Architectures and methods for outputting light of different wavelengths out of waveguides

Abstract

To provide architectures for selectively outputting light for forming images, the light having different wavelengths and being output with low levels of crosstalk.SOLUTION: In some embodiments, light is incoupled into a waveguide and deflected to propagate in different directions, depending on wavelengths. The incident light is then outcoupled by outcoupling optical elements that outcouple light based on the direction of propagation of the light. In some other embodiments, color filters are between a waveguide and outcoupling optical elements. The color filters limit the wavelengths of light acting on and outcoupled by the outcoupling elements. In yet other embodiments, a different waveguide is provided for each range of wavelengths to be outputted. Incoupling optical elements selectively incouple light of the appropriate range of wavelengths into a corresponding waveguide, from which the light is outcoupled.SELECTED DRAWING: Figure 9A

Description

[Technical field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 057,165, entitled "Virtual and Augmented Reality Systems and Methods," filed Sep. 29, 2014, which is incorporated herein by reference in its entirety.

[0002] This application incorporates by reference the following patent applications in their entireties: U.S. Patent Application No. 14 / 331,218 (Attorney Docket No. 20020.00); U.S. Provisional Patent Application No. 62 / 012,273 (Attorney Docket No. 30019.00); and U.S. Provisional Patent Application No. 62 / 005,807 (Attorney Docket No. 30016.00). [Background technology]

[0003] This application relates to virtual and augmented reality imaging and visualization systems.

[0004] Modern computing and display technologies have led to the development of systems for so-called "virtual reality" or "augmented reality" experiences, which present digitally generated images or portions thereof to a user in a way that appears or is perceived as real. Virtual reality or "VR" scenarios typically present digital or virtual image information without transparency to other real-world image inputs. Augmented reality or "AR" scenarios typically present digital or virtual image information as an augmentation to a real-world image of the user's surroundings. For example, referring to FIG. 1, an augmented reality scene is shown in which a user of AR technology views a real-world park-like situation 1100 with people, trees, and background buildings, and a concrete foundation 1120. In addition to these, a user of the AR technology perceives as "seeing" a robotic figure 1110 standing on a real-world base 1120, and a cartoonish avatar character 1130 that appears to be an anthropomorphic buzzing bee, even though these elements 1130, 1110 do not exist in the real world. Because of the complexity of the human visual system, creating a VR or AR technology that presents rich virtual image elements among other virtual or real-world image elements in a way that feels comfortable and natural is a difficult challenge.

[0005] The systems and methods of the present invention address various challenges related to VR and AR technologies. Summary of the Invention [Means for solving the problem]

[0006] (First embodiment) a waveguide having a first major surface and a second major surface, the waveguide being configured to propagate light between the first and second major surfaces by total internal reflection; an input coupling optical element configured to couple incident light into the waveguide along a first direction at a first plurality of wavelengths and to couple incident light into the waveguide along a second direction at one or more second wavelengths, wherein the coupled light at the first plurality of wavelengths propagates through the waveguide along the first direction by total internal reflection and the coupled light at the one or more second wavelengths propagates through the waveguide along the second direction by total internal reflection; first and second out-coupling optical elements configured to out-couple the in-coupled light from the waveguide; An optical system comprising:

[0007] Second embodiment 13. The optical system of a first embodiment, wherein the input coupling optical element comprises one or more diffractive optical elements.

[0008] (Third embodiment) The optical system of a second embodiment, wherein the one or more diffractive optical elements comprise one or more of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

[0009] (Fourth embodiment) The optical system of a third embodiment, wherein said switchable diffractive optical element is a switchable polymer dispersed liquid crystal (PDLC) grating.

[0010] Fifth embodiment a first wavelength selective reflector configured to reflect incoupled light of the first plurality of wavelengths propagating along the first direction and pass light of wavelengths other than the first plurality of wavelengths; The optical system of any of the first to fourth embodiments, further comprising a second wavelength selective reflector configured to reflect in-coupled light of the one or more second wavelengths propagating along the second direction, and passing light of wavelengths other than the one or more second wavelengths.

[0011] Sixth embodiment a first absorber configured to absorb light incoupled through the first wavelength selective reflector; The optical system of the fifth embodiment, further comprising: a second absorber configured to absorb in-coupled light through the second wavelength selective reflector.

[0012] Seventh embodiment 10. The optical system of embodiment 5, wherein said first and second wavelength selective reflectors are dichroic filters.

[0013] Eighth embodiment The optical system of any one of the first to seventh embodiments, wherein the first plurality of wavelengths of light includes red light and blue light.

[0014] Ninth embodiment The optical system of any one of the first to eighth embodiments, wherein the light of the one or more second wavelengths includes green light.

[0015] (Tenth embodiment) a first light distribution element configured to receive the in-coupled light of the first plurality of wavelengths traveling along the first direction and distribute the light of the first plurality of wavelengths to the first out-coupling optical element; The optical system of any of the first to ninth embodiments, further comprising a second light distribution element configured to receive in-coupled light of the one or more second wavelengths traveling along the second direction and distribute light of the one or more second wavelengths to the second out-coupling optical element.

[0016] (Eleventh embodiment) The optical system of the tenth embodiment, wherein the first and second light distribution elements comprise one or more diffractive optical elements.

[0017] (Twelfth embodiment) 11. The optical system of embodiment 1, wherein the one or more diffractive optical elements comprise one or more gratings.

[0018] Thirteenth embodiment The optical system of any one of the tenth to twelfth embodiments, wherein the first light distribution element is configured to redirect light of the first plurality of wavelengths to propagate within the waveguide in a direction different from a direction that the second light distribution element is configured to redirect light of the one or more second wavelengths.

[0019] (Fourteenth embodiment) The optical system of any one of the tenth to thirteenth embodiments, wherein the first light distribution element is configured to redirect light of the first plurality of wavelengths propagating in the waveguide into the second direction, and the second light distribution element is configured to redirect light of the one or more second wavelengths propagating in the waveguide into the first direction.

[0020] Fifteenth embodiment The optical system of any of the tenth to fourteenth embodiments, wherein the first and second light distribution elements are orthogonal pupil expanders.

[0021] Sixteenth embodiment The optical system of any one of the first to fifteenth embodiments, wherein the first output coupling optical element comprises one or more gratings configured to output couple light of the first plurality of wavelengths from the waveguide, and the second output coupling optical element comprises one or more gratings configured to output couple light of the one or more second wavelengths from the waveguide.

[0022] (Seventeenth embodiment) An optical system of a sixteenth embodiment, wherein the one or more gratings of the first output coupling optical element are provided on the first main surface of the waveguide, and the one or more gratings of the second output coupling optical element are provided on the second main surface of the waveguide.

[0023] (Eighteenth embodiment) 16. The optical system of embodiment 16, wherein the one or more gratings of the first output coupling optical element and the one or more gratings of the second output coupling optical element are provided on the same major surface of the waveguide.

[0024] (19th embodiment) The optical system of any one of the sixteenth to eighteenth embodiments, wherein the one or more gratings of the first output coupling optical element comprise one or more of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

[0025] (Twentieth embodiment) 20. The optical system of embodiment 19, wherein the switchable diffractive optical element comprises a switchable polymer dispersed liquid crystal (PDLC) grating.

[0026] (21st embodiment) 1. An optical system comprising a plurality of stacked waveguides, Each of the waveguides has a first major surface and a second major surface, each of the waveguides being configured to propagate light by total internal reflection between the first and second major surfaces, and each of the waveguides further comprising: an input coupling optical element configured to couple incident light into the waveguide along a first direction at a first plurality of wavelengths and to couple incident light into the waveguide along a second direction at one or more second wavelengths; an out-coupling optical element configured to out-couple the in-coupled light from the waveguide; An optical system comprising:

[0027] (Twenty-second embodiment) 21. The optical system of embodiment 2, wherein each of the waveguides has an associated depth plane, and each of the waveguides is configured to generate an image that appears to originate from the associated depth plane.

[0028] (Twenty-third embodiment) The optical system of the twenty-first to twenty-second embodiments, wherein different said waveguides have different associated depth planes.

[0029] (Twenty-fourth embodiment) The optical system of any one of the twenty-first to twenty-third embodiments, wherein the output coupling optical elements corresponding to different depth planes have different refractive powers, and the divergence angle of the light exiting for each depth plane is different.

[0030] (Twenty-fifth embodiment) a waveguide having a first major surface and a second major surface; an input coupling optical element configured to input couple incident light into the waveguide; a first wavelength-selective filter provided on the first main surface, the first wavelength-selective filter having a first rear surface adjacent to the first main surface and a first front surface opposite to the first rear surface; transmitting the coupled light of a first plurality of wavelengths through the first rear surface and reflecting a portion of the transmitted light of the first plurality of wavelengths from the first front surface; the first wavelength selective filter configured to reflect the coupled light at other wavelengths; a first output coupling optical element disposed on the first wavelength selective filter, the first output coupling optical element configured to output couple the in-coupled light of the first plurality of wavelengths transmitted through the first wavelength selective filter; An optical system comprising:

[0031] (Twenty-sixth embodiment) a second wavelength-selective filter provided on the second main surface, the second wavelength-selective filter having a second rear surface adjacent to the second main surface and a second front surface opposite to the second rear surface; transmitting light at one or more second wavelengths different from the first plurality of wavelengths coupled in through the second rear surface; and reflecting a portion of the transmitted light at the one or more second wavelengths from the second front surface; the second wavelength selective filter configured to reflect the coupled light at the first plurality of wavelengths; a second output coupling optical element disposed on the second wavelength selective filter, the second output coupling optical element configured to output couple the in-coupled light of the one or more second wavelengths transmitted through the second wavelength selective filter; and The optical system of a twenty-fifth embodiment, further comprising:

[0032] (Twenty-seventh embodiment) 26. The optical system of embodiment 2, wherein the first and second wavelength selective filters comprise dichroic filters.

[0033] (Twenty-eighth embodiment) The optical system of any one of the twenty-sixth to twenty-seventh embodiments, wherein the first and second wavelength selective filters are configured to transmit light of the first plurality of wavelengths and the one or more second wavelengths incident at an angle between 0 degrees and 20 degrees with respect to a normal to the corresponding first or second major surface of the waveguide.

[0034] (Twenty-ninth embodiment) The optical system of any one of the twenty-sixth to twenty-eighth embodiments, wherein the light of the one or more second wavelengths includes green light.

[0035] (Thirtieth embodiment) receiving coupled light of the first plurality of wavelengths and the second one or more wavelengths from the input coupling optical element; Distributing the light at the first plurality of wavelengths and the one or more second wavelengths to the first and second output coupling optical elements. The optical system of any one of the twenty-sixth to twenty-ninth embodiments, further comprising a light distribution element configured to:

[0036] (Thirty-first embodiment) The optical system of a 30th embodiment, wherein the light distribution element comprises one or more diffractive optical elements.

[0037] (Thirty-second embodiment) The optical system of the 30th to 31st embodiments, wherein the light distribution element is an orthogonal pupil expander.

[0038] (Thirty-third embodiment) The optical system of any one of the 30th to 32nd embodiments, wherein a first portion of the light of the first plurality of wavelengths is reflected at the first front surface of the first wavelength selective filter and a second portion of the light of the first plurality of wavelengths is redirected by the light redistribution element.

[0039] (Thirty-fourth embodiment) 33. The optical system of embodiment 33, wherein the first portion of the light of the first plurality of wavelengths is incident on the first wavelength selective filter after being reflected by the second major surface, and a portion of the first portion of light is redirected by the light redistribution element.

[0040] (Thirty-fifth embodiment) An optical system of any of embodiments 30 to 34, wherein a third portion of light at the one or more second wavelengths is reflected to the second front surface of the second wavelength selective filter, and a fourth portion of light at the one or more second wavelengths is redirected by the light redistribution element.

[0041] (Thirty-sixth embodiment) An optical system of a 35th embodiment, wherein the third portion of light at the one or more second wavelengths is incident on the second wavelength selective filter after being reflected by the first principal surface, and a portion of the third portion of light is redirected by the light redistribution element.

[0042] (Thirty-seventh embodiment) the first output coupling optical element comprises one or more diffractive optical elements; The optical system of any one of the 26th to 36th embodiments, wherein the second output coupling optical element comprises one or more diffractive optical elements.

