Methods, devices, and systems for illuminating spatial light modulators

Abstract

To provide optical devices, including augmented reality imaging and visualization systems.SOLUTION: An optical device may include a wedge-shaped light turning element, including a first surface parallel to a horizontal axis and a second surface opposite to the first surface that is inclined with respect to the horizontal axis by a wedge angle. A light module including a number of light emitters can be configured to combine light from the emitters. A light input surface is between the first and second surfaces and receives light emitted from the emitters. An end reflector is disposed on a side opposite the light input surface. The second surface may be inclined such that a height of the light input surface is less than a height of the side opposite the light input surface. The light coupled into the light turning element may be reflected by the end reflector and / or reflected from the second surface towards the first surface.SELECTED DRAWING: None

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 62 / 474,591, filed March 21, 2017, and entitled "METHODS, DEVICES, AND SYSTEMS FOR ILLUMINATING SPATIAL LIGHT MODULATORS," which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to optical devices, including augmented reality imaging and visualization systems. [Background technology]

[0003] Modern computing and display technology has 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 input, while augmented reality or "AR" scenarios typically involve the presentation of digital or virtual image information as an augmentation to the user's visualization of the real world around them. Mixed reality or "MR" scenarios are a type of AR scenario that typically involve virtual objects integrated into and responsive to the natural world. For example, MR scenarios may include AR image content that appears blocked by or is perceived to otherwise interact with objects in the real world.

[0004] Referring to FIG. 1 , an augmented reality scene 10 is depicted. A user of the AR technology sees a real-world park-like setting 20 featuring people, trees, a building in the background, and a concrete platform 30. The user also perceives that they are "seeing" "virtual content," such as a robotic figure 40 standing on the real-world platform 30 and a flying, cartoon-like avatar character 50 that appears to be an anthropomorphic bumblebee. These elements 50, 40 are "virtual" in that they do not exist in the real world. The human visual perception system is complex, making it difficult to produce 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 AR or VR technology.

[0006] Polarizing beam splitters may be used in display systems to direct polarized light to a light modulator, which then directs this light to a viewer. Generally, there is a continuing demand to reduce the size of display systems, and consequently, there is also a demand to reduce the size of display system components, including components that utilize polarizing beam splitters. Summary of the Invention [Means for solving the problem]

[0007] Various implementations described herein include an illumination system configured to provide illumination (e.g., front light or back light) to one or more spatial light modulators (e.g., liquid crystal on silicon (LCOS) devices). The illumination systems discussed herein are configured to direct light having a first polarization state toward the spatial light modulators and direct light reflected from the spatial light modulators having a second polarization state different from the first polarization toward a viewer. The illumination systems discussed herein can be configured to split a polarized light beam into components having reduced sizes.

[0008] The head-mounted display system can be configured to project light into a user's eye and display augmented reality image content within the user's field of view. The head-mounted display system may include a frame configured to be supported on the user's head. The head-mounted display system may also include an eyepiece disposed on the frame. At least a portion of the eyepiece may be transparent and / or positioned in front of the user's eye when the user wears the head-mounted display such that the transparent portion transmits light from the environment in front of the user to the user's eye to provide a view of the environment in front of the user. The eyepiece may include one or more waveguides positioned to direct light into the user's eye.

[0009] The head-mounted display system may further include a light source and / or a wedge-shaped light redirecting element configured to emit light. The wedge-shaped light redirecting element may include a first surface parallel to the axis. The wedge-shaped light redirecting element may further include a second surface disposed opposite the first surface and / or tilted with respect to the axis by a wedge angle α. A light input surface between the first and second surfaces may be configured to receive light emitted from the light source. The wedge-shaped light redirecting element may include an end reflector disposed on a side opposite the light input surface. The second surface of the wedge-shaped light redirecting element may be tilted such that the height of the light input surface is less than the height of the light input surface opposite the end reflector and / or such that light coupled into the wedge-shaped light redirecting element is reflected by the end reflector and redirected by the second surface towards the first surface.

[0010] The head mounted display system may further include a spatial light modulator positioned relative to the wedge-shaped light redirecting element to receive and modulate light emitted from the wedge-shaped light redirecting element. The wedge-shaped light redirecting element and the spatial light modulator may be positioned relative to the eyepiece to direct the modulated light into one or more waveguides of the eyepiece such that the modulated light is directed into the user's eye and forms an image therein.

[0011] The optical device may include a wedge-shaped light redirecting element. The optical device may include a first surface parallel to a horizontal axis and a second surface opposite the first surface that is tilted with respect to the horizontal axis by a wedge angle α. The optical device may include an optical module including multiple light emitters. The optical module may be configured to combine light for the multiple emitters. The optical device may further include a light input surface disposed relative to the optical module between the first and second surfaces and receiving light emitted from the multiple emitters. The optical device may include an edge reflector disposed on a side opposite the light input surface. The second surface may be tilted such that the height of the light input surface is less than the height of the side opposite the light input surface. Light coupled into the wedge-shaped light redirecting element may be reflected by the edge reflector and / or reflected from the second surface toward the first surface.

[0012] The illumination system may include a light source configured to emit light and a polarization-sensitive light redirecting element. The polarization-sensitive light redirecting element may include a first surface positioned parallel to the axis and a second surface opposite the first surface. The polarization-sensitive light redirecting element may include a light input surface between the first and second surfaces and configured to receive light emitted from the light source. The polarization-sensitive light redirecting element may further include an end reflector positioned on a side opposite the light input surface. The second surface of the polarization-sensitive light redirecting element may be such that light coupled into the polarization-sensitive light redirecting element is reflected by the end reflector and / or redirected by the second surface towards the first surface. The illumination system may further include a spatial light modulator positioned relative to the polarization-sensitive light redirecting element to receive and modulate light emitted from the polarization-sensitive light redirecting element. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 illustrates a user's view of an augmented reality (AR) device, according to some embodiments.

[0014] [Figure 2] FIG. 2 illustrates an example of a wearable display system, according to some embodiments.

[0015] [Figure 3] FIG. 3 illustrates a display system for simulating a three-dimensional image for a user, according to some embodiments.

[0016] [Figure 4] FIG. 4 illustrates aspects of an approach for simulating a three-dimensional image using multiple depth planes, according to some embodiments.

[0017] [Figure 5]5A-5C illustrate the relationship between the radius of curvature and the focal radius, according to some embodiments.

[0018] [Figure 6] FIG. 6 illustrates an example of a waveguide stack for outputting image information to a user, according to some embodiments.

[0019] [Figure 7] FIG. 7 illustrates an example of an output beam output by a waveguide, according to some embodiments.

[0020] [Figure 8] FIG. 8 illustrates an example of a stacked waveguide assembly, according to some embodiments, where each depth plane includes an image formed using multiple different primary colors.

[0021] [Figure 9A] FIG. 9A illustrates a cross-sectional side view of an example of a set of stacked waveguides, each including an internal coupling optical element, according to some embodiments.

[0022] [Figure 9B] FIG. 9B illustrates a perspective view of an example of multiple stacked waveguides of FIG. 9A, according to some embodiments.

[0023] [Figure 9C] FIG. 9C illustrates a top-down plan view of the multiple stacked waveguide example of FIGS. 9A and 9B, according to some embodiments.

[0024] [Figure 10] FIG. 10 diagrammatically illustrates an exemplary wedge illumination system, according to some embodiments.

[0025] [Figure 11] FIG. 11 illustrates a ray trace associated with the illumination system illustrated in FIG. 10, according to some embodiments.

[0026] [Figure 12A] FIG. 12A illustrates a perspective view of the lighting system illustrated in FIG. 10, according to some embodiments.

[0027] [Figure 12B] FIG. 12B illustrates an exploded perspective view of the lighting system illustrated in FIG. 12A, according to some embodiments.

[0028] [Figure 13A] FIG. 13A illustrates a method of fabricating a polarization sensitive reflector according to some embodiments.

[0029] [Figure 13B] FIG. 13B illustrates a polarization sensitive reflector according to some embodiments.

[0030] [Figure 13C] FIG. 13C illustrates a method of fabricating a polarization-sensitive reflector fabricated as shown in FIG. 13A, according to some embodiments.

[0031] [Figure 13D] FIG. 13D illustrates a polarization-sensitive reflector fabricated using the method illustrated in FIGS. 13A-13C, according to some embodiments.

[0032] [Figure 14A] FIG. 14A illustrates a polarizing coating with a cholesteric liquid crystal grating, according to some embodiments.

[0033] [Figure 14B] FIG. 14B illustrates a polarizing coating with a cholesteric liquid crystal grating, according to some embodiments.

[0034] [Figure 15] FIG. 15 illustrates coating locations for a polarizing beam splitter, according to some embodiments.

[0035] [Figure 16] FIG. 16 illustrates features of a polarizing beam splitter, according to some embodiments.

[0036] [Figure 17-1] 17A-17H illustrate various exemplary configurations of illumination modules in conjunction with polarizing beam splitters, according to some embodiments. [Figure 17-2] 17A-17H illustrate various exemplary configurations of illumination modules in conjunction with polarizing beam splitters, according to some embodiments.

[0037] [Figure 18-1] 18A-18M illustrate various exemplary configurations of lighting modules, according to some embodiments. [Figure 18-2] 18A-18M illustrate various exemplary configurations of lighting modules, according to some embodiments.

[0038] [Figure 18-3] 18N-18P illustrate various exemplary configurations of illumination modules combined with polarizing beam splitters, according to some embodiments.

[0039] [Figure 18-4] 18Q-18V illustrate various exemplary configurations of lighting modules, according to some embodiments.

[0040] [Figure 19] FIG. 19 illustrates an illumination system that may include a delivery system between the illumination module and the PBS, according to some embodiments.

[0041] [Figure 20A] FIG. 20A shows an exemplary light pipe integrator including a color source area according to some embodiments.

[0042] [Figure 20B] FIG. 20B shows an exemplary light pipe integrator including a color source area according to some embodiments.

[0043] [Figure 20C] 20C-20D show an alternative lighting module embodiment. [Figure 20D] 20C-20D show an alternative lighting module embodiment.

[0044] [Figure 21A] FIG. 21A shows the basic structure of an integrated dichroic combiner and optical integrator according to some embodiments.

[0045] [Figure 21B] FIG. 21B shows an example of the embodiment of FIG. 21A with a light emitter and a combining element, according to some embodiments.

[0046] [Figure 21C] FIG. 21C shows an example of the embodiment of FIG. 21A with only one combining element and optical integrator, according to some embodiments.

[0047] [Figure 22A] FIG. 22A shows a side view of an exemplary reflective lighting module, according to some embodiments.

[0048] [Figure 22B] FIG. 22B shows an isometric view of the exemplary reflective lighting module of FIG. 22A, according to some embodiments.

[0049] [Figure 22C] FIG. 22C shows an exemplary reflective lighting module including an extension, according to some embodiments.

[0050] [Figure 23A] FIG. 23A shows an example of a broadband light source, according to some embodiments.

[0051] [Figure 23B] FIG. 23B shows the off state of a first color cell according to some embodiments.

[0052] [Figure 23C] FIG. 23C shows the off state of a second color cell according to some embodiments.

[0053] [Figure 23D] FIG. 23D shows the off state of a third color cell according to some embodiments.

[0054] [Figure 23E] FIG. 23E shows an on state, which provides transmission of each color of light, according to some embodiments.

[0055] [Figure 24] FIG. 24 illustrates a perspective view of a lighting system, according to some embodiments.

[0056] [Figure 25] FIG. 25 illustrates a perspective view of another example lighting system, according to some embodiments.

[0057] [Figure 26] FIG. 26 schematically illustrates an illumination system configured to provide illumination to a spatial light modulator, according to some embodiments.

[0058] [Figure 27] 27 schematically illustrates an illumination system configured to provide illumination to a spatial light modulator associated with various embodiments of the display system discussed herein, according to some embodiments. The inset in FIG. 27 provides a close-up view of a section of the illumination system showing redirection features including microstructures that reflect collimated light, according to some embodiments.

[0059] [Figure 28A] FIG. 28A illustrates an example implementation of a turning feature included within the lighting system illustrated in FIG. 27, according to some embodiments.

[0060] [Figure 28B] FIG. 28B illustrates an example implementation of a turning feature included within the lighting system illustrated in FIG. 27, according to some embodiments.

[0061] [Figure 28C] FIG. 28C illustrates an example implementation of a turning feature included within the lighting system illustrated in FIG. 27, according to some embodiments.

[0062] [Figure 28D] FIG. 28D illustrates an example implementation of a turning feature included within the lighting system illustrated in FIG. 27, according to some embodiments.

[0063] [Figure 29A] FIG. 29A illustrates an example implementation of an illumination system including turning features with refractive power, according to some embodiments.

[0064] [Figure 29B] FIG. 29B illustrates an example implementation of an illumination system including turning features with optical power, according to some embodiments.

[0065] [Figure 30] FIG. 30 illustrates an embodiment of an illumination system including a reflective holographic component, according to some embodiments.

[0066] [Figure 31] FIG. 31 schematically illustrates a method of manufacturing an embodiment of a compact polarizing beam splitter as discussed herein, according to some embodiments.

[0067] [Figure 32] FIG. 32 illustrates an example of a display device incorporating a light recycling system for recycling light, according to some embodiments.

[0068] [Figure 33] FIG. 33 illustrates an example of a display device that incorporates a light recycling system for recycling light, according to some embodiments.

[0069] [Figure 34] FIG. 34 illustrates an example of a display device that incorporates a light recycling system for recycling light, according to some embodiments.

[0070] [Figure 35] FIG. 35 illustrates an example of a display device that incorporates a light recycling system for recycling light, according to some embodiments.

[0071] [Figure 36] FIG. 36 illustrates an example of a display device that incorporates a light recycling system for recycling light, according to some embodiments.

[0072] [Figure 37] FIG. 37 illustrates a lighting device with an internal coupling element that deflects light to couple into a light redirecting element, according to some embodiments.

