Method and system for IP piece waveguide display using a multi-directional radiation structure

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 within 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 within the substrate along a second range of propagation angles. The eyepiece waveguide also includes a synthetic pupil expander diffractive optical element coupled to the substrate.

Description

Technical Field

[0001]

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 359,561, filed on July 8, 2022, entitled "MULTI - LAUNCH AND MULTI - COMBINER EP ARCHITECTURE", the disclosure of which is hereby incorporated by reference in its entirety for all purposes.

Background Art

[0002]

[0002] Modern computer and display technologies have facilitated the development of systems for so - called "virtual reality" (VR) or "augmented reality" (AR) experiences, where digitally reproduced images or portions thereof are presented to viewers in a manner that makes them appear or be perceived as if they were real. A scenario typically involves presenting digital or virtual image information without transparency to other actual real - world visual inputs, and an AR scenario typically involves presenting digital or virtual image information as an extension to the visualization of the real world around the viewer.

[0003]

[0003] Despite these advancements in display technologies, there is a need in the art for improved methods and systems related to augmented reality systems, particularly display systems.

Summary of the Invention

[0004]

[0004] Embodiments of the present invention generally relate to AR / MR products that use a single active - layer diffractive waveguide. For example, some embodiments maximize the augmented reality display field of view within an eyepiece based on a single - layer diffractive optical waveguide that uses multi - direction radiation, diffusion, and out - coupling.

[0005]

[0005] The field of view of AR displays using folded optical waveguides is largely determined by the refractive index of the waveguide material and the underlying grating structure in order to couple light in, diffuse it, and couple it out. Embodiments described herein utilize a unique structure based on the multi-directional emission of light into the waveguide, and the arrangement of a series of diffractive elements for diffusion and out-coupling enables a larger field of view than would be possible with a unidirectional in-coupling and emission structure.

[0006]

[0006] According to an embodiment of the present invention, an AR headset is provided. The AR headset includes a projector and an eyepiece waveguide that supports multi-directional emission. The eyepiece waveguide has a world side and a user side, and includes a first set of one or more in-coupling diffractive optical elements coupled to the world side of the eyepiece waveguide. A first subset of the first set of one or more in-coupling diffractive optical elements is operable to diffract a first light within the eyepiece waveguide, and the diffracted first light is characterized by a first angular range. A second subset of the first set of one or more in-coupling diffractive optical elements is operable to diffract a second light within the eyepiece waveguide, and the diffracted second light is characterized by a second angular range different from the first angular range. The eyepiece waveguide also includes a second set of one or more in-coupling diffractive optical elements coupled to the user side of the eyepiece waveguide. A third subset of the second set of one or more in-coupling diffractive optical elements is operable to diffract light within the first angular range. The AR headset also includes a synthetic pupil expander.

[0007]

[0007] A fourth subset of the second set of one or more in-coupling diffractive optical elements may be operable to diffract light within a second angular range. The AR headset may utilize a single waveguide. The eyepiece waveguide may support the propagation of light of multiple wavelengths. The synthetic pupil expander may be operable to laterally diffuse light within the eyepiece waveguide and out-couple light through the user side of the eyepiece waveguide. 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 may overlap.

[0008]

[0008] 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 range of a first propagation angle, and a second subset of the set of in-coupling diffractive optical elements is operable to diffract light into the substrate along a range of a second propagation angle. The eyepiece waveguide also includes a synthetic pupil expander diffractive optical element coupled to the substrate.

[0009] The first subset of the set of in-coupling diffractive optical elements can be characterized by a first grating period, and the second subset of the set of in-coupling diffractive optical elements can be characterized by a second grating period that is larger than the first grating period. The synthetic pupil expander diffractive optical element can include a first region characterized by a first grating direction and a second region characterized by a second grating direction different from the first grating direction. The eyepiece waveguide can further include a second set of in-coupling diffractive optical elements coupled to the substrate, and the first subset of the second set of in-coupling diffractive optical elements is operable to diffract light within the substrate along a range of first propagation angles. The set of in-coupling diffractive optical elements can be coupled to the substrate on the world side surface, and the second set of in-coupling diffractive optical elements can be coupled to the substrate on the user side surface facing the world side surface. The eyepiece waveguide can further include a second synthetic pupil expander diffractive optical element coupled to the substrate. The synthetic pupil expander diffractive optical element is coupled to the substrate on the world side surface, and the second synthetic pupil expander diffractive optical element is coupled to the substrate on the user side surface facing the world side surface. The eyepiece waveguide is optically coupled to a projector operable to output red, green, and blue wavelengths, and the eyepiece waveguide is operable to support light propagation at red, green, and blue wavelengths.

[0010] According to certain embodiments 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 can include a first in-coupling diffractive optical element and a second in-coupling diffractive optical element operable to diffract light within the substrate along a first range of propagation angles, and a third in-coupling diffractive optical element operable to diffract light within the substrate along a second range of propagation angles. The eyepiece waveguide also includes a synthetic pupil expander diffractive optical element coupled to the substrate. The synthetic pupil expander includes a first portion facing the world side surface and including a first region characterized by a first lattice vector and a second region characterized by a second lattice vector, and a second portion facing the user side surface and including a third region characterized by the first lattice vector and a fourth region characterized by a third lattice vector.

[0011]

[0011] The first in-coupling diffractive optical element and the second in-coupling diffractive optical element are characterized by a first grating period, and the third in-coupling diffractive optical element is characterized by a second grating period smaller than the first grating period. The first region is characterized by a first grating direction, and the second region is characterized by the first grating direction. The third region is characterized by the first grating direction, and the second region is characterized by a second grating direction different from the first grating direction. The set of in-coupling diffractive optical elements can further include a fourth in-coupling diffractive optical element and a fifth in-coupling diffractive optical element operable to diffract light into the substrate along a range of a first propagation angle, and a sixth in-coupling diffractive optical element operable to diffract light into the substrate along a range of a second propagation angle. The first in-coupling diffractive optical element, the second in-coupling diffractive optical element, and the third in-coupling diffractive optical element can be coupled to the substrate on the 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 can be coupled to the substrate on the user side surface facing the world side surface. The fourth in-coupling diffractive optical element and the fifth in-coupling diffractive optical element can be characterized by the first grating period, and the sixth in-coupling diffractive optical element can be characterized by the second grating period smaller than the first grating period. The eyepiece waveguide can be optically coupled to a projector operable to output red, green, and blue wavelengths, and the eyepiece waveguide can be operable to support light propagation at red, green, and blue wavelengths. The first region can be disposed on the world side surface opposite the third region disposed on the user side. The second region can be disposed on the world side surface opposite the fourth region disposed on the user side. The first in-coupling diffractive optical element and the second in-coupling diffractive optical element can be characterized by a grating vector k L and the third in-coupling diffractive optical element can be characterized by a grating vector k HIt can be characterized by, the first region and the third region can be characterized by the lattice vector k1, the second region can be characterized by the lattice vector k3, and the fourth region can be characterized by the lattice vector k2. The diffraction paths of the red wavelength and the green wavelength can be k L →k2→k3, and the diffraction path of the blue wavelength can be k H →k1→k2.

[0012] These and other embodiments of the present disclosure will be described in detail below, along with many of their advantages and functions, in the following text and corresponding figures.

Brief Description of the Drawings

[0013]

Figure 1A

Figure 1B

Figure 1C

Figure 1D

Figure 2A

Figure 2B

Figure 2C

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 4E

Figure 4F

Figure 4G

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 5E

Figure 5F

Figure 6A

Figure 6B

Figure 6C

Figure 6D

Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 8A

Figure 8B

Figure 8C

Figure 8D

Figure 9A

Figure 9B

Figure 9C

Figure 9D

Figure 10A

Figure 10B

Figure 10C

Figure 10D

Figure 11A

Figure 11B

Figure 11C

Figure 11D

Figure 12A

Figure 12B

Figure 12C

Figure 12D

Figure 13A

Figure 13B

Figure 13C

Figure 13D

Figure 14A

Figure 14B

Figure 14C

Figure 14D

Figure 15A

Figure 15B

Figure 15C

Figure 15D

Figure 16A

Figure 16B

Figure 16C

Figure 16D

Figure 17A

Figure 17B

Figure 17C

Figure 17D

Figure 17E

Figure 17F

Figure 18A

Figure 18B

Figure 18C

Figure 18D

Figure 19A

Figure 19B

Figure 19C

Figure 20A

Figure 20B

Figure 20C

Figure 21A

Figure 21B

Figure 21C

Figure 21D

Figure 22A

Figure 22B

Figure 23

Figure 24

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]

[0101] Multi-directional emission in the context of a diffractive waveguide combiner has mainly focused on, and has been relatively little studied, in a structure in which light is emitted from a projector along two opposing parallel directions. Most of the optical waveguides available on the market typically rely on unidirectional emission of light due to their simplicity and waveguide efficiency. In contrast to such prior art, the structures described herein (with many examples shown below) emit light from a projector in separate non-parallel directions. The embodiments described herein are useful in the context of an augmented reality (AR) system including an AR headset. Further description of AR headsets is provided in U.S. Patent Application Publication No. 2019 / 0179149, the disclosure of which is hereby incorporated by reference in its entirety for all purposes.

[0015]

[0102] In the embodiments described herein, the proposed multi-directional radiation waveguide design uniquely addresses some of the fundamental constraints on diffractive optical AR displays. For example, the field of view that can be achieved using a single waveguide layer for red, green, and blue wavelengths is partially limited and determined by the refractive index of the material. Further, due to the frequency / wavelength dependence of light propagation within the waveguide, the uniformity of the display is significantly impaired. The multi-directional radiation and multi-synthesizer designs described herein enable a field of view larger than the fundamental limitations and achieve a good uniformity profile. In other words, the complexity of multi-directional radiation is suitable for overcoming certain fundamental limitations of waveguide designs based on unidirectional radiation.

[0016]

[0103] Figures 1A - 1D illustrate the basic functions of an eyepiece waveguide based on unidirectional radiation, whereby an input coupling grating (ICG) couples light from a projector into the high refractive index medium (e.g., glass) of the eyepiece waveguide.

[0017]

[0104] Figure 1A is a simplified cross-sectional view showing the elements of an eyepiece waveguide according to an embodiment of the present invention. As shown in Figure 1A, the eyepiece waveguide 100 includes an input coupling grating (ICG) 110 formed in a first portion of the eyepiece waveguide, a grating structure 120 formed in a second portion on the world side of the eyepiece waveguide, and a combined pupil expander (CPE) including a grating structure 122 formed in a second portion on the user side of the eyepiece waveguide. Light is in-coupled into the eyepiece waveguide 100 using the ICG 110 and out-coupled towards the user using the CPE including the grating structure 120 and the grating structure 122.

[0018]

[0105] In the illustrated embodiment, the grating depth within the CPE varies according to the lateral position and increases as the distance from the ICG110 increases, thereby increasing the grating coupling efficiency according to the lateral position. In other embodiments, the grating depth, or other grating parameter related to the grating strength, is constant according to the lateral position. Thus, both the varying grating parameter and the constant grating parameter are included within the scope of the present invention. Further, although the figures herein do not depict a varying grating parameter, such as a varying grating depth, it will be understood that the grating parameter can vary in the embodiments described herein.

[0019]

[0106] 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. Referring to Figure 1B, the k-space diagram can be used to understand the flow of light using this momentum space representation. As shown in Figure 1B, the inner circle with radius = 1 shows the momentum of light at all physically possible angles of incidence in free space or vacuum. The outer circle with radius = the refractive index of the glass (in this case, n = 2) shows all physically possible angles of incidence within the eyepiece waveguide medium (e.g., glass). The field of view (FOV) corresponding to the projector is described by the extent of the barrel-shaped box shown in Figure 1B. Thus, light coupled or radiated into the glass has momentum in the annular region within the momentum space (i.e., between the inner r = n = 1 circle and the outer r = n = 2 circle), and by total internal reflection, this light will not exit the eyepiece waveguide unless and until this light interacts with the diffraction grating that changes its momentum. In the case of light in-coupled into the waveguide via the ICG110, the FOV corresponding to the projector (e.g., a 53° × 53° FOV) will be shifted in k-space as represented by the vector k ICG as shown.

[0020]

[0107] The lattice vectors in the k-space representation shown in FIG. 1B indicate not only the direction but also the pitch or lattice period with respect to a given design wavelength. For example, in the case of an eyepiece waveguide specifically designed for a green wavelength of 525 nm, the k-space representation shown in FIG. 1B corresponds to a k of a one-dimensional lattice with a pitch = 525 nm / 1.5 = 350 nm ICG having a radiation vector of = 1.5.

[0021]

[0108] In the case of a CPE having a 1D, binary, square ridge lattice, the diffraction vectors k1 and k2 are defined by the momentum translations of k1 and k2. The diffraction of light propagating within the eyepiece waveguide by these diffraction gratings enables, for example, spreading the emitted light over a wide area for, e.g., exit pupil expansion. At the same time, these gratings also out-couple the diffused light, which corresponds to the momentum conversion indicated by the dashed vectors in FIG. 1B. This out-coupled light is visible to the user's eye, and thereafter, digital content can be observed. Since the eyepiece waveguide can have patterns on both sides (i.e., facing both the user and the outside world), the implementation form can use either a 2D lattice defined by the momentum translations k1 and k2 on one side of the eyepiece waveguide, or a 1D lattice formed on each of one side of the two sides of the eyepiece waveguide.

[0022]

[0109] Note that referring to the k-space diagram shown in FIG. 1B, it is noted that light corresponding to the FOV that does not overlap with the annular region between r = n = 1 and r = n = 2 does not propagate by TIR. Therefore, only the portion of the FOV that overlaps with the annular region becomes accessible to the user.

[0023]

[0110] FIG. 1C is a simplified plan view of the world side of the eyepiece waveguide according to an embodiment of the present invention. Referring to FIG. 1C, the light in-coupled by the ICG110 travels vectorially k towards the CPE including the grating structure 120 and the grating structure 122 ICGPropagates as shown by

[0024]

[0111] FIG. 1D is a simplified plan view of the user side of the eyepiece waveguide shown in FIG. 1C. As described in connection with FIG. 1C, the grating depth within region 130 can 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 defined by the grating vector k2 within region 130, which diffracts light towards the lower side of the CPE and k within region 140, which diffracts light towards region 130 to provide a light reuse function. The grating vector k associated with this "reuse" grating is shown in FIG. 1B. rec towards the lower side of, which diffracts light towards region 130 to provide a light reuse function. The grating vector k associated with this "reuse" grating rec is shown in FIG. 1B.

[0025]

[0112] Referring to FIGS. 1C and 1D simultaneously, the light propagating within the eyepiece waveguide can be diffracted as represented by the grating vectors k1 and k2 so as to spread within the eyepiece waveguide as shown by the solid vectors k1 and k2 in FIG. 1B. Further, the light can also be diffracted as represented by the grating vectors k1 and k2 so as to out-couple towards the user as shown by the dashed vectors k1 and k2 in FIG. 1B. The periods of the CPE gratings coupled to the world side and the user side can be made equal in various directions, but this is not essential. Those skilled in the art will recognize many variations, modifications, and alternative forms.

[0026]

[0113] An eyepiece waveguide designed to provide good image quality for AR display at a green wavelength typically does not provide the same image quality for AR display at red and blue wavelengths due to the mismatch in grating pitch.

[0027]

[0114] Figure 2A is a simplified k-space diagram showing the field of view and lattice 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 utilizes a unidirectional emission structure and is designed for green wavelength operation at a 30°×30° FOV for all three wavelengths, namely red (628 nm), green (525 nm), and blue (455 nm).

