Display system having optical elements for intercombining multiplexed light streams - Patents.com

Abstract

To provide virtual reality and augmented reality imaging and visualization systems.SOLUTION: Architectures are provided for selectively incoupling one or more streams of light from a multiplexed light stream into a waveguide. The multiplexed light stream can have light with different characteristics (e.g., different wavelengths and / or different polarizations). The waveguide can comprise in-coupling elements that can selectively couple one or more streams of light from the multiplexed light stream into the waveguide while transmitting one or more other streams of light from the multiplexed light stream.SELECTED DRAWING: None

Description

[Technical field]

[0001] (Priority Claim) This application claims the benefit of priority under §119(e) of U.S. Provisional Patent Application No. 62 / 175,994, filed June 15, 2015, and U.S. Provisional Patent Application No. 62 / 180,551, filed June 16, 2015, each of which is incorporated herein by reference in its entirety.

[0002] (Incorporated by reference) This application incorporates by reference the entirety of the following U.S. patents and patent applications: U.S. Patent No. 6,334,960, issued January 1, 2002 and entitled "Step and Flash Imprint Technology," U.S. Patent No. 6,873,087, issued March 29, 2005 and entitled "High-Precision Orientation, Alignment and Gap control Stages for Imprint Lithography Processes," U.S. Patent No. 6,900,881, issued May 31, 2005 and entitled "Step and Repeat Imprint Lithography," U.S. Patent No. 7,070,405, issued July 4, 2006 and entitled "Alignment Systems for Imprint Lithography," U.S. Patent No. 7,122,482, issued October 17, 2006 and entitled "Methods for Fabricating Patterned Features Utilizing Imprint No. 7,140,861 issued on November 28, 2006 (titled "Compliant Hard Template for UV Imprinting"), U.S. Patent No. 8,076,386 issued on December 13, 2011 (titled "Materials for Imprint Lithography"), U.S. Patent No. 7,098,572 issued on August 29, 2006 (titled "Apparatus to Control Displacement of a Body Spaced Apart from a No. 14 / 690,401, filed April 18, 2015; U.S. Patent Application No. 14 / 212,961, filed March 14, 2014; and U.S. Patent Application No. 14 / 331,218, filed July 14, 2014.

[0003] (Field) The present disclosure relates to virtual reality and augmented reality imaging and visualization systems. [Background technology]

[0004] Description of Related Art Modern computing and display technologies have facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally reproduced images or portions thereof are presented to a user in a manner that appears or can be perceived as real. Virtual reality (or "VR") scenarios typically involve the presentation of digital or virtual image information without transparency to other actual real-world visual inputs, while augmented reality (or "AR") scenarios typically involve the presentation of digital or virtual image information as an augmentation to the visualization of the real world around the user. For example, referring to FIG. 1, an augmented reality scene (1) is depicted in which a user of the AR technology sees a real-world park-like setting (6) featuring people, trees, and buildings in the background, and a concrete platform (1120). In addition to these items, a user of the AR technology also perceives as "seeing" a robotic figure (1110) standing on the real-world platform (1120) and a flying, cartoon-like avatar character (2) that appears to be an anthropomorphic bumblebee, although these elements (2, 1110) do not exist in the real world. Because of the complexity of the human visual perception system, it is challenging to create VR or AR technology that facilitates a comfortable, natural-feeling, and rich presentation of virtual image elements among other virtual or real-world image elements.

[0005] The systems and methods disclosed herein address various challenges associated with VR or AR technology. Summary of the Invention [Means for solving the problem]

[0006] The systems, methods, and devices of the present disclosure each have several innovative aspects, none of which is solely responsible for the desirable attributes disclosed herein.

[0007] In some embodiments, a display system is provided. The display system includes a waveguide and an image input device configured to direct a multiplexed light stream into the waveguide. The multiplexed light stream includes a plurality of light streams having different optical properties. The waveguide includes an in-coupling optical element configured to selectively in-couple a first one of the light streams while being transparent to one or more other light streams. In some embodiments, the waveguide is part of a stack of waveguides, which can include a second waveguide including an in-coupling optical element configured to selectively redirect a second one of the light streams while being transparent to one or more other light streams. In some embodiments, the in-coupling optical element of the waveguide is configured to transmit at least one of the light streams to the in-coupling optical element of the second waveguide.

[0008] Various methods of fabricating liquid crystal devices are described herein, including jet depositing liquid crystal material onto a substrate and aligning the molecules of the liquid crystal using imprint patterns. Using the methods described herein, devices including one or several layers of liquid crystal material can be fabricated. Liquid crystal devices fabricated using the methods described herein can include liquid crystal gratings, including features and / or patterns having sizes less than about a few microns. Liquid crystal devices fabricated using the methods described herein can also include what are referred to as Pancharatnam-Berry Phase Effect (PBPE) structures, metasurfaces, or metamaterials, which can include liquid crystal features and / or patterns having sizes less than the wavelength of visible light. In some cases, the small patterned features in these structures can be about 10 nm to about 100 nm wide and about 100 nm to about 1 micron high. In some cases, the small patterned features in these structures can be about 10 nm to about 1 micron wide and about 10 nm to about 1 micron high. Structures for manipulating light, such as beam steering, wavefront shaping, wavelength and / or polarization separation, and combination of different wavelengths and / or polarizations, can include liquid crystal gratings with metasurfaces, otherwise referred to herein as metamaterial liquid crystal gratings, or liquid crystal gratings with Pancharatnam-Berry Phase Effect (PBPE) structures. Liquid crystal gratings with PBPE structures can combine the high diffraction efficiency and low sensitivity to incidence angle of liquid crystal gratings with the high wavelength sensitivity of PBPE structures. Using the various methods of fabrication described herein, liquid crystal gratings with PBPE structures can be mass-produced, which may not be possible using existing methods of depositing PBPE structures onto liquid crystal materials. The methods discussed herein can also be used to fabricate polarizers that are more transparent than existing polarizers.

[0009] Innovative aspects of the subject matter disclosed herein include a display system comprising a waveguide and an image injection device configured to direct a multiplexed light stream into the waveguide. The multiplexed light stream provided by the image injection device can comprise a plurality of light streams having different optical properties. The waveguide comprises an internal coupling optical element configured to selectively internally couple a first one of the light streams while being transparent to one or more other light streams. The internal coupling optical element can comprise at least one of a diffractive structure, a liquid crystal material, a metasurface, a metamaterial, a PBPE structure, a liquid crystal polarization grating with a PBPE structure, or a liquid crystal polarization grating with a metasurface. The internal coupling optical element can be switchable between a transmissive state and an active light redirecting state. Various embodiments of the waveguide can be included within an eyepiece of a head mounted display.

[0010] In various embodiments of the display system, the waveguide can be part of a stack of waveguides. The stack of waveguides can include a second waveguide with an in-coupling optical element that can be configured to selectively redirect a second of the light flows while being transparent to one or more other light flows. In such embodiments, the in-coupling optical element of the waveguide can be configured to transmit at least one of the light flows to the in-coupling optical element of the second waveguide.

[0011] The light streams can have different wavelengths, different polarizations, or a combination thereof. In various embodiments, the image input device can be configured to provide all of the light streams of the multiple light streams to the waveguide simultaneously. In various embodiments, the image input device can be configured to provide at least some of the light streams of the multiple light streams to the waveguide at different times. The image input device can be a scanning optical fiber. In various embodiments, the image input device can comprise a light modulation device.

[0012] In various embodiments, the waveguide and / or the second waveguide can comprise an external coupling element configured to output the internally coupled first light flow propagating within the waveguide. The external coupling element can comprise a first group of light redirecting elements configured to increase a dimension of the eyebox along at least one axis. The external coupling element can further comprise a second group of light redirecting elements configured to increase a dimension of the eyebox along an axis orthogonal to the at least one axis.

[0013] Another innovative aspect of the subject matter disclosed herein includes a display system comprising a plurality of stacked waveguides and an image input device. The image input device is configured to direct a multiplexed light stream into the plurality of stacked waveguides. The multiplexed light stream comprises a plurality of light streams having different optical properties. Each waveguide in the plurality of stacked waveguides comprises an in-coupling optical element. Each waveguide is configured to selectively in-couple one or more of the plurality of light streams while being transparent to one or more others of the plurality of light streams. The plurality of stacked waveguides can be included in an eyepiece of a head mounted display. Each waveguide comprises an out-coupling element configured to output one or more of the in-coupled plurality of light streams propagating in the waveguide.

[0014] The internal coupling optical element can comprise at least one of a diffractive structure, a liquid crystal material, a metasurface, a metamaterial, a PBPE structure, a liquid crystal polarization grating comprising a PBPE structure, or a liquid crystal polarization grating comprising a metasurface. In various embodiments, the internal coupling optical element can be switchable between a transmissive state and an active light redirecting state. The different light characteristics can have different wavelengths, different polarizations, or a combination thereof. The image injection device can be configured to provide all of the light streams of the plurality of light streams to the waveguide simultaneously. The image injection device can be configured to provide at least some of the light streams of the plurality of light streams to the waveguide at different times. In various embodiments, the image injection device can be a scanning optical fiber. In some embodiments, the image injection device can comprise a light modulation device.

[0015] Innovative aspects of the subject matter disclosed herein include a display system comprising a waveguide and an image input device configured to direct a multiplexed light stream into the waveguide. The multiplexed light stream can comprise a plurality of light streams having different optical properties. The waveguide comprises a first incoupling optical element configured to selectively incoupling a first one of the light streams while being transparent to one or more other light streams. In some embodiments, the waveguide can comprise a second incoupling optical element configured to selectively incoupling a second one of the light streams while being transparent to one or more other light streams. In some other embodiments, the waveguide can comprise a third incoupling optical element configured to selectively incoupling a third one of the light streams while being transparent to one or more other light streams. In various embodiments, the first, second, or third incoupling optical element can include a liquid crystal layer comprising a metasurface. Various embodiments of the waveguide can be included within an eyepiece of a head mounted display.