[0073] [Figure 38] FIG. 38 illustrates an illumination module and polarizing beam splitter used in combination with an eyepiece to provide an image thereto, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0074] The drawings are provided to illustrate example embodiments and are not intended to limit the scope of the present disclosure. Like reference numbers refer to like parts throughout.

[0075] Display systems may employ spatial light modulators that modulate the polarization state of light. Such spatial light modulators may include, for example, liquid crystal spatial light modulators, such as liquid crystal on silicon (LCOS). Such spatial light modulators may include an array of individually activated pixels that may or may not rotate a polarization state, such as a linear polarization state, depending on the state of the pixel. For example, such a spatial light modulator may be illuminated with light having a first orientation of linear polarization (e.g., s-polarized light). Depending on the state of the pixel (e.g., on or off), the spatial light modulator may or may not selectively rotate light incident on that pixel with a first orientation of linear polarization (s-polarized light) to produce a second orientation of linear polarization (e.g., p-polarized light). A polarizer or analyzer may be used to filter out light from one of the polarization states, thereby converting the polarization modulation into intensity modulation that can form an image.

[0076] Because such spatial light modulators operate on linearly polarized light, some illumination devices are configured to direct linearly polarized light to the spatial light modulator. More specifically, in some such embodiments, the spatial light modulator may be configured to receive light having a certain polarization state (e.g., an s-polarization state).

[0077] Conventional illumination systems configured to provide illumination to spatial light modulators configured to modulate the polarization state of light can include thick and bulky polarizing beam splitters. It would be advantageous to reduce the size of the polarizing beam splitters in illumination systems that provide illumination to spatial light modulators. These and other concepts are discussed below.

[0078] Reference is now made to the drawings, wherein like reference numerals refer to like parts throughout.

[0079] FIG. 2 illustrates an example of a wearable display system 60. The display system 60 includes a display 70 and various mechanical and electronic modules and systems to support the functionality of the display 70. The display 70 may be coupled to a frame 80, which is wearable by a display system user or viewer 90 and configured to position the display 70 directly in front of the user's 90 eyes. The display 70 may be considered eyewear in some embodiments. In some embodiments, a speaker 100 is coupled to the frame 80 and configured to be positioned adjacent to the user's 90 ear canal (in some embodiments, another speaker, not shown, may optionally be positioned adjacent the user's other ear canal to provide stereo / shapeable sound control). The display system may also include one or more microphones 110 or other devices to detect sound. In some embodiments, the microphones are configured to allow a user to provide input or commands to the system 60 (e.g., voice menu command selections, natural language queries, etc.) and / or enable audio communication with other persons (e.g., other users of similar display systems). The microphone may further be configured as an ambient sensor to collect audio data (e.g., sounds from the user and / or the environment). In some embodiments, the display system may also include an ambient sensor 120a, which may be separate from the frame 80 and attached to the body of the user 90 (e.g., on the head, torso, limbs, etc. of the user 90). The ambient sensor 120a, in some embodiments, may be configured to obtain data characterizing a physiological state of the user 90. For example, the sensor 120a may be an electrode.

[0080] 2 , the display 70 is operably coupled to a local data processing module 140 by a communication link 130, such as wired or wireless connectivity, which may be mounted in a variety of configurations, such as fixedly attached to the frame 80, fixedly attached to a helmet or hat worn by the user, embedded within headphones, or otherwise removably attached to the user 90 (e.g., in a backpack-type configuration, a belt-type configuration). Similarly, the sensor 120 a may be operably coupled to the local data processing module 140 by a communication link 120 b, e.g., wired or wireless connectivity. The local processing and data module 140 may comprise a hardware processor and digital memory, such as non-volatile memory (e.g., flash memory or a hard disk drive), both of which may be utilized to aid in processing, caching, and storing data. The data includes a) captured data from sensors (such as image capture devices (cameras, etc.), microphones, inertial measurement units, accelerometers, compasses, GPS units, wireless devices, gyroscopes, and / or other sensors disclosed herein (which may be operatively coupled to frame 80 or otherwise attached to user 90, for example) and / or b) data obtained and / or processed using remote processing module 150 and / or remote data repository 160 (including data related to virtual content), possibly for passage to display 70 after processing or retrieval. Local processing and data module 140 may be operatively coupled to remote processing module 150 and remote data repository 160 by communication links 170, 180, such as via wired or wireless communication links, such that these remote modules 150, 160 are operatively coupled to each other and available as resources to local processing and data module 140. In some embodiments, the local processing and data module 140 may include one or more of an image capture device, a microphone, an inertial measurement unit, an accelerometer, a compass, a GPS unit, a wireless device, and / or a gyroscope.In some other embodiments, one or more of these sensors may be mounted on the frame 80 or may be freestanding structures that communicate with the local processing and data module 140 via wired or wireless communication paths.

[0081] 2 , in some embodiments, remote processing module 150 may comprise one or more processors configured to analyze and process data and / or image information. In some embodiments, remote data repository 160 may comprise a digital data storage facility that may be available through the Internet or other networking configuration in a “cloud” resource configuration. In some embodiments, remote data repository 160 may include one or more remote servers that provide information, for example, information for generating augmented reality content, to local processing and data module 140 and / or remote processing module 150. In some embodiments, all data is stored and all computations are performed within the local processing and data module, allowing for fully autonomous use from the remote module.

[0082] Referring now to FIG. 3, the perception of an image as “three-dimensional” or “3-D” can be achieved by providing a slightly different presentation of the image to each eye of a viewer. FIG. 3 illustrates a conventional display system for simulating a three-dimensional image for a user. Two distinct images 190, 200, one for each eye 210, 220, are output to the user. The images 190, 200 are spaced from the eyes 210, 220 by a distance 230 along the optical or z-axis parallel to the viewer's line of sight. The images 190, 200 are flat, and the eyes 210, 220 can focus on the images by assuming a single accommodative state. Such a 3-D display system relies on the human visual system to combine the images 190, 200 and provide the perception of depth and / or scale of the combined image.

[0083] However, it should be understood 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 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 two eyes relative to each other (e.g., eye rotation, in which the pupils move toward or away from each other to converge the gaze of the eyes and fixate on an object) is closely linked to the focusing (or “accommodation”) of the eye's lens and pupil. Under normal conditions, changing the focus of the eye's lens or accommodating the eye to change focus from one object at a different distance to another will automatically produce a matching change in convergence to the same distance, a relationship known as the "accommodation-vergence reflex" and pupil dilation or constriction. Similarly, changes in convergence will, under normal conditions, induce a matching change in accommodation in lens shape and pupil size. 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, among other things, simply provide different presentations of a scene, but are uncomfortable for many viewers because the eyes view all image information in a single, accommodated state, working against the "accommodation-vergence reflex." Display systems that offer better matching between accommodation and convergence may produce a more realistic and comfortable simulation of three-dimensional images.

[0084] FIG. 4 illustrates aspects of an approach for simulating a three-dimensional image using multiple depth planes. With reference to FIG. 4 , objects at various distances from the eyes 210, 220 on the z-axis are accommodated by the eyes 210, 220 so that the objects are in focus. The eyes 210, 220 assume a particular accommodated state and focus on objects at different distances along the z-axis. As a result, a particular accommodated state may be said to be associated with a particular one of the depth planes 240 having an associated focal length such that an object or portion of an object at a particular depth plane is in focus when the eye is in the accommodated state for that depth plane. In some embodiments, a three-dimensional image may be simulated by providing a different presentation of an image for each eye 210, 220 and by providing a different presentation of an image corresponding to each of the depth planes. While shown as separate for clarity of illustration, it should be understood that the fields of view of the eyes 210, 220 may overlap, for example, as the distance along the z-axis increases. Additionally, although shown as flat for ease of illustration, it should be understood that the contour of the depth plane may be curved in physical space so that all features within the depth plane are in focus with the eye in a particular accommodative state.

[0085] The distance between an object and the eye 210 or 220 can also change the amount of divergence of light from the object as viewed by that eye. Figures 5A-5C illustrate the relationship between distance and divergence of light rays. The distance between the object and the eye 210 is represented by decreasing distances R1, R2, and R3. As shown in Figures 5A-5C, 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 from the user's eye. The curvature increases as the distance between the object and the eye 210 decreases. As a result, the divergence of light rays at different depth planes also differs, and the divergence increases as the distance between the depth plane and the viewer's eye 210 decreases. While only a single eye 210 is illustrated in FIGS. 5A-5C and various other figures herein for clarity of illustration, it should be understood that the discussion regarding eye 210 may apply to both eyes 210 and 220 of a viewer.

[0086] Without being limited by theory, it is believed that the human eye is typically capable of interpreting a finite number of depth planes to provide depth perception. As a result, a highly realistic simulation of perceived depth can be achieved by providing the eye with different representations of images corresponding to each of these limited number of depth planes. The different representations may be focused separately by the viewer's eyes, thereby serving to provide depth cues to the user based on the ocular accommodation required to focus on different image features for a scene located on the different depth planes and / or based on the observation of different image features on the different depth planes that are out of focus.

[0087] FIG. 6 illustrates an example of a waveguide stack for outputting image information to a user. Display system 250 includes a stack of waveguides or stacked waveguide assembly 260 that can be utilized to provide a three-dimensional perception to the eye / brain using multiple waveguides 270, 280, 290, 300, 310. In some embodiments, display system 250 is system 60 of FIG. 2, and FIG. 6 schematically illustrates some portions of system 60 in greater detail. For example, waveguide assembly 260 may be part of display 70 of FIG. 2. It should be understood that display system 250 may be considered a light field display in some embodiments. Additionally, waveguide assembly 260 may also be referred to as an eyepiece.

[0088] Continuing with reference to FIG. 6, the waveguide assembly 260 may also include multiple features 320, 330, 340, 350 between the waveguides. In some embodiments, the features 320, 330, 340, 350 may be one or more lenses. The waveguides 270, 280, 290, 300, 310 and / or multiple lenses 320, 330, 340, 350 may be configured to transmit image information to the eye using various levels of wavefront curvature or ray divergence. Each waveguide level may be associated with a particular depth plane and configured to output image information corresponding to that depth plane. The image injection devices 360, 370, 380, 390, 400 may act as light sources for the waveguides and may be utilized to inject image information into the waveguides 270, 280, 290, 300, 310, each configured to disperse incident light across each individual waveguide for output toward the eye 210, as described herein. Light exits output surfaces 410, 420, 430, 440, 450 of the image injection devices 360, 370, 380, 390, 400 and is injected into corresponding input surfaces 460, 470, 480, 490, 500 of the waveguides 270, 280, 290, 300, 310. In some embodiments, each input surface 460, 470, 480, 490, 500 may be an edge of the corresponding waveguide or may be a portion of a major surface of the corresponding waveguide (i.e., one of the waveguide surfaces that directly faces the world 510 or the viewer's eye 210). In some embodiments, a single beam of light (e.g., a collimated beam) may be launched into each waveguide, outputting a total field of cloned collimated beams that are directed toward the eye 210 at a particular angle (and divergence) corresponding to the depth plane associated with the particular waveguide. In some embodiments, a single one of the image launch devices 360, 370, 380, 390, 400 may be associated with and launch light into multiple (e.g., three) waveguides 270, 280, 290, 300, 310.

[0089] In some embodiments, each of the image input devices 360, 370, 380, 390, 400 is a discrete display that generates image information for input into a corresponding waveguide 270, 280, 290, 300, 310. In some other embodiments, the image input devices 360, 370, 380, 390, 400 are the output of a single multiplexed display that may, for example, send image information via one or more optical conduits (such as fiber optic cables) to each of the image input devices 360, 370, 380, 390, 400. It should be understood that the image information provided by the image input devices 360, 370, 380, 390, 400 may include light of different wavelengths or colors (e.g., different primary colors, as discussed herein).

[0090] In some embodiments, light injected into the waveguides 270, 280, 290, 300, 310 is provided by a light projector system 520, which includes a light module 540, which may include a light emitter such as a light emitting diode (LED). Light from the light module 540 may be directed and modified by a light modulator 530, e.g., a spatial light modulator, via a beam splitter 550. The light modulator 530 may be configured to vary the perceived intensity of the light injected into the waveguides 270, 280, 290, 300, 310. Examples of spatial light modulators include liquid crystal displays (LCDs), including liquid crystal on silicon (LCOS) displays. It should be understood that image input devices 360, 370, 380, 390, 400 are illustrated diagrammatically and in some embodiments these image input devices may represent different light paths and locations within a common projection system configured to output light into associated ones of waveguides 270, 280, 290, 300, 310.

[0091] In some embodiments, the display system 250 may be a scanning fiber display comprising one or more scanning fibers configured to project light in various patterns (e.g., raster scan, spiral scan, Lissajous pattern, etc.) into one or more waveguides 270, 280, 290, 300, 310 and ultimately to the viewer's eye 210. In some embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 may diagrammatically represent a single scanning fiber or a bundle of scanning fibers configured to inject light into one or more waveguides 270, 280, 290, 300, 310. In some other embodiments, the illustrated image injection devices 360, 370, 380, 390, 400 may diagrammatically represent multiple scanning fibers or multiple bundles of scanning fibers, each configured to inject light into an associated one of the waveguides 270, 280, 290, 300, 310. It should be understood that one or more optical fibers may be configured to transmit light from the optical module 540 to one or more waveguides 270, 280, 290, 300, 310. It should be understood that one or more intervening optical structures may be provided between the scanning fiber or fibers and one or more waveguides 270, 280, 290, 300, 310, for example, to redirect light exiting the scanning fiber into one or more waveguides 270, 280, 290, 300, 310.