[0028]

[0115] Figure 2B shows an enlarged view of a part of the k-space diagram shown in Figure 2A. As shown in Figure 2B, most of the red FOV is outside the outer circle with r = n = 2. As a result, the light in this non-overlapping region does not propagate within the waveguide and does not exist at the corresponding incident angles. For an eyepiece waveguide fabricated using glass with a refractive index of n = 2, the maximum square-shaped FOV that can be achieved is approximately 24°×24°.

[0029]

[0116] In addition to this basic limitation, another problem is that in a glass waveguide, not only due to the mismatch of lattice vectors and the wavelength dependence of diffraction, but also because the number of times the propagating light hits the lattice is different, the three different wavelengths interact with the lattice in completely different ways. In other words, the number of bounces between the two faces of the waveguide varies according to the wavelength. Generally, TIR light with a momentum value close to the inner r = n = 1 circle (e.g., the blue FOV in Figure 2A) bounces more frequently compared to TIR light with a momentum value close to the outer r = n = 2 circle (e.g., the red FOV in Figure 2A).

[0030]

[0117] Figure 2C is a plot showing the number of light reflections that occurred with a 2 mm propagation according to the angle. In the case of light with a 55°×55° FOV, emitted within an eyepiece waveguide with a thickness of 0.35 mm and n = 2.0, Figure 2C shows the number of reflections that occurred within a 2 mm propagation distance represented by the angle. The upper right corner of Figure 2C shows the momentum close to the outer r = n = 2 circle in k-space, and the lower left corner shows the momentum close to the inner r = n = 1 circle in k-space. The large difference in the reflection frequencies of these opposite scenarios causes a large discrepancy between the interaction with the diffraction grating and the red light propagation and blue light propagation inherent in the monolayer design. As a result, these constraints generally lead to problems of non-uniformity in the display. Therefore, embodiments of the present invention utilize a new type of structure that can avoid these fundamental discrepancies and provide improved performance.

[0031]

[0118] Figure 3A is a simplified k-space diagram showing the field of view and ICG lattice vectors of an eyepiece waveguide with multi-directional radiation 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 radiation according to an embodiment of the present invention. Figure 3C is a simplified plan view of the user side of the eyepiece waveguide with multi-directional radiation shown in Figure 3B. In addition to the ICG and CPE regions of the eyepiece waveguide, Figures 3B and 3C show the fan angle of the light radiated into the eyepiece waveguide using the ICG.

[0032]

[0119] An exemplary eyepiece waveguide with multi-directional radiation is shown in relation to Figures 3A - 3C, but it will be understood that multiple multi-directional radiation structures are included within the scope of the present invention. For the purposes of this explanation, a 30°×30° FOV is utilized.

[0033]

[0120] Referring to FIGS. 3B and 3C, this exemplary embodiment utilizes a multi-directional radiation IPE waveguide design, which uses separate ICG pupils arranged on the world side of the IPE waveguide shown as red ICG310, green ICG312, and blue ICG314 in FIG. 3B, together with the blue ICG320 arranged on the user side of the IPE waveguide shown in FIG. 3C. Thus, light from the projector is coupled into the IPE waveguide using these four ICGs. However, as will be fully explained below, the grating periods and corresponding grating vectors of the various ICGs designed for the green wavelength are different from the blue light (and blue ICG) compared to the red light and green light (as well as red ICG and green ICG). The embodiment shown in FIG. 3C includes the blue ICG320 arranged on the user side of the IPE waveguide, but this is not essential, and in some embodiments, the blue ICG320 is optional.

[0034]

[0121] As shown in FIG. 3A, the gratings corresponding to the grating vector k red and the grating vector k green are characterized by the same grating dimensions (i.e., the same grating period, e.g., 525 nm / ~1.5≒350 nm), while the grating corresponding to the grating vector k blue is characterized by larger grating dimensions (i.e., smaller grating period, e.g., 525 nm / ~1.9≒276 nm). Thus, in the case of the red ICG310 and the green ICG312, the light at the center of the FOV is diffracted within the IPE waveguide to generate a red FOV311 for the red wavelength and a green FOV313 for the green wavelength. Both of these FOVs are within the annular region defined by r=n=1 and r=n=2. The light diffracted within the IPE waveguide using the blue ICG314 coupled to the world side of the IPE waveguide or the blue ICG320 coupled to the user side of the IPE waveguide has a k blueDiffracts as represented by. Thus, for blue ICG314 and blue ICG320, the light at the center of the FOV is diffracted within the eyepiece waveguide to generate a blue FOV331. This FOV is within the annular region defined by r = n = 1 and r = n = 2.

[0035]

[0122] Referring to FIG. 3B, red light and green light are radiated into the eyepiece waveguide towards region 344 of CPE340, and the grating directions in red ICG310 and green ICG312 are oriented such that they are directed towards the lower left part of the CPE. Blue light is radiated into the eyepiece waveguide towards region 342 of CPE340 on the world side and towards region 352 of CPE350 on the user side, and the grating directions in blue ICG314 and blue ICG320 are oriented such that they are directed towards the upper left part of the CPE.

[0036]

[0123] 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 that should be diffracted by the blue ICG is diffracted into the green FOV330 that partially overlaps with the region outside the r = n = 2 circle. However, the light of the blue wavelength will be diffracted into the blue FOV331 within the annular region. Thus, since the respective frustum-shaped boxes corresponding to the red FOV311, green FOV313, and blue FOV331, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 30°×30° FOV.

[0037]

[0124] The grating vectors within the CPE, including grating vector k2 in region 344 of CPE340 and grating vector k3 in region 354 of CPE350, are designed such that light spreads within the waveguide and exits from the central region of the eyepiece.

[0038]

[0125] FIG. 3C shows the blue light that is coupled in by the blue ICG 320, which is coupled to the user side of the CPE 310 and diffracts within the CPE 350. However, this is not essential, and in some embodiments, the blue ICG 320 is optional.

[0039]

[0126] In FIGS. 3B and 3C, a specific diffraction structure is shown as being fabricated on both the world side and the user side. However, it should be noted that this is merely illustrative. In other embodiments, the diffraction structure shown as being coupled to the world side can be fabricated such that they are coupled to the user side, and the diffraction structure shown as being coupled to the user side can be fabricated such that they are coupled to the world side. Thus, the diffraction structure can be appropriately mounted on both sides for a particular application. Further, as will be fully described below, the diffraction structure can be fabricated such that they are coupled to one side of the eyepiece waveguide.

[0040]

[0127] FIG. 3D is a simplified plan view of a one-sided eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. The one-sided eyepiece waveguide shown in FIG. 3D shares common elements with the eyepiece waveguide shown in FIGS. 3B and 3C. In the embodiment shown in FIG. 3D, the region 346 includes a lattice corresponding to both the lattice vector k2 and the lattice vector k3. Thus, the functions described in connection with FIGS. 3B and 3C are implemented in the embodiment shown in FIG. 3D using a one-sided design.

[0041]

[0128] Note that the eyepiece waveguide can be manufactured using a substrate of a specific refractive index having a diffraction structure of a single refractive index or a diffraction structure in which various regions are characterized by various refractive indices. This can be achieved by drop-on-demand inkjet of UV / thermosetting resins of various indices before patterning with a template or within the region by a region patterning method such as using J-FIL (trademark) nanoimprinting technology. By depositing inorganic high refractive index materials such as Si3N4, ZrO2, TiO2 using a stencil mask, it is also possible to accommodate various refractive indices in various regions, and the deposition can be carried out using physical or chemical vapor deposition processes such as evaporation, sputtering, PECVD, ALD. As an example, in FIG. 3D, the CPE 340 can be manufactured such that the region 342 has a first refractive index and the region 346 has a second refractive index different from the first refractive index. Therefore, a lattice corresponding to various lattice vectors can be defined for various refractive indices in various regions.

[0042]

[0129] FIG. 4A is a simplified k-space diagram showing the field of view and CPE lattice vectors of an eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 4B is a simplified plan view of the world side of an eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 4C is a simplified plan view of the user side of the eyepiece waveguide with multi-directional radiation shown in FIG. 4B. In addition to the ICG and CPE regions of the eyepiece waveguide, FIGS. 4B and 4C show the fan angle of the light radiated into the eyepiece waveguide using the ICG. For comparison, FIG. 4A shows the lattice vectors corresponding to the CPE, while FIG. 3A shows the lattice vectors (i.e., radiation vectors) of the ICG.

[0043]

[0130] Referring to the k - space representation of the CPE lattice shown in Fig. 4A, as well as the plan views of the IPE waveguide shown in Figs. 4B and 4C, the blue light radiated towards the upper - left part of the CPE410 and hitting the lattice in the region 412 as shown in Fig. 4B diffracts as indicated by the lattice vector k1 and propagates towards the central part of the IPE waveguide, where it interacts with the lattice coupled to the user side (i.e., the region 424) of the CPE4250 and is out - coupled as indicated by the lattice vector k2. As shown in Fig. 4B, the lattice period in the region 412 is characterized by a smaller lattice period, e.g., 525nm / ~1.9≒276nm, compared to the lattice period in the region 414, e.g., 525nm / ~1.5≒350nm. For clarity, although various lattice periods are not shown in other figures including Fig. 4C, it will be understood that the lattice periods associated with various lattice vectors change appropriately for a particular application.

[0044]

[0131] As shown in Fig. 4C, the green and red light, which is radiated towards the lower - left part of the CPE410 and hits the lattice in the region 424 coupled to the user side of the CPE420, diffracts as indicated by the lattice vector k2 and, when interacting with the lattice (i.e., the region 414) coupled to the world side of the CPE410 as indicated by the lattice vector k3, is out - coupled. Thus, this embodiment utilizes lattices arranged on both the world side and the user side of the IPE waveguide as shown in Figs. 4B and 4C. It should be noted that the height of the lattice does not have to be constant, but can, for example, increase gradually, continuously or discretely, across the CPE, including a gradation zone.

[0045]

[0132] Since the eyepiece waveguide is designed for the green wavelength, the blue light within the blue FOV331 diffracts within region 412 along the lattice vector k1 such that the blue FOV430 is disposed within the annular region. Thus, outcoupling will occur such that the blue FOV430 is outcoupled to the user without clipping the FOV, as indicated by the lattice vector k2. The red light within the red FOV311 and the green light within the green FOV313 diffract within region 424 coupled to the user side of the eyepiece waveguide along the lattice vector k2 to form the red FOV440 and the green FOV442, both of which are disposed within the annular region. When interacting with the grating within region 414 coupled to the world side of the eyepiece waveguide, outcoupling occurs as represented by the lattice vector k3, resulting in outcoupling of the red FOV440 and the green FOV442 without clipping of the FOV. Note that the k-space diagram is referenced to the green wavelength, and as a result, the lattice vectors originate and terminate at the center of the green FOV.

[0046]

[0133] FIG. 4C shows blue light that is in-coupled by the blue ICG320, which is coupled to the user side of the CPE420 and diffracts within region 422, but this is not essential and in some embodiments the blue ICG406 is optional.

[0047]

[0134] One advantage provided by embodiments of the present invention that utilize a multi-directional emission design is equalizing the number of bounces for the red and blue wavelengths. As shown in FIG. 2C, light rays within the annulus having a momentum close to the inner circle strongly interact with the grating for multiple bounces. Light rays having a momentum close to the outer circle weakly interact with the grating due to grazing angles of incidence. In a unidirectional emission design, the red FOV is located near the outer circle while the blue FOV is located near the inner circle, thereby creating a large mismatch in the interaction with the CPE grating and ultimately resulting in display non-uniformity.

[0048]

[0135] In the multi-directional emission design of FIG. 4A, both the red FOV 440 and the blue FOV 331 are disposed near the outer r=n=2 circle, which significantly reduces this mismatch based on the number of bounces in the waveguide.

[0049]

[0136] On the other side of the illustrated eyepiece waveguide, in addition to implementing the illustrated diffraction structure, it is also possible to implement diffraction structures on both sides of the eyepiece waveguide. As an example, the diffraction structure shown in FIG. 3D can be implemented on both the world side and the user side of the eyepiece waveguide. Further, the diffraction structure shown in FIG. 4B can be implemented on the first side (e.g., either the world side or the user side) of the eyepiece waveguide, and the diffraction structure shown in FIG. 3D can be implemented on the second side (e.g., either the user side or the world side) of the eyepiece waveguide. Further, the diffraction structure shown in FIG. 3D can be implemented on the first side (e.g., either the world side or the user side) of the eyepiece waveguide, and the diffraction structure shown in FIG. 4C can be implemented on the second side (e.g., either the user side or the world side) of the eyepiece waveguide. Those skilled in the art will recognize many variations, modifications, and alternative forms.

[0050]

[0137] Figure 4D is a simplified top view of the world side of an IOL waveguide including a two-dimensional lattice with multi-directional radiation according to an embodiment of the present invention. Figure 4E is a simplified top view of the user side of the IOL waveguide including a two-dimensional lattice with multi-directional radiation shown in Figure 4D. The IOL waveguide shown in Figure 4D shares common elements with the IOL waveguide shown in Figure 4B, and the IOL waveguide shown in Figure 4E shares common elements with the IOL waveguide shown in Figure 4C. In addition to the elements described in connection with Figures 4B and 4C, region 452 of CPE 450 includes a lattice corresponding to lattice vector k4, and region 462 of CPE 460 includes a lattice corresponding to lattice vector k5. As described in connection with Figures 4F and 4G, the addition of the lattices corresponding to lattice vectors k4 and k5 introduces additional diffraction paths that facilitate diffraction in the plane of the IOL waveguide as well as out-coupling from the IOL waveguide.

[0051]

[0138] Figure 4F is a simplified k-space diagram showing the field of view and CPE lattice vectors of the IOL waveguide with multi-directional radiation shown in Figures 4D and 4E according to an embodiment of the present invention.

[0052]

[0139] Referring to Figure 4F, the light in-coupled by the red ICG 310 is diffracted within the IOL waveguide to generate the red FOV 311. Diffraction by the lattice corresponding to lattice vector k2 results in a shift of the red FOV 311 to the FOV 471, which can be out-coupled as a result of diffraction from the lattice corresponding to lattice vector k3. If the light is not out-coupled by lattice vector k3, diffraction from the lattice corresponding to lattice vector k5 results in a shift of the FOV 471 to the FOV 472, which can be out-coupled as a result of diffraction from the lattice corresponding to lattice vector k4.

[0053]

[0140] Diffraction by the lattice corresponding to the lattice vector k3 results in a shift to FOV474 or FOV475 of the red FOV311 that can be out-coupled as a result of diffraction from the lattices corresponding to the lattice vectors k2 and k5, respectively. If the light is not out-coupled by the lattice vector k2 or the lattice vector k5, diffraction from the lattice corresponding to the lattice vector k4 results in shifts to FOV473 of FOV474 and to FOV471 of FOV475 that can be out-coupled as a result of diffraction from the lattice corresponding to the lattice vector k3. Similar diffraction paths can be described for the green FOV311 and the blue FOV331. These diffraction paths are merely illustrative and do not cover all the various diffraction paths provided by embodiments of the present invention.

[0054]

[0141] Figure 4G is a simplified k-space diagram showing the field of view and the CPE lattice vectors of the eyepiece waveguide with multi-directional emission shown in Figures 4D and 4E, according to another embodiment of the present invention.

