Method and system for pupil separation in a diffraction eyepiece waveguide display

Abstract

The pupil splitting system includes an input surface, a central portion including a set of dichroic mirrors, a first reflective surface disposed laterally relative to the central portion, and a second reflective surface disposed laterally relative to the central portion. The pupil splitting system also includes an exit surface including the central surface operable to transmit light within a first wavelength range, a first peripheral surface adjacent to the central surface operable to transmit light within a second wavelength range, and a second peripheral surface adjacent to the central surface and opposite the first peripheral surface. The second peripheral surface is operable to transmit light within a third wavelength range.

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 024,858, filed on May 14, 2020, entitled "Method and System for Pupil Separation in a Diffractive Eyepiece Waveguide Display", which is hereby incorporated by reference in its entirety for all purposes.

Background Art

[0002] Modern computing and display technologies have facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, where digitally reproduced images or portions thereof are presented to a viewer in a manner such that they appear or are perceived as if they were real. Virtual reality, i.e., "VR" scenarios, typically involve the presentation of digital or virtual image information without transparency to other actual real-world visual inputs. Augmented reality, i.e., "AR" scenarios, typically involve the presentation of digital or virtual image information as an augmentation to the visualization of the actual world around the viewer.

[0003] Despite the progress made in these display technologies, there remains a need in the art for improved methods and systems for augmented reality systems, particularly display systems.

Summary of the Invention

Means for Solving the Problems

[0004] The present invention generally relates to methods and systems for waveguide displays. More specifically, embodiments of the present invention provide methods and systems that provide a pupil separation system that can be integrated with a waveguide display, also referred to as an eyepiece waveguide. The present invention is applicable to various applications in computer vision and image display systems.

[0005] As described herein, embodiments of the present invention relate to a method and system for spatially separating light reflected from a scanning mirror into a plurality of primary colors (e.g., three primary colors: red, green, and blue) on a diffractive eyepiece forming part of an augmented reality display device, and directing the spatially separated light beams to corresponding internally coupled gratings, also referred to as internally coupled grating regions.

[0006] According to embodiments of the present invention, a pupil separation system is provided. The pupil separation system includes an input surface, a central portion including a set of dichroic mirrors, a first reflective surface positioned laterally to the central portion, a second reflective surface positioned laterally to the central portion, and an output surface. The output surface includes a central surface operable to transmit light within a first wavelength range, a first circumferential surface adjacent to the central surface and operable to transmit light within a second wavelength range, and a second circumferential surface adjacent to the central surface and opposite to the first circumferential surface. The second circumferential surface is operable to transmit light within a third wavelength range.

[0007] According to another embodiment, an optical system is provided. The optical system includes a scanning mirror operable to rotate about an axis and a pupil separation system. The pupil separation system includes an input surface and a central portion including a set of dichroic mirrors, a first reflective surface positioned laterally to the central portion, a second reflective surface positioned laterally to the central portion, and an output surface. The output surface includes a central surface operable to transmit light within a first wavelength range, a first circumferential surface adjacent to the central surface and operable to transmit light within a second wavelength range, and a second circumferential surface adjacent to the central surface and opposite to the first circumferential surface. The second circumferential surface is operable to transmit light within a third wavelength range. The optical system further includes an eyepiece waveguide comprising a first waveguide layer including a first internally coupled grating (ICG) corresponding to a first wavelength range, and a second waveguide layer including a second ICG corresponding to a second wavelength range, the second ICG including a second waveguide layer spatially offset from the first ICG, and a third waveguide layer including a third ICG corresponding to a third wavelength range. The third ICG is spatially offset from the first and second ICGs.

[0008] According to a particular embodiment of the present invention, a method for operating a projector is provided, which includes a scanning mirror and an eyepiece waveguide. The method includes the step of receiving image light in the scanning mirror, the image light characterized by a first wavelength range, a second wavelength range, and a third wavelength range. The method also includes the steps of rotating the scanning mirror about an axis, scanning the received image light along a first direction perpendicular to the axis, receiving the scanned image light at the input surface of a pupil separation system, and reflecting light in the first wavelength range from a first dichroic mirror of the pupil separation system. The method further includes the steps of reflecting light in the first wavelength range from a first circumferential surface of the pupil separation system, reflecting light in the second wavelength range from a second dichroic mirror of the pupil separation system, reflecting light in the second wavelength range from a second circumferential surface of the pupil separation system, and transmitting light in the third wavelength range.

[0009] In one embodiment, light within a first wavelength range is incident on the internal coupling grating of the first waveguide layer of the eyepiece waveguide. Light within a second wavelength range may be incident on the internal coupling grating of the second waveguide layer of the eyepiece waveguide, and light within a third wavelength range may be incident on the internal coupling grating of the third waveguide layer of the eyepiece waveguide. The method may also include the step of filtering light within the first wavelength range using a first color filter coupled to a pupil separation system, and / or filtering light within the second wavelength range using a second color filter coupled to a pupil separation system. Furthermore, the method may include the step of filtering light within a third wavelength range using a third color filter coupled to a pupil separation system. The first and second dichroic mirrors may be orthogonal to each other and intersect, for example, along a line parallel to the axis.

