Tilting array based display

Abstract

To provide a suitable tilting array based display.SOLUTION: Various embodiments described herein include an optical system for an augmented reality head mounted display eyepiece lens configured to deliver an image to an eye, where the optical system includes optics. The optics is arranged so as to receive light output from a light source. The optics is further arranged relative to a spatial light modulator array such that light received from the light source passes through the optics and illuminates the spatial light modulator array. Light illuminating the spatial light modulator array is redirected back through the optics and coupled into one of a plurality of waveguides through one of a plurality of in-coupling optical elements. At least a portion of the coupled light is emitted from the waveguide by at least one out-coupling optical element and directed to the eye of a user. A viewing optics assembly comprising the spatial light modulator is configured to rotate the spatial light modulator.SELECTED DRAWING: Figure 26A

Description

Technical Field

[0001] (Incorporation by reference to any prior application) This application claims the benefit of priority of U.S. Patent Application No. 62 / 641,976, filed on Mar. 12, 2018, entitled "VERY HIGH INDEX EYEPIECE SUBSTRATE-BASED VIEWING OPTICS ASSEMBLY ARCHITECTURES", which is incorporated herein by reference in its entirety under 35 U.S.C. § 119(e).

[0002] The present disclosure relates to a display system having a common optical system for both spatial light modulator illumination and image projection.

Background Art

[0003] Modern computing and display technologies have facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which a digitally reproduced image or a portion thereof is presented to a user in a manner that appears to be, i.e., can be perceived as, real. A virtual reality, or "VR" scenario typically involves the presentation of digital or virtual image information without transparency to other actual real-world visual inputs, and an augmented reality, i.e., "AR" scenario typically involves the presentation of digital or virtual image information as an augmentation to the visualization of the actual world surrounding the user. A mixed reality, i.e., "MR" scenario is a type of AR scenario that typically involves virtual objects integrated into and responsive to the natural world. For example, an MR scenario may include AR image content that is perceived as being blocked by or otherwise interacting with objects within the real world.

[0004] Referring to FIG. 1, an augmented reality scene 10 is depicted. To the user of AR technology, a real-world park-like setting 20 featuring people, trees, and buildings in the background, and a concrete platform 30 can be seen. The user also "sees" "virtual content" such as a robot image 40 standing on the real-world platform 30 and an avatar character 50 like a flying comic that appears to be an anthropomorphic honeybee. These elements 50, 40 are "virtual" in that they do not exist in the real world. The generation of AR technology, which is complex and promotes a comfortable, natural, and rich presentation of virtual image elements among other virtual or real-world image elements, is difficult for the human visual perception system.

[0005] The systems and methods disclosed herein address various challenges related to AR or VR technology.

[0006] A polarizing beam splitter may be used within a display system to direct polarized light to a light modulator and then direct this light to a viewer or user. There is a continuing need to reduce the size of the display system, and generally, as a result, there is also a need to reduce the size of components of the display system that include components utilizing a polarizing beam splitter. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0007] The various embodiments described herein include an optical system for an extended reality head-mounted display eyepiece configured to deliver an image to an eye, the optical system including an optical train. The optical train is arranged to receive light output from a light source. The optical train is further arranged with respect to a spatial light modulator array such that the light received from the light source passes through the optical train and illuminates the spatial light modulator array. The light illuminating the spatial light modulator array is redirected to return through the optical train and is coupled into one of a plurality of waveguides through one of a plurality of internal coupling optical elements. At least a portion of the coupled light is emitted from the waveguide by at least one external coupling optical element and directed toward the user's eye. The spatial light modulator array is configured to tilt to direct light into an appropriate one of the internal coupling optical elements.

[0008] Various embodiments of a head-mounted display system, such as the examples listed below, having common optics for both spatial light modulator illumination and image projection are described herein.

[0009] Example 1: A head-mounted display system configured to project light onto a user's eyes and display augmented reality image content within the user's field of view, the head-mounted display system comprising: a frame configured to be supported on the user's head; at least one light source configured to output light; a spatial light modulator array arranged to receive light from the at least one light source; an eyepiece lens arranged on the frame, the eyepiece lens being configured to direct light from the spatial light modulator array into the user's eyes and display augmented reality image content in the user's field of view, at least a portion of the eyepiece lens being transparent and being arranged at a location in front of the user's eyes when the user wears the head-mounted display system, the transparent portion transmitting light from a part of the physical environment in front of the user to the user's eyes and providing a view of a part of the physical environment in front of the user; (a) at least one waveguide; (b) at least one internal coupling optical element configured to internally couple light from the spatial light modulator array into the at least one waveguide; (c) at least one external coupling optical element configured to couple light induced within the waveguide out of the waveguide and direct the light towards the user's eyes; an optical system having a refractive power, the optical system being arranged to receive light output from the light source, the light received from the light source passing through the optical system and being arranged with respect to the spatial light modulator array to illuminate the spatial light modulator array; the head-mounted display system being configured such that light illuminating the spatial light modulator array is redirected to return through the optical system and is coupled into the at least one waveguide through the at least one internal coupling optical element, at least a portion of the coupled light being emitted from the at least one waveguide by the at least one external coupling optical element and directed towards the user's eyes; and the spatial light modulator array being configured to tilt so as to direct more light from the at least one light source to different ones of the at least one internal coupling optical element at different times.

[0010] Example 2: The head-mounted display system according to Example 1, comprising first and second waveguides, wherein at least one waveguide has individual first and second internal coupling optical elements associated therewith.

[0011] Example 3: The head-mounted display system according to Example 2, wherein the spatial light modulator array is configured to tilt at a first angle such that when the spatial light modulator array is tilted, more light from the at least one light source is directed to the first internal coupling optical element so that more of the light is coupled into the first waveguide by the first internal coupling optical element than into the second waveguide by the second internal coupling optical element.

[0012] Example 4: The head-mounted display system according to Example 3, wherein the spatial light modulator array is configured to tilt at a second angle such that when the spatial light modulator array is tilted, more light from the at least one light source is directed into the second internal coupling optical element so that more of the light is coupled into the second waveguide by the second internal coupling optical element than into the first waveguide by the first internal coupling optical element.

[0013] Example 5: The head-mounted display system according to any one of Examples 2-4, wherein the first and second waveguides are configured to output light with a wavefront having at least one of different amounts of divergence, convergence, or collimation as if projected from different distances from the user's eye.

[0014] Example 6: The head-mounted display system according to Example 5, wherein the light externally coupled from the first waveguide is collimated and the light output from the second waveguide is divergent.

[0015] Example 7: The first and second waveguides are configured such that light externally coupled from the first waveguide diverges by a first amount and light externally coupled from the second waveguide diverges by a second amount, the second amount being different from the first amount, a head-mounted display system according to Example 5.

[0016] Example 8: The first and second waveguides are configured to output light into different viewing angles so as to provide a generally larger viewing field for the image content presented to the user, a head-mounted display system according to any one of Examples 2-4.

[0017] Example 9: The first and second waveguides have corresponding first and second externally coupled optical elements that are laterally offset from each other so as to provide an increased eyebox for the user to view the image, a head-mounted display system according to any one of Examples 2-4.

[0018] Example 10: The spatial light modulator array comprises a plurality of pixels, a head-mounted display system according to any one of the above Examples.

[0019] Example 11: The plurality of pixels comprises a two-dimensional linear array of pixels including pixels arranged in rows and columns, or a hexagonal closest packing of pixels, a head-mounted display system according to Example 10.

[0020] Example 12: The plurality of pixels comprises at least 1,000 pixels, a head-mounted display system according to Example 10 or Example 11.

[0021] Example 13: Further comprising a rotating stage on which the spatial light modulator array is disposed, the rotating stage having at least one actuator configured to receive a signal and tilt the rotating stage in response to the received signal, a head-mounted display system according to any one of the above Examples.

[0022] Example 14: The head-mounted display system according to any of the above embodiments, wherein the spatial light modulator array is configured to switch between two states, namely, a first state and a second state, and the orientations of the spatial light modulator array are arranged at first and second angles in the first and second states, respectively.

[0023] Example 15: The head-mounted display system according to Example 14, wherein the spatial light modulator array tilts at least 7 degrees when changing from the first state to the second state.

[0024] Example 16: The head-mounted display system according to Example 14, wherein the spatial light modulator array tilts at least 10 degrees when changing from the first state to the second state.

[0025] Example 17: The head-mounted display system according to Example 14, wherein the spatial light modulator array tilts at an angle of 20 degrees or less when changing from the first state to the second state.

[0026] Example 18: The head-mounted display system according to Example 14, wherein the spatial light modulator array tilts at an angle of at least 5 degrees to 15 degrees or less within less than 100 milliseconds when changing from the first state to the second state.

[0027] Example 19: The head-mounted display system according to Example 14, wherein the spatial light modulator array tilts at an angle of at least 10 degrees to 20 degrees or less within less than 100 milliseconds when changing from the first state to the second state.

[0028] Example 20: The head-mounted display system according to any of the above embodiments, wherein the spatial light modulator array includes a reflective spatial light modulator array.

[0029] Example 21: The head-mounted display system according to any of the above embodiments, wherein the spatial light modulator array includes a liquid crystal spatial light modulator array or a movable micromirror array.

[0030] Example 22: The at least one light source includes at least one light emitter and at least one coupling optical system that is arranged with respect to the at least one light emitter and collects the light output therefrom, and the head-mounted display system according to any one of the above examples.

[0031] Example 23: The coupling optical system includes a compound parabolic concentrator (CPC), and the head-mounted display system according to Example 22.

[0032] Example 24: The at least one waveguide includes a stack of waveguides, and the head-mounted display system according to any one of the above examples.

[0033] Example 25: Different waveguides of the stack of waveguides are configured to output light with different individual colors, and the head-mounted display system according to Example 24.

[0034] Example 26: The first, second, and third waveguides of the stack of waveguides are each configured to output light of the first, second, and third colors, respectively, and the light of the first, second, and third colors is light of red, blue, and green colors, respectively, and the head-mounted display system according to Example 24 or Example 25.

[0035] Example 27: The at least one waveguide includes a group of first and second waveguides having individual first and second groups of internal coupling optical elements associated therewith, and the head-mounted display system according to any one of the above examples.

[0036] Example 28: The head-mounted display system according to Example 27, wherein when the spatial light modulator array is tilted at a first angle such that more light from the light source is coupled into one of the waveguides of the first group of waveguides by one of the internal coupling optical elements of the first group of internal coupling optical elements than into one of the waveguides of the second group of waveguides by one of the internal coupling optical elements of the second group of internal coupling optical elements, the spatial light modulator array is configured to tilt so as to direct more light from the at least one light source towards at least one of the internal coupling optical elements of the first group of internal coupling optical elements.

[0037] Example 29: The head-mounted display system according to Example 28, wherein when the spatial light modulator array is tilted at a second angle such that more light from the light source is coupled into the waveguides from the second group of waveguides by one of the internal coupling optical elements of the second group of internal coupling optical elements than into the waveguides from the first group of waveguides by one of the internal coupling optical elements of the first group of internal coupling optical elements, the spatial light modulator array is configured to tilt so as to direct more light from the light source towards the internal coupling optical elements of the second group of internal coupling optical elements.

[0038] Example 30: The head-mounted display system according to Example 27, wherein the at least one light source includes a first light source, the first group of waveguides includes a first waveguide, the first group of internal coupling optical elements includes a first internal coupling optical element configured to couple light from the first light source into the first waveguide of the first group of waveguides, the second group of waveguides includes a first waveguide, and the second group of internal coupling optical elements includes a first internal coupling optical element configured to couple light from the first light source into the first waveguide of the second group of waveguides.

[0039] Example 31: The head-mounted display system according to Example 30, wherein the spatial light modulator array is configured to be tilted at a first angle such that when the spatial light modulator array is tilted at the first angle, more light from the first light source is directed to the first internal coupling optical element of the group of the first internal coupling optical elements than is coupled into the first waveguide of the group of the second waveguides by the first internal coupling optical element of the group of the second internal coupling optical elements.

[0040] Example 32: The head-mounted display system according to Example 31, wherein the spatial light modulator array is configured to be tilted at a second angle such that when the spatial light modulator array is tilted at the second angle, more light from the first light source is directed into the first internal coupling optical element of the group of the second internal coupling optical elements than is coupled into the first waveguide of the group of the first waveguides by the first internal coupling optical element of the group of the first internal coupling optical elements.

[0041] Example 33: The head-mounted display system according to any one of Examples 27 and 30 - 32, wherein the at least one light source includes a second light source, the group of the first waveguides includes a second waveguide, the group of the first internal coupling optical elements includes a second internal coupling optical element configured to couple light from the second light source into the second waveguide of the group of the first waveguides, the group of the second waveguides includes a second waveguide, and the group of the second internal coupling optical elements includes a second internal coupling optical element configured to couple light from the second light source into the second waveguide of the group of the second waveguides.

[0042] Example 34: The head-mounted display system according to Example 33, wherein the spatial light modulator array is configured to be tilted at a first angle such that when the spatial light modulator array is tilted at the first angle, more light from the second light source is directed to the second internal coupling optical element of the first group of internal coupling optical elements than is coupled into the second waveguide of the second group of waveguides by the second internal coupling optical element of the second group of internal coupling optical elements, so that more light from the second light source is coupled into the second waveguide of the first group of waveguides by the second internal coupling optical element of the first group of internal coupling optical elements.

[0043] Example 35: The head-mounted display system according to Example 34, wherein the spatial light modulator array is configured to be tilted at a second angle such that when the spatial light modulator array is tilted at the second angle, more light from the second light source is directed into the second internal coupling optical element of the second group of internal coupling optical elements than is coupled into the second waveguide of the first group of waveguides by the second internal coupling optical element of the first group of internal coupling optical elements, so that more light from the second light source is coupled into the second waveguide of the second group of waveguides by the second internal coupling optical element of the second group of internal coupling optical elements.

[0044] Example 36: The head-mounted display system according to any one of Examples 33-35, wherein the first and second internal coupling optical elements of the first group of internal coupling optical elements are laterally offset from each other.

[0045] Example 37: The head-mounted display system according to Example 36, wherein the first and second internal coupling optical elements of the second group of internal coupling optical elements are laterally offset from each other.

[0046] Example 38: The at least one light source includes a third light source, the group of the first waveguides includes a third waveguide, the group of the first internal coupling optical elements includes a third internal coupling optical element configured to couple light from the third light source into the third waveguide of the group of the first waveguides, the group of the second waveguides includes a third waveguide, and the group of the second internal coupling optical elements includes a third internal coupling optical element configured to couple light from the third light source into the third waveguide of the group of the second waveguides. The head-mounted display system according to any one of Examples 27 and 30-37 includes the third internal coupling optical element.

[0047] Example 39: The spatial light modulator array is configured such that when the spatial light modulator array is tilted at a first angle, more light from the third light source is directed into the third internal coupling optical element of the group of the first internal coupling optical elements so that more of the light from the third light source is coupled into the third waveguide of the group of the first waveguides by the third internal coupling optical element of the group of the first internal coupling optical elements than is coupled into the third waveguide of the group of the second waveguides by the third internal coupling optical element of the group of the second internal coupling optical elements. The head-mounted display system according to Example 38.

[0048] Example 40: The spatial light modulator array is configured such that when the spatial light modulator array is tilted at a second angle, more light from the third light source is directed into the third internal coupling optical element of the group of the second internal coupling optical elements so that more of the light from the third light source is coupled into the third waveguide of the group of the second waveguides by the third internal coupling optical element of the group of the second internal coupling optical elements than is coupled into the third waveguide of the group of the first waveguides by the third internal coupling optical element of the group of the first internal coupling optical elements. The head-mounted display system according to Example 39.

[0049] Example 41: The third internally coupled optical element of the first group of internally coupled optical elements is a head-mounted display system according to any of Examples 38 - 40, which is laterally offset with respect to the first and second internally coupled optical elements of the first group of internally coupled optical elements.

[0050] Example 42: The third internally coupled optical element of the second group of internally coupled optical elements is a head-mounted display system according to Example 41, which is laterally offset with respect to the first and second internally coupled optical elements of the second group of internally coupled optical elements.

[0051] Example 43: The first group of internally coupled optical elements is a head-mounted display system according to any of Examples 27 - 42, which is laterally offset with respect to the second group of internally coupled optical elements.

[0052] Example 44: The first, second, and third light sources each comprise a red, green, and blue light source, respectively, in a head-mounted display system according to any of Examples 38 - 43.

[0053] Example 45: The first and second groups of waveguides are configured to output light with a wavefront having at least one of different amounts of divergence, convergence, and collimation, as if projected from different distances from the user's eye, in a head-mounted display system according to any of Examples 27 - 42.

[0054] Example 46: The first and second groups of waveguides are configured such that the light externally coupled from the first group of waveguides is collimated and the light output from the second group of waveguides diverges, in a head-mounted display system according to Example 45.

[0055] Example 47: A head-mounted display system according to Example 45, wherein a first group of waveguides and a second group of waveguides are configured such that light externally coupled from the first group of waveguides diverges by a first amount and light externally coupled from the second group of waveguides diverges by a second amount, and the second amount is different from the first amount.

[0056] Example 48: A head-mounted display system according to any one of Examples 27-44, wherein a first group of waveguides and a second group of waveguides are configured to output light into different viewing angles so as to provide an overall larger viewing field for image content presented to a user.

[0057] Example 49: A head-mounted display system according to any one of Examples 27-44, having individual external coupling optical elements, wherein a first group of waveguides and a second group of waveguides are laterally offset relative to each other so as to provide an increased eye box for a user to view image content.

[0058] Any of the above examples or additional examples can be combined. In addition, any of the above examples or additional examples can be integrated with a head-mounted display. In addition, any of the above examples or additional examples can be implemented with a single depth plane and / or one or more variable depth planes (e.g., one or more elements with variable focusing power that provide a depth-of-field adjustment cue that varies over time).

[0059] Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will be apparent from the description, drawings, and claims. Neither this summary nor the following detailed description purports to define or limit the scope of the subject matter of the invention. The present invention provides, for example, the following. (Item 1) A head-mounted display system, wherein the head-mounted display system is configured to project light onto a user's eyes and display augmented reality image content within the user's field of view, and the head-mounted display system A frame configured to be supported on the user's head, At least one light source configured to output light, A spatial light modulator array arranged to receive light from the at least one light source, An eyepiece lens disposed on the frame, the eyepiece lens being configured to direct light from the spatial light modulator array into the user's eyes and display augmented reality image content in the user's field of view, at least a part of the eyepiece lens being transparent, and when the user wears the head-mounted display system, the transparent part is disposed at a location in front of the user's eyes, and the transparent part transmits light from a part of the physical environment in front of the user to the user's eyes, providing a view of a part of the physical environment in front of the user, and the eyepiece lens (a) At least one waveguide, (b) At least one internal coupling optical element, the at least one internal coupling optical element being configured to internally couple light from the spatial light modulator array into the at least one waveguide, (c) At least one external coupling optical element, the at least one external coupling optical element being configured to couple light guided within the waveguide out of the waveguide and direct the light towards the user's eyes And an eyepiece lens comprising, An optical system having a refractive power, the optical system being arranged to receive light output from the light source, and the optical system being arranged with respect to the spatial light modulator array such that the light received from the light source passes through the optical system and illuminates the spatial light modulator array, Comprising, In the head-mounted display system, light illuminating the spatial light modulator array is redirected so as to return through the optical system, and is coupled into the at least one waveguide through the at least one internal coupling optical element. At least a part of the coupled light is configured to be emitted from the at least one waveguide by the at least one external coupling optical element and directed towards the user's eyes. The head-mounted display system, wherein the spatial light modulator array is configured to tilt so as to direct more light from the at least one light source to different ones of the at least one internal coupling optical element at different times. (Item 2) The head-mounted display system according to item 1, wherein the at least one waveguide includes first and second waveguides, and the first and second waveguides have respective first and second internal coupling optical elements associated therewith. (Item 3) The head-mounted display system according to item 2, wherein when the spatial light modulator array is tilted at a first angle, the spatial light modulator array is configured to tilt so as to direct more light from the at least one light source to the first internal coupling optical element such that more of the light is coupled into the first waveguide by the first internal coupling optical element than is coupled into the second waveguide by the second internal coupling optical element. (Item 4) The head-mounted display system according to item 3, wherein when the spatial light modulator array is tilted at a second angle, the spatial light modulator array is configured to tilt so as to direct more light from the at least one light source into the second internal coupling optical element such that more of the light is coupled into the second waveguide by the second internal coupling optical element than is coupled into the first waveguide by the first internal coupling optical element. (Item 5) The first and second waveguides of the head-mounted display system according to any one of items 2-4 are configured to output light with a wavefront having at least one of different amounts of divergence, convergence, or collimation, as if projected from different distances from the user's eyes. (Item 6) The first and second waveguides of the head-mounted display system according to item 5 are configured such that light externally coupled from the first waveguide is collimated and light output from the second waveguide diverges. (Item 7) The first and second waveguides of the head-mounted display system according to item 5 are configured such that light externally coupled from the first waveguide diverges by a first amount and light externally coupled from the second waveguide diverges by a second amount, and the second amount is different from the first amount. (Item 8) The first and second waveguides of the head-mounted display system according to any one of items 2-4 are configured to output light into different viewing angles so as to provide a generally larger viewing field for the image content presented to the user. (Item 9) The first and second waveguides have corresponding first and second externally coupled optical elements, and the corresponding first and second externally coupled optical elements are laterally offset from each other so as to provide an increased eyebox for the user to view the image, of the head-mounted display system according to any one of items 2-4. (Item 10) The spatial light modulator array includes a plurality of pixels, of the head-mounted display system according to any of the above items. (Item 11) The plurality of pixels include a two-dimensional linear array of pixels arranged in rows and columns, or a hexagonal closest packing of pixels, of the head-mounted display system according to item 10. (Item 12) The head-mounted display system according to item 10 or item 11, wherein the plurality of pixels includes at least 1,000 pixels. (Item 13) The head-mounted display system according to any of the preceding items, further comprising a rotating stage, wherein the spatial light modulator array is disposed on the rotating stage, and the rotating stage is configured to receive a signal and tilt the rotating stage in response to the received signal, and has at least one actuator. (Item 14) The head-mounted display system according to any of the preceding items, wherein the spatial light modulator array includes a spatial modulator array, the spatial modulator array is configured to switch between two states, i.e., a first state and a second state, and the orientations of the spatial light modulator array are arranged at first and second angles in the first and second states, respectively. (Item 15) The head-mounted display system according to item 14, wherein the spatial light modulator array tilts by at least 7 degrees when changing from the first state to the second state. (Item 16) The head-mounted display system according to item 14, wherein the spatial light modulator array tilts by at least 10 degrees when changing from the first state to the second state. (Item 17) The head-mounted display system according to item 14, wherein the spatial light modulator array tilts at an angle of 20 degrees or less when changing from the first state to the second state. (Item 18) The head-mounted display system according to item 14, wherein the spatial light modulator array tilts at an angle of at least 5 degrees to 15 degrees or less within less than 100 milliseconds when changing from the first state to the second state. (Item 19) The head-mounted display system according to item 14, wherein the spatial light modulator array tilts at an angle of at least 10 degrees to 20 degrees or less within less than 100 milliseconds when changing from the first state to the second state. (Item 20) The spatial light modulator array includes a reflective spatial light modulator array, and the head-mounted display system according to any one of the above items. (Item 21) The spatial light modulator array includes a liquid crystal spatial light modulator array or a movable micromirror array, and the head-mounted display system according to any one of the above items. (Item 22) The at least one light source includes at least one light emitter and at least one coupling optical system that is arranged with respect to the at least one light emitter and collects the light output therefrom, and the head-mounted display system according to any one of the above items. (Item 23) The coupling optical system includes a compound parabolic concentrator (CPC), and the head-mounted display system according to Item 22. (Item 24) The at least one waveguide includes a stack of waveguides, and the head-mounted display system according to any one of the above items. (Item 25) The different waveguides of the stack of waveguides are configured to output light with different individual colors, and the head-mounted display system according to Item 24. (Item 26) The first, second, and third waveguides of the stack of waveguides are each configured to output light of the first, second, and third colors, and the light of the first, second, and third colors is red, blue, and green light, respectively, and the head-mounted display system according to Item 24 or Item 25. (Item 27) The at least one waveguide includes a group of first and second waveguides, and the group of first and second waveguides has individual first and second groups of internal coupling optical elements associated therewith, and the head-mounted display system according to any one of the above items. (Item 28) The spatial light modulator array is configured such that when the spatial light modulator array is tilted at a first angle, more of the light from the light source is directed to at least one of the internal coupling optical elements of the first group of internal coupling optical elements so that it is coupled into one of the waveguides in the first group of waveguides by one of the internal coupling optical elements of the first group of internal coupling optical elements rather than being coupled into one of the waveguides in the second group of waveguides by one of the internal coupling optical elements of the second group of internal coupling optical elements, the head-mounted display system according to item 27. (Item 29) The spatial light modulator array is configured such that when the spatial light modulator array is tilted at a second angle, more of the light from the light source is directed to the internal coupling optical elements of the second group of internal coupling optical elements so that it is coupled into the waveguides from the second group of waveguides by the internal coupling optical elements of the second group of internal coupling optical elements rather than being coupled into the waveguides from the first group of waveguides by the internal coupling optical elements of the first group of internal coupling optical elements, the head-mounted display system according to item 28. (Item 30) The at least one light source includes a first light source, the first group of waveguides includes a first waveguide, the first group of internal coupling optical elements includes a first internal coupling optical element configured to couple the light from the first light source into the first waveguide of the first group of waveguides, the second group of waveguides includes a first waveguide, and the second group of internal coupling optical elements includes a first internal coupling optical element configured to couple the light from the first light source into the first waveguide of the second group of waveguides, the head-mounted display system according to item 27. (Item 31) The head-mounted display system according to item 30, wherein when the spatial light modulator array is tilted at a first angle, the spatial light modulator array is configured to tilt so that more of the light from the first light source is directed to the first internal coupling optical element of the group of the first internal coupling optical elements than is coupled into the first waveguide of the group of the first waveguides by the first internal coupling optical element of the group of the second internal coupling optical elements, so that more of the light from the first light source is coupled into the first waveguide of the group of the first waveguides by the first internal coupling optical element of the group of the first internal coupling optical elements. (Item 32) The head-mounted display system according to item 31, wherein when the spatial light modulator array is tilted at a second angle, the spatial light modulator array is configured to tilt so that more of the light from the first light source is directed into the first internal coupling optical element of the group of the second internal coupling optical elements than is coupled into the first waveguide of the group of the second waveguides by the first internal coupling optical element of the group of the first internal coupling optical elements, so that more of the light from the first light source is coupled into the first waveguide of the group of the second waveguides by the first internal coupling optical element of the group of the second internal coupling optical elements. (Item 33) The head-mounted display system according to any one of items 27 and 30-32, wherein the at least one light source includes a second light source, the group of the first waveguides includes a second waveguide, the group of the first internal coupling optical elements includes a second internal coupling optical element configured to couple the light from the second light source into the second waveguide of the group of the first waveguides, the group of the second waveguides includes a second waveguide, and the group of the second internal coupling optical elements includes a second internal coupling optical element configured to couple the light from the second light source into the second waveguide of the group of the second waveguides. (Item 34) The spatial light modulator array is configured to tilt at a first angle such that when the spatial light modulator array is tilted at the first angle, more of the light from the second light source is directed into the second waveguide of the first group of waveguides by the second internal coupling optical element of the first group of internal coupling optical elements than is coupled into the second waveguide of the second group of waveguides by the second internal coupling optical element of the second group of internal coupling optical elements, and more of the light from the second light source is directed into the second internal coupling optical element of the first group of internal coupling optical elements. The head-mounted display system according to item 33. (Item 35) The spatial light modulator array is configured to tilt at a second angle such that when the spatial light modulator array is tilted at the second angle, more of the light from the second light source is directed into the second internal coupling optical element of the second group of internal coupling optical elements than is coupled into the second waveguide of the first group of waveguides by the second internal coupling optical element of the first group of internal coupling optical elements, and more of the light from the second light source is directed into the second internal coupling optical element of the second group of internal coupling optical elements. The head-mounted display system according to item 34. (Item 36) The first and second internal coupling optical elements of the first group of internal coupling optical elements are laterally offset from each other. The head-mounted display system according to any one of items 33 - 35. (Item 37) The first and second internal coupling optical elements of the second group of internal coupling optical elements are laterally offset from each other. The head-mounted display system according to item 36. (Item 38) The at least one light source includes a third light source, the group of the first waveguides includes a third waveguide, the group of the first internal coupling optical elements includes a third internal coupling optical element configured to couple light from the third light source into the third waveguide of the group of the first waveguides, the group of the second waveguides includes a third waveguide, and the group of the second internal coupling optical elements includes a third internal coupling optical element configured to couple light from the third light source into the third waveguide of the group of the second waveguides. The head-mounted display system according to any one of items 27 and 30-37. (Item 39) The spatial light modulator array is configured to tilt at a first angle such that when the spatial light modulator array is tilted at a first angle, more light from the third light source is directed into the third internal coupling optical element of the group of the first internal coupling optical elements than is coupled into the third waveguide of the group of the second waveguides by the third internal coupling optical element of the group of the second internal coupling optical elements. The head-mounted display system according to item 38. (Item 40) The spatial light modulator array is configured to tilt at a second angle such that when the spatial light modulator array is tilted at a second angle, more light from the third light source is directed into the third internal coupling optical element of the group of the second internal coupling optical elements than is coupled into the third waveguide of the group of the first waveguides by the third internal coupling optical element of the group of the first internal coupling optical elements. The head-mounted display system according to item 39. (Item 41) The third internal coupling optical element of the first group of internal coupling optical elements is laterally offset with respect to the first and second internal coupling optical elements of the first group of internal coupling optical elements, the head-mounted display system according to any one of items 38-40. (Item 42) The third internal coupling optical element of the second group of internal coupling optical elements is laterally offset with respect to the first and second internal coupling optical elements of the second group of internal coupling optical elements, the head-mounted display system according to item 41. (Item 43) The first group of internal coupling optical elements is laterally offset with respect to the second group of internal coupling optical elements, the head-mounted display system according to any one of items 27-42. (Item 44) The first, second, and third light sources each include a red, green, and blue light source, the head-mounted display system according to any one of items 38-43. (Item 45) The first and second groups of optical waveguides are configured to output light with a wavefront having at least one of different amounts of divergence, convergence, and collimation as if projected from different distances from the user's eyes, the head-mounted display system according to any one of items 27-42. (Item 46) The first and second groups of optical waveguides are configured such that the light externally coupled from the first group of optical waveguides is collimated and the light output from the second group of optical waveguides diverges, the head-mounted display system according to item 45. (Item 47) The first and second groups of optical waveguides are configured such that the light externally coupled from the first group of optical waveguides diverges by a first amount and the light externally coupled from the second group of optical waveguides diverges by a second amount, the second amount being different from the first amount, the head-mounted display system according to item 45. (Item 48) The first and second groups of waveguides are configured to output light into different viewing angles so as to provide a generally larger field of view for the image content presented to the user, the head-mounted display system according to any one of items 27-44. (Item 49) The first and second groups of waveguides have individual external coupling optical elements that are laterally offset from each other so as to provide an increased eye box to the user for viewing image content, the head-mounted display system according to any one of items 27-44.

