Method and system for eyepiece waveguide display with multi-directional transmit architecture

Abstract

An eyepiece waveguide for augmented reality applications includes a substrate and a set of in-coupling diffractive optical elements coupled to the substrate. A first subset of the set of in-coupling diffractive optical elements is operable to diffract light into the substrate along a first range of propagation angles and a second subset of the set of in-coupling diffractive optical elements is operable to diffract light into the substrate along a second range of propagation angles. The eyepiece waveguide also includes a combined pupil expander diffractive optical element coupled to the substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 359,561, filed on July 8, 2022, entitled “Multi-Directional Transmission and Multi-Combiner EP Architecture,” the disclosure of which is incorporated herein by reference in its entirety for all purposes. Background Art

[0003] Modern computing and display technologies have facilitated the development of so-called "virtual reality" (VR) or "augmented reality" (AR) experience systems, in which digitally reproduced images or portions thereof are presented to a viewer in a manner that appears real or can be perceived as real. The scenarios typically involve the presentation of digital or virtual image information that is opaque to other actual real-world visual input; AR scenarios typically involve the presentation of digital or virtual image information as an augmentation of the visualization of the actual world around the viewer.

[0004] Despite advances in these display technologies, there remains a need in the art for improved methods and systems related to augmented reality systems, and particularly display systems. Summary of the invention

[0005] Embodiments of the present invention generally relate to AR / MR products using a single active layer diffractive waveguide. For example, some embodiments use multi-directional emission, diffusion, and outcoupling based on a single layer diffractive optical waveguide to maximize the augmented reality display field of view in the eyepiece.

[0006] The field of view of an AR display using a diffractive optical waveguide is largely determined by the refractive index of the waveguide material and the underlying grating architecture used for coupling, diffusing, and outcoupling of light. The embodiments described herein utilize a unique architecture based on multi-directional emission of light into the waveguide, where diffusion and outcoupling diffractive elements arranged in series enable a larger field of view than is essentially possible with a unidirectional coupling and emission architecture.

[0007] According to an embodiment of the present invention, an AR head-mounted device is provided. The AR head-mounted device includes a projector and an eyepiece waveguide supporting multi-directional emission. The eyepiece waveguide has a world side and a user side, and includes a first group of one or more coupling-in diffractive optical elements, which are coupled to the world side of the eyepiece waveguide. A first subset of the first group of one or more coupling-in diffractive optical elements is operable to diffract a first light into the eyepiece waveguide, wherein the diffracted first light is characterized by a first angle range. A second subset of the first group of one or more coupling-in diffractive optical elements is operable to diffract a second light into the eyepiece waveguide, wherein the diffracted second light is characterized by a second angle range different from the first angle range. The eyepiece waveguide also includes a second group of one or more coupling-in diffractive optical elements, which are coupled to the user side of the eyepiece waveguide. A third subset of the second group of one or more coupling-in diffractive optical elements is operable to diffract light within the first angle range. The AR head-mounted device also includes a combined pupil expander.

[0008] A fourth subset of the second group of one or more coupled-in diffractive optical elements is operable to diffract light within the second angular range. The AR head mounted device can utilize a single waveguide. The eyepiece waveguide can support the propagation of multiple wavelengths of light. The combined pupil expander can be operable to diffuse light laterally in the eyepiece waveguide and couple light out through the user side of the eyepiece waveguide. At least one of the first group of one or more coupled-in diffractive optical elements or the second group of one or more coupled-in diffractive optical elements can overlap.

[0009] According to another embodiment of the present invention, an eyepiece waveguide for augmented reality applications is provided. The eyepiece waveguide includes a substrate and a set of in-coupling diffractive optical elements coupled to the substrate. A first subset of the set of in-coupling diffractive optical elements is operable to diffract light into the substrate along a first propagation angle range; and a second subset of the set of in-coupling diffractive optical elements is operable to diffract light into the substrate along a second propagation angle range. The eyepiece waveguide also includes a combined pupil expander diffractive optical element coupled to the substrate.

[0010] The first subset of the set of in-coupling diffractive optical elements may be characterized by a first grating periodicity, and the second subset of the set of in-coupling diffractive optical elements may be characterized by a second grating periodicity greater than the first grating periodicity. The combined pupil expander diffractive optical element may include a first region characterized by a first grating orientation and a second region characterized by a second grating orientation different from the first grating orientation. The eyepiece waveguide may also include a second set of in-coupling diffractive optical elements coupled to the substrate, wherein the first subset of the second set of in-coupling diffractive optical elements is operable to diffract light into the substrate along the first propagation angle range. The set of in-coupling diffractive optical elements may be coupled to the substrate on a world-side surface; and the second set of in-coupling diffractive optical elements may be coupled to the substrate on a user-side surface opposite to the world-side surface. The eyepiece waveguide may also include a second combined pupil expander diffractive optical element coupled to the substrate. The combined pupil expander diffractive optical element is coupled to the substrate on a world-side surface; and the second combined pupil expander diffractive optical element is coupled to the substrate on a user-side surface opposite to the world-side surface. The eyepiece waveguide is optically coupled to a projector, which is operable to output a red wavelength, a green wavelength, and a blue wavelength, wherein the eyepiece waveguide is operable to support light propagation of the red wavelength, the green wavelength, and the blue wavelength.

[0011] According to a specific embodiment of the present invention, an eyepiece waveguide for augmented reality applications is provided. The eyepiece waveguide includes a substrate and a set of in-coupling diffractive optical elements coupled to the substrate. The set of in-coupling diffractive optical elements includes a first in-coupling diffractive optical element and a second in-coupling diffractive optical element, which are operable to diffract light into the substrate along a first propagation angle range; and a third in-coupling diffractive optical element, which is operable to diffract light into the substrate along a second propagation angle range. The eyepiece waveguide also includes a combined pupil expander diffractive optical element coupled to the substrate. The combined pupil expander includes a first portion, which faces a world-side surface and includes a first region characterized by a first grating vector and a second region characterized by a second grating vector; and a second portion, which faces a user-side surface and includes a third region characterized by the first grating vector and a fourth region characterized by a third grating vector.

[0012] The first in-coupling diffractive optical element and the second in-coupling diffractive optical element are characterized by a first grating periodicity, and the third in-coupling diffractive optical element is characterized by a second grating periodicity that is less than the first grating periodicity. The first region is characterized by a first grating orientation, and the second region is characterized by the first grating orientation. The third region is characterized by a first grating orientation, and the second region is characterized by a second grating orientation that is different from the first grating orientation. The set of in-coupling diffractive optical elements may also include a fourth in-coupling diffractive optical element and a fifth in-coupling diffractive optical element operable to diffract light into the substrate along the first propagation angle range; and a sixth in-coupling diffractive optical element operable to diffract light into the substrate along the second propagation angle range. The first in-coupling diffractive optical element, the second in-coupling diffractive optical element, and the third in-coupling diffractive optical element may be coupled to the substrate on a world-side surface; and the fourth in-coupling diffractive optical element, the fifth in-coupling diffractive optical element, and the sixth in-coupling diffractive optical element may be coupled to the substrate on a user-side surface opposite to the world-side surface. The fourth in-coupling diffractive optical element and the fifth in-coupling diffractive optical element may be characterized by a first grating periodicity, and the sixth in-coupling diffractive optical element may be characterized by a second grating periodicity that is smaller than the first grating periodicity. The eyepiece waveguide may be optically coupled to a projector that is operable to output a red wavelength, a green wavelength, and a blue wavelength, wherein the eyepiece waveguide is operable to support light propagation of the red wavelength, the green wavelength, and the blue wavelength. The first region may be located on the world side, opposite to the third region located on the user side. The second region may be located on the world side, opposite to the fourth region located on the user side. The first in-coupling diffractive optical element and the second in-coupling diffractive optical element may be characterized by a grating vector k L Characterization; The third coupling diffractive optical element can be composed of a grating vector k H The first region and the third region may be characterized by a grating vector k1; the second region may be characterized by a grating vector k3; and the fourth region may be characterized by a grating vector k2. The diffraction paths of the red wavelength and the green wavelength are k L →k2→k3, and the diffraction path of the blue wavelength is k H →k1→k2.

[0013] These and other embodiments of the present disclosure, as well as many of its advantages and features, are described in more detail in conjunction with the following text and corresponding drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1A is a simplified cross-sectional view showing elements of an eyepiece waveguide according to an embodiment of the present invention.

[0015] Figure 1B is a simplified k-space diagram showing the field of view and grating vectors of the eyepiece waveguide according to an embodiment of the present invention.

[0016] Figure 1C is a simplified plan view of the world side of a combined pupil expander (CPE) of an eyepiece waveguide according to an embodiment of the present invention.

[0017] Figure 1D yes Figure 1C A simplified plan view of the user side of the CPE is shown.

[0018] Figure 2A is a simplified k-space diagram showing the field of view and grating vectors of an eyepiece waveguide operating at multiple wavelengths in accordance with an embodiment of the present invention.

[0019] Figure 2B Shows Figure 2A An enlarged portion of the k-space map is shown.

[0020] Figure 2C is a graph showing the number of bounces experienced by light traveling 2 mm as a function of angle.

[0021] Figure 3A is a simplified k-space diagram showing the field of view and ICG grating vectors of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0022] Figure 3B is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0023] Figure 3C yes Figure 3B A simplified plan view of the user side of the eyepiece waveguide with multi-directional emission is shown.

[0024] Figure 3D is a simplified plan view of a single-sided eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0025] Figure 4A is a simplified k-space diagram showing the field of view and CPE grating vectors of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0026] Figure 4B is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0027] Figure 4C yes Figure 4B A simplified plan view of the user side of the eyepiece waveguide with multi-directional emission is shown.

[0028] Figure 4Dis a simplified plan view of the world side of an eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention.

[0029] Figure 4E yes Figure 4D A simplified plan view of the user side of an eyepiece waveguide including a two-dimensional grating with multi-directional emission is shown.

[0030] Figure 4F is a diagram showing an embodiment of the present invention Figure 4D and 4E Simplified k-space diagram of the field of view and CPE grating vectors for the eyepiece waveguide with multi-directional emission shown.

[0031] Figure 4G FIG. 1 is a diagram showing another embodiment of the present invention. Figure 4D and 4E Simplified k-space diagram of the field of view and CPE grating vectors for the eyepiece waveguide with multi-directional emission shown.

[0032] Figures 5A-5C Normalized efficiency distributions for red, green, and blue wavelengths for a unidirectional emission design according to an embodiment of the present invention are shown, respectively.

[0033] Figures 5D-5F Normalized efficiency distributions for red, green, and blue wavelengths for a multi-directional emission design according to an embodiment of the present invention are shown, respectively.

[0034] Fig. 6A is a simplified k-space diagram showing the field of view and ICG grating vectors of the first eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0035] Figure 6B is a simplified k-space diagram showing the field of view and CPE grating vectors of the first eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0036] Figure 6C is a simplified plan view of the world side of a first eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0037] Fig.6D yes Figure 6C A simplified plan view of the user side of the first eyepiece waveguide with multi-directional emission is shown.

[0038] Fig. 7A is a simplified k-space diagram showing the field of view and ICG grating vectors of a second eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0039] Figure 7Bis a simplified k-space diagram showing the field of view and CPE grating vectors of a second eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0040] Figure 7C is a simplified plan view of the world side of a second eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0041] Fig.7D yes Figure 7C A simplified plan view of the user side of a second eyepiece waveguide with multi-directional emission is shown.

[0042] Fig. 8A is a simplified k-space diagram showing the field of view and ICG grating vectors of a third eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0043] Figure 8B is a simplified k-space diagram showing the field of view and CPE grating vectors of a third eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0044] Figure 8C is a simplified plan view of the world side of a third eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0045] Fig.8D yes Figure 8C A simplified plan view of the user side of the third eyepiece waveguide with multi-directional emission is shown.

[0046] Fig.9A is a simplified k-space diagram showing the field of view and ICG grating vectors of a fourth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0047] Fig. 9B is a simplified k-space diagram showing the field of view and CPE grating vectors of a fourth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0048] Fig. 9C is a simplified plan view of the world side of a fourth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0049] Fig.9D yes Fig. 9C Simplified plan view of the user side of the fourth eyepiece waveguide with multi-directional emission shown.

[0050] Fig. 10A is a simplified k-space diagram showing the field of view and ICG grating vectors of a fifth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0051] Fig. 10Bis a simplified k-space diagram showing the field of view and CPE grating vectors of the fifth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0052] Fig. 10C is a simplified plan view of the world side of a fifth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0053] Fig. 10D yes Fig. 10C A simplified plan view of the user side of the fifth eyepiece waveguide with multi-directional emission is shown.

[0054] Fig.11A is a simplified k-space diagram showing the field of view and ICG grating vectors of the sixth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0055] Fig. 11B is a simplified k-space diagram showing the field of view and CPE grating vectors of the sixth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0056] Fig. 11C is a simplified plan view of the world side of a sixth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0057] Fig.11D yes Fig. 11C A simplified plan view of the user side of the sixth eyepiece waveguide with multi-directional emission is shown.

[0058] Fig. 12A is a simplified k-space diagram showing the field of view and ICG grating vectors of the seventh eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0059] Fig. 12B is a simplified k-space diagram showing the field of view and CPE grating vectors of the seventh eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0060] Fig. 12C is a simplified plan view of the world side of a seventh eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0061] Fig.12D yes Fig. 12C A simplified plan view of the user side of the seventh eyepiece waveguide with multi-directional emission is shown.

[0062] Fig.13A is a simplified k-space diagram showing the field of view and ICG grating vectors of the eighth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0063] Fig. 13Bis a simplified k-space diagram showing the field of view and CPE grating vectors of the eighth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0064] Fig. 13C is a simplified plan view of the world side of an eighth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0065] Fig.13D yes Fig. 13C A simplified plan view of the user side of the eighth eyepiece waveguide with multi-directional emission is shown.

[0066] Fig.14A is a simplified k-space diagram showing the field of view and ICG grating vectors of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention.

[0067] Fig. 14B is a simplified k-space diagram showing the field of view and CPE grating vectors of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention.

[0068] Fig. 14C is a simplified plan view of the world side of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention.

[0069] Fig.14D yes Fig. 14C A simplified plan view of the user side of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission is shown.

[0070] Fig.15A is a simplified k-space diagram showing the field of view and ICG grating vectors of a second eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention.

[0071] Fig. 15B is a simplified k-space diagram showing the field of view and CPE grating vectors of a second eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention.

[0072] Fig. 15C is a simplified plan view of the world side of a second eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention.

[0073] Fig.15D yes Fig. 15C A simplified plan view of the user side of a second eyepiece waveguide including a two-dimensional grating with multi-directional emission is shown.

[0074] Fig.16A is a simplified k-space diagram showing the field of view and ICG grating vectors of a wide field of view eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0075] Fig. 16B is a simplified k-space diagram showing the field of view and CPE grating vectors of a wide field of view eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0076] Fig. 16C is a simplified plan view of the world side of a wide field of view eyepiece waveguide with multi-directional emission in accordance with an embodiment of the present invention.

[0077] Fig.16D yes Fig. 16C A simplified plan view of the user side of a wide field of view eyepiece waveguide with multi-directional emission is shown.

[0078] Fig.17A is a simplified cross-sectional diagram showing an eyepiece waveguide with a double-sided ICG according to an embodiment of the present invention.

[0079] Fig. 17B It is shown Fig.14A Exploded plan view of the bilateral ICG shown.

[0080] Fig. 17C is a simplified cross-sectional view showing a metallized blazed grating according to an embodiment of the present invention.

[0081] Fig.17D is a simplified cross-sectional view showing a coated blazed grating according to an embodiment of the present invention.