[0043] (Thirty-eighth embodiment) The optical system of a thirty-seventh embodiment, wherein the one or more diffractive optical elements of the first output coupling optical element comprise one or more of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

[0044] (Thirty-ninth embodiment) 38. The optical system of embodiment 38, wherein the switchable diffractive optical element comprises a switchable polymer dispersed liquid crystal (PDLC) grating.

[0045] (Fortieth embodiment) The optical system of a thirty-seventh embodiment, wherein the one or more diffractive optical elements of the second output coupling optical element comprise one or more of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

[0046] (Forty-first embodiment) 40. The optical system of embodiment 40, wherein the switchable diffractive optical element comprises a switchable polymer dispersed liquid crystal (PDLC) grating.

[0047] (Forty-second embodiment) The optical system of any one of the 25th to 41st embodiments, wherein the input coupling optical element comprises one or more diffractive optical elements.

[0048] (Forty-third embodiment) 42. The optical system of embodiment 42, wherein the one or more diffractive optical elements comprise one or more of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

[0049] (Forty-fourth embodiment) 43. The optical system of embodiment 43, wherein the switchable diffractive optical element comprises a switchable polymer dispersed liquid crystal (PDLC) grating.

[0050] (Forty-fifth embodiment) The optical system of any of the 25th to 44th embodiments, wherein the input coupling optical element comprises a prism.

[0051] (Forty-sixth embodiment) An optical system according to any one of the 25th to 45th embodiments, wherein the first plurality of wavelengths of light includes red light and blue light.

[0052] (Forty-seventh embodiment) A plurality of stacked waveguides, each of the waveguides having a first major surface and a second major surface, each waveguide further comprising: an input coupling optical element configured to input couple incident light into the waveguide; a first wavelength-selective filter provided on the first main surface, the first wavelength-selective filter having a first rear surface adjacent to the first main surface and a first front surface opposite to the first rear surface; the first wavelength-selective filter configured to transmit light of a first plurality of wavelengths coupled in through the first rear surface and to reflect a portion of the transmitted light of the first plurality of wavelengths from the first front surface; a first output coupling optical element disposed on the first wavelength selective filter, the first output coupling optical element configured to output couple the in-coupled light of the first plurality of wavelengths transmitted through the first wavelength selective filter; An optical system comprising:

[0053] (Forty-eighth embodiment) Each of the waveguides further comprises: a second wavelength-selective filter provided on the second main surface, the second wavelength-selective filter having a second rear surface adjacent to the second main surface and a second front surface opposite to the second rear surface; the second wavelength selective filter configured to transmit light at one or more second wavelengths different from the first plurality of wavelengths coupled in through the second rear surface and to reflect a portion of the transmitted light at the one or more second wavelengths at the second front surface; a second output coupling optical element disposed on the second wavelength selective filter, the second output coupling optical element configured to output couple the in-coupled light of the one or more second wavelengths transmitted through the second wavelength selective filter; and The optical system of the 47th embodiment, comprising:

[0054] (Forty-ninth embodiment) The optical system of any of the 47-48 embodiments, wherein each of the waveguides has an associated depth plane, and each of the waveguides is configured to generate an image that appears to originate from the associated depth plane.

[0055] (Fiftieth embodiment) The optical system of any of the forty-seventh to forty-ninth embodiments, wherein different said waveguides have different associated depth planes.

[0056] (Fifty-first embodiment) The optical system of any one of the 47th to 50th embodiments, wherein the output coupling optical elements corresponding to different depth planes have different refractive powers, such that the divergence angle of the light exiting for each depth plane is different.

[0057] (Fifty-second embodiment) Each of the waveguides comprises: receiving light of the first plurality of wavelengths and the one or more second wavelengths transmitted through the first and second wavelength selective filters; Distributing the light at the first plurality of wavelengths and the one or more second wavelengths to the first and second output coupling optical elements. The optical system of any of the forty-eighth to fifty-first embodiments, further comprising a light redistribution element configured to:

[0058] (Fifty-third embodiment) A plurality of stacked waveguides, each of said waveguides comprising: an input coupling optical element configured to selectively input couple incident light into the waveguide based on an attribute of the incident light; an output coupling optical element configured to output couple the light input coupled into the waveguide; An optical system comprising:

[0059] (Fifty-fourth embodiment) 53. The optical system of embodiment 53, wherein the attribute of the incident light is wavelength.

[0060] (Fifty-fifth embodiment) The optical system of any one of the 53rd to 54th embodiments, wherein the input coupling optical element is a wavelength selective reflector.

[0061] (Fifty-sixth embodiment) 55. The optical system of embodiment 55, wherein the wavelength selective reflector is a dichroic reflector.

[0062] (Fifty-seventh embodiment) An optical system of embodiments 55-56, wherein each of the waveguides is provided with a wavelength-selective reflector configured to reflect light in a different wavelength range than the wavelength-selective reflectors of other waveguides in the plurality of stacked waveguides.

[0063] (Fifty-eighth embodiment) The optical system of any one of embodiments 55 to 57, wherein each of the wavelength-selective reflectors is configured to reflect light in a wavelength range corresponding to a different color than the wavelength-selective reflectors of other waveguides in the plurality of stacked waveguides.

[0064] (Fifty-ninth embodiment) The optical system of any one of embodiments 53-58, wherein the plurality of stacked waveguides comprises three waveguides including a first waveguide configured to output red light, a second waveguide configured to output green light, and a third waveguide configured to output blue light.

[0065] (60th embodiment) The optical system of any one of the fifty-third to fifty-ninth embodiments, wherein the output coupling optical element is a diffractive optical element.

[0066] (61st embodiment) The optical system of a 60th embodiment, wherein the diffractive optical element comprises one or more of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

[0067] (62nd embodiment) 61. The optical system of embodiment 61, wherein the switchable diffractive optical element comprises a switchable polymer dispersed liquid crystal (PDLC) grating.

[0068] (63rd embodiment) The optical system of any one of embodiments 53-62, wherein each of the waveguides further comprises an angle-changing optical element configured to change the propagation angle of the incident light such that after collision, the incident light propagates at a shallower angle relative to the surface of the waveguide.

[0069] (64th embodiment) 63. The optical system of embodiment 63, wherein the angle-changing optical element is configured to change the focus of the incident light.

[0070] (65th embodiment) 63. The optical system of embodiment 63, wherein the angle-changing optical element is a prism.

[0071] (66th embodiment) 63. The optical system of embodiment 63, wherein the angle-changing optical element is a diffractive optical element.

[0072] (67th embodiment) An optical system according to any one of embodiments 53 to 66, wherein each of the waveguides further comprises a light distribution element, the input coupling optical element configured to direct light to the light distribution element, and the light distribution element configured to direct light to the output coupling optical element.

[0073] (68th embodiment) 67. The optical system of embodiment 67, wherein the light distribution element is an orthogonal pupil expander.

[0074] (69th embodiment) The optical system of any one of embodiments 67-68, wherein the light distribution element, the input coupling optical element, and the output coupling optical element are disposed on a surface of the waveguide.

[0075] (70th embodiment) The optical system of any one of embodiments 67-69, wherein the light distribution element comprises one or more of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

[0076] (71st embodiment) 70. The optical system of embodiment 70, wherein the switchable diffractive optical element comprises a switchable polymer dispersed liquid crystal (PDLC) grating.

[0077] (72nd embodiment) a plurality of stacked waveguide groups, each of the waveguide groups comprising a plurality of stacked waveguides, each of the waveguides comprising: an input coupling optical element configured to selectively input couple incident light into the waveguide based on an attribute of the incident light; an output coupling optical element configured to output couple the light input coupled into the waveguide; An optical system comprising:

[0078] (73rd embodiment) The optical system of embodiment 72, wherein each of the waveguides has an associated depth plane, each of the waveguides is configured to generate an image that appears to originate from the associated depth plane, and different groups of the waveguides have different associated depth planes.

[0079] (74th embodiment) The optical system of any one of the 72-73 embodiments, wherein the waveguides of each of the stacked waveguide groups have the same associated depth plane.

[0080] (75th embodiment) The optical system of any one of the seventy-second to seventy-fourth embodiments, wherein the output coupling optical element has a refractive power that produces a diverging light beam.

[0081] (76th embodiment) The optical system of any one of the 72-75 embodiments, wherein the output coupling optical elements corresponding to different depth planes have different refractive powers, and the divergence angle of the light exiting for each depth plane is different. [Brief description of the drawings]

[0082] [Figure 1]FIG. 1 is a diagram showing how an augmented reality (AR) user sees the AR through an AR device. [Diagram 2] FIG. 1 illustrates an example of a wearable display system. [Diagram 3] FIG. 1 illustrates a prior art display system that provides a user with a simulation of a three-dimensional image. [Figure 4] FIG. 1 illustrates an embodiment of a simulation of a three-dimensional image using multiple depth planes. [Figure 5A] FIG. 13 is a diagram showing the relationship between the radius of curvature and the radius of the focal point. [Figure 5B] FIG. 13 is a diagram showing the relationship between the radius of curvature and the radius of the focal point. [Figure 5C] FIG. 13 is a diagram showing the relationship between the radius of curvature and the radius of the focal point. [Figure 6] FIG. 13 illustrates an example of a group of waveguides for outputting image information to a user. [Figure 7] FIG. 13 shows an example of an exit beam output from a waveguide. [Figure 8] 1A-1C are schematic diagrams of images formed using different color components at each depth plane of a waveguide collection. [Figure 9A] 1 is a schematic diagram illustrating an example of a top view of a display device including a waveguide, input coupling optics, and output coupling optics. [Figure 9B] 9B is a schematic diagram showing an example of the AA' cross section of the display device shown in FIG. 9A. [Figure 9C] 1A to 1C are diagrams illustrating an example of a dichroic wavelength-selective filter and the operation of the dichroic wavelength-selective filter. [Figure 10A] 1 is a schematic diagram illustrating an example of a top view of a display device including a waveguide, an input coupling optical element, a wavelength selective filter, and first and second output coupling optical elements. [Figure 10B] 10B is a diagram showing an example of an AA' cross section of the display device shown in FIG. 10A. FIG. [Figure 10C] 10B is a diagram showing an example of an AA' cross section of the display device shown in FIG. 10A. FIG. [Figure 11A]FIG. 1 illustrates an example cross-sectional side view of multiple stacked waveguides, each configured to output light of a different wavelength or range of wavelengths. [Figure 11B] FIG. 11B is a diagram showing an example of a perspective view of the multiple stacked waveguides shown in FIG. 11A. [Figure 12A] 1A-1C show examples of side cross sections of waveguides having angle-changing optical elements that facilitate coupling light into the waveguide. [Figure 12B] 1A-1C show examples of side cross sections of waveguides having angle-changing optical elements that facilitate coupling light into the waveguide. [Figure 13] 1 is a graph showing the predicted effect of refractive index on visual field. These figures are intended to illustrate certain examples and are not intended to limit the scope of the invention. Like numbers refer to like parts throughout. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0083] VR and AR experiences are provided by a display system having a display that provides a viewer with images corresponding to multiple depth planes. The images may be different in each depth plane (e.g., scenes or objects may be displayed slightly differently) so that the viewer's eyes focus individually to provide the user with depth cues based on the eye's accommodation required to focus on different image features of a scene located at different depth planes and / or by seeing different image features in different depth planes that are out of focus. Depth cues in this context refer to solid depth perception.

[0084] In one configuration, full-color images can be formed at various depth planes by overlapping component images, each having a particular color component. For example, red, green, and blue images can be output to form a full-color image. As a result, each depth plane has multiple color component images associated with it. The color component images can be output using a waveguide that incouples light containing image information, distributes the incoupled light to a waveguide, and outcouples the light to a viewer.

[0085] Light may be coupled into the waveguide using input coupling optics such as diffractive elements, and out of the waveguide using output coupling optics, which may also be diffractive elements. Typically, a pair of input and output coupling optics may be used. However, such configurations may impair image quality. For example, such optics typically redirect a particular design wavelength most efficiently, and red, green, and blue component images fed into such a system may exhibit unwanted and significant cropping or misfocusing at some wavelengths (e.g., cropping and misfocusing may occur outside the design wavelengths). In addition, such input and output coupling optics may cause crosstalk and ghosting. In some cases, ghosted images may result when a diffractive optic optimized for one wavelength is hit by light of another wavelength. For example, a diffractive optic designed to place a green image at a depth plane one meter from the viewer may place a blue or red image at a depth plane closer or further away than one meter. Such crosstalk between depth planes may impair the viewer's depth perception and reduce image clarity.