Brief Description of the Drawings

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[0117] Reference is now made to the figures, where like reference numerals refer to like parts throughout. Unless otherwise indicated, the drawings are schematic and are not necessarily drawn to scale.

[0118] FIG. 2 illustrates a conventional display system for simulating a three-dimensional image for a user. It should be understood that when the user's eyes are separated and looking at a real object in space, each eye has a slightly different view of the object and can form an image of the object at different locations on the retina of each eye. This can be referred to as binocular disparity and can be utilized by the human visual system to provide a perception of depth. The conventional display system simulates binocular disparity by presenting two distinct images 190, 200 with slightly different views of one identical virtual object for each of the eyes 210a, 210b, corresponding to the views of the virtual object that would appear to each eye as if the virtual object were a real object at the desired depth. These images provide binocular cues that the user's visual system can interpret to derive a perception of depth.

[0119] Continuing to refer to FIG. 2, images 190, 200 are separated from eyes 210a, 210b by a distance 230 on the z-axis. The z-axis is parallel to the optical axis of the user in a state where the eyes are fixated on an object at the optical infinity immediately in front of the user. Images 190, 200 are flat and at a fixed distance from eyes 210a, 210b. Based on slightly different views of the virtual object in the images presented to eyes 210a, 210b respectively, the eyes can naturally rotate so that the image of the object comes to corresponding points on the respective retinas of the eyes and single binocular vision is maintained. This rotation can converge the respective lines of sight of eyes 210a, 210b onto a point in the space where the virtual object is perceived to exist. As a result, providing a three-dimensional image has conventionally involved providing binocular cues that can manipulate the convergence / divergence movement of eyes 210a, 210b and that the human visual system interprets to provide a perception of depth.

[0120] However, generating a realistic and comfortable perception of depth is difficult. It should be understood that light from objects at different distances from the eyes has wavefronts with different amounts of divergence. FIGS. 3A - 3C illustrate the relationship between distance and the divergence of light rays. The distances between the object and eye 210 are represented in the order of decreasing distances R1, R2, and R3. As shown in FIGS. 3A - 3C, the light rays diverge more as the distance to the object decreases. Conversely, as the distance increases, the light rays become more collimated. In other words, it can be said that the light field generated by a point (object or part of an object) has a spherical wavefront curvature that is a function of the distance the point is away from the user's eyes. As the curvature increases, the distance between the object and eye 210 decreases. Only a single eye 210 is illustrated in FIGS. 3A - 3C and various other figures herein for clarity of illustration, but the discussion regarding eye 210 can be applied to both eyes 210a and 210b of the viewer.

[0121] Continuing to refer to FIGS. 3A-3C, light from an object on which the user's eye is fixated can have different wavefront divergences. Due to the different amounts of wavefront divergence, the light can be focused differently by the eye's lens, which in turn can require the lens to assume different shapes to form a focused image on the retina of the eye. If the focused image is not formed on the retina, the resulting retinal blur acts as a cue for accommodation, causing a change in the shape of the eye's lens until the focused image is formed on the retina. For example, the cue for accommodation induces relaxation or contraction of the ciliary muscle surrounding the eye's lens, thereby modulating the force applied to the zonular fibers that hold the lens, and thus changing the shape of the eye's lens until the retinal blur of the fixated object is eliminated or minimized, thereby forming a focused image of the fixated object on the retina (e.g., fovea) of the eye. The process by which the eye's lens changes shape can be referred to as accommodation, and the shape of the eye's lens required to form a focused image of a fixated object on the retina (e.g., fovea) of the eye can be referred to as the accommodative state.

[0122] Referring now to FIG. 4A, the representation of the accommodation-convergence / divergence movement response of the human visual system is illustrated. The movement of the eyes to fixate on an object causes the eyes to receive light from the object, and the light forms an image on each of the retinas of the eyes. The presence of retinal blur in the images formed on the retinas can provide a cue for accommodation, and the relative location of the images on the retinas can provide a cue for convergence / divergence movement. The cue for accommodation results in accommodation occurring and the eye's lens assuming a particular accommodation state that forms a focused image of the object on the eye's retina (e.g., the fovea). On the other hand, the cue for convergence / divergence movement causes a convergence / divergence movement (rotation of the eyes) such that the images formed on each retina of each eye are at corresponding retinal points that maintain single binocular vision. At these positions, it can be said that the eyes are in a particular convergence / divergence movement state. Continuing to refer to FIG. 4A, accommodation can be understood as the process by which the eyes achieve a particular accommodation state, and convergence / divergence movement can be understood as the process by which the eyes achieve a particular convergence / divergence movement state. As shown in FIG. 4A, the accommodation and convergence / divergence movement states of the eyes can change when the user fixates on another object. For example, the accommodated state can change when the user fixates on a new object at a different depth along the z-axis.

[0123] Without being limited by theory, it is believed that the user of the object may perceive the object as "three-dimensional" due to the combination of convergence / divergence movement and accommodation. As described above, the convergence / divergence movement of the two eyes relative to each other (e.g., the rotation of the eyes such that the pupils move towards or away from each other and converge the line of sight of the eyes to fixate on an object) is closely associated with the accommodation of the eye's lens. Under normal conditions, changing the shape of the eye's lens and changing the focus to another object at a different distance from one object will automatically cause a corresponding change in convergence / divergence movement to the same distance under a relationship known as the "accommodation-convergence / divergence reflex". Similarly, a change in convergence / divergence movement will, under normal conditions, induce a corresponding change in the shape of the lens.

[0124] Referring now to FIG. 4B, examples of different accommodation and convergence / divergence motion states of the eyes are illustrated. The pair of eyes 222a fixates on an object at optical infinity, while the pair of eyes 222b fixates on an object 221 at less than optical infinity. It should be noted that the convergence / divergence motion states of each pair of eyes are different, with the pair of eyes 222a being directed straight, while the pair of eyes 222 converges onto the object 221. The accommodation states of the eyes forming each pair of eyes 222a and 222b are also different, as represented by the different shapes of the crystalline lenses 220a, 220b.

[0125] Unfortunately, many users of conventional "3-D" display systems find such conventional systems uncomfortable or do not perceive any sense of depth at all due to the inconsistency between accommodation and convergence / divergence motion states in these displays. As described above, many stereoscopic or "3-D" display systems display a scene by providing slightly different images to each eye. Such systems are uncomfortable for many users because they merely provide different presentations of the scene, causing a change in the convergence / divergence motion state of the eyes, but without a corresponding change in the accommodation state of those eyes. Rather, the images are presented at a fixed distance from the eyes by the display such that the eyes view all the image information in a single accommodation state. Such an arrangement goes against the "accommodation-convergence / divergence reflex" by causing a change in the convergence / divergence motion state without a corresponding change in the accommodation state. This inconsistency is thought to cause discomfort to the user. A display system that provides better alignment between accommodation and convergence / divergence motion can create a more realistic and comfortable simulation of three-dimensional images.

[0126] Although not limited by theory, the human eye is typically thought to be able to interpret a finite number of depth planes and provide depth perception. As a result, a highly realistic simulation of the perceived depth can be achieved by providing different presentations of images corresponding to each of these limited number of depth planes to the eye. In some embodiments, the different presentations may provide both cues for convergence / divergence motion and matching cues for accommodation, thereby providing physiologically correct accommodation-convergence / divergence motion matching.

[0127] Continuing to refer to FIG. 4B, two depth planes 240 corresponding to different distances in space from eyes 210a, 210b are illustrated. For a given depth plane 240, convergence / divergence motion cues may be provided by appropriately displaying images of different viewpoints for each of eyes 210a, 210b. Additionally, for a given depth plane 240, the light forming the images provided to each eye 210a, 210b may have wavefront divergence corresponding to a light field generated by a point at the distance of that depth plane 240.

[0128] In the illustrated embodiment, the distance along the z-axis of depth plane 240 containing point 221 is 1 m. As used herein, the distance or depth along the z-axis may be measured using a zero point located at the exit pupil of the user's eye. Thus, depth plane 240 located at a depth of 1 m corresponds to a distance of 1 m from the exit pupil of the user's eye on the optical axis of those eyes with the eyes directed towards optical infinity. As an approximation, the depth or distance along the z-axis is measured from the front of the user's eye (e.g., the surface of the waveguide), and a value related to the distance between the device and the exit pupil of the user's eye may be added. That value is referred to as the pupil distance and may correspond to the distance between the exit pupil of the user's eye and the display worn by the user in front of the eye. In practice, the value for the pupil distance may generally be a normalized value used for all users. For example, the pupil distance may be assumed to be 20 mm, and the depth plane at a depth of 1 m may be at a distance of 980 mm in front of the display.

[0129] Referring now to FIGS. 4C and 4D, examples of the consistent vergence-accommodation movement distance and the inconsistent vergence-accommodation movement distance are illustrated, respectively. As illustrated in FIG. 4C, the display system may provide an image of a virtual object to each eye 210a, 210b. The image may cause the eyes 210a, 210b to assume a vergence-accommodation state in which the eyes converge on point 15 on depth plane 240. In addition, the image may be formed by light having a wavefront curvature corresponding to the real object in that depth plane 240. As a result, the eyes 210a, 210b assume a state of accommodation in which the image is in focus on their retinas. Thus, the user may perceive the virtual object as being at point 15 on depth plane 240.

[0130] It should be understood that the focusing and convergence / divergence movement states of eyes 210a and 210b are each associated with a specific distance on the z-axis. For example, an object at a specific distance from eyes 210a and 210b causes those eyes to assume a specific focusing state based on the distance of the object. The distance associated with a specific focusing state may be referred to as the focusing distance Ad. Similarly, there exists a specific convergence / divergence movement distance Vd or relative position to each other associated with the eyes in a specific convergence / divergence movement state. When the focusing distance and the convergence / divergence movement distance are consistent, the relationship between focusing and convergence / divergence movement can be said to be physiologically correct. This is regarded as the most comfortable scenario for the user.

[0131] However, in a stereoscopic display, the focusing distance and the convergence / divergence movement distance may not always be consistent. For example, as illustrated in FIG. 4D, the images displayed to eyes 210a and 210b may be displayed with wavefront divergence corresponding to the depth plane 240, and eyes 210a and 210b may assume a specific focusing state in which points 15a and 15b on that depth plane are in focus. However, the images displayed to eyes 210a and 210b may provide a cue for convergence / divergence movement that converges eyes 210a and 210b on a point 15 that is not located on the depth plane 240. As a result, in some embodiments, the focusing distance corresponds to the distance from the exit pupils of eyes 210a and 210b to the depth plane 240, while the convergence / divergence movement distance corresponds to a greater distance from the exit pupils of eyes 210a and 210b to point 15. The focusing distance is different from the convergence / divergence movement distance. As a result, there exists a focusing-convergence / divergence movement inconsistency. Such an inconsistency is regarded as undesirable and may cause discomfort to the user. It should be understood that the inconsistency corresponds to a distance (e.g., Vd - Ad) and can be characterized using diopters.

[0132] In some embodiments, it should be understood that reference points other than the exit pupils of eyes 210a, 210b may also be utilized to determine a distance for determining a vergence-accommodation mismatch, as long as the same reference point is utilized for the accommodation distance and the vergence / divergence movement distance. For example, the distance can be measured from the cornea to a depth plane, from the retina to a depth plane, from an eyepiece (e.g., a waveguide of a display device) to a depth plane, and so on.

[0133] Although not limited by theory, it is believed that a user may physiologically perceive a vergence-accommodation mismatch of up to about 0.25 diopters, up to about 0.33 diopters, and up to about 0.5 diopters as being physiologically correct, without the mismatch itself causing significant discomfort. In some embodiments, the display system (e.g., display system 250, FIG. 6) disclosed herein presents an image to the user that has a vergence-accommodation mismatch of about 0.5 diopters or less. In some other embodiments, the vergence-accommodation mismatch of the image provided by the display system is about 0.33 diopters or less. In still other embodiments, the vergence-accommodation mismatch of the image provided by the display system is about 0.25 diopters or less, including about 0.1 diopters or less.

[0134] FIG. 5 illustrates a side view of an approach for simulating a three-dimensional image by modifying wavefront divergence. The display system includes a waveguide 270 configured to receive light 770 encoded with image information and output the light to the user's eye 210. The waveguide 270 may output light 650 with a defined amount of wavefront divergence corresponding to the wavefront divergence of a light field generated by a point on a desired depth plane 240. In some embodiments, the same amount of wavefront divergence is provided for all objects presented on that depth plane. Additionally, the user's other eye would be illustrated as being provided with image information from a similar waveguide.

[0135] In some embodiments, a single waveguide may be configured to output light with a set amount of wavefront divergence corresponding to a single or limited number of depth planes, and / or the waveguide may be configured to output light of a limited range of wavelengths. As a result, in some embodiments, a stack of waveguides may be utilized to provide different amounts of wavefront divergence for different depth planes and / or to output light of different ranges of wavelengths. It should be understood that, as used herein, a depth plane may follow the contour of a planar or curved surface. In some embodiments, advantageously for simplicity, the depth plane may follow the contour of a flat surface.

[0136] FIG. 6 illustrates an example of a stack of waveguides for outputting image information to a user. The display system 250 includes a stack of waveguides or a stacked waveguide assembly 260 that can be utilized to provide three-dimensional perception to the eye / brain using waveguides 270, 280, 290, 300, 310. It should be understood that the display system 250 may be considered a light field display in some embodiments. Additionally, the waveguide assembly 260 may also be referred to as an eyepiece.

[0137] In some embodiments, the display system 250 may be configured to provide a substantially continuous cue for convergence / divergence movement and a plurality of discrete cues for depth adjustment. The cue for convergence / divergence movement may be provided by displaying different images to each of the user's eyes, and the cue for depth adjustment may be provided by outputting light that forms an image with a selectable discrete amount of wavefront divergence. In other words, the display system 250 may be configured to output light with a variable level of wavefront divergence. In some embodiments, each discrete level of wavefront divergence may correspond to a particular depth plane and may be provided by a particular one of waveguides 270, 280, 290, 300, 310.

[0138] Continuing to refer to FIG. 6, waveguide assembly 260 may also include features 320, 330, 340, 350 between the waveguides. In some embodiments, features 320, 330, 340, 350 may be one or more lenses. Waveguides 270, 280, 290, 300, 310 and / or features (lenses) 320, 330, 340, 350 may be configured to transmit image information to the eye with various levels of wavefront curvature or ray divergence. Each waveguide level may be associated with a particular depth plane and may be configured to output image information corresponding to that depth plane. Image input devices 360, 370, 380, 390, 400 may function as light sources for the waveguides and may be utilized to input image information into waveguides 270, 280, 290, 300, 310, each configured to disperse incident light across an individual waveguide for output toward eye 210 as described herein. Light exits from output surfaces 410, 420, 430, 440, 450 of image input devices 360, 370, 380, 390, 400 and is input into corresponding input surfaces 460, 470, 480, 490, 500 of waveguides 270, 280, 290, 300, 310. In some embodiments, input surfaces 460, 470, 480, 490, 500 may each be an edge of the corresponding waveguide or a portion of the major surface of the corresponding waveguide (i.e., one of the waveguide surfaces facing directly toward world 510 or user's eye 210). In some embodiments, a single beam of light (e.g., a collimated beam) may be input into each waveguide and output an entire field of cloned collimated beams directed toward eye 210 at a particular angle (and amount of divergence) corresponding to the depth plane associated with the particular waveguide. In some embodiments, a single one of image input devices 360, 370, 380, 390, 400 may be associated with and input light into one or more (e.g., three) of waveguides 270, 280, 290, 300, 310.

[0139] In some embodiments, the image input devices 360, 370, 380, 390, 400 are each discrete displays that generate image information for input into their respective waveguides 270, 280, 290, 300, 310. In some other embodiments, the image input devices 360, 370, 380, 390, 400 are the output ends of a single multiplexed display that can send image information, for example, via one or more optical waveguides (such as optical fiber cables) to each of the image input devices 360, 370, 380, 390, 400. It should be understood that the image information provided by the image input devices 360, 370, 380, 390, 400 can include light of different wavelengths or colors (e.g., different primary colors as discussed herein).

[0140] In some embodiments, the light input into the waveguides 270, 280, 290, 300, 310 is provided by an optical projector system 520, which includes an optical module 530 that may include a light emitter such as a light emitting diode (LED). The light from the optical module 530 may be directed via a beam splitter 550 to a light modulator 540, such as a spatial light modulator, and thereby modified. The light modulator 540 may be configured to vary the perceived intensity of the light input into the waveguides 270, 280, 290, 300, 310 and to encode the light with image information. Examples of spatial light modulators include liquid crystal displays (LCDs), including liquid crystal on silicon (LCOS) displays. The image input devices 360, 370, 380, 390, 400 are shown schematically and, in some embodiments, these image input devices may represent different optical paths and locations within a common projection system that are configured to output light into their associated waveguides 270, 280, 290, 300, 310. In some embodiments, the waveguides of the waveguide assembly 260 may function as an ideal lens while relaying the light input into the waveguides to the user's eye. In this concept, the object may be the spatial light modulator 540 and the image may be an image on a depth plane.

[0141] In some embodiments, the display system 250 may be a scanning fiber display comprising one or more scanning fibers configured to project light into one or more waveguides 270, 280, 290, 300, 310 in various patterns (e.g., raster scan, helical scan, Lissajous pattern, etc.) and ultimately into the user's eye 210. In some embodiments, the illustrated image input devices 360, 370, 380, 390, 400 may schematically represent a single scanning fiber or a bundle of scanning fibers configured to input light into one or more waveguides 270, 280, 290, 300, 310. In some other embodiments, the illustrated image input devices 360, 370, 380, 390, 400 may schematically represent one or more scanning fibers or one or more bundles of scanning fibers, each configured to input light into an associated one of the waveguides 270, 280, 290, 300, 310. It should be understood that the one or more optical fibers may be configured to transmit light from the optical module 530 to the one or more waveguides 270, 280, 290, 300, 310. It should be understood that one or more intervening optical structures are provided between the scanning fiber or fibers and the one or more waveguides 270, 280, 290, 300, 310 and may, for example, redirect light exiting the scanning fiber into the one or more waveguides 270, 280, 290, 300, 310.

[0142] Controller 560 controls the operation of one or more of the stacked waveguide assemblies 260, including the operation of the image input devices 360, 370, 380, 390, 400, the light source 530, and the light modulator 540. In some embodiments, controller 560 is part of the local data processing module 140. Controller 560 includes programming (e.g., instructions in a non-transitory medium) that adjusts the timing and provision of image information to waveguides 270, 280, 290, 300, 310, for example, according to any of the various schemes disclosed herein. In some embodiments, the controller may be a single integrated device or a distributed system connected by a wired or wireless communication channel. Controller 560 may, in some embodiments, also be part of processing module 140 or 150 (FIG. 9D).

[0143] Continuing to refer to FIG. 6, the waveguides 270, 280, 290, 300, 310 may be configured to propagate light within each individual waveguide by total internal reflection (TIR). The waveguides 270, 280, 290, 300, 310 may each be planar, or have another shape (e.g., curved), with a major top surface and a major bottom surface and an edge extending between their major top and bottom surfaces. In the illustrated configuration, the waveguides 270, 280, 290, 300, 310 each include external coupling optical elements 570, 580, 590, 600, 610 configured to extract light from the waveguide by redirecting the light propagating within each individual waveguide out of the waveguide and outputting the image information to the eye 210. Although referred to throughout this specification as “external coupling optical elements,” the external coupling optical elements need not be optical elements and may be non-optical elements. The extracted light may also be referred to as external coupled light, and the external coupling optical elements of the light may also be referred to as light extraction optical elements. The beam of extracted light may be output by the waveguide at the location where the light propagating within the waveguide impinges on the light extraction optical element. The external coupling optical elements 570, 580, 590, 600, 610 may be gratings, for example, including diffractive optical features as further discussed herein. For ease of explanation and clarity of the drawings, the external coupling optical elements 570, 580, 590, 600, 610 are shown disposed on the bottom major surface of the waveguides 270, 280, 290, 300, 310, but in some embodiments, the external coupling optical elements 570, 580, 590, 600, 610 may be disposed on the top major surface and / or the bottom major surface, and / or directly disposed within the volume of the waveguides 270, 280, 290, 300, 310, as further discussed herein. In some embodiments, the external coupling optical elements 570, 580, 590, 600, 610 may be attached to a transparent substrate and formed within a layer of the material forming the waveguides 270, 280, 290, 300, 310. In some other embodiments, the waveguides 270, 280, 290, 300, 310 may be a monolithic piece of material, and the external coupling optical elements 570, 580, 590, 600, 610 may be formed on and / or within the surface of the piece of material.