[0055]

[0142] Referring to FIG. 4G, the light in-coupled by the red ICG 310 is diffracted in the eyepiece waveguide to generate a red FOV 311. Diffraction by the grating corresponding to the lattice vector k2 results in a shift of the red FOV 311 to the FOV 480 of the red FOV 311, which can be out-coupled as a result of diffraction from the grating corresponding to the lattice vector k3. If the light is not out-coupled by the lattice vector k3, diffraction from the grating corresponding to the lattice vector k4 results in a shift of the FOV 480 to the FOV 486 of the FOV 480, which can be out-coupled as a result of diffraction from the grating corresponding to the lattice vector k5 or a shift of the FOV 480 to the FOV 481. Diffraction from the grating corresponding to the lattice vector k3 results in a shift of the FOV 481 to the FOV 482, which can be out-coupled as a result of diffraction from the grating corresponding to the lattice vector k4. Alternatively, diffraction from the grating corresponding to the lattice vector k1 results in a shift of the FOV 481 to the FOV 483, which can be out-coupled as a result of diffraction from the grating corresponding to the lattice vector k5. If the light is not out-coupled by the lattice vector k5, diffraction from the grating corresponding to the lattice vector k4 results in a shift of the FOV 483 to the FOV 484, which can be out-coupled as a result of diffraction from the grating corresponding to the lattice vector k3.

[0056]

[0143] When returning to FOV480, the diffraction by the lattice corresponding to the lattice vector k5 can result in out-coupling as a result of the diffraction from the lattice corresponding to the lattice vector k4, causing a shift of FOV480 to FOV482. If the light is not out-coupled by the lattice vector k4, the diffraction from the lattice corresponding to the lattice vector k2 can result in out-coupling as a result of the diffraction from the lattice corresponding to the lattice vector k3, causing a shift of FOV482 to FOV484. When returning to FOV486, the diffraction by the lattice corresponding to the lattice vector k1 can result in out-coupling as a result of the diffraction from the lattice corresponding to the lattice vector k2, causing a shift of FOV486 to FOV485. Similarly, the diffraction by the lattice corresponding to the lattice vector k1 can result in out-coupling as a result of the diffraction from the lattice corresponding to the lattice vector k3, causing a shift of FOV480 to FOV484. If the light is not out-coupled by the lattice vector k3, the diffraction from the lattice corresponding to the lattice vector k2 can result in out-coupling as a result of the diffraction from the lattice corresponding to the lattice vector k4, causing a shift of FOV484 to FOV482, or the diffraction from the lattice corresponding to the lattice vector k4 can result in out-coupling as a result of the diffraction from the lattice corresponding to the lattice vector k5, causing a shift of FOV484 to FOV483. Similar diffraction paths can be described for the green FOV311 and the blue FOV331. Furthermore, these diffraction paths are merely illustrative and do not cover all the various diffraction paths provided by the embodiments of the present invention.

[0057]

[0144] Referring back to FIG. 3D, the lattices corresponding to lattice vectors k4 and k5 can be added to region 342 of CPE350 in a single-sided design. In a double-sided design, the lattice corresponding to lattice vector k4 can be added either on the world side or the user side to region 342 of CPE340, and the lattice corresponding to lattice vector k5 can be added either on the user side or the world side to region 342 of CPE340 to implement a two-dimensional lattice in both region 342 and region 346. The addition of the lattices corresponding to lattice vectors k4 and k5 introduces additional diffraction paths in both the single-sided and double-sided designs that facilitate in-plane diffraction of the eyepiece waveguide and out-coupling from the eyepiece waveguide.

[0058]

[0145] FIGS. 5A-5C show the normalized efficiency distributions for the red, green, and blue wavelengths, respectively, for a unidirectional emission design according to an embodiment of the present invention. In these figures, the optical performance of the waveguide structure is characterized for an eyepiece waveguide similar to that shown in FIG. 1C. FIGS. 5A-5C show the efficiency distributions over a 30°×30° field of view for the unidirectional emission design for the red, green, and blue wavelengths, respectively.

[0059]

[0146] Referring to FIG. 5A, the user-side eyebox efficiency (U EBE ) and the world-side eyebox efficiency (W EBE ) for the red wavelength are shown. U EBE and W EBE represent the percentage of the total incident power from the projector that ultimately reaches the eyebox plane at the nominal distance of the eye from the waveguides on both sides of the eyepiece. The efficiency distribution is non-uniform because light rays corresponding to various angles of incidence spread within the waveguide and interact differently than the lattices. The display uniformity can be represented by the 80-20 percentile score over the inner 80% of the field of view, as shown by U inner80 . U inner80It is the ratio of the difference between the 80th percentile and the 20th percentile to the 50th percentile (i.e., the median). U inner80 The lower the value of, the better the uniformity is indicated. FIG. 5B shows the U of the green wavelength EBE and W EBE FIG. 5C shows the U of the blue wavelength EBE and W EBE U inner80 is equal to 1.868 for the red wavelength, equal to 0.699 for the green wavelength, and equal to 2.110 for the blue wavelength. Region R1 in FIG. 5A, and regions R2 and R3 in FIG. 5C show the cut-out portions of the field of view where the light intensity is zero.

[0060]

[0147] FIGS. 5D to 5F show the normalized efficiency distributions of the red wavelength, the green wavelength, and the blue wavelength for the multi-directional radiation design according to an embodiment of the present invention. In these figures, the optical performance of the waveguide structure is characterized for an eyepiece waveguide similar to that shown in FIGS. 3A / 3B. FIGS. 5A to 5C show the efficiency distributions over a 30°×30° field of view for the multi-directional radiation design of the red wavelength, the green wavelength, and the blue wavelength, respectively.

[0061]

[0148] Comparing FIGS. 5D to 5F with FIGS. 5A to 5C, U inner80 is equal to 1.184 for the red wavelength, equal to 1.388 for the green wavelength, and equal to 0.0892 for the blue wavelength. Importantly, while the regions marked as R1, R2, and R3 in FIGS. 5A to 5C show the clipping of the 30°×30° field of view for the unidirectional radiation design, such clipping does not exist in FIGS. 5D to 5F, indicating that the field of view limitation is overcome by the multi-directional radiation structure.

[0062]

[0149] The efficiency distribution is non-uniform, but the color correction algorithm adjusts the weights corresponding to various incident angles within the FOV in order to obtain good color (white) uniformity for AR display. Furthermore, the center-to-peak ratio (i.e., the efficiency at the center divided by the peak efficiency, with an ideal value = 1) indicates the centrality of the efficiency distribution across the FOV.

[0063]

[0150] Table 1 presents yet another comparison between the unidirectional emission design and the multi-directional emission design, which calculates the maximum achievable FOV based on the k-space diagram, thereby ensuring that the square FOV is completely within the annulus of the 2.0 pitch waveguide. For these calculations, it is assumed that for both the unidirectional and multi-directional emission designs, the ICG or projector is located above the center of the temple side, enabling a large real-world FOV, equal horizontal (H) and vertical (V) ranges of the FOV, as well as a constant value of the refractive index for all wavelengths. As is evident from Table 1, the multi-directional emission design has distinct fundamental advantages with respect to the maximum achievable digital FOV.

Table 1

[0064]

[0151] Note that for light emitted into the waveguide via a projector utilizing various ICG arrangements (i.e., various emission angles), the maximum achievable diagonal FOV varies for both types of designs. However, it can be shown that the multi-directional emission design always results in a larger possible FOV than the unidirectional emission design.

[0065]

[0152] In connection with FIGS. 6A - 16D, it shows the k - space representations of the ICG lattice and the CPE lattice, as well as the CPE layout showing the lattice positions of each of several multi - direction radiative waveguide structures. Further, it describes the minimum sequence of diffraction events that direct projector light towards the user's eye at a red wavelength, a green wavelength, or a blue wavelength. The k - space representation is for a 30°×30° FOV having an eyepiece waveguide with a refractive index of n = 2.0 and three separate ICG pupils for the red, green, and blue wavelengths. The lattice vectors are normalized with respect to the green free - space momentum.

[0066]

[0153] FIG. 6A is a simplified k - space diagram showing the field of view and the ICG lattice vectors of a first eyepiece waveguide with multi - direction radiation according to an embodiment of the present invention. FIG. 6B is a simplified k - space diagram showing the field of view and the CPE lattice vectors of a first eyepiece waveguide with multi - direction radiation according to an embodiment of the present invention. FIG. 6C is a simplified plan view of the world side of a first eyepiece waveguide with multi - direction radiation according to an embodiment of the present invention. FIG. 6D is a simplified plan view of the user side of the first eyepiece waveguide with multi - direction radiation shown in FIG. 6C.

[0067]

[0154] Referring initially to FIGS. 6C and 6D, this first IPECE waveguide utilizes a multi-directional radiation IPECE waveguide design, which uses separate ICG pupils coupled to the world side of the IPECE waveguide shown as red ICG610, green ICG612, and blue ICG614 in FIG. 6C, along with red ICG611, green ICG613, and blue ICG615 coupled to the user side of the IPECE waveguide as shown in FIG. 6D. Thus, light from the projector is coupled into the IPECE waveguide using these six ICGs. However, as will be fully explained below, the lattice periods and corresponding lattice vectors of the various ICGs designed for the green wavelength are different from the blue light (and blue ICG) compared to the red light and green light (as well as red ICG and green ICG). The embodiment shown in FIG. 6D includes red ICG611, green ICG613, and blue ICG615 coupled to the user side of the IPECE waveguide, but this is not essential, and in some embodiments, red ICG611, green ICG613, and blue ICG615 are optional.

[0068]

[0155] Referring to FIG. 6A, the lattice vector k H represents diffraction by a large distance (High) in k-space, and the lattice vector k L represents diffraction by a small distance (Low) in k-space. Thus, the lattice corresponding to the lattice vector k L is characterized by the same lattice dimension (i.e., the same lattice period, e.g., 525 nm / ~1.5≒350 nm), while the lattice corresponding to the lattice vector k H is characterized by a large lattice dimension (i.e., a small lattice period, e.g., 525 nm / ~1.9≒276 nm). Thus, in the case of the red ICG610 and green ICG612 coupled to the world side of the IPECE waveguide, or the red ICG611 and green ICG613 coupled to the user side of the IPECE waveguide, the light at the center of the FOV is the lattice vector k LIt is diffracted into the eyepiece waveguide as shown, generating a red FOV630 for the red wavelength and a green FOV632 for the green wavelength. Both of these FOVs are arranged within the annular region between r = n = 1 and r = n = 2. The light diffracted into the eyepiece waveguide using the blue ICG614 coupled to the world side of the eyepiece waveguide or the blue ICG615 coupled to the user side of the eyepiece waveguide is diffracted as represented by k H diffracts as shown by. Thus, in the case of the blue ICG614 coupled to the world side of the eyepiece waveguide and the blue ICG615 coupled to the user side, the light at the center of the FOV is diffracted into the eyepiece waveguide, generating a blue FOV634 for the blue wavelength. This FOV is arranged within the annular region between r = n = 1 and r = n = 2. Thus, since the respective frustum-shaped boxes corresponding to the red FOV630, green FOV632, and blue FOV634, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 30°×30° FOV.

[0069]

[0156] Referring to FIG. 6C, the grating directions in the red ICG610 and green ICG612, as well as in the red ICG611 and green ICG613, are oriented such that the red and green light is radiated into the eyepiece waveguide toward the region 644 of the CPE640 and toward the region 654 of the CPE650. The grating directions in the blue ICG611 and blue ICG620 are oriented such that the blue light is radiated into the eyepiece waveguide toward the region 642 of the CPE640 on the world side and toward the region 652 of the CPE650 on the user side.

[0070]

[0157] Referring to FIGS. 6B and 6D, the red and green light radiated towards region 654 of CPE650 strikes the grating corresponding to lattice vector k2, thereby diffracting in the plane of the eyepiece waveguide (i.e., laterally within the eyepiece waveguide). As a result, the red FOV630 shifts to red FOV631 in k-space, and the green FOV632 shifts to green FOV633 in k-space. Diffraction in region 644 from the grating corresponding to lattice vector k3 results in out-coupling from the eyepiece waveguide. The blue light radiated towards region 642 within CPE640 and region 652 within CPE650 strikes the grating corresponding to lattice vector k1 within regions 642 and 652, thereby diffracting in the plane of the eyepiece waveguide. As a result, the blue FOV634 shifts to blue FOV635 in k-space. Diffraction in region 654 from the grating corresponding to lattice vector k2 results in out-coupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths showing the minimum sequence of interactions with the various grating types as the incident light propagates from the projector to the user's eye are k L →k2→k3. The diffraction path for the blue wavelength is k H →k1→k2.

[0071]

[0158] As shown in FIGS. 6A and 6B, the red FOV630 / 631, green FOV632 / 633, and blue FOV634 / 635 are all located within the annular region between r = n = 1 and r = n = 2. Thus, propagation and out-coupling in the plane of the eyepiece waveguide are performed without clipping of the FOV.

[0072]

[0159] FIG. 7A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a second eye-piece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 7B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a second eye-piece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 7C is a simplified plan view of the world side of a second eye-piece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 7D is a simplified plan view of the user side of the second eye-piece waveguide with multi-directional radiation shown in FIG. 7C.

[0073]

[0160] Referring first to FIGS. 7C and 7D, this second eye-piece waveguide utilizes a multi-directional radiation eye-piece waveguide design, which involves a single ICG pupil coupled to the world side of the eye-piece waveguide, shown as the first ICG 710 in FIG. 7C, being utilized with a second ICG 711 coupled to the user side of the eye-piece waveguide as shown in FIG. 7D. Thus, light from the projector is coupled into the eye-piece waveguide using these two ICGs. In the illustrated embodiment, both ICGs are disposed at the same position within the x-y plane (also referred to as the lateral plane), and all wavelengths (e.g., red, green, and blue wavelengths) are radiated from each ICG, with the various wavelengths being radiated in various directions.

[0074]

[0161] In one embodiment, the first ICG 710 and the second ICG 711 are each implemented as a two-dimensional diffraction structure (e.g., a two-dimensional lattice, nanostructure, etc.) that radiates light in two directions represented by lattice vectors k H and k L . In another embodiment, the first ICG 710 radiates light in a first direction (e.g., k H ), and the second ICG 711 radiates light in a second direction (e.g., k L ). The single ICG design is particularly suitable for use in a micro-LED display where the primary colors cannot be easily spatially separated. Thus, light from the micro-LED display can be imaged onto a single ICG.

[0075]

[0162] Referring to FIG. 7A, the lattice vector k H represents diffraction due to a large distance (High) in k-space, and the lattice vector k L represents diffraction due to a small distance (Low) in k-space. Accordingly, the first ICG710 coupled to the world side of the eyepiece waveguide and the second ICG711 coupled to the user side of the eyepiece waveguide couple light in a plurality of wavelengths and a first direction range (corresponding to the lattice vector k H ) to generate a red FOV720, a green FOV722, and a blue FOV724, and couple light in a plurality of wavelengths and a second direction range (corresponding to the lattice vector k L ) to generate a red FOV721, a green FOV723, and a blue FOV725 (to the extent that some or all of these FOVs are supported by the eyepiece waveguide). Referring to FIG. 7A, the blue FOV724, the green FOV723, and the red FOV721 are disposed within an annular region between r = n = 1 and r = n = 2. The red FOV720, the green FOV722, and the blue FOV725 include portions disposed within the annular region between r = n = 1 and r = n = 2. Note that the change in the refractive index of the eyepiece waveguide material (e.g., refractive index 2.5) will vary with the amount of FOV included in the annular region.