[0010] Numerous advantages are achieved by the methods of the present invention, which are superior to conventional techniques. For example, embodiments of the present invention provide a method and system that provides spatial separation between colors output by a scanned input light source, such that spatially separated light beams can be directed to different positions on an eyepiece waveguide. These and other embodiments of the invention, along with many of their advantages and features, will be described in further detail in conjunction with the following text and accompanying figures. The present invention provides, for example, the following: (Item 1) It is a pupil separation system, Input surface and The central part includes a set of dichroic mirrors, A first reflective surface positioned laterally to the central portion, A second reflective surface positioned laterally to the central portion, The output surface, A central surface that is operable to transmit light within a first wavelength range, A first circumferential surface adjacent to the central surface and capable of transmitting light within a second wavelength range, A second circumferential surface adjacent to the central surface and facing the first circumferential surface, wherein the second circumferential surface is operable to transmit light within a third wavelength range, and Including the output surface and A pupil separation system equipped with this system. (Item 2) The pupil separation system is the pupil separation system according to item 1, characterized by a refractive index greater than or equal to 2.0. (Item 3) The pupil separation system described in item 2, wherein the refractive index is approximately 2.5. (Item 4) The pupil separation system according to item 1, wherein the set of dichroic mirrors comprises a first dichroic mirror oriented at 45° to the input surface and a second dichroic mirror oriented at -45° to the input surface. (Item 5) The pupil separation system according to item 1, wherein the first wavelength range comprises a red wavelength range, the second wavelength range comprises a blue wavelength range, and the third wavelength range comprises a green wavelength range. (Item 6) A red color filter placed on the central surface, A blue color filter placed on the first circumferential surface, A green color filter and The pupil separation system described in item 5 is further equipped with the following: (Item 7) The first reflective surface is oriented at a 45° angle to the input surface. The second reflective surface is oriented at -45° to the input surface. The pupil separation system described in item 1. (Item 8) The pupil separation system according to item 1, further comprising a reflective coating disposed on the first reflective surface and the second reflective surface. (Item 9) The dichroic mirrors of the set of dichroic mirrors are mutually orthogonal and intersecting, in the pupil separation system described in item 1. (Item 10) The dichroic mirrors of the set of dichroic mirrors intersect along lines parallel to the input surface, in the pupil separation system according to item 1. (Item 11) An optical system, A scanning mirror that can move to rotate around an axis, It is a pupil separation system, Input surface and The central part includes a set of dichroic mirrors, A first reflective surface positioned laterally to the central portion, A second reflective surface positioned laterally to the central portion, The output surface, A central surface that is operable to transmit light within a first wavelength range, A first circumferential surface adjacent to the central surface and capable of transmitting light within a second wavelength range, A second circumferential surface adjacent to the central surface and facing the first circumferential surface, wherein the second circumferential surface is operable to transmit light within a third wavelength range, and Including the output surface and A pupil separation system equipped with, An eyepiece waveguide, A first waveguide layer including a first internally coupled grating (ICG) corresponding to the first wavelength range, A second waveguide layer including a second ICG corresponding to the second wavelength range, wherein the second ICG is spatially offset from the first ICG, A third waveguide layer including a third ICG corresponding to the third wavelength range, wherein the third ICG is spatially offset from the first ICG and the second ICG, and Includes an eyepiece waveguide and An optical system equipped with [the necessary components]. (Item 12) The pupil separation system according to item 11, wherein the first ICG, the second ICG, and the third ICG are reflective ICGs. (Item 13) The pupil separation system is the pupil separation system according to item 11, characterized by a refractive index greater than or equal to 2.0. (Item 14) The pupil separation system described in item 13, wherein the refractive index is approximately 2.5. (Item 15) The pupil separation system according to item 11, wherein the set of dichroic mirrors comprises a first dichroic mirror oriented at 45° to the input surface and a second dichroic mirror oriented at -45° to the input surface. (Item 16) The pupil separation system according to item 11, wherein the first wavelength range comprises a red wavelength range, the second wavelength range comprises a blue wavelength range, and the third wavelength range comprises a green wavelength range. (Item 17) A red color filter placed on the central surface, A blue color filter placed on the first circumferential surface, A green color filter and The pupil separation system described in item 16 is further equipped with the following: (Item 18) The first reflective surface is oriented at a 45° angle to the input surface. The second reflective surface is oriented at -45° to the input surface. The pupil separation system described in item 11. (Item 19) The pupil separation system according to item 11, further comprising a reflective coating disposed on the first reflective surface and the second reflective surface. (Item 20) The pupil separation system according to item 11, wherein the dichroic mirrors of the set of dichroic mirrors are mutually orthogonal and intersect along lines parallel to the axes. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a simplified cross-sectional schematic diagram illustrating a pupil separation system for an eyepiece waveguide according to an embodiment of the present invention.

[0012] [Figure 2] Figure 2 is a simplified plan view of the pupil separation system shown in Figure 1.

[0013] [Figure 3] Figure 3 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 1, which is fabricated using the first material.

[0014] [Figure 4] Figure 4 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 1, which is fabricated using a second material.

[0015] [Figure 5] Figure 5 is a simplified cross-sectional schematic diagram illustrating a pupil separation system for an eyepiece waveguide according to another embodiment of the present invention.

[0016] [Figure 6] Figure 6 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 5, which is fabricated using the first material.

[0017] [Figure 7] Figure 7 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 5, which is fabricated using a second material.

[0018] [Figure 8] Figure 8 is a simplified cross-sectional schematic diagram illustrating a pupil separation system for an eyepiece waveguide according to yet another embodiment of the present invention.

[0019] [Figure 9] Figure 9 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 8.

[0020] [Figure 10] Figure 10 is a simplified flowchart illustrating a method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to an embodiment of the present invention.

[0021] [Figure 11] Figure 11 is a simplified flowchart illustrating a method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to an embodiment of the present invention.

[0022] [Figure 12] Figure 12 is a simplified flowchart illustrating a method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to an embodiment of the present invention. [Modes for carrying out the invention]

[0023] Detailed explanation The present invention relates, in general terms, to methods and systems relating to projection display systems, including wearable displays. More specifically, embodiments of the present invention provide methods and systems that provide pupil separation systems that can be integrated with waveguide displays, also known as eyepiece waveguides. The present invention is applicable to various applications in computer vision and image display systems.

[0024] Micro-electromechanical (MEMS) scanning mirrors are components that can be used with a light source, including a laser diode or light-emitting diode (LED), within a compact and efficient projector, making them suitable for use in augmented reality applications. In some conventional designs, laser light in three primary colors (e.g., red, blue, and green) is collimated using a dichroic mirror so that the combined beam can be scanned using a MEMS scanning mirror. In some implementations using diffractive eyepiece waveguides, light from the MEMS scanning mirror is directed to an internally coupled grating (ICG) region on the corresponding layer of the diffractive eyepiece waveguide, where each layer corresponds to one of the primary colors. These implementations utilize a transmissive series grating design. However, the low efficiency of transmissive series grating designs can present challenges. Furthermore, potential problems associated with these implementations may include color crosstalk between layers of the diffractive eyepiece waveguide, lack of parallelism between layers of the diffractive eyepiece, which can lead to the production of afterimage images, and equivalents.

[0025] According to embodiments of the present invention, one or more of the primary colors used in the display design are spatially separated and guided to isolate the ICG region in order to mitigate design shortcomings associated with conventional techniques. Furthermore, embodiments of the present invention enable the use of metallized ICG that can be blazed to provide high lattice efficiency.

[0026] Figure 1 is a simplified cross-sectional schematic diagram illustrating a pupil separation system for an eyepiece waveguide according to an embodiment of the present invention. As shown in Figure 1, the eyepiece waveguide 105 is shown to include three waveguide layers, each associated with a primary color. Thus, in this embodiment, the three waveguide layers include a green waveguide layer 105g, a red waveguide layer 105r, and a blue waveguide layer 105b. In other embodiments, more than three waveguide layers are used to increase the number of colors available in the display, to increase the number of depth planes or equivalent. As will be obvious to those skilled in the art, the waveguide layers of an eyepiece waveguide receive input light in an internally coupled diffracting optical element that diffracts the input light received in the plane of the waveguide. In the embodiment illustrated in Figure 1, the internally coupled diffractive optical elements are each implemented as an internally coupled grating (ICG). However, this particular diffractive structure is not required by the present invention, and other diffractive structures containing various diffractive optical elements may be used and are within the scope of this disclosure. As shown in Figure 1, the green waveguide layer 105g contains a green ICG 150, the red waveguide layer 105r contains a red ICG 140, and the blue waveguide layer 105b contains a blue ICG 130. After propagation within the waveguide layers, the light is subsequently externally coupled toward the user's eye by, for example, an exit pupil expander (EPE) (not shown) or other suitable diffractive external coupling element. Using the three primary colors, a multicolor display can be assembled using the three waveguide layers shown in Figure 1. In the embodiment illustrated in Figure 1, the refractive index of the eyepiece waveguide is 1.75.

[0027] In the eyepiece waveguide illustrated in Figure 1, each ICG is spatially separated from the others. Using the coordinate axes illustrated in Figure 1, light propagates toward the eyepiece waveguide in the longitudinal direction aligned with the z-axis. The lateral plane, defined by the xy plane, extends within and out of the plane. The ICGs are spatially offset from each other in this lateral plane. As shown in Figure 1, the blue ICG 130 is positioned to cover a first range of positions in the xy plane, the red ICG 140 is positioned to cover a second range of positions in the xy plane, and the green ICG 150 is positioned to cover a third range of positions in the xy plane. These ranges, spatially separated for each waveguide layer and forming distinct pupils, do not overlap. This architecture, which utilizes spatially separated and distinct pupils, can be referred to as a sub-pupil design.