[0082] Fig.17E is a simplified cross-sectional view showing a coated tilted grating according to an embodiment of the present invention.

[0083] Fig.17F is a simplified cross-sectional view showing a coated blazed grating according to an embodiment of the present invention.

[0084] Fig.18A is a perspective view of a two-dimensional ICG according to an embodiment of the present invention.

[0085] Fig.18B is a perspective view of a two-dimensional ICG according to another embodiment of the present invention.

[0086] Fig.18C is a perspective view of a two-dimensional ICG according to a third embodiment of the present invention.

[0087] Fig.18D is a perspective view of a two-dimensional ICG according to a fourth embodiment of the present invention.

[0088] Fig.19A is a simplified k-space diagram showing the field of view and ICG grating vectors of an eyepiece waveguide with multi-directional emission and two ICGs according to an embodiment of the present invention.

[0089] Fig.19Bis a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission and two ICGs according to an embodiment of the present invention.

[0090] Fig.19C yes Fig.19B Simplified plan view of the user side of the eyepiece waveguide with multi-directional emission and two ICGs shown.

[0091] Fig. 20A is a simplified k-space diagram showing the field of view and ICG grating vectors of the eyepiece waveguide according to an embodiment of the present invention.

[0092] Fig. 20B is a simplified k-space diagram showing the field of view and ICG grating vectors of another eyepiece waveguide according to an embodiment of the present invention.

[0093] Fig. 20C is a simplified k-space diagram showing the field of view and ICG grating vectors of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention.

[0094] Fig.21A is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention, wherein blue light is emitted in a first direction.

[0095] Fig. 21B yes Fig.21A A simplified plan view of the user side of an eyepiece waveguide with multi-directional emission is shown, where blue light is emitted in a first direction.

[0096] Fig. 21C is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention, wherein blue light is emitted in the second direction.

[0097] Fig.21D yes Fig. 21C A simplified plan view of the user side of the eyepiece waveguide with multi-directional emission is shown, where blue light is emitted in a second direction.

[0098] Fig.22A is a simplified k-space diagram showing the field of view, ICG grating vector, OPE grating vector and CPE grating vector of an eyepiece waveguide with multi-directional emission according to another embodiment of the present invention.

[0099] Fig. 22B is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to another embodiment of the present invention.

[0100] Fig.23 Image overlap in k-space and corresponding eyepiece designs are shown according to various embodiments of the present invention.

[0101] Fig.24A perspective view showing a wearable device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0102] There has been relatively little research on multi-directional emission in the context of diffractive waveguide combiners, focusing primarily on architectures where light is emitted from a projector in two opposite and parallel directions. Due to their simplicity and waveguide efficiency, most optical waveguides available on the market typically rely on unidirectional emission of light. In contrast to this prior art, the architecture described herein (many examples are below) emits light from a projector into different non-parallel directions. The embodiments described herein are useful in the context of augmented reality (AR) systems including AR headsets. Additional description related to AR headsets is provided in U.S. Patent Application Publication No. 2019 / 0179149, the disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0103] In the embodiments described herein, the proposed multi-directional emission waveguide design uniquely solves some of the fundamental constraints of diffractive optical AR displays. For example, the field of view achieved using a single waveguide layer for red, green, and blue wavelengths is partially limited and determined by the material refractive index. In addition, due to the frequency / wavelength dependence of light propagation within the waveguide, the uniformity of the display is severely affected. The multi-directional emission and multi-combiner designs discussed herein enable the field of view to be greater than the fundamental limit and achieve a better uniformity profile. In other words, the complexity of multi-directional emission is suitable for overcoming specific fundamental limitations of waveguide designs based on unidirectional emission.

[0104] Figures 1A-1D The basic functionality of an eyepiece waveguide based on unidirectional transmission is shown, in which an input coupling grating (ICG) couples light from a projector into a high refractive index medium (e.g., glass) of the eyepiece waveguide.

[0105] Figure 1A is a simplified cross-sectional view showing elements of an eyepiece waveguide according to an embodiment of the present invention. Figure 1A As shown, the eyepiece waveguide 100 includes an input coupling grating (ICG) 110 formed on a first portion of the eyepiece waveguide and a combined pupil expander (CPE), the combined pupil expander (CPE) including a grating structure 120 formed on a second portion of the world side of the eyepiece waveguide and a grating structure 122 formed on a second portion of the user side of the eyepiece waveguide. Light is coupled into the eyepiece waveguide 100 using the ICG 110 and coupled out toward the user using the CPE including the grating structure 120 and the grating structure 122.

[0106] In the illustrated embodiment, the grating depth in the CPE varies with lateral position and increases with increasing distance from the ICG 110, thereby increasing the grating coupling efficiency with varying lateral position. In other embodiments, the grating depth or other grating parameters related to the grating strength are constant with varying lateral position. Therefore, both varying grating parameters and constant grating parameters are included within the scope of the present invention. In addition, although the figures herein do not show varying grating parameters, such as varying grating depth, it is understood that in the embodiments described herein, the grating parameters can vary.

[0107] Figure 1B is a simplified k-space diagram showing the field of view and grating vectors of an eyepiece waveguide according to an embodiment of the present invention. Figure 1B , k-space diagrams can be used to understand the flow of light using this momentum space representation. Figure 1B As shown, the inner circle with radius = 1 represents the momentum of light at all physically possible angles of incidence in free space or vacuum. The outer circle with radius = glass refractive index (in this case, n = 2) represents all physically possible angles of incidence within the eyepiece waveguide medium (e.g., glass). The field of view (FOV) corresponding to the projector is given by Figure 1B 1 and 2. The FOV of the projector (e.g., 53° x 53°) is described by the range of the barrel-shaped box shown. Therefore, light coupled or emitted into the glass has momentum located in the annular region in momentum space (i.e., between the r=n=1 inner circle and the r=n=2 outer circle), and, due to total internal reflection, such light will not escape from the eyepiece waveguide unless it interacts with the diffraction grating, which changes the momentum. For light coupled into the waveguide via the ICG 110, the FOV corresponding to the projector (e.g., a FOV of 53° x 53°) will be offset in k-space, as indicated by the vector k ICG Indicated.

[0108] Figure 1B The grating vectors in the k-space representation shown indicate not only the direction but also the pitch or grating periodicity for a given design wavelength. For example, for an eyepiece waveguide designed specifically for the green wavelength of 525 nm, Figure 1B The k-space representation shown has k ICG =1.5, which corresponds to a one-dimensional grating with pitch = 525nm / 1.5 = 350nm.

[0109] For a CPE with 1D binary square ridge gratings, the diffraction vectors k1 and k2 are defined by the momentum translation of k1 and k2. The diffraction of the light propagating in the eyepiece waveguide by these diffraction gratings allows spreading the emitted light over a larger area, e.g. for exit pupil expansion. At the same time, these gratings also couple out the spread light, which corresponds to Figure 1BThe momentum translation shown by the dashed vector in the figure. This outcoupled light is visible to the user's eye and the digital content can then be observed. Because the eyepiece waveguide can have two side patterns (i.e., facing both the user and the outside world), the implementation can use 2D gratings on one side of the eyepiece waveguide, where these 2D gratings are defined by the momentum translations k1 and k2; or 1D gratings can be used, where each grating is formed on one of the two sides of the eyepiece waveguide.

[0110] It should be noted that reference Figure 1B As shown in the k-space diagram, light corresponding to the FOV that does not overlap with the annular region between r=n=1 and r=n=2 will not propagate via TIR. Therefore, the user can only access the portion of the FOV that overlaps with the annular region.

[0111] Figure 1C is a simplified plan view of the world side of an eyepiece waveguide according to an embodiment of the present invention. Figure 1C , the light coupled into ICG 110 is vector k ICG 1 and 2. As shown propagating toward a CPE including grating structure 120 and grating structure 122. In this embodiment, the grating depth may increase from a first value at the upper right corner of the eyepiece waveguide to a larger value at the lower left corner of the eyepiece waveguide. The grating variation may be continuous, stepped, etc. The world side of the CPE includes a grating defined by grating vector k1, which will diffract toward the upper left portion of the CPE.

[0112] Figure 1D yes Figure 1C A simplified plan view of the user side of the eyepiece waveguide is shown. Figure 1C As discussed, the grating depth in region 130 may increase from a first value on the right side of the eyepiece waveguide to a larger value on the left side of the eyepiece waveguide. The user side of the CPE includes a grating vector k2 in region 130 and k in region 140. rec The grating vector k2 diffracts the light toward the lower side of the CPE, k rec The light is diffracted back to region 130 to provide a light recycling function. Figure 1B The grating vector k associated with this "recycling" grating is shown rec .

[0113] Also refer to Figure 1C and 1D , light propagating in the eyepiece waveguide may be diffracted as indicated by the grating vectors k1 and k2 so as to be Figure 1B In addition, the light can also be diffracted as shown by the grating vectors k1 and k2 so that Figure 1BThe dashed vectors k1 and k2 in FIG. 1 are shown coupled out toward the user. The periods of the CPE gratings coupled to the world side and the user side can be equal, but with different orientations, although this is not required. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0114] Due to grating pitch mismatch, an eyepiece waveguide designed to provide good image quality for AR displays at green wavelengths will typically not provide similar image quality for AR displays at red and blue wavelengths.

[0115] Figure 2A is a simplified k-space diagram showing the field of view and grating vectors of an eyepiece waveguide operating at multiple wavelengths according to an embodiment of the present invention. In this k-space representation, the eyepiece waveguide adopts a unidirectional transmission architecture and is designed for green wavelength operation, with a field of view of 300°x300° for all three wavelengths, namely, red (628nm), green (525nm), and blue (455nm).

[0116] Figure 2B Shows Figure 2A The enlarged portion of the k-space image is shown. Figure 2B As shown, a large portion of the red FOV lies outside the outer circle of r = n = 2, resulting in light in this non-overlapping region not propagating in the waveguide and, therefore, not appearing at the corresponding incident angle. For an eyepiece waveguide made of glass with a refractive index of n = 2, the maximum square FOV that can be achieved is approximately 24° x 24°.

[0117] Besides this fundamental limitation, another problem is that the three different wavelengths interact very differently with the grating inside a glass waveguide, not only because of the grating vector mismatch and the wavelength dependence of diffraction, but also because the propagating light hits the grating differently. In other words, the number of bounces between the two sides of the waveguide varies with wavelength. In general, TIR light with momentum values ​​close to the outer circle of r = n = 2 (e.g., Figure 2A Compared to the red FOV in the image above, the momentum value of TIR light close to the inner circle of r=n=1 (e.g. Figure 2A The blue FOV in the image above bounces more frequently.

[0118] Figure 2C is a graph showing the number of bounces experienced by light traveling 2 mm as a function of angle. For light with a FOV of 550° x 550°, emitted within an eyepiece waveguide of 0.35 mm thickness and n=2.0, Figure 2C The number of bounces experienced within a propagation distance of 2 mm represented by angle is shown. Figure 2CThe upper right corner of represents momentum close to the outer circle of r=n=2 in k-space, and the lower left corner represents momentum close to the inner circle of r=n=1 in k-space. For these opposite cases, the large difference in bounce frequency leads to interactions with the diffraction grating and large differences between red and blue light propagation that are unique to single-layer designs. As a result, these limitations often lead to non-uniformity issues in the display. Therefore, embodiments of the present invention utilize a novel architecture that can avoid these potential differences and provide improved performance.

[0119] Figure 3A is a simplified k-space diagram showing the field of view and ICG grating vectors of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 3B is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 3C yes Figure 3B A simplified plan view of the user side of the eyepiece waveguide with multi-directional emission is shown. In addition to the ICG and CPE regions of the eyepiece waveguide, Figure 3B and 3C The fan angle of light launched into the eyepiece waveguide using ICG is also shown.

[0120] Although about Figures 3A-3C An exemplary eyepiece waveguide with multi-directional emission is shown, but it should be understood that a variety of multi-directional emission architectures are included within the scope of the present invention.For this illustration, a 300° x 300° FOV is used.

[0121] refer to Figure 3B and 3C , the exemplary embodiment adopts a multi-directional emission eyepiece waveguide design, wherein a separate ICG pupil (such as Figure 3B 310, green ICG 312 and blue ICG 314) and Figure 3C 320 is shown disposed on the user side of the eyepiece waveguide. Thus, these four ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors of the various ICGs designed for green wavelengths are different for blue light (and the blue ICG) than for red and green light (and the red and green ICGs). Although Figure 3C The illustrated embodiment includes a blue ICG 320 disposed on the user side of the eyepiece waveguide, but this is not required and in some embodiments, the blue ICG 32 is optional.

[0122] like Figure 3A As shown, corresponding to the grating vector k red and raster vector k greenThe gratings of are characterized by the same grating size (ie, the same grating periodicity, e.g., 525 nm / ~1.5≈350 nm), and correspond to the grating vector k blue The gratings of are characterized by a larger grating size (i.e., a smaller grating periodicity, e.g., 525 nm / ~1.9≈276 nm). Thus, for the red ICG 310 and the green ICG 312, light at the center of the FOV is diffracted into the eyepiece waveguide to produce a red FOV 311 for red wavelengths and a green FOV 313 for green wavelengths. Both FOVs are within the annular region defined by r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using a blue ICG 314 coupled to the world side of the eyepiece waveguide or a blue ICG 320 coupled to the user side of the eyepiece waveguide is as shown by k blue Thus, for blue ICG 314 and blue ICG 320, light at the center of the FOV is diffracted into the eyepiece waveguide to produce a blue FOV 331. This FOV is within the annular region defined by r=n=1 and r=n=2.

[0123] refer to Figure 3B , the orientation of the gratings in the red ICG 310 and the green ICG 312 is oriented so that the red light and the green light are emitted into the eyepiece waveguide toward the region 344 of the CPE 340 and are directed to the lower left portion of the CPE. The orientation of the gratings in the blue ICG 314 and the blue ICG 320 is oriented so that the blue light is emitted into the eyepiece waveguide toward the region 342 of the CPE 340 on the world side and the region 352 of the CPE 350 on the user side and is directed to the upper left portion of the CPE.

[0124] Referring to the diffraction from the blue ICG, since the eyepiece waveguide is designed for the green wavelength, the green light at the center of the FOV diffracted by the blue ICG is diffracted into the green FOV 330, which partially overlaps the area outside the r=n=2 circle. However, the light of the blue wavelength will be diffracted into the blue FOV 331 within the annular region. Therefore, this wavelength-specific multi-directional emission architecture is able to achieve a full 30° x 30° FOV because the barrel-shaped frames corresponding to the red FOV 311, green FOV 313, and blue FOV 331 corresponding to the TIR light are completely located within the annular region.

[0125] The grating vectors in the CPE, including grating vector k2 in region 344 of CPE 340 and grating vector k3 in region 354 of CPE 350, are designed so that light diffuses within the waveguide and emerges from the central region of the eyepiece.

[0126] although Figure 3CBlue light is shown being coupled in by a blue ICG 320 coupled to the user side of CPE 310 and diffracted into CPE 350, but this is not required and in some embodiments, the blue ICG 32 is optional.

[0127] It should be noted that although Figure 3B and 3C In the embodiments, particular diffractive structures are shown as being fabricated on both the world side and the user side, but this is merely exemplary. In other embodiments, diffractive structures shown as coupled to the world side may be fabricated so that they are coupled to the user side, and diffractive structures shown as coupled to the user side may be fabricated so that they are coupled to the world side. Thus, diffractive structures may be implemented on either side as appropriate for a particular application. Furthermore, as described more fully below, diffractive structures may be fabricated so that they are coupled to a single side of the eyepiece waveguide.