[0016] The details of one or more embodiments of the subject matter described herein are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. Please note that the relative dimensions of the following figures may not be drawn to scale. The present invention provides, for example: (Item 1) 1. A display system comprising: A waveguide; an image input device configured to direct a multiplexed light stream into the waveguide, the multiplexed light stream comprising a plurality of light streams having different optical characteristics; and wherein the waveguide comprises an incoupling optical element configured to selectively incoupling a first one of the light flows while being transparent to one or more other light flows. (Item 2) Item 2. The system of item 1, wherein the waveguide is part of a stack of waveguides, the stack of waveguides including a second waveguide comprising an internal coupling optical element configured to selectively redirect a second of the light flows while being transparent to one or more other light flows, the internal coupling optical element of the waveguide configured to transmit at least one of the light flows to the internal coupling optical element of the second waveguide. (Item 3) Item 2. The system of item 1, wherein the internal coupling optical element is a diffractive structure. (Item 4) Item 1 , the internal coupling optical element comprising a liquid crystal material. (Item 5) Item 1, wherein the internal coupling optical element is switchable between a transmissive state and an active light redirecting state. (Item 6) Item 2. The system of item 1, wherein the internal coupling optical element comprises a metasurface. (Item 7) Item 1, the internal coupling optical element comprises a metamaterial. (Item 8) Item 2. The system of item 1, wherein the internal coupling optical element comprises a PBPE structure. (Item 9) Item 1. The system of item 1, wherein the light streams have different wavelengths, different polarizations, or a combination thereof. (Item 10) 2. The system of claim 1, wherein the image input device is configured to provide all of the plurality of light streams to the waveguide simultaneously. (Item 11) 2. The system of claim 1, wherein the image input device is configured to provide at least some of the light streams of the plurality of light streams to the waveguide at different times. (Item 12) Item 2. The system of item 1, wherein the image input device is a scanning optical fiber. (Item 13) Item 1 , the system comprising: a light modulation device. (Item 14) Item 2. The system of item 1, wherein the waveguide is contained within an eyepiece of a head mounted display. (Item 15) Item 2. The system of item 1, wherein the waveguide comprises an outcoupling element configured to output the incoupling first light stream propagating within the waveguide. (Item 16) Item 16. The system of item 15, wherein the external coupling element comprises a first group of light redirecting elements configured to increase a dimension of an eyebox along at least one axis. (Item 17) Item 17. The system of item 16, wherein the external coupling element comprises a second group of light redirecting elements configured to increase a dimension of the eyebox along an axis orthogonal to the at least one axis. (Item 18) Item 1. The system of item 1, wherein the internal coupling optical element comprises a liquid crystal polarization grating having a PBPE structure. (Item 19) Item 2. The system of item 1, wherein the internal coupling optical element comprises a liquid crystal polarization grating comprising a metasurface. (Item 20) 1. A display system comprising: a plurality of stacked waveguides, each waveguide comprising an incoupling optical element; an image input device configured to direct a multiplexed light stream into the plurality of stacked waveguides, the multiplexed light stream comprising a plurality of light streams having different optical characteristics; and wherein each waveguide is configured to selectively in-couple one or more of the plurality of light streams while being transparent to one or more others of the plurality of light streams. (Item 21) 21. The system of claim 20, wherein the internal coupling optical element is a diffractive structure. (Item 22) 21. The system of claim 20, wherein the internal coupling optical element comprises a liquid crystal material. (Item 23) Item 21. The system of item 20, wherein the internal coupling optical element is switchable between a transmissive state and an active light redirecting state. (Item 24) 21. The system of claim 20, wherein the internal coupling optical element comprises a metasurface. (Item 25) 21. The system of claim 20, wherein the incoupling optical element comprises a metamaterial. (Item 26) 21. The system of claim 20, wherein the internal coupling optical element comprises a PBPE structure. (Item 27) 21. The system of claim 20, wherein the internal coupling optical element comprises a liquid crystal polarization grating comprising a PBPE structure. (Item 28) 21. The system of claim 20, wherein the internal coupling optical element comprises a liquid crystal polarization grating comprising a metasurface. (Item 29) 21. The system of claim 20, wherein the different light characteristics comprise different wavelengths, different polarizations, or a combination thereof. (Item 30) 21. The system of claim 20, wherein the image input device is configured to provide all of the plurality of light streams to the waveguide simultaneously. (Item 31) 21. The system of claim 20, wherein the image input device is configured to provide at least some of the light streams of the plurality of light streams to the waveguide at different times. (Item 32) 21. The system of claim 20, wherein the image input device is a scanning optical fiber. (Item 33) 21. The system of claim 20, wherein the image input device comprises a light modulation device. (Item 34) 21. The system of claim 20, wherein the plurality of stacked waveguides are contained within an eyepiece of a head mounted display. (Item 35) 21. The system of claim 20, wherein each waveguide comprises an outcoupling element configured to output the incoupling one or more of the plurality of light streams propagating within the waveguide. (Item 36) 1. A display system comprising: A waveguide; an image input device configured to direct a multiplexed light stream into the waveguide, the multiplexed light stream comprising a plurality of light streams having different optical characteristics; and Equipped with the waveguide comprises a first incoupling optical element configured to selectively incoupling a first of the light streams while being transparent to one or more other light streams; The first internal coupling optical element includes a liquid crystal layer having a metasurface. Display system. (Item 37) Item 37. The display system of item 36, further comprising a second incoupling optical element configured to selectively incoupling a second of the light streams while being transparent to one or more other light streams, the second incoupling optical element comprising a layer of liquid crystal comprising a metasurface. (Item 38) Item 38. The display system of item 37, wherein the second incoupling optical element is disposed across the first incoupling optical element. (Item 39) Item 37. The display system of item 36, further comprising a third incoupling optical element configured to selectively incoupling a third of the light streams while being transparent to one or more other light streams, the third incoupling optical element comprising a layer of liquid crystal comprising a metasurface. (Item 40) 40. The display system of claim 39, wherein the third incoupling optical element is disposed across the second incoupling optical element. (Item 41) Item 37. The display system of item 36, wherein the waveguide is contained within an eyepiece of a head mounted display. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 illustrates a user's view of an augmented reality (AR) device.

[0018] [Diagram 2] FIG. 2 illustrates an embodiment of a wearable display system.

[0019] [Diagram 3] FIG. 3 illustrates a conventional display system for simulating a three-dimensional image for a user.

[0020] [Figure 4] FIG. 4 illustrates aspects of an approach for simulating a three-dimensional image using multiple depth planes.

[0021] [Diagram 5] 5A-5C illustrate the relationship between the radius of curvature and the radius of focus.

[0022] [Figure 6] FIG. 6 illustrates an embodiment of a waveguide stack for outputting image information to a user.

[0023] [Figure 7] FIG. 7 shows an example of an output beam output by a waveguide.

[0024] [Figure 8A] FIG. 8A illustrates generally a perspective view of an example of delivery of multiplexed image information into one or more waveguides.

[0025] [Figure 8B] FIG. 8B illustrates generally a perspective view of another embodiment of delivery of multiplexed image information into multiple waveguides.

[0026] [Figure 8C] FIG. 8C illustrates a schematic top-down view of the display system of FIG. 8B.

[0027] [Figure 8D] FIG. 8D illustrates the display system of FIG. 8C with light redirecting elements for outcoupling light from each waveguide.

[0028] [Figure 8E] FIG. 8E illustrates the display system of FIG. 8B including an image input device comprising a light modulation device for providing xy pixel information.

[0029] [Figure 9A] FIG. 9A illustrates an embodiment of a method for fabricating a liquid crystal device.

[0030] [Figure 9B] 9B and 9C illustrate embodiments of imprint templates that may be used to fabricate a liquid crystal device according to the methods described in FIG. 9A above or FIG. 9D below. [Figure 9C] 9B and 9C illustrate embodiments of imprint templates that may be used to fabricate a liquid crystal device according to the methods described in FIG. 9A above or FIG. 9D below.

[0031] [Figure 9D] FIG. 9D illustrates another embodiment of a method for fabricating a liquid crystal device.

[0032] [Figure 9E] 9E, 9F, 9G, and 9H illustrate various embodiments of liquid crystal devices that can be manufactured using the methods described in FIG. 9A or 9D. [Figure 9F] 9E, 9F, 9G, and 9H illustrate various embodiments of liquid crystal devices that can be manufactured using the methods described in FIG. 9A or 9D. [Figure 9G] 9E, 9F, 9G, and 9H illustrate various embodiments of liquid crystal devices that can be manufactured using the methods described in FIG. 9A or 9D. [Figure 9H] 9E, 9F, 9G, and 9H illustrate various embodiments of liquid crystal devices that can be manufactured using the methods described in FIG. 9A or 9D.

[0033] [Figure 9I] FIG. 9I illustrates an embodiment of a resist layer that is imprinted with a pattern as illustrated in the method illustrated in FIG. 9D.

[0034] [Figure 9J]Figure 9J illustrates a first imprint structure having separate droplets or sections oriented along a first direction and a second imprint structure having separate droplets or sections oriented along a second direction, which may be combined to produce an optical device with a composite grating pattern.

[0035] [Figure 9K] 9K and 9L illustrate different polarizer configurations that can be fabricated using the jet deposition and imprinting methods described herein. [Figure 9L] 9K and 9L illustrate different polarizer configurations that can be fabricated using the jet deposition and imprinting methods described herein.

[0036] [Figure 9M] FIG. 9M illustrates an embodiment of a waveguide plate having optical entrance and exit surfaces that can change the polarization state of incident light.

[0037] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] (Detailed Description) The embodiments disclosed herein generally include an optical system including a display system. In some embodiments, the display system is wearable, which may advantageously provide a more immersive VR or AR experience. For example, a display including a stack of waveguides may be configured to be worn and positioned in front of the eyes of a user or viewer. In some embodiments, two stacks of waveguides, one for each eye of the viewer, may be utilized to provide a different image to each eye.

[0039] 2 illustrates an example of a wearable display system (80). The display system (80) includes a display (62) and various mechanical and electronic modules and systems to support the functionality of the display (62). The display (62) may be coupled to a frame (64), which is wearable by a display system user or viewer (60) and configured to position the display (62) directly in front of the user's (60) eye. In some embodiments, a speaker (66) is coupled to the frame (64) and positioned adjacent the user's ear canal (in some embodiments, another speaker, not shown, is positioned adjacent the user's other ear canal to provide stereo / shapeable sound control). The display (62) is operatively coupled (68), such as by wired leads or wireless connectivity, to a local data processing module (70), which may be mounted in a variety of configurations, such as fixedly attached to the frame (64), fixedly attached to a helmet or hat worn by the user, embedded within headphones, or otherwise removably attached to the user (60) (e.g., in a backpack-type configuration, a belt-coupled configuration)).