[0086] In addition, color balance is adversely affected by the characteristic that input and output coupling optics, such as diffractive optics, redirect some wavelengths of light that they are not designed to redirect. Because a full-color image is formed using multiple color component images, the color accuracy and available color gamut of the full-color image depend on the ability to precisely control the amount of color component light that reaches the viewer. Crosstalk between different color component images is undesirable. For example, a full-color image can be formed using red, green, and blue component images. A red component image formed using red light that unintentionally contains green and blue light is undesirable, among other things, because it impairs the ability to precisely control the amount of green or blue light that creates the final full-color image. This reduces the ability to precisely control the ratio of the different color lights due to crosstalk, thereby reducing the color accuracy of the full-color image and reducing the range of colors that are created. In other words, a full-color image can be of high quality when each color component image is formed with "pure" color component light, rather than "dirty" color components that contain a range of unintended colors.

[0087] Embodiments of the present invention preferably have low levels of crosstalk and unintended output coupling.

[0088] In some embodiments, various architectures are provided for selectively outputting different wavelengths of light with low crosstalk levels. In some embodiments, light is in-coupled into a waveguide and redirected to propagate in different directions depending on the wavelength. The in-coupled light is out-coupled by one or more out-coupling optical elements that selectively out-couple the light based on the direction of light propagation. In some embodiments, color filters are provided between the waveguide and one or more out-coupling elements on a surface of the waveguide. The color filters act on the one or more out-coupling elements to limit the wavelengths of light that are out-coupled. In other embodiments, different waveguides are provided depending on the wavelength range or color to be output. The one or more in-coupling optical elements selectively in-couple light of the appropriate wavelength range into a corresponding waveguide, and the light is out-coupled from the waveguide.

[0089] In these various embodiments, the waveguides, as described, can form direct-view or near-eye display devices that receive input image information and generate an output image based on the input image information. These devices can be wearable and can be configured as glasses. The input image information received by the waveguides can be light of different wavelengths multiplexed together (e.g., red, green, and blue light) that is coupled into one or more waveguides. The coupled light is coupled out (or output) from the waveguides by one or more output coupling optical elements. The one or more output coupling optical elements can include diffractive structures, such as, for example, Analog Surface Relief gratings (ASR), Binary Surface Relief structures (BSR), Volume Holographic Optical Elements (VHOE), digital surface relief structures, and / or volume phase holographic materials (e.g., holograms recorded in volume phase holographic materials), or switchable diffractive optical elements (e.g., Polymer Dispersed Liquid Crystal (PDLC) gratings). It will be appreciated that analog surface relief gratings can combine multiple functions in a single structure which, through successive manufacturing steps (e.g., one function built on top of another), can have additional functions (e.g., the selective redirection of light of a particular wavelength or wavelength range and the selective redirection of light of another wavelength or wavelength range).

[0090] Various embodiments of the invention include one or more gratings (e.g., linear grooves). The gratings are configured such that light propagating along a direction substantially parallel to the grating does not change direction enough to be coupled out of the waveguide. In contrast, light propagating in a direction at an angle to the grating (e.g., perpendicular to the grooves) will strike the grating and be diffracted at an angle that does not satisfy the requirements for total internal reflection (TIR), resulting in the light being coupled out of the waveguide. In some embodiments, the waveguide may include one or more input coupling optical elements that redirect light in different directions according to the orientation of the corresponding diffractive structures.

[0091] Various embodiments described herein may include optical filters that transmit specific wavelengths of light. Filters can limit the wavelengths of light that impinge on or impinge on one or more out-coupling optical elements, thereby reducing the possibility of out-coupling light of unintended wavelengths.

[0092] It will be appreciated that embodiments of the invention may provide one or more of the following advantages. For example, as described, the out-coupling of light at unintended wavelengths is reduced, resulting in reduced ghosting as discussed above. This reduction or elimination of ghosting improves image clarity. Additionally, the reduced out-coupling of light at unintended wavelengths improves the color perception quality of images formed using the light. In some embodiments, the ability to specifically out-couple light at desired wavelengths or wavelength ranges allows images to have highly accurate color accuracy. Additionally, the high degree of control over the out-coupling of light at individual wavelengths allows for high control over the proportion of light at specific wavelengths in the final full color image, thereby increasing the range of colors displayed. The ability to precisely control the proportions of light at different wavelengths increases the number of repeatable combinations of possible color components, thereby increasing the number of colors (due to the composition of color components) that can be displayed. In some embodiments, light at multiple wavelengths or colors may be out-coupled from the same waveguide, improving manufacturability and yield, for example reducing the number of components used in the display system, thereby reducing the cost of the device, and reducing the structural and electrical complexity of the display system.

[0093] In general, embodiments of the present invention can be implemented as a display system. In some embodiments, the display system takes the form of glasses (e.g., wearable) and is suitable for providing a more immersive VR or AR experience. For example, a stacked waveguide (a single waveguide or a group of waveguides with multiple depth planes) may be configured to be in front of the user's or observer's eyes when worn. In some embodiments, multiple waveguides, for example two stacked groups of waveguides, each corresponding to an eye of the observer, may be used to provide different images to each eye.

[0094] FIG. 2 illustrates an example of a wearable display system 80. The display system 80 includes a display 62 and various mechanical and electronic modules and systems that support the functionality of the display 62. The display 62 is configured as glasses connected to a frame 64 that is wearable by a user or viewer 60 of the display system and that is configured to position the display 62 in front of the eyes of the user 60. In one embodiment, a speaker 66 is connected to the frame 64 and positioned near the ear canal of the user 60 (and in one embodiment, another speaker, not shown, is positioned near the other ear canal of the user to enable stereophonic control). In one embodiment, the display system may include one or more microphones 67 or other audio sensing devices. In one embodiment, the microphones may be configured to allow a user to provide input or commands to the system 80 (e.g., voice input command selections, natural language queries, etc.) and / or to enable voice communication with other people (e.g., other users of a similar display system).

[0095] 2, the display 62 is operatively connected 68, e.g., by wire or wirelessly, to a local processing data module 70 that may be, e.g., fixedly connected to the frame 64, fixedly connected to a helmet or hat worn by the user, embedded in headphones, or otherwise removably attached to the user 60 (e.g., in a backpack or belt-mounted configuration). The local processing data module 70 includes a hardware processor and digital memory, e.g., non-volatile memory (e.g., flash memory or hard disk drive), any of which may be used for processing, caching, and storing data. The data may include a) data acquired by sensors, e.g., image acquisition devices (e.g., cameras), microphones, inertial force measurement units, accelerometers, compasses, GPS units, wireless devices, and / or gyros, which may be, e.g., operatively connected to the frame 64 or attached to the user 60, and / or b) data acquired and / or processed using the remote processing module 72 and / or remote data repository 74, possibly en route to the display 62 after such processing or acquisition. The local processed data module 70 is operatively connected to a remote processing module 72 and a remote data repository 74 by communication links 76, 78, e.g., wired or wireless communication links, which are operatively connected to each other and available as resources to the local processed data module 70. In one embodiment, the local processed data module 70 may include one or more image capture devices, microphones, inertial force measurement units, accelerometers, compasses, GPS units, wireless devices, and / or gyros. In one embodiment, one or more of these sensors may be mounted on the frame 64 or may be stand-alone structures that communicate with the local processed data module 70 via wired or wireless communication paths.

[0096] 2, in one embodiment, the remote processing module 72 may include one or more processors configured to analyze and process the data and / or image information. In one embodiment, the remote data repository 74 may be a digital data storage facility accessible through the Internet or other network configuration in a "cloud" resource configuration. In one embodiment, all data is stored in the local processing data module and all computations are performed there, allowing for autonomous use without the remote module.

[0097] The perception of an image being "three-dimensional" or "3D" can be achieved by presenting a slightly different image to each eye of the viewer. Figure 3 shows a prior art display system that simulates a three-dimensional image for a user. Two different images 5, 7 are output to the user - one for each eye 4, 6. The images 5, 7 are spaced a distance 10 from the eyes 4, 6 along an optical or Z axis that is parallel to the viewer's line of sight. The images 5, 7 are flat, and the eyes 4, 6 can focus on them by assuming a single adaptation state. This combination of the images 5, 7 to provide the perception of depth in the combined image relies on the human visual system.

[0098] Fortunately, however, the human visual system is more complex and providing realistic depth perception is more challenging. For example, many viewers of conventional "3D" display systems find them uncomfortable or are unable to perceive depth at all. Without wishing to be bound by theory, it is believed that a viewer of an object perceives the object as "three-dimensional" through a combination of convergence and accommodation. Vergence in both eyes (i.e., the rotational movement of the pupils moving closer and farther apart to focus and gaze at an object) is closely related to the focusing (or "accommodation") of the eye's lenses. Under normal conditions, changing the focal length of the eye's lenses to change focus from one object at a different distance to another, or accommodating the eye, also automatically causes convergence to the same distance. This relationship is known as the "accommodation-vergence reflex." Similarly, changes in convergence normally cause accommodation. As described herein, many stereoscopic or "3D" display systems display a scene with a slightly different view (and thus a slightly different image) to each eye, allowing the human visual system to perceive three-dimensional depth. However, such systems are not comfortable for many viewers, especially since they only provide different views of the scene to the eyes, and all the image information is at a single focal distance, working against the "accommodation-vergence reflex." A display system that better matches accommodation and vergence would allow for a more realistic and comfortable simulation of three-dimensional images.

[0099] FIG. 4 illustrates an embodiment of a simulation of a three-dimensional image using multiple depth planes. Referring to FIG. 4, the eyes 4, 6 accommodate to focus on objects at various distances from the eyes 4, 6 on the Z axis. The eyes (4 and 6) assume a particular state of accommodation to focus on objects at different distances on the Z axis. As a result, a particular state of accommodation is said to be associated with a particular one of the depth planes 14 and associated with a particular focal length, such that an object or part of an object at a particular depth plane is in focus when the eyes are accommodating to that depth plane. In one embodiment, a three-dimensional image can be simulated by providing a display of a different image to each eye 4, 6 and by providing a display of a different image corresponding to each depth plane. Although shown separated for clarity of explanation, it will be understood that the fields of view of the eyes 4, 6 may overlap as the distance on the Z axis increases. Additionally, although shown as flat for simplicity of description, it will be understood that the shape of the depth plane may be curved in physical space such that the eye is in focus on all features on the depth plane when in a particular state of accommodation.

[0100] Depending on the distance between the object and the eye 4 or 6, the divergence angle of the light from the object as seen by the eye also varies. Figures 5A-5C are diagrams showing the relationship between distance and the divergence angle of the light beam. The distances between the object and the eye 4 are denoted by R1, R2, and R3 in descending order. As shown in Figures 5A-5C, as the distance to the object decreases, the light beam spreads more widely. As the distance increases, the light beam approaches parallelism. In other words, the light field formed by a point (an object or a part of an object) has a spherical wavefront curvature that is a function of how far the point is from the user's eye. The curvature increases as the distance between the object and the eye 4 decreases. As a result, the divergence angle of the light beam is different at different depth planes, and the divergence angle increases as the distance between the depth plane and the viewer's eye 4 decreases. Although only one eye 4 is shown in Figures 5A-5C and other figures of this application for clarity of the drawings, it will be understood that the description of the eye 4 is applicable to both eyes 4 and 6 of the viewer.

[0101] Without wishing to be bound by theory, it is believed that there is a limit to the number of depth planes that the human eye can interpret for depth perception. As a result, by presenting the eye with different representations of an image that correspond to this finite number of depth planes, a highly realistic simulation of depth perception is possible. The viewer's eyes focus on the different representations separately, and the user can obtain depth cues based on the eye's accommodation required to focus on different image features on a scene located at different depth planes and / or by viewing different image features that are out of focus on different depth planes.

[0102] FIG 6 illustrates an example of a waveguide group for outputting image information to a user. Display system 1000 includes a waveguide collection, or collection of waveguide groups, 178, that is used to provide a three-dimensional perception to the eye / brain using multiple waveguides 182, 184, 186, 188, 190. In one embodiment, display system 1000 is system 80 of FIG 2, and FIG 6 is a detailed schematic representation of a portion of system 80. For example, waveguide group 178 may be a corresponding portion of display 62 of FIG 2.

