Projector architecture incorporating artifact reduction

Abstract

To provide a favorable projector architecture incorporating artifact mitigation.SOLUTION: An eyepiece lens unit with optical filters includes a set of waveguide layers including a first waveguide layer and a second waveguide layer. The first waveguide layer is disposed in a first lateral plane and includes a first incoupling diffractive element disposed at a first lateral position, a first waveguide, and a first outcoupling diffractive element. The second waveguide layer is disposed in a second lateral plane adjacent to the first lateral plane and includes a second incoupling diffractive element disposed at a second lateral position, a second waveguide, and a second outcoupling diffractive element. The eyepiece lens unit also includes a set of optical filters including a first optical filter positioned at the first lateral position and operable to attenuate light outside a first spectral band and a second optical filter positioned at the second lateral position and operable to attenuate light outside a second spectral band.SELECTED DRAWING: Figure 10B

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 459,559, filed February 15, 2017, entitled "METHOD AND SYSTEM FOR MULTI-PUPIL DISPLAY SYSTEM WITH LIQUID CRYSTAL SHUTTER," U.S. Provisional Patent Application No. 62 / 459,964, filed February 16, 2017, entitled "METHOD AND SYSTEM FOR REDUCTION OF OPTICAL ARTIFACTS IN AUGMENTED REALITY DEVICES," and U.S. Provisional Patent Application No. 62 / 592,607, filed November 30, 2017, entitled "PROJECTOR ARCHITECTURE INCORPORATING ARTIFACT MITIGATION," the disclosures of which are incorporated herein by reference in their entireties for all purposes. [Background technology]

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

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

[0004] The present disclosure generally relates to methods and systems related to projection display systems, including wearable displays. More specifically, embodiments of the present disclosure provide methods and systems for eyepiece units with one or more integrated polarizers and improved system performance. In other embodiments, a white light source is used in conjunction with an LCOS-based projector and a shutter that operates synchronously with the LCOS-based projector. The present disclosure is applicable to a variety of applications in computer vision and image display systems.

[0005] In some projection display systems, light from a projector can be coupled into an eyepiece, which in turn projects an image into the viewer's eye. In addition to light from the projector intended for the viewer's eye, light originating from sources other than the projector, such as light from a ceiling light near the viewer and / or light from unintended reflections from components within the projector, can also be coupled into / into the eyepiece, thereby resulting in artifacts being presented to the viewer.

[0006] Therefore, to reduce the impact of such artifacts, embodiments of the present disclosure utilize optical elements, such as circular polarizers, placed in the optical path of a projection display to reduce the intensity of the artifacts. In some embodiments, split-pupil designs incorporating color filters are utilized to enable spectral filtering at sub-pupil locations of a distributed pupil system, mitigating the artifacts.

[0007] In some embodiments, the eyepiece is provided to include one or more optical filters for color separation between different waveguides of the eyepiece. The eyepiece may also utilize spatial positioning of the optical filters to reduce wavelength cross-coupling. Furthermore, in some embodiments, the projection display utilizes a white light source, a liquid crystal on silicon (LCOS)-based projector, and a shutter operating synchronously with the LCOS-based projector to reduce or eliminate artifacts. The present disclosure is applicable to various applications in computer vision and image display systems.

[0008] Numerous advantages over conventional techniques are achieved by the methods of the present disclosure. For example, embodiments of the present disclosure provide methods and systems that reduce or eliminate artifacts, including image persistence, in projection display systems. In addition, embodiments of the present disclosure reduce eye strain, reduce artifacts caused by stray light, and improve the resolution, dynamic range, color accuracy, ANSI contrast, and general signal-to-noise ratio of displayed images or videos.

[0009] In some embodiments, methods and systems are provided that reduce wavelength cross-coupling, resulting in improved brightness and contrast. Additionally, some embodiments of the present disclosure provide methods and systems that can reduce stray light and achieve improved contrast. Additionally, in some embodiments, improved color saturation of the image can be achieved by using more saturated color filters.

[0010] In some embodiments, LCOS-based wearable display systems are provided that are characterized by high fill factor and brightness images, thereby improving the user experience. Additionally, some embodiments provide larger pupil sizes, which can provide better image resolution and quality. Furthermore, embodiments of the present disclosure can also provide the flexibility to use white LEDs or RGB LEDs as elements of the projection system and provide ghosting reduction. These and other embodiments of the present disclosure, along with many of their advantages and features, are described in more detail in conjunction with the following text and accompanying figures. The present invention provides, for example, the following. (Item 1) An eyepiece unit including an optical filter, the eyepiece unit comprising: a set of waveguide layers including a first waveguide layer and a second waveguide layer, the first waveguide layer is disposed in a first lateral plane and includes a first in-coupling diffractive element disposed at a first lateral position, a first waveguide optically coupled to the first in-coupling diffractive element, and a first out-coupling diffractive element optically coupled to the first waveguide; the second waveguide layer is disposed in a second lateral plane adjacent to the first lateral plane and includes a second inward coupling diffractive element disposed at a second lateral position, a second waveguide optically coupled to the second inward coupling diffractive element, and a second outward coupling diffractive element optically coupled to the second waveguide; a set of waveguide layers; A set of optical filters including a first optical filter and a second optical filter, the first optical filter is positioned at the first lateral position and is operable to attenuate light outside a first spectral band; the second optical filter is positioned at the second lateral position and is operable to attenuate light outside a second spectral band. A set of optical filters An eyepiece unit comprising: (Item 2) the set of waveguide layers includes a third waveguide layer, and the set of optical filters includes a third optical filter; the third waveguide layer is disposed in a third lateral plane and includes a third inward coupling diffractive element disposed at a third lateral position, a third waveguide optically coupled to the third inward coupling diffractive element, and a third outward coupling diffractive element optically coupled to the third waveguide; the third optical filter is positioned at the third lateral position and is operable to attenuate light outside a third spectral band. Item 1. An eyepiece unit according to item 1. (Item 3) 3. The eyepiece lens unit of claim 2, wherein the first spectral band includes red wavelengths, the second spectral band includes green wavelengths, and the third spectral band includes blue wavelengths. (Item 4) Item 1, an eyepiece unit, wherein the first optical filter transmits at least one of green wavelengths or blue wavelengths. (Item 5) Item 1, an eyepiece unit, wherein the second optical filter transmits at least one of red wavelengths or blue wavelengths. (Item 6) Item 1. The eyepiece unit according to item 1, wherein the set of optical filters is disposed on a surface of a cover plate disposed in a third lateral plane adjacent to the first lateral plane. (Item 7) Item 7. An eyepiece unit as described in item 6, wherein the cover plate comprises a low transmittance medium between the sets of optical filters. (Item 8) The eyepiece lens unit described in item 1, wherein the first optical filter is positioned between a cover plate and the first waveguide layer, and the cover plate is positioned in a third lateral plane adjacent to the first lateral plane. (Item 9) Item 1, an eyepiece lens unit, wherein the second optical filter is disposed between the first waveguide layer and the second waveguide layer. (Item 10) Item 1, an eyepiece unit, wherein the first lateral position and the second lateral position are the same lateral position. (Item 11) The eyepiece unit described in item 1, wherein the eyepiece unit is positioned adjacent to a projection lens and the set of optical filters is positioned between the projection lens and the set of waveguide layers. (Item 12) Item 1, an eyepiece unit, wherein the first lateral position is displaced laterally relative to the second lateral position. (Item 13) Item 1, an eyepiece lens unit, wherein the first internal coupling diffractive element is configured to internally couple light within the first spectral band. (Item 14) Item 1, an eyepiece lens unit, wherein the second internal coupling diffractive element is configured to internally couple light within the second spectral band. (Item 15) 1. An artifact reduction system, comprising: a projector assembly; a set of imaging optics optically coupled to the projector assembly; an eyepiece optically coupled to the set of imaging optics, the eyepiece including an internal coupling interface; A set of optical filters, the set of optical filters comprising: a first optical filter operable to attenuate light outside the first spectral band; a second optical filter operable to attenuate light outside the second spectral band; a third optical filter operable to attenuate light outside the third spectral band; and a set of optical filters, including An artifact reduction system comprising: (Item 16) Item 16. The artifact reduction system of item 15, wherein the first spectral band includes red wavelengths, the second spectral band includes green wavelengths, and the third spectral band includes blue wavelengths. (Item 17) Item 16. The artifact reduction system of item 15, wherein the internal coupling interface includes a plurality of internal coupling diffractive elements arrayed around an optical axis. (Item 18) The projector assembly further comprises: a polarizing beam splitter (PBS); a set of spatially displaced light sources positioned adjacent to the PBS; a display panel disposed adjacent to the PBS; Equipped with Item 16. The artifact reduction system of item 15, wherein the set of imaging optics is positioned adjacent to the PBS. (Item 19) The projector assembly further comprises: a polarizing beam splitter (PBS); a set of spatially displaced light sources positioned adjacent a first side of the PBS; a collimator positioned adjacent to a second side of the PBS; a display panel disposed adjacent to a third side of the PBS; and Equipped with Item 16. The artifact reduction system of item 15, wherein the set of imaging optics is positioned adjacent to a fourth side of the PBS, the fourth side being positioned between the first side and the second side and opposite the third side. (Item 20) 20. The artifact reduction system of claim 19, wherein the display panel comprises at least one of a reflective display or an LCOS display. (Item 21) Item 16. The artifact reduction system of item 15, wherein the set of imaging optics is configured to form an image at the internal coupling interface. (Item 22) Item 16. The artifact reduction system of item 15, wherein the internal bonding interface further comprises at least one of a polarizing film, a wire grid polarizer, or a dielectric laminate coating. (Item 23) An eyepiece for projecting an image onto a viewer's eye, the eyepiece comprising: a first planar waveguide positioned in a first lateral plane, the first planar waveguide comprising a first diffractive optical element (DOE) disposed at a first lateral position; a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane, the second planar waveguide comprising a second DOE disposed at a second lateral position different from the first lateral position; a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane, the third planar waveguide comprising a third DOE disposed at a third lateral position different from the first lateral position and the second lateral position; an optical filter positioned between the second planar waveguide and the third planar waveguide, the optical filter being disposed at the third lateral position; and An eyepiece comprising: (Item 24) Item 24. The eyepiece of item 23, wherein the optical filter comprises a long-pass filter operable to transmit a first wavelength range and reflect a second wavelength range less than the first wavelength range. (Item 25) Item 25. The eyepiece according to item 24, wherein the first wavelength range includes 600 nm to 700 nm, and the second wavelength range includes 400 nm to 500 nm. (Item 26) Item 25. An eyepiece lens according to item 24, wherein the transmittance in the first wavelength range is about 90% or more. (Item 27) Item 25. An eyepiece lens according to item 24, wherein the reflectance in the second wavelength range is about 10% or less. (Item 28) Item 24. The eyepiece of item 23, wherein the optical filter comprises a long-pass filter operable to transmit a first wavelength range and absorb a second wavelength range. (Item 29) the first planar waveguide has a first surface and a second surface opposite the first surface, the first planar waveguide having a first region including the first lateral position and a second region, the first region configured to receive image light incident on its first surface, the image light including image light within a first wavelength range; the first DOE is disposed within the first region and configured to diffract image light within the first wavelength range into the first planar waveguide to be directed toward a second region of the first planar waveguide, and a portion of the image light is transmitted through the first planar waveguide. Item 24. The eyepiece according to item 23. (Item 30) the second planar waveguide has a first surface and a second surface opposite the first surface, the second planar waveguide having a first region including the second lateral position and a second region, the first region configured to receive image light within a second wavelength range; the second DOE is disposed within the first region and configured to diffract image light within the second wavelength range into the second planar waveguide so as to be directed toward a second region of the second planar waveguide. Item 24. The eyepiece according to item 23. (Item 31) the third planar waveguide has a first surface and a second surface opposite the first surface, the third planar waveguide having a first region including the third lateral location and a second region, the first region configured to receive image light within a third wavelength range; the third DOE is disposed within the first region and configured to diffract image light within the third wavelength range into the third planar waveguide so as to be directed toward a second region of the third planar waveguide. Item 24. The eyepiece according to item 23. (Item 32) Item 32. An eyepiece lens as described in Item 31, wherein the optical filter is disposed on a first surface of the third planar waveguide. (Item 33) Item 32. An eyepiece lens as described in Item 31, wherein the third DOE is disposed on a second surface of the third planar waveguide. (Item 34) Item 24. An eyepiece lens as described in Item 23, wherein the optical filter is disposed on a first surface or a second surface of the first planar waveguide, or on a first surface or a second surface of the second planar waveguide. (Item 35) An eyepiece for projecting an image onto a viewer's eye, the eyepiece comprising: a substrate positioned in a substrate lateral plane; a set of color filters disposed on the substrate, the set of color filters comprising: a first color filter disposed at a first lateral position and operable to pass a first range of wavelengths; a second color filter disposed at a second lateral position and operable to pass a second range of wavelengths; a third color filter disposed at a third lateral position and operable to pass a third wavelength range; a set of color filters comprising: a first planar waveguide positioned in a first lateral plane adjacent to the substrate lateral plane, the first planar waveguide comprising a first diffractive optical element (DOE) disposed at the first lateral position; a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane, the second planar waveguide comprising a second DOE disposed at the second lateral position; a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane, the third planar waveguide comprising a third DOE disposed at the third lateral position; An eyepiece comprising: (Item 36) Item 36. The eyepiece lens of item 35, wherein the first color filter comprises a first photoresist operable to transmit the first wavelength range and attenuate the second wavelength range and the third wavelength range. (Item 37) Item 36. The eyepiece lens of item 35, wherein the second color filter comprises a second photoresist operable to transmit the second wavelength range and attenuate the first wavelength range and the third wavelength range. (Item 38) Item 36. The eyepiece lens of item 35, wherein the third color filter comprises a third photoresist operable to transmit the third wavelength range and attenuate the first wavelength range and the second wavelength range. (Item 39) Item 36. The eyepiece lens of item 35, wherein at least one of the first color filter, the second color filter, or the third color filter comprises ultraviolet ink. (Item 40) Item 36. An eyepiece lens as described in item 35, wherein in a plan view, the first color filter is positioned opposite the third color filter around the optical axis. (Item 41) the substrate has a first side and a second side; the set of color filters is disposed on a first side of the substrate; a second side of the substrate facing the first planar waveguide; Item 36. The eyepiece according to item 35. (Item 42) the substrate has a first side and a second side; the set of color filters is disposed on a second side of the substrate; a second side of the substrate facing the first planar waveguide; Item 36. The eyepiece according to item 35. (Item 43) a fourth color filter disposed on the substrate at a fourth lateral position and operable to pass the second wavelength range; a fifth color filter disposed at a fifth lateral position and operable to pass the third wavelength range; Item 36. The eyepiece of item 35, further comprising: (Item 44) Item 44. An eyepiece lens as described in item 43, wherein in a plan view, the second color filter is positioned opposite the fourth color filter around the optical axis. (Item 45) a fourth planar waveguide positioned in a fourth lateral plane adjacent to the third lateral plane, the fourth planar waveguide comprising a fourth diffractive optical element (DOE) disposed at the fourth lateral position; a fifth planar waveguide positioned in a fifth lateral plane adjacent to the fourth lateral plane, the fifth planar waveguide comprising a fifth DOE disposed at the fifth lateral position; a sixth planar waveguide positioned in a sixth lateral plane adjacent to the fifth lateral plane, the sixth planar waveguide comprising a sixth DOE disposed at the sixth lateral position; Item 44. The eyepiece of item 43, further comprising: (Item 46) Item 44. The eyepiece lens of item 43, further comprising a sixth color filter positioned at a sixth lateral position and operable to pass the first wavelength range. (Item 47) Item 47. An eyepiece lens as described in item 46, wherein in a plan view, the fifth color filter is positioned opposite the sixth color filter around the optical axis. (Item 48) Item 36. The eyepiece according to item 35, wherein the first wavelength range includes 400 nm to 500 nm (blue), the second wavelength range includes 600 nm to 700 nm (red), and the third wavelength range includes 500 nm to 600 nm (green). (Item 49) An eyepiece for projecting an image onto a viewer's eye, the eyepiece comprising: a first planar waveguide positioned in a first lateral plane, the first planar waveguide comprising a first diffractive optical element (DOE) disposed at a first lateral position; a first optical filter coupled to the first planar waveguide at a second lateral position different from the first lateral position; a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane, the second planar waveguide comprising a second DOE disposed at the first lateral position; a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane, the third planar waveguide comprising a third DOE disposed at the first lateral position; a second optical filter positioned between the second planar waveguide and the third planar waveguide, the second optical filter being disposed at the first lateral position; and An eyepiece comprising: (Item 50) Item 49. An eyepiece lens as described in Item 49, wherein the first DOE is configured to diffract light having a first wavelength range, and the first optical filter comprises an absorption filter operable to absorb wavelengths outside the first wavelength range. (Item 51) Item 49. The eyepiece lens of item 49, wherein the first optical filter comprises a filter configured to transmit light within a first wavelength range and absorb at least a portion of light outside the first wavelength range. (Item 52) Item 52. The eyepiece lens of item 51, wherein the first optical filter is further configured to absorb at least a portion of light within a third wavelength range. (Item 53) Item 49, an eyepiece lens, wherein the second optical filter comprises a dichroic reflector. (Item 54) the second DOE is configured to diffract light with a second wavelength range; the second optical filter is configured to reflect light with the second wavelength range towards the second DOE for diffraction into the second planar waveguide. Item 49. The eyepiece according to item 49. (Item 55) Item 49, an eyepiece lens, wherein the first DOE is positioned within a first region located at the first lateral position, and the first optical filter is positioned within a second region of the first planar waveguide. (Item 56) Item 56. An eyepiece lens as described in Item 55, wherein the first optical filter is disposed within a cavity inside the first planar waveguide. (Item 57) Item 56. An eyepiece lens as described in Item 55, wherein the first optical filter is disposed on a first surface of the first planar waveguide. (Item 58) Item 49. An eyepiece lens as described in Item 49, wherein the first DOE is configured to diffract light within a first wavelength range including 400 nm to 500 nm (green), the second DOE is configured to diffract light within a second wavelength range including 400 nm to 500 nm (blue), and the third DOE is configured to diffract light within a third wavelength range including 600 nm to 700 nm (red). (Item 59) An eyepiece for projecting an image onto a viewer's eye, the eyepiece comprising: a substrate positioned in a substrate lateral plane, said substrate comprising: a first color filter disposed at a first lateral position and operable to pass a first range of wavelengths; a second color filter disposed at a second lateral position and operable to pass a second range of wavelengths; a substrate comprising: a first planar waveguide positioned in a first lateral plane adjacent to the substrate lateral plane, the first planar waveguide comprising: a first diffractive optical element (DOE) disposed at the first lateral position; a third color filter disposed at a third lateral position and operable to pass a third wavelength range; a first planar waveguide comprising: a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane, the second planar waveguide comprising a second DOE disposed at the third lateral position; a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane, the third planar waveguide comprising a third DOE disposed at the second lateral position; An eyepiece comprising: (Item 60) Item 59: An eyepiece lens according to item 59, wherein the substrate includes a first recess in which the first color filter is disposed and a second recess in which the second color filter is disposed. (Item 61) Item 59, an eyepiece lens, wherein the first planar waveguide includes a recess in which the third color filter is disposed. (Item 62) Item 59, an eyepiece lens, wherein the first color filter is operable to transmit the first wavelength range and attenuate the second wavelength range and the third wavelength range. (Item 63) Item 59, an eyepiece lens, wherein the second color filter is operable to transmit the second wavelength range and attenuate the first wavelength range and the third wavelength range. (Item 64) Item 59, an eyepiece lens, wherein the third color filter is operable to transmit the third wavelength range and attenuate the first wavelength range and the second wavelength range. (Item 65) Item 59, an eyepiece lens, wherein at least one of the first color filter, the second color filter, or the third color filter comprises an absorptive color filter. (Item 66) Item 59, an eyepiece lens, wherein in a plan view, the second color filter is positioned opposite the third color filter around the optical axis. (Item 67) The substrate further comprises: a fourth color filter disposed at a fourth lateral position and operable to pass the first wavelength range; a fifth color filter disposed at a fifth lateral position and operable to pass the second wavelength range; Item 59. An eyepiece according to item 59, comprising: (Item 68) Item 68. An eyepiece lens as described in item 67, wherein in a plan view, the fourth color filter is positioned opposite the fifth color filter. (Item 69) a fourth planar waveguide positioned in a fourth lateral plane adjacent to the third lateral plane, the fourth planar waveguide comprising a fourth diffractive optical element (DOE) disposed at the fourth lateral position; a fifth planar waveguide positioned in a fifth lateral plane adjacent to the fourth lateral plane, the fifth planar waveguide comprising a fifth DOE disposed at the fifth lateral position; a sixth planar waveguide positioned in a sixth lateral plane adjacent to the fifth lateral plane, the sixth planar waveguide comprising a sixth DOE disposed at the sixth lateral position; Item 68. The eyepiece of item 67, further comprising: (Item 70) Item 68. The eyepiece lens of item 67, further comprising a sixth color filter positioned at a sixth lateral position and operable to pass the third wavelength range. (Item 71) Item 71. An eyepiece lens as described in item 70, wherein in a plan view, the sixth color filter is positioned opposite the first color filter around the optical axis. (Item 72) Item 69. The eyepiece according to item 69, wherein the first wavelength range includes 600 nm to 700 nm, the second wavelength range includes 500 nm to 600 nm, and the third wavelength range includes 400 nm to 500 nm. (Item 73) An eyepiece for projecting an image onto a viewer's eye, the eyepiece comprising: a first planar waveguide positioned in a first lateral plane, the first planar waveguide comprising a first diffractive optical element (DOE) disposed at a first lateral position and defining a first boundary enclosing a first surface area; a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane, the second planar waveguide comprising a second DOE disposed at a second lateral location outside the first boundary, the second planar waveguide defining a second boundary enclosing a second surface area; a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane, the third planar waveguide comprising a third DOE disposed at a third lateral position outside the first boundary and outside the second boundary; An eyepiece comprising: (Item 74) Item 74. An eyepiece lens as described in Item 73, wherein the first DOE is positioned in a peripheral region of the first boundary. (Item 75) Item 74. An eyepiece lens as described in Item 73, wherein the first boundary comprises one or more peripheral cutouts. (Item 76) Item 74. An eyepiece lens as described in Item 73, wherein the first boundary comprises one or more central orifices. (Item 77) 1. A method for coupling light into an eyepiece comprising a plurality of planar waveguides, the method comprising: directing a first beam comprising a first wavelength to impinge on the eyepiece; coupling at least a portion of the first beam into a first planar waveguide of the plurality of planar waveguides; directing a second beam comprising a second wavelength to impinge on the eyepiece; coupling at least a portion of the second beam into a second planar waveguide of the plurality of planar waveguides; directing a third beam comprising a third wavelength to impinge on the eyepiece; and passing the transmitted portion of the third beam through an optical filter; coupling at least a portion of the transmitted portion of the third beam into a third planar waveguide of the plurality of planar waveguides; and A method comprising: (Item 78) 1. A method for coupling light into an eyepiece comprising a plurality of planar waveguides having a diffractive optical element associated with each of the plurality of planar waveguides, the method comprising: directing a first beam comprising a first wavelength, a second beam comprising a second wavelength, and a third beam comprising a third wavelength to impinge on the eyepiece at a first lateral position; coupling at least a portion of the first beam, at least a portion of the second beam, and at least a portion of the third beam into a first planar waveguide of the plurality of planar waveguides; attenuating at least a portion of the second beam and at least a portion of the third beam; coupling at least a second portion of the second beam into a second planar waveguide of the plurality of planar waveguides; passing the transmitted portion of the third beam through an optical filter; coupling at least a portion of the transmitted portion of the third beam into a third planar waveguide of the plurality of planar waveguides; and A method comprising: (Item 79) Item 79. The method of item 78, wherein the diffractive optical elements associated with each of the plurality of planar waveguides are aligned at the first lateral position. (Item 80) Item 79. The method of item 78, further comprising reflecting a reflected portion of the third beam from the optical filter. (Item 81) Item 81. The method of item 80, further comprising coupling at least a portion of the reflected portion of the third beam into the second planar waveguide. (Item 82) 1. An image display system, comprising: a single white light source for providing illuminating white light; an LCOS (liquid crystal on silicon) image projection device configured to receive the illuminating white light and sequentially project grayscale images at an optical pupil, each grayscale image configured to select pixels for each of three colors; a shutter having three shutter regions configured to divide the optical pupil into three sub-pupils for the three colors; a filter having three filter regions matched to the three shutter regions, each filter region having a color filter for one of the colors, the shutters and the filters being synchronized with the LCOS image projection device to sequentially project images in each of the three colors at a corresponding sub-pupil; an eyepiece having three waveguide layers, each waveguide layer including a diffractive optical element (DOE), the DOE aligned with a corresponding sub-pupil and configured to receive image light in one of the colors, the eyepiece configured to project a color image to a viewer; An image display system comprising: (Item 83) Item 83. The image display system of item 82, wherein the single white light source comprises a white light emitting diode (LED) light source. (Item 84) Item 83. The image display system of item 82, wherein the single white light source is configured to project a square or rectangular illumination light beam. (Item 85) Item 83. The image display system of item 82, wherein the shutter comprises a liquid crystal (LC) shutter. (Item 86) Item 83. An image display system according to item 82, wherein the three shutter regions are rectangular regions adjacent to each other. (Item 87) Item 83. An image display system according to item 82, wherein the three filter regions are rectangular regions adjacent to each other. (Item 88) Item 83. The image display system of item 82, wherein the three sub-pupils are rectangular regions adjacent to each other. (Item 89) Item 83. The image display system of item 82, wherein the DOE in each waveguide layer is configured to receive image light in one of the colors, diffract the image light into the waveguide layer, and propagate the image light in the waveguide layer in a propagation direction by total internal reflection (TIR). (Item 90) Item 90. The image display system of item 89, wherein the DOE in each waveguide layer is aligned with a corresponding sub-pupil for receiving the image light in one of the colors. (Item 91) Item 90. The image display system of item 89, wherein the DOEs in the waveguide layer are spatially displaced from each other. (Item 92) Item 90. The image display system of item 89, wherein the DOE in each waveguide layer has a rectangular shape and is elongated in a direction perpendicular to the propagation direction. (Item 93) 1. An image display system, comprising: a light source for providing color sequential illumination, the light source comprising a plurality of color LED light sources; an LCOS (liquid crystal on silicon) image projection device configured to receive the illumination from the plurality of color LED light sources and sequentially project color image light at an optical pupil for each of three colors, the optical pupil characterized by a pupil area and including a plurality of non-overlapping sub-pupils, each of the non-overlapping pupils of the plurality of non-overlapping sub-pupils characterized by a sub-pupil area; and Equipped with each of the plurality of LED light sources is configured to illuminate one of the plurality of non-overlapping sub-pupils; the sum of the sub-pupil areas is substantially equal to the pupil area; Image display system. (Item 94) Item 94. The image display system of item 93, wherein the sum of the sub-pupil areas is equal to the pupil area. (Item 95) the optical pupil has a circular shape; each of the plurality of LED light sources is configured to illuminate a sub-pupil that is a sector of the optical pupil; Item 94. The image display system according to item 93. (Item 96) the optical pupil has a square or rectangular shape; each of the plurality of LED light sources is configured to illuminate a sub-pupil that is a rectangular portion of the optical pupil; Item 94. The image display system according to item 93. (Item 97) the optical pupil has a square or rectangular shape; the plurality of LED light sources include a red LED, a blue LED, and a green LED; each LED of the plurality of LED light sources is configured to illuminate a sub-pupil that is a rectangular portion of the optical pupil; Item 94. The image display system according to item 93. (Item 98) the optical pupil has a circular shape; the plurality of LED light sources include two red LEDs, two blue LEDs, and two green LEDs; each LED of the plurality of LED light sources is configured to illuminate a sub-pupil that is a sector of the optical pupil; Item 94. The image display system according to item 93. (Item 99) the optical pupil has a square or rectangular shape; the plurality of LED light sources include two red LEDs, two blue LEDs, and two green LEDs; each LED of the plurality of LED light sources is configured to illuminate a sub-pupil that is a rectangular portion of the optical pupil; Item 94. The image display system according to item 93. (Item 100) the three colors are the three primary colors, the plurality of LED light sources comprises one or more LED light sources in each of the three primary colors; Item 94. The image display system according to item 93. (Item 101) Item 94. The image display system of item 93, wherein each of the plurality of LED light sources comprises an LED chip and a concentrator. (Item 102) Item 102. The image display system of item 101, wherein each concentrator is a compound parabolic concentrator (CPC). (Item 103) 1. An image display system, comprising: a light source for providing color sequential illumination, the light source comprising a plurality of LED light sources; an LCOS (liquid crystal on silicon) image projection device configured to receive the illumination from the plurality of color LED light sources and sequentially project color image light at an optical pupil for each of three colors, the optical pupil including a plurality of non-overlapping sub-pupils corresponding to the plurality of LED light sources; and an eyepiece having a plurality of waveguide layers, each waveguide layer including a diffractive optical element (DOE) aligned with a corresponding sub-pupil to receive the image light from a corresponding LED light source; Equipped with the LCOS image projection device generates high diffraction orders from each of the plurality of LED light sources; the DOE in each waveguide is positioned at a location displaced from the image from the higher diffraction orders; Image display system. (Item 104) 1. An image display system, comprising: a white light source for providing illuminating white light; an LCOS (liquid crystal on silicon) image projection device configured to receive the illuminating white light and sequentially project grayscale images at an optical pupil for each of the three colors; a shutter having a plurality of shutter regions configured to divide the optical pupil into a corresponding plurality of sub-pupils, one for each of the colors; a filter having a plurality of filter regions, each filter region having a color filter for one of the colors, each of the plurality of filter regions being matched to a corresponding one of the plurality of shutter regions; Equipped with The shutter is synchronized with the LCOS image projection device to sequentially project an image in each of the three colors onto one of the plurality of sub-pupils. (Item 105) Item 105. The image display system of item 104, wherein the white light source comprises a single white light source. (Item 106) Item 105. The image display system of item 104, wherein the shutter has six shutter regions, the filter has six filter regions, and the shutter and filter are matched to form six sub-pupils. (Item 107) Item 107. The image display system of item 106, further comprising an eyepiece having six waveguide layers, each waveguide layer including a diffractive optical element (DOE) aligned with a corresponding sub-pupil for receiving image light in one of the colors, the eyepiece configured to project color images at two depth planes. (Item 108) 1. An image display system, comprising: a plurality of white LED light sources for providing illumination white light; an LCOS (liquid crystal on silicon) image projection device configured to receive the illuminating white light and sequentially project grayscale images at an optical pupil for each of the three colors; a shutter device having a plurality of shutter regions configured to divide the optical pupil into a corresponding plurality of sub-pupils, one for each of the colors; a filter having a plurality of filter regions, each filter region having a color filter for one of the colors, each of the plurality of filter regions being matched to a corresponding one of the plurality of shutter regions; Equipped with The shutter is synchronized with the LCOS image projection device to sequentially project an image in each of the three colors onto one of the plurality of sub-pupils. (Item 109) the plurality of white LED light sources include a first white LED light source and a second white LED light source; the shutter device has three shutter regions; the filter has six color filter regions, namely, two red color filter regions, two green color filter regions, and two blue color filter regions; the first red color filter region, the first green color filter region, and the first blue color filter region are configured to receive light from the first white LED light source; the second red color filter region, the second green color filter region, and the second blue color filter region are configured to receive light from the second white LED light source. Item 109. The system of item 108. (Item 110) Item 109. The system of item 109, wherein the optical pupil comprises three sub-pixels. (Item 111) Item 109. The system of item 109, wherein the optical pupil comprises six sub-pixels. (Item 112) the first and second red color filter regions are aligned with two different shutter regions; the first and second green color filter regions are aligned with two different shutter regions; the first and second blue color filter regions are aligned with two different shutter regions; Item 109. The system of item 109. (Item 113) the plurality of white LED light sources include a first white LED light source and a second white LED light source; the shutter device includes a first shutter and a second shutter, each shutter including three shutter regions; the filter has six color filter regions, namely, two red color filter regions, two green color filter regions, and two blue color filter regions; a first red color filter region, a first green color filter region, and a first blue color filter region configured to receive light from the first white LED light source; the second red color filter region, the second green color filter region, and the second blue color filter region are configured to receive light from the second white LED light source. Item 109. The system of item 108. (Item 114) Item 114. The system of item 113, wherein the optical pupil comprises three sub-pixels. (Item 115) Item 114. The system of item 113, wherein the optical pupil comprises six sub-pixels. (Item 116) the first and second red color filter regions are aligned with two different shutter regions; the first and second green color filter regions are aligned with two different shutter regions; the first and second blue color filter regions are aligned with two different shutter regions; Item 114. The system of item 113. (Item 117) 1. An image display system, comprising: a single white light source for providing illuminating white light; an LCOS (liquid crystal on silicon) image projection device configured to receive the illuminating white light and project a full color image at an optical pupil; a shutter having three shutter regions configured to divide the optical pupil into three sub-pupils, each of the three sub-pupils associated with one of three colors; a filter having three filter regions, each filter region having a color filter for one of the three colors, the three filter regions being respectively aligned with the three shutter regions; Equipped with The image display system is configured to sequentially project images in each of the three colors at a respective sub-pupil. (Item 118) Item 117. The image display system of item 117, further comprising an eyepiece having three waveguide layers, each waveguide layer including a diffractive optical element (DOE) aligned with a corresponding sub-pupil for receiving image light in one of the colors, the eyepiece configured to project a color image to a viewer. (Item 119) Item 118. The image display system of item 117, wherein the single white light source is configured to project a square or rectangular illumination light beam. (Item 120) Item 118. An image display system according to Item 117, wherein the three shutter regions are rectangular regions adjacent to each other. (Item 121) Item 118. The image display system of item 117, wherein the LCOS image projection device comprises three LCOS panels, processes images in the three colors, and provides a combined full-color image. (Item 122) 1. An image display system, comprising: a white light source for providing illuminating white light; an LCOS (liquid crystal on silicon) based image projection device configured to receive the illuminating white light and project an image at an optical pupil; a shutter having a plurality of shutter regions configured to divide the optical pupil into a plurality of sub-pupils, one for each of a plurality of colors; a filter having a plurality of filter regions, each filter region having a color filter for one of the plurality of colors, each of the plurality of filter regions being aligned with a corresponding one of the plurality of shutter regions; Equipped with The shutter is synchronized with the LCOS image projection device to sequentially project an image in each of the plurality of colors onto one of the plurality of sub-pupils. (Item 123) Item 123. The image display system of item 122, wherein the plurality of sub-pupils are configured to fill the optical pupil. (Item 124) Item 123. The image display system of item 122, further comprising an eyepiece having a plurality of waveguide layers, each waveguide layer including a diffractive optical element (DOE) aligned with a corresponding sub-pupil for receiving image light in one of the plurality of colors, the eyepiece configured to project a color image to a viewer. (Item 125) Item 123. The image display system of item 122, wherein the plurality of colors are three primary colors, and the LCOS image projection device is configured to receive the illuminating white light and sequentially project grayscale images at the optical pupil for each of the three primary colors. (Item 126) Item 128. The image display system of item 127, wherein the LCOS image projection device comprises three LCOS panels, each of which is associated with one of three primary colors. (Item 127) Item 123. The image display system of item 122, wherein the LCOS image projection device is configured to receive the illuminating white light and project a full-color image at an optical pupil. (Item 128) 1. A method for displaying an image, the method comprising: Providing a white light source and an image projector; receiving white light from the white light source at the image projector; sequentially projecting grayscale images at the optical pupil, each grayscale image configured to select pixels for a corresponding one of three colors; providing a shutter and color filters for dividing the optical pupil into three sub-pupils for the three colors; synchronizing the shutter and color filter with the grayscale image to sequentially project an image in each of the three colors at a corresponding sub-pupil; providing an eyepiece having three waveguide layers; sequentially receiving images in each of the three colors at a corresponding waveguide layer to project the images to a viewer; A method comprising: (Item 129) Item 129. The method of item 128, wherein the white light source comprises a single white LED light source. (Item 130) Item 129. The method of item 128, further comprising receiving the white light and sequentially projecting a grayscale image at the optical pupil using an LCOS (liquid crystal on silicon) image projection device. (Item 131) Item 129. The method of item 128, wherein the shutter comprises a liquid crystal (LC) shutter having three shutter regions for dividing the optical pupil into three sub-pupils. (Item 132) Item 129. The method of item 128, wherein the color filter comprises three filter regions, each filter region including a color filter for one of the three colors. (Item 133) 1. A method for displaying an image, the method comprising: Providing a white light source and an image projector; receiving white light from the white light source at the image projector; projecting an image at an optical pupil; providing a shutter and a color filter for dividing the optical pupil into a plurality of sub-pupils; synchronizing the shutter and color filter with the image from the image projector to sequentially project an image in each of the three colors at a corresponding sub-pupil; providing an eyepiece having a plurality of waveguide layers; receiving sequentially images in each of the three colors in a corresponding waveguide layer to project a color image to a viewer; A method comprising: (Item 134) Item 134. The method of item 133, wherein the image projector is configured to sequentially project grayscale images at the optical pupil, each grayscale image configured to select a pixel for each of the three colors. (Item 135) Item 135. The method of item 134, wherein synchronizing the shutter with the color filter with the grayscale image includes projecting a single color image for a subpixel per grayscale image. (Item 136) Item 134. The method of item 133, wherein the image projector is configured to project a full-color image at the optical pupil. (Item 137) Item 137. The method of item 136, wherein synchronizing the shutter and color filter with the image from the image projector includes projecting three single color images for three corresponding sub-pixels per full color image from the image projector. [Brief explanation of the drawings]