[0040] The local processing and data module (70) may include a processor and digital memory, such as non-volatile memory (e.g., flash memory), both of which may be utilized to aid in processing, caching, and storing data. The data includes a) data captured from sensors (e.g., which may be operatively coupled to the frame (64) or otherwise attached to the user (60)), such as image capture devices (e.g., cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, wireless devices, and / or gyroscopes, and / or b) data acquired and / or processed using the remote processing module (72) and / or remote data repository (74) for possible passing to the display (62) after processing or retrieval. The local processing and data module (70) may be operatively coupled to the remote processing module (72) and the remote data repository (74) by communications links (76, 78) (e.g., via wired or wireless communication links) such that these remote modules (72, 74) are operatively coupled to each other and available as resources to the local processing and data module (70).

[0041] In some embodiments, the remote processing module (72) may comprise one or more processors configured to analyze and process the data and / or image information. In some embodiments, the remote data repository (74) may comprise a digital data storage facility, which may be available through the Internet or other networking configurations in a "cloud" resource configuration. In some embodiments, all data is stored and all calculations are performed within the local processing and data module, allowing for fully autonomous use from the remote module.

[0042] The perception of an image as "three-dimensional" or "3-D" may be achieved by providing a slightly different presentation of the image to each eye of the viewer. FIG. 3 illustrates a conventional display system for simulating a three-dimensional image for a user. Two separate images 74 and 76, one for each eye 4 and 6, are output to the user. The images 74 and 76 are spaced apart from the eyes 4 and 6 by a distance 10 along an optical axis or z-axis parallel to the viewer's line of sight. The images 74 and 76 are flat, and the eyes 4 and 6 may focus on the images by assuming a single accommodated state. Such a system relies on the human visual system to combine the images 74 and 76 to provide the perception of depth of the combined image.

[0043] However, it should be appreciated that the human visual system is more complex and providing a realistic perception of depth is more difficult. For example, many viewers of conventional "3-D" display systems may find such systems uncomfortable or may not perceive any sense of depth at all. Without being limited by theory, it is believed that a viewer of an object may perceive the object as "three-dimensional" due to a combination of vergence and accommodation. Vergence movement of the two eyes relative to each other (i.e., the rolling movement of the pupils toward or away from each other to converge and fixate the gaze of the eyes on an object) is closely associated with focusing (or "accommodation") the lenses of the eyes. Under normal conditions, changing the focus of the lenses of the eyes, or accommodating the eyes to change focus from one object to another at a different distance, automatically produces a matching change in vergence to the same distance, under a relationship known as the "accommodation-vergence reflex." Similarly, changes in vergence induce matching changes in accommodation under normal conditions. As described herein, many stereoscopic or "3-D" display systems display a scene using slightly different presentations (and therefore slightly different images) to each eye so that a three-dimensional perspective is perceived by the human visual system. However, such systems are uncomfortable for many viewers, especially since they simply provide different presentations of the scene but work against the "accommodation-vergence reflex" when the eyes view the entire image information in a single accommodated state. Display systems that provide better matching between accommodation and vergence can create a more realistic and comfortable simulation of a three-dimensional image.

[0044] FIG. 4 illustrates aspects of an approach for simulating a three-dimensional image using multiple depth planes. With reference to FIG. 4A, objects at various distances from eyes 4 and 6 on the z-axis are accommodated by eyes (4, 6) to focus on those objects. Eyes 4 and 6 focus on objects at different distances along the z-axis by adopting a particular accommodated state. As a result, a particular accommodated state can be said to be associated with a particular one of the depth planes (14) such that an object or part of an object at a particular depth plane is focused on when the eye is in an accommodated state for that depth plane. In some embodiments, a three-dimensional image may be simulated by providing different presentations of images for each eye (4, 6) and by providing different presentations of images corresponding to each of the depth planes.

[0045] The distance between an object and an eye (4 or 6) can change the amount of divergence of light from that object viewed by that eye. Figures 5A-5C illustrate the relationship between distance and divergence of light rays. The distance between an object and the eye (4) is represented in the order of decreasing distances R1, R2, and R3. As shown in Figures 5A-5C, the light rays become more divergent as the distance to the object decreases. As the distance increases, the light rays become more collimated. In other words, the light field generated by a point (an object or part of an object) can be said to have a spherical wavefront curvature that is a function of the distance the point is away from the user's eye. The curvature increases with decreasing distance between the object and the eye (4). As a result, at different depth planes, the divergence of the light rays is also different, and the divergence increases with decreasing distance between the depth plane and the viewer's eye 4. Only a single eye (4) is illustrated in FIGS. 5A-5C and other figures herein for clarity of illustration, but it should be understood that discussion regarding eye (4) may apply to both eyes (4 and 6) of a viewer.

[0046] Without being limited by theory, it is believed that the human eye is typically capable of providing depth perception by interpreting a finite number of depth planes, such that a highly realistic simulation of perceived depth can be achieved by providing the eye with different presentations of images corresponding to each of these limited number of depth planes.

[0047] FIG. 6 illustrates an example of a waveguide stack for outputting image information to a user. The display system 1000 includes a stack of waveguides or a stacked waveguide assembly (178) that can be utilized to provide a three-dimensional perception to the eye / brain using multiple waveguides (182, 184, 186, 188, 190). In some embodiments, the display system (1000) is the system (80) of FIG. 2, and FIG. 6 shows several portions of the system (80) in more detail diagrammatically. For example, the waveguide assembly (178) may be integrated into the display (62) of FIG. 2.

[0048] Continuing with reference to FIG. 6, the waveguide assembly (178) may also include a number of features (198, 196, 194, 192) between the waveguides. In some embodiments, the features (198, 196, 194, 192) may be lenses. The waveguides (182, 184, 186, 188, 190) and / or the number of lenses (198, 196, 194, 192) may be configured to transmit image information to the eye with various levels of wavefront curvature or light beam 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. The image input devices (200, 202, 204, 206, 208) may be utilized to input image information into the waveguides (182, 184, 186, 188, 190), and each of the image input devices may be configured to distribute incident light across each individual waveguide for output toward the eye 4, as described herein. Light exits output surfaces (300, 302, 304, 306, 308) of the image input devices (200, 202, 204, 206, 208) and is input into corresponding input edges (382, 384, 386, 388, 390) of the waveguides (182, 184, 186, 188, 190). In some embodiments, a single beam of light (e.g., a collimated beam) may be launched into each waveguide, outputting a full field of cloned collimated beams that are directed towards the eye (4) at a particular angle (and divergence) corresponding to the depth plane associated with the particular waveguide.

[0049] In some embodiments, the image input devices (200, 202, 204, 206, 208) are each separate displays that generate image information for input into a corresponding waveguide (182, 184, 186, 188, 190, respectively). In some other embodiments, the image input devices (200, 202, 204, 206, 208) are the output of a single multiplexed display that may, for example, send image information to each of the image input devices (200, 202, 204, 206, 208) via one or more optical conduits (e.g., fiber optic cables).

[0050] The controller 210 controls the operation of the stacked waveguide assembly (178) and the image input devices (200, 202, 204, 206, 208). In some embodiments, the controller 210 includes programming (e.g., instructions in a non-transitory medium) that coordinates the timing and amount of image information provided to the waveguides (182, 184, 186, 188, 190), 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 wired or wireless communication channels. The controller 210 may be part of the processing module (70 or 72) (FIG. 2) in some embodiments.

[0051] The waveguides (182, 184, 186, 188, 190) may be configured to propagate light within each individual waveguide by total internal reflection (TIR). The waveguides (182, 184, 186, 188, 190) may each be planar, with major top and bottom surfaces and edges extending between the major top and bottom surfaces. In the illustrated configuration, the waveguides (182, 184, 186, 188, 190) may each include a light redirecting element (282, 284, 286, 288, 290) configured to redirect light propagating within each individual waveguide out of the waveguide and output image information to the eye 4. A beam of light is output by the waveguide where the light propagating within the waveguide strikes the light redirecting element. The light redirecting elements (282, 284, 286, 288, 290) may be reflective and / or diffractive optical features. Although shown disposed on the bottom major surface of the waveguides (182, 184, 186, 188, 190) for ease of explanation and clarity of the drawings, in some embodiments the light redirecting elements (282, 284, 286, 288, 290) may be disposed on the top and / or bottom major surfaces and / or directly within the volume of the waveguides (182, 184, 186, 188, 190). In some embodiments, the light redirecting elements (282, 284, 286, 288, 290) may be formed within a layer of material that is attached to a transparent substrate to form the waveguides (182, 184, 186, 188, 190). In some other embodiments, the waveguides (182, 184, 186, 188, 190) may be a monolithic piece of material and the light redirecting elements (282, 284, 286, 288, 290) may be formed on a surface of and / or within that piece of material.

[0052] With continued reference to FIG. 6, as discussed herein, each waveguide (182, 184, 186, 188, 190) is configured to output light and form an image corresponding to a particular depth plane. For example, the waveguide (182) closest to the eye may be configured to deliver collimated light injected into such waveguide (182) to the eye (4). The collimated light may represent an optical infinity focal plane. The next upper waveguide (184) may be configured to send collimated light that passes through a first lens (192; e.g., a negative lens) before it can reach the eye (4). Such first lens (192) may be configured to generate a slight convex wavefront curvature such that the eye / brain interprets the light originating from the next upper waveguide (184) as originating from a first focal plane closer inward from optical infinity toward the eye (4). Similarly, the third upper waveguide (186) passes its output light through both the first lens (192) and the second lens (194) before reaching the eye (4). The combined refractive powers of the first lens (192) and the second lens (194) may be configured to produce another incremental amount of wavefront curvature such that the eye / brain interprets the light emerging from the third waveguide (186) as originating from a second focal plane that is closer inward from optical infinity towards the person than the light from the next upper waveguide (184).