[0092] Controller 560 controls the operation of one or more of stacked waveguide assemblies 260, including the operation of image input devices 360, 370, 380, 390, 400, light source 540, and light modulator 530. In some embodiments, controller 560 is part of local data processing module 140. Controller 560 contains programming (e.g., instructions in a non-transitory medium) that coordinates the timing and provisioning of image information to waveguides 270, 280, 290, 300, 310, for example, according to any of the various schemes disclosed herein. In some embodiments, the controller may be a single integrated device or a distributed system connected by wired or wireless communication channels. Controller 560 may, in some embodiments, be part of processing module 140 or 150 (FIG. 2).

[0093] Continuing with reference to FIG. 6 , the waveguides 270, 280, 290, 300, and 310 may be configured to propagate light within each individual waveguide by total internal reflection (TIR). The waveguides 270, 280, 290, 300, and 310 may each be planar or have another shape (e.g., curved) with major top and bottom surfaces and edges extending between the major top and bottom surfaces. In the illustrated configuration, the waveguides 270, 280, 290, 300, and 310 may each include outcoupling optical elements 570, 580, 590, 600, and 610 configured to extract light from the waveguide by redirecting light propagating within each individual waveguide out of the waveguide and outputting image information to the eye 210. The extracted light may also be referred to as outcoupling light, and the outcoupling optical elements may also be referred to as light extraction optical elements. The extracted beam of light may be output by the waveguide at a location where light propagating within the waveguide strikes the light-extraction optical element. The outcoupling optical element 570, 580, 590, 600, 610 may be a grating, for example, including diffractive optical features as discussed further herein. While shown disposed on the bottom major surface of the waveguides 270, 280, 290, 300, 310 for ease of explanation and clarity of the drawings, in some embodiments the outcoupling optical element 570, 580, 590, 600, 610 may be disposed on the top and / or bottom major surfaces and / or directly within the volume of the waveguides 270, 280, 290, 300, 310, as discussed further herein. In some embodiments, the outcoupling optical elements 570, 580, 590, 600, 610 may be formed within a layer of material that is attached to a transparent substrate and forms the waveguides 270, 280, 290, 300, 310. In some other embodiments, the waveguides 270, 280, 290, 300, 310 may be monolithic pieces of material, and the outcoupling optical elements 570, 580, 590, 600, 610 may be formed on a surface of and / or within that piece of material.

[0094] Continuing with reference to FIG. 6 , as discussed herein, each waveguide 270, 280, 290, 300, 310 is configured to output light and form an image corresponding to a particular depth plane. For example, the waveguide 270 closest to the eye may be configured to deliver collimated light (injected into such waveguide 270) to the eye 210. The collimated light may represent an optical infinity focal plane. The next upper waveguide 280 may be configured to send collimated light that passes through a first lens 350 (e.g., a negative lens) before reaching the eye 210. Such first lens 350 may be configured to generate a slight convex wavefront curvature so that the eye / brain interprets light emerging from the next upper waveguide 280 as emerging from a first focal plane closer inward from optical infinity toward the eye 210. Similarly, the third upper waveguide 290 passes its output light through both the first 350 and second 340 lenses before reaching the eye 210. The combined refractive power of the first 350 and second 340 lenses may be configured to produce another, increasing amount of wavefront curvature so that the eye / brain interprets the light emerging from the third waveguide 290 as originating from a second focal plane closer inward toward the person from optical infinity, where the light from the next upper waveguide 280 was.

[0095] The other waveguide layers 300, 310 and lenses 330, 320 are similarly configured, with the highest waveguide 310 in the stack sending its output through all of the lenses between it and the eye for a collective focal power representing the focal plane closest to the person. To compensate for the stack of lenses 320, 330, 340, 350 when viewing / interpreting light originating from the world 510 on the other side of the stacked waveguide assembly 260, a compensating lens layer 620 may be placed on top of the stack to compensate for the collective power of the lower lens stacks 320, 330, 340, 350. Such a configuration provides as many perceived focal planes as there are available waveguide / lens pairs. Both the waveguide outcoupling optical elements and the focusing sides of the lenses may be static (i.e., not dynamic or electro-active). In some alternative embodiments, one or both may be dynamic using electro-active features.

[0096] In some embodiments, two or more of the waveguides 270, 280, 290, 300, 310 may have the same associated depth plane. For example, multiple waveguides 270, 280, 290, 300, 310 may be configured to output images set at the same depth plane, or multiple subsets of waveguides 270, 280, 290, 300, 310 may be configured to output images set at the same depth planes, with one set per depth plane. This may provide the advantage of forming tiled images to provide an extended field of view at those depth planes.

[0097] Continuing with reference to FIG. 6 , the outcoupling optical elements 570, 580, 590, 600, 610 may be configured to redirect light from its respective waveguide and output the light with an appropriate amount of divergence or collimation for a particular depth plane associated with that waveguide. As a result, waveguides with different associated depth planes may have different configurations of outcoupling optical elements 570, 580, 590, 600, 610, which output light with different amounts of divergence depending on the associated depth plane. In some embodiments, the light-extraction optical elements 570, 580, 590, 600, 610 may be volume or surface features, which may be configured to output light at specific angles. For example, the light-extraction optical elements 570, 580, 590, 600, 610 may be volume holograms, surface holograms, and / or diffraction gratings. In some embodiments, features 320, 330, 340, 350 may not be lenses. Rather, they may simply be spacers (e.g., cladding layers and / or structures for forming air gaps).

[0098] In some embodiments, the outcoupling optical elements 570, 580, 590, 600, 610 are diffractive features or "diffractive optical elements" (also referred to herein as "DOEs") that form a diffraction pattern. Preferably, the DOEs have a sufficiently low diffraction efficiency so that only a portion of the light in the beam is deflected toward the eye 210 with each intersection point of the DOE, while the remainder continues traveling through the waveguide via TIR. The light carrying the image information is thus split into several related output beams that exit the waveguide at various locations, resulting in a fairly uniform pattern of output emission toward the eye 210 for this particular collimated beam bouncing within the waveguide.

[0099] 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 may 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 may be switched to a refractive index that does not match that of the host medium (in which case the pattern actively diffracts incident light).

[0100] In some embodiments, a camera assembly 630 (e.g., a digital camera, including visible and infrared light cameras) may be provided to capture images of the eye 210 and / or tissue surrounding the eye 210, for example, to detect user input and / or monitor the physiological state of the user. As used herein, a camera may be any image capture device. In some embodiments, the camera assembly 630 may include an image capture device and a light source that projects light (e.g., infrared light) onto the eye, which may then be reflected by the eye and detected by the image capture device. In some embodiments, the camera assembly 630 may be mounted on the frame 80 ( FIG. 2 ) and may be in electrical communication with processing modules 140 and / or 150, which may process image information from the camera assembly 630. In some embodiments, one camera assembly 630 may be utilized per eye, monitoring each eye separately.

[0101] 7, an example of an output beam output by a waveguide is shown. While one waveguide is illustrated, it should be understood that other waveguides in waveguide assembly 260 (FIG. 6) may function similarly, and that waveguide assembly 260 includes multiple waveguides. Light 640 is launched into waveguide 270 at input surface 460 of waveguide 270 and propagates within waveguide 270 by TIR. At the point where light 640 impinges on DOE 570, a portion of the light exits the waveguide as output beam 650. Output beam 650 is illustrated as being approximately parallel, but may be redirected to propagate to eye 210 at an angle (e.g., forming a diverging output beam), as discussed herein and depending on the depth plane associated with waveguide 270. It should be understood that a nearly collimated exit beam may refer to a waveguide with outcoupling optics that outcouples light to form an image that appears to be set at a depth plane at a large distance (e.g., optical infinity) from the eye 210. Other waveguides or other sets of outcoupling optics may output a more divergent exit beam pattern, which would require the eye 210 to accommodate to a closer distance and focus on the retina, and would be interpreted by the brain as light from a distance closer to the eye 210 than optical infinity.

[0102] In some embodiments, a full-color image may be formed at each depth plane by overlaying an image in each of the primary colors, for example, three or more primary colors. FIG. 8 illustrates an example of a stacked waveguide assembly, with each depth plane including an image formed using multiple different primary colors. The illustrated embodiment shows depth planes 240a-240f, but more or fewer depths are also contemplated. Each depth plane may have three or more primary color images associated with it, including a first image in a first color G, a second image in a second color R, and a third image in a third color B. Different depth planes are indicated in the diagram by different numbers for diopters (dpt) following the letters G, R, and B. By way of example only, the number following each of these letters indicates the diopter (1 / m), i.e., the inverse distance of the depth plane from the viewer, and each box in the diagram represents an individual primary color image. In some embodiments, the exact locations of the depth planes for different primary colors may be varied to account for differences in the eye's focusing of light of different wavelengths. For example, different primary color images for a given depth plane may be placed on depth planes corresponding to different distances from the user. Such an arrangement may increase visual acuity and user comfort and / or reduce chromatic aberrations.

[0103] In some embodiments, light for each primary color may be output by a single dedicated waveguide, such that each depth plane may have multiple waveguides associated with it. In such embodiments, each box in the diagram containing the letter G, R, or B may be understood to represent an individual waveguide, and three waveguides may be provided per depth plane, resulting in three primary color images per depth plane. While the waveguides associated with each depth plane are shown adjacent to each other in this drawing for ease of illustration, it should be understood that in a physical device, the waveguides may all be arranged in a stack with one waveguide per level. In some other embodiments, multiple primary colors may be output by the same waveguide, such that, for example, only a single waveguide may be provided per depth plane.

[0104] 8, in some embodiments, G is green, R is red, and B is blue. In some other embodiments, other colors associated with other wavelengths of light, including magenta and cyan, may be used in addition to or replace one or more of red, green, or blue.

[0105] It should be understood that references throughout this disclosure to a given color of light are understood to encompass light of one or more wavelengths within the range of wavelengths of light that are perceived by a viewer as that given color. For example, red light may include one or more wavelengths of light that are within the range of about 620-780 nm, green light may include one or more wavelengths of light that are within the range of about 492-577 nm, and blue light may include one or more wavelengths of light that are within the range of about 435-493 nm.

[0106] In some embodiments, light source 540 (FIG. 6) may be configured to emit light at one or more wavelengths outside the range of a viewer's visual perception, e.g., infrared and / or ultraviolet wavelengths. Additionally, the waveguide incoupling, outcoupling, and other light redirecting structures of display 250 may be configured to direct and emit this light from the display toward the user's eye 210, e.g., for imaging and / or user stimulation applications.

[0107] Referring now to FIG. 9A , in some embodiments, light impinging on a waveguide may need to be redirected to incoupling the light into the waveguide. An incoupling optical element may be used to redirect and incoupling the light into its corresponding waveguide. FIG. 9A illustrates a cross-sectional side view of an example of a plurality or set 660 of stacked waveguides, each including an incoupling optical element. The waveguides may each be configured to output light of one or more different wavelengths or one or more different wavelength ranges. Stack 660 may correspond to stack 260 ( FIG. 6 ), and the illustrated waveguides of stack 660 may correspond to a portion of multiple waveguides 270, 280, 290, 300, 310, although it should be understood that light from one or more of image injection devices 360, 370, 380, 390, 400 is injected into the waveguide from a location requiring the light to be redirected for incoupling.

[0108] The illustrated set 660 of stacked waveguides includes waveguides 670, 680, and 690. Each waveguide includes an associated internal coupling optical element (which may also be referred to as the light input area on the waveguide), for example, internal coupling optical element 700 is disposed on a major surface (e.g., the top major surface) of waveguide 670, internal coupling optical element 710 is disposed on a major surface (e.g., the top major surface) of waveguide 680, and internal coupling optical element 720 is disposed on a major surface (e.g., the top major surface) of waveguide 690. In some embodiments, one or more of internal coupling optical elements 700, 710, 720 may be disposed on the bottom major surface of an individual waveguide 670, 680, 690 (particularly, one or more internal coupling optical elements are reflective polarizing optical elements). As shown, the internal coupling optical elements 700, 710, 720 may be disposed on the upper major surface of the respective waveguide 670, 680, 690 (or on top of the next lower waveguide), and in particular, the internal coupling optical elements are transmissive turning optical elements. In some embodiments, the internal coupling optical elements 700, 710, 720 may be disposed within the body of the respective waveguide 670, 680, 690. In some embodiments, as discussed herein, the internal coupling optical elements 700, 710, 720 are wavelength selective, such that they selectively redirect one or more wavelengths of light while transmitting other wavelengths of light. While illustrated on one side or corner of the respective waveguide 670, 680, 690, it should be understood that the internal coupling optical elements 700, 710, 720 may be disposed within other areas of the respective waveguide 670, 680, 690 in some embodiments.

[0109] As shown, the in-coupling optical elements 700, 710, 720 may be laterally offset from one another. In some embodiments, each in-coupling optical element may be offset to receive light without that light passing through another in-coupling optical element. For example, each in-coupling optical element 700, 710, 720 may be configured to receive light from different image input devices 360, 370, 380, 390, and 400, as shown in FIG. 6 , and may be separated (e.g., laterally spaced) from the other in-coupling optical elements 700, 710, 720 so as to receive substantially no light from others of the in-coupling optical elements 700, 710, 720.

[0110] Each waveguide also includes an associated optically dispersive element, for example, optically dispersive element 730 is disposed on a major surface (e.g., the top major surface) of waveguide 670, optically dispersive element 740 is disposed on a major surface (e.g., the top major surface) of waveguide 680, and optically dispersive element 750 is disposed on a major surface (e.g., the top major surface) of waveguide 690. In some other embodiments, optically dispersive elements 730, 740, 750 may be disposed on the bottom major surfaces of associated waveguides 670, 680, 690, respectively. In some other embodiments, optically dispersive elements 730, 740, 750 may be disposed on both the top and bottom major surfaces of associated waveguides 670, 680, 690, respectively, or optically dispersive elements 730, 740, 750 may be disposed on different ones of the top and bottom major surfaces in different associated waveguides 670, 680, 690, respectively.