[0011] The teachings of the embodiments disclosed herein can be readily understood by considering the following detailed description in conjunction with the accompanying drawings.

[0012] [Figure 1] FIG. 1 diagrammatically illustrates light paths within a viewing optical assembly (VOA) that may be used to present a digital or virtual image to a viewer, according to some embodiments.

[0013] [Figure 2] FIG. 2 is a schematic diagram illustrating an example of a projector, according to some embodiments.

[0014] [Figure 3] FIG. 3 is a schematic diagram illustrating an example of a projector, according to some embodiments.

[0015] [Figure 4] FIG. 4 is a schematic diagram illustrating multiple colors of light being coupled into corresponding waveguides using an internal coupling grating disposed within each waveguide, according to some embodiments.

[0016] [Figure 5] 5A-5C are top views of a distributed sub-pupil architecture, according to some embodiments.

[0017] [Figure 6] FIG. 6 is a schematic diagram illustrating time-sequential encoding of colors for multiple depth planes, according to some embodiments.

[0018] [Figure 7A] FIG. 7A is a schematic diagram illustrating a projector assembly, according to some embodiments.

[0019] [Figure 7B] FIG. 7B is an exploded schematic diagram illustrating the projector assembly shown in FIG. 7A.

[0020] [Figure 8A] FIG. 8A is a schematic diagram illustrating artifact formation resulting from reflections from internal coupling grating elements in a projection display system, according to some embodiments.

[0021] [Figure 8B]FIG. 8B is an exploded schematic diagram illustrating artifact formation resulting from reflections from an internal coupling grating in the projection display system shown in FIG. 8A.

[0022] [Figure 9] FIG. 9 is a schematic diagram illustrating reflections from an internal coupling grating, according to some embodiments.

[0023] [Figure 10A] FIG. 10A is a schematic diagram illustrating a projector assembly with artifact reduction using color filters, according to some embodiments.

[0024] [Figure 10B] FIG. 10B is an exploded schematic diagram illustrating the projector assembly shown in FIG. 10A.

[0025] [Figure 11A] FIG. 11A is a top view of a color filter used in conjunction with a distributed sub-pupil architecture, according to some embodiments.

[0026] [Figure 11B] FIG. 11B is a transmittance plot for red, green, and blue color filters according to some embodiments.

[0027] [Figure 11C] FIG. 11C is a top view of a color filter used in conjunction with a distributed sub-pupil architecture, according to some embodiments.

[0028] [Figure 12] FIG. 12 is a top view illustrating the spatial arrangement of color filters and sub-pupils, according to some embodiments.

[0029] [Figure 13] FIG. 13 is a cross-sectional view illustrating the integration of color filters and eyepiece waveguide layers, according to some embodiments.

[0030] [Figure 14A] FIG. 14A is a top view of a color filter used in conjunction with a subset of distributed sub-pupils, according to some embodiments.

[0031] [Figure 14B] FIG. 14B is a cross-sectional view illustrating the integration of the color filter and eyepiece waveguide layers shown in FIG. 14A according to some embodiments.

[0032] [Figure 14C] FIG. 14C is a top view of a color filter used in conjunction with another subset of dispersive sub-pupils, according to some embodiments.

[0033] [Figure 14D] FIG. 14D is a cross-sectional view illustrating the integration of the color filter and eyepiece waveguide layers shown in FIG. 14C, according to one embodiment.

[0034] [Figure 15] FIG. 15 is a top view of diffraction orders in a distributed sub-pupil architecture, according to some embodiments.

[0035] [Figure 16A] FIG. 16A is a side view of an eyepiece with an optical filter, according to some embodiments.

[0036] [Figure 16B] FIG. 16B is a plot illustrating the transmittance / reflectance curve of an optical filter, according to some embodiments.

[0037] [Figure 17A] FIG. 17A is a side view of an eyepiece with an absorbing color filter, according to some embodiments.

[0038] [Figure 17B]FIG. 17B is a plan view of the eyepiece shown in FIG. 17A.

[0039] [Figure 17C] FIG. 17C is a side view of an eyepiece with an absorbing color filter, according to some embodiments.

[0040] [Figure 18A] FIG. 18A is a side view of an eyepiece with aligned diffractive optical elements and optical filters, according to some embodiments.

[0041] [Figure 18B] FIG. 18B is a perspective view of the elements of the eyepiece illustrated in FIG. 18A.

[0042] [Figure 19] FIG. 19 is a side view of an eyepiece with an optical filter integrated into the eyepiece's waveguide, according to some embodiments.

[0043] [Figure 20] FIG. 20 is a perspective view of an eyepiece with a molded waveguide, according to some embodiments.

[0044] [Figure 21] FIG. 21 is a flowchart illustrating a method of operating an eyepiece including one or more planar waveguides, according to some embodiments.

[0045] [Figure 22] FIG. 22 is a flowchart illustrating a method of operating an eyepiece, according to some embodiments.

[0046] [Figure 23] FIG. 23 is a schematic diagram illustrating a side view of an eyepiece, according to some embodiments.

[0047] [Figure 24A]FIG. 24A is a schematic diagram illustrating an LCOS image projector according to some embodiments.

[0048] [Figure 24B] FIG. 24B is a schematic diagram illustrating the optical paths in a close-up view of the LCOS image projector in FIG. 24A, according to some embodiments.

[0049] [Figure 25] 25A-25B are simplified diagrams illustrating the positioning of LED light sources, according to some embodiments.

[0050] [Figure 26A] FIG. 26A is a schematic diagram illustrating an LED light source array, according to some embodiments.

[0051] [Figure 26B] FIG. 26B is a schematic diagram illustrating another LED light source array, according to some embodiments.

[0052] [Figure 26C] FIG. 26C is a schematic diagram illustrating yet another LED light source array, according to some embodiments.

[0053] [Figure 27-1] 27A-27D are schematic diagrams illustrating image display systems, according to some embodiments. [Figure 27-2] 27A-27D are schematic diagrams illustrating image display systems, according to some embodiments.

[0054] [Figure 28] FIG. 28 is a schematic diagram illustrating the behavior of image light coupled into a waveguide layer, according to some embodiments.

[0055] [Figure 29A]FIG. 29A is a photographic image illustrating higher order diffraction by LCOS in an image display system according to some embodiments.

[0056] [Figure 29B] 29B and 29C are schematic diagrams illustrating a method for arranging ICG in an image display system, according to some embodiments. [Figure 29C] 29B and 29C are schematic diagrams illustrating a method for arranging ICG in an image display system, according to some embodiments.

[0057] [Figure 30] FIG. 30 is a schematic diagram illustrating another image display system, according to some embodiments.

[0058] [Figure 31A] 31A-31C are schematic diagrams illustrating another image display system, according to some embodiments. [Figure 31B] 31A-31C are schematic diagrams illustrating another image display system, according to some embodiments. [Figure 31C] 31A-31C are schematic diagrams illustrating another image display system, according to some embodiments.

[0059] [Figure 32] FIG. 32 is a schematic diagram illustrating yet another image display system, according to some embodiments.

[0060] [Figure 33] FIG. 33 is a flowchart illustrating a method for displaying an image, according to some embodiments.

[0061] [Figure 34] FIG. 34 is a flowchart illustrating another method for displaying an image, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0062] The figures and the following description relate to various embodiments by way of example only. It should be noted that from the following discussion, alternative embodiments of the structures and methods disclosed herein will be readily recognized as viable alternatives that may be employed without departing from the principles discussed herein. Reference will now be made in detail to several embodiments, examples of which are illustrated in the accompanying figures.

[0063] FIG. 1 diagrammatically illustrates light paths within a viewing optical assembly (VOA) that may be used to present a digital or virtual image to a viewer, according to some embodiments. The VOA includes a projector 101 and an eyepiece 100 that may be worn around the viewer's eye 102. In some embodiments, the projector 101 may include a group of red LEDs, a group of green LEDs, and a group of blue LEDs. For example, the projector 101 may include two red LEDs, two green LEDs, and two blue LEDs. The eyepiece 100 may include one or more eyepiece layers. In some embodiments, the eyepiece 100 includes three eyepiece layers, one for each of three colors: red, green, and blue. In some embodiments, the eyepiece 100 may include six eyepiece layers: one set of eyepiece layers for three colors configured to form a virtual image at one depth plane, and another set of eyepiece layers for three colors configured to form a virtual image at another depth plane. In some embodiments, the eyepiece 100 may include three or more eyepiece layers for three colors each, for three or more different depth planes. Each eyepiece layer may include a planar waveguide and may include an internal coupling grating 107, an orthogonal pupil expander (OPE) region 108, and an exit pupil expander (EPE) region 109.

[0064] Still referring to FIG. 1 , the projector 101 projects image light onto an internal coupling grating 107 in the eyepiece layer. The internal coupling grating 107 couples the image light from the projector 101 into a planar waveguide, causing the image light to propagate in a direction toward the OPE region 108. The planar waveguide propagates the image light horizontally by total internal reflection (TIR). The OPE region 108 of the eyepiece layer includes a diffractive element that couples and redirects a portion of the image light propagating in the waveguide toward the EPE region 109. The EPE region 109 includes a diffractive element that couples and directs a portion of the image light propagating in the planar waveguide toward the viewer's eye 102 in a direction generally perpendicular to the plane of the eyepiece layer. In this manner, the image projected by the projector 101 can be viewed by the viewer's eye 102.