[0103] Continuing with reference to FIG. 6, the group of waveguides 178 may include a number of features 198, 196, 194, 192 between the waveguides. In some embodiments, the features 198, 196, 194, 192 may be lenses. The waveguides 182, 184, 186, 188, 190 and / or the number of lenses 198, 196, 194, 192 may be configured to deliver image information to the eye at various levels of wavefront curvature or divergence angles of the light beam. Each waveguide level may be associated with a depth plane and configured to output image information corresponding to that depth plane. The image injectors 200, 202, 204, 206, 208 may act as light sources for the waveguides and may be used to inject image information into the waveguides 182, 184, 186, 187, 190, which are configured to distribute incoming light to the respective waveguides for output to the eye 4, as described herein. Light exits output faces 300, 302, 304, 306, 308 of image injectors 200, 202, 204, 206, 208 and is injected into corresponding input faces 382, ​​384, 386, 388, 390 of waveguides 182, 184, 186, 188, 190. In some embodiments, input faces 382, ​​384, 386, 388, 390 may be ends of the corresponding waveguides or may be part of the main surface of the corresponding waveguide (i.e., one of the faces of the waveguide that faces the outside world 144 or the viewer's eye 4 directly). In some embodiments, a single beam of light (e.g., a collimated beam) is injected into each waveguide and a full area of ​​replicated collimated beams are output toward eye 4 at a predetermined angle (and divergence angle) corresponding to the depth plane associated with each waveguide. In one embodiment, one of the image injectors 200, 202, 204, 206, 208 may be associated with multiple (eg, three) waveguides 182, 184, 186, 188, 190 to inject light therein.

[0104] In some embodiments, the image injectors 200, 202, 204, 206, 208 are separate displays, each producing image information that is injected into a corresponding waveguide 182, 184, 186, 188, 190. In other embodiments, the image injectors 200, 202, 204, 206, 208 may be outputs of a single multiplexed display, with the image information being coupled to each image injector 200, 202, 204, 206, 208 via one or more optical conduits (e.g., fiber optic cables). It will be appreciated that the image information provided by the image injectors 200, 202, 204, 206, 208 may include light of different wavelengths or colors (e.g., different light components as described herein).

[0105] The controller 210 controls the operation of the waveguide collection 178 and the image injectors 200, 202, 204, 206, 208. In one embodiment, the controller 210 is part of the local processing data module 70. The controller 210 includes programming (e.g., instructions in a non-volatile medium) that coordinates the timing and delivery of image information to the waveguides 182, 184, 186, 188, 190, for example, according to various concepts described herein. In one embodiment, the controller may be a single device or a distributed system connected by wired or wireless communication channels. The controller 210 may be part of the processing module 70 or 72 (FIG. 1) in one embodiment.

[0106] 6, the waveguides 182, 184, 186, 188, 190 may be configured such that light propagates within each waveguide by total internal reflection (TIR). Each of the waveguides 182, 184, 186, 188, 190 may be planar or of other (e.g., curved) shape with upper and lower major surfaces and ends extending between the upper and lower major surfaces. In the illustrated configuration, each of the waveguides 182, 184, 186, 188, 190 may include one or more output coupling optical elements 282, 284, 286, 288, 290 configured to redirect and output coupling light propagating within the respective waveguide out of the waveguide to output image information to the eye 4. The extracted light may also be referred to as output coupled light, and the one or more output coupling optical elements may also be referred to as light extraction optical elements. The extracted light beam is output from the waveguide at a location where the light propagating within the waveguide impinges on the light extraction optical element. Some or all of the one or more output coupling optical elements 282, 284, 286, 288, 290 may be one or more gratings, for example, including diffractive optical features as described in more detail herein. Although shown disposed on the lower major surface of the waveguides 182, 184, 186, 188, 190 for ease of explanation and clarity of illustration, the one or more output coupling optical elements 282, 284, 286, 288, 290 may be disposed on the upper and / or lower major surfaces and / or may be configured directly inside the waveguides 182, 184, 186, 188, 190, as described in more detail herein. In some embodiments, the one or more output coupling optical elements 282, 284, 286, 288, 290 may be formed in a layer of material affixed to a transparent substrate that constitutes the waveguides 182, 184, 186, 188, 190. In other embodiments, the waveguides 182, 184, 186, 188, 190 may be a monolithic piece of material, and the one or more output coupling optical elements 282, 284, 286, 288, 290 may be formed on and / or within such piece of material.

[0107] Continuing to refer to FIG. 6, as described herein, each of the waveguides 182, 184, 186, 188, 190 is configured to output light and form an image corresponding to a respective depth plane. For example, the waveguide 182 closest to the eye may be configured to send collimated light as injected into the waveguide 182 to the eye 4. The collimated light represents optical infinity depth. The next upper waveguide 184 is configured to send collimated light, which passes through a first lens 192 (e.g., a negative lens) before reaching the eye 4. The first lens 192 is configured to provide a weak convex wavefront curvature such that the eye / brain interprets the light originating from this next waveguide 184 as originating from a first depth plane closer to the eye 4 than infinity. Similarly, the output light of the third upper waveguide 186 passes through a first lens 192 and a second lens 194 before reaching the eye 4. The combined refractive power of the first lens 192 and the second lens 194 is configured to further increase the wavefront curvature, so that the eye / brain interprets the light originating from the third waveguide 186 as originating from a second depth plane that is closer to the person from infinity than the light originating from the next waveguide 184. Other methods of producing these perceived colors are possible.

[0108] The other waveguide layers 188, 190 and lenses 196, 198 are similarly configured, with the output of the top waveguide 190 in the collection passing through all lenses between them and the eye, representing the depth plane closest to the person due to their total refractive power. To correct the lenses 198, 196, 194, 192 when viewing / interpreting light coming from the outside world 144 on the other side of the waveguide collection 178, a corrective lens layer 180 may be placed on top of the collection to correct the total refractive index of the following lenses 198, 196, 194, 192. In this configuration, as many depth plane perceptions as there are waveguide-lens pairs can be provided. One or more of the output coupling optics of the waveguides and the focusing of the lenses may be static (i.e., no dynamic or electroactive). In some other embodiments, either or both may be dynamic features using electroactive functions.

[0109] In some embodiments, two or more of the waveguides 182, 184, 186, 188, 190 may be associated with the same depth plane. For example, multiple waveguides 182, 184, 186, 188, 190 may be configured to output images at the same depth plane, and multiple components of the waveguides 182, 184, 186, 188, 190 may be configured to output images at the same depth planes, one set for each depth plane. This may have the effect of forming tiled images that provide an extended field of view at those depth planes.

[0110] 6, one or more output coupling optical elements 282, 284, 286, 288, 290 may be configured to redirect light out of a corresponding waveguide and output couple the light at an appropriate divergence angle corresponding to the respective depth plane associated with that waveguide, or parallel. As a result, waveguides associated with different depth planes are combined with one or more output coupling optical elements 282, 284, 286, 288, 290 that output couple light at different divergence angles depending on the associated depth plane. In some embodiments, features 198, 196, 194, 192 may not be lenses, but simply spacers (e.g., cladding layers and / or structures for creating air gaps).

[0111] In one embodiment, one or more of the output coupling optical elements 282, 284, 286, 288, 290 are diffractive features, or "diffractive optical elements" (also referred to herein as "DOEs"), that form a diffraction pattern. The DOEs preferably have a sufficiently low diffraction efficiency such that only a portion of the light beam is redirected towards eye 4 each time it crosses the DOE, while the remainder continues to travel within the waveguide by total internal reflection. The light with superimposed image information is thus split into several output beams that exit the waveguide at multiple locations, so that certain collimated light that bounces around within the waveguide is output radiated towards eye 4 in a fairly uniform pattern.

[0112] In some embodiments, one or more DOEs may be switchable between an actively diffracting "on" state and a less diffracting "off" state. For example, a switchable DOE may have a layer of polymer dispersed liquid crystal in which microdroplets form a diffractive pattern within a host medium, the microdroplets being switchable to have substantially the same refractive index as the host medium (so that the pattern does not appreciably diffract incident light) and the microdroplets being switchable to have a different refractive index than the host medium (so that the pattern actively diffracts incident light).

[0113] FIG. 7 illustrates an example of an exit beam output from a waveguide. Although one waveguide is illustrated, it will be understood that the group of waveguides 178 includes multiple waveguides, and other waveguides in the group of waveguides 178 may function similarly. Light 400 is injected into the waveguide 182 at its input end 382 and propagates within the waveguide 182 by total internal reflection. At the point where the light impinges on the DOE 282, a portion of the light is output from the waveguide as output beam 402. Although output beam 402 is illustrated as being substantially parallel, it may be directed to propagate at an angle to the eye (e.g., forming a diverging output beam) depending on the depth plane associated with the waveguide 182, as described herein. It will be understood that a substantially parallel output beam may indicate that the waveguide includes one or more output coupling optical elements that output couple light to form an image to be displayed at a depth plane that is a large distance from the eye 4 (e.g., at infinity). Other waveguides or other output coupling optics may output a more spread out output beam pattern that the eye 4 must adjust to a closer distance to focus on the retina, and that is interpreted by the brain as light from a distance closer than infinity.

[0114] FIG. 8 is a schematic diagram of an image formed using multiple different color components at each depth plane of the waveguide collection. In an embodiment, images of each color component, for example, three or more color components, may be superimposed to form a full color image at each depth plane. In an embodiment, depth planes 14a-14f are illustrated, but more or less depths are contemplated. Each depth plane may have three color component images associated therewith, i.e., a first image of a first color G, an image of a second color R, and an image of a third color G. The different depth planes are indicated by different diopter numbers after the letters G, R, and B. For example, the number after each letter indicates the diopter (1 / m) or distance of the depth plane from the viewer, and each box in the diagram indicates a separate color component.

[0115] In some embodiments, light for each color component is output from a dedicated waveguide, resulting in multiple waveguides associated with each depth plane. In such embodiments, each box in the diagram containing the letters G, R, and B represents a separate waveguide, and the three waveguides can be considered to correspond to one depth plane, with three color component images provided per depth plane. For simplicity, the schematic diagram shows the waveguides associated with each depth plane adjacent to each other, but it will be understood that in an actual device, the waveguides may be stacked, one waveguide per level. In other embodiments, multiple color components are output from the same waveguide, for example, one waveguide per depth plane.

[0116] 8, in one embodiment, G is green, R is red, and B is blue. In other embodiments, other colors, including magenta and cyan, may be used in addition to or in place of one or more of red, green, and blue.

[0117] As used herein, reference to light of a certain color will be understood to include light of one or more wavelengths within the range of wavelengths of light perceived by a viewer to be of that color. For example, red light may include one or more wavelengths of light within the range of about 620-780 nm, green light may include one or more wavelengths of light within the range of about 492-577 nm, and blue light may include one or more wavelengths of light within the range of about 435-493 nm.

[0118] 9A, a schematic diagram is provided illustrating an example of a top view of a display device 900 including a waveguide 905, an input coupling optical element 907, and one or more output coupling optical elements 909a / 909b. The waveguide 905 may be planar and have a first major surface 905a, a second major surface 905b opposite the first major surface 905a, and ends extending between the first and second major surfaces 905a and 905b. In such an embodiment, the first and second major surfaces 905a and 905b extend in the xy plane, with a surface normal intersecting the first and second major surfaces 905a and 905b oriented along the z-axis. The waveguide 905 may comprise an optical grade material configured to transmit wavelengths in the visible spectrum or wavelengths corresponding to color components to be output from the waveguide 905. In various embodiments, the waveguides described herein, including the waveguide 905, can be a monolithic piece of material. For example, the first and second major surfaces 905a and 905b and the space between the two major surfaces 905a and 905b can be the same material. In some embodiments, the waveguide can include multiple layers of material. For example, the space between the first and second major surfaces 905a and 905b can include a material with a first refractive index, and the space between the first and second major surfaces 905a and 905b can include a material with a different refractive index.

[0119] The one or more output coupling optical elements may include a first output coupling optical element 909a and a second output coupling optical element 909b as illustrated in Figure 9B, which is a schematic diagram illustrating an example of an A-A' cross section of a display device 900. In some embodiments, the first and second output coupling optical elements 909a and 909b may be combined and formed as a single output coupling optical element, for example on the same major surface or on the first and second major surfaces 905a and 905b.