[0053] The other waveguide layers (188, 190) and lenses (196, 198) are similarly configured, with the highest waveguide (190) in the stack sending its output through all of the lenses between it and the eye for an aggregate focal power that represents the focal plane closest to the person. To compensate the stack of lenses (198, 196, 194, 192) when viewing / interpreting light originating from the world (144) on the other side of the stacked waveguide assembly (178), a compensating lens layer (180) may be placed on top of the stack to compensate for the aggregate power of the lower lens stacks (198, 196, 194, 192). Such a configuration provides as many perceived focal planes as there are available waveguide / lens pairs. Both the light redirecting elements of the waveguides and the focusing sides of the lenses may be static (i.e., not dynamic or electroactive). In some alternative embodiments, they may be dynamic using electroactive features.

[0054] Continuing with reference to FIG. 6, the light redirecting elements (282, 284, 286, 288, 290) may be configured to redirect light from its respective waveguide 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 with different associated depth planes may have different configurations of light redirecting elements (282, 284, 286, 288, 290) that output light with different amounts of divergence depending on the associated depth plane. In some embodiments, as discussed herein, the light redirecting elements (282, 284, 286, 288, 290) may be volume or surface features that may be configured to output light at a particular angle. For example, the light redirecting elements (282, 284, 286, 288, 290) may be volume holograms, surface holograms, and / or diffraction gratings. Light redirecting elements such as diffraction gratings are described in U.S. Patent Application Serial No. 14 / 641,376, filed March 7, 2015, which is incorporated by reference in its entirety. In some embodiments, the features (198, 196, 194, 192) may not be lenses. Rather, they may simply be spacers (e.g., cladding layers and / or structures for forming air gaps).

[0055] In some embodiments, the light redirecting elements (282, 284, 286, 288, 290) are diffractive features that form a diffraction pattern or "diffractive optical element" (also referred to herein as "DOE"). Preferably, the DOE has a relatively low diffraction efficiency so that only a portion of the light of the beam is refracted toward the eye (4) with each intersection point of the DOE, while the remainder continues traveling through the waveguide via total internal reflection. The light carrying the image information is thus split into several related output beams that exit the waveguide at various locations, resulting in a very uniform pattern of output emission toward the eye (4) for this particular collimated beam bouncing within the waveguide.

[0056] In some embodiments, one or more DOEs may be switchable between an "on" state in which they actively diffract and an "off" state in which they do not significantly diffract. For example, a switchable DOE may comprise a layer of polymer dispersed liquid crystal in which microdroplets comprise a diffractive pattern in a host medium, and the refractive index of the microdroplets can be switched to substantially match the refractive index of the host material (in which case the pattern does not significantly diffract incident light), or the microdroplets can be switched to a refractive index that does not match that of the host medium (in which case the pattern actively diffracts incident light).

[0057] FIG. 7 shows an example of an output beam output by a waveguide. Although one waveguide is shown, it should be understood that other waveguides in the stack of waveguides (178) may function similarly. Light (400) is launched into the waveguide (182) at the input edge (382) of the waveguide (182) and propagates within the waveguide (182) by TIR. At the point where the light (400) impinges on the DOE (282), a portion of the light exits the waveguide as an output beam (402). The output beam (402) is shown as substantially parallel, but as discussed herein, the output beam (402) may also be redirected to propagate to the eye (4) at an angle (e.g., to form a diverging output beam) depending on the depth plane associated with the waveguide (182). It should be understood that a nearly collimated exit beam may represent a waveguide that corresponds to a depth plane at a large distance (e.g., optical infinity) from the eye (4). Other waveguides may output a more divergent exit beam pattern, which requires the eye (4) to accommodate to a closer distance to focus on the retina, and is interpreted by the brain as light from a distance closer to the eye (4) than optical infinity.

[0058] (Part I. Multiplexed Image Information) 6, utilizing a dedicated image input device (200, 202, 204, 206, or 208) for each waveguide (182, 184, 186, 188, or 190) may be mechanically complex and may require a large volume to accommodate the image input device and all of its associated connections. A smaller form factor may be desirable for some applications, such as wearable displays.

[0059] In some embodiments, a smaller form factor may be achieved by using a single image input device and injecting information into multiple waveguides. The image input device delivers multiple image information streams (also referred to herein as information streams) to the waveguides, which may be considered to be multiplexed. Each waveguide includes an internal coupling optical element that interacts with the information streams to selectively in-couple image information from a particular information stream into that waveguide. In some embodiments, the internal coupling optical element selectively redirects light from a particular information stream into its associated waveguide while allowing light for other information streams to continue to propagate into other waveguides. The redirected light is redirected at an angle such that it propagates through its associated waveguide by TIR. Thus, in some embodiments, a single image input device provides a multiplexed information stream to multiple waveguides, each waveguide of the multiple waveguides having an associated information stream that is selectively in-coupled using an internal coupling optical element.

[0060] The selective interaction between the internal coupling optical element and the information streams may be facilitated by utilizing information streams with different optical properties. For example, each information stream may be formed by light of a different color (different wavelength) and / or different polarization (preferably different circular polarization). In turn, the internal coupling optical element is configured to selectively redirect light of a specific polarization and / or one or more specific wavelengths, thereby enabling a specific correspondence, e.g., a one-to-one correspondence between the information streams and the waveguides. In some embodiments, the internal coupling optical element is a diffractive optical element configured to selectively redirect light based on the properties of that light, e.g., the wavelength and / or polarization of that light.

[0061] In some embodiments, each image input device provides image information to more than one of the two, three, four, or more waveguides by providing two, three, four, or more information streams to the multiple waveguides, respectively. In some embodiments, multiple such image input devices may be used to provide information to each of the multiple waveguides.

[0062] 8A, an example of delivery of multiplexed image information into one or more waveguides is illustrated generally in a perspective view. Stack 3000 includes waveguides 3002 and 3004, which include incoupling optical elements 3012 and 3014, respectively. In some embodiments, waveguides 3002 and 3004 may be substantially planar plates, each having a front major surface and a back major surface and an edge extending between the front and back major surfaces. For example, waveguide 3002 has a front major surface 3002a and a back major surface 3002b. The major surfaces of the waveguides may include cladding layers (not shown) to promote TIR of light within each waveguide. In some embodiments, stack 3000 of waveguides corresponds to stack 178 of FIG. 6 and may be utilized to replace stack 178 in the display systems disclosed herein.

[0063] 8A , light streams A and B have different optical properties, e.g., different wavelengths and / or different polarizations (preferably different circular polarizations). Light streams A and B comprise separate image information streams. Light A and light B and their information streams are propagated as a multiplexed information stream through optical conduits 3024 (e.g., optical fibers) to image input device 3021. The image input device inputs light 3040 (including the multiplexed information stream as combined light streams A and B) into waveguide stack 3000.

[0064] In some embodiments, the image input device 3021 includes an actuator 3020 (such as a piezoelectric actuator) coupled to the optical fiber 352 that can be used to scan the fiber tip of the fiber 352 across the area of ​​the stack 3000. An example of such a scanning fiber image input device is disclosed in U.S. patent application Ser. No. 14 / 641,376, filed Mar. 7, 2015, which is incorporated by reference in its entirety. In some other embodiments, the image input device 3021 may be stationary, and in some embodiments may direct light toward the stack 3000 from multiple angles.

[0065] In some embodiments, each waveguide includes an in-coupling optical element. For example, waveguide 3002 includes an in-coupling optical element 3012, and waveguide 3004 includes an in-coupling optical element 3014. The in-coupling optical elements 3012 and 3014 are configured to selectively redirect one of light flow A and light flow B. For example, the in-coupling optical element 3012 may selectively redirect at least a portion of light flow A and in-couple that light flow into the optical waveguide 3002. The in-coupled portion of light flow A propagates through the waveguide 3002 as light 3042. In some embodiments, the light 3042 propagates through the waveguide 3002 by TIR from the major surfaces 3002a and 3002b of that waveguide. Similarly, the in-coupling optical element 3014 may selectively redirect at least a portion of light flow B and in-couple that light flow into the optical waveguide 3004. The internally coupled portion of light flow B propagates through waveguide 3004 as light 3044. In some embodiments, light 3044 propagates through waveguide 3004 by TIR from major surfaces 3004a and 3004b of the waveguide.

[0066] As shown, in some embodiments, the multiplexed light stream 3040 may include both light stream A and light stream B simultaneously, with light stream A being internally coupled to waveguide 3002 while light stream B is internally coupled to waveguide 3004, as discussed above. In some other embodiments, light stream A and light stream B may be provided to the waveguide stack 3000 at different times. In such embodiments, only a single waveguide may be utilized to receive these information streams, as discussed herein. In either case, light stream A and light stream B may be coupled to the optical conduit 3024 by an optical combiner 3050. In some embodiments, the optical combiner 3050 may combine light stream A and light stream B for propagation through the optical conduit 3024.

[0067] 8A , in some embodiments, the optical section 3030 may be disposed between the image input device 3021 and the in-coupling optical elements 3012 and 3014. The optical section 3030 may include, for example, a lens that facilitates directing light rays onto the various in-coupling optical elements 3012 and 3014, for example, by focusing the light onto the in-coupling optical elements 3012 and 3014. In some embodiments, the optical section is part of the image input device 3021, for example, a lens at an end of the image input device 3021. In some embodiments, the optical section 3030 may be omitted entirely.

[0068] It should be appreciated that the incoupling optical elements 3012 and 3014 are configured to selectively redirect light streams A and B based on one or more optical characteristics that differ between the light streams. For example, light stream A may have a different wavelength than light stream B, and the incoupling optical elements 3012 and 3014 may be configured to selectively redirect light based on the wavelength. Preferably, the different wavelengths correspond to different colors, which can improve the selectivity of the incoupling optical elements with respect to using different wavelengths of the same color.

[0069] In some embodiments, light stream A may have a different polarization than light stream B, and the incoupling optical elements 3012 and 3014 may be configured to selectively redirect the light based on the polarization. For example, the incoupling optical elements 3012 and 3014 may be configured to selectively redirect the light based on the polarization. In some embodiments, light streams A and B have different circular polarizations. In some embodiments, light streams A and B may have multiple differences in optical properties, including, for example, both different wavelengths and different polarizations.

[0070] In some embodiments, the internal coupling optical elements 3012 and 3014 are diffractive optical elements including a diffraction grating (e.g., a grating comprising liquid crystals, such as a liquid crystal polarization grating). In some embodiments, the optical elements may include a metasurface (e.g., comprising PBPE), such as a surface having a pattern with feature sizes on the order of nanometers or tens of nanometers. Examples of suitable internal coupling optical elements 3012 and 3014 include optical elements 2000b, 2000d (FIG. 9A) and the optical elements of FIGS. 9E-9H. Advantageously, such optical elements are highly efficient at selectively redirecting light of different polarizations and / or different wavelengths.