[0065] As described above, the image light generated by the projector may include light in three colors: blue (B), green (G), and red (R). Such image light can be separated into its constituent colors so that the image light in each constituent color can be coupled into a separate waveguide within the eyepiece.

[0066] FIG. 2 is a schematic diagram illustrating a projector according to some embodiments. Projector 200 includes a set of spatially displaced light sources 205 (e.g., LEDs, lasers, etc.) positioned in specific orientations with a predetermined distribution, for example, as discussed below in connection with FIGS. 5A-5C . Light sources 205 can be used alone or in conjunction with a sub-pupil forming a collection optic, such as a light pipe or mirror, to collect more light and form a sub-pupil at the end of the light pipe or collection mirror. For clarity, only three light sources are illustrated. In some embodiments, quasi-collimation optics 225 are utilized to collimate the light emitted from light source 205 to some extent, so that the light enters polarizing beam splitter (PBS) 210 in a more collimated manner, and more light reaches display panel 207. In other embodiments, a collimating element (not shown) is utilized to collimate the light emitted from light source 205 after propagating through portions of PBS 210. In some embodiments, a pre-polarizer may be present between the quasi-collimating optics 225 and the PBS 210 to polarize the light entering the PBS 210. The pre-polarizer may also be used to recycle a portion of the light. Light entering the PBS 210 reflects and impinges onto the display panel 207, where the scene is formed. In some embodiments, a time-sequential color display can be used to form the color image.

[0067] Light reflected from the display panel 207 passes through the PBS 210 and is focused using a projector lens 215, also referred to as imaging optics or a set of imaging optics, to form an image of the scene at a distance. The projector lens 215 roughly forms a Fourier transform of the display panel 207 on or in the eyepiece 220. The projector 200 provides a sub-pupil in the eyepiece 220 that is an inverted image of the sub-pupil formed by the light source 205 and collection optics. As shown in FIG. 2 , the eyepiece 220 includes multiple layers. For example, the eyepiece 220 includes six layers or waveguides, each associated with a color (e.g., three colors) and a depth plane (e.g., two depth planes per color). "Switching" between color and depth layers is accomplished by switching which light source 205 is turned on. As a result, no shutters or switches are utilized to switch between colors and depth planes in the illustrated system.

[0068] Additional discussion related to projector 200 and variations on the architecture of projector 200 is discussed herein.

[0069] FIG. 3 is a schematic diagram illustrating a projector according to some embodiments. FIG. 2 illustrates projector 300. Display panel 320 is a liquid crystal on silicon (LCOS) panel, although the present disclosure is not limited to this implementation. Other display panels, including front-illuminated LCOS (FLCOS), DLP, and the like, may also be utilized. In some embodiments, a color-sequential LCOS design is utilized, as discussed in connection with the time-sequential encoding discussed in connection with FIG. 6, although other designs in which all colors (e.g., RGB) are displayed in parallel can also be implemented. As color filter performance improves and pixel size decreases, system performance improves, and embodiments of the present disclosure will benefit from such improvements. Accordingly, several reflective or transmissive display panels can be utilized in conjunction with the distributed sub-pupil architecture disclosed herein. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0070] In some embodiments, light emitted by light source 310 and polarized by pre-polarizer 325, including focusing optics, propagates through polarizing beam splitter (PBS) 330, passes through quarter-wave plate 327, and impinges on collimator 332, which may be implemented, for example, as a mirror lens, a reflective lens, or a curved reflector. The spatial separation between light sources 310 enables a distributed sub-pupil architecture. Collimator 332, which in some embodiments is a reflective collimator, collimates or focuses the light emitted by light source 310 to some extent and directs the collimated light back into PBS 330, through quarter-wave plate 327, with the polarization state changed to direct the light onto display panel 320.

[0071] As the collimated light propagates through the PBS 330, it is reflected at interface 331 and directed toward the display panel 320. Interface 331 can be implemented using polarizing films, wire grid polarizers, dielectric stack coatings, combinations thereof, and the like. The display panel 320 forms a scene or series of scenes that can then be imaged onto the eyepiece. In some embodiments, time-sequential image formation for different colors and depth planes is accomplished by sequentially operating the light source 310 in conjunction with the operation of the display panel 320. In some embodiments, compensation elements are installed in the PBS 330 or attached to the display panel 320 to improve the performance of the display panel 320. After reflecting from the display panel 320, the light enters the PBS 330 at side 303, propagates through interface 331, and exits the PBS 330 at side 304. An optical lens 340, also referred to as a projector lens 340, is then utilized to form the Fourier transform of the display and, in conjunction with a collimator 332, form an inverted image of the sub-pupil of the light source 310 at or within the eyepiece.

[0072] According to some embodiments, a projector assembly is provided. The projector assembly includes a PBS (e.g., PBS 330). The projector assembly also includes a set of spatially displaced light sources (e.g., light sources 310) adjacent to the PBS 330. The light sources 310 can be different color LEDs, lasers, or the like. In some embodiments, the light sources 310 are adjacent to a first side 301 of the PBS 330. The PBS 330 passes light emitted by the light sources 310 during a first pass.

[0073] A collimator 332, which may be a reflective mirror, is positioned adjacent to the PBS 330 to receive the light and provide a first pass through the PBS 330. The collimator 332 is adjacent to a second side 302 of the PBS 330 opposite the first side 301 adjacent the light source 310. The collimator 332 collimates and focuses the emitted light and directs the collimated light back into the second side 302 of the PBS 330.

[0074] The projector assembly also includes a display panel 320 adjacent to a third side 303 of the PBS 330, which is positioned between the first side 301 and the second side 302. The display panel 320 can be an LCOS panel. During the second pass through the PBS 330, the collimated light reflects from an interface 331 within the PBS 330 and is directed toward the display panel 320 due to the change in its polarization state caused by passing twice through the double quarter-wave plate 327.

[0075] The projector assembly further includes a projector lens 340 adjacent to a fourth side 304 of the PBS 330, which is positioned between the first side 301 and the second side 302 and opposite the third side 303. The location of the projector lens 340 between the PBS 330 and the final image formed by the projection display assembly indicates that the illustrated system utilizes the PBS 330 at the rear of the projector assembly.

[0076] The projector assembly forms an image of the sub-pupil and the Fourier transform of the display panel 320 at an image location. An internal coupling interface with the eyepiece is positioned near the image location. Because the light emitted by the light sources 310 propagates through different paths within the projector assembly, the images associated with each light source of the light sources 310 are spatially displaced in the image plane of the system, allowing them to be coupled into different waveguides that make up the eyepiece.

[0077] 4 is a schematic diagram illustrating multiple colors of light being coupled into corresponding waveguides using internal coupling elements disposed within each waveguide, according to some embodiments. A first waveguide 410, a second waveguide 420, and a third waveguide 430 are positioned adjacent to each other in a parallel arrangement. In one example, the first waveguide 410 can be designed to receive and propagate light within a first wavelength range 401 (e.g., red wavelengths), the second waveguide 420 can be designed to receive and propagate light within a second wavelength range 402 (e.g., green wavelengths), and the third waveguide 430 can be designed to receive and propagate light within a third wavelength range 403 (e.g., blue wavelengths).

[0078] Light in all three wavelength ranges 401, 402, and 403 is focused onto approximately the same plane due to the Fourier transform refractive power of the projector lens 440, but is displaced in the plane, roughly due to the spacing of the sub-pupils in the optical module and the magnification of the optical system, if applicable. Internal coupling elements 412, 422, and 432 of the respective waveguides 410, 420, and 430 are placed in the paths corresponding to the correct color sub-pupils to capture and couple a portion of the light into the respective waveguides 410, 420, and 430.

[0079] The incoupling elements 412, 422, and 432, which may be incoupling gratings, can be elements of an incoupling diffractive optical element (DOE). When a given light source is turned on, light from that light source is imaged to the corresponding plane (e.g., for red LED #1, the first waveguide 410 at the first depth plane). This allows switching between colors by simply switching the light source off and on.

[0080] To reduce the occurrence and / or effects of artifacts, also referred to as afterimages or other reflections, some embodiments of the present disclosure utilize absorptive color filters, which may be used in single-pupil systems.

[0081] 5A-5C are top views of a distributed sub-pupil architecture according to some embodiments. The distributed sub-pupils can be associated with different light sources (e.g., LEDs or lasers) operating at different wavelengths and different positions (i.e., different lateral positions). Referring to FIG. 5A, this first arrangement has six sub-pupils associated with two depth planes and three colors per depth plane. For example, two sub-pupils 510 and 512 are associated with a first color (e.g., a red sub-pupil), two sub-pupils 514 and 516 are associated with a second color (e.g., a green sub-pupil), and two sub-pupils 518 and 520 are associated with a third color (e.g., a blue sub-pupil). These sub-pupils correspond to six light sources that are spatially offset in the emission plane. The illustrated six sub-pupil embodiment may be suitable for use in a three-color, two-depth plane architecture. Additional description related to distributed sub-pupil architectures is provided in U.S. Patent Application Publication No. 2016 / 032773, published November 10, 2016, the disclosure of which is incorporated by reference herein in its entirety for all purposes.

[0082] As an example, if two light sources are positioned opposite each other with respect to the optical axis (i.e., opposite around the optical axis), it is possible that light from one of the light sources (i.e., the first light source) propagates through the optical system, reflects off the eyepiece, e.g., the eyepiece's internal coupling grating or other surface, propagates back through the optical system, and then reflects again at the display panel, reappearing at a location opposite the original light source image with respect to the optical axis. This double reflection, appearing at a different sub-pupil location, would create a residual image because the light was originally emitted by the first light source. Thus, in the arrangement shown in FIG. 5A , sub-pupils 510 / 512, 514 / 516, and 518 / 520 are not positioned opposite each other with respect to the optical axis and the center of the sub-pupil distribution, so light from these sets of sub-pupils will not be coupled into other sub-pupils in the set after propagating through the optical system. Therefore, this sub-pupil layout partially prevents artifact formation, also known as residual image formation.

[0083] In FIG. 5A , the color and depth planes associated with each sub-pupil are illustrated as follows: red wavelengths: R1 / R2 at the first and second depth planes, green wavelengths: G1 / G2 at the first and second depth planes, and blue wavelengths: B1 / B2 at the first and second depth planes. Diffractive optical elements can be placed at these sub-pupil locations, as discussed in connection with FIG. 4 . While diffraction gratings, referred to as internal coupling gratings, are discussed herein, embodiments of the present disclosure are not limited to diffraction gratings; other diffractive optical elements can also be utilized, including binary diffractive elements, stepped diffractive elements, and other suitable diffraction-based structures. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0084] Referring to FIG. 5B , a nine-sub-pupil embodiment is illustrated that would be suitable for use in a three-color, three-depth plane architecture. In this embodiment, a first set of sub-pupils, including sub-pupils 540, 542, and 544 associated with a first color (e.g., red sub-pupils), are positioned 120° relative to each other. A second set of sub-pupils, including sub-pupils 550, 552, and 554 associated with a second color (e.g., green), are positioned 120° relative to each other, and their distribution is rotated 60° from the first set of sub-pupils. Thus, when light from sub-pupil 440 is reflected within the system and re-emerges at sub-pupil 554 opposite sub-pupil 540, there will be no color overlap. A third set of sub-pupils, including sub-pupils 560, 562, and 564 associated with a third color (e.g., blue), are positioned inside the distributions of the first and second sub-pupils and are positioned at 120° relative to each other.

[0085] FIG. 5C illustrates six sub-pupil arrangements, with sub-pupils 570 and 572 associated with a first color (e.g., red) positioned at two corners of the sub-pupil distribution, sub-pupils 580 and 582 associated with a second color (e.g., green) positioned at the other two corners of the sub-pupil distribution, and sub-pupils 590 and 592 associated with a third color (e.g., blue) positioned along the sides of the rectangular sub-pupil distribution. Thus, sub-pupil arrangements such as those illustrated in FIGS. 5B-5C can be utilized to reduce the effects of residual images. Alternative sub-pupil arrangements may also be utilized, such as sub-pupil arrangements in which sub-pupils of different colors are opposite each other across the optical axis. Residual images can be reduced by using color-selective elements (e.g., color-selective rotators) or color filters in each individual internal coupling grating.

[0086] Figure 6 is a schematic diagram illustrating time-sequential encoding of colors for multiple depth planes, according to some embodiments. As shown in Figure 6, depth planes (three in this example) are least significant bit (LSB) encoded per pixel via shaders. The projector assembly discussed herein provides precise placement of pixels per color at the desired depth plane. Three colors are sequentially encoded per depth plane: (R0, G0, B0 for plane 0) 602, (R1, G1, B1 for plane 1) 604, and (R2, G2, B2 for plane 2) 606. Illumination of each color over 1.39 ms provides an illumination frame rate 608 of 720 Hz and a frame rate for all three colors and three depth planes 610 of 80 Hz (based on 12.5 ms to refresh all colors and planes). In some embodiments, a single color for a single depth plane per frame may be used by using only the light source associated with a particular color for that particular depth plane.

[0087] In some embodiments, multiple depth planes can be implemented through the use of variable focus lenses that receive sequentially coded colors. In these embodiments, there may be three eyepiece lens layers, and the internal coupling gratings may be further spaced apart so that they are not positioned directly across from each other about the optical axis. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0088] FIG. 7A is a schematic diagram illustrating a projector assembly according to some embodiments. FIG. 7B is an exploded schematic diagram illustrating the projector assembly shown in FIG. 7A. As shown in FIG. 7A, the projector architecture 700 includes an illumination source 710, which can emit a set of collimated light beams, such as a laser. In this embodiment, the light from the illumination source 710 is already collimated, so a collimator can be omitted from the optical design. The illumination source 710 can emit polarized, unpolarized, or partially polarized light. In the illustrated embodiment, the illumination source 710 emits light 712 polarized with p-polarized light. A first optical element 715 (e.g., a pre-polarizer) is aligned to pass light with p-polarized light to a polarizing beam splitter (PBS) 720. The light first passes through an interface 722 (e.g., a polarization interface) of the PBS 720 and impinges on a spatial light modulator (SLM) 730. The SLM 730, also referred to as a display panel, provides spatial modulation on light to produce an image. In the on state, the SLM 730 modulates input light from a first polarization state (e.g., a p-polarization state) to a second polarization state (e.g., an s-polarization state) to indicate a bright state (e.g., a white pixel). The second polarization state may be a 90° modulation (e.g., a shift) of the first polarization state. In the on state, light having the second polarization state is reflected by the interface 722 and travels downstream to the projector lens 740. In the off state, the SLM 730 does not rotate the input light from the first polarization state, thus indicating a dark state (e.g., a black pixel). In the off state, light having the first polarization state is transmitted through the interface 722 and travels upstream to the illumination source 710. In intermediate states, the SLM 730 modulates the input light from the first polarization to an elliptical polarization state. In the intermediate state, a portion of the light having an elliptical polarization state (e.g., p-polarization state) is transmitted through interface 722 and travels upstream toward illumination source 710, and a portion of the light having an elliptical polarization state (e.g., s-polarization state) is reflected by interface 722 and travels downstream toward projector lens 740.

[0089] After reflecting from the SLM 730, the reflected light 714 reflects from interface 722 and exits the PBS 720. The emitted light passes through a projector lens 740 and is imaged onto an internal coupling grating 750 in the eyepiece (not shown).

[0090] Figure 7B illustrates the imaging of light associated with a first sub-pupil 711 of an illumination source 710 onto an internal coupling grating 750 of an eyepiece. The light associated with the first sub-pupil is collected before entering the PBS 720, reflects off the SLM 730, enters the PBS 720, reflects off an interface 722 (not shown), exits the PBS 720, passes through a projector lens 740, and is relayed onto the internal coupling grating 750. An optical axis 705 is illustrated in Figure 7B.

[0091] 8A is a schematic diagram illustrating artifact formation resulting from reflections from the internal coupling grating or substrate surface of an eyepiece in a projection display system according to some embodiments. FIG. 8B is an exploded schematic diagram illustrating artifact formation resulting from reflections from the internal coupling grating or substrate surface of an eyepiece in the projection display system shown in FIG. 8A. In some embodiments, the projector assembly 800 shown in FIG. 8A may include a circular polarizer between the PBS 720 and the projector lens 740.

[0092] 8A, in a manner similar to the operation of projector assembly 700 in FIG. 7A, light 802 with an s-polarization state from SLM 730, also referred to as the display panel, is reflected at inner interface 722 of PBS 720. Note that the tilt of the light rays after reflection from interface 722 is provided solely for purposes of clarity. Most of the light emitted from PBS 720 passes through and is relayed by projector lens 740 to provide an image of the sub-pupil to internal coupling grating 750 of the eyepiece.

[0093] A portion of the light incident on the internal coupling grating 750 is reflected by the internal coupling grating 750. As illustrated in FIG. 8A, the light incident on the internal coupling grating 750 can be in a single polarization state (e.g., s-polarization state), while the light reflected from the internal coupling grating 750 can be in a mixture of polarization states (A * s+B * p) 804, where A and B are coefficients between 0 and 1. For a diffractive optical internal coupling grating with steps in the plane of the eyepiece, the reflection is primarily inverted circular polarization. However, if the internal coupling grating steps are tilted out of the plane of the eyepiece, other polarization states will also be reflected. As the reflected light 804 passes through the projector lens 740 and propagates back towards the PBS 720, it will have a mixture of polarizations (C * s+D * p) 806, where C and D are coefficients between 0 and 1. Generally, A>C and B>D as a result of the properties of the internal coupling grating 750 and / or projector lens 740.

[0094] Polarization of the interface (C * Light in the upstream path, properly aligned with the SLM 730, reflects off the interface 722, passes through the SLM 730, and is imaged by the projector lens 740 into a single polarization state (E * s) 812 to a second internal coupling grating 752 in the eyepiece. Because the light source in both internal coupling gratings 750 and 752 is the same, the light in internal coupling grating 752 appears as it does within SLM 730, thereby producing artifacts or residual images.

[0095] Referring to FIG. 8B, symmetry around the optical axis 705 is demonstrated by the imaging at the internal coupling grating 750 after the first pass through the PBS 720 and projector lens 740, and by the imaging at the internal coupling grating 752 after the reflected light 804 is reflected from the SLM 730.

[0096] FIG. 9 is a schematic diagram illustrating reflections from an internal coupling grating, according to some embodiments. The eyepiece can include a cover glass 910 and an internal coupling grating 920. The incident light is illustrated as left-handed circularly polarized (LHCP) input light 901. While input light with circular polarization is illustrated, embodiments of the present disclosure are not limited to circular polarization; the input light can also be elliptically polarized with predetermined major and minor axes. Reflections from the eyepiece can include a reflection 903 from a front surface 912 of the cover glass 910 and a reflection 905 from a back surface 914 of the cover glass 910. In addition, a reflection 907 from the internal coupling grating 920 is also illustrated. In this example, reflections 903 and 905 are right-handed circularly polarized (RHCP), and reflection 907 is LHCP. The sum of these reflections results in a mixed polarization state propagating upstream toward the PBS 720. Thus, in FIG. 8A , the reflections from the internal coupling grating 750 are A * s+B * Although illustrated as p, it will be apparent to one skilled in the art that the polarization state of the reflected light is not limited to combinations of linear polarizations and can include elliptical polarizations as well. In particular, when the diffractive elements of the internal coupling grating 750 include blazed grating features, the polarization state of the reflected light is characterized by complex elliptical polarizations. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0097] 10A is a schematic diagram illustrating a projector assembly with artifact reduction using color filters, according to some embodiments. The projector assembly illustrated in FIG. 10A shares some common elements with the projector assembly illustrated in FIG. 8A, and the description provided in FIG. 8A is applicable to the projector assembly in FIG. 10A, as appropriate. As described herein, a color filter with spectral properties selected based on the spectral properties of the internal coupling grating is positioned adjacent to the internal coupling grating to block light with substantially different spectral characteristics from being incoupling into the internal coupling grating. As illustrated in FIG. 10A, embodiments of the present disclosure reduce optical artifacts resulting from specular reflections associated with the operation of reflective display projectors, slab waveguides, and / or internally coupled diffractive optical elements.

[0098] The projector assembly with artifact prevention 1000 includes an illumination source 1010, which can emit a set of collimated light beams, such as a laser. The illumination source 1010 can emit polarized, unpolarized, or partially polarized light. In the illustrated embodiment, the illumination source 1010 emits light polarized with p-polarized light. A first optical element 1015 (e.g., a pre-polarizer) is aligned to pass the light with p-polarized light to a polarizing beam splitter (PBS) 1020. The light first passes through an interface 1022 of the PBS 1020 and impinges on a spatial light modulator (SLM) 1030. The SLM 1030, also referred to as a display panel, imparts spatial modulation to the light to provide an image. After reflection from the SLM 1030 and a change in polarization to s-polarized light, the reflected light reflects from the interface 1022 and exits the PBS 1020. The emitted light passes through a projector lens 1040 and is imaged onto an internal coupling grating 1050 in an eyepiece (not shown).

[0099] Although only two internal coupling gratings 1050 and 1052 are illustrated in FIG. 10A , embodiments of the present disclosure are not limited to this number, and other numbers of internal coupling gratings can be utilized, such as six internal coupling gratings for two depth planes and three colors (e.g., red, green, and blue). Thus, for example, if green light is specularly reflected from the internal coupling grating 1050, this light will traverse the optical system and be blocked when a filter 1072 that attenuates green light, such as a red or blue color filter, which may be referred to as a green blocking filter, is positioned adjacent to the internal coupling grating 1052, thereby reducing the inverted afterimage. In addition, although the internal coupling gratings 1050 and 1052 are illustrated in FIG. 10A , embodiments of the present disclosure are applicable to other structures that reflect light into the optical system, ultimately resulting in the reflected light retracing its course and propagating toward the structure that produced the reflection. It should be noted that while some filters are illustrated as passing a first set of one or more colors and attenuating a second set of one or more other colors, other embodiments may pass a first set of one or more colors (e.g., passing blue and green) and attenuate a second set of one or more colors (e.g., red). For example, in one embodiment, a filter may pass green and attenuate blue and red. For example, in one embodiment, a filter may pass blue and red light and attenuate green light.

[0100] A portion of the incident light will reflect from the internal coupling grating 1050 and propagate back towards the projector lens 1040. As illustrated in FIG. 10A, the light incident on the internal coupling grating 1050 can be in a single polarization (e.g., s-polarized), while the light reflected from the internal coupling grating 1050 can be in a mixture of polarizations (A * s+B * p) 1062, where A and B are coefficients between 0 and 1. As the reflected light passes through the projector lens 1040 and propagates back towards the PBS 1020, it becomes a mixture of polarizations (C * s+D *p) 1064, where C and D are coefficients between 0 and 1. Generally, A>C and B>D as a result of the properties of the projector lens 1040.

[0101] Polarization of the interface (C * Light in the upstream path, properly aligned with the SLM 1066 , passes through the interface 1022 , the SLM 1030 , reflects from the interface 1022 , and passes through the projector lens 1040 .

[0102] Spectral filters (e.g., absorptive optical filters) are placed in the optical path between the projector lens 1040 and the internal coupling gratings 1050 and 1052 of the eyepiece. For example, as illustrated in FIG. 11A , the spectral filters are patterned to overlap the incident light paths for the corresponding internal coupling gratings. The spectral filters may be reflective (e.g., dielectric coatings) and / or absorptive. Absorptive filters may be fabricated with inks, dyes, acrylics, photoresists, or using techniques such as retarder filter stacks. The spaces between the spectral filters may be coated with an absorptive (e.g., black) material for further artifact reduction. As examples, Dimatix UV-curable inks available from Kao Collins, Inc. (Cincinnati, OH) and INXFlex® UV flexographic inks and INXCure® UV / EB inks available from INX International Ink Co. (Schaumberg, IL) can be utilized in accordance with embodiments of the present disclosure.