[0120] The input coupling optical element 907 is configured to couple incident light at a first plurality of wavelengths to propagate through the waveguide 905 in a first direction by total internal reflection and to couple incident light at one or more second wavelengths to propagate through the waveguide in a second direction by total internal reflection. The first and second directions extend coplanar with the first and second major surfaces 905a and 905b of the waveguide 905. For example, as shown in FIG. 9A, when the waveguide 905 is viewed in a direction parallel to the surface normal of the first and second major surfaces 905a and 905b (e.g., when viewed from above when the first major surface 905a of the waveguide 905 faces upward), the first direction may be parallel to the y-axis and the second direction may be parallel to the x-axis. As a result, FIG. 9A shows that the first and second directions are orthogonal to each other coplanar with the first and second major surfaces 905a and 905b. However, in other embodiments, the angle between the first and second directions may be different from 90 degrees when viewed parallel to the surface normal of the first and second major faces 905a and 905b. For example, the angle between the first and second directions may be between 60 and 120 degrees, between 70 and 110 degrees, between 80 and 100 degrees, between 85 and 95 degrees, or any angle therebetween. Preferably, the angle is selected such that light propagating in the first direction is refracted with high efficiency to one output coupling element and with low efficiency to the other output coupling optical element, and light propagating in the second direction is refracted with high efficiency to the former output coupling element and with low efficiency to the latter output coupling optical element.

[0121] The one or more second wavelengths may be different from the first plurality of wavelengths. In various embodiments, light having multiple color components (e.g., red, green, blue) is introduced into the waveguide. The first output coupling optical element 909a is configured to redirect the light of the first plurality of wavelengths propagating in the waveguide 905 along a first direction out of the waveguide 905, and the second output coupling optical element 909b is configured to redirect the light of the one or more second wavelengths propagating in the waveguide 905 along a second direction out of the waveguide 905. In some embodiments, the first plurality of wavelengths includes two color components, e.g., red and blue light, and the one or more second wavelengths includes a third color component, e.g., green light. The two color components are preferably such that the difference in wavelength between these two color components is greater than the difference in wavelength between any of the two color components and the third color component, leading to reduced crosstalk. In one embodiment, the first output coupling optical element 909a includes an ASR to redirect light for each of the two color components.

[0122] It will be appreciated that the waveguide 905 may be part of a collection of waveguides in the display system 1000 (FIG. 6). For example, the waveguide 905 may correspond to one of the waveguides 182, 184, 186, 188, 190, and the output coupling optical elements 909a and 909b may correspond to the output coupling optical elements 282, 284, 286, 288, 290 of FIG.

[0123] 9A and 9B, in various embodiments, the input coupling optical elements 907 may be wavelength selective optical elements configured to redirect light of different wavelengths to propagate along different directions by total internal reflection within the waveguide 905. For example, the input coupling optical elements 907 may comprise a first set of input coupling optical elements configured to act on light of a first plurality of wavelengths and a second set of input coupling optical elements configured to act on light of one or more second wavelengths. In various embodiments, the elements forming the input coupling optical elements 907 may include optical components including one or more optical prisms, or one or more diffractive and / or refractive elements.

[0124] In some embodiments, the input coupling optical element 907 may include one or more gratings acting on one or more wavelengths of light. For example, if the incident light includes red, green, and blue wavelengths of light, the input coupling optical element 907 may include one grating acting on all three wavelengths, with a first grating acting on red light, a second grating acting on green light, and a third grating acting on blue light. In some embodiments, the first grating acting on red light and the third grating acting on blue light may be combined into a single grating structure. The one or more gratings included in the input coupling optical element 907 may include an analog surface relief grating (ASR), a binary surface relief structure (BSR), a volume holographic optical element (VHOE), a digital surface relief structure, and / or a volume phase holographic material (e.g., a hologram recorded in a volume phase holographic material), or a switchable diffractive optical element (e.g., a polymer dispersed liquid crystal (PDLC) grating), etc. Other types of gratings, holograms, and / or diffractive optical elements having the functionality described herein may also be used. The one or more gratings are configured to redirect the incident light of the first plurality of wavelengths, represented by light rays 903i1 and 903i2, such that the light of the first plurality of wavelengths propagates in the waveguide 905 in a first direction (e.g., along a direction parallel to the y-axis) and to redirect the incident light of one or more second wavelengths, represented by light rays 903i3, such that the light of the one or more second wavelengths propagates in a second direction (e.g., along a direction parallel to the x-axis). Thus, the one or more gratings are configured to redirect the light incident from the front of the first main surface 905a or the light incident from the back of the second main surface 905b to an appropriate angle to in-couple the light into the waveguide 905 such that the incident light is totally internally reflected within the waveguide 905. The input coupling optical element 907 may include a diffraction grating and / or a transmission grating. In some embodiments including one or more diffraction gratings, light is projected onto the grating from inside the waveguide 905 and is diffracted along a first or second direction of the waveguide 905 .

[0125] In some embodiments, the one or more wavelength-selective filters 913a and 913b may be integral with or adjacent to the input coupling optical element 907. The one or more wavelength-selective filters 913a and 913b may be configured to filter out a portion of the light at one or more second wavelengths propagating along the first direction and a portion of the light at the first plurality of wavelengths propagating along the second direction, respectively. In some embodiments, the wavelength-selective filters 913a and 913b may be absorptive filters. For example, in various embodiments, the wavelength-selective filters 913a and 913b may be color band absorbers.

[0126] In an embodiment, the wavelength-selective filters 913a and 913b may include dichroic filters. FIG. 9C illustrates an example of a dichroic wavelength-selective filter and the operation of the dichroic wavelength-selective filter. The dichroic wavelength-selective filter 913a (or 913b) is configured to pass or transmit light of a first plurality of wavelengths (or one or more second wavelengths) propagating along a second direction (or a first direction) by total internal reflection and to reflect light of one or more second wavelengths (or the first plurality of wavelengths) propagating along the second direction (or the first direction) by total internal reflection. The light passing through the dichroic wavelength-selective filter 913b (or 913a) is absorbed by an absorber 915b that is integrally formed with or adjacent to the dichroic wavelength-selective filter 913b (or 913a). In this manner, the input coupling optical element 907, alone or in combination with the wavelength selective filter 913b (or 913a) and the absorber 915b, can increase the degree of isolation between the in-coupled light of the first plurality of wavelengths propagating in the waveguide 905 along a first direction and the in-coupled light of one or more second wavelengths propagating in the waveguide 905 along a second direction. In other words, the input coupling optical element 907, alone or in combination with the wavelength selective filter 913b (or 913a) and the absorber 915b, can limit the amount of light of different wavelengths propagating in the waveguide 905 to reduce crosstalk between the in-coupled light of the first plurality of wavelengths propagating in the waveguide 905 along a first direction and the in-coupled light of one or more second wavelengths propagating in the waveguide 905 along a second direction. Reducing crosstalk between the input coupled light of a first plurality of wavelengths propagating within the waveguide 905 along a first direction and the input coupled light of one or more second wavelengths propagating within the waveguide 905 along a second direction may advantageously improve the output coupling efficiency of the first and second output coupling optical elements 909a and 909b, and may also improve the quality of the color image produced by the output coupled light.

[0127] The input coupling optical element 907 may be disposed adjacent to the first or second major surface 905a or 905b of the waveguide 905. In various embodiments, the input coupling optical element 907 may be disposed adjacent a corner of the waveguide 905. The input coupling optical element 907 may be a separate component from the waveguide 905. Conversely, the input coupling optical element 907 may be integral with one or both of the first or second major surfaces 905a or 905b of the waveguide 905. In various embodiments, the input coupling optical element 907 and the waveguide 905 may be integrally integrated. In various embodiments, the input coupling optical element 907 may be formed on a portion of the waveguide 905. For example, in embodiments in which the input coupling optical element 907 includes one or more gratings, the one or more gratings may be formed on a portion of the first and / or second major surfaces 905a and / or 905b of the waveguide 905. In various embodiments, the input coupling optical element 907 may be disposed in an optically transmissive material layer disposed adjacent the first and / or second major surfaces 905a and / or 905b of the waveguide 905. In other embodiments, the input coupling optical element 907 may be disposed in a majority of the waveguide 905, as described herein.

[0128] In various embodiments, the display device 900 may include a first light distribution element 911a disposed in an optical path of the in-coupled light of a first plurality of wavelengths propagating in the waveguide 905 along a first direction. The display device 900 may also include a second light distribution element 911b disposed in an optical path of the in-coupled light of one or more second wavelengths propagating in the waveguide 905 along a second direction. The first and second light distribution elements 911a and 911b may be configured to distribute the light of the first plurality of wavelengths and the one or more second wavelengths along the first and second directions, respectively. For example, in various embodiments, the first and second light distribution elements 911a and 911b may be configured to elongate (e.g., expand the light lengthwise) the light of the first plurality of wavelengths and the one or more second wavelengths along the first and second directions, respectively. The first and second light distribution elements 911a and 911b distribute light along the first and second directions, and therefore may advantageously increase the spot size of the first light beam including the first wavelengths of light and the second light beam including one or more second wavelengths of light, and may therefore be referred to as pupil expanders or orthogonal pupil expanders (OPEs). The first and second light distribution elements 911a and 911b may also serve to increase the size of the exit pupil of the display device 900. Increasing the size of the exit pupil is useful when the display device 900 is configured for direct viewing by a user and / or applied for near-eye viewing. Increasing the size of the exit pupil may also be advantageous in terms of eye relaxation when viewing the display device 900.

[0129] The first and second light distribution elements 911a and 911b may include one or more gratings configured to direct light propagating along the first and second directions to the first and second output coupling optical elements 909a and 909b, respectively. The one or more gratings may have, for example, a predetermined size (e.g., groove depth or groove height, shape, spacing, and / or period) and orientation and may be configured to act on a first plurality of wavelengths of light propagating along a first direction or on one or more second wavelengths of light propagating along a second direction. For example, when the first plurality of wavelengths includes red and blue light, the first light distribution element 911a may include one grating configured to act on red and blue light, or a first grating acting on red light and a second grating acting on blue light. Similarly, when the one or more second wavelengths include green light, the second light distribution element 911b may include a grating acting on green light.

[0130] In some embodiments, the first and second light distribution elements 911a and 911b are configured to redirect a portion of the light impinging on the grating for each bounce of the in-coupled light of the first plurality of wavelengths and the one or more second wavelengths as the light propagates through the waveguide by total internal reflection. The first and second light distribution elements 911a and 911b may split the first and second light beams propagating along the first and second directions into associated multiple beams redirected toward the first and second output coupling optical elements 909a and 909b. In various embodiments, the associated multiple beams may be copies of each other. In this manner, the first and second light distribution elements 911a and 911b may be configured to uniformly or substantially uniformly illuminate a large area of ​​the first and second output coupling optical elements 909a and 909b, resulting in a fairly uniform pattern of output radiation from the waveguide 905. Without any loss of generality, the first and second light distribution elements 911a and 911b may be configured to redirect incident light of a single wavelength or multiple wavelengths within a predetermined wavelength range.

[0131] In various embodiments, the one or more gratings included in the first and second light distribution elements 911a and 911b may include an analog surface relief grating (ASR), a binary surface relief structure (BSR), a volume holographic optical element (VHOE), a digital surface relief structure and / or a volume phase holographic material, or a switchable diffractive optical element (e.g., a polymer dispersed liquid crystal (PDLC) grating), etc. Other types of gratings, holograms, and / or diffractive optical elements configured to function as described herein may also be used. The first and second light distribution elements 911a and 911b may be disposed adjacent to the first or second major surface 905a or 905b of the waveguide 905. In various embodiments, the first and second light distribution elements 911a and 911b may be spaced apart from the first and second output coupling optical elements 909a and 909b, although in some embodiments the first and second light distribution elements 911a and 911b may not be so configured. The first and second light distribution elements 911a and 911b may be integrally configured with one or both of the first or second major surfaces 905a or 905b of the waveguide 905. In various embodiments, the first and second light distribution elements 911a and 911b and the waveguide 905 may be integrally integrated. In various embodiments, the first and second light distribution elements 911a and 911b may be formed on the first and / or second major surfaces 905a and / or 905b of the waveguide 905. In various implementations, the first and second light distribution elements 911a and 911b may be disposed on one or more optically transmissive material layers disposed adjacent the first and / or second major surfaces 905a and / or 905b of the waveguide 905. In other embodiments, the first and second light distribution elements 911a and 911b may be disposed on a majority of the waveguide 905, as described herein.