[0144] Continuing to refer to FIG. 6, as discussed herein, each of the waveguides 270, 280, 290, 300, 310 is configured to output light and form an image corresponding to a particular depth plane. For example, the waveguide 270 closest to the eye may be configured to deliver collimated light (input into such waveguide 270) to the eye 210. The collimated light may represent an optically infinite focal plane. The next upper waveguide 280 may be configured to deliver collimated light that passes through a first lens 350 (e.g., a negative lens) before reaching the eye 210. Such a first lens 350 may be configured to generate a slightly convex wavefront curvature such that the eye / brain interprets the light originating from the next upper waveguide 280 as originating from a first focal plane that is closer inwardly toward the eye 210 from the optically infinite. Similarly, the third upper waveguide 290 passes its output light through both the first lens 350 and the second lens 340 before reaching the eye 210. The combined refractive power of the first lens 350 and the second lens 340 may be configured to generate another incremental amount of wavefront curvature such that the eye / brain interprets the light originating from the third waveguide 290 as originating from a second focal plane that is closer inwardly toward the person from the optically infinite than the light from the next upper waveguide 280.

[0145] The other waveguide layers 300, 310 and lenses 330, 320 are similarly configured, and the top waveguide 310 in the stack sends its output through all of the lenses between it and the eye for the converging focusing power that represents the focal plane closest to the person. When viewing / interpreting light originating from the world 510 on the other side of the stacked waveguide assembly 260, a compensation lens layer 620 may be disposed on top of the stack to compensate for the stack of lenses 320, 330, 340, 350. Such a configuration provides the same number of perceived focal planes as there are available waveguide / lens pairs. Both the external coupling optical elements of the waveguides and the focusing sides of the lenses may be static (i.e., not dynamic or electroactive). In some alternative embodiments, one or both may be dynamic using electroactive features.

[0146] In some embodiments, two or more of the waveguides 270, 280, 290, 300, 310 may have the same associated depth plane. For example, a plurality of waveguides 270, 280, 290, 300, 310 may be configured to output images set to the same depth plane, or a plurality of subsets of the waveguides 270, 280, 290, 300, 310 may be configured to output images set to the same one or more depth planes, with one set per depth plane. This can provide the advantage of forming tiled images to provide an extended field of view in those depth planes.

[0147] Continuing to refer to FIG. 6, the external coupling optical elements 570, 580, 590, 600, 610 may be configured to redirect light from their respective waveguides for a particular depth plane associated with the waveguide and output the light with an appropriate amount of divergence or collimation. As a result, waveguides having different associated depth planes may have different configurations of the external coupling optical elements 570, 580, 590, 600, 610, which output light with different amounts of divergence depending on the associated depth plane. In some embodiments, the light extraction optical elements 570, 580, 590, 600, 610 may be volume features or surface features configured to output light at a specific angle. For example, the light extraction optical elements 570, 580, 590, 600, 610 may be volume holograms, surface holograms, and / or diffraction gratings. In some embodiments, the features 320, 330, 340, 350 may not be lenses. Rather, they may simply be spacers (e.g., structures for forming cladding layers and / or voids).

[0148] In some embodiments, the external coupling optical elements 570, 580, 590, 600, 610 are diffraction features or “diffractive optical elements” (also referred to herein as “DOEs”) that form a diffraction pattern. Preferably, the DOE has a sufficiently low diffraction efficiency such that only a portion of the light of the beam is deflected towards the eye 210 at each intersection of the DOE, while the remainder continues to travel through the waveguide via TIR. The light carrying the image information is thus split into several associated output beams that exit the waveguide at various locations, resulting in a very uniform pattern of output emission towards the eye 210 with respect to this particular collimated beam that bounces within the waveguide.

[0149] In some embodiments, one or more DOEs may be switchable between an “on” state where they actively diffract and an “off” state where they do not significantly diffract. For example, a switchable DOE may comprise a layer of polymer dispersed liquid crystal, in which microdroplets have a diffraction pattern in a host medium, and the refractive index of the microdroplets may be switched to substantially match that of the host material (in which case the pattern does not significantly diffract the incident light), or the microdroplets may be switched to a refractive index that does not match that of the host medium (in which case the pattern actively diffracts the incident light).

[0150] In some embodiments, a camera assembly 630 (e.g., a digital camera including visible and infrared cameras) may be provided to capture an image of the eye 210 and / or the tissue surrounding the eye 210, and for example, detect user input and / or monitor the user's physiological state. As used herein, a camera may be any image capture device. In some embodiments, the camera assembly 630 may include an image capture device and a light source (e.g., infrared light) that projects light onto the eye and then can be reflected by the eye and detected by the image capture device. In some embodiments, the camera assembly 630 may be attached to the frame 80 (FIG. 9D) and may communicate electrically with a processing module 140 and / or 150 that can process the image information from the camera assembly 630. In some embodiments, one camera assembly 630 may be utilized per eye to monitor each eye separately.

[0151] Referring now to FIG. 7, an example of an output beam output by a waveguide is shown. Although one waveguide is illustrated, it should be understood that other waveguides within the waveguide assembly 260 (FIG. 6) may function similarly, and the waveguide assembly 260 includes a plurality of waveguides. Light 640 is input into the waveguide 270 at the input surface 460 of the waveguide 270 and propagates through the waveguide 270 by TIR. At the point where the light 640 impinges on the DOE 570, a portion of the light exits the waveguide as the output beam 650. The output beam 650 is illustrated as being substantially parallel, but as discussed herein, it may also be redirected to propagate to the eye 210 at an angle (e.g., forming a diverging output beam) depending on the depth plane associated with the waveguide 270. It should be understood that a waveguide with an external coupling optical element that externally couples light to form an image that appears to be set in a depth plane at a long distance (e.g., optical infinity) from the eye 210 may be shown for the substantially parallel output beam. Other waveguides or other sets of external coupling optical elements may output a more divergent output beam pattern, which would require the eye 210 to focus at a closer distance and would be interpreted by the brain as light from a distance closer to the eye 210 than optical infinity.

[0152] In some embodiments, a full-color image may be formed in each depth plane by overlaying the image on each of the primary colors, e.g., three or more primary colors. FIG. 8 illustrates an example of a stacked waveguide assembly in which each depth plane includes an image formed using a plurality of different primary colors. The illustrated embodiment shows depth planes 240a-240f, although more or fewer depths may also be considered. Each depth plane may have three or more primary color images associated therewith, including a first image of a first color G, a second image of a second color R, and a third image of a third color B. Different depth planes are shown in the figure by different numbers associated with the diopters (dpt) following the letters G, R, and B. As a mere example, the numbers following each of these letters indicate the diopter (1 / m), i.e., the inverse distance of the depth plane from the user, and each box in the figure represents an individual primary color image. In some embodiments, the exact location of the depth planes for different primary colors may vary to account for differences in the focusing of light of different wavelengths by the eye. For example, the different primary color images for a given depth plane may be placed on a depth plane corresponding to a different distance from the user. Such an arrangement may increase visual acuity and user comfort and / or reduce chromatic aberration.

[0153] In some embodiments, the light of each primary color may be output by a single dedicated waveguide, and as a result, each depth plane may have a plurality of waveguides associated therewith. In such embodiments, each box in the figure, including those containing the letters G, R, or B, may be understood to represent an individual waveguide, and three waveguides may be provided for each depth plane such that three primary color images are provided for each depth plane. The waveguides associated with each depth plane are shown adjacent to each other in this figure for ease of explanation, but it should be understood that in a physical device, all of the waveguides may be arranged in a stack with one waveguide per level. In some other embodiments, a plurality of primary colors may be output by the same waveguide, e.g., such that only a single waveguide is provided for each depth plane.

[0154] Continuing to refer to FIG. 8, in some embodiments, G is green, R is red, and B is blue. In some other embodiments, other colors associated with other wavelengths of light, including magenta and cyan, may also be used in addition to, or in place of, one or more of red, green, or blue.

[0155] It should be understood that references throughout this disclosure to the color of a given light are understood to encompass light of one or more wavelengths within the range of wavelengths of the light that is perceived by the user as being that given color. For example, red light may include light of one or more wavelengths within the range of about 620 - 780 nm, green light may include light of one or more wavelengths within the range of about 492 - 577 nm, and blue light may include light of one or more wavelengths within the range of about 435 - 493 nm.

[0156] In some embodiments, the light source 530 (FIG. 6) may be configured to emit light of one or more wavelengths outside the user's visual perception range, such as infrared and / or ultraviolet wavelengths. Additionally, the internal coupling, external coupling, and other light redirection structures of the waveguide of the display 250 may be configured to direct and emit this light from the display towards the user's eye 210, for example, for imaging and / or user stimulation applications.

[0157] Referring now to FIG. 9A, in some embodiments, light impinging on a waveguide may need to be redirected to internally couple the light into the waveguide. An internal coupling optical element may be used to redirect and internally couple the light into its corresponding waveguide. Although the term "internal coupling optical element" is referred to throughout this specification, an internal coupling optical element need not be an optical element and may be a non-optical element. FIG. 9A illustrates a cross-sectional side view of an example of a set 660 of stacked waveguides, each including an internal coupling optical element. Each waveguide may be configured to output light of one or more different wavelengths or one or more different wavelength ranges. Stack 660 may correspond to stack 260 (FIG. 6), and the illustrated waveguides of stack 660 may correspond to a portion of waveguides 270, 280, 290, 300, 310, but it should be understood that light from one or more of image input devices 360, 370, 380, 390, 400 is input into the waveguide at a location where the light is required to be redirected for internal coupling.

[0158] The illustrated set 660 of stacked waveguides includes waveguides 670, 680, and 690. Each waveguide includes an associated internal coupling optical element (which may also be referred to as an optical input area on the waveguide). For example, internal coupling optical element 700 is disposed on a major surface (e.g., the upper major surface) of waveguide 670, internal coupling optical element 710 is disposed on a major surface (e.g., the upper major surface) of waveguide 680, and internal coupling optical element 720 is disposed on a major surface (e.g., the upper major surface) of waveguide 690. In some embodiments, one or more of the internal coupling optical elements 700, 710, 720 may be disposed on the bottom major surface of the respective waveguides 670, 680, 690 (in particular, one or more of the internal coupling optical elements are reflective deflecting optical elements). As illustrated, the internal coupling optical elements 700, 710, 720 may be disposed on the upper major surface (or the upper portion of the next lower waveguide) of their respective waveguides 670, 680, 690, and in particular, those internal coupling optical elements are transmissive deflecting optical elements. In some embodiments, the internal coupling optical elements 700, 710, 720 may be disposed within the bodies of the respective waveguides 670, 680, 690. In some embodiments, as discussed herein, the internal coupling optical elements 700, 710, 720 are wavelength selective such that they selectively redirect one or more wavelengths of light while transmitting other wavelengths of light. Although illustrated on one side or corner of their respective waveguides 670, 680, 690, it should be understood that the internal coupling optical elements 700, 710, 720 may, in some embodiments, be disposed within other areas of their respective waveguides 670, 680, 690.

[0159] As shown, the internally coupled optical elements 700, 710, 720 may be laterally offset from each other. In some embodiments, each internally coupled optical element may be offset so that it receives light without the light passing through another internally coupled optical element. For example, each internally coupled optical element 700, 710, 720 may be configured to receive light from different image input devices 360, 370, 380, 390, and 400, as shown in FIG. 6, and may be separated (e.g., laterally spaced) from other internally coupled optical elements 700, 710, 720 so as to substantially not receive light from other ones of the internally coupled optical elements 700, 710, 720.

[0160] Each waveguide also includes an associated light dispersing element. For example, the light dispersing element 730 is disposed on a major surface (e.g., the upper major surface) of the waveguide 670, the light dispersing element 740 is disposed on a major surface (e.g., the upper major surface) of the waveguide 680, and the light dispersing element 750 is disposed on a major surface (e.g., the upper major surface) of the waveguide 690. In some other embodiments, the light dispersing elements 730, 740, 750 may be disposed on the bottom major surfaces of the associated waveguides 670, 680, 690, respectively. In some other embodiments, the light dispersing elements 730, 740, 750 may be disposed on both the upper and bottom major surfaces of the associated waveguides 670, 680, 690, respectively, or the light dispersing elements 730, 740, 750 may be disposed on different ones of the upper and bottom major surfaces within different associated waveguides 670, 680, 690, respectively.

[0161] Waveguides 670, 680, 690 may be separated and isolated, for example, by a gas, liquid, and / or solid layer of material. For example, as shown, layer 760a may separate waveguides 670 and 680, and layer 760b may separate waveguides 680 and 690. In some embodiments, layers 760a and 760b are formed from a low refractive index material (i.e., a material having a refractive index lower than the material forming the nearest of waveguides 670, 680, 690). Preferably, the refractive index of the material forming layers 760a, 760b is 0.05 or more, or 0.10 or less, relative to the refractive index of the material forming waveguides 670, 680, 690. Advantageously, the lower refractive index layers 760a, 760b may function as cladding layers that facilitate total internal reflection (TIR) of light (e.g., TIR between the upper major surface and the lower major surface of each waveguide) through waveguides 670, 680, 690. In some embodiments, layers 760a, 760b are formed from air. It should be understood that although not shown, the upper and lower portions of the illustrated set 660 of waveguides may include a nearest cladding layer.

[0162] Preferably, for ease of manufacturing and other considerations, the materials forming waveguides 670, 680, 690 are similar or identical, and the materials forming layers 760a, 760b are similar or identical. In some embodiments, the materials forming waveguides 670, 680, 690 may be different between one or more waveguides, and / or the materials forming layers 760a, 760b may still be different while maintaining the various refractive index relationships described above.

[0163] Continuing to refer to FIG. 9A, light rays 770, 780, 790 are incident on the set 660 of waveguides. It should be understood that light rays 770, 780, 790 may be input into waveguides 670, 680, 690 by one or more image input devices 360, 370, 380, 390, 400 (FIG. 6).

[0164] In some embodiments, the light rays 770, 780, 790 may have different properties, such as different wavelengths or different wavelength ranges, corresponding to different colors. The internal coupling optical elements 700, 710, 720 each deflect the incident light so that the light propagates through an individual one of the waveguides 670, 680, 690 by TIR. In some embodiments, the internal coupling optical elements 700, 710, 720 each selectively deflect one or more specific wavelengths of light while transmitting other wavelengths to the underlying waveguide and the associated internal coupling optical element.

[0165] For example, the internal coupling optical element 700 may be configured to deflect the light ray 770 having the first wavelength or wavelength range while transmitting the light rays 780 and 790 having different second and third wavelengths or wavelength ranges, respectively. The transmitted light ray 780 impinges on the internal coupling optical element 710 configured to deflect the light of the second wavelength or wavelength range, and is thereby deflected. The light ray 790 is deflected by the internal coupling optical element 720 configured to selectively deflect the light of the third wavelength or wavelength range.

[0166] Continuing to refer to FIG. 9A, the deflected light rays 770, 780, 790 are deflected to propagate through the corresponding waveguides 670, 680, 690. That is, the internal coupling optical elements 700, 710, 720 of each waveguide deflect the light into its corresponding waveguide 670, 680, 690 and internally couple the light into its corresponding waveguide. The light rays 770, 780, 790 are deflected at an angle that causes the light to propagate through the individual waveguides 670, 680, 690 by TIR. The light rays 770, 780, 790 propagate through the individual waveguides 670, 680, 690 by TIR until they impinge on the corresponding light dispersion elements 730, 740, 750 of the waveguide.

[0167] Referring now to FIG. 9B, a perspective view of an embodiment of the plurality of stacked waveguides of FIG. 9A is illustrated. As described above, the internally coupled light rays 770, 780, 790 are each deflected by the internally coupled optical elements 700, 710, 720 and then each propagate by TIR within the waveguides 670, 680, 690. The light rays 770, 780, 790 then each impinge on the light dispersion elements 730, 740, 750. The light dispersion elements 730, 740, 750 each deflect the light rays 770, 780, 790 so as to propagate towards the externally coupled optical elements 800, 810, 820.

[0168] In some embodiments, the optical dispersion elements 730, 740, 750 are orthogonal pupil expanders (OPEs). In some embodiments, the OPE deflects or disperses light to the external coupling optical elements 800, 810, 820, and in some embodiments may also increase the beam or spot size of the present light as it propagates to the external coupling optical elements. In some embodiments, the optical dispersion elements 730, 740, 750 may be omitted, and the internal coupling optical elements 700, 710, 720 may be configured to deflect light directly to the external coupling optical elements 800, 810, 820. For example, referring to FIG. 9A, the optical dispersion elements 730, 740, 750 may each be replaced with the external coupling optical elements 800, 810, 820. In some embodiments, the external coupling optical elements 800, 810, 820 are an exit pupil (EP) or an exit pupil expander (EPE) that directs light to the eye 210 (FIG. 7). It should be understood that the OPE may be configured to increase the size of the eyebox in at least one axis, and the EPE may increase the eyebox in an axis that intersects, for example, is orthogonal to, the axis of the OPE. For example, each OPE may be configured to redirect a portion of the light impinging on the OPE to the EPE of the same waveguide while allowing the remainder of the light to continue to propagate along the waveguide. In response to colliding again with the OPE, another portion of the remaining light is redirected to the EPE, and the remainder of that portion continues to propagate further along the waveguide, and so on. Similarly, in response to impinging on the EPE, a portion of the colliding light is directed out of the waveguide towards the user, and the remainder of that light continues to propagate through the waveguide until it impinges again on the EP, at which point another portion of the colliding light is directed out of the waveguide, and so on. As a result, a single beam of internally coupled light is "replicated" each time a portion of that light is redirected by the OPE or EPE, thereby forming a beam field of cloned light as shown in FIG. 6. In some embodiments, the OPE and / or EPE may be configured to modify the size of the beam of light.

[0169] Thus, referring to FIGS. 9A and 9B, in some embodiments, the waveguide set 660 includes, for each primary color, waveguides 670, 680, 690, internal coupling optical elements 700, 710, 720, light dispersion elements (e.g., OPEs) 730, 740, 750, and external coupling optical elements (e.g., EPs) 800, 810, 820. The waveguides 670, 680, 690 may be stacked with a gap / cladding layer between each one. The internal coupling optical elements 700, 710, 720 redirect or deflect the incident light into their respective waveguides (using different internal coupling optical elements that receive light of different wavelengths). The light then propagates at an angle that will result in TIR within the individual waveguides 670, 680, 690. In the example shown, the ray 770 (e.g., blue light) is polarized by the first internal coupling optical element 700 in the manner described above, then bounces along the waveguide and interacts with the light dispersion element (e.g., OPE) 730 and then the external coupling optical element (e.g., EP) 800. The rays 780 and 790 (e.g., green and red light, respectively) pass through the waveguide 670, and the ray 780 collides with the internal coupling optical element 710 and is thereby deflected. The ray 780 then bounces along the waveguide 680 via TIR and will proceed to its light dispersion element (e.g., OPE) 740 and then the external coupling optical element (e.g., EP) 810. Finally, the ray 790 (e.g., red light) passes through the waveguide 690 and collides with the internal coupling optical element 720 of the waveguide 690. The internal coupling optical element 720 deflects the ray 790 such that the ray propagates, via TIR, to the light dispersion element (e.g., OPE) 750 and then, via TIR, to the external coupling optical element (e.g., EP) 820. The external coupling optical element 820 then finally externally couples the ray 790 to the user, who also receives the externally coupled light from the other waveguides 670, 680.

[0170] FIG. 9C illustrates a top and bottom plan view of an embodiment of a plurality of stacked waveguides of FIGS. 9A and 9B. As shown, waveguides 670, 680, 690 may be vertically aligned with associated optical dispersion elements 730, 740, 750 and associated external coupling optical elements 800, 810, 820 of each waveguide. However, as discussed herein, internal coupling optical elements 700, 710, 720 are not vertically aligned. Rather, the internal coupling optical elements are preferably non-overlapping (e.g., laterally spaced as seen in the top and bottom views). As further discussed herein, this non-overlapping spatial arrangement facilitates the injection of light from different resources into different waveguides on a one-to-one basis, thereby enabling a specific light source to be uniquely coupled to a specific waveguide. In some embodiments, an array comprising non-overlapping spatially separated internal coupling optical elements may be referred to as a deflected pupil system, and the internal coupling optical elements within these arrays may correspond to sub-pupils.

[0171] FIG. 9D illustrates an embodiment of a wearable display system 60 in which various waveguides and related systems disclosed herein may be integrated. In some embodiments, display system 60 is the system 250 of FIG. 6, and FIG. 6 schematically shows some parts of that system 60 in more detail. For example, the waveguide assembly 260 of FIG. 6 may be part of display 70.

[0172] Continuing to refer to FIG. 9D, the display system 60 includes a display 70 and various mechanical and electronic modules and systems to support the functions of the display 70. The display 70 may be coupled to a frame 80, which is wearable by a display system user or user 90 and is configured to position the display 70 in front of the user 90's eyes. In some embodiments, the display 70 may be regarded as an eyepiece. In some embodiments, a speaker 100 is coupled to the frame 80 and configured to be positioned adjacent to the user 90's external ear canal (in some embodiments, another speaker, not shown, may optionally be positioned adjacent to the other external ear canal of the user to provide stereo / formable sound control). The display system 60 may also include one or more microphones 110 or other devices to detect sound. In some embodiments, the microphone is configured to enable the user to provide an input or command to the system 60 (e.g., selection of an audio menu command, natural language question, etc.) and / or enable audio communication with other persons (e.g., other users of a similar display system). The microphone may further be configured as a peripheral sensor to collect audio data (e.g., sound from the user and / or the environment). In some embodiments, the display system 60 may further include one or more outwardly directed environmental sensors 112 configured to detect objects, stimuli, people, animals, places, or other aspects of the world around the user. For example, the environmental sensor 112 may include one or more cameras that may be positioned facing outward to capture an image similar to at least a portion of the user 90's normal field of view. In some embodiments, the display system may also include a peripheral sensor 120a, which is separate from the frame 80 and may be attached to the user 90's body (e.g., the user 90's head, torso, limbs, etc.). The peripheral sensor 120a may be configured to obtain data characterizing the physiological state of the user 90 in some embodiments. For example, the sensor 120a may be an electrode.

[0173] Continuing to refer to FIG. 9D, display 70 is operatively coupled to local data processing module 140 by a communication link 130, such as a wired conductor or wireless connectivity, which may be mounted in various configurations, such as fixedly attached to a helmet or hat worn by a user, fixedly attached to a headset, embedded within a headset, or alternatively removably attached to user 90 (e.g., in a backpack configuration, in a belt attachment configuration). Similarly, sensor 120a may be operatively coupled to local processor and data module 140 by a communication link 120b, such as a wired conductor or wireless connectivity. Local processing and data module 140 may include digital memory, such as a hardware processor and non-volatile memory (e.g., flash memory or hard disk drive), both of which may be utilized to assist in the processing, caching, and storage of data. Optionally, local processing and data module 140 may include one or more central processing units (CPUs), graphics processing units (GPUs), dedicated processing hardware, etc. The data may include a) data captured from sensors (image capture devices (such as cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, wireless devices, gyroscopes, and / or other sensors disclosed herein (e.g., operatively coupled to frame 80 or alternatively attachable to user 90)), and / or b) data obtained and / or processed using remote processing module 150 and / or remote data repository 160 (including data related to virtual content), possibly for passage to display 70 after processing or retrieval. Local processing and data module 140 may be operatively coupled to remote processing module 150 and remote data repository 160 by communication links 170, 180, such as via a wired or wireless communication link, such that these remote modules 150, 160 are operatively coupled to each other and available as resources to local processing and data module 140.In some embodiments, the local processing and data module 140 may include one or more of an image capture device, a microphone, an inertial measurement unit, an accelerometer, a compass, a GPS unit, a wireless device, and / or a gyroscope. In some other embodiments, one or more of these sensors may be attached to the frame 80 or may be of an independent structure that communicates with the local processing and data module 140 via a wired or wireless communication path.

[0174] Continuing to refer to FIG. 9D, in some embodiments, the remote processing module 150 may include one or more processors configured to analyze and process data and / or image information, for example, including one or more central processing units (CPUs), graphics processing units (GPUs), dedicated processing hardware, and the like. In some embodiments, the remote data repository 160 may include a digital data storage facility that may be available through the Internet or other networking configurations in a "cloud" resource configuration. In some embodiments, the remote data repository 160 may include one or more remote servers that provide information, for example, information for generating augmented reality content to the local processing and data module 140 and / or the remote processing module 150. In some embodiments, all data is stored and all calculations are performed within the local processing and data module, enabling fully autonomous use from the remote module. Optionally, an external system (e.g., one or more processors, one or more computer systems) including a CPU, GPU, etc. may perform at least a portion of the processing (e.g., generating image information, processing data), for example, providing information to and receiving information from modules 140, 150, 160 via a wireless or wired connection.

[0175] FIG. 10 is a schematic diagram illustrating a projector assembly 1000 that uses a polarization beam splitter (PBS) 1020 to illuminate a spatial light modulator (SLM) 1030 and redirect light from the SLM 1030 through a projection optical system 1040 to an eyepiece (not shown). The projector assembly 1000 includes an illumination source 1010, which can include, for example, a light emitting diode (LED), a laser (e.g., a laser diode), or other types of light sources. This light may be collimated by a collimating optical system. The illumination source 1010 can emit polarized, unpolarized, or partially polarized light. In the illustrated design, the illumination source 1010 may emit light 1012 that is polarized to have p-polarization. A first optical element 1015 (e.g., a pre-polarizer) is aligned to pass light with a first polarization (e.g., p-polarization).