[0103] Referring back to FIG. 10A , absorbing color filters 1070 and 1072 are positioned adjacent to the internal coupling gratings 1050 and 1052, respectively. Thus, the absorbing color filter 1070 is inserted in the optical path between the projector lens 1040 and the internal coupling grating 1050. Similarly, the absorbing color filter 1072 is inserted in the optical path between the projector lens 1040 and the internal coupling grating 1052. Although FIG. 10A illustrates the color filters 1070 and 1072 positioned adjacent to the internal coupling gratings 1050 and 1052, the color filters 1070 and 1072 can be positioned in other locations between the projector lens 1040 and the internal coupling gratings 1050 and 1052. Preferably, the color filters 1070 and 1072 are positioned near the beam focal points so that the color filters 1070 and 1072 can be physically separated and located in distinctly different areas. The placement of color filters 1070, 1072 in the optical path upstream of the internal coupling gratings 1050, 1052 allows reflected light to be blocked or attenuated, regardless of whether the color filters 1070, 1072 are arranged as an array in a single plane or in different planes.

[0104] In the absence of color filters 1070, 1072, light (E * s) 1068 will be imaged onto the second internal coupling grating 1052 in the eyepiece. However, the presence of the color filter 1072 attenuates or eliminates the image at the second internal coupling grating 1052 from reflection from the internal coupling grating 1052, thereby reducing or preventing the formation of artifacts or afterimage images.

[0105] Figure 10B is an exploded schematic diagram illustrating the projector assembly shown in Figure 10A. Light from illumination source 1010 is collimated by first optical element 1015, propagates through PBS 1020, reflects off SLM 1030, passes through PBS 1020 again, reflects off interface 1022 (not shown), and passes through projector lens 1040. Light in the downstream path passes through color filter 1070 and is imaged onto internal coupling grating 1050.

[0106] The reflected light passes through color filter 1070, passes through projector lens 1040, passes through PBS 1020, reflects from interface 1022 (not shown), and reflects from SLM 1030. The light passes through PBS 1020, reflects from interface 1022, propagates in a downstream path through projector lens 1040, and is blocked or attenuated by color filter 1072.

[0107] The spectrally diverse nature of the color filter set allows the blue / green / red image addressed to a corresponding sub-pupil to pass through the blue / green / red filter implemented in that location, while blocking higher diffraction order blue / green / red images from entering other sub-pupils. Light diffracted from the SLM 1030 that impinges between the sub-pupils is absorbed by the dark or black matrix surrounding the sub-pupil, thus improving contrast in the final image.

[0108] As illustrated in FIG. 11A, one possible layout for the color filters is shown. Generally, a set of design rules can be followed when defining the color filter layout. For high efficiency in a small package, it is desirable to have all zero-order images projected within the upper pupil 1110. In some embodiments, it is also preferable to have complementary color filters (i.e., color filters that do not have the same spectral band) symmetrically opposed across the optical axis to prevent zero-order specular reflections from entering the image through an internal coupling grating positioned across the optical axis that is operable to diffract light within the spectral band. In some embodiments, it is preferable to minimize the overlap area between one type of higher-order color image and a different lower pupil of the same color. This will be discussed in more detail in connection with FIG. 15. If the transmittance profiles for different color filters have overlapping regions in the spectrum (e.g., a green filter transmits some light at 500 nm, while a blue filter also has some finite transmittance at 500 nm), it is preferable to position the filters and internal coupling gratings so that higher-order green images and higher-order blue images overlap as little as possible within the upper pupil 1110 as spectrally adjacent color lower pupils. For higher optical efficiency, the size of the color filters should be large enough to pass a significant portion (e.g., >90%) of the beam energy. Color filters may also be used in conjunction with optical isolators such as circular polarizers to further improve artifact reduction. The color filters and / or the surrounding glass substrate can be coated with an anti-reflective optical layer to improve optical efficiency, further improve image contrast, and reduce image retention. An absorbing material in the area between the lower pupils can block stray light from entering the eyepiece lens layer.

[0109] FIG. 11B is a transmittance plot for red, green, and blue color filters according to some embodiments. The transmittance spectra of the color filters are selected to produce high transmittance values ​​within the spectral bands and little or minimal overlap in the transmittance spectra between two spectrally adjacent color filters. As an example, embodiments can be implemented to provide a predetermined minimum overlap between spectrally adjacent colors, where blue / green and green / red are spectrally adjacent. As an example, the spectral overlap between adjacent colors can be a predetermined percentage of the peak transmittance value. For example, the transmittance value at the wavelength where the adjacent spectra overlap may be less than 10% of the maximum transmittance value.

[0110] 11B, color filters B1 / B2 are characterized by high transmittance (e.g., 80%) at the peak of the spectral band, which may be aligned with the wavelength of the corresponding light source, and minimal spectral overlap with spectrally adjacent color filters G1 / G2. As illustrated in FIG. 11B, the minimal overlap may be, for example, less than 10% at a wavelength and / or the filter overlap may be less than 10% at the intersection of the two spectra.

[0111] Generally, color filters with Gaussian transmittance profiles can be utilized, but high-pass or low-pass filters can also be used for the color filters. As an example, in FIG. 11B, color filters R1 / R2 are high-pass filters with high transmittance at wavelengths above about 550 nm and low transmittance at wavelengths below about 550 nm. Note that the transmittance profile for color filters R1 / R2 increases at wavelengths below about 450 nm, but the internal coupling grating for the waveguide supporting green wavelengths is characterized by poor diffraction efficiency for red wavelengths.

[0112] 11C is a top view of color filters used in conjunction with a distributed sub-pupil architecture, according to some embodiments. In this embodiment, two sets of spectrally adjacent colors are opposite each other across the optical axis 1105: G2 / R1 and B2 / G1. Note that R2 / B1 are not spectrally adjacent colors.

[0113] FIG. 12 is a top view illustrating the spatial arrangement of color filters and sub-pupils according to some embodiments. In this embodiment, both the color filters and the internal coupling gratings (IGR1 / IGR2: IGG1 / IGG2: IGB1 / IGB2) for the waveguides supporting the corresponding wavelengths are shown shaped as portions of a circle. An embodiment is provided in which the color filters overlap more than one sub-pupil. It should be understood that the color filters are positioned in more than one plane extending outside the plane of the figure, and the internal coupling gratings are positioned in a plane extending within the plane of the figure. The optical axis 1105 is located at the intersection of the color filters in this embodiment.

[0114] FIG. 13 is a cross-sectional view illustrating the integration of color filters and eyepiece waveguide layers, according to some embodiments. In some embodiments, the color filters can be placed in a single plane between the projection lens 1040 and the internal coupling gratings 1050 / 1052, as illustrated in FIG. 10A. In some embodiments, the color filters can be placed between the waveguide layers of the eyepiece, as illustrated in FIG. 13. In this embodiment, the eyepiece is illustrated with three waveguide layers 1310, 1320, and 1330, which can be associated with three different colors, namely, green, blue, and red, respectively. Light incident on the red internal coupling grating 1332 passes through a red color filter 1334, which is positioned (e.g., printed) on the back surface of the waveguide layer 1320. As the light propagates toward the internal coupling grating 1332, it passes through the waveguide layers 1310 and 1320. Wavelengths of light outside the transmission band of the red color filter 1334 are blocked or attenuated by the red color filter 1334. With reference to Figure 13, the position of the color filter measured along the x- and y-axes (i.e., xy position) may be referred to as the lateral position. The position of the color filter relative to the cover glass (i.e., cover plate) 1305 measured along the z-axis (i.e., z position) may be referred to as the longitudinal position.

[0115] Similarly, for other colors, light incident on the blue in-coupling grating 1322 passes through a blue color filter 1324 positioned (e.g., printed) on the back surface of the waveguide layer 1310. As the light propagates toward the blue in-coupling grating 1322, it passes through the waveguide layer 1310. Wavelengths of light outside the transmission band of the blue color filter 1324 are blocked or attenuated by the blue color filter 1324.

[0116] Because the green in-coupling grating 1312 is disposed on the first waveguide layer 1310, a color filter for green wavelengths is not utilized in this embodiment; however, a green color filter can be implemented between the projection lens and the green in-coupling grating 1312, for example, printed on the front surface of the waveguide layer 1310, or printed on the cover glass 1305 adjacent to the waveguide layer 1310. It should be understood that the color filter can be implemented on multiple surfaces, including the front and / or back sides of the cover glass, the front and / or back sides of the waveguide layer, and combinations thereof. In some embodiments, the color filter can be implemented (e.g., printed) on the projector lens (e.g., projector lens 340). For example, the color filter can be printed on the eyepiece, particularly on an element or surface of the projector lens 340 closest to the in-coupling grating. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0117] In alternative embodiments, additional color filters can be added to increase the attenuation of colors outside the filter's spectral band. For example, an optional (e.g., red) filter 1336 may be positioned on the back surface of the waveguide layer 1310 to provide additional attenuation of blue and green artifacts. Furthermore, such additional filters can have different spectral properties than the corresponding filters. As an example, optional filter 1336 can be a "yellow" filter that blocks blue wavelengths. Note that while uniform thickness color filters are illustrated in FIG. 13, color filters that may be of different thicknesses can also be utilized to achieve desired absorption properties. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0118] FIG. 14A is a top view of color filters used with a subset of distributed sub-pupils, according to some embodiments. In this top view, four color filters R1, R2, G1, and B1 are shown. In this implementation, color filters for light intended for the second green and blue depth planes (B2 and G2) are optional and are represented by dashed lines. As shown, the color filters in this sub-pupil layout are arranged such that opposing color filters, represented by lines 1410, are oriented between the opposing color filters to attenuate light propagating through the optical system after reflecting from the internal coupling grating. Light reflected from the internal coupling grating adjacent to optional color filter G2 couples to opposing color filter R1. Similarly, light reflected from the internal coupling grating adjacent to optional color filter B2 couples to opposing color filter R2. Light reflected from the internal coupling grating adjacent to color filters G1 and B1 couples to opposing color filters (B1 and G1). As shown, filters that pass the same color are not positioned opposite each other across the optical axis. Thus, G1 and B1 are opposed, and R1 and R2 are adjacent to each other. Therefore, if green light passing through the internal coupling grating for green is reflected through the optical system and impinges on blue color filter B1, this green light will be attenuated by blue color filter B1.

[0119] FIG. 14B is a cross-sectional view illustrating the integration of the color filters and eyepiece waveguide layers shown in FIG. 14A according to some embodiments. In this cross-sectional view, the color filter layout in the top view is superimposed for clarity. Only color filters R2 and B1 are shown in the cross-sectional view because they are closest to the foreground surface of the eyepiece, but it should be understood that color filters R1 and G1 are also present, but in positions extending into the plane of the figure. In this embodiment, the color filters are disposed on the back surface of the cover glass 1430, but they can be positioned elsewhere. The color filters can have a thickness equal to the gap between adjacent waveguide layers. An additional cover glass 1432 is also shown. Preferably, an index-matched, highly transparent adhesive 1440 is utilized between the waveguide layers to reduce Fresnel reflections as light propagates through the waveguide layers.

[0120] Light intended for the red waveguide layer 1450 is incident on the internal coupling grating 1452, where it passes through red color filter R2 and other waveguide layers until it is diffracted into the plane of the waveguide layer 1450. Light intended for the blue waveguide layer 1460 is incident on the internal coupling grating 1462, where it passes through blue color filter B1 and other waveguide layers until it is diffracted into the plane of the waveguide layer 1460. In this embodiment, the low coupling efficiency of red light into the blue and green internal coupling gratings allows for a design in which color filters are not positioned adjacent to these internal coupling gratings, as represented by the optional G2 / B2 color filters.

[0121] 14C is a top view of color filters used with another subset of dispersed sub-pupils, according to some embodiments. In this embodiment, spectrally adjacent colors are positioned opposite each other (G1 / B1 and R1 / G2). The B2 color filter is not utilized in this implementation because the red and blue wavelengths are at opposite ends of the optical spectrum, resulting in low efficiency of incoupling red light through the blue incoupling grating. In other embodiments, six filters are utilized, including a B2 filter opposite an R2 filter. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0122] FIG. 14D is a cross-sectional view illustrating the integration of the color filters and eyepiece waveguide layers shown in FIG. 14C according to some embodiments. In this cross-sectional view, the color filter layout in the top view is superimposed for clarity. Only color filters R2, B1, and G2 are shown in the cross-sectional view because they are closest to the foreground surface of the eyepiece, but it should be understood that color filters R1 and G1 are also present, but in positions extending into the plane of the figure. In this embodiment, the color filters are disposed on the back surface of cover glass 1430, but they can be positioned elsewhere. The color filters can have a thickness equal to the gap between adjacent waveguide layers. An additional cover glass 1432 is also shown.

[0123] Light intended for the red waveguide layer 1450 is incident on the internal coupling grating 1452, where it passes through red color filter R2 and the other waveguide layers until it is diffracted into the plane of the waveguide layer 1450. Light intended for the blue waveguide layer 1460 is incident on the internal coupling grating 1462, where it passes through blue color filter B1 and the other waveguide layers until it is diffracted into the plane of the waveguide layer 1460. Light intended for the green waveguide layer 1470 is incident on the internal coupling grating 1472, where it passes through green color filter G2 and the other waveguide layers until it is diffracted into the plane of the waveguide layer 1470.

[0124] In some embodiments, a single color filter may be disposed across two internal coupling gratings, e.g., replacing R1 and R2 and a single color filter overlapping more than one internal coupling grating. Thus, while a circular color filter is illustrated in Figures 14A and 14C, other geometric shapes may be utilized in other embodiments. In some embodiments, the color filter may be the same shape as the concentrator used to collect light from the light source (e.g., light source 205). For example, the color filter may be octagonal to match the shape of the compound parabolic concentrator used to collect light from the light source.

[0125] To control the depth and color of the image transmitted through the waveguide during any one field period as the image is projected into the upper pupil, it is desirable to have light enter only one internal coupling grating at a time. Although the optical system may have high diffraction efficiency, higher diffraction orders may still be present within the projected pupil of the optical system. These higher order images may couple into the internal coupling grating unintendedly and create artifacts.

[0126] FIG. 15 illustrates a top view of diffraction orders within a distributed sub-pupil architecture, according to one embodiment. Upper pupil 1505 includes six sub-pupils: B1, B2, G1, G2, R1, and R2. Zero-order light passes through the red internal coupling grating and is incident on sub-pupil R2 for imaging, since sub-pupil R2 overlaps with the red internal coupling grating. Higher diffraction orders are also illustrated, with the first diffraction order surrounding the zeroth order and the second diffraction order surrounding the first diffraction order. For example, as illustrated in FIG. 15, the third diffraction order 1510 can overlap with sub-pupil B1. If light at these higher orders were coupled into the eyepiece by the blue internal coupling grating, shifted, upright artifacts would be present in the image extracted from the waveguide.

[0127] Thus, embodiments of the present disclosure match color filters so that higher diffraction orders have little or no overlap with filters of the same color or spectrally adjacent colors. In particular, embodiments position color filters taking into account the location of the first and / or second diffraction orders. Thus, the arrangement of the color filters is selected as a function of wavelength, the location of the diffraction orders, the location of the internal coupling grating, and the location of the optical axis of the lens.

[0128] FIG. 16A is a side view of an eyepiece with an optical filter, according to some embodiments. The eyepiece 1600 illustrated in FIG. 16A is an element of the VOA illustrated in FIG. 1 and can be used to project an image into a viewer's eye (e.g., viewer's eye 102). The eyepiece 1600 includes a first planar waveguide 1610 positioned in a first lateral plane. In this example, the first lateral plane extends within the plane of FIG. 16A and can be considered the xy plane. Light incident on the eyepiece 1600 along the z-direction will impinge normal to the lateral plane. As described herein, various optical elements are positioned at predetermined locations within the lateral plane to achieve the performance provided by the methods and systems described herein.

[0129] The first planar waveguide 1610 includes a first diffractive optical element (DOE) 1618 positioned at a first lateral position (i.e., x-y coordinate position). The first planar waveguide 1610 has a first surface 1614 and a second surface 1616 opposite the first surface 1614. Light is incident on the first planar waveguide 1610 in a first region 1605 to the left of the splitter 1601. The first region 1605 includes a first lateral position and a diffractive optical element associated with each of the planar waveguides. The first region 1605 is configured to receive an eyepiece, for example, image light incident on the first surface 1614 of the first planar waveguide 1610. The image light includes one or more wavelengths, for example, image light within three wavelength ranges associated with red (600 nm to 700 nm), green (500 nm to 600 nm), and blue (400 nm to 500 nm). The present disclosure is not limited to these wavelength ranges or three colors, or other ranges and more than three colors (e.g., RBGY) or less than three colors. Thus, these wavelength ranges are merely exemplary and can be modified as needed for a particular application.

[0130] The first planar waveguide 1610 also includes a second region 1607 to the right of the splitter 1601. Light incident on the first region 1605 is diffracted into the plane of the first planar waveguide 1610 and directed toward the second region 1607 of the first planar waveguide 1610. Thus, a portion of the image light is transmitted through the first planar waveguide 1610. Referring to FIG. 16A , a green incident beam 1642 is incident on the first DOE 1618. A portion of the green incident beam 1642 is diffracted and directed into the second region 1607 of the first planar waveguide 1610, as illustrated by guided ray 1619.

[0131] The second planar waveguide 1620 is positioned in a second lateral plane adjacent to the first lateral plane. In the example illustrated in Figure 16A, the second lateral plane is at a location in the xy plane that has a smaller z-dimension value than the first lateral plane. The second planar waveguide 1620 includes a second DOE 1628 disposed at a second lateral position (i.e., xy coordinate position).

[0132] The description provided with respect to the first planar waveguide 1610 can be applied to the second planar waveguide 1620, if desired. For example, the second planar waveguide 1620 has a first surface 1624 and a second surface 1626 opposite the first surface 1624. The second planar waveguide 1620 has a first region 1605 and a second region 1607, which include a second lateral position. Similar to the first planar waveguide 1610, the first region 1605 is configured to receive image light. The image light impinging on the second planar waveguide 1620, illustrated by incident beam 1644, includes light within a second wavelength range (e.g., blue light). The second planar waveguide 1620 also includes a second DOE 1628 configured to diffract image light within a second wavelength range into the second planar waveguide 1620 so that the image light is guided toward a second region 1607 of the second planar waveguide 1620. The light guided within the second region 1607 is represented by guided rays 1629.

[0133] The third planar waveguide 1630 is positioned in a third lateral plane adjacent to the second lateral plane. In the example illustrated in FIG. 16A , the third lateral plane is at a location in the xy plane with a smaller z-dimension value than the second lateral plane. The third planar waveguide 1630 includes a third DOE 1638 disposed at a third lateral position (i.e., an xy coordinate position) that can be different from both the first lateral position and the second lateral position. In the embodiment illustrated in FIG. 16A , the first lateral position is different from the second lateral position and the third lateral position, and the second lateral position is different from the first lateral position and the third lateral position, providing independent access to each of the DOEs for the incident beams 1642, 1644, 1646, and 1648. The descriptions provided with respect to the first planar waveguide 1610 and the second planar waveguide 1610 are applicable to the third planar waveguide 1630, as appropriate.

[0134] 16A , the third planar waveguide 1630 has a first surface 1634 and a second surface 1636 opposite the first surface 1634. The third planar waveguide 1630 has a first region 1605 and a second region 1607 including a third lateral position. The first region 1605 is configured to receive image light within a third wavelength range (e.g., a red wavelength range). A third DOE 1638 associated with the third planar waveguide 1630 is configured to diffract image light within the third wavelength range (e.g., red light) represented by an incident beam 1648 into the third planar waveguide 1630 so that the image light is guided toward the second region 1607 of the third planar waveguide 1630. The light guided within the second region 1607 is represented by guided light rays 1639.

[0135] 16A, an optical filter 1650 (e.g., a dichroic filter or an absorptive filter) is positioned between the second planar waveguide 1620 and the third planar waveguide 1630. The optical filter 1650 is disposed at a third lateral position so as to be aligned with the third DOE 1638.

[0136] As described herein, the optical filter 1650 improves system performance by reducing wavelength cross-coupling. Wavelength cross-coupling can occur when incident light is reflected by a DOE (e.g., an internal coupling grating). Referring to FIG. 1 , the projector 101 projects image light from an LCOS onto the internal coupling grating 107 in the eyepiece layer of the eyepiece 100. A portion of the image light can be reflected by the internal coupling grating 107. The reflected light can illuminate the LCOS. In some cases, pixels in the LCOS can act like mirrors and reflect light back to the internal coupling grating 107 without a change in polarization state. The reflected light can cause afterimages. The absorptive optical filter 1650 can filter (e.g., reflect) undesired light and eliminate or reduce afterimages. For example, if the optical filter 1650 is a dichroic filter, it can reflect blue light. In this case, a blue DOE and a red DOE can be arranged in series. In this arrangement, the blue light can be recycled, as further described in connection with Figure 18A. Placing DOEs (e.g., internal coupling gratings) in series can allow for more pupil or depth within a specific upper pupil size. In some cases, DOE diffraction can produce an afterimage image, which can be absorbed by a color filter.

[0137] 16A , the third DOE 1638 is designed to diffract light within a third wavelength range (e.g., red light) into the third planar waveguide 1630. In practice, the third DOE 1638 may also diffract (i.e., cross-couple) some (e.g., small) amount of light of other colors (e.g., blue or green light) into the third planar waveguide 1630. Such cross-coupling may adversely affect the user experience if this cross-coupled light is subsequently directed toward a user along with the desired light in the third wavelength range.

[0138] 16A , the light incident on the third DOE 1638 includes not only incident beam 1648, which is within the third wavelength range and intended to be coupled into the third planar waveguide 1630, but also incident beam 1646, which is not within the third wavelength range. This example illustrates how light within a first wavelength range and / or a second wavelength range can be incident on the third DOE 1638. To block light from the first wavelength range and / or the second wavelength range from being cross-coupled into the third planar waveguide 1630, embodiments of the present disclosure utilize an optical filter 1650 to reflect or absorb light at undesired wavelengths.

[0139] 16B is a plot illustrating the transmittance / reflectance curve of an optical filter according to some embodiments. The dichroic properties illustrated in FIG. 16B can be applied to one or more of the optical filters described herein. In the embodiment illustrated in FIG. 16A, the optical filter is a long-pass filter operable to transmit light within a third wavelength range (e.g., red wavelengths, such as 600 nm to 700 nm) and reflect light within a second wavelength range (e.g., blue wavelengths, such as 400 nm to 500 nm). The optical filter can also reflect wavelengths within a first wavelength range (e.g., green wavelengths, such as 500 nm to 600 nm).

[0140] The eyepiece design illustrated in FIG. 16A provides lateral spatial separation between the green and red input beams, allowing the filter design to be optimized for red and blue wavelengths at opposite ends of the visible spectrum. Therefore, spatial separation can be used in conjunction with one or more optical filters to reduce or prevent cross-coupling. The transmittance in the wavelength range associated with the third DOE and the third planar waveguide can be about 90% or greater, e.g., 95% or higher, up to 100%. The reflectance in the first wavelength range associated with the second DOE and the second planar waveguide can be about 10% or less, e.g., 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less.