[0076]

[0163] Referring to FIG. 7B, the light present in the red FOV 720, green FOV 722, and blue FOV 724 is diffracted in regions 742 of the CPE 740 coupled to the world side and regions 752 of the CPE 750 coupled to the user side, hits a grating corresponding to the lattice vector k1, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 720 is shifted to the red FOV 731 in k-space, the green FOV 722 is shifted to the green FOV 733 in k-space, and the blue FOV 724 is shifted to the blue FOV 735 in k-space. Diffraction in region 754 of the CPE 750 from the grating corresponding to the lattice vector k2 results in out-coupling from the eyepiece waveguide. The light present in the red FOV 721, green FOV 723, and blue FOV 724 is diffracted in region 754 of the CPE 750 coupled to the user side, hits a grating corresponding to the lattice vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 721 is shifted to the red FOV 730 in k-space, the green FOV 723 is shifted to the green FOV 732 in k-space, and the blue FOV 725 is shifted to the blue FOV 734 in k-space. Diffraction in region 744 of the CPE 740 from the grating corresponding to the lattice vector k3 results in out-coupling from the eyepiece waveguide.

[0077]

[0164] Thus, the diffraction paths of the red, green, and blue wavelengths in-coupled by the first ICG 710 and the second ICG 711 in the direction represented by the lattice vector k, showing the minimum sequence of interactions with various grating types when the incident light propagates from the projector to the user's eye, H are k H →k1→k2. The diffraction paths of the red, green, and blue wavelengths in-coupled by the first ICG 710 and the second ICG 711 in the direction represented by the lattice vector k L are k L →k2→k3.

[0078]

[0165] FIG. 8A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a third IPEACE waveguide with multi-directional radiation, according to one embodiment of the present invention. FIG. 8B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a third IPEACE waveguide with multi-directional radiation, according to one embodiment of the present invention. FIG. 8C is a simplified plan view of the world side of a third IPEACE waveguide with multi-directional radiation, according to one embodiment of the present invention. FIG. 8D is a simplified plan view of the user side of the third IPEACE waveguide with multi-directional radiation shown in FIG. 8C.

[0079]

[0166] Referring first to FIGS. 8C and 8D, this third IPEACE waveguide utilizes a multi-directional radiation IPEACE waveguide design, which involves separate ICG pupils coupled to the world side of the IPEACE waveguide, shown as red ICG 810, green ICG 812, and blue ICG 814 in FIG. 8C, being utilized together with red ICG 811, green ICG 813, and blue ICG 815 coupled to the user side of the IPEACE waveguide as shown in FIG. 8D. Thus, light from the projector is coupled into the IPEACE waveguide using these six ICGs. However, as will be fully explained below, the lattice periods and corresponding lattice vectors of the various ICGs designed for the green wavelength are different for blue light (and blue ICG) compared to red and green light (and red and green ICG). The embodiment shown in FIG. 8D includes red ICG 811, green ICG 813, and blue ICG 815 coupled to the user side of the IPEACE waveguide, but this is not essential, and in some embodiments, red ICG 811, green ICG 813, and blue ICG 815 are optional.

[0080]

[0167] Referring to FIG. 8A, lattice vector k H represents diffraction by a large distance (High) in k-space, and lattice vector k L represents diffraction by a small distance (Low) in k-space. Thus, lattice vector k LThe lattice corresponding to is characterized by the same lattice dimension (i.e., the same lattice period, e.g., 525 nm / ~1.5≒350 nm), while the lattice vector k H The lattice corresponding to is characterized by a large lattice dimension (i.e., a small lattice period, e.g., 525 nm / ~1.9≒276 nm). Therefore, in the case of the red ICG810 and green ICG812 coupled to the world side of the eyepiece waveguide, or the red ICG811 and green ICG813 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide as represented by the lattice vector k L to generate a red FOV830 for the red wavelength and a green FOV832 for the green wavelength. Both of these FOVs are arranged within the annular region between r=n=1 and r=n=2. The light diffracted into the eyepiece waveguide using the blue ICG814 coupled to the world side of the eyepiece waveguide or the blue ICG815 coupled to the user side of the eyepiece waveguide is diffracted as represented by k H Therefore, in the case of the blue ICG814 coupled to the world side of the eyepiece waveguide and the blue ICG815 coupled to the user side, the light at the center of the FOV is diffracted into the eyepiece waveguide to generate a blue FOV834 for the blue wavelength. This FOV is arranged within the annular region between r=n=1 and r=n=2. Therefore, since the respective barrel-shaped boxes corresponding to the red FOV830, green FOV832, and blue FOV834, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 30°×30° FOV.

[0081]

[0168] Referring to FIG. 8C, the directions of the gratings in red ICG810 and green ICG812, as well as in red ICG811 and green ICG813, are oriented such that red light and green light are radiated into the eyepiece waveguide towards region 842 of CPE840 on the world side and towards region 852 of CPE850 on the user side. The directions of the gratings in blue ICG811 and blue ICG820 are oriented such that blue light is radiated into the eyepiece waveguide towards region 844 of CPE840 on the world side and towards region 854 of CPE850 on the user side.

[0082]

[0169] Referring to FIGS. 8B and 8D, the red light and green light radiated towards region 852 of CPE850 hit the grating corresponding to lattice vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, red FOV830 shifts to red FOV831 in k-space, and green FOV832 shifts to green FOV833 in k-space. Diffraction in region 842 from the grating corresponding to lattice vector k3 results in out-coupling from the eyepiece waveguide. The blue light radiated towards region 844 in CPE840 and region 854 in CPE850 hits the grating corresponding to lattice vector k1 in regions 844 and 854, thereby diffracting in the plane of the eyepiece waveguide. As a result, blue FOV834 shifts to blue FOV835 in k-space. Diffraction in region 852 from the grating corresponding to lattice vector k2 results in out-coupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths showing the minimum sequence of interactions with the various grating types when the incident light propagates from the projector to the user's eye are k L →k2→k3. The diffraction path for the blue wavelength is k H→k1→k2. Note that the CPE regions 844 and 854 have the same lattice, and one or both of them can be used in this multi-directional radiation structure. If only one of them exists, i.e., either 854 or 844, the CPE on the opposite side will have the respective extended lattice regions 842 or 852.

[0083]

[0170] As shown in FIGS. 8A and 8B, the red FOVs 830 / 831, the green FOVs 832 / 833, and the blue FOVs 834 / 835 are all arranged within the annular region between r = n = 1 and r = n = 2. Therefore, the in-plane propagation and out-coupling of the eyepiece waveguide are implemented without clipping of the FOV.

[0084]

[0171] FIG. 9A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a fourth eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 9B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a fourth eyepiece waveguide with multi-directional radiation 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 radiation according to an embodiment of the present invention. FIG. 9D is a simplified plan view of the user side of the fourth eyepiece waveguide with multi-directional radiation shown in FIG. 9C.

[0085]

[0172] Referring first to FIGS. 9C and 9D, this fourth eyepiece waveguide utilizes a multi-directional radiation eyepiece waveguide design, which means that a single ICG pupil coupled to the world side of the eyepiece waveguide shown as the first ICG 910 in FIG. 9C is utilized together with a second ICG 911 coupled to the user side of the eyepiece waveguide as shown in FIG. 9D. Therefore, the light from the projector is coupled to the eyepiece waveguide using these two ICGs. In the illustrated embodiment, both ICGs are arranged at the same position in the x-y plane, and all wavelengths (e.g., red wavelength, green wavelength, and blue wavelength) are radiated from each ICG, and the various wavelengths are radiated in various directions.

[0086]

[0173] In one embodiment, the first ICG 910 and the second ICG 911 are each implemented as a two-dimensional diffraction structure (e.g., a two-dimensional grating, nanostructure, etc.) that emits light in two directions represented by lattice vectors k H and k L . In another embodiment, the first ICG 910 emits light in a first direction (e.g., k H ), and the second ICG 911 emits light in a second direction (e.g., k L ). A single ICG design is particularly suitable for use in a micro-LED display where the primary colors cannot be easily spatially separated. Thus, the light from the micro-LED display can be imaged onto a single ICG.

[0087]

[0174] Referring to FIG. 9A, the lattice vector k H represents diffraction by a large distance (High) in k-space, and the lattice vector k L represents diffraction by a small distance (Low) in k-space. Thus, the first ICG 910 coupled to the world side of the eyepiece waveguide and the second ICG 911 coupled to the user side of the eyepiece waveguide couple light at a plurality of wavelengths and a first direction range (corresponding to the lattice vector k H ) to generate a red FOV 920, a green FOV 922, and a blue FOV 924, and couple light at a plurality of wavelengths and a second direction range (corresponding to the lattice vector k L ) to generate a red FOV 921, a green FOV 923, and a blue FOV 925 (to the extent that some or all of these FOVs are supported by the eyepiece waveguide). Referring to FIG. 9A, the blue FOV 925, the green FOV 922, and the red FOV 920 are disposed within an annular region between r = n = 1 and r = n = 2. The red FOV 921, the green FOV 923, and the blue FOV 924 include portions disposed within the annular region between r = n = 1 and r = n = 2. Note that the change in the refractive index of the eyepiece waveguide material (e.g., refractive index 2.5) will vary with the amount of FOV included in the annular region.

[0088]

[0175] Referring to FIG. 9B, the light present in the red FOV 920, green FOV 922, and blue FOV 924 is diffracted in region 952 of the CPE 950 coupled to the user side, hits the grating corresponding to the grating vector k2, and thereby diffracts in the plane of the eyepiece waveguide. As a result, the red FOV 920 shifts to the red FOV 931 in k-space, the green FOV 922 shifts to the green FOV 933 in k-space, and the blue FOV 924 shifts to the blue FOV 935 in k-space. Diffraction in region 942 of the CPE 940 from the grating corresponding to the grating vector k3 results in out-coupling from the eyepiece waveguide. The light present in the red FOV 921, green FOV 923, and blue FOV 925 is diffracted in region 944 of the CPE 940 coupled to the world side and region 954 of the CPE 950 coupled to the user side, hits the grating corresponding to the grating vector k1, and thereby diffracts in the plane of the eyepiece waveguide. As a result, the red FOV 921 shifts to the red FOV 930 in k-space, the green FOV 923 shifts to the green FOV 932 in k-space, and the blue FOV 924 shifts to the blue FOV 934 in k-space. Diffraction in region 942 of the CPE 940 from the grating corresponding to the grating vector k2 results in out-coupling from the eyepiece waveguide.

[0089]

[0176] Thus, the diffraction paths of the red, green, and blue wavelengths in-coupled by the first ICG 910 and the second ICG 911 in the direction represented by the grating vector k, which shows the minimum sequence of interactions with various grating types when the incident light propagates from the projector to the user's eye L are k L →k1→k2. The diffraction paths of the red, green, and blue wavelengths in-coupled by the first ICG 910 and the second ICG 911 in the direction represented by the grating vector k H are k H→k2→k3. Similar to the previous design, one of the lattice regions, for example, region 944 or region 954, can be considered optional and can be replaced by the respective lattice regions on the world side or the user side of the IPE waveguide.

[0090]

[0177] FIG. 10A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a fifth IPE waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 10B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a fifth IPE waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 10C is a simplified plan view of the world side of a fifth IPE waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 10D is a simplified plan view of the user side of the fifth IPE waveguide with multi-directional radiation shown in FIG. 10C.

[0091]

[0178] Referring first to FIGS. 10C and 10D, this fifth IPE waveguide utilizes a multi-directional radiation IPE waveguide design, which uses separate ICG pupils coupled to the world side of the IPE waveguide shown as red ICG 1010, green ICG 1012, and blue ICG 1014 in FIG. 10C, along with red ICG 1011, green ICG 1013, and blue ICG 1015 coupled to the user side of the IPE waveguide as shown in FIG. 10D. Thus, light from the projector is coupled to the IPE waveguide using these six ICGs. However, as will be fully explained below, the lattice periods and corresponding lattice vectors of the various ICGs designed for the green wavelength are different for blue light (and blue ICG) compared to red light and green light (and red ICG and green ICG). The embodiment shown in FIG. 10D includes red ICG 1011, green ICG 1013, and blue ICG 1015 coupled to the user side of the IPE waveguide, but this is not essential, and in some embodiments, red ICG 1011, green ICG 1013, and blue ICG 1015 are optional.

[0092]

[0179] Referring to Fig. 10A, the lattice vector k H represents diffraction due to a large distance (High) in k-space, and the lattice vector k L represents diffraction due to a small distance (Low) in k-space. Therefore, the lattice corresponding to the lattice vector k L is characterized by the same lattice dimension (i.e., the same lattice period, e.g., 525 nm / ~1.5≒350 nm), while the lattice corresponding to the lattice vector k H is characterized by a large lattice dimension (i.e., a small lattice period, e.g., 525 nm / ~1.9≒276 nm). Therefore, in the case of the red ICG1010 and green ICG1012 coupled to the world side of the eyepiece waveguide, or the red ICG1011 and green ICG1013 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide as represented by the lattice vector k L to generate a red FOV1030 for the red wavelength and a green FOV1032 for the green wavelength. Both of these FOVs are arranged within the annular region between r=n=1 and r=n=2. The light diffracted into the eyepiece waveguide using the blue ICG1014 coupled to the world side of the eyepiece waveguide or the blue ICG1015 coupled to the user side of the eyepiece waveguide is diffracted as represented by k H . Therefore, in the case of the blue ICG1014 coupled to the world side of the eyepiece waveguide and the blue ICG1015 coupled to the user side, the light at the center of the FOV is diffracted into the eyepiece waveguide to generate a blue FOV1034 for the blue wavelength. This FOV is arranged within the annular region between r=n=1 and r=n=2. Therefore, since the respective barrel-shaped boxes corresponding to the red FOV1030, green FOV1032, and blue FOV1034, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 30°×30° FOV.

[0093]

[0180] Referring to FIG. 10C, the directions of the gratings in the red ICG 1010 and green ICG 1012, as well as in the red ICG 1011 and green ICG 1013, are oriented such that red light and green light are radiated into the eyepiece waveguide towards the region 1042 of the CPE 1040 on the world side and towards the region 1052 of the CPE 1050 on the user side. The directions of the gratings in the blue ICG 1014 and blue ICG 1015 are oriented such that blue light is radiated into the eyepiece waveguide towards the region 1044 of the CPE 1040 on the world side and towards the region 1054 of the CPE 1050 on the user side.

[0094]

[0181] Referring to FIGS. 10B and 10D, the red light and green light radiated towards the region 1052 of the CPE 1050 hit the grating corresponding to the lattice vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 1030 shifts to the red FOV 1031 in k-space, and the green FOV 1032 shifts to the green FOV 1033 in k-space. Diffraction in the region 1042 from the grating corresponding to the lattice vector k3 results in out-coupling from the eyepiece waveguide. The blue light radiated towards the region 1044 within the CPE 1040 and the region 1054 within the CPE 1050 hits the grating corresponding to the lattice vector k1 within the regions 1044 and 1054, thereby diffracting in the plane of the eyepiece waveguide. As a result, the blue FOV 1034 shifts to the blue FOV 1035 in k-space. Diffraction in the region 1052 from the grating corresponding to the lattice vector k2 results in out-coupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths showing the minimum sequence of interactions with the various grating types when the incident light propagates from the projector to the user's eye are k L →k2→k3. The diffraction path for the blue wavelength is k H →k1→k2.

[0095]

[0182] As shown in FIGS. 10A and 10B, the red FOVs 1030 / 1031, green FOVs 1032 / 1033, and blue FOVs 1034 / 1035 are all disposed within the annular region between r = n = 1 and r = n = 2. Therefore, propagation and out-coupling within the plane of the eyepiece waveguide are performed without clipping of the FOV.