[0176] This light is directed towards a polarization beam splitter 1020. First, the light passes through an interface 1022 (e.g., a polarization interface) of the PBS 1020 configured to transmit light of a first polarization (e.g., p-polarization). Thus, the light continues and is incident on the spatial light modulator 1030. As shown, the SLM 1030 is a reflective SLM configured to retroreflect the incident light and selectively modulate the light. The SLM 1030 includes, for example, one or more pixels that can have different states. The light incident on an individual pixel can be modulated based on the state of the pixel. Thus, the SLM 1030 can be driven to modulate the light so as to provide an image. In this embodiment, the SLM 1030 may be a polarization-based SLM that modulates the polarization of the light incident thereon. For example, in the on state, the pixels of the SLM 1030 change the input light from a first polarization state (e.g., p-polarization state) to a second polarization state (e.g., s-polarization state) such that a bright state (e.g., a white pixel) is shown. The second polarization state may be the first polarization state that is modulated (e.g., rotated) by 90°. In the on state, the light having the second polarization state is reflected by the interface 1022 and propagates downstream of the projector optics 1040. In the off state, the SLM 1030 does not change the polarization state of the light incident thereon, e.g., does not rotate the input light from the first polarization state, and thus a dark state (e.g., a black pixel) is shown. In the off state, the light having the first polarization state is transmitted through the interface 1022 and propagates upstream so as to return to the illumination source 1010 instead of the user's eye.

[0177] After reflection from the SLM 1030, a portion of the light 1014 (e.g., the modulated light) is reflected from the interface 1022, exits the PBS 1020, and is directed towards the user's eye. The emitted light passes through the projector optics 1040 and is imaged onto an internal conjugate grid (ICG) 1050 of an eyepiece lens (not shown).

[0178] FIG. 11A illustrates a system (e.g., an augmented reality display system) 1100A for presenting an image to a user's eye 210 and for viewing the world 510, having an alternative configuration to that shown in FIG. 10. The system 1100 includes a light source 1110, a spatial light modulator (SLM) 1140, and an optical waveguide 1120 arranged such that light from the light source 1110 is coupled into the optical waveguide 1120 so as to illuminate the SLM 1140 and the light reflected from the SLM 1140 is directed towards the eye 210. The system 1100A includes an optical system 1130 arranged to perform both illuminating the SLM 1140 and projecting an image of the SLM 1140. Light from the light source 1110 propagates, for example, in a first direction through the optical system 1130 onto the SLM 1140, thereby illuminating the SLM 1140. The light reflected from the SLM 1140 propagates again through the optical system 1130 in a second direction opposite to the first direction, is directed towards the optical waveguide 1120, and is coupled therein.

[0179] The light source 1110 may include a light-emitting diode (LED), a laser (e.g., a laser diode), or other types of light sources. The light source 1110 may be a polarizer, however, the light source 1110 need not be so limited. In some implementations, the polarizer 1115 may be positioned between the light source 1110 and the SLM 1140. As shown, the polarizer 1115 is between the light source 1110 and the waveguide 1120. This polarizer 1115 may also be an optical recycler that transmits light of a first polarization and reflects light of a second polarization back to the light source 1110. Such a polarizer 1115 may be, for example, a wire grid polarizer. A coupling optical system 1105 such as an anamorphic optical element (e.g., a cone, a compound parabolic concentrator (CPC), a lens), etc. may be arranged with respect to the light source 1110 and receive the light output from the light source 1110. The coupling optical system 1105 may collect the light from the light source 1110 and, in some cases, may reduce the divergence of the light emitted from the light source 1110. The coupling optical system 1105 may, for example, collimate the light output from the light source 1110. The coupling optical system 1105 may collect light that matches the angular spectral field of view of the system 1100A. Thus, the coupling optical system 1105 may match the angular spectrum of the light output by the light source 1110 with the field of view of the system 1100A. The coupling optical system 1105 may have an asymmetric profile and act asymmetrically on the light emitted from the light source 1110. For example, the coupling optical system 1105 may reduce the divergence in orthogonal directions (e.g., the x and z directions) by different amounts. Such an asymmetry in the coupling optical system 1105 may address the asymmetry in the light emitted from the light source 1110, which may include, for example, a laser diode that emits a wider range of angles of light in one direction (e.g., x or z) as opposed to orthogonal directions (e.g., z or x respectively).

[0180] As discussed above, system 1100A includes an optical system 1130 configured to illuminate an SLM 1140, which is disposed within the optical path between a light source 1110 and the SLM 1140. The optical system 1130 may include a transmissive optical system that transmits light from the light source 1110 to the SLM 1140. The optical system 1130 may also be configured to project an image of the SLM 1140 or may be formed in the waveguide 1120 by the SLM 1140. The image may be projected into the eye of the eye 210. In some designs, the optical system 1130 may include one or more lenses or optical elements having refractive power. The optical system 1130 may, for example, have positive refractive power. The optical system 1130 may include one or more refractive optical elements such as refractive lenses. Other types of optical elements may also potentially be used.

[0181] The SLM 1140 may be reflective, modulate light, and reflect it therefrom. The SLM 1140 may be a polarization-based SLM configured to modulate polarization. The SLM 1140 may include, for example, a liquid crystal (LC) SLM (e.g., a liquid crystal on silicon (LCOS) SLM). The LC SLM may include, for example, a twisted nematic (TN) liquid crystal. The SLM 1140 may be substantially similar to the SLM 1030 referenced in FIG. 10. The SLM 1140 may include, for example, one or more pixels configured to selectively modulate light incident on the pixels depending on the state of the pixels. For some types of SLM 1140, the pixels may modulate the beam incident thereon by modifying the polarization state, such as by rotating the polarization (e.g., rotating the orientation of linearly polarized light).

[0182] As discussed above, the SLM 1140 may be an LCOS SLM 1140. In a crossed polarizer configuration, the LCOS SLM 1140 may nominally be white. When the pixel is off (e.g., 0 volts), it has a bright state, and when the pixel is on (e.g., a voltage above the threshold on voltage), it has a dark state. In this crossed polarizer configuration, leakage is minimized when the pixel is on and has a dark state.

[0183] In a parallel polarizer configuration, the LCOS SLM 1140 is nominally black. When the pixel is off (e.g., 0 volts), it has a dark state, and when the pixel is on (e.g., a voltage above the threshold on voltage), it has a bright state. In this parallel polarizer configuration, leakage is minimized when the pixel is off and has a dark state. The dark state may be (re)optimized using the wiping direction and the compensator angle. The compensator angle may refer to the angle of the compensator, which may be, for example, between the optical system 1130 and the SLM 1140 as shown in FIG. 20B.

[0184] The dynamic range and throughput for the parallel polarizer configuration may be different from those of the crossed polarizer configuration. Further, the parallel polarizer configuration may be optimized for contrast differently from the cross polarizer configuration.

[0185] System 1100A includes a waveguide 1120 for outputting image information to the eye 210. The waveguide 1120 may be substantially similar to the waveguides 270, 280, 290, 300, 310, 670, 680, and 690 discussed above. The waveguide 1120 may include a substantially transparent material having a refractive index sufficient to guide light therein. As shown, the waveguide 1120 may include a first side 1121, a second side 1123 opposite the first side 1121, corresponding upper and lower major surfaces, and an edge around it. The first and second major surfaces 1121, 1123 may be sufficiently flat so that image information can be retained in response to the light from the SLM 1140 propagating to the eye 210 such that the image formed by the SLM 1140 can be projected into the eye. The optical system 1130 and the SLM 1140 may be positioned on the first side 1121 of the waveguide 1120. The light source 1110 may be disposed on the second side 1123 such that the light from the light source 1110 is incident on the second side 1123 prior to passing through the waveguide 1120 and through the optical system 1130 to the SLM 1140. Thus, the waveguide 1120 may be disposed between the light source 1110 and the optical system 1130. In addition, at least a portion of the waveguide 1120 may extend between the light source 1110 and the optical system 1130, thereby allowing light to pass through a portion of the waveguide 1120 to the optical system 1130. The light emitted from the light source 1110 may thus be directed through the waveguide 1120, into and through the optical system 1130, and incident on the SLM 1140. The SLM 1140 reflects the light back through the optical system 1130 and back into the waveguide 1120.

[0186] System 1100A also includes an internal coupling optical element 1160 for coupling light from the optical system 1130 into the waveguide 1120. The internal coupling optical element 1160 may be disposed on a major surface of the waveguide 1120 (e.g., the upper major surface 1123). In some designs, the internal coupling optical element 1160 may be disposed on the lower major surface 1121 of the waveguide 1120. In some designs, the internal coupling optical element 1160 may be disposed within the body of the waveguide 1120. Although illustrated on one side or corner of the waveguide 1120, the internal coupling optical element 1160 may be disposed within / on other areas of the waveguide 1120. The internal coupling optical element 1160 may be substantially similar to the internal coupling optical elements 700, 710, 720 described above with reference to FIGS. 9A, 9B, and 9C. The internal coupling optical element 1160 may be a diffractive optical element or a reflector. Other structures may also be used as the internal coupling optical element 1160. The internal coupling optical element 1160 is configured to direct light incident thereon at a sufficiently large angle of incidence (e.g., greater than the critical angle) with respect to the upper and lower major surfaces 1123, 1121 of the waveguide 1120 so as to be guided therein by total internal reflection. Further, the internal coupling optical element 1160 may be operative over a wide range of wavelengths and thus may be configured to couple light of multiple colors into the waveguide 1120. For example, the internal coupling optical element 1160 may be configured to couple red, green, and blue light into the waveguide 1120. The light source 1110 may emit red, green, and blue light at different times.

[0187] System 1100A includes an optical dispersion element 1170 disposed on or within waveguide 1120. The optical dispersion element 1170 may be substantially similar to the optical dispersion elements 730, 740, and 750 described above with respect to FIG. 9B. For example, the optical dispersion element 1170 may be an orthogonal pupil expander (OPE). The optical dispersion element 1170 may be configured to diffuse light within waveguide 1120 by redirecting light propagating in the x direction, for example, in the z direction as illustrated in the top view of FIG. 11B. The optical dispersion element 1170 may thus be configured to increase the dimensions of the eye box along the z-axis (see FIG. 11B). The optical dispersion element 1170 may include one or more diffractive optical elements configured to diffract light propagating within waveguide 1120 incident on the diffractive optical element, for example, to redirect the light, for example, in a substantially orthogonal direction. Other configurations are also possible.

[0188] As shown in FIG. 11B, system 1100A may also include an external coupling optical element 1180 for coupling light from waveguide 1120 out to eye 210. The external coupling optical element 1180 may be configured to redirect light propagating within waveguide 1120 by total internal reflection (TIR) at an angle more normal to the upper major surface and / or lower major surface 1123, 1121 of waveguide 1120 so that the light is not guided within waveguide 1120. Instead, this light is directed out of waveguide 1120, for example, through the lower major surface 1121. The external coupling optical element 1180 may include one or more diffractive optical elements configured to diffract light propagating within waveguide 1120 incident on the diffractive optical element, for example, to redirect the light out of waveguide 1120. Other configurations are also possible.

[0189] FIG. 11B also shows the location of internal coupling optical element 1160, which is disposed laterally with respect to light dispersing optical element (e.g., cross-pupil expander) 1170 and external coupling optical element 1180. FIG. 11B also shows the location of light source 1110, which is disposed laterally with respect to internal coupling optical element 1160, light dispersing optical element (e.g., cross-pupil expander) 1170, and external coupling optical element 1180.

[0190] During operation, the light source 1110 of the system 1100A emits light into the coupling optical system 1105 through the polarizer 1115. This light is thus polarized, for example, linearly polarized in a first direction. This polarization is transmitted through the waveguide 1120, incident on the second major surface of the waveguide 1120, and may exit from the first major surface of the waveguide 1120. This light may propagate to the SLM 1140 through the optical system 1130. The optical system 1130 collimates and / or selects the light from the light source 1110, thereby modulating the polarization of the light incident thereon, for example, by selectively rotating the orientation of the modulator for each pixel according to the state of the pixel, and may include a polarization-based modulator that illuminates the SLM 1140. For example, the first pixel may be in a first state and may rotate the polarization, while the second pixel may be in a second state and may not rotate the polarization. The light between the coupling optical system 1105 and the optical system 1130 may illuminate the SLM 1140 very uniformly. After being incident on the SLM 1140, the light is reflected back through the optical system 1130. The optical system 1130 may be configured to project the image from the SLM 1140 into the waveguide 1120 and finally into the eye 210 so that the image is visible to the eye 210. In some designs, the retina of the eye 210 is optically conjugate to the image formed by and / or on the SLM 1140. The refractive power of the optical system 1130 may facilitate the projection of the image on the SLM 1140 into the eye 210 and onto the retina of the eye 210. In some implementations, for example, the refractive power provided by the external coupling optical element 1180 may assist and / or affect the image finally formed within the eye 210. The optical system 1130 acts as a projection lens as the light reflected from the SLM 1140 travels through the optical system towards the waveguide 1120. The optical system may generally function as the Fourier transform of the image on the SLM 1140 with respect to the plane within the waveguide 1120 near the internal coupling optical element 1160. Together, the two passes through the optical system 1130 (the first pass from the light source 1110 to the SLM 1140 and the second pass from the SLM 1140 to the waveguide 1120) may generally act to image the pupil of the coupling optical system 1105.The alignment and orientation of the light source 1110 (optionally, also the coupling optical system 1105 and / or the polarizer 1115), the optical system 1130, and the SLM 1140 are such that the light from the light source 1110 reflected from the SLM 1140 is directed onto the internal coupling optical element 1160. The pupil associated with the coupling optical system 1105 may be aligned with the internal coupling optical element 1160. The light may pass through an analyzer 1150 (e.g., a polarizer) within the optical path between the SLM 1140 and the eye 210. As depicted in FIG. 11A, the analyzer (e.g., polarizer) 1150 may be disposed within the optical path between the optical system 1130 and the internal coupling optical element 1160. The analyzer 1150 may be, for example, a linear polarizer having an orientation that transmits light of a first polarization (p-polarization) and blocks light of a second polarization (s-polarization), or vice versa. The analyzer 1150 may be a cleanup polarizer that further blocks polarized light blocked by another polarizer between the SLM 1140 and the analyzer 1150 or within the SLM 1140. The analyzer 1150 may be, for example, a circular polarizer that acts as an isolator and reduces reflections from the internal coupling optical element 1160 of the waveguide 1120 back towards the SLM 1140. The analyzer 1150 may include a wire grid polarizer, such as an absorptive wire grid polarizer, that is any of the polarizers disclosed herein. Such polarizers can result in significant absorption of unwanted light and thus increased contrast. Some such polarizers can be fabricated to include one or more dielectric layers over the wires and / or multilayer films. In some implementations, the SLM 1140 may be a liquid crystal on silicon (LCOS) SLM and may include an LC cell and a retarder (e.g., a compensator). In some implementations, the analyzer 1150 may be a compensator intended to provide more consistent polarization rotation (e.g., 90°) of the SLM 1140 for different angles of incidence and different wavelengths. Compensators may be used to improve the contrast of a display by improving the rotational polarization of light rays incident across various angles and wavelengths.For example, as light passes through analyzer 1150, SLM1140 may include a TN LCOS configured to rotate incident light of a first polarization (e.g., s-polarization) to a second polarization (e.g., p-polarization) for a first pixel, producing a bright pixel state. Conversely, SLM1140 may be configured such that for a second pixel, as light is attenuated or blocked by analyzer 1150, the reflected light remains in the first polarization, producing a dark pixel state, without rotating the incident light of the first polarization (e.g., s-polarization) to the second polarization (e.g., p-polarization). In such a configuration, polarizer 1115 closer to light source 1110 along the optical path may be oriented differently (e.g., orthogonally) with respect to analyzer 1150 further from light source 1110 along the optical path. Other configurations, for example, opposite configurations, are also conceivable as possibilities.

[0191] The light is then deflected, e.g., redirected, by the internal coupling optical element 1160 so as to be induced within the waveguide 1120 and propagate by TIR. The light then impinges on the light dispersing element 1170, redirecting the light in another direction (e.g., more towards the z-direction), causing an increase in the dimensions of the eyebox along the direction of the z-axis as shown in FIG. 11B. The light is thus deflected towards the external coupling optical element 1180, which directs the light from the waveguide 1120 out towards the eye 210 (e.g., the user's eye as shown). The light that is externally coupled along the z-direction by different portions of the external coupling optical element 1180 causes an increase in the dimensions of the eyebox, at least along a direction parallel to the z-axis, as defined in FIG. 11B. It should be noted that in this configuration, the optical system 1130 is used for both illuminating the SLM 1140 and projecting an image onto the internal coupling optical element 1160. Thus, the optical system 1130 functions as a projection optical system that disperses (e.g., uniformly) the light from the light source 1110, and can further act as an imaging optical system that provides the image of the SLM 1140 and / or the image formed by the SLM 1140 into the eye. The system 1100A in FIGS. 11A / B may be more compact than the system 1000 in FIG. 10 in some instances. In some cases, not employing the PBS 1020 shown in FIG. 10 may potentially reduce the cost and / or size of the present system. Additionally, by not using the PBS 1020, the system may become more symmetric and easier to design by shortening the back focal length of the optical system 1130.

[0192] As referenced above, alternative configurations are also conceivable. Referring to FIG. 11C, for example, in some designs, the system 1100C may be configured to pass light having a polarization that is not rotated by the SLM 1140. In one implementation, for example, the SLM 1140 may be a liquid crystal (LC)-based SLM and may include a vertically aligned (VA) liquid crystal on silicon (LCoS). The SLM 1140 may have a first pixel in a first state that does not rotate polarization and a second pixel in a second state that rotates polarization. In the configuration illustrated in FIG. 11C, a single common analyzer / polarizer 1155 is utilized. This analyzer 1155 may transmit light of a first polarization (e.g., s-polarization) and attenuate or reduce the transmission of a second polarization (e.g., p-polarization). Thus, light (e.g., s-polarization) incident on the first pixel in the first state that does not rotate the polarization orientation is reflected from the SLM 1140 and passes through the analyzer 1155 into the waveguide 1120. Conversely, light (e.g., s-polarization) incident on the second pixel in the second state that rotates the polarization orientation is reflected from the SLM 1140 and is attenuated, reduced, or not passed through the analyzer 1155 into the waveguide 1120. This configuration thereby enables the polarizer 1115 and analyzer 1150 shown in FIG. 11A to be incorporated into a shared optical element, namely, the analyzer 1155 shown in FIG. 11C, thereby potentially simplifying the system 1100 of FIGS. 11A / B by reducing the number of optical components. The analyzer 1155 may be disposed between the waveguide 1120 and the optical system 1130. In other implementations, separate analyzer / polarizers and analyzers / polarizers may be used as shown in the system 1100 of FIGS. 11A / B. FIGS. 11A and 11B illustrate a polarizer 1115 between the light source 1110 and the waveguide 1120 and an analyzer 1140 between the optical system 1130 and the waveguide 1120.

[0193] Various other configurations may be employed to utilize the optical system 1130 for both illumination of the SLM 1140 and imaging of the image formed by the SLM 1140. For example, FIGS. 11A-11C show a single waveguide 1120, but one or more waveguides such as a stack of waveguides (possibly different waveguides for different colors of light) may be used. FIG. 12A illustrates, for example, a cross-sectional side view of an exemplary system 1200A including a stack 1205 including waveguides 1120, 1122, 1124, each including internal coupling optical elements 1260, 1262, 1264. The waveguides 1120, 1122, 1124 may each be configured to output light of one or more different wavelengths or one or more ranges of different wavelengths. The stack 1205 may be substantially similar to stacks 260 and 660 (FIGS. 6 and 9A), and the illustrated waveguides 1120, 1122, 1124 of the stack 1205 may correspond to portions of waveguides 670, 680, 690, however, the stack 1205 and the waveguides 1120, 1122, 1124 are not necessarily so limited. As illustrated in FIG. 12A, the internal coupling optical elements 1260, 1262, 1264 may be associated with, included in, or on the waveguides 1120, 1122, 1124, respectively. The internal coupling optical elements 1260, 1262, 1264 may be color selective and may primarily deflect or redirect a certain wavelength into the corresponding waveguides 1120, 1122, 1124 as guided therein. As illustrated, since the internal coupling optical elements 1260, 1262, 1264 are color selective, the internal coupling optical elements 1260, 1262, 1264 need not be laterally displaced and may be stacked over each other. Wavelength multiplexing may be employed to couple a particular color into the corresponding waveguide. For example, a red internal coupling optical element may internally couple red light into the waveguide designated for propagating red light while not internally coupling blue or green light, which is instead coupled into other waveguides by other blue and green selective waveguides, respectively.

[0194] In some implementations, light source 1110 may be a multi - color light source capable of emitting different colored light at different times. For example, light source 1110 may emit red, green, and blue (RGB) light. In a first time period, it may emit red and amounts of green and blue below a negligible amount. In a second time period, it may emit green and amounts of red and blue below a negligible amount. In a third time period, it may be configured to emit blue and amounts of red and green below a negligible amount. These cycles can be repeated, and SLM 1140 can be coordinated to produce pixel states of a suitable pattern for a particular color (red, green, or blue) and provide appropriate image color components for a given image frame. Different waveguides 1120, 1122, 1124 of stack 1205 may each be configured to output light with different individual colors. For example, as depicted in FIG. 12A, waveguides 1120, 1122, 1124 may each be configured to output blue, green, and red light, respectively. Of course, other colors are also possible. For example, light source 1110 may emit other colors, and color - selective internal - coupling optical elements 1260, 1262, 1264, external - coupling optical elements, etc. can be configured for such other colors. Additionally, the individual red, green, and blue emitters can be positioned close enough to function effectively as a single - pupil light source. The red, green, and blue emitters may be combined with lenses and dichroic splitters to form a single red, green, and blue pupil source. The multiplexing of a single pupil may be extended beyond or in addition to color selectivity and may include the use of polarization - dependent gratings and polarization switching. These color or polarization gratings can also be used in combination with multiple display pupils to increase the number of addressable layers.

[0195] The different internal coupling optical elements 1260, 1262, 1264 within different waveguides 1120, 1122, 1124 are laterally displaced relative to each other and can be arranged across and / or beneath each other and laterally aligned (e.g., in the x and z directions shown in FIG. 12A), as opposed to being misaligned. Thus, in some implementations, for example, light of a first color can be coupled into waveguide 1120 by internal coupling optical element 1260 such that it is guided therein, light of a second color different from the first color can pass through internal coupling optical element 1260 to the next internal coupling optical element 1262 and can be coupled into waveguide 1122 by internal coupling optical element 1262 such that it is guided therein. Light of a third color different from the first and second colors can pass through internal coupling optical elements 1260 and 1262 to internal coupling optical element 1264 and can be coupled into waveguide 1124 such that it is guided therein. Additionally, the internal coupling optical elements 1260, 1262, 1264 may be polarization selective. For example, the different internal coupling optical elements 1260, 1262, 1264 can be configured such that light of a certain polarization is either coupled into the waveguide by the corresponding polarization selective internal coupling optical elements 1260, 1262, 1264 or passes through the internal coupling optical elements 1260, 1262, 1264.

[0196] Depending on the configuration, SLM 1140 may include a polarization-based SLM that modulates polarization. System 1200A can include, for example, a polarizer and / or analyzer that modulates the light input into stack 1205 on a pixel-by-pixel basis depending on the state of an individual pixel (e.g., whether the pixel rotates the polarization orientation). Various aspects of such systems that employ a polarization-based SLM have been discussed above, and any one of such features may be employed in combination with any other feature described herein. However, other designs are still considered possible.

[0197] For example, a deflection-based SLM1140 may be employed. For example, the SLM1140 may include one or more movable optical elements, such as a movable mirror, that can reflect and / or deflect light along different directions according to the state of the optical element. The SLM1140 may include one or more pixels that include such optical elements, such as micromirrors or reflectors. The SLM1140 may, for example, incorporate digital light processing (DLPTM) technology, which uses a digital micromirror device (DMD). An example of the system 1200B that uses such a deflection-based SLM1140 is shown in FIG. 12B. The system 1200B includes a deflection-based SLM1140 and an optical dump 1250. The optical dump 1250 may include an absorbing material or a structure configured to absorb light. The deflection-based SLM1140 may include one or more micro-movable mirrors that can be selectively tilted to deflect light in different directions. For example, the deflection-based SLM1140 may be configured to deflect light from the light source 1110 incident thereon to the internal coupling optical elements 1260, 1262, 1264 when a given pixel is in the bright state. As discussed above, this light will thus be coupled into one of the individual waveguides 1120, 1122, 1124 by one of the internal coupling optical elements 1260, 1262, 1264 and directed to the eye 210, for example, according to the color of the light. Conversely, when a given pixel is in the dark state, the light from the light source 1110 can be deflected to the optical dump 1250, and the light will not be coupled into one of the individual waveguides 1120, 1122, 1124 by one of the internal coupling optical elements 1260, 1262, 1264 and directed to the eye 210. Instead, the light can be absorbed by the absorbing material that makes up the optical dump 1250. In some implementations, the analyzer 1150 may be a polarizer (e.g., a "clean-up" polarizer) used to eliminate unwanted reflections from the internal coupling optical elements 1260, 1262, 1264. This polarizer may be useful because the optical system 1130 may include plastic optical elements that have birefringence and can modify polarization.A "cleanup" polarizer can attenuate or remove unwanted polarized light (e.g., reflected light) so that it is not directed onto waveguides 1120, 1122, 1124. Other types of optical adjustment elements may also be disposed, such as between the optical system 1130 and the waveguides 1120, 1122, 1124, or between the SLM 1140 and the waveguides 1120, 1122, 1124. For example, such optical adjustment elements may also include a circular polarizer (i.e., a retarder such as a linear polarizer and a quarter-wave plate). The circular polarizer can again reduce the amount of reflection from the waveguides 1120, 1122, 1124 or the internal coupling optical elements 1260, 1262, 1264 that is incident on and coupled therein. The reflected light can be circularly polarized and can carry the opposite circular polarization of the incident light (e.g., depending on the reflection, right-handed circularly polarized light is converted to left-handed circular polarization, or vice versa). The retarder in the circular polarizer may convert the circular polarization to linear polarization that is attenuated, e.g., absorbed, by a linear polarizer in the circular polarizer, such as the orthogonal polarization of the polarizer. The cleanup polarizer may be used in combination with a polarization-independent modulator such as a DMD. As described above, the cleanup polarizer can be useful for suppressing reflection and / or improving the coupling of light into the internal coupling optical elements 1260, 1262, 1264 with an optimal polarization state.