[0141] A reflective optical filter may be utilized in some embodiments, while other embodiments may utilize an absorptive optical filter to provide wavelength selectivity. As an example, optical filter 1650 may be a long-pass filter operable to transmit light within a third wavelength range and absorb light at wavelengths below the third wavelength range.

[0142] 16A , the optical filter 1650 is disposed on the first surface 1634 of the third planar waveguide 1630, and the third DOE 1638 is disposed on the second surface 1636 of the third planar waveguide 1630. However, this arrangement is not required by the present disclosure, and other arrangements can be utilized, including placing the optical filter 1650 on the first surface 1614 or the second surface 1616 of the first planar waveguide 1610 or the first surface 1624 or the second surface 1626 of the second planar waveguide 1620. The first DOE 1618 is positioned on the second surface 1616 of the first planar waveguide 1610, the second DOE 1628 is positioned on the second surface 1626 of the second planar waveguide 1620, and the third DOE 1638 is positioned on the second surface 1636 of the third planar waveguide 1630, although this is not required and the DOEs can be positioned at different positions along the z-axis relative to the individual waveguides.

[0143] 17A is a side view of an eyepiece with absorbing color filters, according to some embodiments. An eyepiece 1700 is shown for projecting an image into a viewer's eye. The eyepiece includes a substrate 1710 positioned in a substrate-side plane. A set of color filters (e.g., absorbing color filters) including a first color filter 1712, a second color filter 1714, and a third color filter 1716 are disposed on the substrate 1710. The first color filter 1712 is disposed at a first lateral position operable to pass a first wavelength range (e.g., blue light, i.e., 400 nm to 500 nm), the second color filter 1714 is disposed at a second lateral position operable to pass a second wavelength range (e.g., red light, i.e., 600 nm to 700 nm), and the third color filter 1716 is disposed at a third lateral position operable to pass a third wavelength range (e.g., green light, i.e., 500 nm to 600 nm).

[0144] The eyepiece 1700 also includes a first planar waveguide 1720 positioned in a first lateral plane adjacent to the substrate lateral plane. The first planar waveguide 1720 includes a first diffractive optical element (DOE) 1713 disposed at a first lateral position below the first color filter 1712. The eyepiece 1700 also includes a second planar waveguide 1730 positioned in a second lateral plane adjacent to the first lateral plane, and a third planar waveguide 1740 positioned in a third lateral plane adjacent to the second lateral plane. The second planar waveguide 1730 includes a second DOE 1715 positioned at a second lateral position below the second color filter 1714, and the third planar waveguide 1740 includes a third DOE 1717 positioned at a third lateral position below the third color filter 1716.

[0145] In some embodiments, the color filters are fabricated using photoresist, which can be formed on the substrate 1710 using, for example, photolithography processes similar to those used in the fabrication of liquid crystal displays. The color filter thickness can be on the order of a few microns. As an example, the first color filter 1712 can be formed using a first photoresist operable to transmit a first wavelength range and attenuate a second wavelength range and a third wavelength range, the second color filter 1714 can be formed using a second photoresist operable to transmit a second wavelength range and attenuate the first wavelength range and the third wavelength range, and the third color filter 1716 can be formed using a third photoresist operable to transmit a third wavelength range and attenuate the first wavelength range and the second wavelength range.

[0146] The color filters can be positioned on both sides of the substrate 1710. In one embodiment, the substrate 1710 has a first side 1705 and a second side 1707, with the second side 1707 of the substrate 1710 facing the first planar waveguide. The set of color filters can be disposed on the first side 1705 of the substrate 1710, as illustrated in FIG. 17A. In some embodiments, the set of color filters is disposed on the second side 1707 of the substrate 1710 facing the first planar waveguide 1720.

[0147] In addition to photoresists, other suitable color filters using absorptivity can also be used, including ultraviolet inks. The inks can fill gaps and reduce Fresnel reflections due to index matching. In addition to absorptive color filters, reflective color filters, for example, based on multilayer coatings, can also be used in the embodiments described herein.

[0148] FIG. 17B is a plan view of the eyepiece 1700 shown in FIG. 17A. As shown in the plan view of FIG. 17B, different color filters can be positioned opposite each other across the optical axis, for example. In FIG. 17B, red and green absorbing color filters can be mirrored on opposite sides of the optical system, positioned opposite each other so that light reflected through the system will be absorbed. As an example, light reflected from a green DOE will be incident on a red color filter, absorbed, and not coupled into the red DOE. In this embodiment, the color filter is positioned above a DOE associated with a particular color passed by the color filter. Thus, as shown in FIG. 17B, an embodiment of the present disclosure correlates the lateral position of the color filter with the lateral position of the DOE so that light intended for the waveguide layer passes through the color filter and is coupled into the waveguide. Light in other wavelength ranges that would otherwise (partially) couple into the DOE is absorbed. When light within the desired wavelength range is reflected from the DOE, after passing through the optical system and returning to the eyepiece 1700, it will be absorbed when it strikes an opposing color filter that absorbs the desired wavelength range. In some embodiments, filters of the same color, for example, two blue color filters, can face each other. This arrangement can help reduce afterimages. Internal coupling grating reflections pass through the blue filters twice, which will slightly degrade the reflection intensity (i.e., afterimage intensity).

[0149] Embodiments of the present disclosure provide an eyepiece with multiple depth planes. In these embodiments, the eyepiece 1700 also includes a fourth color filter disposed on the substrate at a fourth lateral position and operable to pass a second wavelength range, and a fifth color filter disposed at a fifth lateral position and operable to pass a third wavelength range. In a plan view, the second color filter can be positioned opposite the fourth color filter. The eyepiece also includes a fourth planar waveguide positioned in a fourth lateral plane adjacent to the third lateral plane, a fifth planar waveguide positioned in a fifth lateral plane adjacent to the fourth lateral plane, and a sixth planar waveguide positioned in a sixth lateral plane adjacent to the fifth lateral plane. The fourth planar waveguide includes a fourth DOE disposed at a fourth lateral position, the fifth planar waveguide includes a fifth DOE disposed at a fifth lateral position, and the sixth planar waveguide includes a sixth DOE disposed at a sixth lateral position. Optionally, the eyepiece can include a sixth color filter disposed at a sixth lateral position and operable to pass the first wavelength range. Due to the low level of coupling of red light into the blue DOE, this sixth color filter can be optional. If a sixth color filter is used, the fifth color filter can be positioned opposite the sixth color filter in plan view.

[0150] FIG. 17C is a side view of an eyepiece with absorbing color filters, according to some embodiments. In this embodiment, color filters 1712, 1714, and 1716 are formed on one of the planar waveguide layers (e.g., first planar waveguide 1720) rather than on the substrate 1710, which may be implemented using a cover glass. Variations are also within the scope of this disclosure, including positioning one or more color filters on the substrate and one or more color filters on one or more of the planar waveguides. In embodiments in which color filters are positioned between planar waveguides, maintaining the total internal reflection nature of the waveguide is desirable. Additionally, multiple substrates (i.e., cover glass layers) can be used in conjunction with color filters positioned between substrates. Such an arrangement can facilitate index matching and reduce Fresnel reflections. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0151] Figure 18A is a side view of an eyepiece with an aligned diffractive optical element and optical filter, according to some embodiments. Figure 18B is a perspective view of the elements of the eyepiece illustrated in Figure 18A. In Figures 18A and 18B, the eyepiece is illustrated as utilizing aligned DOEs. The eyepiece illustrated in Figures 18A and 18B shares some similarities with the eyepiece illustrated in Figure 16A, and the description provided in connection with Figure 16A is applicable to Figures 18A and 18B, as appropriate.

[0152] An eyepiece 1800, which can be used to project an image into a viewer's eye, includes a first planar waveguide 1810 positioned in a first lateral plane (i.e., a first longitudinal position). The first planar waveguide 1810 includes a first diffractive optical element (DOE) 1812 disposed at a first lateral position (i.e., a first x-y coordinate position). A first optical filter 1814 is coupled to the first planar waveguide 1810 at a second lateral position (i.e., a second x-y coordinate position) different from the first lateral position. The first DOE 1812 is associated with a first wavelength range, and the first optical filter 1814 can be implemented as an absorptive filter operable to absorb wavelengths outside the first wavelength range. As a result, if the first DOE 1812 is operable to diffract green light into the first planar waveguide 1810 but also couple some of the incident blue and red light into the first planar waveguide 1810, the first optical filter 1814 can absorb the diffracted blue and red light and improve the color performance of the first planar waveguide 1810. Depending on the color configuration of the waveguide layers, the first optical filter 1814 can be a short-pass filter if the first planar waveguide 1810 is designed to propagate blue light, or a long-pass filter if the first planar waveguide 1810 is designed to propagate red light. In the illustrated embodiment with green / blue / red waveguides, the first color filter is a notch filter.

[0153] A first optical filter 1814 can be disposed inside the second region 1807 of the first planar waveguide 1810 to absorb light propagating in the first planar waveguide 1810 from the first region 1805. Additionally, the first optical filter 1814 can be disposed within a cavity inside the first planar waveguide 1810, or disposed on a first surface (e.g., a top surface) or a second surface (e.g., a bottom surface) of the first planar waveguide 1810.

[0154] The eyepiece 1800 also includes a second planar waveguide 1820 positioned in a second lateral plane adjacent to the first lateral plane (i.e., a second longitudinal position). The second planar waveguide 1820 includes a second DOE 1822 positioned at a first lateral position below the first DOE 1812. The eyepiece 1800 also includes a third planar waveguide 1830 positioned in a third lateral plane adjacent to the second lateral plane (i.e., a third longitudinal position). The third planar waveguide 1830 includes a third DOE 1832 positioned at a first lateral position below the first DOE 1812 and the second DOE 1822 and aligned along the longitudinal direction (i.e., aligned with the z-axis). In some embodiments, the third DOE 1832 may be a reflective grating with a mirror coating for higher diffraction efficiency, and the first DOE 1812 and the second DOE 1822 may be transmissive type gratings.

[0155] The second optical filter 1840 is positioned between the second planar waveguide 1820 and the third planar waveguide 1830. The second optical filter 1840 is disposed at a first lateral position.

[0156] Although all three DOEs (e.g., first DOE 1812, second DOE 1822, and third DOE 1832) are aligned in the embodiment illustrated in FIG. 18A , this is not required by the present disclosure, and the DOEs can be spatially separated at different lateral positions. As an example, the first DOE 1812 (e.g., for diffracting green light) can be aligned or spatially separated from the second DOE 1822 and third DOE 1832. In this example, green light is spatially separated from blue and red light because it is in the center of the visible spectrum, which is not significantly diffracted within the DOEs for the other colors, allowing the blue and red DOEs (e.g., second DOE 1822 and third DOE 1832) to be spatially aligned. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0157]

[00130] Embodiments of the present disclosure may utilize one or more dichroic reflectors to recycle light, resulting in a brighter image. Referring to Figure 18A, the third input beam 1802 (e.g., a red input beam) is not significantly coupled into the second DOE 1822 (e.g., a DOE configured to diffract blue light). Thus, the third input beam 1802 passes through the second DOE 1822 with little loss due to diffraction. The image light in the second input beam 1804 (e.g., a blue input beam) that is not diffracted by the second DOE 1822 is reflected from the second optical filter 1840 and impinges on the second DOE 1822 a second time, this time from the opposite direction to the first impingement by the blue light on the second DOE 1822. The second DOE 1822 diffracts the image light within the second wavelength range reflected by the second optical filter 1840 into the second planar waveguide 1820 so that it is guided toward the second region 1807 of the second planar waveguide 1820, thereby improving brightness for the user.

[0158] 19 is a side view of an eyepiece with an optical filter integrated into the eyepiece's waveguide, according to some embodiments. In the embodiment illustrated in FIG. 19, a color filter having a profile thicker than the separation distance between the substrate and the waveguide, which is typically about 30 μm, can be utilized to provide color selectivity.

[0159] Referring to FIG. 19 , an eyepiece 1900 can be used to project an image onto a viewer's eye and includes a cover glass 1910 and a substrate 1920 positioned in a substrate lateral plane. The substrate 1920 includes a first color filter 1922 (e.g., a long-pass filter operable to pass red light) disposed at a first lateral position and operable to pass a first wavelength range. The first color filter, in this embodiment, is operable to transmit the first wavelength range and attenuate the second and third wavelength ranges. The substrate 1920 also includes a second color filter 1924 (e.g., a notch filter operable to pass green light) disposed at a second lateral position and operable to pass the second wavelength range. The second lateral position is different from the first lateral position. The second color filter 1924 is operable to transmit the second wavelength range and to attenuate the first wavelength range and the third wavelength range.

[0160] The substrate 1920 can include a first recess in which a first color filter 1922 is disposed and a second recess in which a second color filter 1924 is disposed.

[0161] The eyepiece lens 1900 also includes a first planar waveguide 1930 positioned in a first lateral plane adjacent to the substrate lateral plane. The first planar waveguide 1930 includes a first diffractive optical element (DOE) 1932 disposed at a first lateral position below the first color filter 1922. The first DOE 1932 is operable to diffract light within a first wavelength range into the first planar waveguide 1930. The first planar waveguide 1930 also includes a third color filter 1934 (e.g., a short-pass filter operable to pass blue light) disposed at a third lateral position and operable to pass a third wavelength range. The third lateral position is different from the first and second lateral positions. The first planar waveguide 1930 may include a recess in which the third color filter 1934 is disposed. The third color filter 1934 is operable to transmit a third wavelength range and to attenuate the first wavelength range and the second wavelength range.

[0162] The eyepiece 1900 also includes a second planar waveguide 1940 positioned in a second lateral plane adjacent to the first lateral plane, and a third planar waveguide 1950 positioned in a third lateral plane adjacent to the second lateral plane. The second planar waveguide 1940 includes a second DOE 1942 positioned in a third lateral position below the third color filter 1934, and the third planar waveguide 1950 includes a third DOE 1952 positioned in a second lateral position below the second color filter 1924. In the illustrated embodiment, the first planar waveguide 1930 couples and propagates red light (i.e., the first wavelength range includes 600 nm to 700 nm), the second planar waveguide 1940 couples and propagates blue light (i.e., the third wavelength range includes 400 nm to 500 nm), and the third planar waveguide 1950 couples and propagates green light (i.e., the second wavelength range includes 500 nm to 600 nm). In plan view, the second color filter 1924 can be positioned opposite the third color filter 1934.

[0163] In some embodiments, at least one of the first color filter 1922, the second color filter 1924, or the third color filter 1934 is cut from a color filter sheet or plate, which can be laminated onto the substrate 1920 or a planar waveguide (e.g., the first planar waveguide 1930, the second planar waveguide 1940, and / or the third planar waveguide 1950), lowered into a recess formed in the substrate 1920 or a planar waveguide, or the like. The color filters (e.g., the first color filter 1922, the second color filter 1924, and / or the third color filter 1934) can have a thickness of about several hundred microns, which can exceed the separation distance between the substrate 1920 and / or the planar waveguides (e.g., less than about 50 μm), so that a recess or opening can be formed in the substrate 1920 or the planar waveguide to accommodate the thicker color filter. The recesses can extend a percentage of the thickness of the substrate 1920 or planar waveguide, and the apertures can pass completely through the substrate 1920 or planar waveguide. By embedding color filters within the substrate 1920 and / or planar waveguide, or by positioning color filters in apertures that pass through the substrate 1920 and / or planar waveguide, the separation distance between the substrate 1920 and / or planar waveguide can be maintained at a desired value.

[0164] To provide the second depth plane, the eyepiece 1900 can include a fourth color filter disposed at a fourth lateral position and operable to pass a first wavelength range, and a fifth color filter disposed at a fifth lateral position and operable to pass a second wavelength range. In a plan view, the fourth color filter can be positioned opposite the fifth color filter. The eyepiece 1900 can also include a fourth planar waveguide positioned in a fourth lateral plane adjacent to the third lateral plane, a fifth planar waveguide positioned in a fifth lateral plane adjacent to the fourth lateral plane, and a sixth planar waveguide positioned in a sixth lateral plane adjacent to the fifth lateral plane. The fourth planar waveguide includes a fourth DOE disposed at a fourth lateral position, the fifth planar waveguide includes a fifth DOE disposed at a fifth lateral position, and the sixth planar waveguide includes a sixth DOE disposed at a sixth lateral position. In some implementations, a sixth color filter can be disposed at the sixth lateral position operable to pass a third wavelength range, for example, a blue filter that can block red light and is not significantly coupled into the blue DOE. The sixth color filter can be positioned opposite the first color filter.

[0165] FIG. 20 is a perspective view of an eyepiece with a molded waveguide, according to some embodiments. The eyepiece 2000 reduces the intensity of Fresnel reflections from the eyepiece surface, thereby reducing residual reflections that may occur within the optical system. The eyepiece 2000 can be used to project an image into a viewer's eye and includes one or more planar waveguides. A first planar waveguide 2010 is positioned in a first lateral plane. The first planar waveguide 2010 includes a first diffractive optical element (DOE) 2012 disposed at a first lateral position. The first planar waveguide 2010 has a first boundary 2014 that encompasses a first surface area measured in the lateral plane.

[0166] The second planar waveguide 2020 is positioned in a second lateral plane adjacent to the first lateral plane. The second planar waveguide 2020 includes a second DOE 2022 disposed at a second lateral position outside the first boundary. The second planar waveguide 2020 has a second boundary 2024 enclosing a second surface area measured in the lateral plane. Because the second DOE 2022 is positioned outside the first boundary 2014 associated with the first planar waveguide 2010, light incident on the second DOE 2022 does not interact with or reflect from the first planar waveguide 2010.

[0167] The third planar waveguide 2030 is positioned in a third lateral plane adjacent to the second lateral plane. The third planar waveguide 2030 includes a third DOE 2032 disposed at a third lateral position outside the first boundary 2014 and outside the second boundary 2024. Because the third DOE 2032 is positioned outside the first boundary 2014 associated with the first planar waveguide 2010 and the second boundary 2024 associated with the second planar waveguide 2020, light incident on the third DOE 2024 does not interact with or reflect from either the first planar waveguide 2010 or the second planar waveguide 2020.

[0168] The first DOE 2012 is disposed in a peripheral region of the first boundary 2014, which may include one or more peripheral cutouts on either side of the first DOE 2012. In some embodiments, the first boundary 2014 may include one or more central orifices through which light directed into the second planar waveguide 2020 and the third planar waveguide 2030 can pass. Thus, various methods are provided by embodiments of the present disclosure that allow light intended for each waveguide to reach the appropriate DOE without passing through portions of other waveguides by removing portions of other waveguides that would otherwise reflect the incident light intended for each waveguide. While FIG. 20 illustrates the DOEs positioned on a peninsula-like protrusion from the central area of ​​the eyepiece 2000, this is not required by the present disclosure, and other waveguide shapes are within the scope of the present disclosure.

[0169] 21 is a flowchart illustrating a method of operating an eyepiece including one or more planar waveguides, according to some embodiments. Method 2100 provides the ability to couple light into an eyepiece including one or more planar waveguides. Method 2100 includes directing a first beam including a first wavelength to impinge on the eyepiece (2110) and coupling at least a portion of the first beam into a first planar waveguide of the one or more planar waveguides (2112). Method 2100 also includes directing a second beam including a second wavelength to impinge on the eyepiece (2114) and coupling at least a portion of the second beam into a second planar waveguide of the one or more planar waveguides (2116). Method 2100 further includes directing a third beam comprising a third wavelength to impinge on the eyepiece (2118), passing a transmitted portion of the third beam through an optical filter (2120), and coupling at least a portion of the transmitted portion of the third beam into a third planar waveguide of the one or more planar waveguides (2122).

[0170] It should be understood that the specific steps illustrated in FIG. 21 provide a particular method of operating an eyepiece including one or more planar waveguides, according to some embodiments. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments may perform the steps outlined above in a different order. Furthermore, individual steps illustrated in FIG. 21 may include multiple sub-steps that may be performed in various sequences, depending on the needs of the individual step. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0171] FIG. 22 is a flowchart illustrating a method of operating an eyepiece, according to some embodiments. Method 2200 enables light to be coupled into an eyepiece including one or more planar waveguides having a diffractive optical element associated with each of the one or more planar waveguides. Method 2200 includes directing (2210) a first beam including a first wavelength, a second beam including a second wavelength, and a third beam including a third wavelength to impinge on the eyepiece at a first lateral location (e.g., an input port). Method 2200 also includes coupling (2212) at least a portion of the first beam, at least a portion of the second beam, and at least a portion of the third beam into a first planar waveguide of the one or more planar waveguides and attenuating (2214) at least a portion of the second beam and at least a portion of the third beam.

[0172] The method 2200 further includes coupling (2216) at least a second portion of the second beam into a second planar waveguide of the one or more planar waveguides, passing (2218) the transmitted portion of the third beam through an optical filter, and coupling (2220) at least a portion of the transmitted portion of the third beam into a third planar waveguide of the one or more planar waveguides.

[0173] According to some embodiments, a diffractive optical element associated with each of the one or more planar waveguides is aligned at a first lateral position. Method 2200 can include reflecting the reflected portion of the third beam from an optical filter. Method 2200 can additionally include coupling at least a portion of the reflected portion of the third beam into a second planar waveguide.

[0174] It should be understood that the specific steps illustrated in FIG. 22 provide a particular method of operating an eyepiece according to some embodiments. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments may perform the steps outlined above in a different order. Furthermore, individual steps illustrated in FIG. 22 may include multiple sub-steps that may be performed in various sequences, depending on the needs of the individual step. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0175] FIG. 23 is a schematic diagram illustrating a side view of an eyepiece, according to some embodiments. FIG. 23 is similar to FIG. 16A. As shown in FIG. 23, the eyepiece 2300 is an element of the VOA illustrated in FIG. 1 and can be used to project an image into a viewer's eye. The eyepiece 2300 includes a first planar waveguide layer 2310 positioned in a first lateral plane. In this example, the first lateral plane extends within the plane of FIG. 23 and can be considered the xy plane. Light incident on the eyepiece 2300 along the z-direction will impinge normal to the lateral plane. As described herein, various optical elements are positioned at predetermined locations within the lateral plane to achieve the performance provided by the methods and systems described herein.

[0176] The first planar waveguide layer 2310 includes a first diffractive optical element (DOE) 2318 disposed at a first lateral position (i.e., x-y coordinate position). The first planar waveguide layer 2310 has a first surface 2314 and a second surface 2316 opposite the first surface 2314. Light is incident on the first planar waveguide layer 2310 in a first region 2305 to the left of the splitter 2301. The first region 2305 includes a first lateral position and a diffractive optical element (DOE) associated with each of the planar waveguide layers. The first region 2305 is configured to receive image light incident on the eyepiece lens 2300, for example, the first surface 2314 of the first planar waveguide layer 2310. The image light includes one or more wavelengths, for example, image light within three wavelength ranges associated with red (600 nm to 700 nm), green (500 nm to 600 nm), and blue (400 nm to 500 nm). The present disclosure is not limited to these wavelength ranges or three colors, or other ranges and more than three colors (e.g., RBGY) or less than three colors. Thus, these wavelength ranges are merely exemplary and can be modified as needed for a particular application.

[0177] The first planar waveguide layer 2310 also includes a second region 2307 to the right of the splitter 2301. Light incident on the first region 2305 is diffracted into the plane of the first planar waveguide layer 2310 and directed towards the second region 2307 of the first planar waveguide layer 2310. Thus, a portion of the image light is transmitted through the first planar waveguide layer 2310. A green incident beam 2342 is incident on the first DOE 2318. A portion of the green incident beam 2342 is diffracted and directed into the second region 2307 of the first planar waveguide layer 2310, as illustrated by guided ray 2319.