[0128] Figure 3D is a simplified plan view of a single-sided eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 3D The single-sided eyepiece waveguide shown with Figure 3B and 3C The eyepiece waveguides shown share common components. Figure 3D In the illustrated embodiment, region 346 includes gratings corresponding to both grating vector k2 and grating vector k3. Figure 3D In the embodiment shown, a single-sided design is used to achieve Figure 3B and 3C Functionality discussed.

[0129] It should be noted that the eyepiece waveguide can be fabricated using a substrate with a specific refractive index, with a diffractive structure of a single refractive index or with different regions characterized by different refractive indices. This can be achieved by inkjet-on-demand of UV / thermo-curable resins of different refractive indices before patterning with a template, or using a region-by-region patterning approach, such as using J-FIL TM Nanoimprint technology. It is also possible to adapt different refractive indices in different areas by using a template mask to deposit inorganic high refractive index materials (such as Si3N4, ZrO2, TiO2, etc.), where physical or chemical vapor deposition processes (such as evaporation, sputtering, PECVD, ALD, etc.) can be used for deposition. As an example, in Figure 3D In the embodiment of the present invention, CPE 340 can be manufactured so that region 342 has a first refractive index and region 346 has a second refractive index different from the first refractive index. Thus, gratings corresponding to various grating vectors can be defined for different refractive indices in different regions.

[0130] Figure 4Ais a simplified k-space diagram showing the field of view and CPE grating vectors of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 4B is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 4C yes Figure 4B A simplified plan view of the user side of the eyepiece waveguide with multi-directional emission is shown. In addition to the ICG and CPE regions of the eyepiece waveguide, Figure 4B and 4C The fan angle of light launched into the eyepiece waveguide using ICG is also shown. For comparison, Figure 4A shows the raster vector corresponding to the CPE, and Figure 3A The grating vector (ie, emission vector) corresponding to the ICG is shown.

[0131] refer to Figure 4A The k-space representation of the CPE grating shown and Figure 4B and 4C The plan view of the eyepiece waveguide is shown in Figure 4B As shown, blue light emitted toward the upper left portion of CPE 410 and incident on the grating in region 412 is diffracted as shown by grating vector k1 and propagates toward the center portion of the eyepiece waveguide, where it interacts with the grating coupled to the user side of CPE 4250 (i.e., region 424) and is coupled out as shown by grating vector k2. Figure 4B As shown, the grating periodicity in region 412 is characterized by a smaller grating periodicity, e.g., 525 nm / ~1.9 ≈ 276 nm, compared to the grating periodicity in region 414 (e.g., 525 nm / ~1.5 ≈ 350 nm). Although for clarity, the grating periodicity in region 412 is characterized by a smaller grating periodicity, e.g., 525 nm / ~1.5 ≈ 350 nm. Figure 4C Different grating periodicities are not shown in other figures including FIG. 1 , but it will be appreciated that the grating periodicity associated with different grating vectors will vary appropriately depending on the particular application.

[0132] like Figure 4C As shown, the green and red light emitted toward the lower left portion of CPE 410 and incident on the grating in region 424 coupled to the user side of CPE 420 is diffracted as shown by grating vector k2 and is coupled out as shown by grating vector k3 when interacting with the grating coupled to the world side (i.e., region 414) of CPE 410. Figure 4B and 4C As shown, this embodiment utilizes gratings disposed on both the world and user sides of the eyepiece waveguide. It should be noted that the grating height need not be constant, but may, for example, increase across the CPE in a continuous or discrete manner, including gradient regions.

[0133] Since the eyepiece waveguide is designed for green wavelengths, blue light in blue FOV 331 is diffracted along grating vector k1 in region 412, causing blue FOV 430 to be within the annular region. Therefore, outcoupling will result in blue FOV 430 being coupled out to the user without limiting the FOV, as indicated by grating vector k2. Red light in red FOV 311 and green light in green FOV 313 are diffracted along grating vector k2 in region 424 coupled to the user side of the eyepiece waveguide to form red FOV 440 and green FOV 442, both of which are within the annular region. Upon interaction with the grating in region 414 coupled to the world side of the eyepiece waveguide, outcoupling occurs as indicated by grating vector k3, resulting in outcoupling of red FOV 440 and green FOV 442 without limiting the FOV. It should be noted that the k-space map is referenced to the green wavelength, therefore the raster vectors start and end at the center of the green FOV.

[0134] although Figure 4C Blue light is shown being coupled in by blue ICG 320 coupled to the user side of CPE 420 and diffracted into region 422, but this is not required and in some embodiments blue ICG 406 is optional.

[0135] One benefit provided by embodiments of the present invention utilizing a multi-directional emission design is that the number of bounces for red and blue wavelengths is equalized. Figure 2C As shown, due to multiple bounces, the light with momentum close to the inner circle in the ring interacts strongly with the grating. Due to the grazing incidence angle, the light with momentum close to the outer circle interacts weakly with the grating. For the unidirectional emission design, the red FOV is close to the outer circle, while the blue FOV is close to the inner circle, resulting in a large difference in their interaction with the CPE grating, ultimately leading to uneven display.

[0136] for Figure 4A In the multi-directional emission design, the red FOV 440 and the blue FOV 331 are both located close to the outer circle of r=n=2, which greatly reduces this difference based on the number of bounces within the waveguide.

[0137] In addition to implementing the diffractive structure shown on the other side of the eyepiece waveguide as shown, the diffractive structure can also be implemented on both sides of the eyepiece waveguide. As an example, Figure 3D The diffractive structures shown can be implemented on both the world side and the user side of the eyepiece waveguide. Figure 4B The diffractive structure shown can be implemented on a first side of the eyepiece waveguide (e.g., the world side or the user side), while Figure 3D The diffractive structure shown can be implemented on the second side of the eyepiece waveguide (e.g., the user side or the world side). Figure 3DThe diffractive structure shown can be implemented on a first side of the eyepiece waveguide (e.g., the world side or the user side), while Figure 4C The diffractive structure shown can be implemented on the second side of the eyepiece waveguide (e.g., the user side or the world side).One of ordinary skill in the art will recognize many variations, modifications, and alternatives.

[0138] Figure 4D is a simplified plan view of the world side of an eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention. Figure 4E yes Figure 4D A simplified plan view of the user side of an eyepiece waveguide including a two-dimensional grating with multi-directional emission is shown. Figure 4D The eyepiece waveguide shown is Figure 4B The eyepiece waveguides shown share common elements, and Figure 4E The eyepiece waveguide shown is Figure 4C The eyepiece waveguides shown share common elements. Figure 4B and 4C In addition to the elements discussed above, region 452 of CPE 450 also includes a grating corresponding to grating vector k4, and region 462 of CPE 460 also includes a grating corresponding to grating vector k5. Figure 4F and 4G As discussed, the addition of gratings corresponding to grating vectors k4 and k5 introduces additional diffraction paths that contribute to diffraction within the eyepiece waveguide plane and outcoupling from the eyepiece waveguide.

[0139] Figure 4F is a diagram showing an embodiment of the present invention Figure 4D and 4E Simplified k-space diagram of the field of view and CPE grating vectors for the eyepiece waveguide with multi-directional emission shown.

[0140] refer to Figure 4F , light coupled in by the red ICG 310 is diffracted into the eyepiece waveguide to produce a red FOV 311. Diffraction by the grating corresponding to grating vector k2 causes the red FOV 311 to be transferred to FOV 471, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k3. If light is not coupled out by grating vector k3, diffraction from the grating corresponding to grating vector k5 causes FOV 471 to be transferred to FOV 472, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k4.

[0141] Diffraction by the grating corresponding to grating vector k3 causes red FOV 311 to transfer to FOV 474 or FOV 475, which are coupled out as a result of diffraction from the gratings corresponding to grating vector k2 and grating vector k5, respectively. If light is not coupled out by grating vector k2 or grating vector k5, diffraction from the grating corresponding to grating vector k4 causes FOV 474 to transfer to FOV 473, and FOV 475 to transfer to FOV 471, which can be coupled out as a result of diffraction from the grating corresponding to grating vector k3. Similar diffraction paths can be described for green FOV 311 and blue FOV 331. These diffraction paths are merely exemplary and are not an exhaustive list of different diffraction paths provided by embodiments of the present invention.

[0142] Figure 4G is a diagram showing another embodiment according to the present invention Figure 4D and 4E Simplified k-space diagram of the field of view and CPE grating vectors for the eyepiece waveguide with multi-directional emission shown.

[0143] refer to Figure 4G , light coupled in by the red ICG 310 is diffracted into the eyepiece waveguide to produce a red FOV 311. Diffraction by the grating corresponding to grating vector k2 causes the red FOV 311 to be transferred to FOV 480, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k3. If light is not coupled out by grating vector k3, diffraction from the grating corresponding to grating vector k4 causes FOV 480 to be transferred to FOV 486, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k5 or a transfer of FOV 480 to FOV 481. Diffraction from the grating corresponding to grating vector k3 will cause FOV 481 to be transferred to FOV 482, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k4. Alternatively, diffraction from the grating corresponding to grating vector k1 will cause FOV 481 to shift to FOV 483, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k5. If light is not coupled out by grating vector k5, diffraction from the grating corresponding to grating vector k4 causes FOV 483 to shift to FOV 484, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k3.

[0144] Returning to FOV 480, diffraction by the grating corresponding to grating vector k5 causes FOV 480 to shift to FOV 482, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k4. If light is not coupled out by grating vector k4, diffraction from the grating corresponding to grating vector k2 causes FOV 482 to shift to FOV 484, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k3. Returning to FOV 486, diffraction by the grating corresponding to grating vector k1 causes FOV 486 to shift to FOV 485, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k2. Similarly, diffraction by the grating corresponding to grating vector k1 causes FOV 480 to shift to FOV 484, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k3. If light is not coupled out by grating vector k3, diffraction from the grating corresponding to grating vector k2 causes FOV 484 to shift to FOV 482, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k4, or diffraction from the grating corresponding to grating vector k4 causes FOV 484 to shift to FOV 483, which may be coupled out as a result of diffraction from the grating corresponding to grating vector k5. Similar diffraction paths can be described for green FOV 311 and blue FOV 331. Again, these diffraction paths are merely exemplary and are not an exhaustive list of different diffraction paths provided by embodiments of the present invention.

[0145] Reference again Figure 3D In a single-sided design, gratings corresponding to grating vector k4 and grating vector k5 may be added to region 342 of CPE 350. In a double-sided design, gratings corresponding to grating vector k4 may be added to region 342 of CPE 340 on either the world side or the user side, and gratings corresponding to grating vector k5 may be added to region 342 of CPE 340 on either the user side or the world side to implement two-dimensional gratings in regions 342 and 346. The addition of gratings corresponding to grating vector k4 and grating vector k5 introduces additional diffraction paths that contribute to diffraction in the plane of the eyepiece waveguide and outcoupling from the eyepiece waveguide in both single-sided and double-sided designs.

[0146] Figures 5A-5C The normalized efficiency distributions for red, green, and blue wavelengths for a unidirectional emission design according to an embodiment of the present invention are shown respectively. In these figures, the optical performance of the waveguide architecture is analyzed by analogy to Figure 1C The eyepiece waveguide shown is characterized. Figures 5A-5CThe efficiency distribution of the unidirectional emission design within a 30°x30° field of view is shown for red, green and blue wavelengths respectively.

[0147] refer to Figure 5A , showing the user side eye movement frame efficiency (U EBE ) and world side eye movement frame efficiency (W EBE ). EBE and W EBE The percentage of the total incident power from the projector on either side of the eyepiece that ultimately reaches the eyebox plane at the nominal distance of the eye from the waveguide. The efficiency distribution is non-uniform because light rays corresponding to different incident angles are diffused within the waveguide and interact with the grating differently. As shown by U inner80 The uniformity of the display can be expressed as the 80-20 percentile for the inner 80% of the field of view. inner80 It is the ratio of the difference between the 80th and 20th percentiles to the 50th percentile (i.e., the median). inner80 The lower the value, the better the uniformity. Figure 5B shows the U for the green wavelength EBE and W EBE ,and Figure 5C shows the blue wavelength U EBE and W EBE .U inner80 For red wavelengths it is equal to 1.868, for green wavelengths it is equal to 0.699, and for blue wavelengths it is equal to 2.110. Figure 5A Region R1 and Figure 5C Regions R2 and R3 in represent cropped portions of the field of view where the light intensity is zero.

[0148] Figures 5D-5F The normalized efficiency distributions for red, green, and blue wavelengths for a multi-directional emission design according to an embodiment of the present invention are shown in FIG. Figure 3A / 3B is used to characterize the eyepiece waveguide. Figures 5A-5C The efficiency distribution of the multi-directional emission design within a 30°x30° field of view is shown for red, green and blue wavelengths respectively.

[0149] Will Figures 5D-5F and Figures 5A-5C For comparison, U inner80 For red wavelengths it is equal to 1.184, for green wavelengths it is equal to 1.388, and for blue wavelengths it is equal to 0.0892. Importantly, Figures 5A-5C The regions marked R1, R2, and R3 in the figure show the cropping of the 30° x 30° field of view for the unidirectional emission design, while Figures 5D-5FThere is no such cropping in , suggesting that the field of view limitation is overcome by the multi-directional emission architecture.

[0150] Although the efficiency distribution is non-uniform, the color correction algorithm adjusts the weights corresponding to different incident angles within the FOV to obtain good color (white) uniformity for AR display. In addition, the center-peak ratio (i.e., the efficiency at the center divided by the peak efficiency, ideal value = 1) indicates the centrality of the efficiency distribution within the FOV.

[0151] Table 1 gives another comparison between the unidirectional and multi-directional launch designs, where the maximum possible FOV is calculated based on the k-space map, ensuring that the square FOV is completely within the annular domain of the 2.0 refractive index waveguide. For these calculations, we assume that for both the unidirectional and multi-directional launch designs, the ICG or projector is located above the center of the temple side to achieve a larger real-world FOV, equal horizontal (H) and vertical (V) range of the FOV, and a constant refractive index for all wavelengths.

[0152] As evident from Table 1, the multi-directional emission design has a clear fundamental advantage in terms of the maximum achievable digital field of view.

[0153]

[0154]

[0155] Table 1

[0156] It should be noted that the maximum achievable diagonal FOV for both designs will change for light emitted into the waveguide via the projector using different ICG placements (i.e., different emission angles). However, it can be shown that the multi-directional emission design always produces a larger possible field of view than the unidirectional emission design.

[0157] about Figures 6A-16D , shows k-space representations of ICG gratings and CPE gratings, and a CPE layout showing the locations of the corresponding gratings for several multi-directional launch waveguide architectures. In addition, the sequence of minimum diffraction events to direct projector light of red, green, or blue wavelengths to the user's eye is discussed. The k-space representation is for a 30x 30 FOV with an eyepiece waveguide with a refractive index of n=2.0 and three separate ICG pupils for red, green, and blue wavelengths. The grating vectors are normalized with respect to the green free-space momentum.

[0158] Fig. 6A is a simplified k-space diagram showing the field of view and ICG grating vectors of the first eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 6B is a simplified k-space diagram showing the field of view and CPE grating vectors of the first eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 6C is a simplified plan view of the world side of a first eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.6D yes Figure 6C A simplified plan view of the user side of the first eyepiece waveguide with multi-directional emission is shown.

[0159] First reference Figure 6C and 6D The first eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, wherein Figure 6C The individual ICG pupils coupled to the world side of the eyepiece waveguide are shown as red ICG 610, green ICG 612, and blue ICG 614. Fig.6D The red ICG 611, green ICG 613, and blue ICG 615 shown coupled to the user side of the eyepiece waveguide are used in combination. Thus, these six ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors of the various ICGs designed for green wavelengths are different for blue light (and blue ICG) than for red and green light (and red and green ICG). Although Fig.6D The illustrated embodiment includes red ICG 611, green ICG 613, and blue ICG 615 coupled to the user side of the eyepiece waveguide, but this is not required and in some embodiments, red ICG 611, green ICG 613, and blue ICG 615 are optional.