[0071] 8B, another example of the delivery of multiplexed image information into multiple waveguides is illustrated in a perspective view. It should be understood that stack 3000 can include more than two waveguides, for example, 4, 6, 8, 10, 12, or other numbers of waveguides, so long as image information can be properly provided through stack 3000 to the individual waveguides and to the user's eyes. The illustrated stack 3000 includes waveguides 3006 and 3008 in addition to waveguides 3002 and 3004. Waveguides 3006 and 3008 include internal coupling optical elements 3012 and 3014, respectively. In some embodiments, waveguides 3002, 3004, 3006, and 3008 can be similar, except for the internal coupling optical elements, which can each be configured to redirect and internally couple light having different optical characteristics. In some other embodiments, the internal coupling optical elements for multiple waveguides can be similar. It should be understood that all of the disclosure herein relating to FIG. 8A also applies to FIG. 8B, but the number of waveguides in FIG. 8B is greater than in FIG. 8A.

[0072] 8B, light streams A, B, C, and D have different optical properties, e.g., different wavelengths and / or different polarizations (preferably different circular polarizations). For example, light streams A, B, C, and D may each include light of different wavelengths. In some other embodiments, various combinations of different wavelengths and polarizations are possible. For example, A and B may have similar wavelengths and different polarizations, and C and D may have similar wavelengths and different polarizations, with A and B being different from C and D. Light streams A, B, C, and D are propagated as a multiplexed information stream through optical conduit 3024 to image input device 3021, which inputs multiplexed information stream light 3040 into waveguide stack 3000. As discussed herein, the multiplexed information stream may include all light streams simultaneously, or one or more of the light streams may be directed to stack 3000 at different times.

[0073] In some embodiments, each waveguide includes an incoupling optical element that selectively incoupling light into that waveguide. For example, waveguide 3002 may include incoupling optical element 3012 that is configured to incoupling light stream A into that waveguide such that light stream A propagates within that waveguide by TIR as light 3042, and waveguide 3004 may include incoupling optical element 3014 that is configured to incoupling light stream B into that waveguide such that light stream B propagates within that waveguide by TIR as light 3044. However, waveguide 3006 may include an internal coupling optical element 3016 configured to internally couple light flow C into the waveguide such that light flow C propagates within the waveguide as light 3046 by TIR, and waveguide 3008 may include an internal coupling optical element 3018 configured to internally couple light flow D into the waveguide such that light flow D propagates within the waveguide as light 3048 by TIR.

[0074] It should be understood that in some embodiments, a single light stream (e.g., light stream A, B, C, or D) may be incoupling into a single waveguide. In some other embodiments, multiple light streams may be incoupling into the same waveguide. Preferably, in such an arrangement, the light streams are incoupling at different times. In some embodiments, such time-separated incoupling may be achieved using an incoupling optical element that selectively redirects light based on different light characteristics (e.g., different wavelengths or different polarizations) while the image input device provides information streams for a particular waveguide at different times. For example, light streams A and B may both be incoupling into the waveguide 3002, and the incoupling optical element 3012 selectively incoupling light streams A and B while allowing light streams C and D to pass through, where light streams A and B provide light to the incoupling optical element 3012 at different times while simultaneously providing light streams C and / or D to the incoupling optical element 3012. It should be understood that one or more other waveguides may be similarly configured to internally couple multiple light streams thereto.

[0075] In some other embodiments, multiple light streams (e.g., light stream A and light stream B) may be provided simultaneously to an incoupling optical element (e.g., incoupling optical element 3012), which may be configured to change state to select between incoupling light stream A or incoupling light stream B. For example, in some embodiments, the incoupling optical element may be a lattice formed from a liquid crystal material disposed between electrodes (e.g., transparent electrodes such as ITO). The liquid crystal may change state (e.g., orientation) with application of a voltage potential, with one state configured to selectively incoupling one light stream (e.g., light stream A) and another state configured to be transparent to all light streams (e.g., both light streams A and B). In some embodiments, another layer of switchable liquid crystal material forming a different lattice may be provided between the electrodes, with one state configured to selectively incoupling a different light stream (e.g., light stream B) and another state configured to be transparent to all light streams (e.g., both light streams A and B). In some other embodiments, both types of liquid crystal material may be disposed at the same level but in different areas. The liquid crystal materials may be configured such that when one type of material is transparent to the light stream, the other type selectively incouples the light of a particular light stream, and vice versa.

[0076]

[0046] Referring now to Figure 8C, a top-down schematic view of the display system of Figure 8B is illustrated. The top-down view is looking down along the top edge of stack 3000 of Figure 8B. As shown, in some embodiments, portions of multiplexed light stream 3040 are selectively incoupled as incoupled light 3042, 3044, 3046, and 3048 into waveguides 3002, 3004, 3006, and 3008, respectively.

[0077] As discussed herein, the waveguides may include light redirecting elements (e.g., light redirecting elements (282, 284, 286, 288, 290)) that output or outcouple light propagated inside the waveguide, such that the outcoupled light propagates toward the viewer's eye 4 (FIG. 6). FIG. 8D illustrates the display system of FIG. 8C with light redirecting elements for outcoupling light from each waveguide. For example, waveguide 3002 includes outcoupling light redirecting element 3062, waveguide 3004 includes outcoupling light redirecting element 3064, waveguide 3006 includes outcoupling light redirecting element 3066, and waveguide 3008 includes outcoupling light redirecting element 3068. In some embodiments, the outcoupling light redirecting elements may include groups of different light redirecting elements, each functioning differently. For example, the external coupling light redirecting element 3062 may include a first group of light redirecting elements 3062a and a second group of light redirecting elements 3062b. For example, the light redirecting element 3062b may be an exit pupil expander (EPE; increasing the size of the eyebox in at least one axis), and the light redirecting element 3062a may be an orthogonal pupil expander (OPE; increasing the size of the eyebox in an axis, e.g., orthogonal, that intersects the axis of the EPE). EPEs and OPEs are disclosed in U.S. Provisional Patent Application No. 62 / 005,807, filed May 30, 2014, the entire disclosure of which is incorporated herein by reference.

[0078] It should be understood that an image is formed by the waveguide using an information stream with encoded xy pixel information. For example, different colored information streams may each indicate light intensity at a particular location on an xy grid that corresponds to the xy pixel information for the image. Without being limited by theory, it is also understood that matching of the information stream with the waveguide is achieved using properties of light and does not necessarily depend on the xy pixel information provided by that light. As a result, the xy pixel information may be encoded at any suitable location using any suitable device along the path of the light before the light impinges on the internal coupling optical elements 3012, 3014, 3016, and 3018.

[0079] In some embodiments, if the light source (e.g., LED or OLED) is pixelated and capable of outputting light with desired light characteristics (e.g., desired wavelength and / or polarization), the information stream may be formed to have both the desired light characteristics and encoded xy pixel information when emitted from the light source. In some other embodiments, the light with the desired light characteristics passes through a light modulation device, in which the xy pixel information is encoded. FIG. 8E illustrates the display system of FIG. 8B, showing a light modulation device 3070 for providing the xy pixel information to the image information stream. In some embodiments, the light modulation device 3070 may be part of the image input device 3021 and may be configured to provide the image information using a scanning fiber or one or more constant aperture display devices for providing the image information to a waveguide. In some embodiments, the light modulation device 3070 modifies the light as it passes through the device (e.g., the intensity of the light may be modified by passing it through pixel elements having controllably variable light transmission). In some other embodiments, the light modulating devices may modify the light by selectively redirecting (e.g., reflecting) the light to propagate within the waveguide stack 3000. Examples of light modulating devices include transmissive liquid crystal displays and micromirror devices (such as "digital light processing" or "DLP" systems such as those available from Texas Instruments, Inc.).

[0080] (Part II. Liquid crystal polarization gratings with Pancharatnam-Berry Phase Effect (PBPE) structure) This section focuses on liquid crystals, polarizing gratings, and Pancharatnam-Berry Phase In some embodiments, methods and apparatus are provided for fabricating liquid crystal grating structures with high diffraction efficiency, low sensitivity to angle of incidence, and high wavelength sensitivity. Various methods described herein include depositing a layer of liquid crystal material using inkjet technology and aligning the liquid crystal material using an imprint template.

[0081] In some embodiments, the liquid crystals, polarization gratings, and Pancharatnam-Berry Phase Effect (PBPE) structures disclosed in this Part II may be utilized to form light redirecting elements for various waveguides of waveguide stack 178 (FIG. 6) or 3000 (FIGS. 8A-8E). For example, such liquid crystals, polarization gratings, and Pancharatnam-Berry Phase Effect (PBPE) structures may be advantageously applied to form various incoupling optical elements disclosed herein, including incoupling optical elements 3012, 3014, 3016, and / or 3018 (FIGS. 8A-8E).

[0082] Various imaging and optical signal processing systems can include liquid crystal devices to control / manipulate the optical wavefront, wavelength, polarization, phase, intensity, angle and / or other properties of light. Liquid crystals are partially ordered materials whose molecules are often shaped like rods or plates or some other shape that can be aligned along a certain direction. The direction in which the molecules of liquid crystal are oriented can be manipulated by the application of electromagnetic forces, which can be used to control / manipulate the properties of light incident on the liquid crystal material.

[0083] Methods for fabricating liquid crystal devices and certain resulting structures are described herein.

[0084] The following detailed description is directed to certain embodiments for purposes of describing the innovative aspects. However, the teachings herein can be applied in many different ways. As will become apparent from the following description, the innovative aspects may be implemented in any optical component or device configured to manipulate one or more properties of incident light.