[0111] Waveguides 670, 680, 690 may be spaced apart and separated, for example, by gas, liquid, and / or solid layers of material. For example, as shown, layer 760a may separate waveguides 670 and 680, and layer 760b may separate waveguides 680 and 690. In some embodiments, layers 760a and 760b are formed from a low refractive index material (i.e., a material having a lower refractive index than the material forming the immediately adjacent ones of waveguides 670, 680, 690). Preferably, the refractive index of the material forming layers 760a, 760b is 0.05 or greater, or 0.10 or less, than the refractive index of the material forming waveguides 670, 680, 690. Advantageously, the lower refractive index layers 760a, 760b may function as cladding layers that promote total internal reflection (TIR) ​​of light through the waveguides 670, 680, 690 (e.g., TIR between the top and bottom major surfaces of each waveguide). In some embodiments, the layers 760a, 760b are formed from air. Although not shown, it should be understood that the top and bottom of the illustrated set of waveguides 660 may include immediate cladding layers.

[0112] Preferably, for ease of manufacturing and other considerations, the materials forming waveguides 670, 680, 690 are similar or the same, and the materials forming layers 760a, 760b are similar or the same. In some embodiments, the materials forming waveguides 670, 680, 690 may differ between one or more waveguides, and / or the materials forming layers 760a, 760b may differ while still maintaining the various refractive index relationships discussed above.

[0113] 9A, light rays 770, 780, 790 enter the set of waveguides 660. It should be understood that light rays 770, 780, 790 may be injected into the waveguides 670, 680, 690 by one or more image injection devices 360, 370, 380, 390, 400 (FIG. 6).

[0114] In some embodiments, light rays 770, 780, 790 have different properties, e.g., different wavelengths or different wavelength ranges, which may correspond to different colors. Each of the incoupling optical elements 700, 710, 720 deflects incident light such that the light propagates through a respective one of the waveguides 670, 680, 690 by TIR. In some embodiments, each of the incoupling optical elements 700, 710, 720 selectively deflects one or more particular wavelengths of light while transmitting other wavelengths to the underlying waveguide and associated incoupling optical element.

[0115] For example, in-coupling optical element 700 may be configured to selectively deflect light ray 770 having a first wavelength or wavelength range while transmitting light rays 780 and 790 having different second and third wavelengths or wavelength ranges, respectively. Transmitted light ray 780 impinges on and is deflected by in-coupling optical element 710, which is configured to selectively deflect light of the second wavelength or wavelength range. Light ray 790 is deflected by in-coupling optical element 720, which is configured to selectively deflect light of the third wavelength or wavelength range.

[0116] 9A , the deflected light rays 770, 780, 790 are deflected to propagate through the corresponding waveguides 670, 680, 690. That is, the in-coupling optical element 700, 710, 720 of each waveguide deflects the light into its corresponding waveguide 670, 680, 690, in-coupling the light into the corresponding waveguide. The light rays 770, 780, 790 are deflected at an angle that causes the light to propagate through the respective waveguides 670, 680, 690 by TIR. The light rays 770, 780, 790 propagate through the respective waveguides 670, 680, 690 by TIR until they impinge on the waveguide's corresponding optical dispersive element 730, 740, 750.

[0117] 9B, a perspective view of the multiple stacked waveguide embodiment of FIG. 9A is illustrated. As previously described, in-coupled light rays 770, 780, 790 are deflected by in-coupling optical elements 700, 710, 720, respectively, and then propagate by TIR within waveguides 670, 680, 690, respectively. Light rays 770, 780, 790 then impinge on optically dispersive elements 730, 740, 750, respectively. Optically dispersive elements 730, 740, 750 deflect light rays 770, 780, 790 to propagate toward out-coupling optical elements 800, 810, 820, respectively.

[0118] In some embodiments, the optically dispersive elements 730, 740, 750 are orthogonal pupil expanders (OPEs). In some embodiments, the OPEs deflect or disperse light into the out-coupling optical elements 800, 810, 820, and in some embodiments, may also increase the beam or spot size of this light as it propagates into the out-coupling optical elements. In some embodiments, the optically dispersive elements 730, 740, 750 may be omitted, and the in-coupling optical elements 700, 710, 720 may be configured to deflect light directly into the out-coupling optical elements 800, 810, 820. For example, with reference to FIG. 9A , the optically dispersive elements 730, 740, 750 may be replaced with the out-coupling optical elements 800, 810, 820, respectively. In some embodiments, the outcoupling optical elements 800, 810, 820 are exit pupils (EPs) or exit pupil expanders (EPEs) that direct light toward the viewer's eye 210 ( FIG. 7 ). It should be understood that an OPE may be configured to increase the size of the eyebox in at least one axis, and that the EPE may increase the eyebox in an axis that intersects the axis of the OPE, e.g., orthogonal to the axis of the OPE. For example, each OPE may be configured to redirect a portion of the light striking the OPE to an EPE of the same waveguide, while allowing the remaining portion of the light to continue propagating down the waveguide. Upon striking the OPE, again, another portion of the remaining light is redirected to the EPE, and the remainder of that portion continues to propagate further down the waveguide, etc. Similarly, upon striking the EPE, a portion of the impinging light is directed out of the waveguide toward the user, and the remaining portion of that light continues to propagate through the waveguide until it again strikes an EP, at which point another portion of the impinging light is directed out of the waveguide, etc. As a result, a single beam of internally coupled light may be "replicated" each time a portion of that light is redirected by an OPE or EPE, thereby forming a cloned beam field of light, as shown in Figure 6. In some embodiments, the OPE and / or EPE may be configured to modify the size of the beam of light.

[0119] 9A and 9B, in some embodiments, a waveguide set 660 includes, for each primary color, waveguides 670, 680, 690, in-coupling optical elements 700, 710, 720, optically dispersive elements (e.g., OPEs) 730, 740, 750, and out-coupling optical elements (e.g., EPs) 800, 810, 820. The waveguides 670, 680, 690 may be stacked with an air gap / cladding layer between each one. The in-coupling optical elements 700, 710, 720 redirect or deflect incident light into that waveguide (with different in-coupling optical elements receiving light of different wavelengths). The light then propagates at an angle that will result in TIR within the individual waveguides 670, 680, 690. In the example shown, light ray 770 (e.g., blue light) is deflected by the first in-coupling optical element 700 in the manner described above, then continues bouncing down the waveguide, interacting with the optically dispersive element (e.g., OPE) 730 and then the out-coupling optical element (e.g., EP) 800. Light rays 780 and 790 (e.g., green and red light, respectively) pass through the waveguide 670, with light ray 780 impinging on and being deflected by the in-coupling optical element 710. Light ray 780 will then, via TIR, bounce down the waveguide 680, to its optically dispersive element (e.g., OPE) 740 and then the out-coupling optical element (e.g., EP) 810. Finally, light ray 790 (e.g., red light) passes through the waveguide 690 and impinges on the optically in-coupling optical element 720 of the waveguide 690. The light in-coupling optical element 720 deflects the light ray 790 so that it propagates by TIR to a light dispersive element (e.g., OPE) 750 and then to an out-coupling optical element (e.g., EP) 820. The out-coupling optical element 820 then finally out-couples the light ray 790 to a viewer, who also receives the out-coupled light from the other waveguides 670, 680.

[0120] FIG. 9C illustrates a top-down plan view of an example of the multiple stacked waveguides of FIGS. 9A and 9B. As shown, waveguides 670, 680, 690 may be vertically aligned, along with each waveguide's associated optically dispersive elements 730, 740, 750 and associated out-coupling optical elements 800, 810, 820. However, as discussed herein, the in-coupling optical elements 700, 710, 720 are not vertically aligned. Rather, the in-coupling optical elements are preferably non-overlapping (e.g., laterally spaced apart, as seen in the top-down view). As discussed further herein, this non-overlapping spatial arrangement facilitates the injection of light from different sources into different waveguides on a one-to-one basis, thereby allowing a specific light source to be uniquely coupled to a specific waveguide. In some embodiments, arrays including non-overlapping, spatially separated in-coupling optical elements may be referred to as shifted-pupil systems, and the in-coupling optical elements in these arrays may correspond to sub-pupils. Illumination system for optical projection system

[0121] 10 schematically illustrates an illumination system 1000, according to some embodiments. The illumination system 1000 includes an illumination module 102, a polarizing beam splitter 104 (hereinafter referred to as "PBS 104"), and a spatial light modulator 106 (hereinafter referred to as "SLM 106").

[0122] The illumination module 102 provides light to the PBS 104. The illumination module 102 is described in further detail below in the section entitled "Illumination Module."

[0123] The PBS 104 is configured to direct light having a first polarization state (e.g., an s-polarization state) from the illumination module 102 toward the SLM 106 and transmit light modulated by the SLM 106 having a second polarization state (e.g., a p-polarization state) toward a viewer. Transmitting the light toward the viewer may include, for example, transmitting the light toward one or more waveguides (e.g., a waveguide stack). Additional details are disclosed herein, for example, with respect to FIG. 38 below. The first and second polarization states may be orthogonal polarization states. The SLM 106 may extend along a horizontal axis parallel to the x-axis, along a vertical axis parallel to the y-axis, and along an orthogonal z-axis (outside the page). The optical axis of the illumination module 102 may be aligned parallel to the x-axis, and light from the illumination module 102 may be emitted in a cone having a half angle of less than approximately 60 degrees relative to the optical axis of the illumination module 102. In some embodiments, angles outside this range are also possible.

[0124] The PBS 104 can be configured to be compact (e.g., lightweight, small volume, and / or spatial extent). In some embodiments, the PBS 104 can be configured to have a dimension (e.g., length, width, height, radius, or any combination thereof) of less than or equal to about 5 mm. In some embodiments, the PBS 104 can be configured to have a dimension (e.g., length, width, height, radius, or any combination thereof) of less than about 10 mm. In some embodiments, the PBS 104 can be configured to have a dimension (e.g., length, width, height, radius, or any combination thereof) of about 2.0 mm to about 6.0 mm, about 3.0 mm to about 5.0 mm, about 3.5 mm to about 4.5 mm, or any value within these ranges / subranges or any range formed using any of these values.

[0125] The PBS 104 includes a light redirecting optical element or waveguide 112 , a polarization sensitive reflector 116 , and a refractive optical element 118 .

[0126] The waveguide 112 may include an optically transparent material (e.g., plastic, glass, acrylic, etc.). The waveguide 112 includes a first surface 113A disposed over the SLM 106 and a second surface 113B opposite the first surface 113A, where the second surface 113B contacts the polarization-sensitive reflector 116. In the implementation illustrated in FIG. 10 , in which the illumination system 1000 is configured as a front-emitting illumination system, the waveguide 112 can be disposed at the bottom of the PBS 104 such that the first surface 113A forms the bottom surface of the PBS 104. The waveguide 112 further includes a light input surface 113C between the first surface 113A and the second surface 113B. The light input surface 113C is configured to receive light from the illumination module 102.

[0127] The waveguide 112 further includes an end reflector 114 disposed on the side opposite the light input surface 113C. The end reflector 114 is configured to reflect light coupled into the waveguide 112 through the light input surface 113C. A portion of the light coupled into the waveguide 112 through the light input surface 113C propagates directly to the end reflector 114 without being reflected from any other surface, such as the first surface 113A or the second surface 113B. This light is reflected by the end reflector 114 toward the second surface 113B. A portion of the light coupled into the waveguide 112 through the light input surface 113C reflects from the first surface 113A by a process of total internal reflection (TIR) ​​before being reflected by the end reflector 114 toward the second surface 113B.

[0128] The end reflector 114 is configured to reflect light incident from the illumination module 102, for example, such that the reflected light is redirected by the polarization-sensitive reflector 116 along a direction approximately parallel to the normal to the top surface of the SLM 106 (e.g., parallel to the y-axis). For example, the end reflector 114 and the polarization-sensitive reflector 116 can be configured to redirect light (e.g., a majority of the light) from the illumination module 102 toward the SLM 106 within a cone of approximately ±10 degrees relative to the normal to the surface of the SLM 106. The end reflector 114 can include a plastic or glass material that forms a portion of the waveguide 112 coated with a reflective material (e.g., a metal or a dielectric). The end reflector 114 may also include one or more dielectric layers, such as a multilayer interference coating. The end reflector 114 can be glued or molded to the side of the waveguide 112 opposite the light input surface 113C.

[0129] The end reflector 114 can be a curved mirror (e.g., a spherical or parabolic mirror). Thus, the end reflector 114 may have refractive power and may have a focal point. For example, the end reflector 114 may be tilted and / or the curvature of the end reflector 114 may be varied so that the reflected light converges toward a focal point (convergence point) or virtual focal point, for example, in region 1344 away from the light source 102, as depicted in Figures 29A and 29B. The light converges toward a location farther from the first surface (e.g., first surface 113A) and the spatial light modulator 106 than from the light source 102. In such an embodiment, a turning feature (e.g., turning feature 1314) may be configured to provide refractive power and redirect the light reflected from the end reflector 114 toward the spatial light modulator 106. The redirecting feature can be configured to have positive refractive power, as depicted in Figure 29B, or negative refractive power, as depicted in Figure 29A. The illumination module 102 can be positioned at the focal point of the end reflector 114 so that light from the illumination module 102 is reflected along a direction parallel to the surface of the SLM 106 (e.g., parallel to the x-axis), or so that light reflected from the end reflector 114 is substantially collimated, and / or so that light reflected from the polarization-sensitive reflector 116 and directed onto the SLM 106 is substantially collimated. In such an embodiment, light reflected from the end reflector 114 (e.g., a majority of the light) is redirected substantially normal to the surface of the SLM 106 (e.g., parallel to the y-axis).

[0130] The first surface 113A can be planar and generally parallel to the surface of the SLM 106, which can extend along an axis parallel to the x-axis. The second surface 113B can be tilted or slanted relative to the first surface 113A, a horizontal axis parallel to the x-axis, and / or the SLM 106, such that the waveguide 112 is wedge-shaped. The second surface 113B can be tilted or slanted toward the light input surface 113C. The tilt angle (or wedge angle) "α" of the second surface 113B relative to the horizontal axis parallel to the first surface 113A can have a value in the range of about 15 degrees to about 45 degrees. In some embodiments, the tilt angle "α" of the second surface 113B relative to the first surface 113A can be within the range of about 20 degrees to about 35 degrees, about 24 degrees to about 30 degrees, or any value within any sub-range within any of these ranges / ranges formed by any of these values. Other values ​​are also possible.