[0160] refer to Fig. 6A , raster vector k H represents diffraction at larger distances (height) in k-space, and the grating vector k L represents the diffraction at smaller distances (low) in k-space. Therefore, corresponding to the grating vector k L The gratings of are characterized by the same grating size (ie, the same grating periodicity, e.g., 525 nm / ~1.5≈350 nm), and correspond to the grating vector k H The gratings of the eyepiece waveguide are characterized by a larger grating size, (i.e., a smaller grating periodicity, such as 525 nm / ~1.9≈276 nm). Therefore, for the red ICG 610 and green ICG 612 coupled to the world side of the eyepiece waveguide or the red IGG 611 and green ICG 613 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide, as indicated by the grating vector k L630 for red wavelengths and a green FOV 632 for green wavelengths. Both FOVs are located within the annular region between r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using a blue ICG 614 coupled to the world side of the eyepiece waveguide or a blue ICG 615 coupled to the user side of the eyepiece waveguide is shown as k H 634. The FOV is diffracted as shown. Therefore, for the blue ICG 614 coupled to the world side of the eyepiece waveguide and the blue ICG 615 coupled to the user side of the eyepiece waveguide, the light in the center of the FOV is diffracted into the eyepiece waveguide to produce a blue FOV 634 for blue wavelengths. This FOV is located within the annular region between r=n=1 and r=n=2. Therefore, this wavelength-specific multi-directional launch architecture is able to achieve a full 30° x 30° FOV because the respective barrel boxes corresponding to the red FOV 630, green FOV 632, and blue FOV 634 corresponding to TIR light are completely located within the annular region.

[0161] refer to Figure 6C , the orientation of the gratings in the red ICG 610 and green ICG 612 and the red ICG 611 and green ICG 613 is oriented so that the red light and the green light are emitted into the eyepiece waveguide toward the region 644 of the CPE 640 and the region 654 of the CPE 650. The orientation of the gratings in the blue ICG 611 and the blue ICG 620 is oriented so that the blue light is emitted into the eyepiece waveguide toward the region 642 of the CPE 640 on the world side and the region 652 of the CPE 650 on the user side.

[0162] refer to Figure 6B and 6D , red and green light emitted toward region 654 of CPE 650 is incident on the grating corresponding to grating vector k2, thereby diffracting in the plane of the eyepiece waveguide (i.e., diffracting laterally in the eyepiece waveguide). As a result, red FOV 630 is transferred to red FOV 631 in k-space, and green FOV 632 is transferred to green FOV 633 in k-space. Diffraction in region 644 from the grating corresponding to grating vector k3 causes outcoupling from the eyepiece waveguide. Blue light emitted toward region 642 in CPE 640 and region 652 in CPE 650 is incident on the grating corresponding to grating vector k1 in regions 642 and 652, thereby diffracting in the plane of the eyepiece waveguide. As a result, blue FOV 634 is transferred to blue FOV 635 in k-space. Diffraction in region 654 from the grating corresponding to grating vector k2 causes outcoupling from the eyepiece waveguide. Therefore, the diffraction paths of the red and green wavelengths are k L→k2→k3, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. The diffraction path for blue wavelengths is k H →k1→k2.

[0163] like Fig. 6A and 6B As shown, the red FOV 630 / 631, the green FOV 632 / 633 and the blue FOV 634 / 635 are all located in the annular region between r = n = 1 and r = n = 2. Therefore, propagation in the plane of the eyepiece waveguide and outcoupling are performed without cropping the FOV.

[0164] Fig. 7A is a simplified k-space diagram showing the field of view and ICG grating vectors of a second eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 7B is a simplified k-space diagram showing the field of view and CPE grating vectors of a second eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 7C is a simplified plan view of the world side of a second eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.7D yes Figure 7C A simplified plan view of the user side of a second eyepiece waveguide with multi-directional emission is shown.

[0165] First reference Figure 7C and 7D The second eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a single ICG pupil (such as Figure 7C The first ICG 710 is shown in Fig.7D The embodiment shown is used in conjunction with a second ICG 711 coupled to the user side of the eyepiece waveguide. Thus, the two ICGs are used to couple light from the projector into the eyepiece waveguide. In the embodiment shown, both ICGs are located at the same position in the xy plane (also called the transverse plane), and all wavelengths (e.g., red wavelengths, green wavelengths, and blue wavelengths) are emitted from each ICG, with different wavelengths emitted in different directions.

[0166] In an embodiment, the first ICG 710 and the second ICG 711 are each implemented as a two-dimensional diffraction structure (eg, a two-dimensional grating, a nanostructure, etc.) having a grating vector k H and k L In another embodiment, the first ICG 710 emits light in the first direction (e.g., k H ) and the second ICG 711 emits light in a second direction (eg, k L). The single ICG design is particularly suitable for use with micro-LED displays (where the primary colors may not be easily separated spatially). Therefore, light from the micro-LED display can be imaged into a single ICG.

[0167] refer to Fig. 7A , raster vector k H represents diffraction at larger distances (height) in k-space, and the grating vector k L = 1, which represents diffraction at smaller distances (low) in k-space. Therefore, the first ICG 710 coupled to the world side of the eyepiece waveguide and the second ICG 711 coupled to the user side of the eyepiece waveguide will couple in multiple wavelengths and a first range of directions (corresponding to the grating vector k H ) to generate red FOV 720, green FOV 722 and blue FOV 724, and couple in multiple wavelengths and a second direction range (corresponding to the grating vector k L ) to produce red FOV 721, green FOV 723, and blue FOV 725 (to the extent that some or all of these FOVs are supported by the eyepiece waveguide). Fig. 7A , blue FOV 724, green FOV 723, and red FOV 721 are located within the annular region between r = n = 1 and r = n = 2. Red FOV 720, green FOV 722, and blue FOV 725 include portions within the annular region between r = n = 1 and r = n = 2. It should be noted that changes in the refractive index of the eyepiece waveguide material (e.g., a refractive index factor of 2.5) will result in changes in the amount of FOV contained within the annular region.

[0168] refer to Figure 7B, light present in the red FOV 720, the green FOV 722, and the blue FOV 724 is diffracted in the region 742 of the CPE 740 coupled to the world side and the region 752 of the CPE 750 coupled to the user side, and is incident on the grating corresponding to the grating vector k1, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 720 is transferred to the red FOV 731 in k-space, the green FOV 722 is transferred to the green FOV 733 in k-space, and the blue FOV 724 is transferred to the blue FOV 735 in k-space. Diffraction in the region 754 from the CPE 750 corresponding to the grating vector k2 results in outcoupling from the eyepiece waveguide. Light present in the red FOV 721, the green FOV 723, and the blue FOV 724 is diffracted in the region 754 of the CPE 750 coupled to the user side and is incident on the grating corresponding to the grating vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 721 is transferred to the red FOV 730 in k-space, the green FOV 723 is transferred to the green FOV 732 in k-space, and the blue FOV 725 is transferred to the blue FOV 734 in k-space. Diffraction in the region 744 from the CPE 740 corresponding to the grating vector k3 results in outcoupling from the eyepiece waveguide.

[0169] Therefore, the first ICG 710 and the second ICG 711 are connected by the grating vector k H The diffraction paths of the red, green and blue wavelengths coupled in the direction are k H →k1→k2, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. L The diffraction paths of the red, green and blue wavelengths coupled in the direction are k L →k2→k3.

[0170] Fig. 8A is a simplified k-space diagram showing the field of view and ICG grating vectors of a third eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 8B is a simplified k-space diagram showing the field of view and CPE grating vectors of a third eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Figure 8C is a simplified plan view of the world side of a third eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.8D yes Figure 8C A simplified plan view of the user side of the third eyepiece waveguide with multi-directional emission is shown.

[0171] First reference Figure 8C and8D The third eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a separate ICG pupil (such as Figure 8C 810, green ICG 812 and blue ICG 814) and Fig.8D The red ICG 811, green ICG 813, and blue ICG 815 shown coupled to the user side of the eyepiece waveguide are used in combination. Thus, these six ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors of the various ICGs designed for green wavelengths are different for blue light (and blue ICG) than for red and green light (and red and green ICGs). Although Fig.8D The illustrated embodiment includes red ICG 811, green ICG 813, and blue ICG 815 coupled to the user side of the eyepiece waveguide, but this is not required and in some embodiments, red ICG 811, green ICG 813, and blue ICG 815 are optional.

[0172] refer to Fig. 8A , raster vector k H Represents diffraction at larger distances (height) in k-space, and the grating vector k L represents the diffraction at smaller distances (low) in k-space. Therefore, corresponding to the grating vector k L The gratings of are characterized by the same grating size (ie, the same grating periodicity, e.g., 525 nm / ~1.5≈350 nm), and correspond to the grating vector k H The gratings of the eyepiece waveguide are characterized by a larger grating size (i.e., a smaller grating periodicity, such as 525 nm / ~1.9≈276 nm). Therefore, for the red ICG 810 and green ICG 812 coupled to the world side of the eyepiece waveguide, or the red IGG 811 and green ICG 813 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide, as indicated by the grating vector k L 830 for red wavelengths and a green FOV 832 for green wavelengths. Both FOVs are located within the annular region between r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using a blue ICG 814 coupled to the world side of the eyepiece waveguide or a blue ICG 815 coupled to the user side of the eyepiece waveguide is shown as k H814 coupled to the world side and the blue ICG 815 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide to produce a blue FOV 834 for blue wavelengths. This FOV is located within the annular region between r=n=1 and r=n=2. Therefore, this wavelength-specific multi-directional launch architecture is able to achieve a full 30° x 30° FOV because the respective barrel-shaped boxes corresponding to the red FOV 830, green FOV 832, and blue FOV 834 corresponding to TIR light are completely located within the annular region.

[0173] refer to Figure 8C , the orientation of the gratings in the red ICG 810 and green ICG 812 and the red ICG 811 and green ICG 813 is oriented so that the red light and the green light are emitted into the eyepiece waveguide toward the region 842 of the CPE 840 on the world side and the region 852 of the CPE 850 on the user side. The orientation of the gratings in the blue ICG 811 and blue ICG 820 is oriented so that the blue light is emitted into the eyepiece waveguide toward the region 844 of the CPE 840 on the world side and the region 854 of the CPE 850 on the user side.

[0174] refer to Figure 8B and 8D , red and green light emitted toward region 852 of CPE 850 is incident on the grating corresponding to grating vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, red FOV 830 is transferred to red FOV 831 in k-space, and green FOV 832 is transferred to green FOV 833 in k-space. Diffraction in region 842 from the grating corresponding to grating vector k3 causes outcoupling from the eyepiece waveguide. Blue light emitted toward region 844 in CPE 840 and region 854 in CPE 850 is incident on the grating corresponding to grating vector k1 in regions 844 and 854, thereby diffracting in the plane of the eyepiece waveguide. As a result, blue FOV 834 is transferred to blue FOV 835 in k-space. Diffraction in region 852 from the grating corresponding to grating vector k2 causes outcoupling from the eyepiece waveguide. Therefore, the diffraction paths of the red and green wavelengths are k L →k2→k3, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. The diffraction path for blue wavelengths is k H →k1→k2. It should also be noted that regions 844 and 854 of the CPE have the same grating, and one or both of them can be used in this multi-directional transmission architecture. When only one of them is present, i.e., 854 or 844, the CPE on the opposite side will have an extended grating region 842 or 852, respectively.

[0175] like Fig. 8A and 8B As shown, the red FOV 830 / 831, the green FOV 832 / 833 and the blue FOV 834 / 835 are all located in the annular region between r = n = 1 and r = n = 2. Therefore, propagation in the plane of the eyepiece waveguide as well as outcoupling are performed without cropping the FOV.

[0176] Fig.9A is a simplified k-space diagram showing the field of view and ICG grating vectors of a fourth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 9B is a simplified k-space diagram showing the field of view and CPE grating vectors of a fourth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 9C is a simplified plan view of the world side of a fourth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.9D yes Fig. 9C Simplified plan view of the user side of the fourth eyepiece waveguide with multi-directional emission shown.

[0177] First reference Fig. 9C and 9D The fourth eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a single ICG pupil (such as Fig. 9C The first ICG 910 is shown in Fig.9D The second ICG 911 shown coupled to the user side of the eyepiece waveguide is used in conjunction. Thus, the two ICGs are used to couple light from the projector into the eyepiece waveguide. In the embodiment shown, both ICGs are located at the same position in the xy plane, and all wavelengths (e.g., red wavelengths, green wavelengths, and blue wavelengths) are emitted from each ICG, with different wavelengths emitted in different directions.

[0178] In an embodiment, the first ICG 910 and the second ICG 911 are each implemented as a two-dimensional diffraction structure (eg, a two-dimensional grating, a nanostructure, etc.) having a grating vector k H and k L In another embodiment, the first ICG 910 emits light in the first direction (e.g., k H ) and the second ICG 911 emits light in a second direction (eg, k L ). The single ICG design is particularly suitable for use with micro-LED displays (where the primary colors may not be easily separated spatially). Therefore, light from the micro-LED display can be imaged into a single ICG.

[0179] refer to Fig.9A , raster vector kH represents diffraction at larger distances (height) in k-space, and the grating vector k L = 910, which is coupled to the world side of the eyepiece waveguide, and the second ICG 911, which is coupled to the user side of the eyepiece waveguide, will couple in multiple wavelengths and a first range of directions (corresponding to the grating vector k H ) to generate red FOV 920, green FOV 922 and blue FOV 924, and couple in multiple wavelengths and a second direction range (corresponding to the grating vector k L ) to produce red FOV 921, green FOV 923, and blue FOV 925 (to the extent that some or all of these FOVs are supported by the eyepiece waveguide). Fig.9A , blue FOV 925, green FOV 922, and red FOV 920 are located within the annular region between r = n = 1 and r = n = 2. Red FOV 921, green FOV 923, and blue FOV 924 include portions within the annular region between r = n = 1 and r = n = 2. It should be noted that changes in the refractive index of the eyepiece waveguide material (e.g., a refractive index factor of 2.5) will result in changes in the amount of FOV contained within the annular region.

[0180] refer to Fig. 9B , light present in the red FOV 920, the green FOV 922, and the blue FOV 924 is diffracted in the region 952 of the CPE 950 coupled to the user side, and is incident on the grating corresponding to the grating vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 920 is transferred to the red FOV 931 in k-space, the green FOV 922 is transferred to the green FOV 933 in k-space, and the blue FOV 924 is transferred to the blue FOV 935 in k-space. Diffraction in the region 942 from the CPE 940 corresponding to the grating vector k3 results in outcoupling from the eyepiece waveguide. Light present in the red FOV 921, the green FOV 923, and the blue FOV 925 is diffracted in the region 944 of the CPE 940 coupled to the world side and the region 654 of the CPE 950 coupled to the user side, and is incident on the grating corresponding to the grating vector k1, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 921 is transferred in k-space to the red FOV 930, the green FOV 923 is transferred in k-space to the green FOV 932, and the blue FOV 924 is transferred in k-space to the blue FOV 934. Diffraction in the region 942 from the CPE 940 of the grating corresponding to the grating vector k2 results in outcoupling from the eyepiece waveguide.

[0181] Therefore, the first ICG 910 and the second ICG 911 are connected by the grating vector k L The diffraction paths of the red, green and blue wavelengths coupled in the direction are k L →k1→k2, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. H The diffraction paths of the red, green and blue wavelengths coupled in the direction are k H →k2→k3. Similar to the above designs, one of the grating regions, e.g., region 944 or region 954, may be considered optional and may be replaced by a grating region on the corresponding world side or user side of the eyepiece waveguide.