[0028] In some projector designs, a scanning mirror is used to scan light containing all three primary colors (e.g., RGB light), which are modulated for each image. Therefore, as the light strikes the scanning mirror, all three colors are present at predetermined intensities as needed for a particular pixel. As described herein, pupil separation is used to spectrally and spatially separate the primary colors to provide spatially separated inputs, also referred to as pupils, for different waveguide layers.

[0029] Figure 1 illustrates a scanning mirror that reflects light, characterized by a predetermined field of view (FOV), e.g., 50° × 50°, with a convergence profile in at least one dimension. Without limiting the embodiments of the present invention, exemplary dimensions for the scanning mirror 102 may be approximately 4.6 mm × 1.5 mm, as shown. This mirror creates an FOV in the y-direction. For the purpose of clarity, other projection optics are not shown, but it should be understood that suitable projection optics may be utilized through which light travels prior to reaching the scanning mirror 102 in order to form the pupil. As measured along the x-axis, the beam converges as shown, generally creating a pupil positioned in a predetermined longitudinal location inside the eyepiece waveguide 105. The internal coupling diffraction direction inside the waveguide is assumed to be along the x-direction, and it is beneficial to minimize the pupil size along this direction to minimize what is known as re-bounce loss within the waveguide. As an example, for a 500 μm thick waveguide with a refractive index of 1.75 and a field of view of 50° × 50°, the pupil may be approximately 1.3 mm. In certain embodiments, the pupil is positioned in a longitudinal position aligned with the red ICG140, but this is not required by the present invention. The beam diverges so as to be measured along the y-axis, thereby providing a pupil with a rectangular geometric shape as illustrated in Figure 2. In other embodiments, other scanning projector architectures, such as scanning fiber projectors and equivalents, may be utilized.

[0030] Referring to Figure 1, the scanning mirror 102 rotates and oscillates around the x-axis in a manner that scans the input light along the y-axis, i.e., in a direction perpendicular to the plane of the figure. In the x-direction, the FOV along the plane of the figure is created by a second scanning mirror (not shown) located upstream in the optical path, for example, via an Offner relay type array. Thus, using this set of scanning mirrors, the projector creates an FOV positioned in the xy-plane, extending both in the plane of the figure (i.e., in the x-direction) and perpendicular to the plane of the figure (i.e., in the y-direction).

[0031] Light from the scanning mirror 102 is illustrated as a pupil separation system 110 entering at the input surface 112. In some embodiments, the input surface 112, which may be referred to as the incident surface, is anti-reflective coated to maintain low reflectivity across the field of view and for all colors. The pupil separation system 110 includes a central portion 113a containing two crossing dichroic mirrors oriented at ±45° with respect to the direction of propagation of the incident principal ray. Referring to Figure 1, both sets of dichroic mirrors (i.e., a first dichroic mirror 114 and a second dichroic mirror 120) are oriented at 45° to the input surface 112, specifically the first dichroic mirror 114 oriented at +45° to the input surface 112 and the second dichroic mirror 120 oriented at -45° to the input surface 112.

[0032] As shown in Figure 1, the first dichroic mirror 114 transmits red and blue wavelengths while reflecting green wavelengths. The second dichroic mirror 120 transmits red and green wavelengths while reflecting blue wavelengths. As shown in Figure 1, the first dichroic mirror 114 and the second dichroic mirror 120 are mutually orthogonal and intersect along a line parallel to the y-axis and the input surface 112.

[0033] Therefore, the first dichroic mirror 114 and the second dichroic mirror 120 are highly reflective with respect to one of the three primary colors and highly transmitt with respect to the other two primary colors across the FOV. Since red wavelengths (e.g., approximately 570 nm to 700 nm) are transmitted by both the first dichroic mirror 114 and the second dichroic mirror 120, light within these wavelengths propagates toward the red color filter 126 and the red ICG 140. The red color filter 126 is positioned on a central plane 126', laterally surrounded by two adjacent circumferential planes, as fully described below, and is operable to transmit light within the red wavelength range. Thus, light within the red wavelength range converges at the location of the red ICG 140, which corresponds to the diffraction internal coupling element with respect to the red waveguide layer 105r.

[0034] In the pupil separation system illustrated in Figure 1, a material with a reasonably high refractive index (n>2.0) is used to produce angular separation between light at various wavelengths, which are significantly less affected than angular separation in air. As will be obvious to those skilled in the art, this is beneficial for maintaining small spatial separation between colors, which is advantageous for providing a compact eyepiece waveguide. An additional discussion regarding the refractive index of the pupil separation system is provided in relation to Figures 3 and 4. In the embodiment illustrated in Figure 1, the overall active dimensions of the pupil separation system 110 are approximately 2.5 mm × 6 mm × 5 mm, which enables use in various compact architectures.

[0035] Referring again to Figure 1, green wavelengths (e.g., approximately 500 nm to 570 nm) are reflected from the first dichroic mirror 114 and propagate toward surface 116, which is formed by the interface between the material of the pupil separation system 110 and the surrounding environment, typically air. Surface 116 is formed on one surface of the first peripheral portion 113b, adjacent to the side of the central portion 113a. Surface 116 can be referred to as the first reflective surface. Due to the refractive index difference at surface 116 between the material of the first peripheral portion 113b and the surrounding environment, light at green wavelengths is reflected via total internal reflection (TIR) ​​and propagates toward the green color filter 118 and green ICG 150, which are located within the green waveguide layer 105g. The green color filter 118 is located on the first peripheral surface 118' adjacent to the central surface 126' and is operable to transmit light within the green wavelength range.

[0036] Similarly, blue wavelengths (e.g., approximately 400 nm to 500 nm) are reflected from the second dichroic mirror 120 and propagate toward surface 122, which is formed by the interface between the material of the pupil separation system 110 and the surrounding environment, typically air. Surface 122 is formed on one surface of the second peripheral portion 113c, which is adjacent to the side of the central portion 113a. Surface 120 can be referred to as the second reflective surface. Due to the refractive index difference at surface 122 between the material of the second peripheral portion 113c and the surrounding environment, light at blue wavelengths is reflected via TIR and propagates toward the blue color filter 124 and blue ICG 130, which are located within the blue waveguide layer 105b. The blue color filter 124 is located on the second peripheral surface 124' adjacent to the central surface 126' and is operable to transmit light within the blue wavelength range. As shown in Figure 1, the first reflective surface (i.e., surface 116) can be oriented at 45° to the input surface 112, and the second reflective surface (i.e., surface 120) can be oriented at -45° to the input surface 112.

[0037] Accordingly, the output surface 115 includes a central surface 126' which is operable to transmit light within a first wavelength range (e.g., the red wavelength range), a first circumferential surface 118' which is laterally adjacent to the central surface 126' and operable to transmit light within a second wavelength range (e.g., the green wavelength range), and a second circumferential surface 124' which is laterally adjacent to the central surface 126' and faces the first circumferential surface 118', i.e., positioned on the side of the central surface 126' opposite to the first circumferential surface 118'. The second circumferential surface 124' is operable to transmit light within a third wavelength range (e.g., the blue wavelength range).