[0131] In implementations of the wedge-shaped waveguide 112, the distance between the first surface 113A and the second surface 113B near the light input surface 113C (also referred to as the height of the light input surface 113C) may be less than the distance between the first surface 113A and the second surface 113B farther away from the light input surface 113C or near the end reflector 114. In various embodiments, the area of ​​the light input surface 113C can be less than the area of ​​the end reflector 114. In some implementations, the tilt angle “α” and the height of the light input surface 113C can be configured, for example, to receive substantially all light output from the lighting module 102 and emitted within a light cone. For example, if the lighting module 102 includes an LED, the light from the LED is emitted within a light cone having a half angle of approximately 41 degrees relative to the optical axis of the LED (which may be aligned parallel to the x-axis). In such embodiments, the tilt angle “α” of the second surface 113B can be about 20 degrees to about 30 degrees relative to a horizontal axis parallel to the x-axis, or relative to the first surface 113A or SLM 106 or its front surface, so that substantially all light output from the lighting module 102, including the LED, is coupled into the waveguide 112. The tilt angle “α” of the second surface 113B and / or the height of the light input surface 113C can be reduced if the lighting module 102 is not very divergent. In some embodiments, the tilt angle “α” of the second surface 113B can be less than 20 degrees if the lighting module 102 is coupled to the light input surface 113C via an optical fiber, for example, as illustrated in FIG. 19 .

[0132] A polarization-sensitive reflector 116 is disposed over the second surface 113B of the waveguide 112. The polarization-sensitive reflector 116 redirects light reflected from the end reflector 114 toward the SLM 106. For example, the polarization-sensitive reflector 116 may redirect light having a first polarization state (e.g., an s-polarization state) and may pass or reflect light having a second polarization state (e.g., a p-polarization state). The polarization-sensitive reflector 116 also transmits light reflected from the SLM 106. For example, the polarization-sensitive reflector 116 may transmit light having a second polarization state (e.g., a p-polarization state) and may block or reflect light having the first polarization state (e.g., an s-polarization state).

[0133] In various embodiments, the polarization-sensitive reflector 116 may be, for example, a polarization-selective coating, one or more thin film coatings, a dielectric coating, or a wire grid. The polarization-sensitive reflector 116 is configured to redirect light having a specific polarization state toward the SLM 106. For example, light having a first polarization state (e.g., an s-polarized state) from the illumination module 102 reflected from the end reflector 114 can be redirected toward the SLM 106 by the polarization-sensitive reflector 116. Furthermore, the polarization-sensitive reflector 116 is configured to transmit light having a specific polarization state toward the eyepiece (not shown in FIG. 10 ). For example, light having a second polarization state (e.g., a p-polarized state) is transmitted. The modulated light from the SLM 106 includes light having the second polarization state (e.g., a p-polarized state). The modulated light from the SLM 106 is transmitted by the polarization-sensitive reflector 116. The refractive optical element 118 is disposed across the waveguide 112. The refractive optical element 118 comprises a transparent material, such as a dielectric material (e.g., glass and / or plastic). The refractive optical element 118 may compensate for refractive optical effects introduced by the waveguide 112. For example, without any material or element disposed across the waveguide 112, light propagating from the SLM 106 through the waveguide 112 may be refracted in response to exiting the tilted polarization-sensitive reflector 116 and / or the second surface 113B of the waveguide 112. The refractive optical element 118 may provide a refractive index match to counteract this refraction. The upper surface of the refractive optical element 118 may also be parallel to the first surface 113A of the waveguide 112, which further reduces refraction of light reflected from the SLM 106 passing through the waveguide 112 and the refractive optical element 118. In various implementations, refractive optical element 118, which comprises a transparent material, may have a similar refractive index to waveguide 112 to reduce refraction at second surface 113B of waveguide 112. One or both may comprise glass and / or plastic in some examples.

[0134] In some embodiments, refractive optical element 118 may be configured to transmit light having a second polarization state (e.g., a p-polarization state) and block light having a first polarization state (e.g., an s-polarization state). In this manner, refractive optical element 118 can remove unmodulated light that is unintentionally transmitted through waveguide 112.

[0135] In some embodiments, the illumination system 1000 includes a front polarizer between the illumination module 102 and the PBS 104. For light traveling from the illumination module 102 toward the PBS 104, the front polarizer transmits light having a first polarization state (e.g., an s-polarization state) and blocks or reflects light having a second polarization state (e.g., a p-polarization state). In some embodiments, the PBS 104 may be designed such that for light traveling from the PBS 104 toward the illumination module 102, the front polarizer transmits light having a second polarization state (e.g., a p-polarization state) and blocks or reflects light having the first polarization state (e.g., an s-polarization state).

[0136] In some embodiments, the illumination system 1000 includes a clean-up polarizer between the PBS 104 and the eyepiece (not shown in FIG. 10). The clean-up polarizer transmits light having a second polarization state (e.g., a p-polarization state) and blocks light having a first polarization state (e.g., an s-polarization state). In this manner, the clean-up polarizer can remove unmodulated light that is unintentionally transmitted toward the eyepiece (not shown in FIG. 10).

[0137] The PBS 104 can be positioned relative to the waveguides 270, 280, 290, 300, 310 and the internal coupling elements thereon, discussed below with reference to Figure 6, such that light from the illumination system 1000, and specifically from the PBS 104, can be internally coupled into the waveguides 270, 280, 290, 300, 310. After the light is reflected from the SLM 106, it can be directed to the internal coupling elements of one or more of the waveguides 270, 280, 290, 300, 310 of the eyepiece.

[0138] The SLM 106 applies spatial modulation to the signal to provide an image. In the on state, the SLM 106 modulates input light from a first polarization state (e.g., an s-polarization state) to a second polarization state (e.g., a p-polarization state) so that a bright state (e.g., a white pixel) is indicated. The second polarization state may be the first polarization state modulated (e.g., shifted or rotated) by 90°. In the on state, light having the second polarization state is transmitted by the polarization-sensitive reflector 116 and proceeds downstream to the eyepiece (not shown in FIG. 10). In the off state, the SLM 106 does not rotate the input light from the first polarization state, and therefore a dark state (e.g., a black pixel) is indicated. In the off state, light having the first polarization state is reflected by the polarization-sensitive reflector 116, reflected within the waveguide 112, and / or becomes input light to the SLM 106. In the intermediate state, SLM 106 modulates the input light from a first polarization state to an elliptical polarization state, where a portion of the light having an elliptical polarization state (e.g., an s-polarization state) is transmitted by polarization-sensitive reflector 116 and a portion of the light having an elliptical polarization state (e.g., a p-polarization state) is reflected by polarization-sensitive reflector 116.

[0139] 11 illustrates a ray trace associated with the illumination system illustrated in FIG. 10 , according to some embodiments. The illumination module 102 may be configured to output and direct emitted light 124 into the PBS 104, i.e., the waveguide 112, through the light input surface 113C. In some embodiments, the emitted light 124 may propagate through the waveguide 112 and directly impinge on the end reflector 114. In some embodiments, the emitted light 124 may be reflected by the first surface 113A and / or possibly the second surface 113B via TIR, and the reflected light 126 may impinge on the end reflector 114. The light impinging on the end reflector 114 may be reflected and / or collimated. The reflected, collimated light 128 may impinge on the second surface 113B. Second surface 113B may be configured to selectively reflect light (e.g., light in a first polarization state) and redirect the light toward SLM 106. The redirected light 130 may propagate toward SLM 106, which may be configured to selectively modulate and reflect the redirected light 130. In some embodiments, for example, as shown, SLM 106 includes a reflective spatial light modulator array, such as a reflective LCD SLM array.

[0140] The redirected light 130 reflected from the SLM 106 propagates through the PBS 104, the waveguide 112, and / or the refractive optical element 118 and may therefore be transmitted through the PBS 104. For example, the transmitted light 132 may be in a different polarization state than the redirected light 130. For example, the transmitted light 132 may be in a second polarization state (e.g., p-polarized). The conversion (e.g., rotation) of the polarization state from a first polarization state to a second polarization state may be achieved in several ways. For example, the SLM 106 may selectively alter (e.g., rotate) the polarization state of light reflected therefrom from a first polarization (e.g., s-polarized) to a second polarization (p-polarized) depending on whether individual pixels within the SLM are set to a state for modulating light (e.g., an "on" state). Other configurations are also possible. The transmitted light 132 may be in a polarization state (e.g., a p-polarization state) that would allow the light to be transmitted through the polarization-sensitive reflector 116 and / or the refractive optical element 118.

[0141] FIG. 12A illustrates a perspective view of the lighting system 1000 illustrated in FIG. 10 , according to some embodiments, and FIG. 12B illustrates an exploded perspective view of the lighting system 1000 illustrated in FIG. 12 , according to some embodiments. As shown, the lighting system 1000 may include one lighting module 102. In other embodiments, the lighting system 1000 may include more than one lighting module. Examples of lighting systems including more than one lighting module are illustrated in FIGS. 24 and 25 . FIGS. 24 and 25 are described in more detail below. coating

[0142] 13A-13C illustrate a method of fabricating a polarization-sensitive reflector (e.g., polarization-sensitive reflector 116) according to some embodiments. Additional and / or alternative features of the method may be disclosed with respect to FIG. 31 below. The method includes stacking layers 702A-702L of transparent material. The transparent material may be, for example, glass, plastic, or other optically transparent material. Different layers within the stack of layers 702A-702L, e.g., each layer (e.g., any one of layers 702A-702L), can be coated and / or patterned with a polarization-selective coating, e.g., multiple thin films. The patterned layer can include sections that include a polarization-selective coating and sections that lack a polarization-selective coating. Different layers of layers 702A-702L, e.g., each layer 702A-702L, can be bonded and / or glued to adjacent layers. For example, an adhesive coating may be provided between one or more layers 702A-702L of the stack.

[0143] The stack of layers 702A-702L of transmissive material can be sliced ​​to obtain the polarization-sensitive reflector 716 illustrated in FIG. 13B. The slices may traverse one or more layers of the stack of layers 702A-702L. In some embodiments, the stack of layers 702A-702L may be sliced ​​at a transverse angle to the surface of the stack. The transverse angle may be an acute angle, for example, 5° to 10° with respect to the normal of the layers 702A-702L. o ~65 o The polarization sensitive reflector 716 may be the polarization sensitive reflector 116 of Figure 10. In the embodiment illustrated in Figure 13B, the polarization sensitive reflector 716 is made from a sliced ​​stack of layers of transmissive material (e.g., layers 702A-702L).

[0144] 13C, a polarization sensitive reflector 716 is disposed over, molded into, and / or attached to the waveguide 112. For example, the polarization sensitive reflector 716 is disposed over, molded into, and / or attached to the second surface 113B of the waveguide 112. The reflective optical element 118 is disposed over, molded into, and / or attached to the polarization sensitive reflector 716.

[0145] 13D illustrates a polarization-sensitive reflector 716 fabricated using the method illustrated in FIGS. 13A-13C , according to some embodiments. The polarization-sensitive reflector 716 includes a first section 742 having a polarization-selective element separated from a second section 746 having a polarization-selective element by a third section 744 that does not have a polarization-selective element or is otherwise configured to reflect less light (e.g., has little or no polarization-selective coating). Multiple such sections 742, 744, 746 may be disposed along one or more of the surfaces of the polarization-sensitive reflector 716. Light reflected from an end reflector (e.g., end reflector 114) that is incident on the third section 744 without a polarization-sensitive element will pass through that portion of the polarization-sensitive reflector 716 until it is incident on a section having a polarization-selective element, such as a section similar to the first section 742 and the second section 746. Such an implementation can be advantageous in increasing the uniformity of illumination across a spatial light modulator (e.g., SLM 106). As shown, light 754 is reflected by a section of a layer that includes polarization-sensitive elements, while light 756 is first passed through a section that does not include polarization-sensitive elements (or has polarization-sensitive elements that reflect less light than other polarization-sensitive elements). Light 756 can be incident on and reflected by a different section of a layer that includes polarization-sensitive elements that reflect polarized light, as shown.

[0146] As illustrated in Figure 13D, each layer may be disposed at an acute angle relative to the surface of polarization-sensitive reflector 716. For example, the surface of each layer (e.g., the interface between two layers) may form a lateral angle with the surface of polarization-sensitive reflector 716. Additional and / or alternative features of polarization-sensitive reflector 716 are disclosed, for example, with respect to Figure 28D below. To balance the form factor of the illumination system (e.g., illumination system 1000) and the intensity of light reflected by polarization-sensitive reflector 716, the lateral angle may be 5 o ~65 o In some embodiments, the lateral angle may be 10 o ~35 o In some embodiments, for example, as illustrated in FIG. 13D, the lateral angle may be 21 o is.

[0147] The polarization-sensitive reflector 716 may be positioned at an oblique angle relative to another element or surface in the illumination system (e.g., illumination system 1000), such as the first surface 113A of the waveguide 112. The oblique angle may be an acute angle. In some embodiments, the oblique angle is 5 o ~80 o In some embodiments, the angle may be 10 o ~45 o In some embodiments, for example, as illustrated in FIG. 13D, the tilt angle may be 24 o In some embodiments, the tilt angle may be the same as the tilt angle (or wedge angle) "α."