[0182] Fig. 10A is a simplified k-space diagram showing the field of view and ICG grating vectors of a fifth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 10B is a simplified k-space diagram showing the field of view and CPE grating vectors of the fifth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 10C is a simplified plan view of the world side of a fifth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 10D yes Fig. 10C A simplified plan view of the user side of the fifth eyepiece waveguide with multi-directional emission is shown.

[0183] First reference Fig. 10C and 10D The fifth eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a separate ICG pupil (such as Fig. 10C The red ICG 1010, green ICG 1012 and blue ICG 1014 are shown in FIG. Fig. 10D The red ICG 1011, green ICG 1013, and blue ICG 1015 shown coupled to the user side of the eyepiece waveguide are used in combination. Thus, these six ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors of the various ICGs designed for green wavelengths are different for blue light (and blue ICG) than for red and green light (and red and green ICGs). Although Fig. 10D The illustrated embodiment includes red ICG 1011, green ICG 1013, and blue ICG 1015 coupled to the user side of the eyepiece waveguide, but this is not required and in some embodiments, red ICG 1011, green ICG 1013, and blue ICG 1015 are optional.

[0184] refer to Fig. 10A , raster vector k H Represents diffraction at larger distances (height) in k-space, and the grating vector k L represents the diffraction at smaller distances (low) in k-space. Therefore, corresponding to the grating vector k L The gratings of are characterized by the same grating size (ie, the same grating periodicity, e.g., 525 nm / ~1.5≈350 nm), and correspond to the grating vector k H The gratings of the eyepiece waveguide are characterized by a larger grating size (i.e., a smaller grating periodicity, such as 525 nm / ~1.9≈276 nm). Therefore, for the red ICG 1010 and green ICG 1012 coupled to the world side of the eyepiece waveguide, or the red IGG 1011 and green ICG 1013 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide, as indicated by the grating vector k L 1030 for red wavelengths and a green FOV 1032 for green wavelengths. Both FOVs are located within the annular region between r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using a blue ICG 1014 coupled to the world side of the eyepiece waveguide or a blue ICG 1015 coupled to the user side of the eyepiece waveguide is shown as k H 1034 for the blue wavelengths. This FOV is located within the annular region between r=n=1 and r=n=2. Thus, this wavelength-specific multi-directional launch architecture enables a full 30° x 30° FOV because the respective barrel-shaped boxes corresponding to the red FOV 1030, green FOV 1032, and blue FOV 1034 corresponding to TIR light are completely located within the annular region.

[0185] refer to Fig. 10C , the orientation of the gratings in the red ICG 1010 and the green ICG 1012 and the red ICG 1011 and the green ICG 1013 is oriented so that the red light and the green light are emitted into the eyepiece waveguide toward the area 1042 of the CPE 1040 on the world side and the area 1052 of the CPE 1050 on the user side. The orientation of the gratings in the blue ICG 1014 and the blue ICG 1015 is oriented so that the blue light is emitted into the eyepiece waveguide toward the area 1044 of the CPE 1040 on the world side and the area 1054 of the CPE 1050 on the user side.

[0186] refer to Fig. 10B and 10D, red and green light emitted toward region 1052 of CPE 1050 is incident on the grating corresponding to grating vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, red FOV 1030 is transferred to red FOV 1031 in k-space, and green FOV 1032 is transferred to green FOV 1033 in k-space. Diffraction in region 1042 from the grating corresponding to grating vector k3 causes outcoupling from the eyepiece waveguide. Blue light emitted toward region 1044 in CPE 1040 and region 1054 in CPE 1050 is incident on the grating corresponding to grating vector k1 in regions 1044 and 1054, thereby diffracting in the plane of the eyepiece waveguide. As a result, blue FOV 1034 is transferred to blue FOV 1035 in k-space. Diffraction in region 1052 from the grating corresponding to grating vector k2 results in outcoupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths are k L →k2→k3, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. The diffraction path for blue wavelengths is k H →k1→k2.

[0187] like Fig. 10A and 10B As shown, the red FOV 1030 / 1031, the green FOV 1032 / 1033, and the blue FOV 1034 / 1035 are all located in the annular region between r = n = 1 and r = n = 2. Therefore, propagation in the plane of the eyepiece waveguide and outcoupling are performed without cropping the FOV.

[0188] Fig.11A is a simplified k-space diagram showing the field of view and ICG grating vectors of the sixth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 11B is a simplified k-space diagram showing the field of view and CPE grating vectors of the sixth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 11C is a simplified plan view of the world side of a sixth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.11D yes Fig. 11C A simplified plan view of the user side of the sixth eyepiece waveguide with multi-directional emission is shown.

[0189] First reference Fig. 11C and 11D The sixth eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a single ICG pupil (such as Fig. 11C The first ICG 1110 is shown in Fig.11DThe embodiment shown is used in conjunction with a second ICG 1111 coupled to the user side of the eyepiece waveguide. Thus, the two ICGs are used to couple light from the projector into the eyepiece waveguide. In the embodiment shown, both ICGs are located at the same position in the xy plane, and all wavelengths (e.g., red, green, and blue) are emitted from each ICG, with different wavelengths emitted in different directions.

[0190] In an embodiment, the first ICG 1110 and the second ICG 1111 are each implemented as a two-dimensional diffraction structure (eg, a two-dimensional grating, a nanostructure, etc.) having a grating vector k H and k L In another embodiment, the first ICG 1110 emits light in the first direction (e.g., k H ) and the second ICG 1111 emits light in a second direction (eg, k L ). The single ICG design is particularly suitable for use with micro-LED displays (where the primary colors may not be easily separated spatially). Therefore, light from the micro-LED display can be imaged into a single ICG.

[0191] refer to Fig.11A , raster vector k H represents diffraction at larger distances (height) in k-space, and the grating vector k L = 1, which represents diffraction at smaller distances (low) in k-space. Therefore, the first ICG 1110 coupled to the world side of the eyepiece waveguide and the second ICG 1111 coupled to the user side of the eyepiece waveguide will couple in multiple wavelengths and a first range of directions (corresponding to the grating vector k H ) to generate red FOV 1120, green FOV 1122 and blue FOV 1124, and couple in multiple wavelengths and a second direction range (corresponding to the grating vector k L ) to produce red FOV 1121, green FOV 1123, and blue FOV 1125 (to the extent that some or all of these FOVs are supported by the eyepiece waveguide). Fig.11A , blue FOV 1125, green FOV 1123, green FOV 1122, and red FOV 1120 are located within the annular region between r = n = 1 and r = n = 2. Red FOV 1121 and blue FOV 1124 include portions within the annular region between r = n = 1 and r = n = 2. It should be noted that changes in the refractive index of the eyepiece waveguide material (e.g., a refractive index factor of 2.5) will result in changes in the amount of FOV contained within the annular region.

[0192] refer to Fig. 11B, light present in the red FOV 1120, the green FOV 1122, and the blue FOV 1124 is diffracted in the region 1152 of the CPE 1150 coupled to the user side, and is incident on the grating corresponding to the grating vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 1120 is transferred to the red FOV 1131 in k-space, the green FOV 1122 is transferred to the green FOV 1133 in k-space, and the blue FOV 1124 is transferred to the blue FOV 1135 in k-space. Diffraction in the region 1142 of the CPE 1140 from the grating corresponding to the grating vector k3 results in outcoupling from the eyepiece waveguide. Light present in the red FOV 1121, the green FOV 1123, and the blue FOV 1125 is diffracted in the region 1144 of the CPE 1140 coupled to the world side and the region 1154 of the CPE 1150 coupled to the user side, and is incident on the grating corresponding to the grating vector k1, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 1121 is transferred in k-space to the red FOV 1130, the green FOV 1123 is transferred in k-space to the green FOV 1132, and the blue FOV 1125 is transferred in k-space to the blue FOV 1134. Diffraction in the region 1152 of the CPE 1150 from the grating corresponding to the grating vector k2 results in outcoupling from the eyepiece waveguide.

[0193] Therefore, the first ICG 1110 and the second ICG 1111 are connected by the grating vector k L The diffraction paths of the red, green and blue wavelengths coupled in the direction are k L →k1→k2, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. H The diffraction paths of the red, green and blue wavelengths coupled in the direction are k H →k2→k3.

[0194] Fig. 12A is a simplified k-space diagram showing the field of view and ICG grating vectors of the seventh eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 12B is a simplified k-space diagram showing the field of view and CPE grating vectors of the seventh eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 12C is a simplified plan view of the world side of a seventh eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.12D yes Fig. 12C A simplified plan view of the user side of the seventh eyepiece waveguide with multi-directional emission is shown.

[0195] First reference Fig. 12C and 12D The seventh eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a separate ICG pupil (such as Fig. 12C 1210, green ICG 1212 and blue ICG 1214) and Fig.12D The red ICG 1211, green ICG 1213, and blue ICG 1215 shown coupled to the user side of the eyepiece waveguide are used in combination. Thus, these six ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors of the various ICGs designed for green wavelengths are the same for blue light (and blue ICG) as for red and green light (and red and green ICGs). Although Fig.12D The illustrated embodiment includes red ICG 1211, green ICG 1213, and blue ICG 1215 coupled to the user side of the eyepiece waveguide, but this is not required and in some embodiments, red ICG 1211, green ICG 1213, and blue ICG 1215 are optional.

[0196] refer to Fig. 12A , raster vector k H represents the diffraction at the first distance in k-space, and the grating vector k L represents diffraction at the second distance in k-space. Thus, for red ICG 1210 and green ICG 1212 coupled to the world side of the eyepiece waveguide, or red IGG 1211 and green ICG 1213 coupled to the user side of the eyepiece waveguide, light at the center of the FOV is diffracted into the eyepiece waveguide as indicated by the grating vector k L 1230 for red wavelengths and a green FOV 1232 for green wavelengths. Both FOVs are located within the annular region between r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using a blue ICG 1214 coupled to the world side of the eyepiece waveguide or a blue ICG 1215 coupled to the user side of the eyepiece waveguide is shown as k H1234 for the blue wavelengths. This FOV is located within the annular region between r=n=1 and r=n=2. Thus, this wavelength-specific multi-directional launch architecture enables a full 30° x 30° FOV, as the respective barrel-shaped boxes corresponding to the red FOV 1230, green FOV 1232, and blue FOV 1234 corresponding to TIR light are completely located within the annular region.

[0197] refer to Fig. 12C , the orientation of the gratings in the red ICG 1210 and the green ICG 1212 and the red ICG 1211 and the green ICG 1213 is oriented so that the red light and the green light are emitted into the eyepiece waveguide toward the area 1242 of the CPE 1240 on the world side and the area 1252 of the CPE 1250 on the user side. The orientation of the gratings in the blue ICG 1214 and the blue ICG 1215 is oriented so that the blue light is emitted into the eyepiece waveguide toward the area 1246 of the CPE 1240 on the world side and the area 1256 of the CPE 1250 on the user side. Fig. 10C and 10D Compared to the eyepiece waveguide layout shown, regions 1242, 1246, 1252, and 1256 have gratings corresponding to grating vector k1. Region 1244 having a grating corresponding to grating vector k3 is disposed between regions 1242 and 1246, and region 1254 having a grating corresponding to grating vector k2 is disposed between regions 1252 and 1256.

[0198] refer to Fig. 12B and 12D, red light and green light emitted toward region 1242 of CPE 1240 and region 1252 of CPE 1250 are incident on the grating corresponding to grating vector k1, thereby diffracting in the plane of the eyepiece waveguide. As a result, red FOV 1230 is transferred to red FOV 1231 in k-space, and green FOV 1232 is transferred to green FOV 1233 in k-space. Diffraction in region 1244 of CPE 1240 from the grating corresponding to grating vector k3 causes outcoupling from the eyepiece waveguide. Blue light emitted toward region 1246 in CPE 1240 and region 1256 in CPE 1250 is incident on the grating corresponding to grating vector k1 in region 1246 and region 1256, thereby diffracting in the plane of the eyepiece waveguide. As a result, blue FOV 1234 is transferred to blue FOV 1235 in k-space. Diffraction in region 1254 of CPE 1250 from the grating corresponding to grating vector k2 results in outcoupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths are k L →k1→k3, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. The diffraction path for blue wavelengths is k H →k1→k2.

[0199] Fig.13A is a simplified k-space diagram showing the field of view and ICG grating vectors of the eighth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 13B is a simplified k-space diagram showing the field of view and CPE grating vectors of the eighth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 13C is a simplified plan view of the world side of an eighth eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.13D yes Fig. 13C A simplified plan view of the user side of the eighth eyepiece waveguide with multi-directional emission is shown.

[0200] First reference Fig. 13C and 13D The eighth eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a single ICG pupil (such as Fig. 13C The first ICG 1310 is shown in Fig.13D 1311 is used in conjunction with a second ICG 1311 coupled to the user side of the eyepiece waveguide as shown. Thus, the two ICGs are used to couple light from the projector into the eyepiece waveguide. In the embodiment shown, both ICGs are located at the same position in the xy plane, and all wavelengths (e.g., red, green, and blue) are emitted from each ICG, with different wavelengths emitted in different directions. Fig. 12C and 12DThe eyepiece waveguide layout shown is similar, with regions 1342, 1346, 1352, and 1356 having gratings corresponding to grating vector k1. Region 1344 having a grating corresponding to grating vector k3 is disposed between regions 1342 and 1346, and region 1354 having a grating corresponding to grating vector k2 is disposed between regions 1352 and 1356.

[0201] In an embodiment, the first ICG 1310 and the second ICG 1311 are each implemented as a two-dimensional diffraction structure (eg, a two-dimensional grating, a nanostructure, etc.) having a grating vector k H and k L In another embodiment, the first ICG 1310 emits light in the first direction (e.g., k H ) and the second ICG 1311 emits light in a second direction (eg, k L ). The single ICG design is particularly suitable for use with micro-LED displays (where the primary colors may not be easily separated spatially). Therefore, light from the micro-LED display can be imaged into a single ICG.

[0202] refer to Fig.13A , raster vector k H represents the diffraction at the first distance in k-space, and the grating vector k L = 1310, which is coupled to the world side of the eyepiece waveguide, and the second ICG 1311, which is coupled to the user side of the eyepiece waveguide, will couple in multiple wavelengths and a first range of directions (corresponding to the grating vector k H ) to generate red FOV 1320, green FOV 1322 and blue FOV 1324, and couple in multiple wavelengths and a second direction range (corresponding to the grating vector k L ) to produce red FOV 1321, green FOV 1323, and blue FOV 1325 (to the extent that some or all of these FOVs are supported by the eyepiece waveguide). Fig.13A , blue FOV 1325, green FOV 1323, green FOV 1322, and red FOV 1320 are located within the annular region between r = n = 1 and r = n = 2. Red FOV 1321 and blue FOV 1324 include portions within the annular region between r = n = 1 and r = n = 2. It should be noted that changes in the refractive index of the eyepiece waveguide material (e.g., a refractive index factor of 2.5) will result in changes in the amount of FOV contained within the annular region.