[0038] TIR is utilized on surfaces 116 and 122 in the embodiment illustrated in Figure 1, but this is not required by the present invention. Alternatively, surfaces 116 and 122 may be coated with a reflective material (e.g., aluminum, silver, or equivalent) to form a reflective coating to provide a highly reflective surface when TIR conditions are not met. The reflective coating can be placed on a first reflective surface (i.e., surface 116) and a second reflective surface (i.e., surface 120). The distance between the scanning mirror 102 and the pupil separation system 110 (e.g., D=1.1 mm), the thickness of the pupil separation system 110 along the z-axis (e.g., 2.5 mm), the propagation distance within the pupil separation system 110, the distance between the pupil separation system 110 and the eyepiece waveguide 105, the refractive index of the pupil separation system 110 including potential differences in refractive index within different parts of the pupil separation system 110, the lateral spacing between the ICGs, the thickness of the green waveguide layer 105g, the red waveguide layer 105r, and the blue waveguide layer 105b (e.g., W=0.5 mm), and the spacing between the green waveguide layer 105g, the red waveguide layer 105r, and the blue waveguide layer 105b (e.g., 50 μm), and their equivalents are parameters that can be optimized based on the specific application. In some embodiments, it is preferable to utilize the small distance between ICGs in the x-direction, measured along the waveguide (e.g., 2.5 mm), which results in a design with a small lateral size for the focused beam at the ICG location.

[0039] As shown in Figure 1, color filters (e.g., three color filters) can be deposited on or otherwise optically coupled to the surface of a pupil separation system 110 adjacent to the eyepiece waveguide 105, which may be referred to as the output surface 115, the exit surface, or the exit plane. For example, a green color filter 118 can be positioned on the surface of the pupil separation system 110 adjacent to the eyepiece waveguide 105 (i.e., the output surface 115) to transmit light with green wavelengths and block or attenuate light outside the green wavelength band (i.e., red and blue wavelengths). Similarly, a red color filter 126 can be positioned on the surface of the pupil separation system 110 adjacent to the eyepiece waveguide 105 (i.e., the output surface 115) to transmit light with red wavelengths and attenuate or block light outside the red wavelength band (i.e., green and blue wavelengths). Finally, the blue color filter 124 can be positioned on the surface of the pupil separation system 110 adjacent to the eyepiece waveguide 105 (i.e., the output surface 115) to transmit light with blue wavelengths and attenuate or block light outside the blue wavelength band (i.e., red and green wavelengths). Thus, in addition to spectral separation achieved using the first dichroic mirror 114 and the second dichroic mirror 120, the use of color filters, e.g., a green color filter 118, a red color filter 126, and a blue color filter 124, can be implemented to reduce crosstalk between ICGs, which may arise from spurious reflections in the dichroic mirrors, reflections from interfaces including the surface of the waveguide layer, reflections from the ICGs, and equivalents.

[0040] Reflective ICGs can be used with the pupil separation system illustrated in Figure 1, which are characterized by high efficiency and low optical loss. In some embodiments, metallized ICGs can be used because the light incident on the ICG is spectrally separated, and crosstalk between ICGs is therefore reduced.

[0041] In the embodiment illustrated in Figure 1, the eyepiece waveguide 105 includes three waveguide layers (i.e., green waveguide layer 105g, red waveguide layer 105r, and blue waveguide layer 105b), while other embodiments utilize an eyepiece waveguide that includes six waveguide layers and is operable to support two depth planes. In examples, two image sources can be utilized and directed to a scanning mirror in a time-multiplexing manner. During a first time interval, image light associated with the first depth plane can be directed to the scanning mirror 102 and three ICGs as shown in Figure 1. During a second time interval, image light associated with the second depth plane can be directed to the scanning mirror at an offset angle, resulting in light in each of three wavelength bands directed to a second set of ICGs (not shown) that are slightly spatially offset along the x-axis, for example, slightly above the illustrated ICGs. Thus, two depth plane implementations are included within the scope of the present invention.

[0042] Figure 2 is a simplified plan view of the pupil separation system illustrated in Figure 1. As shown in Figure 2, the occupied area of ​​the pupil separation system 110 and the scanning mirror 102 are shown in comparison to the lateral dimensions of the blue ICG 130, red ICG 140, and green ICG 150. In an example, the pupil separation system may have dimensions of approximately 9 mm × 5 mm × 2.5 mm, and the scanning mirror may have dimensions of approximately 4.6 mm × 1.5 mm, as shown. In a particular embodiment, the blue ICG 130 has dimensions of 1.3 mm measured in the x direction and 4.6 mm measured in the y direction, the red ICG 140 has dimensions of 1.3 mm measured in the x direction and 4.0 mm measured in the y direction, and the green ICG 150 has dimensions of 1.3 mm measured in the x direction and 4.5 mm measured in the y direction. Thus, in the longitudinal direction perpendicular to the plane of the figure, the dimensions of the ICGs are considered to be able to vary as needed for a particular application. Those skilled in the art will recognize many variations, modifications, and substitutions.

[0043] Figure 3 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 1, fabricated using the first material. In this simulation, the refractive index of the pupil separation system 110 is 2.0, and the light leakage / uncapture percentage in the ICG is approximately 2.7%. As shown in Figure 3, the uncaptured light for the red ICG 140 is significantly less than the uncaptured light for the blue ICG 130 and green ICG 150, as indicated by the rays propagating to the right through the eyepiece waveguide. For this simulation, an ideal AR coating is applied as needed, ideal dichroic mirrors and color filters are used, and material dispersion is not included. Unlike the lateral dimensions shown in Figure 2, for the purposes of this simulation, the ICG size in the lateral plane for each color is equal to 1.3 mm in the x direction and 4 mm in the y direction. In Figure 3, the green waveguide layer 105g, the red waveguide layer 105r, and the blue waveguide layer 105b are shown for ease of comparison with Figure 1, and the ICG is positioned on the surface of the waveguide layer furthest from the pupil separation system 110. For this implementation, the distance from the input surface 112 to the surface of the pupil separation system 110 adjacent to the eyepiece waveguide 105 is 2.5 mm, the thickness of the waveguide layer is 0.5 mm, and there is a 50 μm space between adjacent waveguide layers. Other dimensions may be used in other implementations.

[0044] Figure 4 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 1, fabricated using a second material. In this simulation, the refractive index of the pupil separation system 110 is 2.5, and the light leakage / uncapture percentage in the ICG is approximately 0.7%. As shown in Figure 4, the uncaptured light for all three ICGs, namely red ICG 140, blue ICG 130, and green ICG 150, is significantly equal to and reduced compared to Figure 3, as indicated by the reduced number of rays propagating to the right through the eyepiece waveguide. For this simulation, an ideal AR coating is applied as needed, ideal dichroic mirrors and color filters are used, and material dispersion is not included. Unlike the lateral dimensions shown in Figure 2, for the purposes of this simulation, the ICG size in the lateral plane for each color is equal to 1.3 mm in the x direction and 4 mm in the y direction. In Figure 4, the green waveguide layer 105g, the red waveguide layer 105r, and the blue waveguide layer 105b are shown for ease of comparison with Figure 1, and the ICG is positioned on the surface of the waveguide layer furthest from the pupil separation system 110. For this implementation, the distance from the input surface 112 to the surface of the pupil separation system 110 adjacent to the eyepiece waveguide 105 is 2.5 mm, the thickness of the waveguide layer is 0.5 mm, and there is a 50 μm space between adjacent waveguide layers. Other dimensions may be used in other implementations.