[0148] To increase or maximize the efficient light output from an illumination system (e.g., illumination system 1000), or for other reasons, it may be advantageous to direct light toward a spatial light modulator (e.g., SLM 106) at a particular angle. To achieve this goal, the sum of the lateral angle and the tilt angle may be less than 25°. o ~65 oIn some embodiments, for example, as illustrated in Figure 13D, the sum of the angles may be 45° for light reflected from the end reflector 114 parallel to the first surface 113A. o In such an embodiment, light (e.g., a majority of the light) reflected from an end reflector (e.g., end reflector 114) may be configured to be reflected by polarization-sensitive reflector 716 at an angle relative to the normal to the spatial light modulator (e.g., spatial light modulator 106).

[0149] 14A-14B illustrate a polarizing coating including liquid crystals, such as cholesteric liquid crystals, according to some embodiments. The polarizing coating may include a cholesteric liquid crystal (CLC) element, such as a CLC grating, according to some embodiments. For example, in various implementations, as shown in FIG. 14A , the liquid crystal element 816 includes one or more liquid crystal reflective elements including liquid crystals. For example, the liquid crystal element 816 may include one or more cholesteric liquid crystal reflective elements, including cholesteric liquid crystals, in various implementations. The liquid crystal reflective element 816 may include one or more layers of liquid crystals, such as one or more layers of cholesteric liquid crystals. The liquid crystal layer and liquid crystal reflective element 816 may be polarization-selective, reflecting one polarization state and transmitting another polarization state. Additionally, the liquid crystal layer and liquid crystal reflective element 816 may be wavelength-selective, reflecting certain wavelengths and transmitting other wavelengths. Thus, such optical element 816 may operate on a specific wavelength or range of wavelengths and specific polarization states. Similarly, light having a particular polarization and color (e.g., red, green, blue) reflected from an end reflector (e.g., end reflector 114) may be acted upon by, e.g., reflected by, cholesteric liquid crystal reflective element 816. However, light not within that wavelength range and not in that polarization state may pass through the cholesteric liquid crystal reflective element.

[0150] FIG. 14B shows a cholesteric liquid crystal element 816 including a stack of cholesteric liquid crystal layers 824, 826, and 828. Different layers 824, 826, and 828 in the stack may include cholesteric liquid crystal gratings configured for specific wavelengths or ranges of wavelengths. For example, the first cholesteric liquid crystal layer 824 may be configured to reflect a first color of light 834 (e.g., red light) having a specific polarization state. The second cholesteric liquid crystal layer 826 may be configured to reflect a second color of light 836 (e.g., green) having a specific polarization state. Similarly, the third cholesteric liquid crystal layer 828 may be configured to reflect a third color of light 838 (e.g., blue) having a specific polarization state. Light of a different color than that which the corresponding cholesteric liquid crystal layer 824, 826, and 828 is configured to reflect may pass through the corresponding layer until it reaches the layer 824, 826, and 828 configured to reflect light of that color, for example. The use of multiple layers that interact with different colors allows multiple wavelengths to be redirected and illuminate the SLM 106 .

[0151] 15 illustrates coating locations of a polarizing beam splitter, according to some embodiments. The polarization-sensitive reflector 116 may include, for example, a polarizing coating 602. In some embodiments, the polarizing coating 602 may be coated on the waveguide 112. Thus, the polarizing coating 602 may be disposed between the waveguide 112 and the refractive optical element 118. In some embodiments, the polarizing coating 602 may be adjacent to the waveguide 112. In some embodiments, the polarizing coating 602 may also be disposed adjacent to the refractive optical element 118. In some embodiments, the polarizing coating 602 may be disposed in the optical path between the end reflector 114 and the SLM 106. In some embodiments, the polarization-sensitive reflector 116 may include the polarizing coating 602, for example, on a layer within the polarization-sensitive reflector 116. The polarizing coating 602 may be configured to reflect light having a first polarization state (e.g., s-polarized) and transmit light of a second polarization state, which may be orthogonal polarization (e.g., p-polarized).

[0152] The end reflector 114 may include a reflective coating 604. The reflective coating 604 may be coated on a surface of the waveguide 112, such as on a surface opposite and / or further from the illumination module 102 (not shown in FIG. 15 ). The surface on which the reflective coating 604 is formed / coated may be curved to provide the curved end reflector 114, discussed above. The end reflector 114 may thus have optical power and, in some embodiments, may be positioned relative to the illumination module 102 such that light from the illumination module 102 that is incident on the reflective coating 604 after reflection therefrom (e.g., a majority of this light) is collimated. The reflective coating 604 may be a highly reflective (e.g., mirror) coating and, in various implementations, may include a metal and / or a dielectric material and, in some implementations, may be a multi-layer coating. The reflective coating 604, in some implementations, may be configured to reflect greater than 90%, 95%, or 99% of the light (e.g., visible light) incident thereon.

[0153] One or more surfaces of the PBS 104 may include an anti-reflective coating, such as anti-reflective coatings 606, 607, 608, configured to reduce reflection of incident light. The anti-reflective coating 606 may be disposed on the first surface 113A of the waveguide 112. The anti-reflective coating 607 may also be disposed on the light input surface 113C. Such an anti-reflective coating 607 may reduce input losses due to reflection of light emitted by the lighting module 102 by the light input surface 113C of the waveguide.

[0154] Anti-reflective coating 608 may be disposed on refractive optical element 118, for example, on the surface opposite polarization-sensitive reflector 116 and / or opposite first surface 113A of waveguide 112 and / or opposite anti-reflective coating 606. Anti-reflective coating 608 may increase the exit efficiency of modulated light from PBS 104 and reduce back-reflection onto SLM 106, thus increasing the efficiency of operation of PBS 104.

[0155] The antireflective coatings 606, 607, 608 may be configured to reduce the amount of reflection by at least 50%, 70%, 90%, or more (or any range between any of these values) compared to the reflection without the coating. In some embodiments, the antireflective coatings 606, 607, 608 may reduce the reflection from the coated surface by 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.01%, or less (or any range between any of these values), for example, for a particular design wavelength. In some designs, the antireflective coatings 606, 607, 608 may include a multi-layer coating and include at least two coating layers. The antireflective coating may include an interference coating. One or more of the antireflective coatings 606, 607, 608 may be a broadband antireflective coating.

[0156] Light reflected from the end reflector 114 may first propagate toward the polarization-sensitive reflector 116. As explained above, some light may be transmitted through the polarization-sensitive reflector 116 (e.g., depending on the polarization of the light). Light transmitted from the end reflector 114 through the polarization-sensitive reflector 116 may be incident on a surface 614 of the refractive optical element 118, which has a blackening coating 615. The refractive optical element 118 may include a blackening coating 615 to reduce back-reflection of light incident thereon. For example, the blackening coating 615 may be coated on the surface 614 of the refractive optical element 118 opposite the end reflector 114 of the waveguide 112. The blackening coating 615 may be disposed on the surface 614 that is coplanar with the light input surface 113C. The surface 614 on which the blackening coating 615 is disposed may be perpendicular to the first surface 113A and / or the SLM 106. In some implementations, a blackening coating 615 may be disposed on the surface 614 perpendicular to the second surface 113B of the refractive optical element 118. The blackening coating 615 may also be configured to prevent reflection of light. For example, the blackening coating 615 may include a black dye or pigment. As discussed above, the blackening coating 615 may be positioned to receive light from the end reflector 114. Thus, the blackening coating 615 may be configured to absorb light reflected from the end reflector 114.

[0157] FIG. 16 illustrates features of a polarizing beam splitter (e.g., PBS 104) according to some embodiments. As shown, waveguide 112 is wedge-shaped with second surface 113B tilted relative to light input surface 113C. Wedge angle 502 describes the inclination of second surface 113B relative to first surface 113A. While the wedge is often triangular, a wedge-shaped waveguide 112 may be truncated to create light input surface 113C, which may be used to input light into waveguide 112. Thus, in this example, the intersection of the plane defined by the two surfaces may occur outside of PBS 104, as shown in FIG. 16, for example. Other configurations are also possible. In some embodiments, wedge angle 502 is an acute angle. For example, wedge angle 502 may be approximately 5°. o ~55 o In some embodiments, the wedge angle 502 may be approximately 8 o ~35 o In some embodiments, the wedge angle 502 is 18 o As discussed above, the light input surface 113C may provide an input surface or input face 504 for introducing light into the waveguide 112. The input face 504 may be located along the light input surface 113C, although input faces located elsewhere may also be utilized in other geometries and configurations. In some embodiments, the input face is located toward the base of the PBS 104, such as the first surface 113A of the waveguide 112. Thus, the input face 504 may include a transparent surface, although, as discussed above, a blackening coating 615 may be included on one or more nearby surfaces of the refractive optical element 118. In some embodiments, the height of the input face 504 may be approximately the height of the surface 113C. In some embodiments, the input face 504 and / or light input surface 113C is smaller, e.g., less than ½, ⅓, ¼, ⅕, ⅙, ⅛, ⅛, ⅙-tenth, or ⅙-twentieth the size of the end reflector 114 (or any value within any range defined by any of these values). The end reflector 114 may have optical power 506, e.g., to collimate light emitted through the input face 504 that is incident on the end reflector 114. Lighting Module

[0158] 17A-17H illustrate example configurations of the illumination module 102 relative to the PBS 104, according to some embodiments. For example, FIGS. 17A-17H illustrate various configurations and / or orientations of the illumination module 102 relative to the light input surface 113C and variations in the configuration and / or orientation of the light input surface 113C. The illumination module 102 may have a central optical axis that may be perpendicular to the output surface of the illumination module 102 through which light is emitted. The light input surface 113C may also have a normal. In FIG. 17A, the optical axis of the illumination module 102 is parallel to the surface axis of the light input surface 113C. The output face of the illumination module 102 may be butt-coupled to the light input surface 113C, as shown. In some embodiments, such as that shown in FIG. 17A, the surface axis (e.g., optical axis, central axis, etc.) of the light input surface 113C is parallel to the surface (e.g., first surface 113A) of the waveguide 112. In some embodiments, the surface axis (e.g., surface normal) of light input surface 113C is perpendicular to a surface (e.g., the surface opposite refractive optical element 118 and / or the output area and / or first surface 113A) of waveguide 112. In some embodiments, the surface axis of light input surface 113C is not parallel to any surface of waveguide 112.

[0159] 17B and 17C illustrate examples in which the surface axis of the illumination module 102 is neither parallel nor perpendicular to the surface axis of the light input surface 113C. The angle formed between the illumination module 102 and the light input surface 113C may define an acute angle. As shown by FIG. 17B, the light input surface 113C may form an obtuse angle with the surface of the waveguide 112 opposite the polarization-sensitive reflector 116 and / or opposite the refractive optical element 118 and / or the surface closest to the SLM 106. As shown by FIG. 17C, the light input surface 113C may form an acute angle with the surface of the waveguide 112 opposite the polarization-sensitive reflector 116 and / or opposite the refractive optical element 118 and / or the surface closest to the SLM 106. In some embodiments, light input surface 113C forms a right angle with the surface of waveguide 112 opposite polarization-sensitive reflector 116 and / or opposite refractive optical element 118 and / or the surface closest to SLM 106, as illustrated, for example, in FIG. 17A . Also, in both FIGS. 17B and 17C , light input surface 113C is tilted with respect to illumination module 102. Similarly, the surface axis of illumination module 102 may not be parallel to the normal to light input surface 113C. As a result of the tilt, an air gap is disposed between light input surface 113C and illumination module 102. As a result of the tilt, this air gap is asymmetric.

[0160] FIG. 17D illustrates a configuration of the PBS 104 that includes a deflecting element 954. The deflecting element 954 may include a reflective and / or diffractive element. For example, the deflecting element 954 may include a mirror and / or a grating. As shown, the illumination module 102 launches light into the surface of the waveguide 112 opposite the polarization-sensitive reflector 116 and / or opposite the refractive optical element 118 and / or the surface closest to the SLM 106. In some embodiments, the light is launched into the surface of the PBS 104 opposite the refractive optical element 118 and / or closest to the SLM 106. In some embodiments, the light is launched into the surface of the PBS 104 proximate to the refractive optical element 118. In the implementation illustrated in FIG. 17D, the waveguide 112 is longer than the refractive optical element 118, but the design need not be so limited. The deflecting element 954 is disposed on a portion of the waveguide 112, in this example, on an angled surface opposite the first surface 113A at the narrowest portion or apex of the wedge. Thus, the deflecting element 954 is angled, and together with the angled surface on which the deflecting element 954 is disposed, it forms an acute angle with the first surface 113A of the waveguide 112. Light can be redirected using the deflecting element 954. The deflecting element 954 directs the light and may propagate toward the end reflector 114, which in some configurations may be curved and / or have optical power and may collimate the light. The deflecting element 954 may include an interference coating and / or a dielectric coating, such as metallization. Such a coating may provide, for example, reflection.

[0161] 17E and 17F illustrate examples of configurations in which the surface axis of the illumination module 102 is parallel to the surface axis of the light input surface 113C (e.g., parallel to the normal to the surface of the light input surface 113C). FIG. 17E illustrates how the light input surface 113C can form an obtuse angle with the surface of the waveguide 112 opposite the polarization-sensitive reflector 116 and / or opposite the refractive optical element 118 and / or the surface closest to the SLM 106. FIG. 17F illustrates how the light input surface 113C can form an acute angle with the surface of the waveguide 112 opposite the polarization-sensitive reflector 116 and / or opposite the refractive optical element 118 and / or the surface closest to the SLM 106. In the implementations illustrated in FIGS. 17E and 17F, the illumination module 102 is butted against the light input surface 113C (e.g., with no gap therebetween). The illumination module 102 may then be tilted such that a surface axis of the illumination module 102 is angled relative to the first surface 113A of the waveguide 112.