[0203] refer to Fig. 13B, light present in the red FOV 1320, the green FOV 1322, and the blue FOV 1324 is diffracted in the region 1342 of the CPE 1340 coupled to the world side and the region 1352 of the CPE 1350 coupled to the user side, and is incident on the grating corresponding to the grating vector k1, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 1320 is transferred to the red FOV 1321 in k-space, the green FOV 1322 is transferred to the green FOV 1323 in k-space, and the blue FOV 1324 is transferred to the blue FOV 1325 in k-space. Diffraction in the region 1344 of the CPE 1340 from the grating corresponding to the grating vector k3 results in outcoupling from the eyepiece waveguide. Light present in the red FOV 1321, the green FOV 1323, and the blue FOV 1325 is diffracted in the region 1346 of the CPE 1340 coupled to the world side and the region 1356 of the CPE 1350 coupled to the user side, and is incident on the grating corresponding to the grating vector k1, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 1321 is transferred in k-space to the red FOV 1320, the green FOV 1323 is transferred in k-space to the green FOV 1322, and the blue FOV 1325 is transferred in k-space to the blue FOV 1324. Diffraction in the region 1354 of the CPE 1350 from the grating corresponding to the grating vector k2 results in outcoupling from the eyepiece waveguide.

[0204] Therefore, the first ICG 1310 and the second ICG 1311 are connected by the grating vector k H The diffraction paths of the red, green and blue wavelengths coupled in the direction are k H →k1→k2, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. L The diffraction paths of the red, green and blue wavelengths coupled in the direction are k L →k1→k3.

[0205] Fig.14A is a simplified k-space diagram showing the field of view and ICG grating vectors of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention. Fig. 12B is a simplified k-space diagram showing the field of view and CPE grating vectors of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention. Fig. 14C is a simplified plan view of the world side of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention. Fig.14D yes Fig. 14CA simplified plan view of the user side of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission is shown.

[0206] First reference Fig. 14C and 14D The first eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, wherein a separate ICG pupil (such as Fig. 14C ) and Fig.14D The red ICG 1411, green ICG 1413, and blue ICG 1415 shown coupled to the user side of the eyepiece waveguide are used in combination. Thus, these six ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors for the various ICGs designed for green wavelengths are the same for blue light (and blue ICG) as for red and green light (and red and green ICGs). Although Fig.14D The illustrated embodiment includes red ICG 1411, green ICG 1413, and blue ICG 1415 coupled to the user side of the eyepiece waveguide, but this is not required and in some embodiments, red ICG 1411, green ICG 1413, and blue ICG 1415 are optional.

[0207] refer to Fig.14A , raster vector k H represents the diffraction at the first distance in k-space, and the grating vector k L represents diffraction at the second distance in k-space. Thus, for red ICG 1410 and green ICG 1412 coupled to the world side of the eyepiece waveguide, or red IGG 1411 and green ICG 1413 coupled to the user side of the eyepiece waveguide, light at the center of the FOV is diffracted into the eyepiece waveguide as indicated by the grating vector k L 1430 for red wavelengths and a green FOV 1432 for green wavelengths. Both FOVs are located within the annular region between r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using a blue ICG 1414 coupled to the world side of the eyepiece waveguide or a blue ICG 1415 coupled to the user side of the eyepiece waveguide is shown as k H1434 for the blue wavelengths. This FOV is located within the annular region between r=n=1 and r=n=2. Thus, this wavelength-specific multi-directional launch architecture is able to achieve a full 30° x 30° FOV because the respective barrel-shaped boxes corresponding to the red FOV 1430, green FOV 1432, and blue FOV 1434 corresponding to TIR light are completely located within the annular region.

[0208] refer to Fig. 14C , the orientations of the gratings in the red ICG 1410 and the green ICG 1412 and the red ICG 1411 and the green ICG 1413 are oriented so that the red light and the green light are emitted into the eyepiece waveguide toward the region 1442 of the CPE 1440 on the world side and the region 1452 of the CPE 1450 on the user side. The orientations of the gratings in the blue ICG 1414 and the blue ICG 1415 are oriented so that the blue light is emitted into the eyepiece waveguide toward the region 1444 of the CPE 1440 on the world side and the region 1454 of the CPE 1450 on the user side. Regions 1444 and 1454 have gratings corresponding to the grating vector k1. Region 1442 having a grating corresponding to the grating vector k3 is disposed adjacent to region 1444. Regions 1444 and 1454 having a grating corresponding to the grating vector k4 are disposed adjacent to region 1444. 2a and K 2b Region 1452 of the two-dimensional grating is disposed adjacent to region 1454 .

[0209] refer to Fig. 14B and 14D , the red light and green light emitted toward region 1442 of CPE 1440 are incident on the grating corresponding to grating vector k3, and the red light and green light emitted toward region 1452 of CPE 1450 are incident on the grating corresponding to grating vector k3 in the first direction. 2a and the grating vector k in the second orthogonal direction 2b The two-dimensional grating represented by . Corresponding to the grating vectors k3, k 2a and k 2b The diffraction of leads to diffraction in the plane of the eyepiece waveguide. As a result, the response is related to the grating vector k 2a Corresponding to the diffraction, the red FOV 1430 is transferred to the red FOV 1431 in k-space, and the green FOV 1432 is transferred to the green FOV 1433 in k-space, and in response to the grating vector k 2bCorresponding to the diffraction, red FOV 1430 is transferred in k-space to red FOV 1437, and green FOV 1432 is transferred in k-space to green FOV 1439. Diffraction in region 1444 of CPE 1440 from the grating corresponding to grating vector k3 results in outcoupling from the eyepiece waveguide.

[0210] Blue light emitted toward region 1444 in CPE 1440 and region 1454 in CPE 1450 is incident on the gratings corresponding to grating vector k1 in regions 1444 and 1454, thereby diffracting in the plane of the eyepiece waveguide. As a result, blue FOV 1434 is transferred to blue FOV 1435 in k-space. 2a Diffraction of the grating in region 1444 of CPE 1440 results in outcoupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths are k L →k 2a / K 2b →k3, the diffraction path represents the minimum order of interaction with different grating types as the incident light travels from the projector to the user's eye. The diffraction path for blue wavelengths is k H →k1→k 2a .

[0211] Fig.15A is a simplified k-space diagram showing the field of view and ICG grating vectors of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention. Fig. 15B is a simplified k-space diagram showing the field of view and CPE grating vectors of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention. Fig. 15C is a simplified plan view of the world side of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission according to an embodiment of the present invention. Fig.15D yes Fig. 15C A simplified plan view of the user side of a first eyepiece waveguide including a two-dimensional grating with multi-directional emission is shown.

[0212] First reference Fig. 15C and 15D The first eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, wherein a separate ICG pupil (such as Fig. 15C 1510, green ICG 1512 and blue ICG 1514) and Fig.15DThe red ICG 1511, green ICG 1513, and blue ICG 1515 shown coupled to the user side of the eyepiece waveguide are used in combination. Thus, these six ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors for the various ICGs designed for green wavelengths are the same for blue light (and blue ICG) as for red and green light (and red and green ICGs). Although Fig.15D The illustrated embodiment includes red ICG 1511, green ICG 1513, and blue ICG 1515 coupled to the user side of the eyepiece waveguide, but this is not required and in some embodiments, red ICG 1511, green ICG 1513, and blue ICG 1515 are optional.

[0213] refer to Fig.15A , raster vector k H represents the diffraction at the first distance in k-space, and the grating vector k L represents diffraction at the second distance in k-space. Thus, for red ICG 1510 and green ICG 1512 coupled to the world side of the eyepiece waveguide, or red IGG 1511 and green ICG 1513 coupled to the user side of the eyepiece waveguide, light at the center of the FOV is diffracted into the eyepiece waveguide as indicated by the grating vector k L 1530 for red wavelengths and a green FOV 1532 for green wavelengths. Both FOVs are located within the annular region between r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using a blue ICG 1514 coupled to the world side of the eyepiece waveguide or a blue ICG 1515 coupled to the user side of the eyepiece waveguide is shown as k H 1534 for the blue wavelengths. This FOV is located within the annular region between r=n=1 and r=n=2. Thus, this wavelength-specific multi-directional launch architecture enables a full 30° x 30° FOV because the respective barrel-shaped boxes corresponding to the red FOV 1530, green FOV 1532, and blue FOV 1534 corresponding to TIR light are completely located within the annular region.

[0214] refer to Fig. 15C, the orientation of the gratings in red ICG 1510 and green ICG 1512 and red ICG 1511 and green ICG 1513 is oriented so that red light and green light are emitted into the eyepiece waveguide toward the upper left portion of CPE 1540 on the world side and the upper left portion of CPE 1550 on the user side. The orientation of the gratings in blue ICG 1514 and blue ICG 1515 is oriented so that blue light is emitted into the eyepiece waveguide toward the lower right portion of CPE 1540 on the world side and the lower right portion of CPE 1550 on the user side. CPE 1540 has gratings corresponding to grating vector k2 and grating vector k3 across the entire CPE. CPE 1550 has gratings corresponding to grating vector k1 and grating vector k2 across the entire CPE.

[0215] refer to Fig. 15B and 15D , red and green light emitted toward the upper left portion of CPE 1540 is incident on components of the two-dimensional grating corresponding to grating vector k2, and red and green light emitted toward the upper left portion of CPE 1550 is incident on components of the two-dimensional grating corresponding to grating vector k2. Diffraction corresponding to grating vector k2 results in diffraction within the eyepiece waveguide plane. As a result, in response to diffraction corresponding to grating vector k2, red FOV 1530 is transferred to red FOV 1531 in k-space, and green FOV 1532 is transferred to green FOV 1533 in k-space. Diffraction in CPE 1540 from the grating corresponding to grating vector k3 results in outcoupling from the eyepiece waveguide.

[0216] Blue light emitted toward the lower right portion of CPE 1550 is incident on the components of the two-dimensional grating corresponding to the grating vector k1 and is thereby diffracted in the plane of the eyepiece waveguide. As a result, blue FOV 1534 is shifted in k-space to blue FOV 1535. Diffraction in CPE 1540 and CPE 1550 from the components of the two-dimensional grating corresponding to the grating vector k2 results in outcoupling from the eyepiece waveguide. Therefore, the diffraction paths for the red and green wavelengths are k L →k2→k3, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. The diffraction path for blue wavelengths is k H →k1→k2.

[0217] As about Figure 3D As discussed, Fig. 15C and 15D The diffractive structures shown fabricated on the world side and the user side can be implemented on opposite sides or in a single-sided design. Fig. 15C and 15DThe gratings shown for grating vectors k1, k2, and k3 can be implemented as a single-sided design, where all gratings are coupled to a single side of the eyepiece waveguide. Fig. 15C and 15D The functions discussed can be achieved using a single-sided design.

[0218] Fig.16A is a simplified k-space diagram showing the field of view and ICG grating vectors of a wide field of view eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 16B is a simplified k-space diagram showing the field of view and CPE grating vectors of a wide field of view eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 16C is a simplified plan view of the world side of a wide field of view eyepiece waveguide with multi-directional emission in accordance with an embodiment of the present invention. Fig.16D yes Fig. 16C A simplified plan view of the user side of a wide field of view eyepiece waveguide with multi-directional emission is shown.

[0219] Figures 16A-16D The design shown corresponds to Figures 8A-8D The design shown is modified in that Fig.16A and Fig. 16B The field of view shown is wider horizontally than Fig. 8A and 8B Field of view shown.

[0220] First reference Fig. 16C and 16D The wide-field eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a separate ICG pupil (such as Fig. 16C ) and Fig.16D The red ICG 1611, green ICG 1613, and blue ICG 1615 shown coupled to the user side of the eyepiece waveguide are used in combination. Thus, these six ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors of the various ICGs designed for green wavelengths are different for blue light (and blue ICG) than for red and green light (and red and green ICGs). Although Fig.16D The illustrated embodiment includes red ICG 1611, green ICG 1613, and blue ICG 1615 coupled to the user side of the eyepiece waveguide, but this is not required and in some embodiments, red ICG 1611, green ICG 1613, and blue ICG 1615 are optional.

[0221] refer to Fig.16A , raster vector kH represents diffraction at larger distances (height) in k-space, and the grating vector k L represents the diffraction at smaller distances (low) in k-space. Therefore, corresponding to the grating vector k L The gratings of are characterized by the same grating size (ie, the same grating periodicity, e.g., 525 nm / ~1.5≈350 nm), and correspond to the grating vector k H The gratings of the eyepiece waveguide are characterized by a larger grating size (i.e., a smaller grating periodicity, such as 525 nm / ~1.9≈276 nm). Therefore, for the red ICG 1610 and green ICG 1612 coupled to the world side of the eyepiece waveguide, or the red IGG 1611 and green ICG 1613 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide, as indicated by the grating vector k L 1630 for red wavelengths and a green FOV 1632 for green wavelengths. Both FOVs (although their horizontal widths are greater) are located within the annular region between r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using either the blue ICG 1614 coupled to the world side of the eyepiece waveguide or the blue ICG 1615 coupled to the user side of the eyepiece waveguide is shown as k H 1634 for the blue wavelengths. This FOV (although its horizontal width is larger) is located within the annular region between r=n=1 and r=n=2. Thus, this wavelength-specific multi-directional launch architecture is able to achieve a full 40° x 30° FOV, as the respective wide fields of view corresponding to the red FOV 1630, green FOV 1632, and blue FOV 1634 corresponding to TIR light are located entirely within the annular region.

[0222] refer to Fig. 16C , the orientation of the gratings in the red ICG 1610 and the green ICG 1612 and the red ICG 1611 and the green ICG 1613 is oriented so that the red light and the green light are emitted into the eyepiece waveguide toward the area 1642 of the CPE 1640 on the world side and the area 1652 of the CPE 1650 on the user side. The orientation of the gratings in the blue ICG 1611 and the blue ICG 1620 is oriented so that the blue light is emitted into the eyepiece waveguide toward the area 1644 of the CPE 1640 on the world side and the area 1654 of the CPE 1650 on the user side.

[0223] refer to Fig. 16B and 16D, red and green light emitted toward region 1652 of CPE 1650 is incident on the grating corresponding to grating vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, red FOV 1630 is transferred to red FOV 1631 in k-space, and green FOV 1632 is transferred to green FOV 1633 in k-space. Diffraction in region 1642 from the grating corresponding to grating vector k3 causes outcoupling from the eyepiece waveguide. Blue light emitted toward region 1644 in CPE 1640 and region 1654 in CPE 1650 is incident on the grating corresponding to grating vector k1 in regions 1644 and 1654, thereby diffracting in the plane of the eyepiece waveguide. As a result, blue FOV 1634 is transferred to blue FOV 1635 in k-space. Diffraction in region 1652 from the grating corresponding to grating vector k2 results in outcoupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths are k L →k2→k3, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. The diffraction path for blue wavelengths is k H →k1→k2.

[0224] like Fig.16A and 16B As shown, the red FOV 1630 / 1631, the green FOV 1632 / 1633, and the blue FOV 1634 / 1635 (although of greater horizontal width) are all located within the annular region between r = n = 1 and r = n = 2. Therefore, propagation in the plane of the eyepiece waveguide as well as outcoupling is performed without cropping the FOV.

[0225] The inventors have determined that the multi-directional emission waveguide design discussed herein is particularly useful for AR display designs where the projector is located near the upper right corner of the eyepiece. The geometric arrangement of different grating regions, gradient zones, grating parameters, materials, ICG, and projector position, etc. can vary according to embodiments of the present invention and are parameters that affect the display performance of the eyepiece. These parameters can be adjusted to achieve the uniformity and efficiency required for AR display.

[0226] Note that Figure 7C In the embodiments shown in FIG. 14A , FIG. 14B , FIG. 14C , FIG. 14D , and FIG. 14C , a multi-directional emission waveguide design is shown that uses a single ICG pupil to emit all three primary colors (i.e., red, green, and blue wavelengths of light) into the eyepiece waveguide. Several designs that can be used to achieve this multi-directional emission are described below.