[0096]

[0183] FIG. 11A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a sixth eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 11B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a sixth eyepiece waveguide with multi-directional radiation 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 radiation according to an embodiment of the present invention. FIG. 11D is a simplified plan view of the user side of the sixth eyepiece waveguide with multi-directional radiation shown in FIG. 11C.

[0097]

[0184] Referring first to FIGS. 11C and 11D, this sixth eyepiece waveguide utilizes a multi-directional radiation eyepiece waveguide design, which consists of a single ICG pupil coupled to the world side of the eyepiece waveguide shown as the first ICG 1110 in FIG. 11C, which is utilized together with a second ICG 1111 coupled to the user side of the eyepiece waveguide as shown in FIG. 11D. Therefore, light from the projector is coupled into the eyepiece waveguide using these two ICGs. In the illustrated embodiment, both ICGs are disposed at the same position within the x-y plane, and all wavelengths (e.g., red wavelength, green wavelength, and blue wavelength) are radiated from each ICG, and the various wavelengths are radiated in various directions.

[0098]

[0185] In one embodiment, the first ICG 1110 and the second ICG 1111 each have lattice vectors k H and k LIt is implemented as a two-dimensional diffraction structure (e.g., two-dimensional lattice, nanostructure, etc.) that emits light in two directions represented by H ). In another embodiment, the first ICG 1110 emits light in a first direction (e.g., k L ), and the second ICG 1111 emits light in a second direction (e.g., k

[0099]

[0186] Referring to FIG. 11A, the lattice vector k H represents diffraction due to a large distance (High) in k-space, and the lattice vector k L represents diffraction due to a small distance (Low) in k-space. Thus, 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 couple light at a plurality of wavelengths and in a first direction range (corresponding to the lattice vector k H ) to generate a red FOV 1120, a green FOV 1122, and a blue FOV 1124, and couple light at a plurality of wavelengths and in a second direction range (corresponding to the lattice vector k L ) to generate a red FOV 1121, a green FOV 1123, and a blue FOV 1125 (to the extent that some or all of these FOVs are supported by the eyepiece waveguide). Referring to FIG. 11A, the blue FOV 1125, the green FOV 1123, the green FOV 1122, and the red FOV 1120 are disposed within an annular region between r = n = 1 and r = n = 2. The red FOV 1121 and the blue FOV 1124 include portions disposed within the annular region between r = n = 1 and r = n = 2. Note that a change in the refractive index of the eyepiece waveguide material (e.g., refractive index 2.5) will vary the amount of FOV included in the annular region.

[0100]

[0187] Referring to FIG. 11B, the light present in the red FOV 1120, green FOV 1122, and blue FOV 1124 is diffracted in region 1152 of the CPE 1150 coupled to the user side, hits the grating corresponding to the grating vector k2, and thereby diffracts in the plane of the eyepiece waveguide. As a result, the red FOV 1120 is shifted to the red FOV 1131 in k-space, the green FOV 1122 is shifted to the green FOV 1133 in k-space, and the blue FOV 1124 is shifted to the blue FOV 1135 in k-space. Diffraction in region 1142 of the CPE 1140 from the grating corresponding to the grating vector k3 results in out-coupling from the eyepiece waveguide. The light present in the red FOV 1121, green FOV 1123, and blue FOV 1125 is diffracted in regions 1144 of the CPE 1140 coupled to the world side and region 1154 of the CPE 1150 coupled to the user side, hits the grating corresponding to the grating vector k1, and thereby diffracts in the plane of the eyepiece waveguide. As a result, the red FOV 1121 is shifted to the red FOV 1130 in k-space, the green FOV 1123 is shifted to the green FOV 1132 in k-space, and the blue FOV 1125 is shifted to the blue FOV 1134 in k-space. Diffraction in region 1152 of the CPE 1150 from the grating corresponding to the grating vector k2 results in out-coupling from the eyepiece waveguide.

[0101]

[0188] Thus, the diffraction paths of the red, green, and blue wavelengths in-coupled by the first ICG 1110 and the second ICG 1111 in the direction represented by the grating vector k, showing the minimum sequence of interactions with various grating types when the incident light propagates from the projector to the user's eye L are k L →k1→k2. The diffraction paths of the red, green, and blue wavelengths in-coupled by the first ICG 1110 and the second ICG 1111 in the direction represented by the grating vector k H are k H →k2→k3.

[0102]

[0189] FIG. 12A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a seventh IOL waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 12B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a seventh IOL waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 12C is a simplified plan view of the world side of a seventh IOL waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 12D is a simplified plan view of the user side of the seventh IOL waveguide with multi-directional radiation shown in FIG. 12C.

[0103]

[0190] Referring first to FIGS. 12C and 12D, this seventh IOL waveguide utilizes a multi-directional radiation IOL waveguide design, which involves separate ICG pupils coupled to the world side of the IOL waveguide shown as red ICG 1210, green ICG 1212, and blue ICG 1214 in FIG. 12C, and red ICG 1211, green ICG 1213, and blue ICG 1215 coupled to the user side of the IOL waveguide as shown in FIG. 12D. Thus, light from the projector is coupled into the IOL waveguide using these six ICGs. However, as will be fully explained below, the lattice periods and corresponding lattice vectors of the various ICGs designed for the green wavelength are equal for blue light (and blue ICG) compared to red light and green light (and red ICG and green ICG). The embodiment shown in FIG. 12D includes red ICG 1211, green ICG 1213, and blue ICG 1215 coupled to the user side of the IOL waveguide, but this is not essential, and in some embodiments, red ICG 1211, green ICG 1213, and blue ICG 1215 are optional.

[0104]

[0191] Referring to FIG. 12A, the lattice vector k H represents diffraction by a first distance in k-space, and the lattice vector k Lrepresents diffraction by a second distance in the k-space. Therefore, in the case of the red ICG1210 and green ICG1212 coupled to the world side of the eyepiece waveguide, or the red ICG1211 and green ICG1213 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide as represented by the lattice vector k L to generate a red FOV1230 for the red wavelength and a green FOV1232 for the green wavelength. Both of these FOVs are arranged within the annular region between r = n = 1 and r = n = 2. The light diffracted into the eyepiece waveguide using the blue ICG1214 coupled to the world side of the eyepiece waveguide or the blue ICG1215 coupled to the user side of the eyepiece waveguide is diffracted as represented by k H . Therefore, in the case of the blue ICG1214 coupled to the world side of the eyepiece waveguide and the blue ICG1215 coupled to the user side, the light at the center of the FOV is diffracted into the eyepiece waveguide to generate a blue FOV1234 for the blue wavelength. This FOV is arranged within the annular region between r = n = 1 and r = n = 2. Therefore, since the respective barrel-shaped boxes corresponding to the red FOV1230, green FOV1232, and blue FOV1234, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 30°×30° FOV.

[0105]

[0192] Referring to FIG. 12C, the grating directions in red ICG 1210 and green ICG 1212, as well as in red ICG 1211 and green ICG 1213, are oriented such that red light and green light are radiated into the eyepiece waveguide toward region 1242 of CPE 1240 on the world side and toward region 1252 of CPE 1250 on the user side. The grating directions in blue ICG 1214 and blue ICG 1215 are oriented such that blue light is radiated into the eyepiece waveguide toward region 1246 of CPE 1240 on the world side and toward region 1256 of CPE 1250 on the user side. Regions 1242, 1246, 1252, and 1256 have a grating corresponding to lattice vector k1 as compared to the eyepiece waveguide layout shown in FIGS. 10C and 10D. Region 1244 having a grating corresponding to lattice vector k3 is disposed between region 1242 and region 1246, and region 1254 having a grating corresponding to lattice vector k2 is disposed between region 1252 and region 1256.

[0106]

[0193] Referring to FIGS. 12B and 12D, the red and green light radiated toward the region 1242 of the CPE 1240 and the region 1252 of the CPE 1250 hits the lattice corresponding to the lattice vector k1, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 1230 is shifted to the red FOV 1231 in k-space, and the green FOV 1232 is shifted to the green FOV 1233 in k-space. The diffraction in the region 1244 of the CPE 1240 from the lattice corresponding to the lattice vector k3 results in out-coupling from the eyepiece waveguide. The blue light radiated toward the region 1246 in the CPE 1240 and the region 1256 in the CPE 1250 hits the lattice corresponding to the lattice vector k1 in the regions 1246 and 1256, thereby diffracting in the plane of the eyepiece waveguide. As a result, the blue FOV 1234 is shifted to the blue FOV 1235 in k-space. The diffraction in the region 1254 of the CPE 1250 from the lattice corresponding to the lattice vector k2 results in out-coupling from the eyepiece waveguide. Thus, the diffraction paths of the red and green wavelengths showing the minimum sequence of interaction with various lattice types when the incident light propagates from the projector to the user's eye are k L →k1→k3. The diffraction path of the blue wavelength is k H →k1→k2.

[0107]

[0194] FIG. 13A is a simplified k-space diagram showing the field of view and ICG lattice vectors of an eighth eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 13B is a simplified k-space diagram showing the field of view and CPE lattice vectors of an eighth eyepiece waveguide with multi-directional radiation 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 radiation according to an embodiment of the present invention. FIG. 13D is a simplified plan view of the user side of the eighth eyepiece waveguide with multi-directional radiation shown in FIG. 13C.

[0108]

[0195] Referring initially to FIGS. 13C and 13D, this eighth IPE waveguide utilizes a multi-directional radiation IPE waveguide design, which involves a single ICG pupil coupled to the world side of the IPE waveguide shown as the first ICG1310 in FIG. 13C and utilized with a second ICG1311 coupled to the user side of the IPE waveguide as shown in FIG. 13D. Thus, light from the projector is coupled into the IPE waveguide using these two ICGs. In the illustrated embodiment, both ICGs are disposed at the same position within the x - y plane, and all wavelengths (e.g., red wavelength, green wavelength, and blue wavelength) are radiated from each ICG, with the various wavelengths being radiated in various directions. Regions 1342, 1346, 1352, and 1356 have a lattice corresponding to the lattice vector k1, similar to the IPE waveguide layout shown in FIGS. 12C and 12D. Region 1344 having a lattice corresponding to the lattice vector k3 is disposed between region 1342 and region 1346, and region 1354 having a lattice corresponding to the lattice vector k2 is disposed between region 1352 and region 1356.

[0109]

[0196] In one embodiment, the first ICG1310 and the second ICG1311 are each implemented as a two - dimensional diffraction structure (e.g., two - dimensional lattice, nanostructure, etc.) that emits light in two directions represented by the lattice vectors k H and k L . In another embodiment, the first ICG1310 emits light in a first direction (e.g., k H ), and the second ICG1311 emits light in a second direction (e.g., k L ). The single ICG design is particularly suitable for use in micro - LED displays where the primary colors cannot be easily spatially separated. Thus, light from the micro - LED display can be imaged onto a single ICG.

[0110]

[0197] Referring to FIG. 13A, the lattice vector k H represents diffraction by a first distance within k - space, and the lattice vector k Lrepresents diffraction by a second distance in the k-space. Thus, the first ICG1310 coupled to the world side of the eyepiece waveguide and the second ICG1311 coupled to the user side of the eyepiece waveguide couple light at a plurality of wavelengths and a first direction range (corresponding to the lattice vector k H ), generate a red FOV1320, a green FOV1322, and a blue FOV1324, and couple light at a plurality of wavelengths and a second direction range (corresponding to the lattice vector k L ), generating a red FOV1321, a green FOV1323, and a blue FOV1325 (to the extent that some or all of these FOVs are supported by the eyepiece waveguide). Referring to FIG. 13A, the blue FOV1325, the green FOV1323, the green FOV1322, and the red FOV1320 are disposed within the annular region between r = n = 1 and r = n = 2. The red FOV1321 and the blue FOV1324 include portions disposed within the annular region between r = n = 1 and r = n = 2. Note that the change in the refractive index of the eyepiece waveguide material (e.g., refractive index 2.5) will vary with the amount of FOV included in the annular region.

[0111]

[0198] Referring to FIG. 13B, the light present in the red FOV 1320, green FOV 1322, and blue FOV 1324 is diffracted in the regions 1342 of the CPE 1340 coupled to the world side and the regions 1352 of the CPE 1350 coupled to the user side, hits 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 shifted to the red FOV 1321 in k-space, the green FOV 1322 is shifted to the green FOV 1323 in k-space, and the blue FOV 1324 is shifted 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 out-coupling from the eyepiece waveguide. The light present in the red FOV 1321, green FOV 1323, and blue FOV 1325 is diffracted in the regions 1346 of the CPE 1340 coupled to the world side and the regions 1356 of the CPE 1350 coupled to the user side, hits 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 shifted to the red FOV 1320 in k-space, the green FOV 1323 is shifted to the green FOV 1322 in k-space, and the blue FOV 1325 is shifted to the blue FOV 1324 in k-space. Diffraction in the region 1354 of the CPE 1350 from the grating corresponding to the grating vector k2 results in out-coupling from the eyepiece waveguide.

[0112]

[0199] Thus, the diffraction paths of the red, green, and blue wavelengths in-coupled by the first ICG 1310 and the second ICG 1311 in the direction represented by the grating vector k, which shows the minimum sequence of interactions with various grating types when the incident light propagates from the projector to the user's eye, are H k H →k1→k2. The diffraction paths of the red, green, and blue wavelengths in-coupled by the first ICG 1310 and the second ICG 1311 in the direction represented by the grating vector k are L k L →k1→k3.

[0113]

[0200] FIG. 14A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a first eyepiece waveguide including a two-dimensional lattice with multi-directional radiation, according to an embodiment of the present invention. FIG. 14B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a first eyepiece waveguide including a two-dimensional lattice with multi-directional radiation, 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 lattice with multi-directional radiation, according to an embodiment of the present invention. FIG. 14D is a simplified plan view of the user side of the first eyepiece waveguide including the two-dimensional lattice with multi-directional radiation shown in FIG. 14C.

[0114]

[0201] Referring first to FIGS. 14C and 14D, this first eyepiece waveguide utilizes a multi-directional radiation eyepiece waveguide design, which includes separate ICG pupils coupled to the world side of the eyepiece waveguide shown as red ICG 1410, green ICG 1412, and blue ICG 1414 in FIG. 14C, and is utilized with the red ICG 1411, green ICG 1413, and blue ICG 1415 coupled to the user side of the eyepiece waveguide as shown in FIG. 14D. Thus, light from the projector is coupled to the eyepiece waveguide using these six ICGs. However, as will be fully explained below, the lattice periods and corresponding lattice vectors of the various ICGs designed for the green wavelength are equal for blue light (and the blue ICG) as compared to red light and green light (and the red ICG and green ICG). The embodiment shown in FIG. 14D includes red ICG 1411, green ICG 1413, and blue ICG 1415 coupled to the user side of the eyepiece waveguide, but this is not essential, and in some embodiments, red ICG 1411, green ICG 1413, and blue ICG 1415 are optional.