[0162] FIG. 17G illustrates a configuration of the PBS 104 that includes a deflecting element 954. The deflecting element 954 may include a reflective and / or diffractive element. For example, the deflecting element 954 may include a mirror and / or a grating. As shown, the illumination module 102 launches light into a surface of the waveguide 112 that is proximate to the refractive optical element 118. The light can be redirected using the deflecting element 954, for example, toward the end reflector 114. In the implementation illustrated in FIG. 17G, the waveguide 112 is longer than the refractive optical element 118, but the design need not be so limited. The deflecting element 954 is disposed on a portion of the waveguide 112, in this example, on a sloped surface at the narrowest portion of the wedge or at the apex of the wedge. Thus, the deflecting element 954 is sloped and, together with the sloped surface on which the deflecting element is disposed, forms an obtuse angle with the first surface 113A of the waveguide 112. The deflecting element 954 may direct the light, be curved, and / or have optical power, causing it to propagate toward the end reflector 114, which may collimate the light. The deflecting element 954 may include an interference coating and / or a dielectric coating, such as metallization. Such a coating may provide, for example, reflection.

[0163] 17H illustrates a PBS 104 with an input turning feature 956 configured to redirect light introduced into the waveguide 112. The turning feature 956 is disposed on the surface opposite the end reflector 114. The turning feature 956 is shown disposed on the light input surface 113C. Light launched into the waveguide 112 by the illumination module 102 propagates through the turning feature 956 toward the end reflector 114 and is redirected and possibly bent by refraction and / or diffraction. The turning feature 956 may potentially include microprismatic and / or nanoprismatic structures (e.g., gratings). In some implementations, the turning feature 956 may include a tilted tilt surface that, for example, refracts light incident thereon, bends light transmitted therethrough, and redirects light exiting the tilted tilt surface. In some embodiments, turning feature 956 may include, for example, a grating or diffractive feature that refracts light incident thereon, bends light transmitted therethrough, and redirects light exiting the grating or diffractive feature. One or more surfaces of turning feature 956 intersect light input surface 113C and may be optically transmissive to visible light and operate in a transmissive manner.

[0164] 18A-18M illustrate example configurations of an illumination module (e.g., illumination module 102) according to some embodiments. FIG. 18A shows three light emitters 1002a, 1002b, and 1002c that inject light into a color-mixing element 1004. The color-mixing element 1004 may be included within a dichroic combiner or a beam combiner (see below). Each light emitter 1002a, 1002b, 1002c may emit a different color. For example, the first light emitter 1002a may be configured to emit light of a first color (e.g., red), the second light emitter 1002b may be configured to emit light of a second color (e.g., green), and the third light emitter 1002c may be configured to emit light of a third color (e.g., blue). Other configurations are also possible. The various light beams may travel and overlap within the beam combiner. One or more of the light emitters 1002a, 1002b, and 1002c may include one or more LEDs. For example, each light emitter may have exactly one LED or more. However, other configurations (e.g., using lasers) may be used. In some cases, it may be advantageous for one or more of the light emitters 1002a, 1002b, and 1002c to emit coherent light. For example, one or more of the light emitters 1002a, 1002b, and 1002c may include a laser element, such as a laser diode.

[0165] The color mixing element 1004 may include a prism structure. For example, the color mixing element 1004 may include an x-cube. The x-cube includes a first dichroic beam combiner element 1006a and a second dichroic beam combiner element 1006b within the prism structure. One or more of the dichroic beam combiner elements 1006a, 1006b may include an optical film or other structure configured to reflect light having certain wavelengths and transmit light having certain wavelengths. Light from the first emitter 1002a is reflected by the first dichroic beam combiner element 1006a, and light from the third emitter 1002c is reflected by the second dichroic beam combiner element 1006b. Light from the second emitter 1002b may be transmitted by both the first and second dichroic beam combiners. Thus, light from the first, second, and third emitters 1002a, 1002b, 1002c is combined. The emitters 1002a, 1002b, 1002c may be butt-coupled to the color mixing element 1004, as shown in FIG. 18A . Other configurations are also possible. As shown in various figures discussed above, including the illumination module 102, the output surface of the color mixing element 1004 is optically coupled to the light input surface of the waveguide (e.g., light input surface 113C of waveguide 112) opposite the end reflector (e.g., end reflector 114). The light from the three emitters 1002a, 1002b, 1002c, combined by the color mixing element 1004, is thus launched into the waveguide 112 and propagates toward the end reflector 114.

[0166] 18B shows a first light emitter 1002a that injects light into a first color mixing element 1004a and second and third light emitters 1002b, 1002c that inject light into a second color mixing element 1004b. The first color mixing element 1004a and / or the second color mixing element 1004b may include a prism or prism structure, such as a dichroic prism. The first color mixing element 1004a and / or the second color mixing element 1004b may include a dichroic beam combiner element. The dichroic beam combiner element may include a film or other optical structure that reflects light having certain wavelengths and transmits light having certain wavelengths. Light from a first emitter 1002a (possibly of a first color) is reflected by a first dichroic beam combiner element, and light from a second emitter 1002b (possibly of a second color) is reflected by a second dichroic beam combiner element. Light from a third emitter 1002c (possibly of a third color) may be transmitted by both the first and second dichroic beam combiners. Thus, light from the first, second, and third emitters 1002a, 1002b, 1002c is combined. One or more of the emitters 1002a, 1002b, 1002c may be butt-coupled to one or more color mixing elements, e.g., input surfaces of the color mixing elements, as shown in FIG. 18B, although other configurations are possible. As shown, the output surface of the second color mixing element 1004b is optically coupled to the input surface of the first color mixing element 1004a. The output surface of the first color mixing element 1004a may be optically coupled to the light input surface of the waveguide (e.g., light input surface 113C of the waveguide 112) opposite the end reflector (e.g., end reflector 114). Light from the three emitters 1002a, 1002b, 1002c combined by the color mixing elements 1004a, 1004b is thus launched into the waveguide 112 and propagates toward the end reflector 114. In some embodiments, the first color mixing element 1004a and the second color mixing element 1004b are adjacent to each other.The color mixing elements 1004a, 1004b may each include a dichroic reflector, a dichroic beam combiner, or a mirror, possibly with a dichroic coating. As discussed above, the color mixing elements 1004a, 1004b may be configured to reflect (e.g., be tuned to) certain wavelengths of light and / or transmit light of different wavelengths. For example, the first color mixing element 1004a may be tuned to blue light (e.g., configured to reflect blue light), and the second color mixing element 1004b may be tuned to green light (e.g., configured to reflect green light).

[0167] FIG. 18C shows an illumination module 102 similar to that shown in FIG. 18B, including color mixing elements 1004a, 1004b and light emitters 1002a, 1002b, 1002c. FIG. 18C shows a first light emitter 1002a that inputs light into the first color mixing element 1004a, and second and third light emitters 1002b, 1002c that input light into the second color mixing element 1004b. The light emitters 1002a, 1002b, 1002c may include any type of light emitter described herein (e.g., LED, laser, OLED, etc.). However, as shown, one or more of the light emitters 1002a, 1002b, 1002c may be spaced apart from the corresponding color mixing elements 1004a, 1004b. The light from the three emitters 1002a, 1002b, 1002c combined by the color mixing elements 1004a, 1004b is thus input into the waveguide 112 and propagates toward the end reflector 114. The illumination module 102 shown in FIG. 18C may include a diffuser 1008. In some embodiments, the emitters 1002a, 10,02b, 1002c may be configured to create an occupied area of potentially divergent light (e.g., R, G, B) that overlaps on the diffuser 1008. For example, as shown, the light emitters 1002a, 1002b, 1002c, the color mixing elements 1004a, 1004b, and the diffuser 1008 may be arranged along the same optical path such that the diffuser 1008 receives light from the light emitters 1002a, 1002b, 1002c. The diffuser 1008 may diffuse the light from the emitters 1002a, 1002b, 1002c and provide a more uniform intensity of light across the spatial area. In some embodiments, for example, the diffuser 1008 may reduce the likelihood of a "hot spot" including an observable intensity peak. The diffuser 1008 may also assist, for example, in mixing together the light of different light emitters 1002a, 1002b, 1002c within the waveguide 112 that receives light from the illumination module 102. In some embodiments, the diffuser 1008 may also diverge the beam incident thereon. The diffuser 1008 can thus provide an emission cone useful for a head-mounted display system that can be in optical communication with it.

[0168] 18D shows a design similar to that of FIG. 18C that includes optics, such as beam-shaping optics (e.g., collimating optics), that may be included to shape the beams of light entering the color-mixing elements 1004a, 1004b. The beam-shaping optics may include, for example, lenses 1012a, 1012b, 1012c. One or more of the lenses 1012a, 1012b, 1012c may be configured to focus the light (e.g., have positive refractive power). The lenses 1012a, 1012b, 1012c may be configured to reduce the divergence of light from the individual emitters 1002a, 1002b, 1002c so that the light is more efficiently coupled into the color-mixing elements 1004a, 1004b. The lenses 1012a, 1012b, and 1012c may be collimating lenses configured to collimate light from the corresponding emitters 1002a, 1002b, and 1002c, for example. The lenses 1012a, 1012b, and 1012c may form collimated beams from light emitted by the light emitters 1002a, 1002b, and 1002c, respectively, which may overlap within the color mixing elements 1004a, 1004b and / or dichroic beam combiners and / or diffusers, for example. In some embodiments, the lenses 1012a, 1012b, and 1012c may have negative refractive power. In some embodiments, the refractive power and position of the lenses 1012a, 1012b, and 1012c may be configured to create, for example, a diverging light cone entering the waveguide 112. The lenses 1012a, 1012b, 1012c can help control the amount of divergence and provide a suitable cone of diverging light. Each of the lenses 1012a, 1012b, 1012c may be positioned between the corresponding light emitter 1002a, 1002b, 1002c and one or more of the color mixing elements (e.g., color mixing elements 1004a, 1004b). In some designs, a diffuser 1008 is included within the lighting module 102, as shown in FIGS. 18C-18D.As shown, the light emitters 1002a, 1002b, 1002c, the lenses 1012a, 1012b, 1012c, the color mixing elements 1004a, 1004b, and the diffuser 1008 may be arranged along the same optical path such that the diffuser 1008 receives light from the light emitters 1002a, 1002b, 1002c.

[0169] 18A-18D show an illumination module including color mixing elements 1004a, 1004b, which include aligned prisms, such as aligned prism cubes. The prisms may be, for example, right-angle prisms. Each prism can receive two inputs and has one output. The prisms may include a material that is substantially transparent to visible light, and may include plastic or glass. As discussed above, the prisms include wavelength-selective filters, such as dichroic filters, that reflect certain wavelengths and transmit other wavelengths.

[0170] 18E-18G illustrate an exemplary embodiment of the illumination module 102 that includes a turning mirror 1004c in addition to color mixing elements 1004a and 1004b. In the illustrated example, the turning mirror 1004c includes a prism or a portion thereof. The color mixing elements 1004a and 1004b may include a prism, such as a dichroic beam combiner prism as described above. The turning mirror 1004c has an angled reflective surface for redirecting the light beam. The angled reflective surface may be angled, for example, about 30° to 60° relative to one of the other sides of the prism, and in some embodiments, about 45°. Thus, the turning mirror 1004c may include, for example, a 45° prism. The turning mirror 1004c may include a prism that redirects light by total internal reflection. The redirecting mirror 1004c may comprise an optically transmissive material, such as glass or plastic, that provides total internal reflection. The redirecting mirror 1004c and the color mixing elements 1004a, 1004b may be aligned along an optical path (e.g., along the same optical axis), as shown in Figures 18E-18G. The light emitters 1002a, 1002b, and 1002c may each be positioned adjacent to a corresponding color mixing element. Thus, light from the light emitters 1002a, 1002b, and 1002c may be coupled into the individual redirecting mirror 1004c and color mixing elements 1004a, 1004b. The light is thereby combined and directed along a common optical path. In some embodiments, such as shown in Figure 18F, the light emitters 1002a, 1002b, and 1002c may be spaced apart from the corresponding color mixing elements 1004a, 1004b. As shown in Figure 18G, lenses 1012a, 1012b, 1012c may be included. Also, as shown in Figures 18F and 18G, the lighting module 102 may include a diffuser 1008. Various features and characteristics of the lenses, diffusers, and color-mixing elements 1004a, 1004b are discussed herein. Thus, any such features or characteristics discussed herein can be applied to these structures.

[0171] 18H-18M illustrate example embodiments of an illumination module 102 similar to those illustrated in FIGS. 18B-18G, respectively; however, the illumination module 102 is tapered. FIGS. 18H-18J show an illumination module 102 including color-mixing elements 1004a, 1004b, such as dichroic prisms, where one prism is larger than the other. Similarly, one end of each color-mixing element 1004a, 1004b is larger than the other end of the same color-mixing element 1004a, 1004b. The color-mixing elements 1004a, 1004b are arranged such that the small end of one color-mixing element 1004a is adjacent to or closest to the large end of the other color-mixing element 1004b. In some implementations, such as those shown in Figures 18H-18J, the color mixing elements 1004a, 1004b have one end that is larger than the other end, resulting in one or more tilted input surfaces. The one or more tilted input surfaces of each color mixing element 1004a, 1004b may be located on the same side of the lighting module 102, and together may create a larger tilted surface, which in some implementations may be smooth. As shown in Figures 18H-18J, the tilted input surfaces 1018a, 1018b may be coplanar with each other. These tilted input surfaces 1018a, 1018b may correspond to the input surfaces of the color mixing elements 1004a, 1004b. Input surface 1018c may correspond to the input surface of color mixing element 1004b. Light emitters 1002a, 1002b may be positioned relative to these tilted input surfaces 1018a, 1018b, and light emitter 1002c may be positioned relative to input surface 1018c to inject light into color mixing elements 1004a, 1004b through these tilted input surfaces 1018a, 1018b, 1018c. The lighting module 102 may thus be tapered, with one end larger than the other end. The side opposite the tilting surfaces need not be tilted. The tilting surfaces 1018a, 1018b may be non-parallel to one or more surfaces on the opposite side of the lighting module 102, as illustrated in Figures 18H-18J.

