratings positioned within a first portion of a first region oriented at approximately 30° relative to the axis, and a second set of gratings positioned within a second portion of the first region oriented at approximately -30° relative to the axis.

11. 11. The eyepiece waveguide of claim 10, wherein the diffractive CPE element comprises a third set of gratings positioned within a first portion of the second region oriented at approximately 150° relative to the axis, and a fourth set of gratings positioned within a second portion of the second region oriented at approximately -150° relative to the axis.

12. 10. The eyepiece waveguide of claim 9, wherein the first input beam of light is incident on the substrate at a non-normal angle of incidence and a first field of view of the combined field of view is centered at the non-normal angle of incidence.

13. 13. The eyepiece waveguide of claim 12, wherein the second input beam of light is incident on the substrate at zero minus the non-normal incidence angle, and a second field of view of the combined field of view is centered at zero minus the non-normal incidence angle.

14. 10. The eyepiece waveguide of claim 9, wherein the first field of view and the second field of view are tiled.

15. 15. The eyepiece waveguide of claim 14, wherein a portion of the first field of view overlaps a portion of the second field of view.

16. 1. A waveguide display disposed within a pair of eyeglasses, the waveguide display comprising: a first projector; a second projector; and a first internal coupling grating (ICG) optically coupled to the first projector; a second ICG optically coupled to the second projector, the second ICG having an axis passing through the first ICG and the second ICG; a first diffractive region optically coupled to the first ICG, a first portion comprising a first set of gratings oriented at a positive angle relative to the axis; a second portion comprising a second set of gratings oriented at a negative angle relative to the axis; a first diffraction region including: a second diffractive region optically coupled to the second ICG, a first portion comprising a third set of gratings oriented at 180°—the positive angle relative to the axis; a second portion comprising a fourth set of gratings oriented at −180° relative to the axis—the negative angle; a second diffractive region including A waveguide display comprising:

17. 17. The waveguide display of claim 16, wherein the first diffractive region and the second diffractive region overlap to form an overlap region.

18. The waveguide display of claim 17 , wherein the overlap region is located at a midpoint between the first ICG and the second ICG.

19. 17. The waveguide display of claim 16, wherein first display light from the first projector impinges on the first ICG at a non-zero angle of incidence.

20. 20. The waveguide display of claim 19, wherein the first ICG is characterized by a grating period such that a cone of light rays internally coupled by the first ICG is centered on an axis passing through the first ICG and the second ICG.

21. 21. The waveguide display of claim 20, wherein the second ICG is characterized by the grating period.

22. 17. The waveguide display of claim 16, wherein the first set of gratings and the second set of gratings are blazed and characterized by a reduced outcoupling efficiency for light from the first projector.

23. 17. The waveguide display of claim 16, wherein the third set of gratings and the fourth set of gratings are blazed and characterized by a reduced outcoupling efficiency for light from the second projector.

24. 1. A method of operating an eyepiece waveguide defined by a first region and a second region, the method comprising: Directing light from a first projector to impinge on a first internal coupling grating (ICG); diffracting a percentage of light from the first projector into a first portion of a first region of the eyepiece waveguide, into a first portion of the second region, into a second portion of the second region, and out of the eyepiece waveguide; diffracting another proportion of the light from the first projector into a second portion of the first region of the eyepiece waveguide, into a second portion of the second region, into a first portion of the second region, and out of the eyepiece waveguide; directing light from a second projector to impinge on a second ICG; diffracting a percentage of light from the second projector into a first portion of a second region of the eyepiece waveguide, into a first portion of the first region, into a second portion of the first region, and out of the eyepiece waveguide; diffracting another proportion of the light from the second projector into a second portion of a second region of the eyepiece waveguide, into a second portion of the first region, into a first portion of the first region, and out of the eyepiece waveguide; A method comprising:

25. The first region includes: a first set of diffractive optical elements disposed within a first portion of the first region and oriented at a positive angle relative to the axis; a second set of diffractive optical elements disposed within a second portion of the first region and oriented at a negative angle relative to the axis; and Including, The second region is a third set of diffractive optical elements disposed within a first portion of the second region and oriented at 180° plus the negative angle relative to the axis; a fourth set of diffractive optical elements disposed within a second portion of the second region and oriented at 180°—the positive angle relative to the axis; and 25. The method of claim 24, comprising:

26. 26. The method of claim 25, wherein the first set of diffractive optical elements comprises a first set of gratings and the second set of diffractive optical elements comprises a second set of gratings, and the first set of gratings and the second set of gratings are blazed and characterized by a reduced outcoupling efficiency for light from the first projector.

27. 26. The method of claim 25, wherein the third set of diffractive optical elements comprises a third set of gratings and the fourth set of diffractive optical elements comprises a fourth set of gratings, and the third set of gratings and the fourth set of gratings are blazed and characterized by a reduced outcoupling efficiency for light from the second projector.

28. 26. The method of claim 25, wherein the positive angle is about 30 degrees and the negative angle is about -30 degrees.

29. The method of claim 24 , wherein the first region and the second region form an overlapping region.

30. 30. The method of claim 29, wherein the overlap region is located at a midpoint between the first ICG and the second ICG.

31. light from the first projector impinges on the first ICG at a first non-zero angle of incidence; the light from the second projector impinges on the second ICG at a second non-zero angle of incidence equal to zero minus the first non-zero angle of incidence; 25. The method of claim 24.

32. a first field of view of a first portion of the second region is centered at the first non-zero angle of incidence; a second field of view of the first portion of the first region is centered at the second non-zero angle of incidence; 32. The method of claim 31 .

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