[0178] The second planar waveguide layer 2320 is positioned in a second lateral plane adjacent to the first lateral plane. In the example illustrated in FIG. 23, the second lateral plane is at a location in the xy plane having a smaller z-dimension value than the first lateral plane. The second planar waveguide layer 2320 includes a second DOE 2328 disposed at a second lateral position (i.e., xy coordinate position). In the embodiment illustrated in FIG. 23, the second lateral position is different from the first lateral position and provides independent access to each of the DOEs for the incident beams 2342, 2344, and 2348.

[0179] The description provided with respect to the first planar waveguide layer 2310 is applicable to the second planar waveguide layer 2320, if desired. For example, the second planar waveguide layer 2320 has a first surface 2324 and a second surface 2326 opposite the first surface 2324. The second planar waveguide layer 2320 has a first region 2305 and a second region 2307, which include a second lateral position. Like the first planar waveguide layer 2310, the first region 2305 is configured to receive image light. The image light impinging on the second planar waveguide layer 2320, illustrated by incident beam 2344, includes light within a second wavelength range (e.g., blue light). The second planar waveguide layer 2320 also includes a second DOE 2328 configured to diffract image light within a second wavelength range into the second planar waveguide layer 2320 so that the image light is guided toward a second region 2307 of the second planar waveguide layer 2320. The light guided within the second region 2307 is represented by guided rays 2329.

[0180] The third planar waveguide layer 2330 is positioned in a third lateral plane (at a position in the z-dimension that is smaller than the second lateral plane). The third planar waveguide layer 2330 includes a third DOE 2338 disposed at a third lateral position that may be different from both the first lateral position and the second lateral position. The descriptions provided in connection with the first planar waveguide layer 2310 and the second planar waveguide layer 2320 are applicable to the third planar waveguide layer 2330, as appropriate.

[0181] 23 , the third planar waveguide layer 2330 has a first surface 2334 and a second surface 2336 opposite the first surface 2334. The third planar waveguide layer 2330 has a first region 2305 and a second region 2307 including a third lateral position. The first region 2305 is configured to receive image light within a third wavelength range (e.g., a red wavelength range). A third DOE 2338 associated with the third planar waveguide layer 2330 is configured to diffract image light within the third wavelength range, represented by incident beam 2348, into the third planar waveguide layer 2330 so that the image light is guided toward the second region 2307 of the third planar waveguide layer 2330. The light guided within the second region 2307 is represented by guided rays 2339.

[0182] Figure 24A is a schematic diagram illustrating an LCOS-based (liquid crystal on silicon-based) image projector according to some embodiments. Image projector 2400 includes a light source 2410, a first lens 2420, an LCOS (liquid crystal on silicon) device 2430, an optical element 2440, and a second lens 2450. Figure 24B is a schematic diagram illustrating an expanded view of the optical paths within LCOS-based image projector 2400 to unfold the optical paths. Figure 24A is similar to Figure 7A, and Figure 24B is similar to Figure 7B.

[0183] The image projector 2400 may include light in three primary colors: blue (B), green (G), and red (R). Such image light can be separated into constituent colors so that the image light in each constituent color can be coupled into a separate waveguide layer within the eyepiece. In some embodiments, the light source 2410 may include a group of red LEDs, a group of green LEDs, and a group of blue LEDs. For example, the light source 2410 may include one red LED, one green LED, and one blue LED according to the embodiment shown in FIGS. 24A and 24B. In other embodiments, the light source 2410 may include two red LEDs, two green LEDs, and two blue LEDs so that images are presented on two depth planes. Each LED may have an associated CPC (compound parabolic concentrator) or similar optical element to direct the LED light emission to a target. 24A and 24B, image projector 2400 includes red LED 2411, green LED 2412, and blue LED 2413, each including a separate CPC. The front surface of LED light source 2410 at plane 2401 is referred to herein as the CPC plane.

[0184] Image projector 2400 includes a first lens 2420, an LCOS device 2430, an optical element 2440, and a second lens 2450. Optical element 2440 may include a prism, mirror, and the like, configured to direct incident light to LCOS device 2430 and direct light reflected from LCOS device 2430 to an output of image projector 2400. LCOS device 2430 is configured to deliver color-sequential image light to pupil plane 2460 within pupil plane 2451. Pupil 2460 includes three sub-pupils: sub-pupil 2461 for an image in red, sub-pupil 2462 for an image in green, and sub-pupil 2463 for an image in blue. For example, in a frame of a color image, in a first time period, light 2415 from red LED 2411 is turned on and LCOS device 2430 selects a subset of pixels in the image frame to receive the red light. In a second time period, light 2415 from green LED 2412 is turned on and LCOS device 2430 selects another subset of pixels to receive the green light. Similarly, in a third time period, light 2415 from blue LED 2413 is turned on and LCOS device 2430 selects yet another subset of pixels to receive the blue light. The color image light is delivered to sub-pupils 2461, 2462, and 2463 in a color-sequential manner.

[0185] Image projector 2400 is configured to project image light into eyepiece 2490. Similar to eyepiece 2300 in FIG. 23, eyepiece 2490 includes three planar waveguide layers, each with a respective diffractive optical element (DOE) 2491, 2492, and 2493, which functions as an internal coupling grating (ICG) and can receive image light. Therefore, the terms "DOE" and "ICG" will be used interchangeably. As shown in FIG. 24B, red, green, and blue color image light delivered to subpupils 2461, 2462, and 2463, respectively, is received by DOEs in corresponding waveguide layers within eyepiece 2490. Eyepiece 2490 also includes an OPE 2495 and an EPE 2497 in each of the waveguide layers to deliver a color image to the user.

[0186] Similar to DOEs 2318, 2328, and 2338 in FIG. 23, the three sub-pupils 2461, 2462, and 2463 in FIG. 24B, which are located on separate waveguide layers and are spatially displaced, reduce interference of incident image light directed to each waveguide layer within eyepiece lens 2490.

[0187] 25A-25B are schematic diagrams illustrating an LED light source according to some embodiments. FIG. 25A is similar to FIG. 5A. FIG. 25A illustrates light illumination from a light source with six LED sources for six waveguide layers within the eyepiece for two depth planes. There are two red LEDs, two green LEDs, and two blue LEDs. The light illumination is shown on the CPC plane (e.g., plane 2401 in FIG. 24B) or in front of the LED light source (e.g., LEDs 2411, 2412, 2413). Alternatively, FIG. 25A can also represent light illumination at the output pupil (e.g., pupil plane 2460 in FIG. 24B). It can be seen that the light source illustrated in FIG. 25A utilizes approximately 36% of the available space. In other words, this light source arrangement has a fill factor of approximately 36%.

[0188] Figure 25B illustrates light illumination from another light source, with nine LED sources for three waveguide layers in the eyepiece for three depth planes. There are three red LEDs, three green LEDs, and three blue LEDs. Again, the light illumination is shown on the CPC plane (e.g., plane 2401 in Figure 24B) or in front of the LED light sources (e.g., LEDs 2411, 2412, 2413). This arrangement also exhibits limited light source fill factor.

[0189] Figures 26A-26C are schematic diagrams illustrating LED light sources, according to some embodiments. Figure 26A illustrates light illumination from a light source 2610 with three LED sources for two waveguide layers in the eyepiece for two depth planes. There is one red LED light source 2611, one green LED light source 2612, and one blue LED light source 2613. Each LED light source is rectangular, and the three LED light sources 2611, 2612, and 2613 are positioned adjacent to one another. The light illumination is shown on plane 2401 (e.g., the CPC plane) in Figure 24B or in front of the LED light sources 2611, 2612, and 2613. Alternatively, Figure 26A can also represent light illumination within the pupil plane 2460 in Figure 24B. It can be seen that the LED light sources 2611, 2612, and 2613 utilize substantially 100% of the available space. In other words, this LED light source array has a fill factor of approximately 100%. A higher fill factor can provide brighter image light within the display. In light source 2610, each LED light source can include one or more LED dies and a light concentrator, such as a CPC. In some embodiments, light source 2610 can include other types of light sources. In these embodiments, LED light sources 2611, 2612, and 2613 can be other types of light sources.

[0190] FIG. 26B illustrates light illumination from light source 2620 with six LED sources for two waveguide layers in the eyepiece for two depth planes. There are two red LED light sources 2621 and 2625, two green LED light sources 2622 and 2624, and two blue LED light sources 2623 and 2626. The light illumination is shown on plane 2401 in FIG. 24B or in front of the LED light sources. Alternatively, FIG. 26B can also represent light illumination in pupil plane 2460 in FIG. 24B. In FIG. 26B, the six LED light sources 2621, 2622, 2623, 2624, 2625, and 2626 are respectively arranged within six sectors of the circular-shaped light source 2620. Each LED light source has a wedge or pie shape. It can be seen that light sources 2621, 2622, 2623, 2624, 2625, 2626 utilize substantially 100% of the available space. In other words, this light source array has a fill factor of approximately 100%. A higher fill factor can provide brighter image light within the display. In light source 2620, each LED light source can include one or more LED dies and a light concentrator, such as a CPC.

[0191] FIG. 26C illustrates light illumination from light source 2630 with six LED sources for two waveguide layers within the eyepiece for two depth planes. There are two red LED light sources 2631 and 2633, two green LED light sources 2632 and 2635, and two blue LED light sources 2634 and 2636. The light illumination is shown on plane 2401 in FIG. 24B or in front of the LED light sources. Alternatively, FIG. 26C can also represent light illumination within pupil plane 2460 in FIG. 24B. In FIG. 26C, six rectangular LED light sources 2631, 2632, 2333, 2634, 2635, and 2636 are positioned within six regions of rectangular-shaped light source 2630, respectively. It can be seen that light sources 2631, 2632, 2333, 2634, 2635, and 2636 utilize substantially 100% of the available space. In other words, this light source array has a fill factor of about 100%. A higher fill factor can provide brighter image light within the display. In light source 2630, each LED light source can include one or more LED dies and a light concentrator, such as a CPC.

[0192] The geometries illustrated in Figures 26A-26C are not intended to limit the embodiments of the present disclosure, but merely provide examples of LED geometries that may be utilized according to some embodiments. In some embodiments, other geometries, including squares, triangles, hexagons, and the like, can also be utilized to provide sources suitable for use with one or more depth planes while increasing the fill factor. Other geometries of the RGB LED layout can also be arbitrary, which may require a corresponding ICG layout to match the geometry of the light source. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0193] 27A is a schematic diagram illustrating an image display system according to some embodiments. The image display system 2700 includes a white light source 2710 and an LCOS-based (liquid crystal on silicon-based) image projector 2701. The white light source 2710 may be a white LED light source 2710. The image projector 2701 includes a first lens 2720, an LCOS (liquid crystal on silicon) device 2730, an optical element 2740, and a second lens 2721. Similar to FIG. 24B, FIG. 27A is a schematic diagram illustrating an expanded view of the optical paths within the LCOS-based image projector to unfold the optical paths.

[0194] In some embodiments, the white light source 2710 can include one or more white LED light emitters. In some embodiments, each white LED light emitter can include a blue LED chip coated with a yellow phosphor layer to emit white light. In some embodiments, the white LED light emitter can have a combination of red, green, and blue to emit white light. The white light source 2710 can also have a concentrator, such as a CPC, to deliver the white light. In some embodiments, the white light source 2710 is configured in a square or rectangular shape, although other geometric shapes can be used depending on the application. The front surface of the white light source 2710, at plane 2711, is referred to herein as the CPC plane 2711.

[0195] Image display system 2700 includes a first lens 2720, an LCOS device 2730, an optical element 2740, and a second lens 2721. Optical element 2740 may include a prism, mirror, or the like, configured to direct incident light to LCOS device 2730 and direct light reflected from LCOS device 2730 to the output of image projector 2701. LCOS device 2730 is configured to deliver time-sequential image light to pupil 2750 on upper pupil plane 2751. Pupil 2750 sequentially contains grayscale image light for each of the three basic colors. For example, in a first time period, light 2715 from white light source 2710 is turned on, and LCOS device 2730 is configured to select a subset of pixels in the image frame for red light. In a second time period, light 2715 from white light source 2710 is turned on and LCOS device 2730 is configured to select another subset of pixels for green light. Similarly, in a third time period, light 2715 from white light source 2710 is turned on and LCOS device 2730 is configured to select yet another subset of pixels for blue light. Grayscale image light is delivered to pupil 2750, also referred to as the upper pupil, in a color-sequential manner.

[0196] In some embodiments, image display system 2700 may also include a shutter 2760 and a color filter (CF) 2770 for projecting color image light through sub-pupil 2780 to eyepiece 2790 in a color-sequential manner. In the embodiment of FIG. 27A , image display system 2700 is configured for a single depth plane. Similar to eyepiece 2300 in FIG. 23 , eyepiece 2790 in FIG. 27A includes three planar waveguide layers, each with a separate diffractive optical element (DOE), which can function as an internal coupling grating and receive image light. To simplify the drawing, only one waveguide layer is labeled in FIG. 27A with DOE 2791, orthogonal pupil expander (OPE) 2795, and exit pupil expander (EPE) 2797.

[0197] 27B-27D are schematic diagrams illustrating the operation of the shutter 2760 and color filter 2770 in the image display system 2700 in FIG. 27A. In some embodiments, the shutter 2760 may be a liquid crystal shutter. As shown in FIG. 27B, for a display system with a single depth plane, the shutter 2760 includes three regions: a first shutter region 2761, a second shutter region 2762, and a third shutter region 2763. Similarly, the color filter 2770 includes three regions: a first filter region 2771 for red, a second filter region 2772 for blue, and a third filter region 2773 for green. Each color filter region is aligned with a respective shutter region. Furthermore, the pupil or upper pupil 2780 includes three sub-pupils 2781, 2782, and 2783.

[0198] The shutter 2760 and color filter 2770 are configured to present each of the primary colors in a time-sequential manner. For example, as shown in FIG. 27B , during a first time period T1, white light 2715 from white light source 2710 is turned on, and LCOS device 2730 is configured to select a subset of pixels in an image frame for red light. A grayscale image from LCOS device 2730 is projected at pupil 2750. During time period T1, first shutter region 2761 is open, and second shutter region 2762 and third shutter region 2763 are closed, allowing the grayscale image light to reach first filter region 2771 of filter 2770. As a result, red image light is present in sub-pupil 2781, which is projected to the corresponding ICG or DOE in the waveguide layer for the red image.

[0199] 27C , in a second time period T2, white light 2715 from white light source 2710 is turned on, and LCOS device 2730 is configured to select a second subset of pixels for green light. A grayscale image from LCOS device 2730 is projected at pupil 2750. During time period T2, second shutter region 2762 is open, and first shutter region 2761 and third shutter region 2763 are closed, allowing the grayscale image light to reach second filter region 2772 of filter 2770. As a result, blue image light is present in sub-pupil 2782, which is projected to the corresponding ICG or DOE in the waveguide layer for the blue image.

[0200] Similarly, as shown in FIG. 27D , in a third time period T3, white light 2715 from white light source 2710 is turned on, and LCOS device 2730 is configured to select a third subset of pixels for blue light. Grayscale image light from LCOS device 2730 is delivered to pupil 2750. During time period T3, third shutter region 2763 is open, and first shutter region 2761 and second shutter region 2762 are closed, allowing the grayscale image light to reach third filter region 2773 of filter 2770. As a result, green light image light is present in sub-pupil 2783, which is projected to the corresponding ICG or DOE in the waveguide layer for the green image.

[0201] As described above, in image display system 2700, shutter 2760 and color filter 2770 are configured to operate in synchronization with LCOS device 2730 to present red, green, and blue color image light to sub-pupils 2781, 2782, and 2793, respectively. The color image light is received by ICGs or DOEs 2791 in corresponding waveguide layers in eyepiece 2790 to deliver a color image to a user. Sub-pupils 2781, 2782, and 2783 are spatially displaced and aligned with the respective ICGs or DOEs 2791 in eyepiece 2790. Furthermore, sub-pupils 2781, 2782, and 2783 are configured to fill sub-pupil 2780, with a fill factor of substantially 100%.

[0202] Figure 28 is a schematic diagram illustrating the operation of image light coupled into a waveguide layer in image display system 2700 of Figure 27, according to some embodiments. Figure 28 illustrates waveguide layer 2800 in a side view 2810 and a top view 2820. Waveguide layer 2800 can be one of the waveguide layers in eyepiece lens 2790 in image display system 2700 in Figure 27. The output pupil from the LCOS image projector is shown as 2830, which includes sub-pupils 2831, 2832, and 2832. After passing through a shutter and color filter, a sub-pupil is selected similar to sub-pupil 2780 in Figure 27A and is coupled into waveguide layer 2800 by a diffractive optical element (DOE) or input coupling grating (ICG) 2805. As shown in side view 2810, image light 2803 is in-coupled into waveguide layer 2800 and propagates in the x-direction 2809 of waveguide layer 2800 by total internal reflection (TIR).

[0203] As shown in top view 2820 of waveguide layer 2800, ICG 2805 is configured with a rectangular shape to match the shape of the image light provided to sub-pupils 2831, 2832, and 2833. It can be seen that ICG 2805 is elongated and extends perpendicular to the propagation direction 2809 of the image light within waveguide layer 2800. Thus, the elongated ICG 2805 can in-couple a greater amount of image light into waveguide layer 2800 for a brighter display. If ICG 2805 has a dimension that is elongated along the light propagation direction, some of the light that experiences TIR may impinge on ICG 2805 and diffract out of waveguide layer 2800, resulting in a loss of light intensity. As can be seen from FIG. 28 , ICG 2805 narrows in propagation direction 2809. Therefore, it does not diffract light that experiences TIR, which can result in a loss of light. Additionally, the elongated ICG 2805 may receive more light intensity.

[0204] FIG. 29A is a photographic image illustrating higher-order diffraction by an LCOS device in an image display system. In FIG. 29A, the image is taken at the upper pupil plane 2751 in FIG. 27A, and green light 2910, red light 2920, and blue light 2930 could represent LED light sources. Alternatively, they could also represent the placement of corresponding ICGs on individual waveguide layers of the eyepiece. FIG. 29A shows higher-order diffraction images 2911, 2912, and 2913 of green light 2910 by the LCOS device, and the like (not all labeled). It can be seen that the higher-order diffraction images are aligned horizontally and vertically from the light source. In the eyepiece, the higher-order diffraction images from green can impinge on the ICGs for red and blue, which can cause interference, also known as afterimages. FIG. 29A is similar to FIG. 15.

[0205] FIG. 29B is a schematic diagram illustrating a method for arranging internal coupling gratings (ICGs) in an image display system according to some embodiments. In the left portion of FIG. 29B, the ICGs for green, red, and blue are vertically aligned to match the RGB LED layout, which can cause interference because higher-order diffraction from the LCOS tends to be along the vertical or horizontal direction, as illustrated in FIG. 29A. Therefore, in some embodiments, the ICGs are arranged in a staggered or rotated manner, as shown in the right portion of FIG. 29B, to avoid interference caused by the higher-order diffraction of the LCOS. Thus, embodiments of the present disclosure utilize liquid crystal shutters and spatial rotation of the ICGs at a predetermined angle to reduce the level of ghosting resulting from diffraction by the LCOS.

[0206] 29C is a schematic diagram illustrating another method for arranging internal coupling gratings (ICGs) in an image display system according to some embodiments. In the left part of FIG. 29C, six ICGs for green, red, and blue are arranged in a symmetrical arrangement in which the green ICG and the blue ICG are vertically aligned, which may cause interference, as illustrated in FIG. 29A. Therefore, in some embodiments, the ICG patterns are tilted, for example, by 15°, as shown in the right part of FIG. 29B, to avoid interference and / or crosstalk caused by higher-order diffraction of the LCOS.

[0207] Figure 30 is a schematic diagram illustrating another image display system, according to some embodiments. Image display system 3000 is similar to image display system 2700 in Figure 27A, and the discussion provided in connection with Figure 27A is applicable to Figure 30, where appropriate. As described above in connection with Figures 27A-27D, image display system 2700 is configured to provide three color images to three waveguide layers of the eyepiece for a single depth plane. In contrast, image display system 3000 is configured to provide six color images to six waveguide layers of the eyepiece for two depth planes.

[0208] As shown in Figure 30, image display system 3000, according to some embodiments, includes a white light source 3010 and a liquid crystal on silicon-based (LCOS-based) image projector 3001. Image projector 3001 includes a first lens 3020, a liquid crystal on silicon (LCOS) device 3030, an optical element 3040, and a second lens 3021. Similar to Figure 27A, Figure 30 is a schematic diagram illustrating an expanded view of the optical paths within LCOS-based image projector 3001 to unfold the optical paths.

[0209] In image display system 3000, white light source 3010, first lens 3020, optical element 3040, and second lens 3021 are similar to the corresponding components in image display system 2700 in FIG. 27A . Optical element 3040 may include a prism, mirror, and the like, which is configured to direct incident light to LCOS device 3030 and direct light reflected from LCOS device 3030 to the output of image projector 3001. LCOS device 3030 is configured to deliver time-sequential image light to pupil 3050 on pupil plane 3051. Image projector 3001 is configured to sequentially project six grayscale or black-and-white images onto pupil 3050. Each image is configured to select pixels for each of the three primary colors. For example, in a first time period, light 3015 from the white LED light source 3010 is turned on and the LCOS device 3030 is configured to select a subset of pixels in the image frame for red light for a first depth plane. In a second time period, light 3015 from the white LED light source 3010 is turned on and the LCOS device 3030 is configured to select another subset of pixels for green light for the first depth plane. Similarly, in a third time period, light 3015 from the white LED light source 3010 is turned on and the LCOS device 3030 is configured to select yet another subset of pixels for blue light for the first depth plane. Similarly, in the fourth, fifth, and sixth time periods, the LCOS device 3030 is configured to select subsets of pixels for red, green, and blue light for a second depth plane, respectively. Thus, grayscale image light is delivered to the pupil 3050 in a color-sequential manner.

[0210] In some embodiments, image display system 3000 also includes a shutter 3060 and a color filter 3070 for projecting color image light through sub-pupil 3080 in a color-sequential manner for projection into an eyepiece (not shown). In the embodiment in Figure 30, image display system 3000 is configured for an eyepiece having two depth planes. Thus, the eyepiece includes six planar waveguide layers, each with a separate diffractive optical element (DOE), which functions as an internal coupling grating and can receive image light. In Figure 30, the eyepiece is not shown to simplify the drawing.

[0211] For a display system with two depth planes, the shutter 3060 includes six regions, each having a shutter for one of the colors. Similarly, the color filter 3070 includes six regions, each having a filter for one of the colors. Each filter region is aligned with a respective shutter region. Furthermore, the pupil 3050 and / or sub-pupil 3080 includes six sub-pupils.

[0212] As described above, in image display system 3000, shutter 3060 and color filter 3070 are configured to operate in synchronization with LCOS device 3030 to present red, green, and blue color image light, respectively, to one of the six sub-pupils. The color image light is received by an ICG or DOE in a corresponding waveguide layer in the eyepiece to deliver a color image to a user.

[0213] 31A-31C are schematic diagrams illustrating another image display system, according to some embodiments. As shown in FIG. 31A, image display system 3100 is similar to image display system 2700 in FIG. 27A. As described above in connection with FIGS. 27A-27D, image display system 2700 is configured using a single white light source 2710. In contrast, image display system 3100 is configured using multiple white light sources.