[0085] As discussed more fully below, innovative aspects described herein include fabricating liquid crystal devices using jet deposition techniques. For example, in one embodiment of a method for manufacturing a liquid crystal device, a layer of liquid crystal material is deposited on a substrate using jet deposition techniques (e.g., inkjet techniques). Surface relief features (e.g., PBPE structures) can be imprinted into the jet-deposited layer of liquid crystal material using a template. The surface relief features may be configured (e.g., with a specific spacing and / or height) to achieve specific light redirecting properties. In some other embodiments, the imprinting can be repeated at different levels to produce successive layered cross sections that, in combination, can behave as volumetric features as they exist in "bulk" volumetric phase materials and devices. In various embodiments, these surface relief features (and successive layered cross sections) can be modeled as "Bragg" structures. In general, such structures can be used to produce binary relief features, where there are diffraction-generating material / air, resist / air, resin / air, or liquid crystal material / air interfaces, or diffraction-generating material / low-index resist, resist / low-index resist, resin / low-index resist, or liquid crystal material / low-index resist interfaces. In these cases, the grating can be modeled as a "Raman-Nath" structure rather than a Bragg structure. The molecules of the liquid crystal material are aligned through the process of imprinting due to the physical shape of the nanostructures and their electrostatic interaction with the liquid crystal (LC) material. Alignment of the liquid crystal layer using the imprint pattern is discussed in more detail below.

[0086] In various embodiments, a layer of material (e.g., polymer) to serve as the optical alignment layer may be deposited using jet deposition techniques (where a jet or stream of material is directed onto the substrate), for example via inkjet onto the substrate or pre-coated substrate. The optical alignment layer is patterned by nanoimprinting using a template incorporating the desired LC alignment pattern. In some embodiments, this pattern is a PBPE pattern, and the template with physical relief may be fabricated using interference and / or lithographic techniques. The template is lowered onto a soft polymer resin, and UV light is used to cure the resin to a fixed state. In some embodiments, capillary action causes the template to fill with polymer material before it is cured. The template is retracted, leaving the patterned, cured resin in place on the substrate. A second step, using a deposition process (e.g., jet or spin coating), applies a layer of LC (e.g., LC suspended in resin) on top of the optical alignment layer. The LC aligns to the photo-alignment layer pattern underneath it, and once this occurs, the resin is fixed in place using UV light, heat, or a combination of both. In some other embodiments, LC suspended in a solvent (e.g., resin) is deposited (e.g., dispersed using jet or spin coating), and a template containing a nanoimprinted pattern (e.g., a PBPE pattern) is lowered into contact with the LC material. The LC takes up the relief profile of the template (e.g., by capillary action into the openings in the template), and the LC material is fixed in place using a curing process (e.g., UV, heat, or a combination of both). The resulting structure may be used directly as a functional element, or in some cases, a low refractive index material can be deposited over the imprinted liquid crystal material to fill the interstitial areas between the surface features imprinted in the liquid crystal material.

[0087] The low refractive index material can be configured as a planarization layer by adjusting the viscoelastic and chemical properties of a liquid crystal-based resist (e.g., a resin comprising a liquid crystal polymer or liquid crystal) or by contacting the top surface of the low refractive index material with a planarizing imprint template (e.g., a template having a substantially planar surface). In some other embodiments, the low refractive index material can be planarized by a chemical and / or mechanical planarization process. The planarization process is preferably selected to form a planarized surface that is smooth and reduces optical artifacts that may be caused by rough surfaces. Additional layers, such as additional liquid crystal layers, can be deposited over the liquid crystal layer using jetting techniques. The PBPE structures in different layers of the liquid crystal can be configured to diffract, steer, and / or scatter, or combine, different wavelengths of light. For example, red wavelengths, green wavelengths, and blue wavelengths can be diffracted, scattered, or redirected along different directions by the PBPE structures in different liquid crystal layers.

[0088] The different liquid crystal layers are preferably formed using materials that provide sufficient structural stability and adhesion to allow the layers to be stacked over one another. In some embodiments, organic or inorganic imprint resist materials may be used, including polymerizable materials that form optically transparent cured structures. As an example, the liquid crystal layers may include acrylic liquid crystal formulations. Acrylic liquid crystal layers may provide adhesive properties that facilitate stacking layers on top of one another.

[0089] It should be understood that both the liquid crystal material and the low refractive index material may be flowable materials, as discussed herein. In some embodiments, these materials may undergo a process to passivate them after contacting with the imprint template and before removing the contact template. The passivation process may include a curing process, as discussed herein.

[0090] As another example, in another embodiment of a method for manufacturing a liquid crystal device, a layer of photoresist material (e.g., resin or polymer) is deposited on a substrate. The deposition may be accomplished by various deposition methods, including spin coating. More preferably, in some embodiments, the deposition is accomplished using jetting techniques (e.g., inkjet techniques). The photoresist is imprinted with an imprint template or mold having surface relief features (e.g., PBPE structures). A layer of liquid crystal material can be deposited on the imprinted layer of photoresist using jetting techniques. The imprinted photoresist layer can act as an alignment layer and align the molecules of the liquid crystal material as it is deposited. An additional layer, such as an additional liquid crystal layer or a layer without liquid crystal, can be deposited over the liquid crystal layer using jetting techniques. In various embodiments, a planarization layer can be deposited over the deposited liquid crystal layer.

[0091] In the embodiments discussed herein, different types of liquid crystal materials, such as, for example, doped liquid crystal, undoped liquid crystal, and other non-liquid crystal materials, can be deposited using inkjet technology. Inkjet technology can provide a deposited liquid crystal layer or planarization layer of a thin and controlled (e.g., uniform) thickness. Inkjet technology can also provide layers of different thicknesses, such as layers of liquid crystal or other layers with different thicknesses in different areas on a surface, accommodating different pattern heights and maintaining a constant residual layer thickness beneath the imprinted pattern. Inkjet technology can advantageously provide thin layers, e.g., thicknesses of about 10 nm to 1 micron, or about 10 nm to about 10 microns, reducing waste compared to other techniques such as spin coating. Inkjet technology can facilitate the deposition of different liquid crystal compositions on the same substrate. In addition, inkjet nanoimprinting can produce very thin residual layer thicknesses. In the illustrated embodiment, the uniform areas beneath the imprint pattern can correspond to the residual layer. PBPE and other diffractive structures can exhibit variable and sometimes enhanced performance with very thin or zero residual layer thicknesses. Inkjet nanoimprinting approaches can be used to simultaneously deposit different types of materials across a given substrate and can be used to simultaneously produce variable thickness materials in different areas on a single substrate. This can be beneficial for PBPE structures, especially when combined in a single substrate with more conventional diffractive structures that may require other materials and / or thicknesses of resist.

[0092] The liquid crystal layer deposited by the jet technique can be cured using UV curing, thermal methods, freezing, annealing, and other methods. The imprint template can include complex groove geometries (e.g., grooves with multiple steps, gratings with different orientations, etc.). The liquid crystal devices fabricated using the methods described herein can include liquid crystal layers with gratings with different orientations and different PBPE structures.

[0093] The manufacturing methods using inkjet technology described herein can also be configured to produce polarizers with increased transmission and / or waveplates with subwavelength features and / or metamaterials. These and other aspects are discussed in detail below.

[0094] FIG. 9A illustrates an embodiment of a method for fabricating a liquid crystal device, preferably using inkjet technology. In the embodiment of the method illustrated in FIG. 9A, a layer of liquid crystal material 2000b is deposited on a substrate 2000a, for example, using inkjet technology, as shown in panel (i). The liquid crystal material can include doped or undoped liquid crystal material. In various embodiments, the liquid crystal material can be a polymer stabilized nematic liquid crystal material. The substrate 2000a can include glass, plastic, sapphire, polymer, or any other substrate material. The layer of liquid crystal material 2000b can have a thickness of about 20 nanometers to 2 microns. In some embodiments, the layer of liquid crystal material 2000b can have a thickness of about 0.5 microns to about 10 microns.

[0095] The layer of liquid crystal material 2000b can be imprinted with an imprint pattern 2000c, which includes wavelength and subwavelength scale surface features, as shown in panel (ii). The surface features can include PBPE structures, which can directly manipulate the phase of incident light. Without any loss of generality, the PBPE structures can be considered as a type of polarization grating structure. In various embodiments, the imprint pattern 2000c can include an array of grooves, which include PBPE structures. The array of grooves can form a liquid crystal grating structure, which can have high diffraction efficiency and low sensitivity to the angle of incidence. The grooves can have a depth of about 20 nm to about 1 micron and a width of about 20 nm to about 1 micron. In some embodiments, the grooves can have a depth of about 100 nm to about 500 nm and a width of about 200 nm to about 5000 nm. In some embodiments, the grooves can have a depth of about 20 nm to about 500 nm and a width of about 10 nm to about 10 microns. The PBPE structure can include a subwavelength pattern that encodes the phase profile directly onto the local orientation of the optical axis. The PBPE structure can be disposed on the surface of the liquid crystal grating structure. The PBPE structure can have a feature size of about 20 nm to about 1 micron. In some embodiments, the PBPE structure can have a feature size of about 10 nm to about 200 nm. In some embodiments, the PBPE structure can have a feature size of about 10 nm to about 800 nm. In various embodiments, the underlayer PBPE structure can be used as a matching layer for the volume alignment of the LC. The volume component arises automatically in this case as the LC will naturally align itself with the matching layer. In another embodiment, it may be desirable to match multiple layers including PBPE matching and the LC layer differently to compositely change the diffractive properties of the system, e.g., multiplex multiple wavelengths working, with each sublayer working only on a select subset of wavelengths.

[0096] In various embodiments, the imprint pattern 2000c can include simple geometric patterns such as multiple grooves or more complex patterns such as a stacked geometry including multiple grooves and recesses, as shown in FIG. 9B. In various embodiments, the imprint pattern 2000c can include multiple imprint layers, each of which includes a different imprint pattern, as shown in FIG. 9C. In the imprint pattern shown in FIG. 9C, imprint layer 2000c-1, imprint layer 2000c-2, and imprint layer 2000c-3 include multiple grooves that gradually decrease the space between adjacent grooves. In various embodiments, the imprint pattern can include patterns such as chevrons, spirals, arcs, etc. The imprint pattern can be fabricated on a semiconductor material or other structure using methods such as electron beam lithography or other lithography methods.