[0198] FIG. 12B illustrates a side or cross-sectional view of such a system 1200B, while FIG. 12C shows a top view of a side arrangement of the internal coupling optical element 1264, the optical dump 1250, and the light source 1110. The SLM 1140 is configured to reflect, deflect, and / or direct light from the light source 1110 to either the internal coupling optical element 1264 (and the other internal coupling optical elements 1260, 1262) or a lateral location of the optical dump 1250, depending on the state of a particular pixel.

[0199] In one design, the optical damper 1250 may include an energy recovery system. The optical damper 1250 may include, for example, an optical energy conversion element configured to convert optical energy into electrical energy. The optical energy conversion element may include, for example, a solar cell. The optical energy conversion element may include, for example, a photovoltaic detector that produces an electrical output when light is incident thereon. The optical energy conversion element may be electrically connected to a conductive wire for directing the electrical output to an electrical component, for example, to provide power to the system 1200B and / or potentially to charge one or more batteries.

[0200] A laterally displaced non-color-selective or broadband or multi-color internal coupling optical element may be used in a design. FIG. 13A is a perspective view of a system 1300 including a stack 1305 including, for example, waveguides. The stack 1305 may be substantially similar to the stack 1205, referenced in FIG. 12A. Each waveguide in the stack 1305 may include internal coupling optical elements 1360, 1362, 1364, however, in contrast to the design shown in FIG. 12A, the internal coupling optical elements 1360, 1362, 1364 are laterally displaced relative to each other. As shown in FIGS. 13A, 13B, and 13C, light sources 1110, 1112, 1114 are also laterally displaced relative to each other and are arranged to direct light through the optical system 1130, reflect the light from the SLM 1140, and pass the reflected light back through the optical system 1130 to direct the light to individual internal coupling optical elements 1360, 1362, 1364. The system 1300 of FIG. 13B depicts the light source 1114 as being located behind the light source 1110 and thus not shown in FIG. 13B. The light sources 1110, 1112, 1114 may each correspond to the internal coupling optical elements 1360, 1362, 1634. In one design, for example, the light sources 1110, 1112, 1114 and the corresponding internal coupling optical elements 1360, 1362, 1364 are generally arranged equidistantly (symmetrically about it) along a common (optical) axis from the center of the optical system 1130. The common (optical) axis may intersect the center of the optical system 1130. In one design, for example, the light sources 1110, 1112, 1114 and the corresponding internal coupling optical elements 1360, 1362, 1364 are not arranged equidistantly (symmetrically about it) along a common (optical) axis from the center of the optical system 1130.

[0201] The internal coupling optical elements 1360, 1362, 1364 may be configured to couple light of a plurality of colors into their respective waveguides. Thus, these internal coupling optical elements 1360, 1362, 1364 may be referred to herein as broadband, multi-color, or non-color-selective internal coupling optical elements 1360, 1362, 1364. For example, in some cases, one of each of these internal coupling optical elements 1360, 1362, 1364 is configured to internally couple red, green, and blue light into the associated waveguide in which the internal coupling optical elements 1360, 1362, 1364 are included, and such colored light is induced within the waveguide by TIR. Such broadband internal coupling optical elements 1360, 1362, 1364 operate, for example, across a wide range of wavelengths within the visible range, or may select a wavelength or wavelength region width, for example, across the visible range. Thus, such broadband or multi-color or non-color-selective internal coupling optical elements 1360, 1362, 1364 may be configured to redirect light of various different colors (e.g., red, green, and blue) into the waveguide so as to be induced therein by TIR. Red, green, blue (RGB) are referred to herein in connection with, among other things, light sources, internal coupling optical elements, waveguides, etc., but other colors or color systems may also be used in addition to, or alternatively, for example, but not limited to, magenta, cyan, yellow (CMY), etc.

[0202] As shown in FIG. 13A, light sources 1110, 1112, 1114 are shown above the top waveguide and are displaced relative to each other (e.g., in the x and z directions). Similarly, three internal coupling optical elements 1360, 1362, 1364 are shown on three individual waveguides and are displaced relative to each other (e.g., in the x, y, and z directions). FIG. 13B is a side view of the system 1300 shown in FIG. 13A, showing some of the internal coupling optical elements 1360, 1362, 1364 that are laterally spatially displaced relative to each other (e.g., in the x and z directions) and some of the light sources 1110, 1112, 1114 that are laterally displaced relative to each other (e.g., in the x and z directions). FIG. 13B also shows the optical system 1130 and the SLM 1140.

[0203] FIG. 13C is a top view of the augmented reality display system shown in FIGS. 13A and 13B, showing the internal coupling optical elements 1360, 1362, 1364 and the associated light sources 1110, 1112, 1114. In this design, the internal coupling optical elements 1360, 1362, 1364 and the associated light sources 1110, 1112, 1114 are arranged in a ring pattern centered on the center point of a common (optical) axis. As shown, the light sources 1110, 1112, 1114 and the corresponding internal coupling optical elements 1360, 1362, 1364 are generally equidistantly arranged centered on the center point of the common (optical) axis, however, this is not necessarily required. In some designs, this center point may correspond to the center of the optical system 1130 along the common (optical) axis that intersects the center of the optical system 1130 and / or a location along the optical axis of the optical system 1130. Also, as a result, the achromatic internal coupling optical elements 1360, 1362, 1364 and the light sources 1110, 1112, 1114 are laterally displaced relative to each other (e.g., in the x and z directions).

[0204] Other arrangements with side settings are also conceivable. FIGS. 14A-14C illustrate an alternative configuration of system 1400 including stack 1405 including waveguides, and internal coupling optical elements 1360, 1362, 1364 and light sources 1110, 1112, 1114 are displaced laterally relative to each other. FIG. 14A is a side view of system 1400 shown in FIG. 14A showing laterally displaced internal coupling optical elements 1360, 1362, 1364 and light sources 1110, 1112, 1114, while FIG. 14B is a top view. FIG. 14C is an orthogonal side view of system 1400 shown in FIGS. 14A and 14B.

[0205] The side views of FIGS. 14A and 14C show how the internal coupling optical elements 1360, 1362, 1364 are arranged on separate waveguides within stack 1405 such that light can be coupled into the corresponding waveguides by the individually laterally displaced internal coupling optical elements 1360, 1362, 1364. The internal coupling optical elements 1360, 1362, 1364 are shown in FIGS. 14A and 14C as being disposed within the upper major surface of the waveguides. However, the internal coupling optical elements 1360, 1362, 1364 can alternatively be disposed on the lower major surface of the individual waveguides or within the volume of the waveguides. Various configurations are also conceivable.

[0206] As shown in the top view of FIG. 14B, the internal coupling optical elements 1360, 1362, 1364 are arranged in columns that are laterally displaced relative to each other along the z direction rather than along the x direction. Similarly, the light sources 1110, 1112, 1114 are also arranged in columns that are laterally displaced relative to each other along the z direction rather than along the x direction. The internal coupling optical elements 1360, 1362, 1364 are laterally displaced in the x direction relative to the light sources 1110, 1112, 1114.

[0207] Still other configurations are also conceivable as possibilities. FIG. 15 is a top view of system 1500 showing an alternative configuration of light sources 1110, 1112, 1114 and internal coupling optical elements 1360, 1362, 1364. In contrast to having all of the light sources 1110, 1112, 1114 generally on one side (e.g., in a ring pattern) and all of the internal coupling optical elements 1360, 1362, 1364 generally on one side (i.e., the opposite side) as in FIG. 13C, the light sources 1110, 1112, 1114 and the internal coupling optical elements 1360, 1362, 1364 are scattered or alternating along the circumference of the ring pattern.

[0208] However, in some implementations, the internal coupling optical elements 1360, 1362, 1364 and one or more associated light sources 1110, 1112, 1114 are also arranged in a ring pattern about a central point. As a result, the light sources 1110, 1112, 1114 and the corresponding internal coupling optical elements 1360, 1362, 1364 may be arranged generally equidistant from the center. In some designs, this center may correspond to the center of the optical system 1130 along a common central axis that intersects the center of the optical system 1130 and / or a location along the optical axis of the optical system. Thus, light from the first light source 1110 may be coupled through the optical system 1130 into the internal coupling optical element 1360, across the center or central axis or optical axis of the optical system 1130 (as seen from the top view of FIG. 15). Similarly, light from the second light source 1112 may be coupled through the optical system 1130 into the internal coupling optical element 1362, across the center or central axis or optical axis of the optical system 1130. Similarly, light from the third light source 1114 may be coupled through the optical system 1130 into the internal coupling optical element 1364, across the center or central axis or optical axis of the optical system 1130. Also, as a result, the achromatic internal coupling optical elements 1360, 1362, 1364 and the light sources 1110, 1112, 1114 are displaced laterally relative to each other (e.g., in the x and z directions). The optical system 1130 may be designed such that the focus is more within the stack 1405, such that the sub-pupil location and the internal coupling optical elements 1360, 1362, 1364 are closer in the y-direction. In this configuration, the internal coupling optical elements 1360, 1362, 1364 may be smaller since they are closer to the focus of the optical system 1130. The light source 1110 is on the user side of the stack 1405 (e.g., similar to FIGS. 17 and 18), and thus, the distance or optical path between the light source 1110 and the optical system 1130 may be reduced.

[0209] In various implementations such as those shown in FIGS. 12A - 15 above, stacks (e.g., stack 1205 including waveguide 1120, 1122, 1124, stack 1305 including waveguide (not labeled), and stack 1405 including waveguide (not labeled)) including a plurality of waveguides may be included to handle different colors (e.g., red, green, and blue). Different waveguides may be for different colors. Similarly, a plurality of stacks may be included to provide different optical properties to the light externally coupled from individual stacks. For example, the waveguides 1120, 1122, 1124 of stack 1205 in FIGS. 12A - 12B may be configured to output light having an optical property (e.g., refractive power to provide a particular wavefront shape) associated with apparent depth such that light appears to emanate therefrom. For example, wavefronts having different amounts of divergence, convergence, or collimation may appear as if projected from different distances from the eye 210. Thus, a plurality of stacks may be included, and different stacks may be configured such that the light externally coupled by an external coupling optical element has different amounts of convergence, divergence, or collimation and thus appears to originate from different depths. In some designs, different stacks may include different lenses such as diffractive lenses or other diffractive optical elements to provide different amounts of refractive power to different stacks. As a result, different stacks produce different amounts of convergence, divergence, or collimation, and thus the light from different stacks will appear to be associated with different depth planes or objects at different distances from the eye 210.

[0210] FIG. 16A is a side view of system 1600, including stacks 1605, 1610, 1620. As shown in FIG. 16A, system 1600 includes three stacks 1605, 1610, 1620, however, this is not necessarily the case. The system may be devised with fewer or more stacks. Stacks 1605, 1610, and 1620 each include one or more (e.g., three) waveguides. FIG. 16A also shows groups 1630, 1640, 1650 of internal coupling optical elements. The first group 1630 is associated with the first stack 1605, the second group 1640 is associated with the second stack 1610, and the third group 1650 is associated with the third stack 1620. Groups 1630, 1640, 1650 are laterally displaced relative to each other. Groups 1630, 1640, 1650 each include color-selective internal coupling optical elements configured to internally couple different individual colors, substantially similar to internal coupling optical elements 1260, 1262, 1264 of FIG. 12A. As shown in FIG. 16A, the internal coupling optical elements within each of groups 1630, 1640, 1650 are not laterally displaced relative to each other, however, this is not necessarily the case. The system may be devised such that the internal coupling optical elements within a group are laterally displaced relative to each other. System 1600 may be configured such that the light externally coupled from each of stacks 1605, 1610, 1620 has different amounts of refractive power. For example, the waveguides within a stack may have an external coupling optical element or diffractive lens having a given refractive power. The refractive powers for different stacks 1605, 1610, 1615 may differ such that light from one stack appears at a different depth than light from another stack. The refractive power of one stack may be caused, for example, to collimate the light from that stack, while the refractive power of another stack may be caused to diverge the light therefrom. The diverging light may appear to originate from a nearby object from the eye 210, while the collimated light may appear to originate from an object at a distance.Thus, the light externally coupled from the first stack 1605, the second stack 1610, and the third stack 1620 has at least one of different amounts of convergence, divergence, and collimation, and can thus appear to originate from different depths. In some implementations, the light externally coupled from one of the stacks can be collimated, while the light externally coupled by different stacks can diverge. The light externally coupled from one of the other stacks also diverges, but can diverge by different amounts.

[0211] As shown in FIG. 16A, the light source 1110 can be arranged with respect to the optical system 1130 and the SLM 1140 and direct light into the group 1630 of internally coupled optical elements, the light source 1112 can be arranged with respect to the optical system 1130 and the SLM 1140 and direct light into the group 1640 of internally coupled optical elements, and the light source 1114 can be arranged with respect to the optical system 1130 and the SLM 1140 and direct light into the group 1650 of internally coupled optical elements. The light sources 1110, 1112, 1114 can be configured to emit different colors of light at different times. Similarly, different individual colors of light can be coupled into different waveguides within the stack as a result of color-selective internally coupled optical elements in the manner described above. For example, if blue light is emitted from the second light source 1112, the optical system 1130 and the SLM 1140 will direct the blue light into the second group 1640 of internally coupled optical elements. The light passes through a first red internally coupled optical element and a second green internally coupled optical element within the second group 1640 and can be redirected into the third waveguide within the second stack 1610 by a third blue internally coupled optical element within the second group 1640. The waveguides within the second stack 1610 can include external coupling optical elements or other optical elements having a refractive power (e.g., a diffractive lens) that provides a beam associated with a particular depth plane or object distance associated with the second stack 1610 to the eye 210.

[0212] Figure 16B is a top view of the system 1600 in Figure 16A. Different groups 1630, 1640, 1650 of internally coupled optical elements are shown to be laterally displaced relative to each other (e.g., in the x direction). Similarly, light sources 1110, 1112, 1114 are shown to be laterally displaced relative to each other (e.g., in the x direction).

[0213] Various different variations in the aforementioned system are also conceivable. For example, the location of the light source 1110 with respect to the waveguide and the optical system 1130 can be different. FIG. 17 is, for example, a side view of the system 1700 having the light source 1110 in a location with respect to a waveguide 1720 and an optical system 1130 different from that shown in FIGS. 11 - 16B. Additionally, FIG. 17 shows a design with a waveguide 1720 that is divided into a first portion 1720a and a second portion 1720b. The waveguide 1720 may further include a reflector 1730 configured to couple light induced within the first portion 1720a proximal to the light source 1110 from the first portion 1720a out into the optical system 1130 and towards the SLM 1140. Additionally, or alternatively, the system 1700 may include a diffractive external coupling optical element for externally coupling light within the first portion 1720a of the waveguide 1720 into the optical system 1130 and towards the SLM 1140. This reflector 1730 may include an isolator that is opaque and reduces crosstalk between the first portion 1720a and the second portion 1720b. The waveguide 1720 has a first side 1721 and a second side 1723 opposite the first side 1721, and the optical system 1130 and the SLM 1140 are disposed on the first side 1721 such that light from the SLM 1140 is directed onto the first side 1721. In this embodiment, the light source 1110 is disposed on the first side 1721 of the waveguide 1720 such that light from the light source 1110 is incident on the first side 1721 prior to passing through the optical system 1130 to the SLM 1140. The system 1700 may further include an internal coupling optical element 1710 disposed on or within the first portion 1720a. The internal coupling optical element 1710 may be configured to receive light from the light source 1110 and couple the light into the first portion 1720a. The internal coupling optical element 1710 may include a diffractive optical element or a reflector configured to redirect light incident thereon at an angle such that it is guided therein by TIR into the first portion 1720a.

[0214] The reflector 1730 may be configured to direct light induced within the first portion 1720a out of the first portion 1720a and toward the optical system 1130 and the SLM 1140. (As discussed above, in some implementations, diffractive optical elements may additionally or alternatively be used to direct light within the first portion 1720a out of the first portion 1720a and toward the optical system 1130 and the SLM 1140.) Thus, the reflector 1730 may be a mirror, a reflective grating, one or more coatings that reflect the light of the waveguide 1720 toward the SLM 1140. By the reflector 1730, the light emitted from the first portion 1720a passes through the optical system 1130, is incident on the SLM 1140, passes through the optical system 1130 again, and is incident on the second portion 1720b. As described above, the light reflected from the SLM 1140 and transmitted through the optical system 1130 may be incident on the internal coupling optical element 1160 and redirect the light induced within the second portion 1720b. The light induced within the second portion 1720b may be externally coupled therefrom by an external coupling optical element 1180 (not shown) and directed toward the eye 210.

[0215] As discussed above, the reflector 1730 may be an isolator that reduces crosstalk between the first portion 1720a and the second portion 1720b. The reflector 1730 may include an opaque and / or reflective surface. The reflector 1730 may be disposed within the waveguide 1720 and, in some cases, may define the sides of the first portion 1720a and the second portion 1720b.

[0216] Instead of having first and second portions 1720a, 1720b of waveguide 1720, separate waveguides may be used. FIG. 18 is a side view of a system 1800 that includes a first waveguide 1822 that receives light from a light source 1110 and directs the light induced therein toward an optical system 1130 and toward an SLM 1140. The system 1800 additionally includes a second waveguide 1820 that receives light from the SLM 1140 after the light has passed back through the optical system 1130. The first waveguide 1822 each includes internal and external coupling optical elements 1730a, 1730b. These internal and external coupling optical elements 1730a, 1730b may include reflective surfaces that are oriented to internally and externally couple light into and out of the waveguide 1822. The internal coupling optical element 1730a may include, for example, a reflective surface that is arranged to receive light from the light source 1110 and is oriented (e.g., tilted) at an angle such that the light is directed into the waveguide 1822 where it is induced by TIR. The external coupling optical element 1730b may include, for example, a reflective surface that is oriented (e.g., tilted) at an angle such that the light induced within the waveguide 1822 is directed out of the waveguide 1822. The external coupling optical element 1730b may be positioned such that the light redirected out of the waveguide 1822 is directed into the optical system 1130, reflected from the SLM 1140, passes back through the optical system 1130, and is incident on the internal coupling optical element 1730c of the second waveguide 1820.

[0217] The internal coupling optical element 1730c within the second waveguide 1820 may include a reflective surface that is positioned and oriented (e.g., tilted) to receive light incident thereon from the SLM 1140 and redirect it to be guided within the second waveguide 1820 by TIR. FIG. 18 illustrates the optical system 1130 and the light source 1110 disposed on the same side of the waveguides 1820, 1822. The system 1800 may further include an isolator that reduces crosstalk between the waveguide 1822 and the waveguide 1820. The isolator may include an opaque and / or reflective surface. The isolator may be disposed within or on at least one of the waveguides 1820, 1822.

[0218] The various designs such as those discussed above can include additional features or components. FIG. 19 shows, for example, a side view of a system 1900 that includes variable focus optical elements (or adaptive optical elements) 1910, 1920. The variable focus optical elements 1910, 1920 may include optical elements configured to be modified to provide a variable refractive power. The variable focus optical elements 1910, 1920 may include a plurality of states such as a first state and a second state, and in the first state, the variable focus optical elements 1910, 1920 have a refractive power different from when in the second state. For example, the variable focus optical elements 1910, 1920 may have a negative refractive power in the first state and a zero refractive power in the second state. In some implementations, the variable focus optical elements 1910, 1920 have a positive refractive power in the first state and a zero refractive power in the second state. In some implementations, the variable focus optical elements 1910, 1920 have a first negative or positive refractive power in the first state and a second different negative or positive refractive power in the second state. Some adaptive optical elements or variable focus optical elements 1910, 1920 may have more than two states and possibly provide a continuous distribution of refractive power.

[0219] The variable focus optical elements 1910, 1920 include a lens (e.g., a variable lens) and may be transmissive. The transmissive or transparent adaptive optical elements or variable focus optical elements 1910, 1920 are shown in FIG. 7. The variable focus optical elements 1910, 1920 may include a liquid lens (e.g., a movable membrane and / or electro-wetting). The variable focus lens may also include a liquid crystal lens such as a switchable liquid crystal lens such as a switchable liquid crystal polarization lens, which may include, for example, a diffractive lens. An Alverez lens may also be used. Other types of variable focus optical elements 1910, 1920 may also potentially be employed. Examples of variable focus optical elements can be found in U.S. Patent Application No. 62 / 518,539, filed on Jun. 12, 2017, entitled "AUGMENTED REALITY DISPLY HAVING MULTI-ELEMENT ADAPTIVE LENS FOR CHANGING DEPTH PLANES" (incorporated herein by reference in its entirety). The variable focus optical elements 1910, 1920 may have an electrical input that receives an electrical signal to control the amount of refractive power presented by the variable focus optical elements 1910, 1920. The variable focus optical elements 1910, 1920 may have positive and / or negative refractive power. In addition to variable focus elements (e.g., polarization switches, geometric phase (GP) lenses, fluid lenses, and equivalents), the variable focus optical elements 1910, 1920 may include fixed lenses (e.g., diffractive lenses, refractive lenses, and equivalents) and may generate a desired depth plane in the light field.

[0220] The first variable focus optical element 1910 may be disposed between the stack 1905 and the eye 210. The stack 1905 may include different waveguides for different colors, as discussed above. The first variable optical element 1910 may be configured to introduce different amounts of refractive power, negative and / or positive refractive power. The variable refractive power may be used to vary the divergence and / or collimation of the light coupled out from the stack 1905 and appear to vary the depth such that the virtual object projected into the eye 210 by the system 1900 is located. Thus, a 4-dimensional (4D) light field may be created.

[0221] The second variable focus optical element 1920 is on the opposite side of the first variable focus optical element 1920 of the stack 1905. The second variable focus optical element 1920 can thus compensate for the effect of the first optical element 1910 on the light received from the front world 510 of the system 1900 and the eye 210. Thus, the world view may or may not be effectively modified as desired.

[0222] System 1900 can further include a static or variable prescription or corrective lens 1930. Such a lens 1930 may provide refractive correction for the eye 210. Additionally, if the prescription lens 1930 is a variable lens, it may provide different refractive corrections for multiple users. Variable focus lenses are discussed above. The eye 210 may have, for example, myopia, hyperopia, and / or astigmatism. The lens 1930 may have a prescription (e.g., refractive power) to reduce the refractive error of the eye 210. The lens 1930 may be spherical and / or cylindrical and may be positive or negative. The lens 1930 may be disposed between the stack 1905 and the eye 210 such that light from both the world 510 and the stack 1905 undergoes the correction provided by the lens 1930. In some implementations, the lens 1930 may be disposed between the eye 210 and the first variable focus optical element 1910. Other locations for the lens 1930 are also possible. In some embodiments, the prescription lens is variable and may allow for the implementation of multiple user prescriptions.

[0223] In some designs, the system 1900 may include an adjustable dimming device 1940. In some implementations, the adjustable dimming device 1940 may be disposed on the side of the stack of the waveguide 1900 opposite the eye 210 (e.g., the world side). Thus, the adjustable dimming device 1940 may be disposed between the stack of the waveguide 1900 and the world 510. The adjustable dimming device 1940 may include an optical element that provides variable attenuation of the light transmitted therethrough. The adjustable dimming device 1940 may include an electrical input for controlling the level of attenuation. In some cases, the adjustable dimming device 1940 is configured to increase attenuation when the eye 210 is exposed to bright light, such as when the user goes outdoors. Thus, the system 1900 may include a light sensor for sensing the brightness of the ambient light and control electronics for driving the adjustable dimming device 1940 and varying the attenuation based on the light level sensed by the light sensor.

[0224] Different types of adjustable dimmers 1940 may be employed. Such adjustable dimmers 1940 may include variable liquid crystal switches with polarizers, electrochromic materials, photochromic materials, and the like. The adjustable dimmers 1940 may be configured to adjust the amount of light incident on and / or transmitted through the stack 1905 from the world 510. The adjustable dimmers 1940 can, in some cases, be used to reduce the amount of ambient light passing through the waveguide stack 1900 to the eye 210, which otherwise can provide glare and reduce the ability of the user to perceive the virtual object / image projected into the eye 210 from the stack 1905. Such adjustable dimmers 1940 can reduce the incident bright ambient light so as not to wash out the image projected into the eye 210. The contrast of the virtual object / image presented to the eye 210 can thus be increased using the adjustable dimmers 1940. In contrast, when the ambient light is low, the adjustable dimmers 1940 may be adjusted to reduce attenuation so that objects within the world 510 in front of the user 210 can be seen more easily by the eye 210. The dimming or attenuation may be present across the system or may be localized to one or more parts of the system. For example, a plurality of localized portions may be dimmed or set to attenuate light from the world 510 in front of the user 210. These localized portions can be separated from each other by portions without such increased dimming or attenuation. In some cases, only one portion is dimmed or results in increased attenuation for the other parts of the eyepiece. Other components may also be added in different designs. Also, the arrangement of the components can be different. Similarly, one or more components may be excluded from the system.