[0115]

[0202] Referring to FIG. 14A, the lattice vector k H represents diffraction by a first distance in k-space, and the lattice vector k Lrepresents diffraction by the second distance in k-space. Therefore, in the case of the red ICG1410 and green ICG1412 coupled to the world side of the eyepiece waveguide, or the red ICG1411 and green ICG1413 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide as represented by the lattice vector k L to generate a red FOV1430 for the red wavelength and a green FOV1432 for the green wavelength. Both of these FOVs are arranged within the annular region between r = n = 1 and r = n = 2. The light diffracted into the eyepiece waveguide using the blue ICG1414 coupled to the world side of the eyepiece waveguide or the blue ICG1415 coupled to the user side of the eyepiece waveguide is diffracted as represented by k H . Therefore, in the case of the blue ICG1414 coupled to the world side of the eyepiece waveguide and the blue ICG1415 coupled to the user side, the light at the center of the FOV is diffracted into the eyepiece waveguide to generate a blue FOV1434 for the blue wavelength. This FOV is arranged within the annular region between r = n = 1 and r = n = 2. Therefore, since the respective frustum-shaped boxes corresponding to the red FOV1430, green FOV1432, and blue FOV1434, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 30° × 30° FOV.

[0116]

[0203] Referring to FIG. 14C, the directions of the gratings in the red ICG 1410 and green ICG 1412, and the red ICG 1411 and green ICG 1413 are oriented such that red and green light is radiated into the eyepiece waveguide towards the region 1442 of the CPE 1440 on the world side and towards the region 1452 of the CPE 1450 on the user side. The directions of the gratings in the blue ICG 1414 and blue ICG 1415 are oriented such that blue light is radiated into the eyepiece waveguide towards the region 1444 of the CPE 1440 on the world side and towards the region 1454 of the CPE 1450 on the user side. Regions 1444 and 1454 have a grating corresponding to the lattice vector k1. Region 1442 having a grating corresponding to the lattice vector k3 is disposed adjacent to region 1444. Region 1452 having a two-dimensional grating corresponding to the lattice vectors k 2a and k 2b is disposed adjacent to region 1454.

[0117]

[0204] Referring to FIGS. 14B and 14D, the red and green light radiated towards the region 1442 of the CPE 1440 hits the grating corresponding to the lattice vector k3, and the red and green light radiated towards the region 1452 of the CPE 1450 hits the two-dimensional grating characterized by the lattice vector k 2a in the first direction and the lattice vector k 2b orthogonal thereto in the second direction. Diffraction corresponding to the lattice vectors k3, k 2a , k 2b results in diffraction in the plane of the eyepiece waveguide. As a result, in response to diffraction corresponding to the lattice vector k 2a , the red FOV 1430 shifts to the red FOV 1431 in k-space and the green FOV 1432 shifts to the green FOV 1433 in k-space, and in response to diffraction corresponding to the lattice vector k 2b , the red FOV 1430 shifts to the red FOV 1437 in k-space and the green FOV 1432 shifts to the green FOV 1439 in k-space. Diffraction in the region 1444 of the CPE 1440 from the grating corresponding to the lattice vector k3 results in out-coupling from the eyepiece waveguide.

[0118]

[0205] The blue light radiated towards regions 1444 within CPE 1440 and 1454 within CPE 1450 hits the gratings corresponding to the lattice vector k1 within regions 1444 and 1454, thereby diffracting in the plane of the eyepiece waveguide. As a result, the blue FOV 1434 shifts to the blue FOV 1435 in k-space. The diffraction in region 1444 of CPE 1440 from the grating corresponding to the lattice vector k 2a results in out-coupling from the eyepiece waveguide. Thus, the diffraction paths of the red and green wavelengths showing the minimum sequence of interactions with various grating types when the incident light propagates from the projector to the user's eye are k L →k 2a / k 2b →k3. The diffraction path of the blue wavelength is k H →k1→k 2a / k.

[0119]

[0206] FIG. 15A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a first eyepiece waveguide including a two-dimensional grating with multi-directional radiation according to an embodiment of the present invention. FIG. 15B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a first eyepiece waveguide including a two-dimensional grating with multi-directional radiation 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 radiation according to an embodiment of the present invention. FIG. 15D is a simplified plan view of the user side of the first eyepiece waveguide including the two-dimensional grating with multi-directional radiation shown in FIG. 15C.

[0120]

[0207] Referring initially to FIGS. 15C and 15D, this first IPE waveguide utilizes a multi-directional radiation IPE waveguide design, which uses separate ICG pupils coupled to the world side of the IPE waveguide shown as red ICG1510, green ICG1512, and blue ICG1514 in FIG. 15C, along with red ICG1511, green ICG1513, and blue ICG1515 coupled to the user side of the IPE waveguide as shown in FIG. 15D. Thus, light from the projector is coupled into the IPE waveguide using these six ICGs. However, as will be fully explained below, the grating periods and corresponding grating vectors of the various ICGs designed for the green wavelength are equal for blue light (and blue ICG) compared to red light and green light (and red ICG and green ICG). The embodiment shown in FIG. 15D includes red ICG1511, green ICG1513, and blue ICG1515 coupled to the user side of the IPE waveguide, but this is not essential, and in some embodiments, red ICG1511, green ICG1513, and blue ICG1515 are optional.

[0121]

[0208] Referring to FIG. 15A, the grating vector k H represents diffraction by a first distance in k-space, and the grating vector k L represents diffraction by a second distance in k-space. Thus, for the red ICG1510 and green ICG1512 coupled to the world side of the IPE waveguide, or the red ICG1511 and green ICG1513 coupled to the user side of the IPE waveguide, the light at the center of the FOV is diffracted into the IPE waveguide as represented by the grating vector k L to generate a red FOV1530 for the red wavelength and a green FOV1532 for the green wavelength. Both of these FOVs are disposed within the annular region between r = n = 1 and r = n = 2. The light diffracted into the IPE waveguide using the blue ICG1514 coupled to the world side of the IPE waveguide, or the blue ICG1515 coupled to the user side of the IPE waveguide, is k HDiffracts as represented by. Thus, in the case of blue ICG1514 coupled to the world side of the eyepiece waveguide and blue ICG1515 coupled to the user side, the light at the center of the FOV is diffracted within the eyepiece waveguide to generate a blue FOV1534 for the blue wavelength. This FOV is disposed within the annular region between r = n = 1 and r = n = 2. Thus, since the respective barrel-shaped boxes corresponding to the red FOV1530, green FOV1532, and blue FOV1534, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 30° × 30° FOV.

[0122]

[0209] Referring to FIG. 15C, the grating directions in red ICG1510 and green ICG1512, and red ICG1511 and green ICG1513 are oriented such that red light and green light are radiated into the eyepiece waveguide toward the upper left portion of the CPE1540 on the world side and toward the upper left portion of the CPE1550 on the user side. The grating directions in blue ICG1514 and blue ICG1515 are oriented such that blue light is radiated into the eyepiece waveguide toward the lower right portion of the CPE1540 on the world side and toward the lower right portion of the CPE1550 on the user side. The CPE1540 has a grating corresponding to the lattice vectors k2 and k3 over the entire CPE. The CPE1550 has a grating corresponding to the lattice vectors k1 and k2 over the entire CPE.

[0123]

[0210] Referring to FIGS. 15B and 15D, the red light and green light radiated towards the upper left part of the CPE 1540 hit the components of the two-dimensional lattice corresponding to the lattice vector k2, and the red light and green light radiated towards the upper left part of the CPE 1550 hit the components of the two-dimensional lattice corresponding to the lattice vector k2. The diffraction corresponding to the lattice vector k2 results in diffraction within the plane of the eyepiece waveguide. As a result, in response to the diffraction corresponding to the lattice vector k2, the red FOV 1530 shifts to the red FOV 1531 in k-space, and the green FOV 1532 shifts to the green FOV 1533 in k-space. The diffraction in the CPE 1540 from the lattice corresponding to the lattice vector k3 results in out-coupling from the eyepiece waveguide.

[0124]

[0211] The blue light radiated towards the lower right part of the CPE 1550 hits the components of the two-dimensional lattice corresponding to the lattice vector k1, thereby diffracting within the plane of the eyepiece waveguide. As a result, the blue FOV 1534 shifts to the blue FOV 1535 in k-space. The diffraction in the CPE 1540 and CPE 1550 from the components of the two-dimensional lattice corresponding to the lattice vector k2 results in out-coupling from the eyepiece waveguide. Therefore, the diffraction paths of the red and green wavelengths showing the minimum sequence of interactions with various lattice types when the incident light propagates from the projector to the user's eye are k L →k2→k3. The diffraction path of the blue wavelength is k H →k1→k2.

[0125]

[0212] As described in connection with FIG. 3D, the diffraction structures shown in FIGS. 15C and 15D as being manufactured on the world side and the user side can be implemented on the opposing sides or in a single-sided design. As an example, the lattices corresponding to the lattice vector k1, the lattice vector k2, and the lattice vector k3 shown in FIGS. 15C and 15D can be implemented as a single-sided design in which all the lattices are coupled to one side of the eyepiece waveguide. Therefore, the functions described in connection with FIGS. 15C and 15D can be implemented using a single-sided design.

[0126]

[0213] FIG. 16A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a wide-field eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 16B is a simplified k-space diagram showing the field of view and CPE lattice vectors of a wide-field eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 16C is a simplified plan view of the world side of a wide-field eyepiece waveguide with multi-directional radiation according to an embodiment of the present invention. FIG. 16D is a simplified plan view of the user side of the wide-field eyepiece waveguide with multi-directional radiation shown in FIG. 16C.

[0127]

[0214] The designs shown in FIGS. 16A-16D correspond to the designs shown in FIGS. 8A-8D and have the modification that the fields of view shown in FIGS. 16A and 16B are wider in the horizontal direction than the fields of view shown in FIGS. 8A and 8B.

[0128]

[0215] Referring first to FIGS. 16C and 16D, this wide-field eyepiece waveguide utilizes a multi-directional radiation eyepiece waveguide design, which uses separate ICG pupils coupled to the world side of the eyepiece waveguide shown as red ICG 1610, green ICG 1612, and blue ICG 1614 in FIG. 16C, along with red ICG 1611, green ICG 1613, and blue ICG 1615 coupled to the user side of the eyepiece waveguide as shown in FIG. 16D. Thus, light from the projector is coupled into the eyepiece waveguide using these six ICGs. However, as will be fully explained below, the lattice periods and corresponding lattice vectors of the various ICGs designed for the green wavelength are different for blue light (and blue ICG) compared to red and green light (and red and green ICG). The embodiment shown in FIG. 16D includes red ICG 1611, green ICG 1613, and blue ICG 1615 coupled to the user side of the eyepiece waveguide, but this is not essential and in some embodiments, red ICG 1611, green ICG 1613, and blue ICG 1615 are optional.

[0129]

[0216] Referring to FIG. 16A, the lattice vector k Hrepresents diffraction due to a large distance (High) in k-space, and the lattice vector k L represents diffraction due to a small distance (Low) in k-space. Therefore, the lattice corresponding to the lattice vector k L is characterized by the same lattice dimension (i.e., the same lattice period, e.g., 525 nm / ~1.5≒350 nm), while the lattice corresponding to the lattice vector k H is characterized by a large lattice dimension (i.e., a small lattice period, e.g., 525 nm / ~1.9≒276 nm). Therefore, in the case of the red ICG1610 and green ICG1612 coupled to the world side of the eyepiece waveguide, or the red ICG1611 and green ICG1613 coupled to the user side of the eyepiece waveguide, the light at the center of the FOV is diffracted into the eyepiece waveguide as represented by the lattice vector k L to generate a red FOV1630 for the red wavelength and a green FOV1632 for the green wavelength. Both of these FOVs are arranged within the annular region between r = n = 1 and r = n = 2 despite their large horizontal widths. The light diffracted into the eyepiece waveguide using the blue ICG1614 coupled to the world side of the eyepiece waveguide or the blue ICG1615 coupled to the user side of the eyepiece waveguide is diffracted as represented by k H . Therefore, in the case of the blue ICG1614 coupled to the world side of the eyepiece waveguide and the blue ICG1615 coupled to the user side, the light at the center of the FOV is diffracted into the eyepiece waveguide to generate a blue FOV1634 for the blue wavelength. This FOV is arranged within the annular region between r = n = 1 and r = n = 2 despite its large horizontal width. Therefore, since the respective wide fields of view corresponding to the red FOV1630, green FOV1632, and blue FOV1634, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 40°×30° FOV.

[0130]

[0217] Referring to FIG. 16C, the directions of the gratings in the red ICG 1610 and green ICG 1612, as well as in the red ICG 1611 and green ICG 1613, are oriented such that red light and green light are radiated into the eyepiece waveguide towards the region 1642 of the CPE 1640 on the world side and towards the region 1652 of the CPE 1650 on the user side. The directions of the gratings in the blue ICG 1611 and blue ICG 1620 are oriented such that blue light is radiated into the eyepiece waveguide towards the region 1644 of the CPE 1640 on the world side and towards the region 1654 of the CPE 1650 on the user side.

[0131]

[0218] Referring to FIGS. 16B and 16D, the red light and green light radiated towards the region 1652 of the CPE 1650 strike the grating corresponding to the lattice vector k2, thereby diffracting in the plane of the eyepiece waveguide. As a result, the red FOV 1630 is shifted to the red FOV 1631 in k-space, and the green FOV 1632 is shifted to the green FOV 1633 in k-space. Diffraction in the region 1642 from the grating corresponding to the lattice vector k3 results in out-coupling from the eyepiece waveguide. The blue light radiated towards the region 1644 within the CPE 1640 and the region 1654 within the CPE 1650 strikes the grating corresponding to the lattice vector k1 within the regions 1644 and 1654, thereby diffracting in the plane of the eyepiece waveguide. As a result, the blue FOV 1634 is shifted to the blue FOV 1635 in k-space. Diffraction in the region 1652 from the grating corresponding to the lattice vector k2 results in out-coupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths showing the minimum sequence of interactions with the various grating types when the incident light propagates from the projector to the user's eye are k L →k2→k3. The diffraction path for the blue wavelength is k H →k1→k2.

[0132]

[0219] As shown in FIGS. 16A and 16B, the red FOVs 1630 / 1631, green FOVs 1632 / 1633, and blue FOVs 1634 / 1635 are all arranged within the annular region between r = n = 1 and r = n = 2, despite their wide horizontal widths. Thus, propagation and out-coupling within the plane of the eyepiece waveguide are performed without clipping of the FOV.

[0133]

[0220] The inventors have revealed that the multi-directional radiation waveguide design described herein is particularly useful for an AR display design in which the projector is located near the upper right corner of the eyepiece. Geometric arrangements such as various grating regions, gradient zones, grating parameters, materials, ICGs, and projector arrangements can be varied 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 desired uniformity and efficiency of the AR display.

[0134]

[0221] In the embodiments shown in FIGS. 7C / 7D, 9C / 9D, 11C / 11D, and 13C / 13D, a multi-directional radiation waveguide design is shown that uses a single ICG pupil to radiate light of all three primary colors (i.e., red wavelength light, green wavelength light, and blue wavelength light) into the eyepiece waveguide. Some designs that can be used to achieve this multi-directional radiation are described below.

[0135]

[0222] FIG. 17A is a schematic cross-sectional view showing an eyepiece waveguide having bilateral ICGs according to an embodiment of the present invention. In FIG. 17A, an 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 surface 1701 of the eyepiece waveguide 1700. A second ICG 1712 operating in a reflection mode is coupled to a second side surface 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 a CPE 1720, which diffracts light in the plane of the eyepiece waveguide and out-couples light from the eyepiece waveguide toward the user.

[0136]

[0223] FIG. 17B is an exploded plan view showing the bilateral ICGs shown in FIG. 17A. As shown in FIG. 17A, incident light is diffracted by an ICG 1710 operating in a transmission mode. The grating of the ICG 1710 is defined by a grating vector k L as described above. The incident light that has passed through the eyepiece waveguide 1700 is diffracted by an ICG 1712 operating in a reflection mode. The grating of the ICG 1712 is defined by a grating vector k H as described above. Thus, in this embodiment, one-dimensional ICG gratings coupled to both sides of the eyepiece, each having a different grating vector (i.e., grating period), are utilized to realize a combined two-dimensional diffraction structure.