[0097] Referring to FIG. 9A, a layer of liquid crystal material 2000b is aligned to the imprinted pattern. The spaces between adjacent grooves can be filled with material 2000d. In some embodiments, the filling material can comprise a transparent material having a lower refractive index than that of the liquid crystal material, as shown in panel (iii). Such configurations can be used, for example, in waveguide structures. In this way, a high refractive index difference can be obtained between the liquid crystal grating structure and its surroundings, such that the liquid crystal grating can have high diffraction efficiency. As mentioned above, PBPE LC gratings can be made with a material / air interface, a resist / air interface, a resin / air interface, or a liquid crystal material / air interface, with air being the low refractive index "material". However, in some cases, it may be desirable to place another layer of material on top of the previously patterned layer, possibly in close contact, in which case it may be desirable to distribute and flatten the low refractive index curable resin that provides the stackable layer as well as preserve the different refractive index between the PBPE structures. In various embodiments, the liquid crystal grating can be configured as a Bragg liquid crystal grating. In various embodiments, the layer of low index material 2000d can be configured as a planarization layer. In such embodiments, the layer of low index material 2000d can be configured to be planarized by another imprint pattern 2000e, as shown in panel (iv).

[0098] FIG. 9D illustrates another embodiment of a method for fabricating a liquid crystal device, preferably using inkjet technology. In the embodiment of the method illustrated in FIG. 9A, a layer of resist 2000f is deposited on a substrate 2000a using inkjet technology, as shown in panel (i). The resist can include materials such as organic and inorganic based imprint materials, resins, or polymers. For example, the resist can include materials disclosed in U.S. Pat. No. 8,076,386, which is incorporated herein by reference in its entirety. In some embodiments, the resist layer 9F can have a thickness of about 20 nm to about 1 micron. In some embodiments, the resist layer 9F can have a thickness of about 10 nm to about 5 microns. The resist layer 2000f can be imprinted with an imprint pattern 2000c including volume and / or surface features, as shown in panel (ii). A layer of liquid crystal material 2000b can be deposited by inkjet on the imprinted resist layer 2000f, as shown in panel (iii). The imprinted resist layer may serve to align the liquid crystal material as it is jet deposited onto the imprinted resist layer 2000f.

[0099] Liquid crystal devices fabricated using the methods described above can be cured using UV curing, heat curing, freezing, or other curing methods.

[0100] Another embodiment of the method for fabricating a liquid crystal device is a Jet and Flash method. TMThe method includes imprinting the desired alignment structures in a UV-curable resist using J-FIL Imprinting Lithography and dispersing a liquid crystal polymer formulation from an inkjet. The liquid crystal polymer can have a high solvent content, for example, to provide a sufficiently low viscosity to allow efficient release through the inkjet. In various embodiments, the liquid crystal polymer can be in an isotropic state as it is dispersed. In some embodiments, the liquid crystal polymer can be configured to align along the alignment structures in the resist by repelling the solvent. An additional liquid crystal polymer layer can be disposed on top of the deposited liquid crystal polymer layer according to the aforementioned method. The formulation and viscosity of the liquid crystal material in the solvent can also be adjusted to achieve a fast drying process for the dispersed liquid crystal material.

[0101] 9E-9H illustrate an embodiment of a liquid crystal grating fabricated using the above-mentioned method. FIG. 9E illustrates a single-layer liquid crystal grating including a PBPE structure with high diffraction efficiency, high wavelength sensitivity, and low sensitivity to incident angle. The liquid crystal grating illustrated in FIG. 9E can be manufactured using the process depicted in FIG. 9A. For example, a liquid crystal polymer LCP1 can be deposited on a substrate, and an imprint template can be used to imprint a pattern on the liquid crystal polymer LCP1 such that the molecules of the liquid crystal polymer LCP1 are self-aligned to the imprinted pattern. The pattern can include a metasurface (e.g., a PBPE structure). FIG. 9F illustrates a liquid crystal grating including a PBPE structure with high diffraction efficiency, high wavelength sensitivity, and low sensitivity to incident angle. In the embodiment illustrated in FIG. 9F, the liquid crystal grating can be manufactured using the process depicted in FIG. 9D. For example, an alignment layer comprising a polymer (e.g., resist or resin) can be deposited on a substrate, and an imprint template can be used to imprint a pattern on the polymer. A layer of liquid crystal material is deposited on the alignment layer such that the molecules of the liquid crystal layer are aligned to the imprinted pattern on the alignment layer. The pattern can be part of the metasurface (e.g., PBPE structure). In various embodiments, the PBPE structure of the first liquid crystal layer (LCP1) can serve as an alignment structure for the second liquid crystal layer (LCP2).

[0102] FIG. 9G illustrates a three-layer liquid crystal grating including a PBPE structure with high diffraction efficiency, high wavelength sensitivity, and low sensitivity to incident angle. A multi-layer liquid crystal grating can be fabricated using the process depicted in FIG. 9A or FIG. 9D. For example, using the process of FIG. 9D, the multi-layer liquid crystal grating illustrated in FIG. 9G can be fabricated by aligning the molecules of a first liquid crystal layer (LCP1) using a first alignment layer with a first imprint pattern deposited on a substrate, aligning the molecules of a second liquid crystal layer (LCP2) using a second alignment layer with a second imprint pattern deposited on the first alignment layer, and aligning the molecules of a third liquid crystal layer (LCP3) using a third alignment layer with a third imprint pattern deposited on the second alignment layer. In some embodiments, the process of FIG. 9A may be utilized to form one or more of the first, second, and third liquid crystal layers (LCP1, LCP2, and LCP3, respectively) having aligned liquid crystal molecules. In such an embodiment, LCP1, LCP2, and LCP3 may each be formed by imprinting a pattern into a liquid crystal layer deposited across a substrate. The imprinting may be accomplished using an imprint template having a pattern that causes the liquid crystal molecules to align with the pattern. The imprint template may then be removed and a filler material may be deposited into the gaps left by removal of the imprint template.

[0103] With continued reference to FIG. 9G, each of the first, second, and third imprint patterns can be a metasurface (e.g., a PBPE structure). The first, second, and third imprint patterns can be different such that each imprint pattern is configured to selectively diffract / redirect different wavelengths of light in the incident beam and couple each of the different wavelengths into one or more waveguides. In some embodiments, the different wavelengths of light in the incident beam can be coupled into one or more waveguides at the same angle. However, in some other embodiments, as discussed below, the different wavelengths of light in the incident beam can be coupled into one or more waveguides at different wavelengths. In some other embodiments, the PBPE structure of the first liquid crystal layer (LCP1) can serve as a matching structure for the second liquid layer (LCP2), which in turn can serve as a matching structure for the third liquid layer (LCP3). The embodiment illustrated in Figure 9G can include different PBPE structures such that different wavelengths of light within an incident beam of light are diffracted or redirected at different output angles so as to be spatially separated. In various embodiments, the incident beam of light can be monochromatic or polychromatic. Conversely, a multi-layer liquid crystal structure can be used to combine different wavelengths of light, as illustrated in Figure 9H.

[0104] FIG. 9I illustrates a cross-section of a resist layer imprinted with the imprint pattern illustrated in FIG. 9B.

[0105] As mentioned above, the liquid crystal layer can be formed using a variety of materials. For example, in some embodiments, an acrylic liquid crystal formulation can be placed over a polymer matching imprint structure using inkjet and imprint technology. The acrylic composition can facilitate stacking different liquid crystal layers on top of each other, which can adhere to each other without an adhesive layer, thereby making the process simpler. Different liquid crystal layers can be stacked to achieve a desired effect, for example a desired polarization, diffraction, steering, or dispersion effect.

[0106] The above method can be used to fabricate liquid crystal polarization gratings and patterned guide layers using linear submasters in conjunction with jet dispensing techniques (e.g., J-FIL). Different liquid crystal grating structures can be fabricated by combining structures with different shapes, orientations, and / or pitches. The process is described in more detail with reference to FIG. 9J, which illustrates a first imprint structure with separate dispersed droplets or segments oriented along a first direction and a second imprint structure with separate droplets or segments oriented along a second direction. The separate droplets or segments of the first and second imprint structures can be dispersed using inkjet techniques. The separate droplets or segments of the first and second imprint structures can be fused or unfused in different embodiments. The separate droplets or segments in the first and second imprint structures can be combined to produce imprint structures with separate droplets or segments having different orientations. Liquid crystal material can be placed on the combined imprint patterns to produce liquid crystal gratings with molecules aligned along different orientations. The different orientations of the separate segments together can produce more complex lattice patterns within the aggregate, for example similar to those of PBPE.

[0107] The inkjet and imprinting methods discussed herein can also be used to fabricate other optical elements such as waveguide plates, optical retarders, polarizers, etc. For example, polarizers that are more transparent than existing polarizers can be fabricated using the methods described herein. The method includes disposing a patterned transparent or substantially transparent material, such as a polymer imprint, and depositing a polarizer material, such as an iodine solution containing a dichroic dye. The method includes imprinting a pattern onto the transparent polymer. The pattern can be linear grooves, chevrons, spirals, arcs, or any other simple or complex pattern. For example, the pattern can be a periodic linear grating structure. The polarizer material can then be deposited onto the patterned transparent polymer using the jet techniques previously described (e.g., J-FIL, etc.), imprint planarization, or by spin coating. Figures 9K and 9L illustrate different polarizer configurations that can be fabricated using the methods previously described. Polarizers fabricated using the techniques described herein can be more transparent than existing polarizers. Such components may be useful in devices that utilize low extinction polarizers, such as waveguide stacks for head-mounted display eyepieces for augmented and virtual reality as described elsewhere herein.

[0108] Subwavelength scale grating structures can induce birefringence in materials. For example, a one-dimensional grating can act as an artificial negative uniaxial material, whose optical axis is parallel to the grating vector. Such birefringence can be referred to as form birefringence. Thus, a substrate including a subwavelength scale grating structure can function as a waveplate. The amount of retardation provided by a substrate including a subwavelength scale grating structure can depend on the dimensions (e.g., height, width, pitch, etc.) of the grating pattern as well as the material refractive index. For example, a material with a higher refractive index that includes a pattern of subwavelength scale features can provide more retardation than a material with a lower refractive index that includes a similar pattern of subwavelength scale features. For example, inkjet and imprint techniques such as J-FIL enable high throughput Ultra Violet Nano-Imprint Lithography (UV-NIL) patterning capabilities over any defined area with very little material waste. For example, inkjet and imprint techniques such as J-FIL can also facilitate repeated stacking of imprinted layers. Imprint layers (single or multiple layers) with such subwavelength scale grating structures, with or without variations in geometry / orientation, can provide various degrees of phase shifting.Patterned birefringent material embodiments can enhance thin film integration capabilities in various optical applications.