[0225] An example of another configuration is shown in FIG. 20A. FIG. 20A shows a side view of system 2000 including a color filter array 2030 that includes laterally displaced internal coupling optical elements 1360, 1362, 1364 on different waveguides and laterally displaced color filters 2040, 2042, 2044 that align with the individual internal coupling optical elements 1360, 1362, 1364. The color filter array 2030 may be disposed on a side proximate to the eye 210 of the stack 2005 and the optical system 1130. The color filter array 2030 may be between the stack 2005 and the optical system 1130. The color filter array 2030 may be disposed within or on a cover glass 2050 that is located between the stack 2005 and the optical system 1130. The color filter array 2030 may include one or more different color filters 2040, 2042, 2044 such as a red color filter, a green color filter, and a blue color filter that are laterally disposed relative to each other. System 2000 includes light sources 1110, 1112, 1114 that are laterally displaced relative to each other. These light sources 1110, 1112, 1114 may include light sources of different colors such as red, green, and blue light sources. The color filters 2040, 2042, 2044 may be transmissive or transparent filters. In some implementations, the color filters 2040, 2042, 2044 include absorption filters, however, the color filters 2040, 2042, 2044 may also include reflective filters. The color filters 2040, 2042, 2044 within the color filter array 2030 may be separated and / or surrounded by a mask such as an opaque mask that will reduce the propagation of stray light. The filters within the color filter array 2030 are used to reduce or eliminate unwanted reflections within the system such as from the waveguides and / or the internal coupling optical elements 1360, 1362, 1364 so that they do not re-enter the waveguides used for different colors through the internal coupling optical elements 1360, 1362, 1364 for different colors.Examples of color filter arrays can be found in U.S. Patent Application No. 15 / 683412, filed on August 22, 2017, entitled "PROJECTOR ARCHITECTURE INCORPORATING ARTIFACT MITIGATION" (incorporated herein by reference in its entirety), and U.S. Patent Application No. 62 / 592607, filed on November 30, 2017, entitled "PROJECTOR ARCHITECTURE INCORPORATING ARTIFACT MITIGATION" (incorporated herein by reference in its entirety). The mask may be a black mask and may include an absorbing material for reducing the propagation and reflection of stray light. The light sources 1110, 1112, 1114 may be arranged with respect to the optical system 1130 and the SLM 1140 and may internally couple light to corresponding color filters 2040, 2042, 2044 within the color filter array 2030. For example, the color filter array 2030 may include first, second, and third (e.g., red, green, and blue) color filters 2040, 2042, 2044 arranged to receive light from the first, second, and third light sources 1110, 1112, 1114, respectively. The first, second, and third (e.g., red, green, and blue) color filters 2040, 2042, 2044 may be aligned with individual internal coupling optical elements 1360, 1362, 1364 (e.g., in the x and z directions). Thus, light from the first light source 1110 is directed through the first color filter 2040 to the first internal coupling optical element 1360, light from the second light source 1112 is directed through the second color filter 2042 to the second internal coupling optical element 1362, and light from the third light source 1114 is directed through the third color filter 2044 to the third internal coupling optical element 1364. In some implementations, the internal coupling optical elements 1360, 1362, 1364 may be color specific. For example, the first and second internal coupling optical elements 1360, 1362 may be configured to couple light of individual first and second colors into the first and second waveguides, respectively.Similarly, the first, second, and third internal coupling optical elements 1360, 1362, 1364 may be configured to couple light of the individual first, second, and third colors into the first, second, and third waveguides, respectively. The first internal coupling optical element 1360 may be configured to couple light of the first color into the first waveguide more than the light of the second color (or the third color). The second internal coupling optical element 1362 may be configured to couple light of the second color into the second waveguide more than the light of the first color (or the third color). The third internal coupling optical element 1364 may be configured to couple light of the third color into the second waveguide more than the light of the first color or the second color. In other configurations, the internal coupling optical elements 1360, 1362, 1364 may be broadband. For example, the first internal coupling optical element 1360 may be configured to couple light of the first, second, and third colors into the first waveguide. The second internal coupling optical element 1362 may be configured to couple light of the first, second, and third colors into the second waveguide. The third internal coupling optical element 1364 may be configured to couple light of the first, second, and third colors into the third waveguide. However, the plurality of color filters 2040, 2042, 2044 may be color-specific to selectively transmit light of a specific color. For example, the first color filter 2040 may transmit the first color more than the second color (and the third color). The second color filter 2042 may transmit the second color more than the first color (and the third color). The third color filter 2044 may transmit the third color more than the first color and the second color. Similarly, the first, second, and third color filters 2040, 2042, 2044 may be color filters that selectively transmit the first, second, and third colors, respectively. Therefore, the first, second, and third color filters 2040, 2042, 2044 may be bandpass filters that selectively pass the first, second, and third colors, respectively. In some implementations, the first, second, and third light sources 1110, 1112, 1114 may selectively emit the first, second, and third colors, respectively. For example, the first light source 1110 may emit the first color more than the second color (and the third color).The second light source 2042 may emit a second color rather than the first color (and the third color). The third light source 2044 may transmit a third color rather than the first and second colors. The color filters 2040, 2042, 2044 may reduce the amount of stray light inadvertently directed at certain internal coupling optical elements. In other implementations, one or more of the light sources 1110, 1112, 1114 are broadband light sources. For example, the first light source 1110 may emit the first and second (and possibly the third) colors. The second light source 1112 may also emit the first and second (and possibly the third) colors. The third light source 1114 may also emit the first and second (and possibly the third) colors. Three filters are shown in FIGS. 20A-20G, although more or fewer filters may be included. For example, in some implementations, two (rather than three) filters may be used. Thus, two colors corresponding to the two color filters may be selectively transmitted therethrough by the filters. In some such implementations, two corresponding internal coupling optical elements may be used and aligned with the two filters. In some implementations, the two internal coupling optical elements each selectively couple two colors into two separate waveguides. In some implementations, two light sources may be used instead of three. Other variations of the components and other numbers may also be used. Also, the color filters 2040, 2042, 2044 may or may not be integrated together within a single array.

[0226] As discussed above, the components and their locations and arrangements may vary. For example, while FIG. 20A shows the analyzer 1150 disposed between the optical system 1130 and the stack 1905, the analyzer 1150 may be located in a different position. FIG. 20B shows the analyzer 1150 located between the optical system 1130 and the SLM 1140. In some designs, the analyzer (e.g., polarizer) 1150 may be directly attached to the SLM 1140. For example, the analyzer 1150 may be glued or mechanically coupled to the SLM 1140. For example, the analyzer 1150 may be glued or fixed to the SLM 1140 (e.g., an SLM window) using an adhesive. Thus, while FIG. 20B shows a gap between the analyzer 1150 and the SLM 1140, in some designs, there is no gap between the analyzer 1150 and the SLM 1140. The analyzer 1150 may be mechanically affixed to the SLM 1140 (e.g., using a mechanical fastener), which may or may not include a gap between the analyzer 1150 and the SLM 1140. Birefringence from the optical system 1130 may be cleared by positioning a polarizer directly on the SLM 1140, as described above. In some implementations, the analyzer 1150, located between the optical system 1130 and the incoupling optical elements 1360, 1362, 1364, may also be included to clear the polarization of light outward from the optical system 1130 (e.g., as illustrated by the dashed lines in FIG. 20B). In addition, a retarder (not shown), such as a quarter-wave plate, may be included proximate the SLM 1140, e.g., between the optical system 1130 and the SLM 1140. As used herein, a quarter-wave plate may refer to a quarter-wave retarder, regardless of whether the quarter-wave retarder comprises a plate, film, or other structure for providing a quarter-wave phase difference. In FIG. 20B, for example, a retarder (e.g., a quarter-wave plate) may be disposed between the analyzer 1150 and the SLM 1140. The retarder (e.g., a quarter-wave plate) may be used for distorted light management. For example, the retarder (e.g., a quarter-wave plate) may compensate for variations caused by differences in wavelength and angle of incidence on the SLM 1140, for example.As discussed above, a compensator may be included and may provide more consistent polarization rotation of the SLM 1140 (e.g., 90°) for different angles of incidence and different wavelengths. The compensator may be used to increase the contrast of the display by providing more consistent orthogonal rotation. The compensator may be attached or adhered to the SLM 1140 as described above. For example, glue, cement, or other adhesives may be used. The compensator may also be attached to the SLM 1140 using mechanical fixtures. A gap or no gap may be included between the compensator and the SLM 1140. Other optical conditioning optics may also be included, in addition to, or in place of, and may be adhered to the SLM 1140 as described above with respect to the analyzer 1150 and / or the compensator.

[0227] In some embodiments, a large angular width (e.g., about 70 degrees) may be used. The angular width may refer to, for example, the angle of light incident from the light sources 1110, 1112, 1114 into the optical system 1130, and / or the angle of light exiting from the optical system 1130 into the internal coupling optical elements 1360, 1362, 1364. In these embodiments, a thinner SLM 1140 may be used. For example, if the SLM 1140 is a liquid crystal (LC) SLM (e.g., a liquid crystal on silicon (LCOS) SLM), the LC layer may be made thinner to accommodate the large angular width.

[0228] The double-path optical path difference through the polarizer and analyzer 1150 may need to be half-wave. The polarizer may be between the optical system 1130 and the analyzer 1150. The double-path optical path difference may be a function of the ratio of the refractive index of the LCOS SLM 1140 to the thickness of the LCOS SLM 1140. For a given refractive index of the LCOS SLM 1140 and a given thickness of the LCOS SLM 1140, the round trip in and out of the LCOS SLM 1140 at a large angle creates a longer optical path length than the round trip in and out of the LCOS SLM 1140 at a small angle. The path length is proportional to the thickness of the LCOS SLM 1140. In one embodiment, the LCOS SLM may have a first refractive index and a first thickness. For a small angle, the double-path optical path difference of the LCOS SLM having the first refractive index and the first thickness may be half-wave. For a large angle, the double-path optical path difference of the LCOS SLM having the first refractive index and the first thickness may not be half-wave (e.g., may exceed half-wave). The thickness of the LCOS SLM may vary from a first thickness to a second thickness, and the second thickness is less than the first thickness. For a small angle, the double-path optical path difference of the LCOS SLM having the first refractive index and the second thickness may not be half-wave (e.g., may be less than half-wave). For a large angle, the double-path optical path difference of the LCOS SLM having the first refractive index and the second thickness may be half-wave.

[0229] Also, FIGS. 20A and 20B illustrate the use of a polarization-based SLM 1140, although other types of SLMs may also be utilized. FIG. 20C illustrates the use of a deflection-based SLM 1140, such as a movable micromirror-based SLM, for example. As discussed above, such an SLM 1140 may include digital light processing (DLPTM) and digital micromirror device (DMD) technologies. As discussed above, the deflection-based SLM 1140 can couple light from one of the light sources 1110, 1112, 1114 into individual internal coupling optical elements 1360, 1362, 1364 according to the state of the pixels of the SLM 1140. In one state, the light from the light sources 1110, 1112, 1114 will be directed to the individual internal coupling optical elements 1360, 1362, 1364, as illustrated in FIG. 20D. In another state, the light from the light sources 1110, 1112, 1114 will be directed away from the internal coupling optical elements 1360, 1362, 1364, as illustrated in FIG. 20E. In some implementations, on the other hand, in the off state, the black light-absorbing mask between the color filters 2040, 2042, 2044 in the color filter array 2030 can serve as a light dump. As explained above, the color filters 2040, 2042, 2044 may be surrounded and / or separated by a mask, such as a light-absorbing mask (e.g., a black mask). The mask may include a light-absorbing material such that incident light is more absorbed than reflected therefrom. The mask may also be opaque.

[0230] Other variations are also conceivable. The light sources are shown as emitters 1110, 1112, 1114 (e.g., LEDs, laser diodes) coupled to a coupling optical system 1105 such as a non-imaging optical coupling element (e.g., a compound parabolic concentrator (CPC) or a cone), but other configurations are also conceivable. For example, the coupling optical system 1105 (e.g., a CPC) may be tilted with respect to a stack of waveguides. In some cases, the projector (i.e., the optical system 1130 and the SLM 1140) may be tilted with respect to an eyepiece (e.g., a stack of waveguides). In some implementations, the lens optical system 1130 is tilted with respect to the SLM 1140 to reduce distortions such as keystone distortion. A Scheimplug configuration may be employed to reduce such distortions. The components may be tilted as necessary (e.g., the optical system 1130 and / or the spatial light modulator 1140) to more conformally fit around, for example, the head and / or face. As described above, the light emitter and / or the coupling optical system 1105 may be tilted. In some configurations, the assembly, including the waveguides, may be tilted with the side closer to the eye 210 (e.g., the temple side) closer to the eye 210 to increase the perceived field of view of the binocular system as a whole (at the expense of binocular overlap).

[0231] As discussed above, the components and their locations and arrangements can vary. For example, FIG. 20F is a side view of system 2000F that includes cover glass 2050 disposed between stack 2005 and optical system 1130. In some designs, light sources 1110, 1112, 1114 may be disposed on the world side of cover glass 2050 and configured to propagate light through cover glass 2050 to optical system 1130 and SLM 1140. As shown, cover glass 2050 may extend laterally (e.g., parallel to the x-axis) beyond stack 2005 such that light emitted by light sources 1110, 1112, 1114 is incident on optical system 1130 without passing through the waveguides within stack 2005. System 2000F depicts a deflection-based SLM 1140, but a similar configuration of the light sources may also be used in combination with a non-deflection-based SLM or in combination with or within any other configuration or feature disclosed herein.

[0232] FIG. 20G is a side view of system 2000G that includes cover glass 2060 disposed on the world side of stack 2005 (i.e., the side of stack 2005 opposite the proximal side of optical system 1130). In some designs, light sources 1110, 1112, 1114 may be disposed on the world side of cover glass 2050 and configured to propagate light through cover glass 2050 to optical system 1130 and SLM 1140. As shown, cover glass 2060 may extend laterally (e.g., parallel to the x-axis) beyond stack 2005 such that light emitted by light sources 1110, 1112, 1114 is incident on optical system 1130 without passing through the waveguides within stack 2005. System 2000G depicts a deflection-based SLM 1140, but a similar configuration of the light sources may also be used in combination with a non-deflection-based SLM or in combination with or within any other configuration or feature disclosed herein.

[0233] In addition, as discussed above, a configuration that promotes light reuse may be adopted. FIG. 21 is a partial side view of a system 2100 equipped with a configuration that provides light reuse of light from a light source 1110. The light source 1110 may be disposed relative to a polarizer 1115 configured to reuse light having an undesired polarization. The polarizer 1115 may include, for example, a wire grid polarizer that transmits light of a first polarization and retroreflects light of a second opposite polarization. Thus, light 2110 may be emitted from the light source 1110 and impinge on the polarizer 1115. The polarizer 1115 may transmit light of the first polarization so configured for use by a projector (not shown). For example, the SLM may operate properly using the light of the first polarization. The light of the second polarization 2120 is reflected back toward the light source 1110 and may be reused. The polarization of the light 2120 may be modified with respect to the polarization that is rotated after reflection from a portion (e.g., sidewall) of a coupling optical system (not shown) such as a non-imaging optical system like a compound parabolic concentrator (CPC) at various angles. Some light having a suitable polarization (e.g., polarization orientation) that may be passed by the polarizer 1115 may result. Multiple reflections may change the polarization of the light and cause the light to exit with a desired polarization. The reused light 2130 is then emitted back toward the polarizer 1115. Such a configuration may improve efficiency, e.g., energy efficiency, since more of the desired polarization is produced. Also, in addition to or as an alternative, a retarder may be used to change the reflected polarization state and recover the light.

[0234] FIG. 22 shows another configuration including light sources 1110, 1112, 1114 and corresponding light condensing optical systems 2210, 2212, 2214. The light condensing optical systems 2210, 2212, 2214 may include lenses or other optics and may condense the light from the light sources 1110, 1112, 1114. The light sources 1110, 1112, 1114 may be laser diodes or other emitters that emit light over a wide range of angles. The light condensing optical systems 2210, 2212, 2214 may be used to condense much of that light. The light sources 1110, 1112, 1114 may emit light asymmetrically. For example, the light may be emitted in one direction (e.g., the x or z direction) rather than in the orthogonal directions (e.g., the z or x direction) at a wider range of angles. Thus, the light condensing optical systems 2210, 2212, 2214 may be asymmetric. For example, the light condensing optical systems 2210, 2212, 2214 may have different refractive powers in orthogonal directions that may be considered different. The light condensing optical systems 2210, 2212, 2214 may include lenses such as, for example, anamorphic lenses. The light condensing optical systems 2210, 2212, 2214 may also potentially include non-imaging optics. Apertures 2220, 2222, 2224 may be included. A diffuser 2230 may also be included proximal to the apertures 2220, 2222, 2224, for example, when the light sources 1110, 1112, 1114 are lasers such as laser diodes. By using a diffuser proximal to the apertures 2220, 2222, 2224, the apertures may appear to be in the location of the laterally displaced light sources. The apertures 2220, 2222, 2224 may be aligned with internal coupling optical elements on the waveguide or with the waveguide, via the optical system and the SLM, as discussed above. For example, each aperture 2220, 2222, 2224 may be aligned with an individual internal coupling optical element. Similarly, in one implementation as shown in FIG. 16A, each aperture 2220, 2222, 2224 may be aligned with an individual group of (e.g., color selective) internal coupling optical elements.

[0235] A wide range of system variations and configurations are also conceivable as possibilities. For example, linear polarization is described as being propagated through the optical system 1130 to the SLM 1140 and then back through the optical system to the waveguide stack. However, in some designs, circular polarization may be used instead. For example, circular polarization may be directed into the optical system 1130. A retarder, such as a quarter-wave plate, may be arranged so that the incident light passes through the retarder prior to impinging on the SLM. The retarder (e.g., a quarter-wave plate) may be arranged between the optical system 1130 and the SLM 1140. In some cases, as described above, the retarder (e.g., a quarter-wave plate) may be attached to the SLM 1140 using, for example, an adhesive or mechanical fixture. The retarder (e.g., a quarter-wave plate) may convert linear polarization to circular polarization after reflection from the SLM 1140. Thus, in some implementations, circular polarization may pass back through the optical system 1130 towards the stack. For example, another retarder (e.g., a quarter-wave plate) proximal to the analyzer 1150 may convert the circular polarization to linear polarization depending on whether the linear polarization (e.g., orientation) passes through the analyzer or not. The pixels of the SLM 1140 may have states that can be varied to rotate or not rotate the polarization. Further other configurations are also conceivable as possibilities.

[0236] FIG. 23A is a side view of an augmented reality display system 2300 including a light source 2305, a polarization rotator 2307, an optical element (e.g., a lens) 2320 having refractive power, polarizers 2312, 2335 such as a linear polarizer (e.g., a horizontal or vertical polarizer), retarders 2315, 2330, 2340 such as a quarter-wave retarder (e.g., a quarter-wave plate), and at least one waveguide 2348 for outputting image information to a user. Such a configuration can be used to illuminate a reflective spatial light modulator (not shown) such that light emitted from the light source 2305 is coupled into at least one waveguide 2348 so as to be reflected from the spatial light modulator and directed towards the user's eye. The configuration and placement of these elements, particularly the polarizers and retarders, can reduce or eliminate reflections from optical surfaces within the system such as the surface from the optical system 2320, which otherwise could result in afterimage images being visible to the user. For example, optical elements (e.g., polarizers 2312, 2335 and retarders 2315, 2330, 2340) that are polarization selective and / or have a phase difference can be arranged and configured to convert linear polarization to circular polarization that changes from left-handed to right-handed or from right-handed to left-handed in response to reflection from the optical surface. Similarly, such optical elements (e.g., polarizers 2312, 2335 and retarders 2315, 2330, 2340) that are polarization selective and / or have a phase difference can be arranged and configured to convert circular polarization to linear polarization that can be attenuated or filtered out by a polarizer (e.g., a linear polarizer). The reverse, converting linear polarization to circular polarization, is also true, and a circular polarizer may be fabricated with such optical elements (e.g., polarizers 2312, 2335 and retarders 2315, 2330, 2340) that are polarization selective and have a phase difference. For example, a circular polarizer may comprise a linear polarizer and a quarter-wave retarder. The circular polarizer can be used to convert linear polarization to circular polarization having a first state (e.g., chirality) and to filter out circular polarization having a second state (e.g., chirality) of a different first state.For example, a circular polarizer can be used to convert linearly polarized light having a certain orientation into left-handed circularly polarized light and filter out right-handed circularly polarized light, which is circularly polarized light. The circular polarizer can also be used to convert linearly polarized light having a certain orientation into right-handed circularly polarized light and filter out left-handed circularly polarized light, which is circularly polarized light. Other configurations of circular polarizers or optical elements that can be used to convert and reverse convert linearly polarized light into circular polarizer light and can selectively filter linearly polarized light, including a phase difference, can be used to reduce retroreflection from the optical surface, as discussed below in connection with FIGS. 23A and 23B.

[0237] Note that left-handed and right-handed circularly polarized light are illustrated using clockwise and counterclockwise arrows in FIGS. 23A and 23B, respectively. Further, horizontal and vertical linearly polarized light are depicted using horizontal arrows and circular dots, respectively.

[0238] As discussed above, FIG. 23A illustrates the configuration of an extended reality display system 2300, and polarizers 2312, 2335 such as linear polarizers (e.g., horizontal polarizers) and retarders 2315, 2330, 2340 such as quarter-wave retarders (e.g., quarter-wave plates) are arranged to reduce retroreflection from optical surfaces such as the surface of the optical system 2320 in the optical path that illuminates and reflects from a spatial light modulator (not shown). The first polarizer 2312 and the first retarder 2315 are disposed between the light source 2305 and the optical system 2320. The first polarizer 2312 is disposed between the light source 2305 and the first retarder 2315. Similarly, the first retarder 2315 is disposed between the first polarizer 2312 and the optical system 2320.

[0239] As shown, light source 2305 emits light as represented by light ray 2310. In some implementations, light ray 2310 may pass through polarization rotator 2307. The rotator 2307 is optional and can be used to rotate the polarization of the light from light source 2305, e.g., light ray 2310. In various implementations, the rotator 2307 can rotate the angle of polarization (e.g., of linear polarization). For example, the rotator 2307 can rotate the linear polarization of light ray 2310 to an orientation that is aligned with a first polarizer 2312 so that it passes through. In some implementations, the polarization rotator 2307 may, in some cases, comprise a retarder, e.g., a half-wave retarder. The optical axis of the half-wave retarder may be oriented to rotate the polarization of the light from light source 2305 from vertical to horizontal or vice versa. Alternatively, the polarization rotator 2307 may be configured to rotate the angle of polarization of the linear polarization emitted from light source 2305 by different amounts. The polarization rotator 2307 need not be included within the system. For example, in an implementation where light source 2305 emits light having the same polarization as the first polarizer 2312, the polarization rotator 2307 may be excluded. As shown, the light, e.g., light ray 2310, passes through polarizer 2312, shown here as a horizontal polarizer. In instances where the light from light source 2305 is not polarized, it passes through the horizontal polarizer 2312 and the light represented as light ray 2310 is linearly polarized (e.g., horizontally polarized) after passing through the polarizer 2312. It should be understood that although a horizontal linear polarizer is used in this example, the principles taught can also be applied to the use of a vertical linear polarizer. Alternatively, linear polarizers having different orientations other than vertical or linear may also be used.

[0240] The horizontal polarized light 2310 travels here through a retarder 2315, shown here as a quarter-wave retarder. This retarder 2315 includes a sufficient phase difference and can convert linearly polarized light into circularly polarized light. For example, the horizontal polarization may be converted into left-handed circularly polarized light as illustrated by a curved (e.g., clockwise-directed) arrow. In this embodiment, the combination of the polarizer 2312 and the retarder 2315 (e.g., a quarter-wave) forms a circular polarizer, which can be referred to herein as a first circular polarizer, that can convert light of a specific linear polarization (e.g., horizontally or vertically polarized) into a specific circular polarization (e.g., left- or right-handed circular polarization or vice versa). The circular polarizer can also block light of a specific circular polarization (e.g., right- or left-handed circular polarization) depending on its configuration.

[0241] In some implementations, various optical elements have birefringence. In some such cases, the retarder 2315 may include an amount of phase difference sufficient to convert linearly polarized light into circularly polarized light and need not be a quarter-wave plate. A phase difference more or less than a quarter-wave may be included within the retarder 2315 because the phase difference can be contributed by other optical elements. Similarly, the phase difference can be distributed within several optical elements. As another example, multiple retarders may be employed to provide an appropriate amount of phase difference.

[0242] The circularly polarized light 2310 (here, left-handed circular polarization) then passes through the optical system 2320. Unwanted reflections can occur at any interface within the system with media having different refractive indices, such as an air / material interface. These reflections can be a problem if the reflected light is allowed to enter at least one waveguide 2348, as the reflected light can be directed into the user's eye and form a visible "ghost" image within the user's eye. For example, in an instance where a display projects a first image into the user's eye using at least one waveguide 2348, a second faint replica image displaced (e.g., laterally displaced) with respect to the first image can also be seen by the user. Such "ghost" images formed by reflections from optical surfaces directed into the user's eye can be distracting or otherwise degrade the viewing experience. For example, as illustrated in FIG. 23A, light such as the reflected ray 2325 can be reflected from a lens within the optical system 2320. This light can be directed towards at least one waveguide 2348 configured to direct light into the user's eye to present an image there. However, in this case, the circular polarization reverses its chirality. For example, in response to reflection from the lens, the direction of the circular polarization is changed (e.g., from left-handed to right-handed). The right-handed reflected ray 2325 then travels through the retarder 2315 and is converted to linearly polarized light having a different (e.g., orthogonal) linear polarization than that transmitted by the polarizer 2312. In this case, for example, light reflected from the optical surface of the lens is converted by the retarder 2315 to vertically linearly polarized light, which is orthogonal to the polarization transmitted by the horizontal linear polarizer 2312. The horizontal linear polarizer 2312 selectively passes horizontal polarization and filters out vertical polarization. Thus, the reflected ray 2325 is attenuated by the horizontal linear polarizer 2312 and / or not transmitted, preventing or at least reducing the amount of such reflected light from reaching at least one waveguide 2348, or the amount of such reflected light that reaches or is coupled within at least one waveguide 2348 through, for example, internal coupling optical elements (e.g., one or more internal coupling gratings).The result would be similar to a left - hand circularly polarized light ray reflected from a different optical surface of the optical system 2320 or another optical surface on a different optical element.