[0137]

[0224] FIG. 17C is a schematic cross-sectional view showing a metallized blazed grating according to an embodiment of the present invention. FIG. 17D is a schematic cross-sectional view showing a coated blazed grating according to an embodiment of the present invention. FIG. 17E is a schematic cross-sectional view showing a coated tilted grating according to an embodiment of the present invention. FIG. 17F is a schematic cross-sectional view showing a coated blazed grating according to an embodiment of the present invention.

[0138]

[0225] As shown in FIGS. 17B to 17F, the 1D ICG can have various coatings deposited on the lattice structure and can have various shapes including inclined and blazed type gratings with one or more coating layers as needed. Also, meta-structures including holes / pillars, multi-level structures, and discontinuous structures can be used. The ICG functioning in the reflection mode can be covered with a highly reflective metal such as aluminum or silver, thereby improving the overall efficiency of radiating light into the eyepiece waveguide. Therefore, embodiments of the present invention can utilize gratings including inclined structures, sawtooth structures, and / or multi-level structures, etc. to improve the directivity towards the user. Further, the gratings described herein can be biased with an overcoat formed on the lattice structure within the ICG or CPE, for example, TiO2.

[0139]

[0226] In addition to imprinting the diffraction structure into the polymer resin, the polymer resin can have a refractive index in the range of, for example, 1.5 to 2.0 as will be fully described below. Embodiments of the present invention can utilize diffraction structures etched into high refractive index materials including, for example, Si3N4, ZrO2, TiO2, LiNbO3, LiTaO3, SiC, etc., which can be referred to as a support structure or used as a substrate for an eyepiece waveguide, and can be deposited as a film on a substrate. Dry etching processes such as reactive ion etching (RIE), inductively coupled plasma - reactive ion etching (ICP - RIE), ion beam etching (IBE), etc. can be used to etch the diffraction structure, and various gases including CF4, C2F8, CHF3, SF6, O2, Ar, He, BCl3, Cl2, etc. can be utilized. The diffraction structure can also be formed in one or more overcoat films (for example, MgF2, SiO2, Si3N4, ZrO2, TiO2, SiC, etc. which can have a refractive index in the range of 1.3 to 2.6) deposited on an imprinted polymer (for example, a polymer resin having a refractive index of 1.5 to 2.0 and an imprinted diffraction pattern). In addition to imprinting and etching, the diffraction pattern can be formed by molding a substrate, for example, a polymer having 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 increase the diffraction efficiency of TIR light, reduce external light reflection, or both.

[0140]

[0227] In connection with imprinting a polymer resin with a diffraction structure, an imprintable prepolymer material can include a resin material such as an epoxy vinyl ester. The resin can include vinyl monomers (e.g., methyl methacrylate) and / or difunctional or trifunctional vinyl monomers (e.g., diacrylate, triacrylate, dimethacrylate, etc.), regardless of the presence or absence of aromatic molecules in the monomer. The prepolymer material can include monomers having one or more functional groups such as alkyl, carboxyl, carbonyl, hydroxyl, and / or alkoxy. Both sulfur atoms having a high polarizability and aromatic groups can be incorporated into these acrylate components to increase the refractive index of the formulation, generally to an index in the range of 1.5 to 1.75. In some embodiments, the prepolymer material can include a cycloaliphatic epoxy containing a resin that can be cured using ultraviolet light and / or heat. Further, the prepolymer material can include an ultraviolet cationic photoinitiator and a co-reactant to facilitate efficient ultraviolet curing under ambient conditions.

[0141]

[0228] By incorporating inorganic nanoparticles (NPs) such as ZrO2 and TiO2 into such imprintable resin polymers, the refractive index can be significantly increased, for example, up to n = 2.1. Furthermore, the use of pure ZrO2 and TiO2 crystals can result in refractive indices of n = 2.2 and n = 2.4 - 2.6, respectively, at 532 nm. To prepare optical nanocomposites of acrylate monomers and inorganic nanoparticles, the particle size is generally less than 10 nm to avoid excessive Rayleigh scattering. Due to its high specific surface area, high polarity, and incompatibility with the cross-linked polymer matrix, ZrO2 NPs tend to aggregate in the polymer matrix. To overcome this problem, surface modification of the NPs can be used. In this technique, the hydrophilic surface of ZrO2 is modified to be compatible with organic substances, and thus the NPs can be uniformly mixed with the polymer. Such modification can be carried out using silane and carboxylic acid-containing capping agents. One end of the capping agent binds to the ZrO2 surface, while the other end of the capping agent contains either a functional group that can participate in acrylate cross-linking or a non-functional organic moiety. Examples of surface-modified sub-10 nm ZrO2 particles are those supplied by Pixelligent Technologies (trademark) and Cerion Advanced Materials (trademark). These functionalized nanoparticles are usually sold as a uniform blend suspended uniformly in a solvent, and in combination with other bases, a resist formulation with a printable viscosity and an increased refractive index can be obtained.

[0142]

[0229] Crosslinking and patterning using the diffraction pattern involves contacting the prepolymer with a template (e.g., in the case of imprint lithography, e.g., J-FIL (trademark) where the prepolymer material is dispensed using inkjet), and the prepolymer is exposed to a wavelength between 310 nm and 410 nm and 0.1 J / cm 2 ~100 J / cm 2It can be achieved by exposing to actinic rays having an intensity therebetween. This method can further include heating while exposing the prepolymer to actinic rays so that the temperature of the prepolymer becomes 40°C to 120°C.

[0143]

[0230] Figures 18A to 18D show 2D ICGs coupled to one side of the eyepiece waveguide. Each of these 2D ICGs has a grating vector that diffracts light two-dimensionally to implement a multi-directional radiation design.

[0144]

[0231] Figure 18A is a perspective view of a 2D ICG according to an embodiment of the present invention. In Figure 18A, rows of a blazed grating structure are shown. As shown by the variation in height of each row in the column direction, each row in the column direction is also blazed. Thus, a 2D grating structure suitable for use in the embodiments described herein is provided.

[0145]

[0232] Figure 18B is a perspective view of a 2D ICG according to another embodiment of the present invention. In Figure 18B, pillars arranged in rows and columns are shown. In the illustrated embodiment, one or more sides of the pillars are inclined, but this is not essential.

[0146]

[0233] Figure 18C is a perspective view of a 2D ICG according to a third embodiment of the present invention. In Figure 18C, pyramid-shaped elements arranged in rows and columns are shown. In the illustrated embodiment, the pyramid-shaped elements are joined at the base of each element, but this is not essential, and in other embodiments, the pyramid-shaped elements are separated from each other by a gap.

[0147]

[0234] FIG. 18D is a perspective view of a two-dimensional ICG according to a fourth embodiment of the present invention. In FIG. 18D, pillars arranged in rows and columns are shown. In the illustrated embodiment, the pillar has a stepped structure having a base and a protrusion extending from the base. The stepped structure shown in FIG. 18D utilizes two steps, namely the base and the protrusion, but embodiments of the present invention are not limited to these two stepped structures, and stepped structures having additional steps are included within the scope of the embodiments described herein. Further, in the present embodiment, the sides of the structure are parallel to each other, but the sides can also be inclined according to specific applications. Those skilled in the art will recognize many variations, modifications, and alternative forms.

[0148]

[0235] The multi-directional emission design described herein emits blue light in a direction different from the direction used to emit red light and green light. Other embodiments can emit blue light and green light along the same direction and red light along a separate different direction. These other embodiments are not shown herein but are included within the scope of the present invention.

[0149]

[0236] In the case of a multi-directional emission design in which red light and green light are emitted along the same direction, the same ICG design (e.g., pitch and grating direction) may be utilized. Thus, while many of the multi-directional emission designs described herein utilize three separate ICGs for red light, green light, and blue light, it is possible to use the same ICG for red light and green light. Such embodiments are shown in FIGS. 19A - 19C.

[0150]

[0237] FIG. 19A is a simplified k-space diagram showing the field of view and ICG lattice vectors of a third IOL 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 IOL waveguide with multi-directional emission according to an embodiment of the present invention. FIG. 19C is a simplified plan view of the user side of the third IOL waveguide with multi-directional emission shown in FIG. 19B.

[0151]

[0238] Referring initially to FIGS. 19B and 19C, this IPE waveguide utilizes a multi-directional radiation IPE waveguide design, which uses separate ICG pupils coupled to the world side of the IPE waveguide, shown as red / green ICG 1910 and blue ICG 1914 in FIG. 19B, along with red / green 1911 and blue ICG 1915 coupled to the user side of the IPE waveguide as shown in FIG. 19C. Thus, light from the projector is coupled into the IPE waveguide using these four ICGs. However, as will be fully explained below, the grating periods and corresponding grating vectors of various ICGs designed for the green wavelength are equal for blue light (and blue ICG) compared to red light and green light (and red ICG and green ICG). The embodiment shown in FIG. 19C includes red / green ICG 1911 and blue ICG 1915 coupled to the user side of the IPE waveguide, but this is not essential, and in some embodiments, red / green ICG 1911 and blue ICG 1915 are optional.

[0152]

[0239] Referring to FIG. 19A, the grating vector k H represents diffraction by a first distance in k-space, and the grating vector k L represents diffraction by a second distance in k-space. Thus, for the red / green ICG 1910 coupled to the world side of the IPE waveguide, or the red / green ICG 1911 coupled to the user side of the IPE waveguide, light at the center of the FOV is diffracted into the IPE waveguide as represented by the grating vector k L to generate a red FOV 1930 for the red wavelength and a green FOV 1932 for the green wavelength. Both of these FOVs are located within an annular region between r = n = 1 and r = n = 2. Light diffracted into the IPE waveguide using the blue ICG 1914 coupled to the world side of the IPE waveguide, or the blue ICG 1915 coupled to the user side of the IPE waveguide, is k HDiffracts as represented by. Thus, in the case of the blue ICG1914 coupled to the world side of the eyepiece waveguide and the blue ICG1915 coupled to the user side, the light at the center of the FOV is diffracted within the eyepiece waveguide to generate a blue FOV1934 for the blue wavelength. This FOV is disposed within an annular region between r = n = 1 and r = n = 2. Thus, since the respective frustum-shaped boxes corresponding to the red FOV1930, the green FOV1932, and the blue FOV1934, which correspond to the TIR light, are completely within the annular region, this wavelength-specific multi-directional radiation structure enables a complete 30°×30° FOV.

[0153]

[0240] Referring to FIG. 19B, the directions of the gratings in the red / green ICG1910 and the red / green ICG1911 are oriented such that red and green light is radiated into the eyepiece waveguide toward the region 1942 of the CPE1940 on the world side and toward the region 1952 of the CPE1950 on the user side. The directions of the gratings in the blue ICG1914 and the blue ICG1915 are oriented such that blue light is radiated into the eyepiece waveguide toward the region 1944 of the CPE1940 on the world side and toward the region 1954 of the CPE1950 on the user side. Regions 1944 and 1954 have a grating corresponding to the grating vector k1. The region 1942 having a grating corresponding to the grating vector k3 is disposed adjacent to the region 1944. The region 1952 having a grating corresponding to the grating vector k2 is disposed adjacent to the region 1954.

[0154]

[0241] Referring to FIGS. 19A and 19C, the red and green light radiated toward the region 1952 of the CPE1950 strikes the grating corresponding to the grating vector k2, which results in diffraction within the plane of the eyepiece waveguide. The diffraction in the region 1942 of the CPE1940 from the grating corresponding to the grating vector k3 results in out-coupling from the eyepiece waveguide.

[0155]

[0242] The blue light radiated towards region 1944 within CPE1940 and region 1954 within CPE1950 hits the grating corresponding to lattice vector k1 within regions 1944 and 1954, thereby diffracting in the plane of the eyepiece waveguide. The diffraction in region 1952 of CPE1950 from the grating corresponding to lattice vector k2 results in out-coupling from the eyepiece waveguide. Thus, the diffraction paths for the red and green wavelengths showing the minimum sequence of interactions with various grating types when the incident light propagates from the projector to the user's eye are k L →k2→k3. The diffraction path for the blue wavelength is k H →k1→k2.

[0156]

[0243] Thus, in the embodiments shown in FIGS. 19A - 19C, two ICGs coupled to the world side and / or the user side are utilized. This embodiment, among other advantages, enables reducing the volume of the entire projector, which is an important consideration in the design of the AR headset.

[0157]

[0244] Table 2 lists the approximate (i.e., rounded) maximum values of the field of view possible with different material selections according to embodiments of the present invention. In Table 2, the materials are listed in the first column in ascending order of refractive index values for a unidirectional emission structure and for one of the multi - directional emission structures. The second column represents the best scenario of the unidirectional emission structure where the projector is horizontally aligned with the CPE center (i.e., the nominal eye position). The third and fourth columns show scenarios where the projector is positioned in the 2 o'clock and 1 o'clock directions respectively with respect to the CPE center. As shown in Table 2, for a given material selection, the multi - directional emission structure described herein provides a larger field of view than is possible with the unidirectional emission structure.

Table 2

[0158]

[0245] Figure 20A is a simplified k-space diagram showing the field of view of the eyepiece waveguide and the ICG lattice vectors according to an embodiment of the present invention. In Figure 20A, the projector is horizontally aligned with the CPE center, and lattice vector 2010 is shown in relation to the emission of light from the 3 o'clock position. The data in the second column of Table 2 corresponds to this k-space diagram.

[0159]

[0246] Figure 20B is a simplified k-space diagram showing the field of view of another eyepiece waveguide and the ICG lattice vectors according to an embodiment of the present invention. In Figure 20B, lattice vector 2020 is shown in relation to the positioning of the projector in the 2 o'clock direction with respect to the CPE center. The data in the third column of Table 2 corresponds to this k-space diagram.

[0160]

[0247] Figure 20C is a simplified k-space diagram showing the field of view of the eyepiece waveguide with multi-directional emission and the ICG lattice vectors according to an embodiment of the present invention. In Figure 20C, lattice vectors 2030 and 2032 correspond to the emission of red and green light respectively from the 3 o'clock position with respect to the CPE center. Lattice vector 2034 is shown in relation to the emission of blue light with the projector positioned in the 1 o'clock direction with respect to the CPE center. The data in the fourth column of Table 2 corresponds to this k-space diagram.

[0161]

[0248] These k-space diagrams and Table 2 show the maximum field of view possible to increase the refractive index value of the waveguide substrate using various material selections. For these k-space diagrams and Table 2, the central illumination wavelengths are 455 nm (blue), 525 nm (green), and 628 nm (red).

[0162]

[0249] The inventors have determined that the materials used in waveguides are relatively lossy or absorptive at short wavelengths, i.e., blue wavelengths as compared to red and green wavelengths. This causes efficiency problems for blue light because light that is thought to spread across a large area of the eyepiece waveguide can be absorbed before it is emitted or out-coupled towards the user. This high absorption not only reduces the efficiency of blue light, but also potentially reduces the amount of blue light emitted from the nose portion of the eyepiece (i.e., the portion furthest from the ICG / projector). This can cause problems in achieving good color uniformity in an AR display for all angles of incidence and for people with a small AR interpupillary distance (IPD).