[0045] Comparing Figures 3 and 4, it is evident that the percentage of uncaptured light (i.e., leakage) by the ICG was measured and reduced from approximately 2.7% (Figure 3) to approximately 0.7% (Figure 4). The inventors have determined that both of these percentages are acceptable for a wide range of applications. In both simulations, the refractive index is above or equal to 2.0, which results in a large optical path length inside the pupil separation system, enabling the focusing of light to a small area in the ICG, and this increases optical efficiency. In other words, the use of a pupil separation system enables an extended working distance by using a high refractive index optical system that results in spatial separation of the pupil in the eyepiece waveguide. As will be obvious to those skilled in the art, increasing the refractive index increases the optical path length, which is the product of propagation distance and refractive index, enabling a more compact pupil separation system design with a reduced propagation distance. Although dispersion was not included in the simulations shown in Figures 3 and 4 for many optical materials, it should be noted that dispersion decreases with increasing wavelength, resulting in a higher refractive index at shorter wavelengths. As a result, light in the blue and green wavelength range will suffer a higher refractive index compared to light in the red wavelength range, enabling longer optical path lengths for blue and green wavelengths and further reducing the percentage of uncaptured light.

[0046] Referring again to Figure 1, the inventors have determined that the longitudinal position of the ICGs can be selected based on the influence of the refractive index values. As shown in Figure 1, the blue ICG 130 is positioned in an intermediate longitudinal position, with the green ICG 150 being closest to the pupil separation system 110 and the red ICG 140 being furthest from the pupil separation system 110. This arrangement takes advantage of the fact that blue wavelengths should have a higher refractive index compared to green wavelengths due to dispersion. The path length from the pupil separation system 110 to the red ICG 140 is shortest, and the light with red wavelengths is pathed as shown to form a pupil at the location of the red ICG 140. Since the light with blue wavelengths may have a higher refractive index, this light has a longer path length than green, and therefore the blue ICG 130 is positioned further from the pupil separation system 110 compared to the green ICG 150 to form a pupil for both blue and green wavelengths. In other embodiments, the green ICG 150 is positioned in an intermediate longitudinal position, with the blue ICG 130 closest to the pupil separation system 110 and the red ICG 140 furthest from the pupil separation system 110. Furthermore, in some embodiments, the red ICG 140 is closest to the pupil separation system 110, with the green ICG 150 and blue ICG 130 positioned either in an intermediate longitudinal position or in the furthest longitudinal position. Those skilled in the art will recognize numerous variations, modifications, and alternatives.

[0047] Figure 5 is a simplified cross-sectional schematic diagram illustrating a pupil separation system for an eyepiece waveguide according to another embodiment of the present invention. The pupil separation system illustrated in Figure 5 shares some common elements with the pupil separation system shown in Figure 1, and the discussions provided in relation to Figure 1 are applicable to Figure 5 as appropriate. In contrast to the pupil separation system illustrated in Figure 1, the ICGs shown in Figure 5 share overlaps among several ICGs and are offset relative to other ICGs. As shown in Figure 5, the blue ICG 530 is positioned to cover a first range of positions in the xy plane, and the red ICG 540 is positioned to cover a subset of the first range of positions in the xy plane. In other embodiments, the red ICG 540 may have a larger spatial range than the blue ICG 530 in the lateral plane (i.e., the xy plane). In addition, in some embodiments, the blue ICG 530 and the red ICG 540 share some overlaps but also include parts that are distinctly different from parts of other ICGs. The green ICG550 is positioned in the xy plane to cover a second range of positions that do not overlap with the first range of positions, thereby forming pupils for the spatially overlapping blue waveguide layer 505b and red waveguide layer 505r, and a pupil for the green waveguide layer 505g that is spatially separated and distinct from the blue waveguide layer 505b and red waveguide layer 505r. Thus, this sub-pupil design includes both spatially overlapping pupils and spatially separated, distinct pupils, as measured in the lateral (i.e., xy) plane.

[0048] In a manner similar to the pupil separation system discussed in relation to Figure 1, the scanning mirror 502 reflects light with a convergence profile, characterized by a predetermined field of view (FOV), for example, 50° × 50°. Without limiting the embodiments of the present invention, exemplary dimensions for the scanning mirror 502 are approximately 4.6 mm. 2It is possible that, for the purpose of clarity, other projection optics, though not shown, may be used, through which light travels prior to reaching the scanning mirror 502 in order to form the pupil. As measured along the x-axis, the beam converges as shown and generally forms a pupil located at a predetermined longitudinal position inside the eyepiece waveguide 505. In certain embodiments, the pupil is located at a longitudinal position aligned with the red ICG 540, although this is not required by the present invention. As measured along the y-axis, the beam diverges and thereby provides a pupil with a rectangular geometric shape, as illustrated in Figure 2. In other embodiments, other scanning projector architectures, e.g., scanning fiber projectors and equivalents, may be used.

[0049] Referring to Figure 5, the scanning mirror 502 rotates and oscillates around the x-axis in a manner that scans the input light along the y-axis, i.e., in a direction perpendicular to the plane of the figure. In the x-direction, the FOV along the plane of the figure is created by a second scanning mirror (not shown) located upstream in the optical path, for example, via an Offner relay type array. Thus, using this set of scanning mirrors, the projector creates an FOV positioned in the xy-plane, extending both in the plane of the figure (i.e., in the x-direction) and perpendicular to the plane of the figure (i.e., in the y-direction).

[0050] Light from the scanning mirror 502 is illustrated as a pupil separation system 510 entering at the input surface 511. In some embodiments, the input surface 511 is anti-reflective coated to maintain low reflectivity across the field of view and for all colors. The pupil separation system 510 includes a central portion containing a dichroic mirror oriented at ±45° with respect to the direction of propagation of the incident principal ray. As shown in Figure 5, the dichroic mirror 512 transmits red and blue wavelengths while reflecting green wavelengths. Thus, the dichroic mirror 512 is highly reflective with respect to green wavelengths and highly transparent with respect to blue and red wavelengths across the field of view. Because blue and red wavelengths are transmitted by the dichroic mirror 512, light within these wavelengths propagates toward the blue ICG 530 and red ICG 540. Therefore, light in the blue wavelength range converges at the location of the blue ICG 530, which corresponds to the diffraction internal coupling element for the blue waveguide layer 505b, and light in the red wavelength range converges at the location of the red ICG 540, which corresponds to the diffraction internal coupling element for the red waveguide layer 505r.

[0051] Referring again to Figure 5, the green wavelength is reflected from the dichroic mirror 512 and propagates toward the surface 514, which is formed by the interface between the material of the pupil separation system 510 and the surrounding environment, which is typically air. Due to the refractive index difference at surface 514, the light at the green wavelength is reflected via TIR and propagates toward the green ICG 550 located within the green waveguide layer 505g.