[0243] As shown, the display system 2300 further includes a second retarder 2330 (e.g., a quarter - wave retarder or a quarter - wave plate) and a second polarizer 2335 (e.g., a linear polarizer) disposed between the optical system 2320 and a spatial light modulator (not shown). In one implementation, the second retarder 2330 and the second linear polarizer 2335 may form a second circular polarizer. The second retarder 2330 is disposed between the optical system 2320 and the second polarizer 2335. Similarly, the second polarizer 2335 is disposed between the second retarder 2330 and the spatial light modulator. Thus, after passing through the optical system 2320, the light ray 2310 may pass through the second retarder 2330 (e.g., a quarter - wave retarder). The second retarder 2330 is configured such that the light ray 2310 is converted from left - hand circular polarization to horizontal linear polarization (e.g., the optical axis is appropriately oriented). Similarly, the second retarder 2330 converts the circular polarization back to the original linear polarization state output by the first polarizer 2312. As discussed below, the second retarder 2330 and the second polarizer 2312 can be useful in reducing the "ghost" image caused by light reflected from the spatial light modulator that passes through an optical surface (e.g., on a refractive - power optical system or lens 2320) as the light travels to at least one optical waveguide 2348.

[0244] The third retarder 2340 (e.g., a quarter-wave retarder or a quarter-wave plate) is disposed between the second polarizer 2335 and the spatial light modulator. Thus, the third retarder 2340 is disposed between the second retarder 2330 and the spatial light modulator. Also, in various implementations, as shown, the second polarizer 2335 is between the second and third retarders 2330, 2340. As shown, the light ray 2310 is linearly polarized upon passing through the second polarizer 2335, and in some implementations, the second retarder 2330 / second polarizer 2335 may convert the light to the original linear polarization of the first polarizer 2312 (e.g., horizontally polarized). This linear polarization is incident on the third retarder 2340. The third retarder 2340 is configured in some implementations to convert the light ray to the same polarization (e.g., left-handed circular polarization in this embodiment) as that output by the first retarder 2315 so that the light ray returns to circular polarization. In one implementation, the spatial light modulator is configured to act on circular polarization. In some implementations, the spatial light modulator is a reflective spatial light modulator that reflects the incident circular polarization back as circular polarization. In some embodiments, the circular polarization reflected from the spatial light modulator may possibly have the same chirality (e.g., left-handed circular polarization) as that incident thereon depending on whether the spatial light modulator pixel is in an "on" or "off" state. In some embodiments, the spatial light modulator may possibly reflect circular polarization of a different chirality (e.g., right-handed circular polarization) from that incident thereon depending on whether the spatial light modulator pixel is in an "on" or "off" state. However, other types of spatial light modulators may also be used.

[0245] FIG. 23A shows light, illustrated as light ray 2342, reflected from a spatial light modulator and traveling towards waveguide 2385. The reflected light ray 2342 is depicted as left-handed circularly polarized light. The light ray 2342 passes through a third retarder 2340. The third retarder 2340 converts circularly polarized light to linearly polarized light. In this embodiment, the left-handed circularly polarized light is converted to horizontally polarized light. The linearly polarized light is transmitted through a second polarizer 2335. In this embodiment, the horizontally polarized light passes through the second polarizer 2335. The linearly polarized light is incident on a second retarder 2330 and is converted to circularly polarized light. In this embodiment, the horizontally polarized light is converted to left-handed circularly polarized light and is transmitted through the optical system 2320. Here again, reflection from an optical surface such as the surface of the optical system 2320 having refractive power can create a ghost image by reflecting it from the spatial light modulator, into at least one of the waveguides 2348, and back to the user's eye. As described above, unwanted reflections can occur at any interface involving media with different refractive indices, such as an air / material interface. As referenced above, the inclusion of the second retarder and polarizers 2330, 2335 can attenuate these reflections and reduce the likelihood of ghost reflections. FIG. 23A depicts, for example, light, illustrated as light ray 2346, reflected from an optical surface of the optical system 2320. The action of reflection from the surface gives rise to the reflected light ray 2346, which is circularly polarized such that it switches chirality, in this embodiment, from left-handed circularly polarized light to right-handed circularly polarized light. The switched circularly polarized light is attenuated by a second circular polarizer formed by the second retarder and polarizers 2330, 2335. As illustrated in FIG. 23A, for example, the reflected circularly polarized light 2346 is incident on the second retarder 2330 and is converted by the second retarder to linearly polarized light having, for example, orthogonal linear polarization different from that selectively transmitted by the second linear polarizer 2335. In this case, for example, the right-handed circularly polarized light reflected from the optical surface of the optical system 2320 is converted by the retarder 2330 to vertically linearly polarized light, which is orthogonal to the polarization selectively transmitted by the polarizer 2335. The second polarizer 2335 attenuates or prevents the transmission of this linearly polarized light.In this embodiment, the light 2346 is vertically polarized, while the second polarizer 2335 is a horizontal polarizer that selectively passes horizontal polarization and filters out vertical polarization.

[0246] In contrast, the light 2342 that passes through the optical system 2320 and is incident on the first retarder 2315 is circularly polarized and has a chirality different from that of the light reflected from the optical surface of the optical system 2320. This light 2342, which is directed towards at least one waveguide 2348, is polarized (e.g., left-handed circularly polarized) and is converted by the first retarder 2315 into linearly polarized light (e.g., horizontally linearly polarized) that is selectively transmitted by the first polarizer 2312. Thus, the light 2342 can reach at least one waveguide 2348, be coupled therein, and be directed towards the user's eye.

[0247] In the embodiment shown in FIG. 23A, the first circular polarizer formed by the first polarizer 2312 and the first retarder 2315 and the second circular polarizer formed by the second retarder 2330 and the second polarizer 2335 are on opposite sides of the optical system 2320, one being closer to the light source 2305 and the other being closer to the spatial light modulator, and are used to reduce reflections that can result in a "ghost image". An additional retarder 2340 is included between the second circular polarizer (e.g., the second polarizer 2335) and the spatial light modulator to convert the light to circular polarization. However, a wide range of variations are possible. For example, only one circular polarizer may be included. Alternatively, additional circular polarizers or other types of polarization optics may be included.

[0248] FIG. 23B illustrates a third circular polarizer that may be added to the augmented reality system 2300 as shown in FIG. 23A. In particular, FIG. 23B depicts a second circular polarizer that includes a second polarizer 2335, a second retarder 2330, and a third retarder 2340, as introduced above, and further depicts a spatial light modulator 2375. This spatial light modulator (SLM) 2375 may include a liquid crystal spatial light modulator (e.g., liquid crystal on silicon or LCOS). In some implementations, the SLM 2375 may be coated with a cover glass 2370.

[0249] FIG. 23B also shows a third circular polarizer that includes a fourth retarder 2345, such as a quarter-wave retarder (e.g., a quarter-wave plate), and a third polarizer 2355, such as a linear polarizer, disposed between the second circular polarizer, which includes the second polarizer 2335 and the second retarder 2330, and the spatial light modulator 2375. The third polarizer 2355 is between the fourth retarder 2345 and the spatial light modulator 2375. An additional fifth retarder 2360, such as a quarter-wave retarder (e.g., a quarter-wave plate), and a compensator 2365 are disposed between the third circular polarizer, which includes the fourth retarder 2345 and the third polarizer 2355, and the spatial light modulator 2375, more specifically, the cover glass 2370 shown in FIG. 23B. The fifth retarder 2360 is between the third polarizer 2355 and the compensator 2365. The compensator 2365 is between the fifth retarder 2360 and the spatial light modulator 2375, more specifically, the cover glass 2370.

[0250] FIG. 23B shows a method in which light from a light source 2305 (shown in FIG. 23A), e.g., a light ray 2310, propagates to a third circular polarizer including a fourth retarder 2345 and a third polarizer 2355 through a second circular polarizer including a retarder 2330 and a second polarizer 2335 and a third retarder 2340. After passing through the second circular polarizer including the retarder 2330 and the second polarizer 2335, the light ray 2310 from the light source 2305 is incident on the third circular polarizer, particularly on the fourth retarder 2345. The fourth retarder 2345 can convert the circular polarization of the light ray 2310 into linear polarization. In the embodiment shown in FIG. 23B, the light ray 2310 is circularly polarized (e.g., left-handed circular polarization) and is converted by the fourth retarder 2345 into linear polarization (e.g., horizontally polarized). This linear polarization proceeds through the third polarizer 2355, which, in FIG. 23B, includes a horizontal polarizer that selectively transmits horizontal polarization. This linear polarization propagates through a fifth retarder 2360 that can include a quarter-wave retarder that converts the linear polarization into circular polarization. In the embodiment shown in FIG. 23B, the horizontal linear polarization 2310 incident on the fifth retarder 2360 is converted into left-handed circular polarization. This circular polarization is incident on and passes through a compensator 2365. The compensator 2365 may include a polarization element that adjusts the polarization to a desired polarization. The compensator 2365 may be used to cancel out the birefringence of various optical elements within the system. For example, the light may be slightly elliptically polarized due to the phase difference contribution of one or more optical elements. In various implementations, the light output from the compensator 2365 is circularly polarized. In the embodiment shown in FIG. 23B, the light output from the compensator 2365 is left-handed circular polarization. In various implementations, the compensator 2365 may be used, for example, to cancel out the residual phase difference within an SLM that may include a liquid crystal (e.g., LCOS) SLM cell. The compensator may introduce an in-plane phase difference and / or an out-of-plane phase difference. In some implementations, the compensator 2365 may include a combination of optical retarders that produce a phase difference that, when combined, can potentially cancel out the residual phase difference from an SLM (e.g., an LCOS panel).

[0251] In FIG. 23B, after passing through the compensator 2365, light is incident on the cover glass 2370 and the SLM 2375. The light incident on the cover glass 2370 and the SLM 2375 is depicted as left-handed circularly polarized light. Depending on the type and state of the spatial light modulator, the SLM 2375 may reflect circularly polarized light of the same chirality. For example, when the pixels of the SLM 2375 are in the "on" state (however, in some implementations, this state may also be the non-driven state), the SLM 2375 may introduce a quarter-wave phase difference for each pass through the SLM 2375. Thus, depending on the reflection, the incident circularly polarized light may remain circularly polarized. In various configurations, the chirality may also remain the same. For example, as shown in FIG. 23B, the incident left-handed circularly polarized light may remain left-handed circularly polarized depending on the reflection. The circularly polarized light reflected from the SLM 2375 is represented by the light beam 2342, passes through the cover glass 2370 and the compensator 2365, and may be incident on the fifth retarder 2360, which converts the circularly polarized light into linearly polarized light. In the embodiment shown in FIG. 23B, the circularly polarized light incident on the fifth retarder 2360 is left-handed, and the fifth retarder 2360 converts the circularly polarized light into horizontally polarized light. The third polarizer 2355 may be configured to selectively transmit the polarization of the light output by the fifth retarder 2360. Thus, in the embodiment shown in FIG. 23B where the light output from the fifth retarder 2360 is horizontally polarized, the third polarizer 2355 selectively transmits the horizontally polarized light. The linearly polarized light transmitted by the polarizer 2355 is incident on the fourth retarder 2345 and is converted into circularly polarized light. In the embodiment shown in FIG. 23B, the circularly polarized light is left-handed circularly polarized light. The light can proceed into the user's eye onto at least one waveguide 2348 through a second circular polarizer including the second retarder 2330 and the second polarizer 2335, an optical system 2320, and a first circular polarizer including the first polarizer 2312 and the first retarder 2315, as discussed above in relation to FIG. 23A.

[0252] However, the light reflected from the optical surface is attenuated by the third circular polarizer, thereby reducing the likelihood that such reflections will reach at least one waveguide 2348, be directed to the user's eye, and produce a ghost image. To illustrate, FIG. 23B shows exemplary ray 2343 reflected from the optical surface of the third retarder 2340, e.g., from the interface between air and the third retarder 2340. As discussed above, reflection can occur at any interface between media having different refractive indices, such as an air / material interface, or at the interface between different dielectric layers. However, circular polarization reverses its chirality in response to reflection. For example, in response to reflection from the surface of the third retarder 2340, the direction of circular polarization is changed (e.g., from left-handed to right-handed). The right-handed reflected ray 2343 then passes through the fourth retarder 2345 and is converted to linearly polarized light having, for example, linearly polarized light that is different from that selectively transmitted by the third polarizer 2355, e.g., orthogonal linearly polarized light. In this case, for example, the light reflected from the optical surface of the third retarder 2340 is converted by the fourth retarder 2345 to vertically linearly polarized light, which is orthogonal to the polarization selectively transmitted by the third polarizer 2355. The third polarizer 2355 selectively passes horizontally polarized light and filters out vertically polarized light. Thus, the reflected ray 2343 is attenuated by the third polarizer 2355 and / or not transmitted, preventing it from reaching at least one waveguide 2348 (e.g., by reflecting from another surface), or at least reducing the amount of such reflected light that reaches or is coupled within at least one waveguide 2348.

[0253] The results can be similar to circularly polarized light reflected from different optical surfaces. FIG. 23B shows, for example, the reflection of an incident light ray 2310 from the optical surface of a fourth retarder 2345. The reflection 2350 from the fourth retarder 2345 switches the chirality of the polarization. For example, an incident light ray 2310 depicted as left-handed circularly polarized light is converted into a light ray 2350, shown as having right-handed circular polarization, in response to the reflection. The reflected light ray 2350 passes through the third retarder 2340 and is converted into vertically polarized light. This vertically polarized light is selectively attenuated or filtered out by the second polarizer 2335.

[0254] As described above, the pixels of the SLM2375 can be in, for example, an "on" state (although in some implementations, a non-driven state), and the light incident on the pixel of the SLM2375 is reflected therefrom and coupled into at least one waveguide 2348 and directed to the user's eye. However, the pixels of the SLM2375 can be in an "off" state (which can be a driven state in some implementations), in which case the light incident on the pixels of the SLM2375 is not coupled into at least one waveguide 2348 and not coupled into the user's eye. In this "off" state, for example, various implementations of the SLM2375 may not be able to introduce a phase difference in response to reflection therefrom. Thus, in the embodiment shown in FIG. 23B, the circularly polarized light incident on the SLM2375 can remain circularly polarized in response to reflection from the SLM2375. However, the handedness of the circularly polarized light may change in response to reflection from the SLM2375. For example, the light ray 2310 shown in FIG. 23B, which is left-handed circularly polarized light incident on the SLM2375, can be converted to right-handed circularly polarized light in response to reflection from the SLM2375. However, the reflected light can be selectively attenuated by a third polarizer 2355. For example, the right circularly polarized light reflected from the SLM2375 can pass through the cover glass 2370, the compensator 2365, and the fifth retarder 2360. The fifth retarder 2360 can convert the right-handed circularly polarized light to vertically polarized light, which is selectively attenuated by a third polarizer 2355 that may include a horizontal polarizer. Thus, in various implementations, the fifth retarder 2360 may convert the light reflected from the pixels of the SLM2375 to linearly polarized light that is orthogonal to the linearly polarized light selectively transmitted by the third polarizer 2355 when the pixels of the SLM are in the "off" state. This third polarizer 2355 can thus selectively attenuate this linearly polarized light, thereby reducing or blocking the light from that pixel of the SLM2375 from reaching at least one waveguide 2348 and not being directed into the eye.

[0255] Modifications and the like in the polarization optical element, and modifications in the configuration are also conceivable as possibilities. For example, more or fewer circular polarizers may be included. In various implementations, for example, the third circular polarizer, which includes the fourth retarder 2345 and the third polarizer 2355, is excluded as shown in FIG. 23C. In this particular implementation, the fourth retarder 2345, the third polarizer 2355, and the fifth retarder 2360 are not included in the system. FIG. 23C illustrates the design of the augmented reality system 2300, including the components illustrated in FIGS. 23A and 23B, excluding the fourth retarder 2345, the third polarizer 2355, and the fifth retarder 2360. Note that even if the third circular polarizer is excluded, the augmented reality display system is still configured to reduce afterimage images. The second circular polarizer reduces reflections that would otherwise contribute to afterimage images, for example. For illustration purposes, FIG. 23C depicts the light reflected from the third retarder 2340, illustrated as light ray 2380. The action of reflection from the surface of the third retarder 2340 produces the reflected light ray 2380, which is circularly polarized to switch chirality. In this embodiment, the polarization is switched from left-handed circular polarization to right-handed circular polarization. The switched circular polarization 2380 then passes through the compensator 2365 and is incident on the cover glass 2370 and the SLM 2375. As discussed above, the SLM 2375 can reflect circular polarization of the same chirality. Therefore, the incident right-handed circular polarization can remain right-handed circular polarization in response to reflection. The circular polarization reflected from the SLM 2375 is represented by the light ray 2382 and can then pass through the cover glass 2370 and the compensator 2365 and be incident on the third retarder 2340. The switched circular polarization 2382 is attenuated by the second circular polarizer, particularly by the third retarder 2340 and the polarizer 2335. As shown in FIG. 23C, for example, the circular polarization 2382 reflected from the SLM 2375 is incident on the third retarder 2340 and is converted by the third retarder 2340 into linearly polarized light having, for example, orthogonal linear polarization, different from that selectively transmitted by the second linear polarizer 2335.In this case, for example, the right-handed circular polarization 2382 is converted into vertical linear polarization by the third retarder 2340, which is orthogonal to the polarization selectively transmitted by the second polarizer 2335. The second polarizer 2335 attenuates or prevents the transmission of this linearly polarized light.

[0256] Reflections that can contribute to ghosting can also potentially be reduced by tilting optical surfaces within the system. FIG. 24 illustrates an exemplary configuration having a tilted optical surface for reducing reflections that can produce ghosting. FIG. 24 shows an augmented reality display system 2400 that emits light represented by a light ray 2310 that passes through any number of polarizers, retarders, lenses, and / or other optical components as the light travels towards a spatial light modulator (SLM) 2375. Optionally, a first polarizer 2312, a first retarder 2315, and a lens 2320 that form a first circular polarizer are shown in FIG. 24 for illustrative purposes. However, additional components may be included, or components may be excluded, or arranged or configured differently. In the illustrated embodiment, the SLM 2375 includes a cover glass 2370 therewith. The cover glass 2370 can be a contributing factor to reflections that produce ghost images. Thus, in some implementations, the cover glass 2370 can be shaped so as to direct reflections that can result in ghost images away so as not to be directed into the user's eye. As shown, the cover glass 2370 has a surface that can be tilted such that the surface is not parallel to other components or optical surfaces of the system (e.g., the SLM 2375, the first retarder 2315, the first polarizer 2312, at least one waveguide 2348, etc., or their optical surfaces). The major surface of the cover glass 2370 can have a normal that is tilted such that it is not aligned with or parallel to the optical axis of the optical components therein, such as the augmented reality display system 2400 or the optical system 2320. By being tilted, the reflection from the optical surface of the cover glass 2370 can be directed away from at least one waveguide 2348 so as to internally couple the light into at least one waveguide 2348 and reduce the likelihood that the reflection from the cover glass 2370 will be incident on at least one waveguide 2348 or an internal coupling optical element (e.g., an internal coupling grating or a diffractive optical element).As depicted, the reflected light 2405 is directed away from at least one waveguide 2348 such that it returns towards the light source 2305 and such that such light can ultimately reach the user's eye. In some implementations, the reflected light 2405 is directed back towards the light source and at least a portion thereof can be reused at the light source 2305.

[0257] FIG. 24 depicts a cover glass 2370 having an angled surface, and the angled optical surface that deflects reflections away so that they are not coupled into at least one waveguide 2348 can be included on any component within the system where unwanted reflections are a concern. Thus, the optical surfaces on other components such as polarizers, retarders, etc. may be angled to reduce reflections that are coupled into at least one waveguide 2348 and into the user's eye. Variations in the shape and size of the cover glass 2370 or other optical components are also conceivable. The cover glass 2370 or other optical components may be, for example, thinner. Similarly, the cover glass 2370 or other optical components may have an aspect ratio (length to thickness) different from that shown in FIG. 24. In some implementations, the cover glass 2370 or other optical components are wedge-shaped. However, other shapes are also conceivable.

[0258] Still other arrangements are also conceivable. FIG. 25 illustrates an implementation of an extended reality display system 2500 that is similar to, but further includes a light dump 2505 for absorbing light directed thereto, to the system 2400 shown in FIG. 24. The system 2500 includes a cover glass 2370 that is tilted to direct reflection 2510 from the cover glass 2370 to the light dump 2505 instead of being directed back to the light source 2305. The light dump 2505 may include a light absorbing material or structure configured to absorb light. The location of the light dump 2505 can vary depending on the implementation, for example, depending on the angle of the tilted cover glass 2370. As discussed above, this approach can also be applied to other optical surfaces within the system. Additionally, the shape and size of the optical elements may vary.

[0259] A wide range of variations in extended reality displays are also conceivable. Variations in polarization optical elements are also conceivable. For example, a horizontal polarizer is used, but in some implementations, a vertical polarizer or a combination of horizontal and vertical polarizers is employed. Additionally, a polarizer characterized by polarization other than vertical or horizontal may be used. Similarly, the light shown in the figures need not be horizontally polarized and may be vertically polarized. Similarly, light shown to be vertically polarized may be horizontally polarized or vice versa in different implementations. Linear polarization with polarization other than vertical or horizontal may also be used.

[0260] In addition, the retarder may be configured differently. For example, the polarization in the figure need not be left-handed circular polarization and may be right-handed circular polarization, and / or the right-handed polarization may be left-handed circular polarization. Further other variations are also conceivable. Different retarder configurations can be employed to produce combinations of left-handed and / or right-handed polarizations different from those shown. Also, in some implementations, elliptical polarization may potentially be used instead of circular polarization. The retarder may be employed, for example, to convert elliptical polarization to linear polarization and vice versa. The linear polarizer can be used to filter light and may be used to reduce ghost reflections as described herein.

[0261] In some implementations, other types of polarization elements and their configurations are employed. For example, the retarder is not limited to a quarter-wave retarder or a quarter-wave plate. For example, in some implementations, various optical elements have birefringence. In some such cases, any one or more of the retarders 2315, 2330, 2340 may include an amount of phase difference sufficient to convert linear polarization to circular polarization and need not be a quarter-wave retarder. More or less than a quarter-wave of phase difference may be included within any one or more of the retarders 2315, 2330, 2340 since the phase difference may be contributed by other optical elements. Similarly, the phase difference can be distributed among several optical elements. As another example, multiple retarders may be employed to provide an appropriate amount of phase difference. Also, as described above, in some implementations, elliptical polarization may potentially be used instead of circular polarization. The retarder may be employed, for example, to convert elliptical polarization to linear polarization and vice versa. The linear polarizer can be used to filter light and may be used to reduce ghost reflections as described herein.

[0262] In addition, the optical component may be in the form of an optical layer, sheet, and / or film and stack or one or more layers, sheets, and / or films. Thus, different polarization elements, different amounts, locations, and arrangements may be used. For example, one or more of the retarder and / or polarizer may comprise a film.

[0263] In some implementations, the spatial light modulator may operate differently. For example, the spatial light modulator may act on light other than circularly polarized light and / or output light other than circularly polarized light.

[0264] In the foregoing specification, the present disclosure has been described with reference to its specific embodiments. However, it will be apparent that various modifications and changes can be made therein without departing from the broader spirit and scope of the present disclosure. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a limiting sense.

[0265] In fact, the systems and methods of the present disclosure each have several innovative aspects, any of which do not alone participate in or are required for the desirable attributes disclosed herein. The various features and processes described above may be used independently of one another or combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of the present disclosure.

[0266] Certain features described herein in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. Further, features may be described above as acting in a certain combination and may further be claimed as such, first, but one or more features from the claimed combination may in some cases be deleted from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination. No single feature or group of features is necessary or essential to all embodiments.

[0267] Tilting the spatial light modulator As discussed above, the various eyepieces used within a head-mounted display may be configured to direct light with different amounts of divergence into the eye, as if originating from objects located at different distances away from the user. For example, a first group of waveguides may externally couple light having a first divergence amount, and a second group of waveguides may externally couple light having a second divergence amount, where the second divergence amount is different from (e.g., less than) the first divergence amount. Similarly, a first group of waveguides may externally couple light having a first divergence amount, and a second group of waveguides may externally couple collimated light. As a result, an image formed by light from the first group of waveguides may provide visual cues associated with a closer object, while an image formed by light from the second group of waveguides may provide visual cues associated with a more distant object. As discussed above, the waveguides may thus have a refractive power associated therewith to provide divergence or collimation. Each group of waveguides may also include a plurality of waveguides, for example, to present different color components (e.g., red, green, and blue). As discussed herein, a head-mounted display may thus enjoy advantages by being configured to switch between directing light to a first group of waveguides (e.g., having a first refractive power associated therewith to produce an image that appears to originate from a first distance or a set of first distances) when in a first state, and directing light to a second group of waveguides (e.g., having a second different refractive power associated therewith to produce an image that appears to originate from a second distance or a set of second distances) when in a second state. For example, the head-mounted display may switch between a first state configured to provide an image that appears relatively close, and a second state configured to provide an image that appears relatively far.In various configurations disclosed herein, to provide such switching, an extended reality display system may include a spatial light modulator (SLM) that tilts from a first orientation to a second orientation and directs light to either a first group of internal coupling optical elements for a first group of waveguides or a second group of internal coupling optical elements for a second group of waveguides and may provide an image thereto.

[0268] One such extended reality display device, in which a spatial light modulator (SLM) is configured to tilt between two or more orientations (e.g., a first and a second orientation) and direct light to different internal coupling optical elements in different directions so as to couple the light into different groups of waveguides, is shown in FIGS. 26A-26D.

[0269] FIG. 26A shows an extended reality display system 2600 including a light source 1110, a spatial light modulator array (SLM) 2610, and an optical system 1130 disposed in the optical path therebetween. The light source 1116 emits light that passes through the optical system 1130 and is incident on the SLM 2610. The SLM 2610 is reflective and reflects the light back into the optical system 1130. The extended reality display system 2600 further includes an eyepiece 2602, a waveguide stack 2605 including one or more waveguides 2603. The optical system 1130 is also disposed in the optical path between the SLM 2610 and the waveguide stack 2605. As shown in FIGS. 26A and 26B, the light 1116 from the light source reflected from the SLM 2610 is incident on the waveguide stack 2605.