[0227] Fig.17A is a simplified cross-sectional diagram showing an eyepiece waveguide with a double-sided ICG according to an embodiment of the present invention. Fig.17A, the eyepiece waveguide 1700 receives incident light from a projector (not shown). A first ICG 1710 operating in a transmission mode is coupled to a first side 1701 of the eyepiece waveguide 1700. A second ICG 1712 operating in a reflection mode is coupled to a second side 1702 of the eyepiece waveguide 1700. Light diffracted from the first ICG 1710 and the second ICG 1712 propagates in the eyepiece waveguide 1700 toward the CPE 1720, which diffracts the light within the plane of the eyepiece waveguide and couples the light out of the eyepiece waveguide toward the user.

[0228] Fig. 17B It is shown Fig.17A The exploded plan view of the bilateral ICG is shown in Figure 1. Fig.17A As shown, incident light is diffracted by ICG 1710 operating in transmission mode. As discussed above, the grating of ICG 1710 is represented by the grating vector k L The incident light passing through the eyepiece waveguide 1700 is diffracted by the ICG 1712 operating in the reflection mode. As discussed above, the grating of the ICG 1712 is defined by the grating vector k H Definition. Thus, in this embodiment, a combined two-dimensional diffraction structure is realized using one-dimensional ICG gratings coupled to both sides of the eyepiece, each grating having a different grating vector (ie, grating periodicity).

[0229] Fig. 17C is a simplified cross-sectional view showing a metallized blazed grating according to an embodiment of the present invention. Fig.17D is a simplified cross-sectional view showing a coated blazed grating according to an embodiment of the present invention. Fig.17E is a simplified cross-sectional view showing a coated tilted grating according to an embodiment of the present invention. Fig.17F is a simplified cross-sectional view showing a coated blazed grating according to an embodiment of the present invention.

[0230] like Figures 17B-17F As shown, the 1D ICG can have different coatings deposited on top of the grating structure and can have different shapes, including tilted and blazed type gratings and one or more coatings as appropriate. In addition, metastructures including holes / posts, multi-order structures, and discontinuous structures can be used. ICGs that operate in reflection mode can be covered with highly reflective metals, such as aluminum or silver, which improve the overall efficiency of light injection into the eyepiece waveguide. Therefore, embodiments of the present invention may utilize gratings including tilted, sawtooth and / or multi-order structures, etc., in order to improve directionality toward the user. In addition, the gratings discussed herein can be biased with an outer coating (e.g., TiO2) that is formed over the grating structure in the ICG or CPE.

[0231] In addition to imprinting diffractive structures into polymer resins (whose refractive index ranges, for example, from 1.5 to 2.0) as described more fully below, embodiments of the present invention may also utilize diffractive structures etched into high refractive index materials, including Si3N4, ZrO2, TiO2, LiNbO3, LiTaO3, SiC, etc., which may be deposited as a thin film on a substrate, which may be referred to as a support structure, or may be used as an eyepiece waveguide substrate. The diffractive structures may be etched using dry etching processes, such as reactive ion etching (RIE), inductively coupled plasma-reactive ion etching (ICP-RIE), ion beam etching (IBE), etc., and dry etching may utilize various gases, including CF4, C2F8, CHF3, SF6, O2, Ar, He, BCl3, Cl2, etc. The diffractive structure can also be formed in one or more overcoat films (e.g., MgF2, SiO2, Si3N4, ZrO2, TiO2, SiC, etc., whose refractive index can be in the range of 1.3 to 2.6) deposited on top of an imprinted polymer (e.g., a polymer resin with a refractive index of 1.5 to 2.0 and an imprinted diffraction pattern). In addition to imprinting and etching, diffraction patterns can also be formed by molding substrates (e.g., polymers with a refractive index of 1.5 to 1.75). These molded substrates can then be overcoated with a high refractive index film. These designs can improve the diffraction efficiency of TIR light, reduce external light reflections, or both.

[0232] With regard to embossing the diffraction structure into the polymer resin, the embossable prepolymer material may include a resin material such as epoxy vinyl ester. The resin may include a vinyl monomer (e.g., methyl methacrylate) and / or a difunctional or trifunctional vinyl monomer (e.g., diacrylate, triacrylate, dimethacrylate, etc.), with or without aromatic molecules in the monomer. The prepolymer material may include a monomer having one or more functional groups (such as alkyl, carboxyl, carbonyl, hydroxyl and / or alkoxy). Sulfur atoms and aromatic groups both have a high polarizability and can be introduced into these acrylate components to increase the refractive index of the formulation, and generally provide a refractive index in the range of 1.5 to 1.75. In some implementations, the prepolymer material may include a cyclic aliphatic epoxy resin containing a resin that can be cured using ultraviolet light and / or heat. In addition, the prepolymer material may include an ultraviolet cationic photoinitiator and a co-reactant to promote effective ultraviolet curing under ambient conditions.

[0233] Introducing inorganic nanoparticles (NPs) such as ZrO2 and TiO2 into such imprintable resin polymers can significantly increase the refractive index, for example, up to n = 2.1. In addition, the use of pure ZrO2 and TiO2 crystals can produce refractive indices of n = 2.2 and n = 2.4-2.6 at 532nm, respectively. For the preparation of optical nanocomposites of acrylate monomers and inorganic nanoparticles, the particle size is usually less than 10nm to avoid excessive Rayleigh scattering. Due to their high specific surface area, high polarity and incompatibility with the cross-linked polymer matrix, ZrO2 NPs have a tendency to aggregate in the polymer matrix. Surface modification of NPs can be used to overcome this problem. In this technique, the hydrophilic surface of ZrO2 is modified to be compatible with organic matter, thereby enabling the NPs to be uniformly mixed with the polymer. This modification can be performed with a capping agent containing silane and carboxylic acid. One end of the capping agent is bound to the ZrO2 surface, while the other end of the capping agent contains a functional group or a non-functional organic part that can participate in acrylate crosslinking. An example of surface modified sub-10nm ZrO2 particles is Pixelligent Technologies TM and Cerion Advanced Materials TM These functionalized nanoparticles are typically sold as homogenous mixtures uniformly suspended in a solvent that can be combined with other substrates to give a resist formulation with jettable viscosity and increased refractive index.

[0234] By contacting the prepolymer with a template (e.g., in the case of imprint lithography, such as J-FIL TM , wherein the prepolymer material is dispensed using an inkjet), and the prepolymer is exposed to a wavelength between 310 nm and 410 nm and an intensity of 0.1 J / cm 2 Up to 100J / cm 2 The method may further include applying heat while exposing the prepolymer to actinic radiation such that the temperature of the prepolymer is between 40°C and 120°C.

[0235] Figures 18A-18D A two-dimensional ICG coupled to a single side of the eyepiece waveguide is shown. Each of these two-dimensional ICGs has a grating vector that diffracts light in two dimensions to achieve a multi-directional emission design.

[0236] Fig.18A is a perspective view of a two-dimensional ICG according to an embodiment of the present invention. Fig.18A In FIG. 1 , a multi-row blazed grating structure is shown. In the column direction, each row also blazes, as shown by the height variation of each row in the column direction. Thus, a two-dimensional grating structure suitable for the embodiments described herein is provided.

[0237] Fig.18B is a perspective view of a two-dimensional ICG according to another embodiment of the present invention. Fig.18B In the embodiment shown, the columns arranged in rows and columns are shown. In the embodiment shown, one or more sides of the columns are inclined, but this is not required.

[0238] Fig.18C is a perspective view of a two-dimensional ICG according to a third embodiment of the present invention. Fig.18C In the embodiment shown, pyramidal elements arranged in rows and columns are shown. In the embodiment shown, the pyramidal elements are connected at the bottom of each element, but this is not necessary. In other embodiments, the pyramidal elements are separated from each other by a gap.

[0239] Fig.18D is a perspective view of a two-dimensional ICG according to a fourth embodiment of the present invention. Fig.18D In the embodiment shown, the columns are arranged in rows and columns. In the embodiment shown, the columns are in a stepped structure with a base and protrusions extending from the base. Although Fig.18D The step structure shown utilizes two steps, namely the base and the protrusion, but the embodiments of the present invention are not limited to such a two-step structure, and step structures with additional steps are also included within the scope of the embodiments described herein. In addition, although in this embodiment, the sides of the structure are parallel to each other, the sides can also be inclined as appropriate for a particular application. Those of ordinary skill in the art will recognize many variations, modifications, and alternatives.

[0240] The multi-directional emission design discussed herein emits blue light in a direction different from the direction in which red and green light are emitted. Other embodiments may emit blue and green light in the same direction and emit red light in a separate, different direction. Although not shown herein, these other embodiments are also included within the scope of the present invention.

[0241] For multi-directional emission designs where red and green light are emitted in the same direction, the same ICG design (e.g., pitch and grating orientation) can be used. Thus, although many of the multi-directional emission designs discussed herein utilize three separate ICGs for red, green, and blue light, the same ICG can also be used for red and green light. Figures 19A-19C Such an implementation is shown in .

[0242] Fig.19A is a simplified k-space diagram showing the field of view and ICG grating vectors of a third eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.19B is a simplified plan view of the world side of a third eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig.19C yes Fig.19B A simplified plan view of the user side of the third eyepiece waveguide with multi-directional emission is shown.

[0243] First reference Fig.19B and 19C The eyepiece waveguide adopts a multi-directional emission eyepiece waveguide design, in which a separate ICG pupil (such as Fig.19B The red / green ICG 1910 and blue ICG 1914 are shown in FIG. Fig.19C The red / green ICG 1911 and blue ICG 1915 shown coupled to the user side of the eyepiece waveguide are used in combination. Thus, these four ICGs are used to couple light from the projector into the eyepiece waveguide. However, as discussed more fully below, the grating periodicity and corresponding grating vectors for the various ICGs designed for green wavelengths are the same for blue light (and the blue ICG) as for red and green light (and the red / green ICGs). Although Fig.19C The illustrated embodiment includes red / green ICG 1911 and blue ICG 1915 coupled to the user side of the eyepiece waveguide, but this is not required and in some embodiments, red / green ICG 1911 and blue ICG 1915 are optional.

[0244] refer to Fig.19A , raster vector k H represents the diffraction at the first distance in k-space, and the grating vector k L represents diffraction at the second distance in k-space. Thus, for red / green ICG 1910 coupled to the world side of the eyepiece waveguide, or red / green ICG 1911 coupled to the user side of the eyepiece waveguide, light at the center of the FOV is diffracted into the eyepiece waveguide as indicated by the grating vector k L 1930 for red wavelengths and a green FOV 1932 for green wavelengths. Both FOVs are located within the annular region between r=n=1 and r=n=2. Light diffracted into the eyepiece waveguide using a blue ICG 1914 coupled to the world side of the eyepiece waveguide or a blue ICG 1915 coupled to the user side of the eyepiece waveguide is shown as k H 1930, green FOV 1932, and blue FOV 1934, which correspond to TIR light, are completely within the annular region.

[0245] refer to Fig.19B, the orientation of the gratings in the red / green ICG 1910 and the red / green ICG 1911 is oriented so that the red light and the green light are emitted into the eyepiece waveguide toward the region 1942 of the CPE 1940 on the world side and the region 1952 of the CPE 1950 on the user side. The orientation of the gratings in the blue ICG 1914 and the blue ICG 1915 is oriented so that the blue light is emitted into the eyepiece waveguide toward the region 1944 of the CPE 1940 on the world side and the region 1954 of the CPE 1950 on the user side. Regions 1944 and 1954 have gratings corresponding to the grating vector k1. Region 1942 having a grating corresponding to the grating vector k3 is disposed adjacent to region 1944. Region 1952 having a grating corresponding to the grating vector k2 is disposed adjacent to region 1954.

[0246] refer to Fig.19A and 19C , red and green light emitted toward region 1952 of CPE 1950 is incident on the grating corresponding to grating vector k2, which causes diffraction in the plane of the eyepiece waveguide. Diffraction in region 1942 of CPE 1940 from the grating corresponding to grating vector k3 causes outcoupling from the eyepiece waveguide.

[0247] Blue light emitted toward region 1944 in CPE 1940 and region 1954 in CPE 1950 is incident on the gratings corresponding to grating vector k1 in regions 1944 and 1954 and is diffracted in the plane of the eyepiece waveguide. Diffraction in region 1952 of CPE 1950 from the grating corresponding to grating vector k2 results in outcoupling from the eyepiece waveguide. The diffraction paths for the red and green wavelengths are therefore k L →k2→k3, this diffraction path represents the minimum order of interaction with different grating types when the incident light propagates from the projector to the user's eye. The diffraction path for blue wavelengths is k H →k1→k2.

[0248] Therefore, in Figures 19A-19C In the illustrated embodiment, two ICGs are utilized that are coupled to the world side and / or the user side. This embodiment, along with other advantages, can reduce the overall projector volume, which is an important consideration in the design of AR headsets.

[0249] Table 2 lists the approximate maximum (i.e., rounded) values ​​of possible fields of view for different material options according to embodiments of the present invention. In Table 2, the materials are listed in the first column in order of increasing refractive index values ​​for one of the unidirectional emission and multi-directional emission architectures. The second column represents the best case scenario for the unidirectional emission architecture, where the projector is horizontally aligned with the center of the CPE (i.e., the nominal eye position). The third and fourth columns represent scenarios where the projector is located at the 2 o'clock and 1 o'clock directions relative to the center of the CPE, respectively. As shown in Table 2, for a given material option, the multi-directional emission architecture discussed herein provides a larger field of view than that possible with a unidirectional emission architecture.

[0250]

[0251]

[0252] Table 2

[0253] Fig. 20A is a simplified k-space diagram showing the field of view and ICG grating vectors of the eyepiece waveguide according to an embodiment of the present invention. Fig. 20A , the grating vector 2010 is shown in conjunction with a projector aligned horizontally with the center of the CPE so that light is injected from the 3 o'clock position. The data in the second column of Table 2 corresponds to this k-space map.

[0254] Fig. 20B is a simplified k-space diagram showing the field of view and ICG grating vectors of another eyepiece waveguide according to an embodiment of the present invention. Fig. 20B , the grating vector 2020 is shown in conjunction with the projector located at 2 o'clock relative to the center of the CPE. The data in the third column of Table 2 corresponds to this k-space map.

[0255] Fig. 20C is a simplified k-space diagram showing the field of view and ICG grating vectors of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention. Fig. 20C , grating vectors 2030 and 2032 correspond to injection of red and green light, respectively, from the 3 o'clock position relative to the center of the CPE. Grating vector 2034 is shown in conjunction with injection of blue light, where the projector is located at 1 o'clock relative to the center of the CPE. The data in the fourth column of Table 2 corresponds to this k-space map.

[0256] These k-space plots and Table 2 show the maximum field of view possible for increasing waveguide substrate refractive index values ​​using different material options.For these k-space plots and Table 2, the central illumination wavelengths are 455nm (blue), 525nm (green), and 628nm (red).

[0257] The inventors have determined that the materials used for the waveguides are relatively lossy or absorptive at shorter wavelengths (i.e., blue wavelengths) compared to red and green wavelengths. This presents an efficiency issue for blue light, as light that is expected to propagate over a large area of ​​the eyepiece waveguide may be absorbed before being emitted or coupled out toward the user. Not only is the efficiency of blue light reduced due to this higher absorption, but, in addition, the nasal portion of the eyepiece (i.e., the portion farthest from the ICG / projector) may emit a reduced amount of blue light. This may present challenges in achieving good color uniformity for AR displays at all angles of incidence, as well as for people with small interpupillary distance (IPD).

[0258] Therefore, in the context of a multi-directional emission architecture, a choice can be made between different designs based on the total path length of the blue light as it diffuses and couples out of the eyepiece. Fig.21A Two different multi-directional transmission architectures shown in Figures 21B and 21C / 21D illustrate this process.