[0052] TIR is utilized on surface 514 in the embodiment illustrated in Figure 5, but this is not required by the present invention. Alternatively, surface 514 may be coated with a reflective material (e.g., aluminum, silver, or equivalent) to provide a highly reflective surface. The distance between the scanning mirror 502 and the pupil separation system 510 (e.g., D=1.1 mm), the thickness of the pupil separation system 510 along the z-axis, the propagation distance within the pupil separation system 510, the distance between the pupil separation system 510 and the eyepiece waveguide 505, the refractive index of the pupil separation system 510 including potential differences in refractive index in different parts of the pupil separation system 510, the lateral spacing between ICGs, the thickness of the green waveguide layer 505g, the red waveguide 505r, and the blue waveguide 505b (e.g., W=0.5 mm), and the spacing between the green waveguide layer 505g, the red waveguide 505r, and the blue waveguide 505b, and their equivalents are parameters that can be optimized based on the specific application. In some embodiments, it is preferable to utilize a small distance between ICGs (e.g., 2.5 mm) in the x-direction measured along the waveguide, which results in a design with a small lateral size for the focused beam at the location of the ICGs.

[0053] Although not shown in Figure 5, color filters similar to those discussed in relation to Figure 1 can be deposited on the surface of the pupil separation system 510 adjacent to the eyepiece waveguide 505, or otherwise optically coupled to it. For example, a green color filter can be positioned on the surface of the pupil separation system 510 adjacent to the eyepiece waveguide 505 and the green ICG 550 to transmit light with green wavelengths and attenuate or block light outside the green wavelength band (i.e., red and blue wavelengths). Similarly, a notch filter that transmits blue and red wavelengths can be positioned on the surface of the pupil separation system 510 adjacent to the eyepiece waveguide 505 and the blue ICG 530 and red ICG 540 to transmit light with blue and red wavelengths and attenuate or block light between the blue and red wavelength bands (i.e., green wavelengths). Therefore, in addition to spectral separation achieved using the dichroic mirror 512, the use of color filters can be implemented to reduce crosstalk between ICGs that may arise from spurious reflections in the dichroic mirror, reflections from interfaces including the surface of the waveguide layer, reflections from the ICG, and equivalents. In other embodiments, the waveguide layer may include a spectrally selective absorbing material to perform the function provided by the color filter; for example, the green waveguide layer 505g may include a material that absorbs light at blue and red wavelengths. Similarly, absorbing materials may also be used in conjunction with other waveguide layers.

[0054] In the implementation illustrated in Figure 5, the blue ICG 530 is a transmissive ICG that transmits red wavelengths while diffracting light in the blue wavelength range into the blue waveguide layer 505b, while the red ICG 540 and green ICG 550 are reflective ICGs. Due to the large wavelength difference between the blue and red wavelength ranges, the crosstalk between the blue ICG 530 and the red ICG 540 is low, or low enough to meet the system requirements. As will be obvious to those skilled in the art, low crosstalk can arise from several sources. For example, if light at red wavelengths is diffracted into the blue waveguide layer 505b, the angle at which these red wavelengths propagate within the blue waveguide layer 505b is large enough that they do not propagate (e.g., do not suffer TIR) or propagate with low efficiency. In addition, in the embodiment illustrated in Figure 5, a dichroic mirror 512 is used to spectrally separate light in the green wavelength band. However, the dichroic mirror 512 can be replaced by a polarization-selective mirror that selectively redirects light at green wavelengths, characterized by a first polarization state, compared to light at blue and red wavelengths, characterized by a second polarization state orthogonal to the first polarization state. Thus, in addition to the use of dichroic mirror-based beam splitters, polarization beam splitters can be utilized. In these polarization-based devices, one or more additional polarizations maintaining the element or polarization control element can be integrated to provide the desired polarization state in the ICG. Those skilled in the art will recognize many variations, modifications, and substitutions.

[0055] In the pupil separation system illustrated in Figure 5, a material with a reasonably high refractive index (n>2.0) is used to produce angular separation between light at various wavelengths, where these wavelengths are significantly less angularly separated than those that may occur in air. For example, the pupil separation system can be fabricated using glass with a refractive index of 2.0 and an overall active dimension of approximately 2.5 mm × 2.5 mm × 5 mm. Alternatively, a pupil separation system with an overall active dimension of approximately 2.8 mm × 2.8 mm × 5.6 mm can be used, utilizing glass with a refractive index of 2.5.

[0056] Figure 6 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 5, fabricated using the first material. In this simulation, the refractive index of the pupil separation system 510 is 2.0, and the light leakage / uncapture percentage in the ICG is approximately 2%. As shown in Figure 6, the uncaptured light for the blue ICG 530 and red ICG 540 is significantly less than the uncaptured light for the green ICG 550, as indicated by the rays propagating to the right through the eyepiece waveguide. For this simulation, an ideal AR coating is applied as needed, ideal dichroic mirrors and color filters are used, and material dispersion is not included. In Figure 6, the green waveguide layer 505g, blue waveguide 505b, and red waveguide 505r are shown to facilitate comparison with Figure 5, and the ICG is placed on the surface of the waveguide layer furthest from the pupil separation system 510. For this implementation, the dimensions of the pupil separation system 510 are approximately 2.5 mm × 4 mm × 4 mm, the distance from the input surface 515 of the pupil separation system 510 to the surface of the pupil separation system 510 adjacent to the eyepiece waveguide 505 is 2.5 mm, the thickness of the waveguide layer is 0.5 mm, and there is a 50 μm space between adjacent waveguide layers. Other dimensions may be used in other implementations.

[0057] Figure 7 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 5, fabricated using a second material. In this simulation, the refractive index of the pupil separation system 510 is 2.5, and the light leakage / uncapture percentage in the ICG is approximately 1%. For this simulation, an ideal AR coating is applied as needed, ideal dichroic mirrors and color filters are used, and material dispersion is not included. For the purposes of this simulation, dimensions as discussed in relation to Figure 6 are used. Other dimensions may be used in other implementations.

[0058] Figure 8 is a simplified cross-sectional schematic diagram illustrating a pupil separation system for an eyepiece waveguide according to yet another embodiment of the present invention. The pupil separation system illustrated in Figure 8 shares some common elements with the pupil separation systems shown in Figures 1 and 5, and the discussions provided in relation to Figures 1 and 5 are applicable to Figure 8 as necessary.

[0059] Referring to Figure 8, the three parts of the pupil separation system 810 are illustrated to be arranged along the x-axis. The first part 810a includes an input surface 812 and is implemented as a dichroic beam splitter that transmits light in the red wavelength range and reflects light in the blue and green wavelength ranges. As shown in Figure 8, the first part 810a includes a green dichroic mirror 814 and a blue dichroic mirror 816. In some embodiments, a single dichroic mirror (i.e., a high-pass filter) is used that transmits light in the red wavelength range while reflecting light in both the blue and green wavelength ranges. The second part 810b is displaced along the x-axis relative to the first part 810a and is implemented as a dichroic beam splitter that transmits light in the green wavelength range and reflects light in the blue wavelength range. Thus, the second part 810b includes a blue dichroic mirror 820. The third portion 810c is displaced along the x-axis relative to the second portion 810b and is implemented as a right-angle prism that reflects light in the green wavelength range. Thus, the third portion 810c includes a reflective surface 822 that operates using TIR or may be coated with a reflective coating such as a metallized coating.

[0060] Therefore, light in the red wavelength range passes through the first section 810a and collides on the red ICG 830 in the red waveguide layer 805r; light in the blue wavelength range is reflected from the blue dichroic mirror 816 in the first section 810a and the blue dichroic mirror 820 in the second section 810b and collides on the blue ICG 840 in the blue waveguide layer 805b; and light in the green wavelength range is reflected from the green dichroic mirror 814 in the first section 810a, passes through the blue dichroic mirror 820 in the second section 810b, is reflected from the reflective surface 822 in the third section 810c and collides on the green ICG 850 in the green waveguide layer 805g.