[0132] As described above, the first and second output coupling optical elements 909a and 909b are configured to direct the light that is coupled into them out of the plane of the waveguide 905. The first and second output coupling optical elements 909a and 909b are configured to direct the light that is input to the first and second output coupling optical elements 909a and 909b to a viewer (e.g., eye 4 in FIG. 7) and change the different wavelengths of light to a suitable angle that is properly superimposed so that the viewer can perceive a color image with good image quality. The first and second output coupling optical elements 909a and 909b may have a refractive power that imparts an opening angle to the light exiting the waveguide 905 so that the image formed by the light exiting the waveguide 905 appears to originate from a predetermined distance. The waveguide 905 can thus be considered to have an associated depth surface that correlates with the refractive power of the first and second output coupling optical elements 909a and 909b. As described herein, various implementations of the display device may include multiple different stacked waveguides similar to the above-described waveguide 905, including the input coupling optical element 907 and the first and second output coupling optical elements 909a and 909b having different refractive powers. In such implementations, the different waveguides may be associated with different depth planes corresponding to the first and second output coupling optical elements 909a and 909b of different refractive powers included therein. Display devices including multiple different stacked waveguides in this manner may be useful for generating 3D images, particularly light field-based 3D images.

[0133] As described above, the first output coupling optical element 909a and the second output coupling optical element 909b may include one or more gratings. For example, the first output coupling optical element 909a may include one or more gratings configured to act on the first plurality of wavelengths of light, and the second output coupling optical element 909b may include one or more gratings configured to act on the one or more second wavelengths of light. For example, when the first plurality of wavelengths includes red and blue wavelengths, the first output coupling optical element 909a may include one grating that acts on red and blue light, or a first grating that acts on red light and a second grating that acts on blue light. In other embodiments, when the one or more second wavelengths includes green light, the second output coupling optical element 909b may include a grating that acts on green light.

[0134] The first and second output coupling optical elements 909a and 909b may include linear grooves, which may be configured to not redirect light propagating along a direction substantially parallel to the length of the grooves enough to exit the waveguide. Conversely, light propagating along a direction at an angle to the grooves (e.g., perpendicular to the length of the grooves) is redirected upon impingement by the grooves to an angle that does not satisfy the requirement for total internal reflection and is output coupled out of the waveguide 905. Thus, the grooves of the first output coupling optical element 909a are oriented in a direction parallel or substantially parallel to the second direction such that light of one or more second wavelengths propagating along the second direction is not redirected by the first output coupling optical element 909a to be output coupled out of the waveguide 905, and such that light of a first plurality of wavelengths propagating along the first direction is redirected by the first output coupling optical element 909a to be output coupled out of the waveguide 905. The grooves of the second output coupling optical element 909b are oriented in a direction parallel or substantially parallel to the first direction so that light of a first plurality of wavelengths propagating along the first direction is not redirected by the second output coupling optical element 909b and output coupled out of the waveguide 905, and so that light of one or more second wavelengths propagating along the second direction is redirected by the second output coupling optical element 909b and output coupled out of the waveguide 905.

[0135] The first and second output coupling optical elements 909a and 909b may include analog surface relief gratings (ASR), binary surface relief structures (BSR), volume holographic optical elements (VHOE), digital surface relief structures and / or volume phase holographic materials (e.g., holograms recorded in volume phase holographic materials), or switchable diffractive optical elements (e.g., polymer dispersed liquid crystal (PDLC) gratings), etc. Other types of gratings, holograms, and / or diffractive optical elements configured to have the functionality described herein may also be used. In various embodiments, the first and second output coupling optical elements 909a and 909b may be configured together as a single output coupling optical element 909. For example, instead of two output coupling optical elements 909a and 909b disposed on the first and second major surfaces 905a and 905b as shown in FIG. 9B, a single output coupling optical element 909 containing different holograms for different wavelengths (e.g., red, green, blue) recorded in a superimposed manner may be disposed on one of the major surfaces 905a and 905b. In some embodiments, a first output coupling optical element 909a is disposed on the first or second major surface 905a or 905b, and a second output coupling optical element 909b is disposed on the other major surface. The first and second output coupling optical elements 909a and 909b may be formed on one or both of the first and second output coupling optical elements 909a and 909b. In various embodiments, the first and second output coupling optical elements may be formed on a layer disposed on one of the first or second major surfaces 905a or 905b.

[0136] FIG. 10A is a schematic diagram illustrating an example of a top view of a display device 1000 including a waveguide 905, an input coupling optical element 1007, wavelength selective filters 1013a and 1013b, and first and second output coupling optical elements 1009a and 1009b. FIGS. 10B and 10C are diagrams illustrating an example of a cross section A-A' of the display device 1000 shown in FIG. 10A. The display device is configured such that incident light of different wavelengths, shown as light rays 903i1, 903i2, and 903i3, is coupled into the waveguide 905 by the input coupling optical element 1007. The input coupling optical element 1007 may be configured to couple all wavelengths of incident light into the waveguide 905 at an appropriate angle to support propagation by total internal reflection within the waveguide. In various embodiments, the input coupling optical element 1007 may not be configured to couple incident light of different wavelengths to propagate along different directions. Thus, in some embodiments, all wavelengths of incident light are coupled into the waveguide and propagate along the same direction within the waveguide. The input coupling optics may include an analog surface relief grating (ASR), a binary surface relief structure (BSR), a volume holographic optical element (VHOE), a digital surface relief structure and / or a volume phase holographic material (e.g., a hologram recorded in a volume phase holographic material), or a switchable diffractive optical element (e.g., a polymer dispersed liquid crystal (PDLC) grating), etc. Other types of gratings, holograms, and / or diffractive optical elements configured to have the functionality described herein may also be used. In various embodiments, the input coupling optics 1007 may include one or more optical prisms, or optical components including one or more diffractive and / or refractive elements.

[0137] The display device 1000 includes wavelength-selective filters 1013a and 1013b, each of which is associated with one of the output coupling optical elements 1009a and 1009b. In the illustrated embodiment, the wavelength-selective filter 1013a is associated with the output coupling optical element 1009a, and the wavelength-selective filter 1013b is associated with the output coupling optical element 1009b. The wavelength-selective filter 1013a includes a first rear surface and a first front surface opposite the first rear surface. The wavelength-selective filter 1013b includes a second rear surface and a second front surface opposite the second rear surface. In an embodiment, the wavelength-selective filter 1013a is disposed in a recess on the first major surface of the waveguide 905, with the first front surface being flush with a portion of the first major surface 905a of the waveguide 905, as shown, for example, in FIG. 10B. In another embodiment, the wavelength-selective filter 1013a is arranged so that the first rear surface is placed (not recessed) on the first major surface 905a, as shown in FIG. 10C. In one embodiment, the wavelength-selective filter 1013b is arranged in a recess on the second major surface of the waveguide 905, with the second front surface being flush with the second major surface 905b of the waveguide 905, as shown, for example, in FIG. 10B. In another embodiment, the wavelength-selective filter 1013b is arranged so that the second rear surface is placed (not recessed) on the second major surface 905b, as shown in FIG. 10C. Light propagating in the waveguide 905 is incident on the first or second rear surface of the first or second wavelength-selective filter 1013a or 1013b, respectively. Light of the first plurality of wavelengths (or one or more second wavelengths) is transmitted through a first rear surface (or a second rear surface) of the first wavelength-selective filter 1013a (or the second wavelength-selective filter 1013b). The first and second wavelength-selective filters 1013a and 1013b can reflect a portion of the light transmitted through the first or second rear surface.

[0138] The wavelength-selective filter 1013a is configured to transmit a portion of the light of the first plurality of wavelengths (e.g., light in the red and blue wavelength ranges) propagating in the waveguide 905 by multiple reflection to a corresponding output coupling optical element 1009a that redirects the light of the first plurality of wavelengths out of the waveguide 905. The wavelength-selective filter 1013a is configured to reflect light of wavelengths different from the first plurality of wavelengths away from the output coupling optical element 1009a. Similarly, the wavelength-selective filter 1013b is configured to transmit a portion of the light of one or more second wavelengths (e.g., light in the green wavelength range) propagating in the waveguide 905 by multiple reflection to a corresponding output coupling optical element 1009b that redirects the light of the one or more second wavelengths out of the waveguide 905. The wavelength-selective filter 1013b is configured to reflect light of wavelengths different from the one or more second wavelengths away from the output coupling optical element 1009b. In this manner, wavelength-selective filters 1013a and 1013b can reduce crosstalk between different wavelengths of light that are coupled out of waveguide 905 to produce a color image.

[0139] In various embodiments, the wavelength-selective filters 1013a and 1013b may include one or more dichroic filters. The wavelength-selective filters 1013a and 1013b may be disposed on the first and second major surfaces 905a and 905b of the waveguide 905. Without any loss of generality, the wavelength-selective filters 1013a and 1013b may be configured to transmit light that is incident approximately perpendicularly to the filters 1013a and 1013b. For example, when the wavelength-selective filters 1013a and 1013b are disposed parallel to the first and second major surfaces 905a and 905b, light that is incident at an angle of, for example, approximately 0 degrees to 20 degrees with respect to the normal of the first and second major surfaces 905a and 905b may be transmitted through the wavelength-selective filters 1013a and 1013b. As a result, wavelength selective filters 1013a and 1013b are configured to transmit light passing through from the surrounding environment, which can be seen by an observer through the waveguide.

[0140] The first and second output coupling optical elements 1009a and 1009b may be disposed on the corresponding wavelength selective filters 1013a and 1013b. For example, the first output coupling optical element 1009a is disposed on the corresponding wavelength selective filter 1013a and configured to output couple light of a first plurality of wavelengths transmitted through the wavelength selective filter 1013a out of the waveguide 905. Similarly, the second output coupling optical element 1009b is disposed on the corresponding wavelength selective filter 1013b and configured to output couple light of one or more second plurality of wavelengths transmitted through the wavelength selective filter 1013b out of the waveguide 905. In an embodiment, the first plurality of wavelengths includes two color components, e.g., red and blue light, and the one or more second wavelengths includes a third color component, e.g., green light, as described herein. Two color components are preferably arranged such that the difference in wavelength between these two color components is greater than the difference in wavelength between either of the two color components and the third color component, which reduces crosstalk. In one embodiment, the first output coupling optical element 1009a includes one or more ASRs to redirect light for each of the two color components, and the second output coupling optical element 1009b includes an ASR to redirect light for the third color component.

[0141] It will be appreciated that the waveguide 905 may be part of a waveguide collection of the display system 1000 (FIG. 6). For example, the waveguide 905 may correspond to one of the waveguides 182, 184, 186, 188, 190, and the output coupling optics 1009a and 1009b and the wavelength selective filters 1013a and 1013b may correspond to the output coupling optics 282, 284, 286, 288, 290 of FIG.

[0142] The first and second output coupling optical elements 1009a and 1009b may be physically and functionally similar to the first and second output coupling optical elements 909a and 909b shown in Figures 9A and 9B and described above. For example, the first and second output coupling optical elements 1009a and 1009b may include an analog surface relief grating (ASR), a binary surface relief structure (BSR), a volume holographic optical element (VHOE), a digital surface relief structure and / or a volume phase holographic material (e.g., a hologram recorded in a volume phase holographic material), or a switchable diffractive optical element (e.g., a polymer dispersed liquid crystal (PDLC) grating), etc.

[0143] Similar to the first and second out-coupling optical elements 909a and 909b, the first and second out-coupling optical elements 1009a and 1009b are configured to redirect the in-coupled incident light with an appropriate angle and efficiency to properly superimpose light of different wavelengths so that a viewer can perceive a color image of good quality. The first and second out-coupling optical elements 1009a and 1009b may have an optical power that imparts an opening angle to the light exiting the waveguide 905 such that an image formed by the light exiting the waveguide 905 appears to originate from a predetermined distance.