[0109] The polarization of light output from a substrate including subwavelength scale grating structures may depend on the orientation, shape, and / or pitch of the subwavelength scale grating structures. Waveplate embodiments including subwavelength scale grating structures can also be fabricated using the inkjet and imprint methods described herein. FIG. 9M illustrates an embodiment of a waveguide plate 2005 having a light entrance surface 2006 and a light exit surface 2007. The waveguide plate 2005 can include multiple subwavelength scale grating features with various shapes, orientations, and / or pitches such that incident unpolarized light is output as polarized light. In various embodiments, the waveplate 2005 can include multiple stacks of thin transparent films 2009a, 2009b, and 2009c imprinted with subwavelength scale grating features with various shapes, orientations, and / or pitches. The grating features can be imprinted onto the transparent films using an imprint template, as shown in FIG. 9C. In various embodiments, the transparent films 2009a, 2009b, and 2009c can comprise an imprintable resist having a refractive index of about 1.45 to 1.75. The polarization of the light output from the multi-layer structure can depend on the shape, orientation, and / or pitch of the grating structure and the refractive index difference between the different layers. For the embodiment illustrated in FIG. 9M, the incident unpolarized light is converted to right-handed circularly polarized light by the waveguide plate 2005. In other embodiments, the waveguide plate can be configured to provide linearly polarized light, left-handed circularly polarized light, or light with any other polarization characteristics.

[0110] It is contemplated that the innovative aspects may be implemented in or associated with a variety of applications, such as imaging systems and devices, display systems and devices, spatial light modulators, liquid crystal-based devices, polarizers, waveguide plates, and the like. The structures, devices, and methods described herein may find use in displays, such as wearable displays (e.g., head-mounted displays), that may be used for augmented and / or virtual reality, among others. More generally, the described embodiments may be implemented in any device, apparatus, or system that may be configured to display images, whether moving (such as video) or stationary (such as still images), and whether text, graphics, or photographs. However, the described embodiments may be used in a variety of devices, including, but not limited to, mobile phones, multimedia Internet-enabled mobile phones, mobile television receivers, wireless devices, smartphones, Bluetooth devices, personal digital assistants (PDAs), wireless email receivers, handheld or portable computers, netbooks, notebooks, smartbooks, tablets, printers, copiers, scanners, fax devices, Global Positioning System (GPS) receivers / navigators, cameras, digital media players (such as MP3 players), camcorders, game consoles, watches, clocks, calculators, television monitors, flat panel displays, electronic reading devices, and the like. It is contemplated that the electronic devices may be contained within or associated with a variety of electronic devices, such as computers (e.g., electronic readers), computer monitors, automotive displays (including odometer and speedometer displays, etc.), cockpit controls and / or displays, camera view displays (such as a backup camera display in a vehicle), electronic photography, electronic bulletin boards or signs, projectors, building structures, microwave ovens, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washers, dryers, washer-dryers, parking meters, head mounted displays, and various imaging systems.Accordingly, the present teachings are not intended to be limited to only the embodiments depicted in the figures, but instead have wide applicability, as will be readily apparent to those skilled in the art.

[0111] Various modifications of the embodiments described in this disclosure may be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present disclosure. Thus, the claims are not intended to be limited to the embodiments shown herein, but should be accorded the widest scope consistent with the present disclosure, principles, and novel features disclosed herein. The word "exemplary" is used exclusively herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. In addition, those skilled in the art will readily appreciate that the terms "upper" and "lower," "above" and "below," and the like, are sometimes used to facilitate the description of the figures and indicate relative positions that correspond to the orientation of the figures on a properly oriented page, and may not reflect the proper orientation of the structures described herein in which those structures are implemented.

[0112] Certain features described herein in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in a combination and may even be initially claimed as such, one or more features from a claimed combination may in some cases be deleted from the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0113] Similarly, although operations are depicted in the figures in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown, or in a sequential order, or that all illustrated operations be performed, to achieve desired results. Additionally, the figures may depict more than one exemplary process diagrammatically in the form of a flow diagram. However, other operations not depicted may also be incorporated into the illustrative process that is generally illustrated. For example, one or more additional operations may be performed before, after, simultaneously with, or during any of the illustrated operations. In some circumstances, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the program components and systems described may generally be integrated together in a single software product or packaged into multiple software products. Additionally, other embodiments 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 desirable results.

[0114] Various exemplary embodiments of the present invention are described herein. Reference is made to these examples in a non-limiting sense. They are provided to illustrate the more broadly applicable aspects of the present invention. Various modifications may be made to the described invention, and equivalents may be substituted without departing from the true spirit and scope of the present invention. In addition, many modifications may be made to adapt a particular situation, material, composition, process, act or step of a process to the objective, spirit, or scope of the present invention. Moreover, as will be understood by those skilled in the art, each of the individual variations described and illustrated herein has distinct components and features that can be easily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. All such modifications are intended to be within the scope of the claims associated with this disclosure.

[0115] The present invention includes methods that may be performed using the device. The method may include the act of providing such a suitable device. Such provision may be performed by an end user. In other words, the act of "providing" simply requires the end user to obtain, access, access, locate, configure, activate, power on, or otherwise act to provide the required device in the method. The methods described herein may be carried out in any order of the described events that is logically possible, as well as the described order of events.

[0116] Exemplary aspects of the invention have been described above, along with details regarding material selection and manufacturing. As to other details of the invention, these can be understood in conjunction with the above-referenced patents and publications, and generally understood or understood by those skilled in the art. The same may be true with respect to method-based aspects of the invention in terms of additional acts as generally or theoretically adopted.

[0117] In addition, although the present invention has been described with reference to several embodiments that optionally incorporate various features, the present invention is not limited to those described or indicated as being considered with respect to each variation of the present invention. Various modifications may be made to the invention described, and equivalents may be substituted (whether described herein or not included for some brevity) without departing from the true spirit and scope of the invention. In addition, when a range of values ​​is provided, it is understood that all intervening values ​​between the upper and lower limits of that range, and any other stated or intervening values ​​within that stated range, are encompassed within the present invention.

[0118] It is also contemplated that any optional feature of the inventive variations described herein may be described and claimed independently or in combination with any one or more of the features described herein. Reference to a singular item includes the possibility that there are multiple identical items. More specifically, as used herein and in the claims associated therewith, the singular forms "a," "an," "said," and "the" include multiple referents unless specifically stated otherwise. In other words, the use of articles allows for "at least one" of the subject item in the above description as well as in the claims associated with this disclosure. Furthermore, it is noted that such claims may be drafted to exclude any optional element. Thus, this statement is intended to serve as a predicate for the use of such exclusive terms, such as "only," "only," and the like, in connection with the description of claim elements, or the use of "negative" limitations.

[0119] Without using such exclusive terms, the term "comprising" in the claims associated with this disclosure is intended to permit the inclusion of any additional elements, regardless of whether a given number of elements are recited in such claims or whether the addition of features can be considered as changing the nature of the elements recited in such claims. Except as specifically defined herein, all technical and scientific terms used herein are to be given their broadest possible commonly understood meanings while maintaining the validity of the claims.

[0120] The scope of the present invention is not intended to be limited to the examples provided and / or this specification, but rather is intended to be limited only by the scope of the claims associated with this disclosure.

Claims

1. 1. A display system comprising: an input device configured to output a multiplexed light stream including a first light stream having at least one first light characteristic and a second light stream having at least one second light characteristic different from the at least one first light characteristic; a waveguide comprising one or more incoupling optical elements arranged to receive the multiplexed light stream and selectively incoupling only the first light stream having the at least one first optical characteristic into the waveguide; the at least one first optical characteristic comprises one or more of a first polarization state and a first wavelength; The at least one second optical characteristic includes one or more of a second polarization state and a second wavelength, the second polarization state being different from the first polarization state and the second wavelength being different from the first wavelength; the one or more incoupling optical elements comprise one or more Pancharatnam-Berry Phase Effect (PBPE) structures, the display system further comprising a second waveguide, the second waveguide comprising one or more second incoupling optical elements arranged to receive at least a portion of the multiplexed light stream, the one or more second incoupling optical elements configured to selectively incoupling the second light stream having the at least one second optical characteristic into the second waveguide while being transparent to the first light stream having the at least one first optical characteristic, the one or more second incoupling optical elements comprising one or more second PBPE structures.

2. 2. The display system of claim 1, wherein the at least one first light characteristic comprises a first polarization state and the at least one second light characteristic comprises a second polarization state different from the first polarization state.

3. 10. The display system of claim 1, wherein the at least one first light characteristic comprises a first wavelength and the at least one second light characteristic comprises a second wavelength different from the first wavelength.

4. 2. The display system of claim 1, wherein the at least one first light characteristic includes a first polarization state and a first wavelength, and the at least one second light characteristic includes a second polarization state different from the first polarization state and a second wavelength different from the first wavelength.

5. The display system of claim 1 , wherein the second waveguide is configured to output light having a different level of wavefront curvature than the waveguide.

6. The display system of claim 1 , wherein the one or more incoupling optical elements and the one or more second incoupling optical elements at least partially overlap when viewed from an output end of the input device.

7. The display system of claim 1 , wherein the one or more incoupling optical elements are switchable between a transmissive state and an active light redirecting state.

8. The display system of claim 1 , wherein the one or more incoupling optical elements are formed on a surface of the waveguide.

9. The display system of claim 1 , wherein the one or more incoupling optical elements are formed within the waveguide.

10. The display system of claim 1 , wherein the input device is configured to simultaneously output both the first light stream and the second light stream toward the waveguide.

11. The display system of claim 1 , wherein the input device is configured to output the first and second light flows toward the waveguide at different times.

12. 10. The display system of claim 1, wherein the waveguide further comprises one or more out-coupling elements configured to output at least a portion of the in-coupled light propagating within the waveguide from the waveguide.

13. 10. The display system of claim 1, wherein the waveguide further comprises at least one of an exit pupil expander or an orthogonal pupil expander configured to increase a dimension of an eyebox.

14. The display system of claim 1 , wherein the input device comprises a scanning optical fiber.

15. The display system of claim 1 , wherein the input device comprises a light modulation device.

16. The display system of claim 1 , wherein the one or more incoupling optical elements comprise a liquid crystal material.

17. The display system of claim 1 , further comprising an eyepiece including the waveguide, the display system being a head-mountable display system.

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