[0061] To reduce crosstalk between ICGs, which can arise from spurious reflections in the dichroic mirror, reflections from interfaces including the waveguide layer surface, reflections from the ICG, and equivalents, color filters can be used, as shown in Figure 8. In particular, a red color filter 818 is positioned on the surface of the first portion 810a of the pupil separation system 810 adjacent to the eyepiece waveguide 805 to transmit light with red wavelengths and attenuate or block light outside the red wavelength band (i.e., green and blue wavelengths). Furthermore, a green color filter 824 is positioned on the surface of the third portion 810c of the pupil separation system 810 adjacent to the eyepiece waveguide 805 to transmit light with green wavelengths and attenuate or block light outside the green wavelength band (i.e., red and blue wavelengths). Although not shown in Figure 8, a blue color filter can be used in conjunction with the second portion 810b. Those skilled in the art will recognize many variations, modifications, and substitutions.

[0062] Figure 9 shows the simulation results demonstrating the operation of the pupil separation system illustrated in Figure 8. In this simulation, the refractive index of the pupil separation system 810 is 2.5, and the light leakage / uncapture percentage in the ICG is approximately 2%. As shown in Figure 9, the uncaptured light for the blue ICG 840 is significantly less than the uncaptured light for the red ICG 830, which is less than the uncaptured light for the green ICG 850, as indicated by the rays propagating to the right through the eyepiece waveguide. For this simulation, an ideal AR coating is applied as needed, ideal dichroic mirrors and color filters are used, and no material dispersion is included. In Figure 9, the green waveguide layer 805g, blue waveguide 805b, and red waveguide 805r are shown to facilitate comparison with Figure 8, and the ICG is located on the surface of the waveguide layer furthest from the pupil separation system 810.

[0063] Figure 10 is a simplified flowchart illustrating a method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to an embodiment of the present invention. Method 1000 includes the step of receiving image light in the scanning mirror (1002). The image light is characterized by a first wavelength range, a second wavelength range, and a third wavelength range, for example, primary colors red, green, and blue. The method also includes the steps of rotating the scanning mirror about an axis (1004), scanning the received image light along a first direction perpendicular to the axis (1006), and receiving the scanned image light at the input surface of a pupil separation system (1008).

[0064] The method further includes the steps of reflecting light within a first wavelength range from a first dichroic mirror of the pupil separation system (1010) and reflecting light within a first wavelength range from a first circumferential surface of the pupil separation system (1012). The first and second dichroic mirrors may be orthogonal to each other and intersect in a line perpendicular to the axis. In some embodiments, the first and second dichroic mirrors intersect in a line parallel to the input surface. The method also includes the steps of reflecting light within a second wavelength range from a second dichroic mirror of the pupil separation system (1014) and reflecting light within a second wavelength range from a second circumferential surface of the pupil separation system (1016). The method further includes the step of transmitting light within a third wavelength range (1018).

[0065] In some embodiments, the waveguide projector includes an eyepiece waveguide comprising a plurality of waveguide layers, wherein light within a first wavelength range is incident on an internal coupling grating of the first waveguide layer, light within a second wavelength range is incident on an internal coupling grating of the second waveguide layer, and light within a third wavelength range is incident on an internal coupling grating of the third waveguide layer. In some embodiments, light within the first wavelength range is filtered using a first color filter coupled to a pupil separation system, light within the second wavelength range is filtered using a second color filter coupled to a pupil separation system, and light within the third wavelength range is filtered using a third color filter coupled to a pupil separation system.

[0066] It should be understood that the specific steps illustrated in Figure 10 provide a particular method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to embodiments of the present invention. Other sequences of steps may also be carried out according to alternative embodiments. For example, alternative embodiments of the present invention may carry out the steps outlined above in a different order. Furthermore, the individual steps illustrated in Figure 10 may include a number of substeps that can be carried out in various sequences as required for the individual steps. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0067] Figure 11 is a simplified flowchart illustrating a method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to an embodiment of the present invention. Method 1100 includes the step of receiving image light in the scanning mirror (1102). The image light is characterized by a first wavelength range, a second wavelength range, and a third wavelength range, for example, primary colors red, green, and blue. The method also includes the steps of rotating the scanning mirror about an axis (1104), scanning the received image light along a first direction perpendicular to the axis (1106), and receiving the scanned image light at the input surface of a pupil separation system (1108).

[0068] The method further includes the steps of reflecting light within a first wavelength range from a dichroic mirror of the pupil separation system (1110) and reflecting light within the first wavelength range from the circumferential surface of the pupil separation system (1112). The dichroic mirror can be oriented at a 45° angle to the input surface, and the axis perpendicular to the input surface and the dichroic mirror can be parallel. The method further includes the step of transmitting light within a second wavelength range and a third wavelength range (1114).

[0069] In some embodiments, the waveguide projector includes an eyepiece waveguide comprising a plurality of waveguide layers, wherein light within a first wavelength range is incident on an internal coupling grating of the first waveguide layer, light within a second wavelength range is incident on an internal coupling grating of the second waveguide layer, and light within a third wavelength range is incident on an internal coupling grating of the third waveguide layer. In some embodiments, light within the first wavelength range is filtered using a first color filter coupled to a pupil separation system, light within the second wavelength range is filtered using a second color filter coupled to a pupil separation system, and light within the third wavelength range is filtered using a third color filter coupled to a pupil separation system.

[0070] It should be understood that the specific steps illustrated in Figure 11 provide a particular method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to embodiments of the present invention. Other sequences of steps may also be carried out according to alternative embodiments. For example, alternative embodiments of the present invention may carry out the steps outlined above in a different order. Furthermore, the individual steps illustrated in Figure 11 may include multiple substeps, which may be carried out in various sequences as required for the individual steps. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0071] Figure 12 is a simplified flowchart illustrating a method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to an embodiment of the present invention. Method 1200 includes the step of receiving image light in the scanning mirror (1202). The image light is characterized by a first wavelength range, a second wavelength range, and a third wavelength range, for example, primary colors red, green, and blue. The method also includes the steps of rotating the scanning mirror about an axis (1204), scanning the received image light along a first direction perpendicular to the axis (1206), and receiving the scanned image light at the input surface of a pupil separation system (1208).

[0072] The method further includes the steps of reflecting light within a first wavelength range from a first dichroic mirror of the pupil separation system (1210) and reflecting light within the first wavelength range from the circumferential surface of the pupil separation system (1212). The method also includes the steps of reflecting light within a second wavelength range from a second dichroic mirror of the pupil separation system (1214) and reflecting light within a second wavelength range from a second dichroic mirror of the pupil separation system (1216). The method further includes the step of transmitting light within a third wavelength range (1218). The first dichroic mirror and the second dichroic mirror can be parallel to each other.

[0073] In some embodiments, the waveguide projector includes an eyepiece waveguide comprising a plurality of waveguide layers, wherein light within a first wavelength range is incident on an internal coupling grating of the first waveguide layer, light within a second wavelength range is incident on an internal coupling grating of the second waveguide layer, and light within a third wavelength range is incident on an internal coupling grating of the third waveguide layer. In some embodiments, light within the first wavelength range is filtered using a first color filter coupled to a pupil separation system, light within the second wavelength range is filtered using a second color filter coupled to a pupil separation system, and light within the third wavelength range is filtered using a third color filter coupled to a pupil separation system.