[0214] As shown in Figure 31A, image display system 3100, according to some embodiments, includes a white light source 3110 and a liquid crystal on silicon-based (LCOS-based) image projector 3101. Image projector 3101 includes a first lens 3120, a liquid crystal on silicon (LCOS) device 3130, an optical element 3140, and a second lens 3121. Similar to Figure 27A, Figure 31A is a schematic diagram illustrating an expanded view of the optical paths within an LCOS-based image projector to unfold the optical paths.

[0215] In image display system 3100, first lens 3120, optical element 3140, and second lens 3121 are similar to the corresponding components in image display system 2700 in FIG. 27. In one embodiment, white light source 3110 includes two LED white light sources 3111 and 3112. Optical element 3140 may include a prism, mirror, or the like, configured to direct incident light to LCOS device 3130 and direct light reflected from LCOS device 3130 to the output of image projector 3101. LCOS device 3130 is configured to deliver time-sequential image light to pupil 3150 on pupil plane 3151. Image projector 3101 is configured to sequentially project grayscale or black-and-white images onto pupil 3150. Each image is configured to select pixels for each of the three primary colors. In this embodiment, LED white light sources 3111 and 3112 are turned on sequentially.

[0216] In some embodiments, the image display system 3100 also includes a shutter 3160 and a color filter (CF) 3170 for projecting color image light through the sub-pupil 3180 to the eyepiece 3190 in a color-sequential manner. Depending on the embodiment, different combinations of shutters and color filters can be used within the image display system. For example, FIG. 31B illustrates a portion of an image projector having two white LED light sources 3111 and 3112, with a single shutter having three shutter regions. Furthermore, the color filter 3171 can have color regions for red, blue, and green that are matched for each LED light source. In contrast, in the color filter 3172, the red, blue, and green color filters can be staggered, which can result in little afterimages due to diffraction. 31C, the image projector has two white LED light sources 3111 and 3112 and two shutters 3162 and 3163, each with three shutter regions. Additionally, color filter 3173 can have color regions for red, blue, and green that are matched for each LED light source 3111, 3112. In contrast, in color filter 3174, the red, blue, and green color filters can be staggered.

[0217] As described above, the image display system 3100 can be configured to provide either three sub-pupils for a single depth plane or six sub-pupils for two depth planes for the eyepiece 3190. Thus, the eyepiece 3190 can include either three waveguide layers for a single depth plane or six waveguide layers for two depth planes. To simplify the drawing, only one waveguide layer is shown with a diffractive optical element (DOE) 3191, an OPE 3195, and an EPE 3197.

[0218] Figure 32 is a schematic diagram illustrating another image display system according to some embodiments. Image display system 3200 is similar to image display system 2700 in Figure 27A. As described above in connection with Figures 27A-27D, image display system 2700 is configured using a white light source and an image projector with a color-sequential LCOS device. In contrast, image display system 3200 is configured using a white light source and an image projector with a non-color-sequential LCOS device.

[0219] As shown in Figure 32, an image display system 3200, according to some embodiments, includes a white light source 3210 and a liquid crystal on silicon-based (LCOS-based) image projector 3201. The image projector 3201 includes a first lens 3220, a non-color sequential liquid crystal on silicon (LCOS) device 3230, an optical element 3240, and a second lens 3221. Similar to Figure 27A, Figure 32 is a schematic diagram illustrating an expanded view of the optical paths within an LCOS-based image projector to unfold the optical paths.

[0220] Certain components in image display system 3200 are similar to corresponding components in image display system 2700 in FIG. 27A , including a white light source 3210, a first lens 3220, an optical element 3240, and a second lens 3221. However, non-color sequential LCOS device 3230 is configured to receive white illumination light and project a full-color image onto pupil 3250 on pupil plane 3251. In some embodiments, non-color sequential LCOS device 3230 is configured with color filters to process images in three primary colors and provide a combined full-color image. In some embodiments, non-color sequential LCOS device 3230 may include three LCOS panels to process images in the three primary colors and provide a combined full-color image. In some embodiments, non-color sequential LCOS device 3230 may include a single integrated LCOS panel to process images in the three primary colors and provide a combined full-color image.

[0221] In some embodiments, the image display system 3200 also includes a shutter 3260 and a color filter (CF) 3270 for receiving a full-color image at the pupil 3250 and projecting color image light through the sub-pupil 3280 to the eyepiece 3290 in a color-sequential manner. In the embodiment of FIG. 32, the image display system 3200 is configured for a single depth plane. However, the system can also be applied to multiple depth planes. Similar to the eyepiece 2790 in FIG. 27A, the eyepiece 3290 in FIG. 32 includes three planar waveguide layers, each with a separate diffractive optical element (DOE), which can function as an internal coupling grating and receive image light. In FIG. 32, to simplify the drawing, only one waveguide layer is labeled with DOE 3291, OPE (orthogonal pupil expander) 3295, and EPE (exit pupil expander) 3297.

[0222] In some embodiments, the shutter 3260 can be a liquid crystal shutter. As shown in FIG. 32, for a display system with a single depth plane, the shutter 3270 includes three shutter regions. Similarly, the color filter 3270 includes three filter regions: a first filter region for red, a second filter region for blue, and a third filter region for green. Each filter region is aligned with a separate filter region. Furthermore, the pupil or upper pupil 3250 includes three sub-pupils, with only one sub-pupil 3280 shown in FIG. 32.

[0223] The shutters 3260 and color filters 3270 are configured to receive the full-color image at pupil 3250 and present each primary color image to eyepiece 3290 in a time-sequential manner. For example, in a first time period, the shutter area aligned with the red color filter area is opened, allowing the red image in the full-color image to pass through and form a sub-pupil of the red image, which is received at the DOE of the waveguide layer for red. In a second time period, the shutter area aligned with the green filter area is opened, allowing the green image in the full-color image to pass through and form a sub-pupil of the green image, which is received at the DOE of the waveguide layer for green. Similarly, in a third time period, the shutter area aligned with the blue filter area is opened, allowing the blue image in the full-color image to pass through and form a sub-pupil of the blue image, which is received at the DOE of the waveguide layer for blue. As described above, the ICG in each waveguide layer may be spatially displaced. Therefore, afterimage imaging from ICG reflection can be reduced.

[0224] As described above, in image display system 3200, shutter 3260 and color filter 3270 operate in synchronization with non-color sequential LCOS device 3230 and are configured to receive a full-color image from LCOS device 3230 and present red, green, and blue color image light, respectively. The color image light is received by ICG or DOE 3291 in a corresponding waveguide layer within eyepiece 3290 to deliver the color image to a user. Thus, each full-color image provided by LCOS device 3230 is projected into eyepiece 3290 in a color sequential manner, three single-color images in red, green, and blue, respectively. In this embodiment, the frame rate of LCOS device 3230, for example, 180 frames per second, can be fully utilized within eyepiece 3290. In contrast, in the image display system based on the color sequential LCOS device described above, the duration of three frames of the LCOS device is used to project a single frame into the eyepiece. As a result, only one-third of the frame rate of the LCOS device, eg, 60 frames per second, can be utilized in the projected image in the eyepiece.

[0225] While the above has been illustrated in terms of specific hardware features, it will be recognized that many variations, substitutions, and modifications may exist. For example, any of the hardware features may be further combined or further separated. Features may also be implemented in part through software or a combination of hardware and software. Hardware and software may also be further integrated, or less integrated, depending on the application. Further details of certain methods according to the present disclosure may be found more particularly throughout the specification below.

[0226] FIG. 33 is a flowchart illustrating a method for displaying an image, according to some embodiments. The method 3300 for displaying an image includes providing (3310) a white light source and an image projector. An example of a white light source is shown in FIG. 27A, where the white light source 2710 can include one or more white LED light emitters. Each white LED light emitter can include a blue LED chip coated with a yellow phosphor layer to emit white light. Alternatively, the white LED light emitter can have a combination of red, green, and blue to emit white light. The white light source 2710 can also have a concentrator, such as a CPC, to deliver the white light. In some embodiments, the white LED light source is configured in a square or rectangular shape. The front surface of the white LED light source at plane 2711 is referred to herein as the CPC plane.

[0227] In some embodiments, image projector 2701 is an LCOS-based image projector 2701. Image projector 2701 includes an LCOS device 2730 and various optical components for directing incident light to LCOS device 2730 and directing light reflected from LCOS device 2730 to an output of image projector 2701.

[0228] The method 3300 also includes receiving (3320) white light from a white light source at an image projector and sequentially projecting (3330) grayscale images at the optical pupil. The LCOS device 2730 is configured to deliver the time-sequential image light to a pupil 2750 on a pupil plane 2751. The pupil 2750 includes sequential grayscale image light for each of three basic colors. Each grayscale image is configured to select pixels for each of the three colors (e.g., primary colors).

[0229] The method 3300 also includes providing (3340) a shutter and color filters for dividing the optical pupil into three sub-pupils for the three primary colors. In some embodiments, the shutter 2760 can be a liquid crystal shutter. As shown in FIG. 27B , for a display system with a single depth plane, the shutter 2760 includes three regions: a first shutter region 2761, a second shutter region 2762, and a third shutter region 2763. Similarly, the color filter 2770 includes three regions: a first filter region 2771 for red, a second filter region 2772 for blue, and a third filter region 2773 for green. Each filter region is aligned with a separate filter region. The shutter and filter regions are aligned to divide pupil 2750 (eg, upper pupil) into three lower pupils 2781, 2782, and 2783 for the three primary colors, namely red, green, and blue.

[0230] The method 3300 further includes synchronizing the shutter and color filters with the grayscale image from the LCOS-based image projector to sequentially project images in each of the three primary colors at corresponding sub-pupils (3750). As shown in FIG. 27B , during a first time period T1, light 2715 from the white light source 2710 is turned on, and the LCOS device 2730 is configured to select a subset of pixels in the image frame for red light. The grayscale image from the LCOS device 2730 is projected at the pupil 2750. During the first time period T1, the shutter region 2761 is open, and the second shutter region 2762 and the third shutter region 2763 are closed, allowing the grayscale image light to reach the first filter region 2771 of the color filter 2770. As a result, red image light is present in the sub-pupil 2781.

[0231] 27C , in a second time period T2, light 2715 from white light source 2710 is turned on, and LCOS device 2730 is configured to select a second subset of pixels for green light. A grayscale image from LCOS device 2730 is projected at pupil 2750. During time period T2, second shutter region 2762 is open, and first shutter region 2761 and third shutter region 2763 are closed, allowing the grayscale image light to reach second filter region 2772 of color filter 2770. As a result, blue image light is present in lower pupil 2782.

[0232] 27D , in a third time period T3, light 2715 from white light source 2710 is turned on, and LCOS device 2730 is configured to select a third subset of pixels for blue light. Grayscale image light from LCOS device 2730 is delivered to pupil 2750. During time period T3, third shutter region 2763 is open, and first shutter region 2761 and second shutter region 2762 are closed, allowing the grayscale image light to reach third filter region 2773 of color filter 2770. As a result, green light image light is present in lower pupil 2783.

[0233] The method 3300 also includes providing (3360) an eyepiece having three waveguide layers. For example, as shown in FIG. 27A, eyepiece 2790 includes three planar waveguide layers, each with a respective diffractive optical element (DOE), which functions as an internal coupling grating and can receive image light. In FIG. 27A, to simplify the drawing, only one waveguide layer is labeled with DOE 2791, orthogonal pupil expander (OPE) 2795, and exit pupil expander (EPE) 2797. Each waveguide layer is configured to display an image in one of three colors (e.g., primary colors).

[0234] The method 3300 also includes sequentially receiving (3370) images in each of the three colors (e.g., primary colors) in a corresponding waveguide layer to project the images to a viewer. Referring back to Figures 27B-27D, during time T1, red image light is present in sub-pupil 2781, which is projected to a corresponding ICG or DOE in the waveguide layer for the red image. During time T2, blue image light is present in sub-pupil 2782, which is projected to a corresponding ICG or DOE in the waveguide layer for the blue image. During time T3, green image light is present in sub-pupil 2783, which is projected to a corresponding ICG or DOE in the waveguide layer for the green image. The eyepiece 2790 with three waveguide layers is configured to display color images to a viewer.

[0235] 34 is a flowchart illustrating another method for displaying an image, according to some embodiments. The method for displaying an image 3400 includes providing a white light source and an image projector (3410), receiving white light from the white light source at the image projector (3420), projecting an image at an optical pupil (3430), providing a shutter and color filters to divide the optical pupil into multiple sub-pupils (3440), synchronizing the shutter and color filters with the image from the image projector to sequentially project images in each of three primary colors at corresponding sub-pupils (3450), providing an eyepiece having multiple waveguide layers (3460), and sequentially receiving images in each of the three primary colors at corresponding waveguide layers to project a color image to a viewer (3470).

[0236] This method 3400 includes steps similar to method 3300 described above in connection with FIG. 33. However, method 3400 includes additional features. For example, as illustrated in FIGS. 27A-32, the white light source in step 3410 may include one or more white light sources, either separately controlled or integrated. Furthermore, the image projector in step 3410 may include a color-sequential LCOS-based image projector for projecting a grayscale or monochrome image onto the optical pupil. In some embodiments, the image projector can be a non-color-sequential LCOS-based image projector for projecting a full-color image onto the optical pupil. Furthermore, the optical pupil is not limited to three sub-pupils. Depending on the embodiment, the optical pupil can be divided into three sub-pupils for an eyepiece with a single depth plane, six sub-pupils for an eyepiece with two depth planes, nine sub-pixels for an eyepiece with three depth planes, or more sub-pixels for an eyepiece with more than three depth planes. Depending on the number of eyepieces and subpixels, the shutter can have a corresponding number of shutter regions and the color filter can have a corresponding number of filter regions. The shutters and color filters are configured to synchronize with either color sequential or non-color sequential LCOS-based projectors.

[0237] It should be understood that the specific steps illustrated in Figures 33 and 34 provide a particular method of operating an eyepiece according to some embodiments. Other sequences of steps may also be implemented in accordance with some embodiments. For example, some embodiments may implement the steps outlined above in a different order. Furthermore, individual steps illustrated in Figures 33 and 34 may include multiple sub-steps that may be implemented in various sequences, depending on the needs of the individual step. Furthermore, additional steps may be added or removed depending on the particular application. Those skilled in the art will recognize many variations, modifications, and alternatives.

[0238] According to one aspect of the present disclosure, an eyepiece lens unit including an optical filter is provided. The eyepiece lens unit includes a set of waveguide layers including a first waveguide layer and a second waveguide layer. The first waveguide layer is disposed in a first lateral plane and includes a first inward coupling diffractive element disposed at a first lateral position, a first waveguide optically coupled to the first inward coupling diffractive element, and a first outward coupling diffractive element optically coupled to the first waveguide. The second waveguide layer is disposed in a second lateral plane adjacent to the first lateral plane and includes a second inward coupling diffractive element disposed at a second lateral position, a second waveguide optically coupled to the second inward coupling diffractive element, and a second outward coupling diffractive element optically coupled to the second waveguide. The eyepiece also includes a set of optical filters including a first optical filter and a second optical filter. The first optical filter is positioned at a first lateral position and is operable to attenuate light outside a first spectral band, and the second optical filter is positioned at a second lateral position and is operable to attenuate light outside a second spectral band.

[0239] In one aspect, the set of waveguide layers includes a third waveguide layer, and the set of optical filters includes a third optical filter. The third waveguide layer is disposed in a third lateral plane and includes a third inward-coupling diffractive element disposed at a third lateral position, a third waveguide optically coupled to the third inward-coupling diffractive element, and a third outward-coupling diffractive element optically coupled to the third waveguide. The third optical filter is positioned at a third lateral position and is operable to attenuate light outside a third spectral band.

[0240] In one aspect, the first spectral band includes red wavelengths, the second spectral band includes green wavelengths, and the third spectral band includes blue wavelengths. The first optical filter can transmit at least one of the green wavelengths or the blue wavelengths, and the second optical filter can transmit at least one of the red wavelengths or the blue wavelengths. The set of optical filters can be disposed on a surface of a cover plate disposed in a third lateral plane adjacent to the first lateral plane.

[0241] The cover plate can include a low-transmittance medium between the sets of optical filters. The first optical filter can be disposed between the cover plate and the first waveguide layer. The cover plate can be disposed in a third lateral plane adjacent to the first lateral plane. The second optical filter can be disposed between the first waveguide layer and the second waveguide layer. The first lateral position and the second lateral position can be the same lateral position. The eyepiece unit can be disposed adjacent to the projection lens, and the set of optical filters can be disposed between the projection lens and the set of waveguide layers. The first lateral position can be laterally displaced relative to the second lateral position. The first internal coupling diffractive element can be configured to internally couple light within a first spectral band. The second internal coupling diffractive element can be configured to internally couple light within a second spectral band.

[0242] According to one aspect of the present disclosure, an artifact reduction system is provided. The artifact reduction system includes a projector assembly, a set of imaging optics optically coupled to the projector assembly, and an eyepiece optically coupled to the set of imaging optics. The eyepiece includes an internal coupling interface. The artifact reduction system also includes a set of optical filters including a first optical filter operable to attenuate light outside a first spectral band, a second optical filter operable to attenuate light outside a second spectral band, and a third optical filter operable to attenuate light outside a third spectral band.

[0243] In one aspect, the first spectral band includes red wavelengths, the second spectral band includes green wavelengths, and the third spectral band includes blue wavelengths. The internal coupling interface can include a plurality of internal coupling diffractive elements arrayed about the optical axis. The projector assembly can further include a polarizing beam splitter (PBS), a set of spatially displaced light sources positioned adjacent to the PBS, and a display panel positioned adjacent to the PBS. A set of imaging optics can be positioned adjacent to the PBS.

[0244] The projector assembly may further include a polarizing beam splitter (PBS), a set of spatially displaced light sources disposed adjacent to a first side of the PBS, a collimator disposed adjacent to a second side of the PBS, and a display panel disposed adjacent to a third side of the PBS. A set of imaging optics may be disposed adjacent to a fourth side of the PBS. The fourth side may be positioned between the first and second sides and opposite the third side. The display panel may include at least one of a reflective display or an LCOS display. The set of imaging optics may be configured to form an image at an internal coupling interface. The internal coupling interface may include at least one of a polarizing film, a wire grid polarizer, or a dielectric stack coating.

[0245] According to one aspect of the present disclosure, an eyepiece for projecting an image to a viewer's eye is provided. The eyepiece includes a first planar waveguide positioned in a first lateral plane. The first planar waveguide includes a first diffractive optical element (DOE) positioned at a first lateral position. The eyepiece also includes a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane. The second planar waveguide includes a second DOE positioned at a second lateral position different from the first lateral position. The eyepiece further includes a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane. The third planar waveguide includes a third DOE positioned at a third lateral position different from the first lateral position and the second lateral position. The eyepiece additionally includes an optical filter positioned between the second planar waveguide and the third planar waveguide, the optical filter being disposed at a third lateral position.

[0246] The optical filter can include a long-pass filter operable to transmit a first wavelength range and reflect a second wavelength range less than the first wavelength range. In one aspect, the first wavelength range includes 600 nm to 700 nm, and the second wavelength range includes 400 nm to 500 nm. The transmittance in the first wavelength range can be about 90% or greater. The reflectance in the second wavelength range can be about 10% or less. The optical filter can include a long-pass filter operable to transmit the first wavelength range and absorb the second wavelength range.

[0247] In one aspect, the first planar waveguide has a first surface and a second surface opposite the first surface, the first planar waveguide having a first region including a first lateral position and a second region, the first region configured to receive image light incident on the first surface, the image light including image light within a first wavelength range. The first DOE can be disposed in the first region and configured to diffract the image light within the first wavelength range into the first planar waveguide so that the image light is directed toward the second region of the first planar waveguide. A portion of the image light can be transmitted through the first planar waveguide.

[0248] The second planar waveguide can have a first surface and a second surface opposite the first surface. The second planar waveguide can have a first region including a second lateral position and a second region, the first region configured to receive image light within a second wavelength range. The second DOE can be disposed in the first region and configured to diffract image light within the second wavelength range into the second planar waveguide so that the image light is directed toward the second region of the second planar waveguide.

[0249] In one aspect, the third planar waveguide has a first surface and a second surface opposite the first surface. The third planar waveguide has a first region and a second region including a third lateral position, and the first region is configured to receive image light within a third wavelength range. A third DOE can be disposed within the first region and configured to diffract the image light within the third wavelength range into the third planar waveguide so that the image light is directed toward the second region of the third planar waveguide. An optical filter can be disposed on the first surface of the third planar waveguide. The third DOE can be disposed on the second surface of the third planar waveguide. The optical filter can be disposed on the first or second surface of the first planar waveguide or the first or second surface of the second planar waveguide.

[0250] According to one aspect of the present disclosure, an eyepiece for projecting an image to a viewer's eye is provided. The eyepiece includes a substrate positioned in a substrate lateral plane and a set of color filters disposed on the substrate. The set of color filters includes a first color filter disposed at a first lateral position and operable to pass a first wavelength range, a second color filter disposed at a second lateral position and operable to pass a second wavelength range, and a third color filter disposed at a third lateral position and operable to pass a third wavelength range. The eyepiece also includes a first planar waveguide positioned in a first lateral plane adjacent to the substrate lateral plane. The first planar waveguide includes a first diffractive optical element (DOE) disposed at the first lateral position. The eyepiece further includes a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane. The second planar waveguide includes a second DOE disposed at a second lateral position. The eyepiece additionally includes a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane. The third planar waveguide includes a third DOE disposed at a third lateral position.

[0251] The first color filter can include a first photoresist operable to transmit a first wavelength range and attenuate a second wavelength range and a third wavelength range. The second color filter can include a second photoresist operable to transmit a second wavelength range and attenuate the first wavelength range and a third wavelength range. The third color filter can include a third photoresist operable to transmit a third wavelength range and attenuate the first wavelength range and a third wavelength range. At least one of the first color filter, the second color filter, or the third color filter can include ultraviolet ink. In one aspect, the first color filter can be positioned opposite the third color filter about the optical axis in a plan view.

[0252] In one aspect, the substrate has a first side and a second side, and the set of color filters can be disposed on the first side of the substrate, with the second side of the substrate facing the first planar waveguide. In another aspect, the substrate has a first side and a second side, and the set of color filters can be disposed on the second side of the substrate, with the second side of the substrate facing the first planar waveguide.

[0253] The eyepiece may further include a fourth color filter disposed on the substrate at a fourth lateral position and operable to pass a second wavelength range, and a fifth color filter disposed at a fifth lateral position and operable to pass a third wavelength range. In plan view, the second color filter may be positioned opposite the fourth color filter about the optical axis. Additionally, the eyepiece may include a fourth planar waveguide positioned in a fourth lateral plane adjacent to the third lateral plane, a fifth planar waveguide positioned in a fifth lateral plane adjacent to the fourth lateral plane, and a sixth planar waveguide positioned in a sixth lateral plane adjacent to the fifth lateral plane. The fourth planar waveguide can include a fourth diffractive optical element (DOE) disposed at a fourth lateral position, the fifth planar waveguide can include a fifth DOE disposed at a fifth lateral position, and the sixth planar waveguide can include a sixth DOE disposed at a sixth lateral position.

[0254] The eyepiece can further include a sixth color filter disposed at a sixth lateral position and operable to pass the first wavelength range. In plan view, the fifth color filter can be positioned opposite the sixth color filter about the optical axis. In one aspect, the first wavelength range includes 400 nm to 500 nm (blue), the second wavelength range includes 600 nm to 700 nm (red), and the third wavelength range includes 500 nm to 600 nm (green).