[0144] Light redistribution elements, for example first and second light distribution elements 1011a and 1011b, may be positioned on the optical path along the different wavelengths of light propagating in the waveguide 905. The first and second light distribution elements 1011a and 1011b may be physically and functionally similar to the first and second light distribution elements 911a and 911b described above with reference to Figures 9A and 9B. For example, the first and second light distribution elements 1011a and 1011b may include analog surface relief gratings (ASR), binary surface relief structures (BSR), volume holographic optical elements (VHOE), digital surface relief structures and / or volume phase holographic materials (e.g. holograms recorded in volume phase holographic materials), or switchable diffractive optical elements (e.g. polymer dispersed liquid crystal (PDLC) gratings), etc. The first and second light distribution elements 1011a and 1011b may be configured to act on and redirect a portion of the light propagating in the waveguide 905 towards the first and second output coupling optical elements 1009a and 1009b to expand the beam size in the direction of light propagation. Thus, the first and second light distribution elements 1011a and 1011b may also serve to increase the size of the exit pupil of the display device 1000 including the waveguide 905. In one embodiment, the first and second light distribution elements 1011a and 1011b thus function as orthogonal pupil expanders (OPEs).

[0145] Similar to the first and second light distribution elements 911a and 911b, the first and second light distribution elements 1011a and 1011b may be disposed on one or both of the first and second major surfaces 905a and 905b of the waveguide. In the embodiment shown in Figures 10A and 10B, the first light distribution element 1011a is disposed on the first major surface 905a and the second light distribution element 1011b is disposed on the second major surface 905b. In other embodiments, the first and second light distribution elements 1011a and 1011b may be disposed on the same major surface of the waveguide 905. In various embodiments, the first and second light distribution elements 1011a and 1011b may be combined to form a single light distribution optical element.

[0146] In various embodiments, the first and second light distribution elements 1011a and 1011b are configured to perform wavelength selection, redirecting light of certain wavelengths more efficiently than light of other wavelengths. For example, in various embodiments, the first light redistribution element 1011a may be configured to redirect light of a first plurality of wavelengths toward the first output coupling optical element 1009a, and the second light redistribution element 1011b may be configured to redirect light of one or more second wavelengths toward the first output coupling optical element 1009b. In such an embodiment, the first light distribution element 1011a may be disposed above the first wavelength-selective filter 1013a, and the second light distribution element 1011b may be disposed above the second wavelength-selective filter 1013b. In this manner, the amount of light of one or more second (or first plurality) wavelengths redirected to the first (or second) light distribution element 1011a (or 1011b) may be reduced.

[0147] 9A-10B, the first and second out-coupling optical elements 909a, 909b, 1009a and 1009b may be configured to diffract light symmetrically across one of the first or second major surfaces on which they are disposed, such that light from the waveguide is diffracted equally forward and backward across major surfaces 905a and 905b. Thus, the quality of the color image is not significantly degraded even if some of the colors of the color image are out-coupled from output coupling elements disposed on one major surface of the waveguide and some of the other colors of the color image are generated from light out-coupled from output coupling elements disposed on the other major surface of the waveguide.

[0148] Additionally, various input and output coupling optical elements and light distribution elements may be configured to operate on multiple different wavelengths of light with a combination of different diffractive structures, each configured to operate on a single wavelength, that can be formed on the waveguide using manufacturing methods such as injection compression molding, UV replication or nanoimprinting of the diffractive structures.

[0149] 11A, an example of a cross-sectional side view of a plurality of stacked waveguides, or stacked waveguide set 1200, each configured to output light at a different wavelength or range of wavelengths, is shown. The stacked waveguide set 1200 includes waveguides 1210, 1220, and 1230. Each waveguide includes an associated input coupling optical element, such as an input coupling optical element 1212 disposed on a major surface (e.g., bottom major surface) of the waveguide 1210, an input coupling optical element 1222 disposed on a major surface (e.g., bottom major surface) of the waveguide 1220, and an input coupling optical element 1232 disposed on a major surface (e.g., bottom major surface) of the waveguide 1230. In some embodiments, one or more of the input coupling optical elements 1212, 1222, 1232 may be disposed on a top major surface of the corresponding waveguide 1210, 1220, 1230 (especially when one or more of the input coupling optical elements are transmissive refractive optical elements). The input coupling optical elements 1212, 1222, 1232 are preferably disposed on the bottom major surface of the corresponding waveguide 1210, 1220, 1230 (or on top of the next lower waveguide). In some embodiments, the input coupling optical elements 1212, 1222, 1232 may be disposed within the body of the corresponding waveguide 1210, 1220, 1230. The input coupling optical elements 1212, 1222, 1232 are preferably color filters that include filters that selectively reflect one or more wavelengths of light and transmit other wavelengths. Examples of color filters include dichroic filters as described herein. Although illustrated at the edges or corners of the corresponding waveguides 1210, 1220, 1230, it will be understood that the input coupling optical elements 1212, 1222, 1232 may be disposed in other regions of the corresponding waveguides 1210, 1220, 1230 in some embodiments.

[0150] Each waveguide also includes an associated light distribution element, such as light distribution element 1214 disposed on a major surface (e.g., the top major surface) of waveguide 1210, light distribution element 1224 disposed on a major surface (e.g., the top major surface) of waveguide 1220, and light distribution element 1234 disposed on a major surface (e.g., the top major surface) of waveguide 1230. In some other embodiments, light distribution elements 1214, 1224, 1234 may be disposed on bottom major surfaces of corresponding waveguides 1210, 1220, 1230, respectively. In some other embodiments, the light distribution elements 1214, 1224, 1234 may be disposed on both the top and bottom major surfaces of the corresponding waveguides 1210, 1220, 1230, respectively, and the light distribution elements 1214, 1224, 1234 may be disposed on either the top or bottom major surfaces of different corresponding waveguides 1210, 1220, 1230, respectively.

[0151] The waveguides 1210, 1220, 1230 may be discretely arranged and separated by layers of gas and / or liquid material. For example, as shown, layers 1216a and 1218a may separate the waveguides 1210 and 1220, and layers 1216b and 1218b may separate the waveguides 1220 and 1230. In one embodiment, layers 1216a and 1216b are formed of a material that is index-matched to the material forming one of the immediately adjacent waveguides 1210, 1220, 1230. The index-matching layers 1216a and 1216b facilitate the propagation of light through the thickness of the waveguide set 1200, such that light preferably travels through the waveguides 1210, 1220, and 1230, for example, to the input coupling optical element 1232 with little reflection or loss.

[0152] In one embodiment, layers 1216b and 1218b are formed of a low refractive index material (i.e., a material having a refractive index lower than the material forming one of the immediately adjacent waveguides 1210, 1220, 1230). The refractive index of the material forming layers 1216b, 1218b is preferably 0.05 or more, or 0.1 or more less than the refractive index of the material forming waveguides 1210, 1220, 1230. The low refractive index layers 1216b, 1218b preferably function as cladding layers to promote total internal reflection (TIR) ​​of light within the waveguides 1210, 1220, 1230 (e.g., total internal reflection between the top and bottom major surfaces of each waveguide). In one embodiment, layers 1216b, 1218b are formed of air. Although not shown, it will be understood that the top and bottom surfaces of the waveguide set 1200 may include immediately adjacent cladding layers.

[0153] Similar or identical materials forming waveguides 1210, 1220, 1230 and similar or identical materials forming layers 1216b, 1218b are preferred for ease of manufacturing and other considerations. In some embodiments, the materials forming waveguides 1210, 1220, 1230 may differ between one or more of the waveguides and / or the materials forming layers 1216b, 1218b may differ while still maintaining the refractive index relationships described above.

[0154] 11A , light rays 1240, 1242, 1244 are incident on waveguide set 1200. It will be appreciated that waveguide set 1200 may be part of a waveguide collection of display system 1000 (FIG. 6). For example, waveguides 1210, 1220, 1230 may correspond to three of waveguides 182, 184, 186, 188, 190, and light rays 1240, 1242, 1244 may be injected into waveguides 1210, 1220, 1230 by one or more image injectors 200, 202, 204, 206, 208.

[0155] The light beams 1240, 1242, 1244 preferably have different wavelength ranges corresponding to different attributes, e.g., different colors. The input coupling optics 1212, 1222, 1232 selectively redirect the light beams 1240, 1242, 1244 based on particular characteristics of the light attributes, while transmitting light that does not have such attributes or characteristics. In one embodiment, the light attribute is wavelength, and the input coupling optics 1212, 1222, 1232 selectively redirect one or more particular wavelengths of light, respectively, while transmitting other wavelengths to the input coupling optics associated with the lower waveguide.

[0156] For example, input coupling optical element 1212 selectively redirects (e.g., reflects) light beam 1240 having a first wavelength or wavelength range and transmits light beams 1242 and 1244 having different second and third wavelengths or wavelength ranges, respectively. Transmitted light beam 1242 is then redirected upon impingement on input coupling optical element 1222 configured to selectively redirect (e.g., reflect) light of the second wavelength or wavelength range. Light beam 1244 is transmitted to input coupling optical element 1244 and then redirected upon impingement on input coupling optical element 1232 configured to selectively redirect (e.g., reflect) light of the third wavelength or wavelength range. In one embodiment, input coupling optical elements 1212, 1222, 1232 are reflective color filters, such as dichroic filters.

[0157] 11A, the redirected light rays 1240, 1242, 1244 are redirected to propagate within the corresponding waveguides 1210, 1220, 1230. That is, the input coupling optical elements 1212, 1222, 1232 of each waveguide redirect the light to input couple into the corresponding waveguide 1210, 1220, 1230. The light rays 1240, 1242, 1244 are oriented at angles such that the light rays propagate within the respective waveguides 1210, 1220, 1230 by total internal reflection.

[0158] In some embodiments, an angle changing optical element 1260 may be used to change the angle at which the light rays 1240, 1242, 1244 strike the input coupling optical element 1212, 1222, 1232 such that the light rays 1240, 1242, 1244 strike the input coupling optical element 1212, 1222, 1232 at an angle that results in total internal reflection. For example, in some embodiments, the light rays 1240, 1242, 1244 enter the angle changing optical element 1260 at an angle perpendicular to the waveguide 1210. The angle changing optical element 1260 then changes the propagation direction of the light rays 1240, 1242, 1244 such that they strike the input coupling optical element 1212, 1222, 1232 at an angle less than 90 degrees relative to the surface of the waveguide 1210. In some embodiments, the angle changing optical element 1260 is a grating. In some other embodiments, the angle changing optical element 1260 is a prism.

[0159] Continuing to refer to FIG. 11A, light rays 1240, 1242, 1244 propagate within waveguides 1210, 1220, 1230, respectively, by total internal reflection and impinge on light distribution elements 1214, 1224, 1234 corresponding to the waveguides.

[0160] 11B, an example of a perspective view of the multiple stacked waveguides shown in FIG. 11A is shown. As described above, the in-coupled light rays 1240, 1242, 1244 are redirected by the in-coupling optical elements 1212, 1222, 1232, respectively, and propagate by total internal reflection within the waveguides 1210, 1220, 1230, respectively. The light rays 1240, 1242, 1244 then impinge on the light distribution elements 1214, 1224, 1234, respectively. The light distribution elements 1214, 1224, 1234 redirect the light rays 1240, 1242, 1244 to propagate towards the out-coupling optical elements 1250, 1252, 1254, respectively.

[0161] In some embodiments, the light distribution elements 1214, 1224, 1234 are orthogonal pupil expanders (OPEs). In some embodiments, the OPEs redirect or distribute the light to the output coupling optics 1250, 1252, 1254 and increase the size of the beam or spot of this light as it propagates towards the output coupling optics. In some embodiments, for example when the beam size is already the desired size, the light distribution elements 1214, 1224, 1234 may be omitted and the input coupling optics 1212, 1222, 1232 may redirect the light directly to the output coupling optics 1250, 1252, 1254. For example, referring to FIG. 11A, the light distribution elements 1214, 1224, 1234 may be replaced by the output coupling optics 1250, 1252, 1254, respectively, in some embodiments.

[0162] As described herein, it will be appreciated that the output coupling optics 1250, 1252, 1254 may include diffractive structures such as analog surface relief gratings (ASR), binary surface relief structures (BSR), volume holographic optical elements (VHOE), digital surface relief structures and / or volume phase holographic materials, or switchable diffractive optical elements (e.g., polymer dispersed liquid crystal (PDLC) gratings). It will be appreciated that in an embodiment, the output coupling optics 1250, 1252, 1254 may be three of the output coupling optics 282, 284, 286, 288, 290 of FIG. 6. In an embodiment, the output coupling optics 1250, 1252, 1254 are exit pupils (EP) or exit pupil expanders (EPE) that direct light to the viewer's eye 4 (FIG. 7).