[0074] It should be understood that the specific steps illustrated in Figure 12 provide a particular method for operating a projector, including a scanning mirror and an eyepiece waveguide, according to embodiments of the present invention. Other sequences of steps may also be carried out according to alternative embodiments. For example, alternative embodiments of the present invention may carry out the steps outlined above in a different order. Furthermore, the individual steps illustrated in Figure 12 may include a number of substeps that can be carried out in various sequences as required for the individual steps. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0075] Furthermore, it should be understood that the examples and embodiments described herein are for illustrative purposes only, and various modifications or changes in light thereof are proposed to those skilled in the art and should be included within the spirit, authority and scope of the appended claims.

Claims

1. It is a pupil separation system, Input surface and A central portion including a set of dichroic mirrors, wherein the set of dichroic mirrors includes a first dichroic mirror and a second dichroic mirror intersecting each other in the central portion, A first reflective surface positioned laterally with respect to the central portion, A second reflective surface positioned laterally to the central portion, The output surface, A central surface that transmits light within a first wavelength range, A first circumferential surface adjacent to the central surface, which transmits light within a second wavelength range, wherein the light within the second wavelength range is reflected by the first dichroic mirror of the set of dichroic mirrors before being reflected by the first reflective surface, A second circumferential surface adjacent to the central surface and facing the first circumferential surface, wherein the second circumferential surface transmits light within a third wavelength range, and the light within the third wavelength range is reflected by the second dichroic mirror of the set of dichroic mirrors before being reflected by the second reflective surface. Including the output surface and Equipped with, The central surface, the first circumferential surface, and the second circumferential surface are arranged to output light in the same direction. Pupil separation system.

2. The pupil separation system according to claim 1, wherein the pupil separation system as a whole is characterized by a refractive index greater than or equal to 2.

0.

3. The pupil separation system according to claim 2, wherein the refractive index is approximately 2.

5.

4. The pupil separation system according to claim 1, wherein the set of dichroic mirrors comprises a first dichroic mirror oriented at 45° to the input surface and a second dichroic mirror oriented at -45° to the input surface.

5. The pupil separation system according to claim 1, wherein the first wavelength range comprises a red wavelength range, the second wavelength range comprises a blue wavelength range, and the third wavelength range comprises a green wavelength range.

6. A red color filter placed on the central surface, A blue color filter placed on the first circumferential surface, A green color filter and The pupil separation system according to claim 5, further comprising:

7. The first reflective surface is oriented at a 45° angle to the input surface. The pupil separation system according to claim 1, wherein the second reflective surface is oriented at -45° to the input surface.

8. The pupil separation system according to claim 1, further comprising a reflective coating disposed on the first reflective surface and the second reflective surface.

9. The pupil separation system according to claim 1, wherein the first dichroic mirror and the second dichroic mirror are mutually orthogonal and intersect.

10. The pupil separation system according to claim 1, wherein the first dichroic mirror and the second dichroic mirror intersect with each other.

11. An optical system, A scanning mirror that rotates around the axis, It is a pupil separation system, Input surface and The central part includes a set of dichroic mirrors, A first reflective surface positioned laterally with respect to the central portion, A second reflective surface positioned laterally to the central portion, The output surface, A central surface that transmits light within a first wavelength range, A first circumferential surface adjacent to the central surface, which transmits light within a second wavelength range, A second circumferential surface adjacent to the central surface and facing the first circumferential surface, wherein the second circumferential surface transmits light within a third wavelength range. The central surface, the first circumferential surface, and the second circumferential surface are arranged to output light in the same direction, and A pupil separation system equipped with, An eyepiece waveguide, A first waveguide layer including a first internally coupled grating (ICG) corresponding to the first wavelength range, A second waveguide layer including a second ICG corresponding to the second wavelength range, wherein the second ICG is spatially offset from the first ICG, A third waveguide layer comprising a third ICG corresponding to the third wavelength range, wherein the third ICG is spatially offset from the first ICG and the second ICG, and Includes an eyepiece waveguide and An optical system equipped with [the necessary components].

12. The optical system according to claim 11, wherein the first ICG, the second ICG, and the third ICG are reflective ICGs.

13. The optical system according to claim 11, wherein the pupil separation system is characterized by a refractive index greater than or equal to 2.0 for the pupil separation system as a whole.

14. The optical system according to claim 13, wherein the refractive index is approximately 2.

5.

15. The optical system according to claim 11, wherein the set of dichroic mirrors comprises a first dichroic mirror oriented at 45° to the input surface and a second dichroic mirror oriented at -45° to the input surface.

16. The optical system according to claim 11, wherein the first wavelength range comprises a red wavelength range, the second wavelength range comprises a blue wavelength range, and the third wavelength range comprises a green wavelength range.

17. A red color filter placed on the central surface, A blue color filter placed on the first circumferential surface, A green color filter and The optical system according to claim 16, further comprising:

18. The first reflective surface is oriented at a 45° angle to the input surface. The optical system according to claim 11, wherein the second reflective surface is oriented at -45° to the input surface.

19. The optical system according to claim 11, further comprising a reflective coating disposed on the first reflective surface and the second reflective surface.

20. The optical system according to claim 11, wherein the dichroic mirrors of the set of dichroic mirrors intersect with each other.

21. It is a pupil separation system, Input surface and The central part includes a set of dichroic mirrors, A first reflective surface positioned laterally with respect to the central portion, A second reflective surface positioned laterally to the central portion, The output surface, A central surface that transmits light within a first wavelength range, A first circumferential surface adjacent to the central surface, which transmits light within a second wavelength range, wherein the light within the second wavelength range is reflected by the set of dichroic mirrors before being reflected by the first reflective surface, A second circumferential surface adjacent to the central surface and facing the first circumferential surface, wherein the second circumferential surface transmits light within a third wavelength range, and the light within the third wavelength range is reflected by the set of dichroic mirrors before being reflected by the second reflective surface. Including the output surface and Equipped with, The first wavelength range comprises the red wavelength range, the second wavelength range comprises the blue wavelength range, and the third wavelength range comprises the green wavelength range. The system further comprises a red color filter disposed on the central surface, a blue color filter disposed on the first circumferential surface, and a green color filter disposed on the second circumferential surface. Pupil separation system.

22. The pupil separation system according to claim 21, wherein the pupil separation system as a whole is characterized by a refractive index greater than or equal to 2.

0.

23. The pupil separation system according to claim 22, wherein the refractive index is approximately 2.

5.

24. The pupil separation system according to claim 21, wherein the set of dichroic mirrors comprises a first dichroic mirror oriented at 45° to the input surface and a second dichroic mirror oriented at -45° to the input surface.

25. The first reflective surface is oriented at a 45° angle to the input surface. The pupil separation system according to claim 21, wherein the second reflective surface is oriented at -45° to the input surface.

26. The pupil separation system according to claim 21, further comprising a reflective coating disposed on the first reflective surface and the second reflective surface.

27. The pupil separation system according to claim 21, wherein the dichroic mirrors of the set of dichroic mirrors are mutually orthogonal and intersect.

28. The pupil separation system according to claim 21, wherein the dichroic mirrors of the set of dichroic mirrors intersect with each other.

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