[0259] Fig.21A is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention, wherein blue light is emitted in a first direction. Fig. 21B yes Fig.21A Simplified plan view of the user side of the eyepiece waveguide with multi-directional emission, where blue light is emitted in a first direction. Fig.21A and 21B , blue light is emitted from blue ICG 2114 and blue ICG 2115 in the 7 o'clock direction, incident on region 2144 of CPE 2140 coupled to the world side and region 2154 of CPE 2150 coupled to the user side. The total path length from ICG 2114 and ICG 2115 to the center of CPE 2140 and CPE 2150, respectively, is shown by arrows 2103 and 2105, indicating how far (approximately) the blue light travels within the eyepiece waveguide before being coupled out in region 2142 of CPE 2140 and region 2152 of CPE 2150.

[0260] Fig. 21C is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to an embodiment of the present invention, wherein blue light is emitted in the second direction. Fig.21D yes Fig. 21C Simplified plan view of the user side of the eyepiece waveguide with multi-directional emission, where blue light is emitted in the second direction. Fig. 21C and 21D, blue light is emitted from blue ICG 2160 and blue ICG 2161 along the 10 o'clock direction, incident on region 2142 of CPE 2140 and region 2152 of CPE 2150. The total path length from ICG 2160 and ICG 2161 to the center of CPE 2140 and CPE 2150, respectively, is shown by arrows 2107 and 2109, indicating how far (approximately) the blue light travels within the eyepiece waveguide before being coupled out in region 2142 of CPE 2140 and region 2152 of CPE 2150. Based on Fig.21A Comparison of the path lengths shown in / 21B and 21C / 21D, Fig. 21C The design shown in / 21D outperforms the Fig.21A / 21B. This result has been verified by simulation based on full ray tracing.

[0261] The inventors have determined that the blue light absorption problem becomes more severe for materials (particularly glass) with higher refractive index (e.g., n>2.0), including the materials listed in Table 2. Therefore, for the selection of such high refractive index materials, the multi-directional emission design provides the freedom of choice to optimize the design with consideration for higher blue light efficiency. However, this choice is usually at the expense of reducing the maximum field of view value that can be achieved with the multi-directional emission design.

[0262] Fig.22A is a simplified k-space diagram showing the field of view, ICG grating vector, OPE grating vector and CPE grating vector of an eyepiece waveguide with multi-directional emission according to another embodiment of the present invention. Fig. 22B is a simplified plan view of the world side of an eyepiece waveguide with multi-directional emission according to another embodiment of the present invention.

[0263] Fig. 22B The architecture shown is different from the other architectures discussed in this article. Red light incident on the red ICG 2210 is launched into the eyepiece waveguide in a region closer to the center of the ring and then interacts with the orthogonal pupil expander (OPE-Red), which redirects the red light to the k-space location that red light would normally occupy. The red light is then coupled out of the CPE along with the green and blue light. This architecture provides a red bounce density comparable to the green and blue bounce densities.

[0264] refer to Fig.22A , raster vector k ICG-red represents diffraction by the red ICG 2210 at a first distance and direction in k-space, and the grating vector k ICG-green-blue= represents diffraction by the green / blue ICG 2212 at a second distance and direction in k-space. In this embodiment, the first distance and the second distance are different, and the first direction and the second direction are also different. Therefore, the red ICG 2210 and the green / blue ICG 2212 will couple in light (corresponding to the grating vector k ICG-red and raster vector k ICG-green-blue ) to produce a red FOV 2220, a green FOV 2222, and a blue FOV 2224, respectively. Region 2242 of CPE 2240 has a grating corresponding to the grating vector OPE-red, which transfers the red FOV 2220 in k-space to the red FOV 2231. Diffraction in region 2244 of CPE 2240 transfers the green FOV 2222 and the blue FOV 2224 in k-space to the green FOV 2233 and the blue FOV 2235 in k-space, to the blue FOV 2235. The diffraction (corresponding to the blue FOV 2235) coupled to the CPE (not shown) on the opposite side of the eyepiece waveguide Fig. 22B The grating vector CPE-k2) shown results in outcoupling from the eyepiece waveguide.

[0265] Thus, the emitted red light interacts with the grating in region 2242 corresponding to the grating vector OPE-red and is diffracted toward the center of CPE 2240 and then coupled out from there. Other implementations of this design are included within the scope of the present invention and are similar to other architectures discussed herein, Fig. 22B The illustrated embodiment provides an extension of the horizontal FOV beyond that achievable using a design based on unidirectional transmission.

[0266] Fig.23 1 shows image overlap in k-space and corresponding eyepiece designs according to various embodiments of the present invention. Fig.23 , schematic diagrams 2310, 2320, and 2330 show how, for various embodiments, an image overlaps a portion of a corresponding k-space. For ease of illustration, only a portion of the annular region between r=n=1 and r=n=2 is shown.

[0267] ICG 2312 is shown as being associated with FOV 2314 corresponding to schematic diagram 2310. The physical location of the projector of the AR wearable device affects the location of the ICG and the form factor of the AR wearable device. Therefore, the placement of the ICG relative to the user's eyes is shown by the line extending across FOV 2314 aligned with the ICG. Therefore, embodiments of the present invention enable different designs, including designs in which the projector / IGC is located near the temple or near the nose. In particular, the multi-directional emission (i.e., ICG functionality) capability discussed herein, combined with the multi-combiner (CPE, EPE, OPE) elements discussed herein, can be used to combine and couple out light with an increased FOV in various projector orientations for the user's AR virtual image.

[0268] like Fig.23 As shown, the ICG can be placed above the user's eye, as shown in ICG 2312, which corresponds to the situation where the image exists in the center and lower part of the k-space ring; placed above and to the side of the user's eye, as shown in ICG 2322, which corresponds to the situation where the image exists in the lower left part of the k-space ring; placed above and to the side of the user's eye, as shown in ICG 2324, which corresponds to the situation where the image exists in the lower left part of the k-space ring; or placed on the side of the user's eye, as shown in ICG2332, which corresponds to the situation where the image exists in the left part of the k-space ring. Therefore, the shape of the wearable device can vary according to the different shapes of the eyepiece waveguide discussed in this article. Those of ordinary skill in the art will recognize many variations, modifications, and alternatives.

[0269] Fig.24A perspective view of a wearable device 2400 according to an embodiment of the present invention is shown. The wearable device 2400 includes a frame 2402, which is configured to support one or more projectors 2404 at various locations along the inward-facing surface of the frame 2402, as shown. In some embodiments, the projector 2404 can be attached to a position close to the temple 2406. As an alternative or in addition, another projector can be placed at position 2408. For example, such a projector can include one or more liquid crystal on silicon (LCoS) modules, micro-LED displays, or fiber scanning devices, or be used in combination with them. In some embodiments, light from the projector 2404 or a projector set at position 2408 can be directed into the eyepiece waveguide 2410 for display to the user's eye. The projector placed at position 2412 can be slightly smaller because this brings the projector very close to the waveguide system. When the waveguide system guides light from the projector to the eyepiece waveguide 2410, the closer proximity can reduce the amount of light lost. In some embodiments, the projector at position 2412 may be used in conjunction with projector 2404 or a projector disposed at position 2408. Although not shown, in some embodiments, the projector may also be located at a position below the eyepiece waveguide 2410. Wearable device 2400 is also depicted as including sensors 2414 and 2416. Sensors 2414 and 2416 may take the form of forward and side-pointing optical sensors configured to characterize the real-world environment surrounding wearable device 2400.

[0270] It should also be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes thereto will be suggested to those skilled in the art and that these modifications and changes will be included within the spirit and scope of the present application and the scope of the appended claims.

Claims

1. An AR head-mounted device, comprising: projectile; An eyepiece waveguide supporting multi-directional emission, the eyepiece waveguide having a world side and a user side, and comprising: a first set of one or more in-coupling diffractive optical elements coupled to the world side of the eyepiece waveguide; wherein: a first subset of the first set of one or more in-coupled diffractive optical elements operable to diffract first light into the eyepiece waveguide, wherein the diffracted first light is characterized by a first angular range; and a second subset of the first set of one or more in-coupled diffractive optical elements operable to diffract second light into the eyepiece waveguide, wherein the diffracted second light is characterized by a second angular range different from the first angular range; and a second set of one or more in-coupling diffractive optical elements coupled to the user side of the eyepiece waveguide, wherein: a third subset of the second set of one or more in-coupled diffractive optical elements operable to diffract light within the first angular range; and Combined pupil expander.

2. The AR head mounted device according to claim 1, wherein: A fourth subset of the second set of one or more in-coupled diffractive optical elements is operable to diffract light within the second angular range.

3. The AR head mounted device according to claim 1, wherein: The AR headset includes a single waveguide.

4. The AR head mounted device according to claim 1, wherein: The eyepiece waveguide supports propagation of multiple wavelengths of light.

5. The AR head mounted device according to claim 1, wherein: The combined pupil expander is operable to diffuse light laterally in the eyepiece waveguide and couple light out through the user side of the eyepiece waveguide.

6. The AR head mounted device according to claim 1, wherein: At least one of the first set of one or more in-coupling diffractive optical elements or the second set of one or more in-coupling diffractive optical elements overlaps.

7. An eyepiece waveguide for augmented reality applications, the eyepiece waveguide comprising: substrate; A set of in-coupling diffractive optical elements coupled to the substrate, wherein: a first subset of the set of in-coupled diffractive optical elements operable to diffract light into the substrate along a first range of propagation angles; and a second subset of the set of in-coupled diffractive optical elements operable to diffract light into the substrate along a second range of propagation angles; and A combined pupil expander diffractive optical element is coupled to the substrate.

8. The eyepiece waveguide of claim 7, wherein: The first subset of the set of coupled-in diffractive optical elements is characterized by a first grating periodicity and the second subset of the set of coupled-in diffractive optical elements is characterized by a second grating periodicity that is greater than the first grating periodicity.

9. The eyepiece waveguide of claim 7, wherein: The combined pupil expander diffractive optical element includes a first region characterized by a first grating orientation and a second region characterized by a second grating orientation different from the first grating orientation.

10. The eyepiece waveguide according to claim 7, wherein: The eyepiece waveguide further comprises: A second set of in-coupling diffractive optical elements is coupled to the substrate, wherein a first subset of the second set of in-coupling diffractive optical elements is operable to diffract light into the substrate along the first range of propagation angles.

11. The eyepiece waveguide of claim 10, wherein: The set of in-coupling diffractive optical elements is coupled to the substrate on a world-side surface; and The second set of in-coupling diffractive optical elements is coupled to the substrate on a user-side surface opposite the world-side surface.

12. The eyepiece waveguide of claim 7, wherein: The eyepiece waveguide also includes a second combined pupil expander diffractive optical element coupled to the substrate.

13. The eyepiece waveguide of claim 12, wherein: the combined pupil expander diffractive optical element is coupled to the substrate on a world side surface; and The second combined pupil expander diffractive optical element is coupled to the substrate on a user-side surface opposite the world-side surface.

14. The eyepiece waveguide of claim 7, wherein: The eyepiece waveguide is optically coupled to a projector, which is operable to output a red wavelength, a green wavelength, and a blue wavelength, wherein the eyepiece waveguide is operable to support light propagation of the red wavelength, the green wavelength, and the blue wavelength.

15. The eyepiece waveguide of claim 7, wherein: The refractive index of the substrate is between 1.8 and 2.

3.

16. The eyepiece waveguide of claim 7, wherein: The substrate includes silicon carbide having a refractive index of 2.

7.

17. The eyepiece waveguide of claim 7, wherein: The substrate includes a polymer resin having a refractive index between 1.3 and 2.

6.

18. The eyepiece waveguide of claim 7, wherein: The substrate has a refractive index between 1.8 and 2.7, and the set of in-coupled diffractive optical elements comprises structures etched into the substrate.

19. The eyepiece waveguide of claim 7, wherein: The substrate comprises a support structure and a layer having a refractive index between 1.8 and 2.7 coupled to the support structure, wherein the set of in-coupled diffractive optical elements comprises structures etched into the layer.

20. The eyepiece waveguide of claim 7, wherein: The set of in-coupled diffractive optical elements comprises structures etched into the substrate.

21. The eyepiece waveguide of claim 20, further comprising a layer having a refractive index between 1.8 and 2.7 coupled to the substrate.

22. An eyepiece waveguide for augmented reality applications, the eyepiece waveguide comprising: substrate; A set of in-coupling diffractive optical elements coupled to the substrate, wherein the set of in-coupling diffractive optical elements comprises: a first in-coupling diffractive optical element and a second in-coupling diffractive optical element operable to diffract light into the substrate along a first range of propagation angles; and a third in-coupling diffractive optical element operable to diffract light into the substrate along a second range of propagation angles; and a combined pupil expander diffractive optical element coupled to the substrate, wherein the combined pupil expander diffractive optical element comprises: a first portion that faces the world-side surface and includes a first region characterized by a first raster vector and a second region characterized by a second raster vector; and The second portion faces the user-side surface and includes a third area characterized by the first grating vector and a fourth area characterized by a third grating vector.

23. The eyepiece waveguide of claim 22, wherein: The first coupling-in diffractive optical element and the second coupling-in diffractive optical element are characterized by a first grating periodicity, and the third coupling-in diffractive optical element is characterized by a second grating periodicity that is smaller than the first grating periodicity.

24. The eyepiece waveguide of claim 22, wherein: The first region is characterized by a first grating orientation and the second region is characterized by the first grating orientation.

25. The eyepiece waveguide of claim 22, wherein: The third region is characterized by a first grating orientation and the second region is characterized by a second grating orientation different from the first grating orientation.

26. The eyepiece waveguide of claim 22, wherein: The set of in-coupling diffractive optical elements further comprises: a fourth in-coupling diffractive optical element and a fifth in-coupling diffractive optical element operable to diffract light into the substrate along the first propagation angle range; and A sixth in-coupling diffractive optical element is operable to diffract light into the substrate along the second propagation angle range.

27. The eyepiece waveguide of claim 26, wherein: The first in-coupling diffractive optical element, the second in-coupling diffractive optical element, and the third in-coupling diffractive optical element are coupled to the substrate on a world-side surface; and The fourth in-coupling diffractive optical element, the fifth in-coupling diffractive optical element and the sixth in-coupling diffractive optical element are coupled to the substrate on a user-side surface opposite to the world-side surface.

28. The eyepiece waveguide of claim 26, wherein: The fourth in-coupling diffractive optical element and the fifth in-coupling diffractive optical element are characterized by a first grating periodicity, and the sixth in-coupling diffractive optical element is characterized by a second grating periodicity that is smaller than the first grating periodicity.

29. The eyepiece waveguide of claim 22, wherein: The eyepiece waveguide is optically coupled to a projector, which is operable to output a red wavelength, a green wavelength, and a blue wavelength, wherein the eyepiece waveguide is operable to support light propagation of the red wavelength, the green wavelength, and the blue wavelength.

30. The eyepiece waveguide of claim 22, wherein: The first area is located on the world-side surface, opposite to the third area located on the user-side surface.

31. The eyepiece waveguide of claim 22, wherein: The second area is located on the world-side surface, opposite to a fourth area located on the user-side surface.

32. The eyepiece waveguide of claim 22, wherein: The first coupling-in diffractive optical element and the second coupling-in diffractive optical element are formed by a grating vector k L Characterization; The third coupling diffractive optical element is composed of a grating vector k H Characterization; The first region and the third region are characterized by a grating vector k1; The second region is characterized by a grating vector k3; and The fourth region is characterized by a grating vector k2.

33. The eyepiece waveguide of claim 32, wherein: The diffraction path of the red and green wavelengths is k L →k2→k3, and the diffraction path of the blue wavelength is k H →k1→k2.

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