[0270] The waveguide stack 2605 may each include a set of two or more waveguides 2603 and a set of two or more internal coupling optical elements. For example, FIGS. 26A and 26B illustrate a first set of waveguides 2607 having a first set of internal coupling optical elements 2614 and a second set of waveguides 2609 having a second set of internal coupling optical elements 2616. In this design, the first set of internal coupling optical elements 2614 includes three internal coupling optical elements, namely, the first, second, and third internal coupling optical elements 2650, 2652, and 2654, to internally couple three different colors, such as red, green, and blue, into three waveguides 2603 within the first set of waveguides 2607. Similarly, the second set of internal coupling optical elements 2616 also includes three internal coupling optical elements, namely, the first, second, and third internal coupling optical elements 2640, 2642, and 2644, to internally couple three different colors, such as red, green, and blue, into three waveguides 2603 within the second set of waveguides 2609.

[0271] As shown in FIGS. 26A and 26B, the SLM 2610 is configured to direct light either into the first set of internal coupling elements 2614 and the first set of waveguides 2607 when in the first state or into the second set of internal coupling elements 2616 and the second set of waveguides 2609 when in the second state. For example, in FIGS. 26A and 26B, the SLM 2610 is shown to rotate about the axis 2615. In some embodiments, the axis 2615 is parallel to the waveguides within the waveguide stack 2605 (e.g., parallel to the z-axis). In particular, the SLM 2610 is shown to be tilted counterclockwise by an angle θ (+θ) with respect to a plane parallel to the eyepiece 2602 and the waveguide stack 2605 when in the first state and clockwise by an angle, θ (-θ) with respect to a plane parallel to the eyepiece and the waveguide stack when in the second state. In the examples shown in FIGS. 26A and 26B, the tilts are the same angle θ in opposite directions, but the angles need not be the same.

[0272] In various implementations, the augmented reality display system 2600 may include more than one light source. For example, a set of light sources 1116 may include three light sources 1110, 1112, 1114, as shown in FIG. 26C depicting a front view of the eyepiece lens 2602 including the waveguide stack 2605. The light sources 1110, 1112, 1114 may be laterally displaced relative to each other as shown in FIG. 26C. In this embodiment, the set of light sources 1116 includes three light sources 1110, 1112, 1114, although more or fewer numbers are also conceivable as possibilities. The light sources 1110, 1112, 1114 may each be light sources of different colors, for example, red, green, and blue light sources. In this design, the light sources 1110, 1112, 1114 are shown to be displaced relative to each other along a direction parallel to an axis 2615 (e.g., parallel to the z-axis) around which the SLM 2610 rotates.

[0273] In the embodiments shown in FIGS. 26A-26C, the SLM 2610, when in the first or second state respectively, directs light from the light sources 1110, 1112, 1114 within the set of light sources 1116 to the internal coupling optical elements 2650, 2652, 2654, 2640, 2642, 2644 within the set of first or second internal coupling optical elements 2614, 2616, and is configured to be tilted so as to internally couple the light into one of the first or second sets of waveguides 2607, 2609. FIG. 26A illustrates the SLM 2610 tilted at an angle (e.g., +θ) 2612a such that light from the light source 1110 is directed to one of the internal coupling optical elements 2650, 2652, 2654 within the set of first internal coupling optical elements 2614 as opposed to one of the internal coupling optical elements 2640, 2652, 2644 within the set of second internal coupling optical elements 2616. The internal coupling optical elements within the set of first internal coupling optical elements 2614 may then couple the light into one of the waveguides 2603 within the set of first waveguides 2607 as opposed to one of the waveguides 2603 within the set of second waveguides 2609. FIG. 26B illustrates the SLM 2610 tilted at an angle (e.g., -θ) 2612b such that light from the light source 1116 is directed to one of the internal coupling optical elements 2640, 2642, 2644 within the set of second internal coupling optical elements 2616 as opposed to one of the waveguides 2650, 2652, 2654 within the set of first internal coupling optical elements 2614. The internal coupling optical elements within the set of second internal coupling optical elements 2614 may then direct more light into one of the waveguides 2603 within the set of second waveguides 2609 as opposed to one of the waveguides 2603 within the set of first waveguides 2607.

[0274] In this design, the sets 2614, 2616 of the first and second internally coupled optical elements are arranged on the opposite side of the set of light sources 1116, which may include the light sources 1110, 1112, 1114. Therefore, when in the first state, the SLM 2610 may be inclined towards the set 2614 of the first internally coupled optical elements on one side of the light sources 1110, 1112, 1114, and when in the second state, it may be inclined towards the set 2616 of the second internally coupled optical elements on the opposite side of the light sources.

[0275] Figure 26D is a side view of the eyepiece lens 2602 from a side different from those shown in FIGS. 26A and 26B. In FIG. 26D, the internally coupled optical elements 2650, 2652, 2654, 2640, 2642, and 2644 and the light sources 1110, 1112, 1114 are laterally displaced relative to each other in the direction of the axis 2615 (e.g., the Z direction) around which the SLM 2610 is inclined. In particular, the first, second, and third internally coupled optical elements 2650, 2652, 2654, 2640, 2642, and 2644 (both within the sets 2614, 2616 of the first and second internally coupled elements) are laterally displaced relative to each other in the direction of the axis (e.g., the Z direction) around which the SLM 2610 is inclined. Similarly, the three light sources 1110, 1112, 1114 are laterally displaced relative to each other in the direction of the axis 2615 (e.g., the Z direction) around which the SLM 2610 is inclined. However, when the SLM 2610 is properly inclined, the first, second, and third light sources 1110, 1112, 1114 are aligned (along the Z direction) with the respective ones of the first, second, and third internally coupled optical elements 2650, 2652, 2654, 2640, 2642, and 2644 within the sets 2614, 2616 of the first and second internally coupled optical elements such that the first, second, and third light sources 1110, 1112, 1114 will each direct light into the first, second, and third internally coupled optical elements 2650, 2652, 2654, 2640, 2642, and 2644 within the sets 2614, 2616 of the first and second internally coupled optical elements.

[0276] As discussed above, in some implementations, each set of waveguides 2607, 2609 may be configured to output light having different amounts of divergence, convergence, or collimation. FIG. 26D shows, for example, a first set of waveguides 2607 including a first set of external coupling optical elements 2666 configured to output light 2665 and diverge a first amount, and a second set of waveguides 2607 including a second set of external coupling optical elements 2676 configured to output light 2675 and diverge a second amount. In this example, FIG. 26D shows the first divergence amount as being greater than the second divergence amount. As discussed above, in some implementations, one of the sets of waveguides 2607, 2609 may be configured to direct collimated light toward the user's eye, while another set of waveguides is configured to direct diverging light toward the user's eye. Thus, in various implementations, a first set of internal coupling optical elements 2614, including internal coupling optical elements 2650, 2652, and 2654, receives light in accordance with the tilt of the SLM 2610 and couples it into the first set of waveguides 2607, which outputs light 2665 to form an image that appears to originate from a first distance (e.g., a closer distance), and a second set of internal coupling optical elements 2616, including 2640, 2642, and 2644, receives light and couples it into the second set of waveguides 2609, outputting light 2675 to form an image that appears to originate from a second distance (e.g., a farther distance). The external coupling optical elements 2666 and 2676 are referred to above as producing divergence and / or collimation, but in some implementations, one or more lenses or other optical elements having refractive power may be included to provide divergence and / or collimation. The lenses may be included, for example, between the first and second sets of waveguides 2607, 2609 and / or between the second set of waveguides 2609 and the user's eye in some implementations. In any such design, the external coupling optical elements 2666 and 2676 may or may not be configured to include refractive power or otherwise impart divergence to, and / or collimate, the light.

[0277] Other configurations are also conceivable. For example, as illustrated in FIG. 27, in some implementations, different sets of waveguides 2707, 2709 are configured to provide different fields of view for virtual image content. In some cases, these fields of view may both be summed to provide a larger field of view for the user. For example, a first set of waveguides 2707 may provide a field of view of 0° to +45°, while a second set of waveguides may provide a field of view of 0° to -45°. The SLM 2610 may switch between directing light to the first and second sets of waveguides 2707, 2709 by reciprocally tilting the SLM 2610 to provide an aggregated field of view of -45° to +45°. The SLM 2610 may switch between the first and second sets of waveguides 2707, 2709 at a rate that is fast enough such that the user cannot perceive the switch. FIG. 27 shows, for example, a first set of internal coupling optical elements 2614 including internal coupling optical elements 2650, 2652, and 2654 configured to direct light into the first set of waveguides 2707, and a second set of internal coupling optical elements 2616 including internal coupling optical elements 2640, 2642, and 2644 configured to direct light into the second set of waveguides 2709. The first set of waveguides 2707 has a first set of external coupling optical elements 2766 configured to output light corresponding to virtual image content within a first angular field of view 2782, and the second set of waveguides 2709 has a second set of external coupling optical elements 2776 configured to output light corresponding to virtual image content within a second angular field of view 2784. FIG. 27 shows a first angular field of view 2782 directed in a different direction than the second field of view angle 2784. However, in some implementations, portions of each of the first and second field of view angles 2782, 2784 may overlap. However, the overlap may be less than 50%, 25%, 10%, 5%, 1% of the fields of view provided by the sets of waveguides 2707, 2709, or any range between these values in some implementations. The different fields of view may together provide a field of view for virtual image content that is larger than only one of the fields of view.In some implementations, the angular fields of view from each set of waveguides 2707, 2709 need not overlap or may diverge. Still other variations are also conceivable. For example, a set of three waveguides may provide three different fields of view. The SLM 2610 can switch between providing light to these three sets of waveguides as discussed above. In one implementation, the total field of view provided by a set of waveguides is larger than any one of the individual fields of view.

[0278] Other designs are also conceivable. For example, in some implementations, different sets 2807, 2809 of waveguides may provide an increased eye box. As illustrated in FIG. 28, for example, each set 2614, 2616 of internal coupling optical elements may direct light into individual sets 2807, 2809 of waveguides having external coupling optical elements 1180 that laterally shift or offset the light relative to each other and provide an increased range of lateral positions that are conceivable for a user's eye. FIG. 28 particularly includes a first set 2614 of internal coupling optical elements including internal coupling optical elements 2650, 2652, and 2654 that can direct light into a first set 2807 of waveguides having a first set 2866 of external coupling optical elements, and a second set 2614 of internal coupling optical elements including internal coupling optical elements 2640, 2642, and 2644 that can direct light into a second set 2809 of waveguides having a second set 2876 of external coupling optical elements. As discussed above, the SLM 2610 may switch between directing light into the first and second sets 2807, 2809 of waveguides and the first and second sets 2866, 2876 of external coupling optical elements by reciprocally tilting. The first set 2866 of external coupling elements is laterally offset or displaced from the second set 2876 of external coupling elements. Advantageously, the first and second sets 2866, 2876 of external coupling optical elements output light from a larger area than only one of the first and second sets 2866, 2876 of external coupling optical elements. The larger area of the projection can be converted into an increased eye box for a user to view an image within the display. Thus, the larger area can accommodate variations in the lateral position of the user's eye 210. For example, the user's interpupillary distance may be such that the eye 210 is more or less closer to the nose or temple relative to the eyepiece 2602. However, the combination of the external coupling optical elements 1180 increases the location along a lateral direction (e.g., the z direction) where the eye 210 can be positioned and still receive light from the external coupling optical elements 2866, 2876 and view the virtual image content.The SLM2610 is fast enough so that the user cannot perceive the switching, but appears to have a larger inbox, and can switch between a set 2807, 2809 of first and second waveguides, and thus between a set 2614, 2616 of first and second internal coupling optical elements, at a rate.

[0279] The light source and the internal coupling optical elements may be arranged and / or configured differently. In some embodiments as shown in FIGS. 29A and 29B, the light source 2910 may be, for example, a multi - color light source capable of emitting light of different colors at different times. For example, the light source 2910 may emit three colors, emitting a first color and amounts of a second and a third color below a negligible amount in a first time period, a second color and amounts of a first and a third color below a negligible amount in a second time period, and a third color and amounts of a first and a second color below a negligible amount in a third time period. For example, the light source 2910 may emit red, green, and blue (RGB) light, emitting red and amounts of green and blue below a negligible amount in a first time period, green and amounts of red and blue below a negligible amount in a second time period, and blue and amounts of red and green below a negligible amount in a third time period. These cycles can be repeated, and the SLM2610 can be coordinated to produce a suitable pattern of pixel states for a particular color (red, green, or blue) and provide the appropriate image color components for a given image frame.

[0280] Note that the different waveguides 2990, 2992, 2994, 2930, 2932, and 2934 of the waveguide stack 2605 may each be configured to output light with different individual colors. For example, as depicted in FIG. 29A, the first, second, and third waveguides 2930, 2932, 2934 within the first set 2607 of waveguides associated with the individual first, second, and third internal coupling optical elements 2950, 2952, and 2954 may each be configured to output light of the first, second, and third colors (e.g., blue, green, and red), respectively. Similarly, the first, second, and third waveguides 2990, 2992, 2994 within the second set 2609 of waveguides associated with the individual first, second, and third internal coupling optical elements 2940, 2942, and 2944 may also each be configured to output light of the first, second, and third colors (e.g., blue, green, and red), respectively. The different internal coupling optical elements 2950, 2952, 2954 within the first set 2607 of waveguides, including 2930, 2932, and 2934, are laterally aligned (e.g., as shown in FIG. 29B) such that the optical paths extend through each of the internal coupling optical elements within the first set 2614 of internal coupling optical elements, or are arranged on top of and / or below one another and laterally aligned with respect to one another. Thus, light propagates along the path and, in some cases, may be incident on all three internal coupling optical elements 2950, 2952, 2954 within the first set 2614 of internal coupling optical elements. Similarly, the different internal coupling optical elements 2940, 2942, 2944 within the second set 2609 of waveguides, including 2990, 2992, and 2994, may also be laterally aligned (e.g., as shown in FIG. 29B) such that the optical paths extend through each of the internal coupling optical elements within the second set 2616 of internal coupling optical elements, or are arranged on top of and / or below one another and laterally aligned with respect to one another. Thus, light propagates along the path and, in some cases, may be incident on all three internal coupling optical elements 2940, 2942, 2944 within the second set 2616 of internal coupling optical elements.However, the first set of internal coupling optical elements 2614 may be laterally offset from the second set of internal coupling optical elements 2616 such that light can be directed to either the first set or the second set of internal coupling optical elements 2614, 2616 depending on the tilt of the SLM 2610.

[0281] The internal coupling optical elements 2950, 2952, 2954, 2940, 2942, 2944 may be color selective. For example, the first internal coupling optical elements 2950, 2940 within the first and second sets 2614, 2616 of internal coupling optical elements may be configured to internally couple a non - negligible amount of a first color and an amount of a second and third color that is less than negligible. Similarly, the second internal coupling optical elements 2952, 2942 within the first and second sets 2614, 2616 of internal coupling optical elements may be configured to internally couple a non - negligible amount of a second color and an amount of a first and third color that is less than negligible. Additionally, the third internal coupling optical elements 2952, 2942 within the first and second sets 2614, 2616 of internal coupling optical elements may be configured to internally couple a non - negligible amount of a third color and an amount of a first and second color that is less than negligible. Other configurations are also conceivable. For example, different waveguides within the first set 2607 of waveguides can be configured to receive and output different colors from the individual corresponding waveguides within the second set 2609 of waveguides, and vice versa. Of course, other colors are also conceivable, for example, the light source 2910 may emit other colors, and the color - selective internal coupling optical elements 2950, 2952, 2954, 2940, 2942, 2944 can be configured for such other colors. Additionally, individual red, green, and blue emitters may be positioned close enough to function effectively as a single pupil light source. For efficiency, emitters of any color may be combined with beam - conditioning elements such as reflectors, films, and holograms to match the angular output of the light source to the field of view to be displayed. In some implementations, the red, green, and blue emitters may be combined with lenses and dichroic splitters to form a single red, green, and blue pupil source. The multiplexing of a single pupil may be extended, either in addition to or instead of color selectivity, and may include the use of polarization - dependent gratings and polarization switching. These color or polarization gratings may also be used in combination with multiple display pupils and can increase the number of addressable layers.

[0282] A wide range of variations are possible. For example, a set of two waveguides 2607, 2609 is discussed above with reference to FIGS. 26A - 29B, but more sets of waveguides (and thus more corresponding sets of internal coupling optical elements) may be included. For example, the SLM 2610 can be configured to tilt at different angles to switch to different states, for example, to couple light from a light source into one of three, four, or more sets of waveguides. The SLM 2610 may have, for example, three, four, or more states where the SLM is tilted at different angles, such as θ1, θ2, and θ3, and the light is directed into one of the first, second, or third sets of internal coupling optical elements of the first, second, or third set of waveguides. Similarly, a set of waveguides may include more or fewer waveguides 2603. For example, each set of waveguides may include only two waveguides 2603. Similarly, in such an implementation, each set of internal coupling optical elements may include only two internal coupling optical elements. Alternatively, a set of waveguides may include four or more waveguides 2603. In such an implementation, the set of internal coupling optical elements may include four or more internal coupling optical elements.

[0283] FIG. 30A shows a configuration where instead of one or more waveguides being used to provide light adjusted to create an image that appears to originate from a certain depth, a single waveguide is used to provide such light. In FIG. 30A, for example, two such waveguides (referred to as the first and second waveguides 3004, 3006) are used for two separate depths. Each waveguide 3004, 3006 is configured to receive light of multiple colors from a multi - color light source 3010 depending on the tilt state of the tiltable spatial light modulator 2610. Non - color - selective or broadband internal coupling optical elements 3050, 3040 that are laterally displaced may be configured to receive light from the light source 3010 and couple it into the individual first and second waveguides 3004, 3006 in various implementations.

[0284] FIG. 30A is a side view of an augmented reality display system including, for example, a waveguide stack 2605 and an eyepiece lens 2602. The waveguide stack 2605 includes first and second waveguides 3004, 3006, each waveguide including an individual internal coupling optical element 3050, 3040 and an individual external coupling optical element 3060, 3070 therewith. The internal coupling optical elements 3040 and 3050 may be configured to couple light of multiple colors into their respective waveguides. Thus, these internal coupling optical elements 3050, 3040 may be referred to herein as broadband, multi-color, or non-color-selective internal coupling optical elements because these internal coupling optical elements couple light of different colors. For example, in some implementations, each of these internal coupling optical elements 3050, 3040 is configured to internally couple first, second, and third colors (e.g., red, green, and blue light) into associated waveguides 3004, 3006, and the internal coupling optical elements are included therein such that the colored light is guided within the waveguide by TIR. Such broadband internal coupling optical elements 3040 and 3050 may operate, for example, across a wide range of wavelengths within the visible range, or may select wavelength or wavelength region spreading, for example, across the visible range. Thus, such broadband or multi-color or non-color-selective internal coupling optical elements 3040 and 3050 may be configured to redirect light of various different colors (e.g., red, green, and blue) into the waveguide and be guided therein by TIR. Similarly, each of these external coupling optical elements 3060 and 3070 may include a broadband external coupling optical element. Such broadband external coupling optical elements 3060 and 3070 may operate, for example, across a wide range of wavelengths within the visible range, or may select wavelength or wavelength region spreading, for example, across the visible range. Thus, such broadband or multi-color or non-color-selective external coupling optical elements 3060 and 3070 may be configured to redirect light of various different colors (e.g., red, green, and blue) from the waveguide out to the eye.Red, green, and blue (RGB) colors are referred to herein in connection with, for example, but not limited to, light sources, internal coupling optical elements, external coupling optical elements, and / or waveguides, etc. Other colors or color systems, including, for example, but not limited to, cyan, magenta, and yellow (CMY), etc., may also be used in addition to, or as an alternative to, these.

[0285] In some implementations, the augmented reality display system 2600 may include a tilted stage on which the SLM 2610 is disposed. The tilted stage may include at least one actuator capable of tilting the tilted stage. In some implementations, the actuator may be capable of receiving a signal and tilting the tilted stage in response to a tilt signal.

[0286] As discussed above, in some implementations, the SLM 2610 may be configured to switch between two or more states. Each state of the SLM 2610 may correspond to a different angle. For example, the SLM 2610 may tilt to a first state corresponding to a first angle and to a second state corresponding to a second angle. For example, FIGS. 26A and 26B show a first angle 2612a and a second angle 2612b. In some embodiments, the first angle 2612a and the second angle 2612b may include angles including, for example, but not limited to, -45 to +45 degrees, -30 to +30 degrees, -20 to +20 degrees, -10 to +10 degrees, or -5 to +5 degrees, or any range between any of these values. For example, the first and second angles 2612a may be at least ±7 degrees. In another example, the first angle 2612a and the second angle 2612b may include an angle of at least 20 degrees. The first and second angles 2612a, 2612b need not be the same. In addition, the angles 2612a, 2612b need not be of opposite signs, but in some implementations, the angles will be of opposite signs with the same or different magnitudes.

[0287] In some embodiments, the SLM 2610 may tilt at a speed fast enough to avoid detection by the eye 210. For example, the SLM 260 may tilt between states (e.g., in a range of 5 - 15 degrees or greater or less) in less than 0.1 seconds, but should not be so limited. In some implementations, the tilt between states may occur within 200 milliseconds - 100 milliseconds, 100 milliseconds - 50 milliseconds, 100 milliseconds - 50 milliseconds, 50 milliseconds - 20 milliseconds, 50 milliseconds - 10 milliseconds, 40 milliseconds - 5 milliseconds, 30 milliseconds - 1 millisecond, or any range formed by any of these values.

[0288] As discussed above, a wide range of variations are possible. For example, the SLM 2610 may be configured to tilt in different directions. For example, in the embodiments shown in FIGS. 26A - 29B, the SLM is depicted as tilting about an axis 2615 parallel to the z - axis, but the SLM may rotate about a different axis or one or more axes. The SLM 2610 may, for example, tilt or rotate about an axis 2615 parallel to the x - axis. In such a configuration, the internal coupling optical elements may be arranged on the opposite side of the light source corresponding to different positions spaced laterally along the z - direction (instead of along the x - direction). Other orientations are also possible. For example, the SLM 2610 may rotate about an axis angled at 45° with respect to the x and z axes. Similarly, the SLM 2610 may be configured to rotate about an axis 2615 having other angular orientations.

[0289] Various types of light sources may be employed. U.S. Provisional Patent Application No. 62 / 686,474, filed on June 18, 2018, and titled "RGB ILLUMINATOR SYSTEM HAVING CURVED SURFACES" (which is hereby incorporated by reference in its entirety herein), discloses some exemplary light source configurations as shown in FIGS. 7 and 8. However, other configurations and other types of light sources may also be employed.

[0290] For example, such a configuration as described herein may be used in combination with a design that includes a plurality of internal coupling gratings and / or a plurality of pupil expanders such as an orthogonal pupil expander. Some examples of eyepiece designs that may be used in combination with the configuration described herein are presented in U.S. Patent Application Publication No. 2018 / 0275411, published on September 27, 2018, corresponding to U.S. Patent Application No. 15 / 927,821, filed on March 21, 2018, and titled "Method and System for Waveguide Projection with Wide Field of View" (which is hereby incorporated by reference in its entirety herein). However, other configurations may also be employed.

[0291] In various designs, the spatial light modulator array includes a reflective spatial light modulator array that modulates the light reflected therefrom. In some implementations, the spatial light modulator array may include a liquid crystal spatial light modulator array. In some implementations, the spatial light modulator array may include a movable micromirror array such as a digital micromirror device (DMD) array.

[0292] Also, eyepieces of various different configurations are also conceivable as possibilities. For example, in various implementations (such as in FIGS. 26C, 29B, and 30B, etc.), the external coupling optical element 1180 is shown to be separate from the light dispersing element or orthogonal pupil expander (OPE) 1170, but other configurations are also conceivable as possibilities. For example, the functionality of the light dispersing element or orthogonal pupil expander (OPE) 1170 of the external coupling optical element 1180 can be combined, for example, in a single diffractive optical element or grating in some designs. Additionally, waveguides in any order may be included in the waveguide stack. For example, the upper waveguide may output red light, or the bottom waveguide may output red light. Alternatively, the upper waveguide may output green light, or the bottom waveguide may output green light. Similarly, the upper waveguide may output blue light, or the bottom waveguide may output blue light. Any other order is also conceivable as a possibility. Also, as discussed above, other colors may be used.

[0293] The term In particular, conditional terms used herein such as "can", "could", "might", "may", "e.g.", and equivalents, generally convey that one embodiment includes a certain feature, element, and / or step while another embodiment does not, unless specifically described otherwise or understood otherwise within the context in which they are used. Thus, such conditional terms are not generally intended to imply that a feature, element, and / or step is required in any way for one or more embodiments, or that one or more embodiments necessarily include logic for determining whether these features, elements, and / or steps should be included in or implemented in any particular embodiment, regardless of the author's input or prompt. The terms "comprising", "including", "having", and equivalents are synonyms and are used inclusively in a non-limiting manner, without excluding additional elements, features, acts, operations, etc. Also, the term "or", when used, is used in its inclusive sense (and not in its exclusive sense) to mean one, several, or all of the elements in a list connected by the term "or". Additionally, the articles "a", "an", and "the" as used in this application and the appended claims are to be construed to mean "one or more" or "at least one" unless otherwise defined. Additionally, the articles "a", "an", and "the" as used in this application and the appended claims are to be construed to mean "one or more" or "at least one" unless otherwise defined. Similarly, operations may be depicted in the drawings in a particular order, but it should be recognized that such operations need not be performed in the particular order shown or in a sequential order, or that all of the illustrated operations need to be performed, in order to achieve the desired result. Further, the drawings may schematically depict one or more exemplary processes in the form of flowcharts.However, other operations that are not depicted may also be incorporated within the illustrated exemplary methods and processes. For example, one or more additional operations may be performed before, after, concurrently with, or between any of the illustrated operations. Additionally, the operations may be rearranged or reordered in other embodiments. In some situations, multitasking and parallel processing may be advantageous. Further, the separation of the various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired results.

[0294] Accordingly, the claims are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the disclosure, principles, and novel features disclosed herein.

Claims

[Claim 1] Display systems, methods, etc.

Images