[0255] According to one aspect of the present disclosure, an eyepiece for projecting an image to a viewer's eye is provided. The eyepiece includes a first planar waveguide positioned in a first lateral plane. The first planar waveguide includes a first diffractive optical element (DOE) positioned at a first lateral position. The eyepiece also includes a first optical filter coupled to the first planar waveguide at a second lateral position different from the first lateral position, and a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane. The second planar waveguide includes a second DOE positioned at the first lateral position. The eyepiece further includes a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane. The third planar waveguide includes a third DOE positioned at the first lateral position. Additionally, the eyepiece includes a second optical filter positioned between the second planar waveguide and the third planar waveguide, the second optical filter being disposed at the first lateral position.

[0256] In one aspect, the first DOE is configured to diffract light with a first wavelength range, and the first optical filter includes an absorptive filter operable to absorb wavelengths outside the first wavelength range. The first optical filter can include a filter configured to transmit light within the first wavelength range and absorb at least a portion of the light outside the first wavelength range. The first optical filter can be further configured to absorb at least a portion of light within a third wavelength range. The second optical filter can include a dichroic reflector. The second DOE can be configured to diffract light with a second wavelength range, and the second optical filter can be configured to reflect light with the second wavelength range toward the second DOE for diffraction into the second planar waveguide.

[0257] The first DOE can be disposed in a first region disposed at a first lateral position, and the first optical filter can be disposed in a second region of the first planar waveguide. The first optical filter can be disposed in a cavity inside the first planar waveguide. The first optical filter can be disposed on a first surface of the first planar waveguide. The first DOE can be configured to diffract light within a first wavelength range including 400 nm to 500 nm (green), the second DOE can be configured to diffract light within a second wavelength range including 400 nm to 500 nm (blue), and the third DOE can be configured to diffract light within a third wavelength range including 600 nm to 700 nm (red).

[0258] According to one aspect of the present disclosure, an eyepiece for projecting an image onto a viewer's eye is provided. The eyepiece includes a substrate positioned in a substrate lateral plane. The substrate includes a first color filter disposed at a first lateral position and operable to pass a first wavelength range, and a second color filter disposed at a second lateral position and operable to pass a second wavelength range. The substrate may further include a fourth color filter disposed at a fourth lateral position and operable to pass the first wavelength range, and a fifth color filter disposed at a fifth lateral position and operable to pass the second wavelength range. In a plan view, the fourth color filter may be positioned opposite the fifth color filter.

[0259] The eyepiece also includes a first planar waveguide positioned in a first lateral plane adjacent to the substrate lateral plane. The first planar waveguide includes a first diffractive optical element (DOE) positioned at a first lateral position and a third color filter positioned at a third lateral position and operable to pass a third wavelength range. The eyepiece further includes a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane. The second planar waveguide includes a second DOE positioned at the third lateral position. The eyepiece additionally includes a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane. The third planar waveguide includes a third DOE positioned at the second lateral position.

[0260] In one aspect, the substrate includes a first recess in which a first color filter can be disposed and a second recess in which a second color filter can be disposed. The first planar waveguide can include a recess in which a third color filter can be disposed. The first color filter can be operable to transmit a first wavelength range and attenuate a second wavelength range and a third wavelength range. The second color filter can be operable to transmit a second wavelength range and attenuate the first wavelength range and the third wavelength range. The third color filter can be operable to transmit a third wavelength range and attenuate the first wavelength range and the second wavelength range.

[0261] In one aspect, at least one of the first color filter, the second color filter, or the third color filter includes an absorptive color filter. In a plan view, the second color filter can be positioned opposite the third color filter about the optical axis. The eyepiece can further include a fourth planar waveguide positioned in a fourth lateral plane adjacent to the third lateral plane, a fifth planar waveguide positioned in a fifth lateral plane adjacent to the fourth lateral plane, and a sixth planar waveguide positioned in a sixth lateral plane adjacent to the fifth lateral plane. The fourth planar waveguide can include a fourth diffractive optical element (DOE) positioned at the fourth lateral position, the fifth planar waveguide can include a fifth DOE positioned at the fifth lateral position, and the sixth planar waveguide can include a sixth DOE positioned at the sixth lateral position. The eyepiece can also include a sixth color filter disposed at a sixth lateral position and operable to pass a third wavelength range. In plan view, the sixth color filter can be positioned opposite the first color filter about the optical axis. The first wavelength range can include 600 nm to 700 nm, the second wavelength range can include 500 nm to 600 nm, and the third wavelength range can include 400 nm to 500 nm.

[0262] According to one aspect of the present disclosure, an eyepiece for projecting an image onto a viewer's eye is provided. The eyepiece includes a first lateral plane positioned within a first planar waveguide. The first planar waveguide includes a first diffractive optical element (DOE) disposed at a first lateral position and defining a first boundary enclosing a first surface area. The eyepiece also includes a second planar waveguide positioned within a second lateral plane adjacent to the first lateral plane. The second planar waveguide includes a second DOE disposed at a second lateral position outside the first boundary. The second planar waveguide defines a second boundary enclosing a second surface area. The eyepiece further includes a third planar waveguide positioned within a third lateral plane adjacent to the second lateral plane. The third planar waveguide includes a third DOE disposed at a third lateral position outside the first boundary and outside the second boundary. The first DOE can be disposed in a peripheral region of the first boundary. The first boundary can include one or more peripheral cutouts. The first boundary can include one or more central orifices.

[0263] According to one aspect of the present disclosure, a method for coupling light into an eyepiece including a plurality of planar waveguides is provided. The method includes directing a first beam including a first wavelength to impinge on the eyepiece, coupling at least a portion of the first beam into a first planar waveguide of the plurality of planar waveguides, directing a second beam including a second wavelength to impinge on the eyepiece, and coupling at least a portion of the second beam into a second planar waveguide of the plurality of planar waveguides. The method also includes directing a third beam including a third wavelength to impinge on the eyepiece, passing a transmitted portion of the third beam through an optical filter, and coupling at least a portion of the transmitted portion of the third beam into a third planar waveguide of the plurality of planar waveguides.

[0264] According to one aspect of the present disclosure, a method for coupling light into an eyepiece including a plurality of planar waveguides, each having a diffractive optical element associated with the plurality of planar waveguides, is provided. The method includes directing a first beam including a first wavelength, a second beam including a second wavelength, and a third beam including a third wavelength to impinge on the eyepiece at a first lateral position, coupling at least a portion of the first beam, at least a portion of the second beam, and at least a portion of the third beam into a first planar waveguide of the plurality of planar waveguides, and attenuating at least a portion of the second beam and at least a portion of the third beam. The method also includes coupling at least a second portion of the second beam into a second planar waveguide of the plurality of planar waveguides, passing a transmitted portion of the third beam through an optical filter, and coupling at least a portion of the transmitted portion of the third beam into a third planar waveguide of the plurality of planar waveguides.

[0265] In one aspect, the diffractive optical elements associated with each of the plurality of planar waveguides are aligned at a first lateral position. The method can further include reflecting the reflected portion of the third beam from the optical filter. The method can also include coupling at least a portion of the reflected portion of the third beam into a second planar waveguide.

[0266] According to one aspect of the present disclosure, an image display system is provided. The image display system includes a single white light source for providing illuminating white light and an LCOS (liquid crystal on silicon) image projection device configured to receive the illuminating white light and sequentially project grayscale images at an optical pupil. Each grayscale image is configured to select a pixel for each of three colors. The image display system also includes a shutter having three shutter regions configured to divide the optical pupil into three sub-pupils for the three colors, and a filter having three filter regions aligned with the three shutter regions. Each filter region has a color filter for one of the colors. The shutter and filter are synchronized with the LCOS image projection device to sequentially project images in each of the three colors at a corresponding sub-pupil. The image display system further includes an eyepiece having three waveguide layers, each of which includes a diffractive optical element (DOE) aligned with a corresponding sub-pupil and configured to receive image light in one of the colors, and the eyepiece can be configured to project color images to a viewer.

[0267] In one aspect, the single white light source can include a white light emitting diode (LED) light source. The single white light source can be configured to project a square or rectangular illumination light beam. The shutter can include a liquid crystal (LC) shutter. The three shutter regions can be rectangular regions adjacent to each other. The three filter regions can be rectangular regions adjacent to each other. The three sub-pupils can be rectangular regions adjacent to each other.

[0268] The DOE in each waveguide layer can be configured to receive image light in one of the colors, diffract the image light into the waveguide layer, and propagate the image light in the waveguide layer in a propagation direction by total internal reflection (TIR). The DOE in each waveguide layer can be aligned with a corresponding sub-pupil for receiving the image light in one of the colors. The DOEs in the waveguide layers can be spatially displaced from each other. The DOE in each waveguide layer has a rectangular shape and is elongated in a direction perpendicular to the propagation direction.

[0269] According to an aspect of the present disclosure, an image display system is provided. The image display system includes a light source for providing color-sequential illumination. The light source has a plurality of color LED light sources. The image display system also includes an LCOS (liquid crystal on silicon) image projection device configured to receive illumination from the plurality of color LED light sources and sequentially project color image light at an optical pupil for each of three colors. The optical pupil is characterized by a pupil area and includes a plurality of non-overlapping sub-pupils. Each of the plurality of non-overlapping pupils is characterized by a sub-pupil area. Each of the plurality of LED light sources can be configured to illuminate one of the plurality of non-overlapping sub-pupils. The sum of the sub-pupil areas can be substantially equal to the pupil area. The sum of the sub-pupil areas can be equal to the pupil area.

[0270] In certain aspects, the optical pupil has a circular shape, and the plurality of LED light sources can each be configured to illuminate a sub-pupil that can be a sector of the optical pupil. In certain aspects, the optical pupil has a square or rectangular shape, and the plurality of LED light sources can each be configured to illuminate a sub-pupil that can be a rectangular portion of the optical pupil. In certain aspects, the optical pupil has a square or rectangular shape, and the plurality of LED light sources can include a red LED, a blue LED, and a green LED, each configured to illuminate a sub-pupil that can be a rectangular portion of the optical pupil. In certain aspects, the optical pupil has a circular shape, and the plurality of LED light sources can include two red LEDs, two blue LEDs, and two green LEDs, each configured to illuminate a sub-pupil that can be a sector of the optical pupil. In certain aspects, the optical pupil has a square or rectangular shape, and the plurality of LED light sources can include two red LEDs, two blue LEDs, and two green LEDs, each configured to illuminate a sub-pupil that can be a rectangular portion of the optical pupil.

[0271] The three colors can be three primary colors, and the plurality of LED light sources can include one or more LED light sources in each of the three primary colors. Each of the plurality of LED light sources can include an LED chip and a concentrator, for example, a compound parabolic concentrator (CPC).

[0272] According to one aspect of the present disclosure, an image display system is provided. The image display system includes a light source for providing color-sequential illumination, the light source having a plurality of LED light sources, and an LCOS (liquid crystal on silicon) image projection device configured to receive illumination from the plurality of color LED light sources and sequentially project color image light at an optical pupil for each of three colors. The optical pupil includes a plurality of non-overlapping sub-pupils corresponding to the plurality of LED light sources. The image display system also includes an eyepiece having a plurality of waveguide layers. Each waveguide layer includes a diffractive optical element (DOE) aligned with a corresponding sub-pupil for receiving image light from the corresponding LED light source. The LCOS image projection device generates higher diffraction orders from each of the plurality of LED light sources, and the DOE in each waveguide is positioned at a location displaced from the image from the higher diffraction orders.

[0273] According to one aspect of the present disclosure, an image display system is provided. The image display system includes a white light source for providing illumination white light, an LCOS (liquid crystal on silicon) image projection device configured to receive the illumination white light and sequentially project grayscale images at an optical pupil for each of three colors, and a shutter having multiple shutter regions configured to divide the optical pupil into a corresponding plurality of sub-pupils, one for each color. The image display system also includes a filter having multiple filter regions. Each filter region has a color filter for one of the colors, and each of the multiple filter regions is aligned with a corresponding one of the multiple shutter regions. The shutter is synchronized with the LCOS image projection device to sequentially project images in each of the three colors at one of the multiple sub-pupils.

[0274] The white light source can include a single white light source. The shutter can include six shutter regions, and the filter can include six filter regions, with the shutter and filter aligned to form six sub-pupils. The image display system can further include an eyepiece having six waveguide layers, each waveguide layer including a diffractive optical element (DOE) aligned with a corresponding sub-pupil for receiving image light in one of the colors. The eyepiece can be configured to project color images at two depth planes.

[0275] According to one aspect of the present disclosure, an image display system is provided. The image display system includes a plurality of white LED light sources for providing illumination white light and an LCOS (liquid crystal on silicon) image projection device configured to receive the illumination white light and sequentially project grayscale images at an optical pupil for each of three colors. The image display system also includes a shutter device having a plurality of shutter regions configured to divide the optical pupil into a corresponding plurality of sub-pupils, one for each color. The image display system further includes a filter having a plurality of filter regions, each filter region having a color filter for one of the colors. Each of the plurality of filter regions is aligned with a corresponding one of the plurality of shutter regions. The shutter is synchronized with the LCOS image projection device to sequentially project images in each of the three colors at one of the plurality of sub-pupils.

[0276] The plurality of white LED light sources may include a first white LED light source and a second white LED light source. The shutter device may have three shutter regions. The filter may have six color filter regions: two red color filter regions, two green color filter regions, and two blue color filter regions. The first red color filter region, the first green color filter region, and the first blue color filter region may be configured to receive light from the first white LED light source. The second red color filter region, the second green color filter region, and the second blue color filter region may be configured to receive light from the second white LED light source. The optical pupil may include three subpixels. The optical pupil may include six subpixels. The first and second red color filter regions may be aligned with two different shutter regions, the first and second green color filter regions may be aligned with two different shutter regions, and the first and second blue color filter regions may be aligned with two different shutter regions.

[0277] The plurality of white LED light sources can include a first white LED light source and a second white LED light source. The shutter device can include a first shutter and a second shutter, each shutter including three shutter regions. In one aspect, the filter can include six color filter regions: two red color filter regions, two green color filter regions, and two blue color filter regions. The first red color filter region, the first green color filter region, and the first blue color filter region can be configured to receive light from the first white LED light source. The second red color filter region, the second green color filter region, and the second blue color filter region can be configured to receive light from the second white LED light source. The optical pupil can include three subpixels. The optical pupil can include six subpixels. The first and second red color filter regions can be aligned with two different shutter regions, the first and second green color filter regions can be aligned with two different shutter regions, and the first and second blue color filter regions can be aligned with two different shutter regions.

[0278] According to one aspect of the present disclosure, an image display system is provided. The image display system includes a single white light source for providing illuminating white light and an LCOS (liquid crystal on silicon) image projection device configured to receive the illuminating white light and project a full-color image at an optical pupil. The image display system also includes a shutter having three shutter regions configured to divide the optical pupil into three sub-pupils. Each of the three sub-pupils is associated with one of three colors. The image display system further includes a filter having three filter regions, each filter region having a color filter for one of the three colors, and the three filter regions respectively matched to the three shutter regions. The image display system is configured to sequentially project images in each of the three colors at a separate sub-pupil.

[0279] In one aspect, the image display system further includes an eyepiece having three waveguide layers. Each waveguide layer includes a diffractive optical element (DOE) aligned with a corresponding sub-pupil for receiving image light in one of the colors. The eyepiece can be configured to project a color image to a viewer. The single white light source can be configured to project a square or rectangular illumination light beam. The three shutter areas can be rectangular areas adjacent to each other. The LCOS image projection device can include three LCOS panels and process the images in the three colors to provide a combined full-color image.

[0280] According to one aspect of the present disclosure, an image display system is provided. The image display system includes a white light source for providing illumination white light, an LCOS (liquid crystal on silicon)-based image projection device configured to receive the illumination white light and project an image at an optical pupil, and a shutter having multiple shutter regions configured to divide the optical pupil into multiple sub-pupils, one for each of multiple colors. The image display system also includes a filter having multiple filter regions, each filter region having a color filter for one of the multiple colors, and each of the multiple filter regions being matched to a corresponding one of the multiple shutter regions. The shutter is synchronized with the LCOS image projection device to sequentially project an image in each of the multiple colors at one of the multiple sub-pupils.

[0281] The multiple sub-pupils can be configured to fill the optical pupil. The image display system can further include an eyepiece having multiple waveguide layers, each waveguide layer including a diffractive optical element (DOE) aligned with a corresponding sub-pupil for receiving image light in one of the multiple colors. The eyepiece can be configured to project a color image to a viewer. The multiple colors can be three primary colors, and the LCOS image projection device can be configured to receive illuminating white light and sequentially project grayscale images at the optical pupil for each of the three primary colors. The LCOS image projection device can include three LCOS panels, each associated with one of the three primary colors. The LCOS image projection device can be configured to receive illuminating white light and project a full-color image at the optical pupil.

[0282] According to an aspect of the present disclosure, a method for displaying images is provided. The method includes providing a white light source and an image projector, receiving white light from the white light source at the image projector, and sequentially projecting grayscale images at an optical pupil. Each grayscale image is configured to select pixels for a corresponding one of three colors. The method also includes providing a shutter and color filters to divide the optical pupil into three sub-pupils for the three colors, synchronizing the shutter and color filters with the grayscale images to sequentially project the images in each of the three colors at the corresponding sub-pupils, providing an eyepiece with three waveguide layers, and sequentially receiving the images in each of the three colors at the corresponding waveguide layers to project the images to a viewer.

[0283] In one aspect, the white light source includes a single white LED light source. The method can further include receiving the white light and sequentially projecting grayscale images at the optical pupil using an LCOS (liquid crystal on silicon) image projection device. The shutter can include a liquid crystal (LC) shutter having three shutter regions for dividing the optical pupil into three sub-pupils. The color filter can include three filter regions, each filter region including a color filter for one of three colors.

[0284] According to an aspect of the present disclosure, a method for displaying an image is provided. The method includes providing a white light source and an image projector, receiving white light from the white light source at the image projector, and projecting an image at an optical pupil. The method also includes providing a shutter and color filters to divide the optical pupil into multiple sub-pupils, synchronizing the shutter and color filters with the image from the image projector to sequentially project images in each of three colors at corresponding sub-pupils, providing an eyepiece having multiple waveguide layers, and sequentially receiving the images in each of the three colors at corresponding waveguide layers to project the color images to a viewer.

[0285] The image projector can be configured to sequentially project grayscale images at the optical pupil, each grayscale image configured to select pixels for each of three colors. In one aspect, synchronizing the shutter with the color filter with the grayscale images can include projecting a single color image for each subpixel of each grayscale image. The image projector can be configured to project a full-color image at the optical pupil. In one aspect, synchronizing the shutter and color filter with the image from the image projector can include projecting three single color images for three corresponding subpixels of each full-color image from the image projector.

[0286] It should be understood that the examples and embodiments described herein are for illustrative purposes only, and that various modifications or changes in light thereof will be suggested to those skilled in the art and are to be included within the spirit and scope of the present application and the appended claims.

[0287] Upon perusal of this disclosure, those skilled in the art will still recognize additional alternative structural and functional designs for systems and processes for motion-based content navigation through the principles disclosed herein. Thus, while particular embodiments and applications have been illustrated and described, it should be understood that the disclosed embodiments are not limited to the precise structure and components disclosed herein. Various modifications, changes, and variations, which will be apparent to those skilled in the art, can be made in the arrangement, operation, and details of the methods and apparatus disclosed herein without departing from the spirit and scope, as defined in the appended claims.

Claims

1. An eyepiece for projecting an image onto a viewer's eye, the eyepiece comprising: a substrate positioned in a substrate lateral plane; a set of color filters disposed on the substrate, the set of color filters comprising: a first color filter disposed at a first lateral position and operable to pass a first range of wavelengths; a second color filter disposed at a second lateral position and operable to pass a second range of wavelengths; a third color filter disposed at a third lateral position and operable to pass a third range of wavelengths; and Equipped with In a plan view, the first color filter, the second color filter, and the third color filter are positioned around a specific point on the substrate, and the second color filter is positioned opposite to the third color filter with the specific point as the center. A set of color filters, a first planar waveguide positioned in a first lateral plane adjacent to the substrate lateral plane, the first planar waveguide comprising a first diffractive optical element (DOE) disposed at the first lateral position; a second planar waveguide positioned in a second lateral plane adjacent to the first lateral plane, the second planar waveguide comprising a second DOE disposed at the second lateral position; a third planar waveguide positioned in a third lateral plane adjacent to the second lateral plane, the third planar waveguide comprising a third DOE disposed at the third lateral position; An eyepiece comprising:

2. 2. The eyepiece of claim 1, wherein the first color filter comprises a first photoresist operable to transmit the first wavelength range and attenuate the second wavelength range and the third wavelength range.

3. 2. The eyepiece of claim 1, wherein the second color filter comprises a second photoresist operable to transmit the second wavelength range and attenuate the first wavelength range and the third wavelength range.

4. 2. The eyepiece of claim 1, wherein the third color filter comprises a third photoresist operable to transmit the third wavelength range and attenuate the first wavelength range and the second wavelength range.

5. The eyepiece of claim 1 , wherein at least one of the first color filter, the second color filter, or the third color filter comprises ultraviolet ink.

6. further comprising a fourth color filter disposed at a fourth lateral position and operable to pass the first wavelength range; 2. The eyepiece of claim 1, wherein, in a plan view, the first color filter, the second color filter, the third color filter, and the fourth color filter are positioned around a specific point on the substrate, and the first color filter is positioned adjacent to the fourth color filter.

7. the substrate has a first side and a second side; the set of color filters is disposed on a first side of the substrate; a second side of the substrate facing the first planar waveguide; 10. The eyepiece of claim 1.

8. the substrate has a first side and a second side; the set of color filters is disposed on a second side of the substrate; a second side of the substrate facing the first planar waveguide; 10. The eyepiece of claim 1.

9. a fourth color filter disposed on the substrate at a fourth lateral position and operable to pass the first wavelength range; a fifth color filter disposed at a fifth lateral position and operable to pass the second wavelength range; The eyepiece of claim 1 further comprising:

10. 10. The eyepiece of claim 9, wherein, in a plan view, the first color filter, the second color filter, the third color filter, the fourth color filter, and the fifth color filter are positioned around a specific point on the substrate, and the fifth color filter is positioned opposite the first color filter with the specific point as the center.

11. a fourth planar waveguide positioned in a fourth lateral plane adjacent to the third lateral plane, the fourth planar waveguide comprising a fourth diffractive optical element (DOE) disposed at the fourth lateral position; a fifth planar waveguide positioned in a fifth lateral plane adjacent to the fourth lateral plane, the fifth planar waveguide comprising a fifth DOE disposed at the fifth lateral position; a sixth planar waveguide positioned in a sixth lateral plane adjacent to the fifth lateral plane, the sixth planar waveguide comprising a sixth DOE disposed at a sixth lateral position; The eyepiece of claim 9 further comprising:

12. 10. The eyepiece of claim 9, further comprising a sixth color filter positioned at a sixth lateral position and operable to pass the third wavelength range.

13. 13. The eyepiece of claim 12, wherein, in a plan view, the first color filter, the second color filter, the third color filter, the fourth color filter, the fifth color filter, and the sixth color filter are positioned around a specific point on the substrate, and the fourth color filter is positioned opposite the sixth color filter with the specific point as the center.

14. 2. The eyepiece of claim 1, wherein the first wavelength range includes 600 nm to 700 nm, the second wavelength range includes 500 nm to 600 nm, and the third wavelength range includes 400 nm to 500 nm.

15. 10. The eyepiece of claim 1, further comprising a set of spatially displaced light sources including a first light source, a second light source, and a third light source, wherein the first wavelength range corresponds to the first light source, the second wavelength range corresponds to the second light source, and the third wavelength range corresponds to the third light source.

Images