[0163] Thus, referring to Figures 11A and 11B, in one embodiment, a waveguide set 1200 includes separate waveguides 1210, 1220, 1230, light distribution elements (e.g., OPEs) 1214, 1224, 1234, and output coupling optical elements (e.g., EPs) 1250, 1252, 1254 for each color component. The three waveguides 1210, 1220, 1230 may be stacked with air gaps between each other, except where the input coupling optical elements (e.g., color filters) 1212, 1222, 1232 are placed. The color filters reflect the desired color into the appropriate waveguide and transmit the light of the other colors. For example, light is first input coupled into the first waveguide 1210 by an angle changing optical element 1260, such as an input coupling grating or a prism. The light then propagates at an angle that would result in total internal reflection if a relatively low refractive index material (e.g., air) were on the opposite side of the encountered surface, and is almost completely reflected when it strikes input coupling optics (e.g., color filters) 1212, 1222, 1232, such as appropriately designed dichroic filters when the light has the appropriate wavelength. In the illustrated example, as described above, light ray 1240 (e.g., green light) reflects off the first input coupling optics (e.g., color filters) 1212 and continues to reflect by total internal reflection into the waveguide to impinge on the light distribution element (e.g., OPE) 1214 and then the output coupling optics (e.g., EP) 1250. Light rays 1242 and 1244 (e.g., blue and red light) pass through input coupling optics (e.g., color filters) 1212 and then into the waveguide 1220. Light ray 1242 reflects from the next input coupling optic (e.g., color filter) 1222, where it continues to reflect by total internal reflection into the waveguide 1220, then on to a light distribution element (e.g., OPE) 1224 and then to an output coupling optic (e.g., EP) 1252. Finally, light ray 1244 (e.g., red light) travels through input coupling optic (e.g., color filter) 1232 into the waveguide 1230, propagates to a light distribution element (e.g., OPE) and then to an output coupling optic (e.g., EP) 1254, and is finally output coupled to the viewer along with the light from the other waveguides 1210, 1220.

[0164] 12A-12B, examples of side cross sections of a waveguide having an angle-changing optical element 1260 that facilitates coupling light into the waveguide are shown. As described herein, the angle-changing optical element 1260 may include a grating that redirects light rays, for example, by diffraction. In certain other embodiments, the angle-changing optical element 1260 may be a prism that changes the propagation direction or angle of the light rays, for example, by refraction. FIG. 12A shows light of one wavelength range being coupled through the prism 1260, reflected from the input coupling optical element (e.g., color filter) 1212, and propagating by total internal reflection in the first waveguide 1210. FIG. 12B shows light of a second wavelength range being transmitted through the input coupling optical element (e.g., color filter) 1212, reflected from the input coupling optical element (e.g., color filter) 1222, and propagating by total internal reflection in the second waveguide 1220.

[0165] It is known that various waveguides (e.g., 905 in Figs. 9A-10B, 1210, 1220, 1230 in Figs. 11A-11B) can be made from materials with a high refractive index. Fig. 13 is a graph showing the predicted effect of refractive index on the field of view. Fig. 13 shows the results of a simulation of a monochromatic eyepiece similar to one of the waveguides 1210, 1220, 1230 in Figs. 11A-11B used with the display 62. In the simulation, the refractive index of the waveguide is varied from values ​​associated with various resins (at the top) to that of fused silica (at the bottom). It can be seen from the graph that the effective field of view is clearly increased. For this reason, in some embodiments, the various waveguides of the present invention can be made from materials that result in high refractive index waveguides.

[0166] In some embodiments, the various waveguides of the present invention (e.g., 905 in Figures 9A-10B, 1210, 1220, 1230 in Figures 11A-11B) may be formed of glass, polymer, plastic, sapphire, resin, or other materials that are transparent to wavelengths in the visible spectrum. As described herein, a waveguide made of a material with a high refractive index may have a high effective field of view (FoV). For example, increasing the refractive index of the waveguide material from about 1.45 to about 1.75 may increase the effective field of view from about 35 degrees to about 60 degrees. Thus, various embodiments of the present invention may include waveguides made of materials with a refractive index greater than 1.5, between about 1.5 and 1.8, greater than 1.6, or greater than 1.8.

[0167] It will be appreciated that in some embodiments, a waveguide having a diffractive structure (e.g., a grating) thereon can be constructed on a high refractive index substrate using manufacturing methods such as, for example, injection compression molding, UV replication, or nanoimprinting of the diffractive structure. In some embodiments, such methods may be used to form ASR structure-based features or binary surface relief features.

[0168] Various example embodiments of the present invention are described herein. Reference to these examples is made in a non-limiting sense. These examples are provided to more broadly illustrate possible modes of carrying out the invention. Various modifications can be made to the described invention, and equivalents can be substituted without departing from the spirit and scope of the invention.

[0169] Although described as glasses in a wearable system as a useful example, the waveguides and related structures and modules of the present invention can be applied to form non-wearable displays. For example, rather than being mounted on a wearable frame 64 (FIG. 2), the display 62 may be mounted on a stand, recessed, or other structure that supports the display 62 and allows the display 62 to provide an image to the viewer 60 without being worn by the viewer 60 (e.g., as a desktop monitor).

[0170] In some embodiments, various features described herein with reference to a given figure may be used in embodiments described with reference to other figures. For example, with reference to Fig. 9B, color filters such as color filters 1013a, 1013b of Figs. 10B and 10C may be provided between output coupling optical elements 909a, 909b and waveguides 905, respectively. Similarly, with reference to Fig. 11A, color filters such as color filters 1013a, 1013b of Figs. 10B and 10C may be provided between output coupling optical elements 1214, 1224, 1234 and corresponding waveguides 1210, 1220, 1230. In each output coupling optical element, the color filter separating the element from the corresponding waveguide is preferably configured to transmit light of the wavelength or wavelengths that the output coupling optical element is configured to output couple and to reflect light of other wavelengths.

[0171] In addition, many modifications may be made to adapt a particular situation, material, composition of matter, method, act, or step to the objective, spirit or scope of the present invention. Moreover, those skilled in the art will recognize that the individual variations described and illustrated herein have independent components and features which can be readily separated or combined with the features of other embodiments without departing from the scope or spirit of the invention. All such modifications are intended to be included within the scope of the appended claims.

[0172] The present invention includes methods performed with subject equipment, including methods of providing suitable equipment in this manner. The act of providing may be performed by an end user. In other words, the act of "providing" may simply be the user obtaining, accessing, proximate to, locating, setting up, enabling, powering on, or otherwise acting upon the requisite equipment in the subject method. The methods described herein may be performed in any order of events that is logically possible in addition to the order of events described.

[0173] Exemplary embodiments of the invention have been described above, along with details regarding material selection and manufacture. Further details of the invention are generally known and understood by those skilled in the art and may be understood in conjunction with the patents and publications cited herein, as well as additional acts commonly or logically applicable to the method-based aspects of the invention.

[0174] In addition, although the invention has been described with reference to several examples having various optional features, the invention is not limited to those described and shown as each of these variations is envisioned. Various modifications to the invention are possible and equivalents (whether described herein or not included for convenience of length) can be substituted without departing from the spirit and scope of the invention. In addition, where numerical ranges are stated, all intermediate values, values ​​between the upper and lower limits of the range, and other intermediate values ​​stated within the range are encompassed by the invention.

[0175] Also, any feature of the described inventive variation may be contemplated as being described and covered alone or in combination with any one or more features described herein. The singular includes the plural of the same. More specifically, the singular forms "a," "an," "said," and "the," as used herein and in the related claims, include the plural unless expressly stated to the contrary. In other words, the plural of "at least one" of the subject matter in this specification and the related claims may be used. Furthermore, claims may be written that exclude optional elements. As such, this statement is intended to serve as precedent for the use of exclusive terms such as "solely," "only," or "negative" limitations in the description of the elements of the claims.

[0176] Without the use of such exclusive terms, the term "comprising" in any claim relating to this specification may permit the addition of elements, regardless of the number of elements recited in the claim, and the addition of features is considered to modify the nature of the elements in the claim. Except as expressly defined herein, all technical and scientific terms used herein shall have the meanings as broadly and commonly understood so long as the claims remain valid.

[0177] The scope of the present invention is not limited to the specification and / or examples described herein, but is defined only by the scope of the language of the claims associated with this specification.

Claims

1. 1. An optical system comprising: a waveguide having a first major surface and a second major surface, the waveguide being configured to propagate light between the first and second major surfaces by total internal reflection; an input coupling optical element configured to couple incident light into the waveguide along a first direction at a first plurality of wavelengths and to couple incident light into the waveguide along a second direction at one or more second wavelengths, when viewed from above the waveguide, wherein the coupled light at the first plurality of wavelengths propagates through the waveguide along the first direction by total internal reflection and the coupled light at the one or more second wavelengths propagates through the waveguide along the second direction by total internal reflection; a first wavelength selective reflector configured to reflect incoupled light of the first plurality of wavelengths propagating along the first direction and pass light of wavelengths other than the first plurality of wavelengths; a second wavelength selective reflector configured to reflect incoupled light of the one or more second wavelengths propagating along the second direction and pass light of wavelengths other than the one or more second wavelengths; a first absorber configured to absorb in-coupled light through the first wavelength selective reflector; a second absorber configured to absorb light incoupled through the second wavelength selective reflector; first and second out-coupling optical elements configured to out-couple the in-coupled light from the waveguide; An optical system comprising:

2. The optical system of claim 1 , wherein the input coupling optical element comprises one or more diffractive optical elements.

3. 3. The optical system of claim 2, wherein each of the one or more diffractive optical elements comprises one of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

4. The optical system of claim 3 , wherein the switchable diffractive optical element is a switchable polymer dispersed liquid crystal (PDLC) grating.

5. The optical system of claim 1 , wherein the first and second wavelength selective reflectors are dichroic filters.

6. The optical system of claim 1 , wherein the first plurality of wavelengths of light includes red light and blue light.

7. The optical system of claim 1 , wherein the one or more second wavelengths of light include green light.

8. a first light distribution element configured to receive in-coupled light of the first plurality of wavelengths traveling along the first direction and distribute light of the first plurality of wavelengths to the first out-coupling optical element; 13. The optical system of claim 1, further comprising: a second light distribution element configured to receive in-coupled light of the one or more second wavelengths traveling along the second direction and distribute light of the one or more second wavelengths to the second output coupling optical element.

9. The optical system of claim 8 , wherein the first and second light distribution elements comprise one or more diffractive optical elements.

10. The optical system of claim 9 , wherein the one or more diffractive optical elements comprise one or more gratings.

11. 9. The optical system of claim 8, wherein the first light distribution element is configured to redirect light of the first plurality of wavelengths to propagate within the waveguide along a direction different from a direction that the second light distribution element is configured to redirect for light of the one or more second wavelengths.

12. 12. The optical system of claim 11 , wherein the first light distribution element is configured to redirect light of the first plurality of wavelengths to propagate within the waveguide along the second direction, and the second light distribution element is configured to redirect light of the one or more second wavelengths to propagate within the waveguide along the first direction.

13. The optical system of claim 8 , wherein the first and second light distribution elements are orthogonal pupil expanders.

14. 2. The optical system of claim 1 , wherein the first output coupling optical element comprises one or more gratings configured to output couple light at the first plurality of wavelengths from the waveguide, and the second output coupling optical element comprises one or more gratings configured to output couple light at the one or more second wavelengths from the waveguide.

15. 15. The optical system of claim 14, wherein the one or more gratings of the first output coupling optical element are disposed on the first major surface of the waveguide and the one or more gratings of the second output coupling optical element are disposed on the second major surface of the waveguide.

16. The optical system of claim 14 , wherein the one or more gratings of the first output coupling optical element and the one or more gratings of the second output coupling optical element are provided on the same major surface of the waveguide.

17. 15. The optical system of claim 14, wherein each of the one or more gratings of the first output coupling optical element comprises one of an analog surface relief grating (ASR), a binary surface relief structure (BSR), a hologram, and a switchable diffractive optical element.

18. The optical system of claim 17 , wherein the switchable diffractive optical element comprises a switchable polymer dispersed liquid crystal (PDLC) grating.

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