[0163]

[0250] Accordingly, in the context of a multi-directional emission structure, when blue light diffuses and out-couples from the eyepiece, it is possible to select between various designs depending on the overall path length of the blue light. This process can be illustrated by comparing two different multi-directional emission structures as shown in FIGS. 21A / 21B and FIGS. 21C / 21D respectively.

[0164]

[0251] FIG. 21A is a simplified top view of the world side of an eyepiece waveguide with multi-directional emission where blue light is emitted in a first direction according to an embodiment of the present invention. FIG. 21B is a simplified top view of the user side of the eyepiece waveguide with multi-directional emission by the blue light emitted in the first direction shown in FIG. 21A. Referring to FIGS. 21A and 21B, blue light is emitted in the 7 o'clock direction from blue ICGs 2114 and 2115 and hits regions 2144 of CPE 2140 coupled to the world side and regions 2154 of CPE 2150 coupled to the user side. The total path lengths from ICGs 2114 and 2115 to the respective centers of CPEs 2140 and 2150 are indicated by arrows 2103 and 2105 which show how far (substantially) the blue light travels within the eyepiece waveguide before out-coupling in regions 2142 of CPE 2140 and 2152 of CPE 2150.

[0165]

[0252] Figure 21C is a simplified top view of the world side of an eyepiece waveguide with multi-directional emission in which blue light is emitted in a second direction, according to an embodiment of the present invention. Figure 21D is a simplified top view of the user side of an eyepiece waveguide with multi-directional emission by the blue light emitted in the second direction shown in Figure 21C. Referring to Figures 21C and 21D, the blue light is emitted from the blue ICGs 2160 and 2161 in the 10 o'clock direction and hits the region 2142 of the CPE 2140 and the region 2152 of the CPE 2150. The total path lengths from the ICGs 2160 and 2161 to the respective centers of the CPEs 2140 and 2150 are indicated by the arrows 2107 and 2109, which show how far (substantially) the blue light travels within the eyepiece waveguide before out-coupling in the regions 2142 of the CPE 2140 and the region 2152 of the CPE 2150. Based on the comparison of the path lengths shown in Figures 21A / 21B and Figures 21C / 21D, the design shown in Figures 21C / 21D is superior to the design shown in Figures 21A / 21B with respect to the efficiency of the blue light. This result was verified by simulations based on full-rate ray tracing.

[0166]

[0253] The inventors have determined that the problem of blue light absorption becomes severe in materials (especially glasses) having a high value of refractive index, such as n > 2.0, including those listed in Table 2. Therefore, for the selection of such high refractive index materials, the multi-directional emission design provides a degree of freedom for optimizing the design with high blue efficiency in mind. However, such a selection usually sacrifices a reduction in the maximum field of view enabled by that multi-directional emission design.

[0167]

[0254] Figure 22A is a simplified k-space diagram showing the field of view, ICG lattice vectors, OPE lattice vectors, and CPE lattice vectors of an eyepiece waveguide with multi-directional emission, according to another embodiment of the present invention. Figure 22B is a simplified top view of the world side of an eyepiece waveguide with multi-directional emission, according to another embodiment of the present invention.

[0168]

[0255] The structure shown in Fig. 22B is different from the other structures described in this specification. The red light incident on the red ICG 2210 is radiated into the eyepiece waveguide in a region near the center of the ring, and then interacts with an orthogonal pupil expander (OPE-red) that redirects the red light to the k-space position normally occupied by the red light. Subsequently, the red light is out-coupled from the CPE together with the green and blue lights. This structure results in a red bounce density comparable to that of the green and blue bounce densities.

[0169]

[0256] Referring to Fig. 22A, the lattice vector k ICG-red represents diffraction by the red ICG 2210 in the first distance and direction in k-space, and the lattice vector k ICG-green-blue represents diffraction by the green / blue ICG 2212 in the second distance and direction in k-space. In this embodiment, the first distance is different from the second distance, and the first direction is also different from the second direction. Therefore, the red ICG 2210 and the green / blue ICG 2212 in-couple light (corresponding to the lattice vector k ICG-red and the lattice vector k ICG-green-blue ) and generate the respective red FOV 2220, green FOV 2222, and blue FOV 2224. The region 2242 of the CPE 2240 has a lattice corresponding to the lattice vector OPE-red and shifts the red FOV 2220 in k-space to the red FOV 2231. The diffraction in the region 2244 of the CPE 2240 shifts the green FOV 2222 and the blue FOV 2224 in k-space to the green FOV 2233 and shifts the blue FOV 2235 in k-space to the blue FOV 2235. Diffraction from a CPE (not shown) coupled to the opposite side of the eyepiece waveguide corresponding to the lattice vector CPE-k2 shown in Fig. 22B results in out-coupling from the eyepiece waveguide.

[0170]

[0257] Accordingly, the emitted red light interacts with the lattice corresponding to the lattice vector OPE-red in region 2242, diffracts towards the center of CPE2240, and is out-coupled there. Other implementations of this design are also included within the scope of the present invention. Similar to the other structures described herein, the embodiment shown in FIG. 22B provides an extension of the horizontal FOV beyond what is available using a design based on unidirectional emission.

[0171]

[0258] FIG. 23 shows the overlap of images in k-space with corresponding eyepiece designs according to various embodiments of the present invention. In FIG. 23, schematic views 2310, 2320, and 2330 show how the images overlap with a portion of the corresponding k-space for various embodiments. For ease of explanation, only a portion of the annular region between r = n = 1 and r = n = 2 is shown.

[0172]

[0259] ICG2312 is shown in relation to FOV2314 corresponding to schematic view 2310. The physical position of the projector of the AR wearable can affect the ICG position and form factor of the AR wearable. Accordingly, the placement of the ICG with respect to the user's eye is shown by a line extending across FOV2314 that is aligned with the ICG. Accordingly, various designs, including designs that place the projector / ICG adjacent to the temple or adjacent to the nose, are enabled by embodiments of the present invention. In particular, in combination with the multi-synthesizer (CPE, EPE, OPE) elements described herein, using the multi-directional emission (i.e., ICG function) performance described herein, in various projector directions for the user's AR virtual image, it is possible to out-couple in combination with an increased FOV of light.

[0173]

[0260] As shown in FIG. 23, the ICG can be arranged above the user's eye as shown by ICG2312, which corresponds to the case where the image is present in the lower central part of the annulus in k-space, or arranged above and to the side of the user's eye as shown by ICG2322, which corresponds to the case where the image is present in the lower left part of the annulus in k-space, or arranged above and to the side of the user's eye as shown by ICG2324, which corresponds to the case where the image is present in the lower left part of the annulus in k-space, or arranged to the side of the user's eye as shown by ICG2332, which corresponds to the case where the image is present in the left part of the annulus in k-space. Therefore, the shape of the wearable can vary in relation to the various shapes of the eyepiece waveguide described herein. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0174]

[0261] FIG. 24 shows a perspective view of a wearable device 2400 according to an embodiment of the present invention. The wearable device 2400 includes a frame 2402 configured to support one or more projectors 2404 at various positions along a surface facing the interior of the frame 2402 as shown. In some embodiments, the projector 2404 can be attached at a position near the temple 2406. Alternatively, or additionally, another projector can be disposed at position 2408. Such a projector may include, for example, one or more liquid crystal on silicon (LCoS) modules, a micro LED display, or a fiber scanning device, or operate in relation to them. In some embodiments, the light from the projector 2404 or the projector disposed at position 2408 can be guided into the eyepiece waveguide 2410 for display to the user's eye. The projector disposed at position 2412 can be made somewhat smaller due to the proximity it gives the projector to the waveguide system. The closer it is, the less light is lost when the waveguide system guides the light from the projector into the eyepiece waveguide 2410. In some embodiments, the projector at position 2412 can be utilized together with the projector 2404 or the projector disposed at position 2408. Although not shown, in some embodiments, the projector can also be positioned at a location under the eyepiece waveguide 2410. The wearable device 2400 including sensors 2414 and 2416 is also shown. The sensors 2414 and 2416 can take the form of forward and lateral optical sensors configured to characterize the real-world environment surrounding the wearable device 2400.

[0175]

[0262] Also, the examples and embodiments described herein are for illustrative purposes only, and in light of which various modifications or changes may be suggested to those skilled in the art, and it is understood that they should be included within the spirit and scope of the present application and the appended claims.

Claims

1. A projector, An eyepiece waveguide that supports multi-directional radiation, wherein the eyepiece waveguide has a world side and a user side, A first set of one or more incoupling diffractive optical elements coupled to the world side of the eyepiece waveguide, A first subset of the first set of one or more incoupling diffractive optical elements is operable to diffract a first light into the eyepiece waveguide, and the diffracted first light is characterized by a first angular range, A second subset of the first set of one or more incoupling diffractive optical elements is operable to diffract a second light into the eyepiece waveguide, and the diffracted second light is characterized by a second angular range different from the first angular range, a first set of one or more incoupling diffractive optical elements, A second set of one or more incoupling diffractive optical elements coupled to the user side of the eyepiece waveguide, A third subset of the second set of one or more incoupling diffractive optical elements is operable to diffract light within the first angular range, a second set of one or more incoupling diffractive optical elements An eyepiece waveguide comprising: A synthetic pupil expander An AR headset comprising:

2. The AR headset according to claim 1, wherein a fourth subset of the second set of one or more incoupling diffractive optical elements is operable to diffract light within the second angular range.

3. The AR headset according to claim 1, wherein the AR headset includes a single waveguide.

4. The AR headset according to claim 1, wherein the eyepiece waveguide supports the propagation of light of multiple wavelengths.

5. The AR headset according to claim 1, wherein the synthetic pupil expander is operable to laterally diffuse light within the eyepiece waveguide and outcouple the light through the user side of the eyepiece waveguide.

6. The AR headset according to claim 1, wherein at least one of the first set of one or more incoupling diffractive optical elements or the second set of one or more incoupling diffractive optical elements overlaps.

7. An eyepiece waveguide for augmented reality applications, wherein the eyepiece waveguide comprises a substrate, a set of in-coupling diffractive optical elements coupled to the substrate, a first subset of the set of in-coupling diffractive optical elements being operable to diffract light in the substrate along a first range of propagation angles, a second subset of the set of in-coupling diffractive optical elements being operable to diffract light in the substrate along a second range of propagation angles, and a synthetic pupil expander diffractive optical element coupled to the substrate The eyepiece waveguide. **Claim 8** The eyepiece waveguide according to claim 7, wherein the first subset of the set of in-coupling diffractive optical elements is characterized by a first grating period, and the second subset of the set of in-coupling diffractive optical elements is characterized by a second grating period that is greater than the first grating period. **Claim 9** The eyepiece waveguide according to claim 7, wherein the synthetic pupil expander diffractive optical element comprises a first region characterized by a first grating direction and a second region characterized by a second grating direction different from the first grating direction. **Claim 10** The eyepiece waveguide further comprises a second set of in-coupling diffractive optical elements coupled to the substrate, a first subset of the second set of in-coupling diffractive optical elements being operable to diffract light in the substrate along the first range of propagation angles, The eyepiece waveguide according to claim 7. **Claim 11** The set of in-coupling diffractive optical elements is coupled to the substrate on a world side surface, The second set of in-coupling diffractive optical elements is coupled to the substrate on a user side surface facing the world side surface, The eyepiece waveguide according to claim 10. **Claim 12** The eyepiece waveguide according to claim 7, further comprising a second synthetic pupil expander diffractive optical element coupled to the substrate. **Claim 13** The synthetic pupil expander diffractive optical element is coupled to the substrate on a world side surface, The second synthetic pupil expander diffractive optical element is coupled to the substrate on a user side surface facing the world side surface, The eyepiece waveguide according to claim 12. **Claim 14** The eye-piece waveguide is optically coupled to a projector operable to output a red wavelength, a green wavelength, and a blue wavelength, and the eye-piece waveguide is operable to support light propagation at the red wavelength, the green wavelength, and the blue wavelength. The eye-piece waveguide according to claim 7.

15. The eye-piece waveguide according to claim 7, wherein the substrate has a refractive index between 1.8 and 2.

3.

16. The eye-piece waveguide according to claim 7, wherein the substrate includes silicon carbide having a refractive index of 2.

7.

17. The eye-piece waveguide according to claim 7, wherein the substrate includes a polymer resin having a refractive index between 1.3 and 2.

6.

18. The eye-piece waveguide according to claim 7, wherein the substrate has a refractive index between 1.8 and 2.7, and the set of in-coupling diffractive optical elements has a structure etched into the substrate.

19. The eye-piece waveguide according to claim 7, wherein the substrate includes a support structure and a layer having a refractive index between 1.8 and 2.7 coupled to the support structure, and the set of in-coupling diffractive optical elements has a structure etched into the layer.

20. The eye-piece waveguide according to claim 7, wherein the set of in-coupling diffractive optical elements has a structure etched into the substrate.

21. The eye-piece waveguide according to claim 20, further comprising a layer having a refractive index between 1.8 and 2.7 coupled to the substrate.

22. An eye-piece waveguide for augmented reality applications, the eye-piece waveguide comprising: a substrate; a set of in-coupling diffractive optical elements coupled to the substrate, the set of in-coupling diffractive optical elements comprising: 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; a set of in-coupling diffractive optical elements; a synthetic pupil expander diffractive optical element coupled to the substrate, the synthetic pupil expander diffractive optical element comprising: a first portion facing the world side surface and including a first region characterized by a first lattice vector and a second region characterized by a second lattice vector; A second portion facing the user side and including a third region characterized by the first lattice vector and a fourth region characterized by the third lattice vector, and A synthetic pupil expander diffractive optical element including An eyepiece waveguide including

23. The eyepiece waveguide according to claim 22, wherein the first in-coupling diffractive optical element and the second in-coupling diffractive optical element are characterized by a first lattice period, and the third in-coupling diffractive optical element is characterized by a second lattice period smaller than the first lattice period.

24. The eyepiece waveguide according to claim 22, wherein the first region is characterized by a first lattice direction, and the second region is characterized by the first lattice direction.

25. The eyepiece waveguide according to claim 22, wherein the third region is characterized by a first lattice direction, and the second region is characterized by a second lattice direction different from the first lattice direction.

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

27. 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 the world side, 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 the user side facing the world side, The eyepiece waveguide according to claim 26.

28. The eyepiece waveguide according to claim 26, wherein the fourth in-coupling diffractive optical element and the fifth in-coupling diffractive optical element are characterized by a first lattice period, and the sixth in-coupling diffractive optical element is characterized by a second lattice period smaller than the first lattice period.

29. The eye-piece waveguide according to claim 22, optically coupled to a projector operable to output a red wavelength, a green wavelength, and a blue wavelength, the eye-piece waveguide being operable to support light propagation at the red wavelength, the green wavelength, and the blue wavelength.

30. The eye-piece waveguide according to claim 22, wherein the first region is disposed on the world side surface facing the third region disposed on the user side surface.

31. The eye-piece waveguide according to claim 22, wherein the second region is disposed on the world side surface facing the fourth region disposed on the user side surface.

32. The first in-coupling diffractive optical element and the second in-coupling diffractive optical element are characterized by a lattice vector k Ｌ thereby The third in-coupling diffractive optical element is characterized by a lattice vector k Ｈ and The first region and the third region are characterized by a lattice vector k １ and wherein the second region is characterized by a lattice vector k ３ and wherein the fourth region is characterized by a lattice vector k ２ and The eye-piece waveguide according to claim 22.

33. The diffraction paths of the red wavelength and the green wavelength are k Ｌ → k ２ → k ３ and the diffraction path of the blue wavelength is k Ｈ → k １ → k ２ The IOL waveguide according to claim 32, wherein:

Images