[0172] In various implementations, the color mixing elements 1004a, 1004b include tilted surfaces, possibly including dichroic beam combiners, that direct light from the emitters 1002a, 1002b, 1002c along a common optical path. The color mixing elements 1004a, 1004b are arranged along this optical path. In various implementations, the tilted input surfaces 1018a, 1018b are tilted relative to this optical path.

[0173] Figures 18K-18M illustrate an example embodiment of an illumination module 102 that includes a turning mirror 1004c in addition to color mixing elements 1004a, 1004b in a configuration similar to that shown in Figures 18E-18G. However, the illumination module 102 shown in Figures 18K-18M is tapered, like that in Figures 18H-18J. Thus, the discussion above regarding Figures 18H-18J applies to the tapered illumination module 102 shown in Figures 18K-18M.

[0174] 18K-18M show an illumination module 102 including color-mixing elements 1004a, 1004b, such as dichroic prisms, where one prism is larger than the other. Similarly, one end of each color-mixing element 1004a, 1004b is larger than the other end of the same color-mixing element 1004a, 1004b. The color-mixing elements 1004a, 1004b are arranged so that the small end of one color-mixing element 1004a is adjacent to or closest to the large end of the other color-mixing element 1004b. The turning mirror 1004c may also include a prism with an angled reflective surface for redirecting the light beam, positioned adjacent to or closer to the smaller end of the other color-mixing element 1004b.

[0175] In some embodiments, such as those shown in Figures 18K-18M, the color mixing elements 1004a, 1004b have one end that is larger than the other end, resulting in angled input surfaces 1018a, 1018b. The angled input surfaces 1018a, 1018b of each color mixing element 1004a, 1004b may be located on the same side of the lighting module 102, and together may create a larger angled surface, which in some embodiments may be smooth. The emitters 1002a, 1002b, 1002c may be positioned relative to these angled input surfaces 1018a, 1018b to inject light into the color mixing elements 1004a, 1004b through these angled input surfaces 1018a, 1018b. The lighting module 102 may therefore be tapered, resulting in one end that is larger than the other end. The side opposite the angled surface need not be angled. The tilted input surfaces 1018a, 1018b may be non-parallel to one or more surfaces on the opposite side from the lighting module, as illustrated in Figures 18K-18M.

[0176] The turning mirror 1004c may have a surface 1016 that is angled to receive light from the individual light emitter 1002c and reflect the light to the nearby mixing element 1004b. The turning mirror 1004c may also include an angled input surface 1018c positioned relative to the individual light emitter 1002c to receive light therefrom. As described above, this light is reflected by the surface 1016. The angled input surface 1018c may be positioned on the same side of the lighting module 102 as the other angled input surfaces 1018a, 1018b of each color mixing element 1004a, 1004b, and together may create a larger angled surface, which may be smooth in some implementations. Similarly, as shown in FIGS. 18K-18M, the input surfaces 1018a, 1018b, 1018c may each be positioned flush with one another.

[0177] 18K-18M, in some embodiments, the color mixing elements 1004a, 1004b may include tilted surfaces, possibly including dichroic beam combiners, that direct light from the emitters 1002a, 1002b along a common optical path. The color mixing elements 1004a, 1004b are arranged along this optical path. In various implementations, the tilted input surfaces 1018a, 1018b, 1018c are tilted relative to this optical path.

[0178] The taper of the lighting module 102 may, in some embodiments, track the divergence of light from the emitters 1002a, 1002b, 1002c. For example, the tilted input surfaces 1018a, 1018b, 1018c may have a tilt angle that is at least as large as the divergence angle of the light beams propagating through the color mixing elements 1004a, 1004b. However, other amounts of taper and other configurations are possible.

[0179] Other characteristics of the illumination module 102, the light emitters 1002a, 1002b, and 1002c, and the color mixing elements 1004a and 1004b, and their arrangement may be similar to those described above with respect to Figures 18B-18M. For example, the color mixing elements 1004a and 1004b may include prisms, such as dichroic prisms, with dichroic beam combiners that reflect certain wavelengths of light and transmit other wavelengths of light. At least one of the light emitters 1003c may be butt-coupled to a respective color mixing element 1004b. In some implementations, the light emitters 1002a, 1002b, and 1002c can be separated from the color mixing elements 1004a and 1004b by a gap. In some embodiments, one or more lenses may be disposed between the light emitters 1002a, 1002b, and 1002c, which may be spaced apart from the color mixing elements 1004a and 1004b. Additionally, in some embodiments, the lighting module 102 includes a diffuser 1008. The features and characteristics of the lighting module 102, the color mixing elements 1004a, 1004b, the lenses 1012a, 1012b, and 1012c, and the diffuser 1008 are discussed above. Thus, any such features or characteristics discussed herein can be applied to these structures. Advantageously, light from the different colored light emitters 1002a, 1002b, and 1002c is combined and mixed together within the color mixing elements 1004a and 1004b.

[0180] Another configuration including one or more dichroic beam combiner elements is shown in FIG. 18N. FIGS. 18N-18P illustrate arrangements configured to combine and / or mix different colored light from different colored light sources. As shown, the lighting device 1400 may include one or more wavelength-dependent light redirecting elements. The one or more wavelength-dependent light redirecting elements may include a dichroic coating or layer. In some designs, the wavelength-dependent light redirecting element includes a color combining or color mixing element 1666 (e.g., an x-cube).

[0181] 18N shows three light emitters 1002a, 1002b, and 1002c. Each light emitter 1002a, 1002b, and 1002c may correspond to a different color (e.g., red, blue, and green). The light emitter 1002a may combine the different colored light from the light emitters 1002a, 1002b, and 1002c and launch light into a color-mixing element 1004, including wavelength-dependent combining elements 1006a, 1064b, disposed within the illumination module 102 to redirect the light toward the end reflector 114. In some implementations, the color-mixing element 1004, including combining elements 1006a, 1064b, can be separate from and disposed relative to the waveguide 112. The combining elements 1006a, 1006b may include a dichroic coating. Light may be injected into a surface of the waveguide 112 opposite the end reflector 114. Light emitter 1002a is positioned to inject light into a surface of the color mixing element 1004 opposite (e.g., furthest from) the end reflector 114. Light emitters 1002b, 1002c may inject light into a surface of the color mixing element 1004 that is parallel to and / or adjacent to the surface of the waveguide 112 closest to the SLM (bottom surface) (not shown). As shown, light emitters 1002b, 1002c may inject light into a surface of the color mixing element 1004 opposite (e.g., furthest from) the refractive optical element 118. Light from the first emitter 1002a is transmitted through the dichroic combining element 1006a, while light from the second emitter 1002b is reflected from the first dichroic combining element 1006a, such that light from the first and second emitters 1002a, 1002b is combined and propagates along the same path to the second combining element 1006b, where light from the third emitter 1002c is combined with the combined light from the first and second emitters 1002a, 1002b.

[0182] As shown, the first and second dichroic combining elements 1006a, 1006b are tilted, for example, with respect to the surface of the bottom waveguide 112 opposite the refractive optical element 114. The light emitter 1002a and the first and second dichroic combining elements 1006a, 1006b are disposed along an optical path, and the first and second dichroic combining elements 1006a, 1006b are also tilted, for example, with respect to the optical path. The first and second dichroic combining elements 1006a, 1006b are tilted at an angle with respect to the bottom surface of the color mixing element 1004 (e.g., closest to the SLM (not shown)). This tilt angle is acute in the implementation shown in FIG. 18N.

[0183] Figure 18O shows three light emitters 1002a, 1002b, and 1002c in a different configuration than Figure 18N. Each light emitter 1002a, 1002b, and 1002c may correspond to a different color (e.g., red, blue, and green). The first light emitter 1002a may launch light into a color-mixing element 1004, including wavelength-dependent combining elements 1006a and 1006b, disposed within the waveguide 112 to redirect light from the light emitters 1002a, 1002b, and 1002c toward the end reflector 114. In some implementations, the color-mixing element 1004, including combining elements 1006a and 1006b, can be separate from and disposed relative to the waveguide 112. The combining elements 1006a and 1006b may include a dichroic coating. Light from the first emitter 1002a may be injected into the surface of the color mixing element 1004 opposite (e.g., furthest from) the end reflector 114. Light emitters 1002b, 1002c may inject light into the surface of the color mixing element 1004 on the side opposite (e.g., furthest from) the SLM of the color mixing element 1004.

[0184] Light from the first emitter 1002a may be incident on and transmitted through the first combining element 1006a, reflected from the first combining element 1006a, and combined with light from the second light emitter 1002b propagated to the second combining element 1006b. Light from the first and second light emitters 1002a, 1002b is transmitted through the second light combining element 1006b. Light from the third light emitter 1002c is reflected from the second light combining element 1006b and combined with light from the first and second light emitters 1002a, 1002b. The combined light from the three emitters 1002a, 1002b, 1002c may be launched into the surface of the waveguide 112 opposite the end reflector 114.

[0185] As shown, the first and second dichroic combining elements 1006a, 1006b are tilted, for example, with respect to the bottom surface of the waveguide 112 opposite the end reflector 114. The light emitter 1002a and the first and second dichroic combining elements 1006a, 1006b are disposed along an optical path, and the first and second dichroic combining elements 1006a, 1006b are also tilted, for example, with respect to the optical path. The first and second dichroic combining elements 1006a, 1006b are tilted at an angle with respect to the bottom surface (e.g., closest to the SLM) of the color mixing element 1004. This tilt angle is obtuse in the implementation shown in FIG. 18O.

[0186] 18P shows three light emitters 1002a, 1002b, and 1002c that inject light into another color mixing element 1004. The color mixing element 1004 may include an x-cube. The x-cube includes first and second dichroic beam combiner elements 1006a and 1006b. Light from the first emitter 1002a is reflected by the first dichroic beam combiner element 1006a, and light from the second emitter 1002b is reflected by the second dichroic beam combiner element 1006b. Light 1002c from a third emitter may be transmitted by both the first and second dichroic beam combiner elements 1006a and 1006b. Thus, light from the first, second, and third emitters 1002a, 1002b, and 1002c is combined. As shown, the output surface of the color mixing element 1004 is optically coupled to the input surface of the waveguide 112 opposite (e.g., furthest from) the end reflector 114. The light from the three emitters 1002a, 1002b, and 1002c, combined by the x-cube 1004, is thus launched into the waveguide 112 and propagates toward the end reflector 114. Illumination modules 102 having a variety of different configurations are disclosed above. These configurations may include multiple dichroic beam combiner elements. In various configurations, these dichroic beam combiner elements were contained within a prism, such as a dichroic prism (e.g., a dichroic cube prism or a right-angle prism). The dichroic beam combiner elements may be employed differently. Instead of a prism, such as a cube prism, a beam splitter or beam combiner plate may be used. Such a plate may, for example, include a substrate (e.g., a plate, sheet, layer) of a transparent material on which the dichroic beam combiner elements are formed. Such a dichroic beam combiner element may, for example, include a dichroic coating. As explained above, the dichroic beam combiner element may reflect light of certain wavelengths and transmit light of other wavelengths.18Q-18V show illumination modules utilizing beam combiner plates similar to the illumination modules depicted in FIGS. 18B-18M utilizing dichroic (e.g., cube or rectangular prism) prisms. As shown in some implementations, lenses 1012a, 1012b, 1012c (e.g., collimating lenses) are included. Some implementations include a diffuser 1008. Light emitters 1002a, 1002b, 1002c, such as lasers (e.g., laser diodes), may also be included. Thus, the properties, structures, and / or characteristics discussed above and elsewhere herein with respect to illumination modules 102 comprising dichroic (cube or rectangular prism) prisms can be applied to illumination modules comprising beam combiner plates. Still other variations, such as those described elsewhere herein, are also possible.

[0187] As illustrated in FIG. 19 , the illumination system 1800, according to some embodiments, can include a delivery system 1802 between the illumination module 102 and the PBS 104. The delivery system 1802 can be, for example, an optical fiber delivery system. The illumination module 102 can include a coherent light emitter, such as a laser module. The laser module can include one or more lasers, including lasers of different colors. The different lasers can include lasers of one or more colors, such as red, green, and blue. The laser module can also include one or more combiners to combine beams from more than one laser. Such combiners can include one or more beam splitters or combiners, dichroic beam splitters or combiners, and / or optical fiber couplers to combine light from different sources, such as different color sources (e.g., lasers of different colors). The optical fiber delivery system 1802 can include a multimode optical fiber. In some designs, the optical fiber has a sufficiently large core to facilitate mixing of light from different lasers. The optical fiber can also include polarization-maintaining fiber.

[0188] The delivery system 1802 may include two or more fibers. For example, different fibers may be optically coupled to different light sources, such as different color light sources, to launch different colored visible light (e.g., red, green, blue). However, in some embodiments, multiple light emitters, such as multiple colored light sources, are combined into a single fiber. The illumination module 102 may include multiple lasers, such as different colored lasers. The outputs of the illumination module 102 (e.g., different colored lasers) can be optically coupled to a multimode optical fiber. The different colored light from the illumination module 102 may be mixed within the fiber. The color mixing may occur inside the illumination module 102 and / or within the delivery system 1802, such as in embodiments including a multimode laser.

[0189] The illumination module 102, which includes a laser light emitter, may output polarized light, such as light in a first polarization state (e.g., an s-polarized state), which may be modulated by the SLM 106. Thus, the delivery system 1802 may include a polarization-maintaining fiber (PMF). The polarization-maintaining fiber may maintain the polarization state of the light so that the illumination module 102 may efficiently deliver the preferred polarization to the PBS 104.

[0190] The delivery system 1802 is positioned to launch light into the waveguide 112. The delivery system 180 is butt-coupled to the light input surface 113C. In some embodiments, the delivery system 1802 launches light into the waveguide 112 opposite the output area 1804 and / or opposite the refractive optical element 118.

[0191] The flexibility and coupling capability over distance of the delivery system 1802 including optical fibers may facilitate the use of an illumination module 102 including one or more laser modules at a distance remote from the polarizing beam splitter 104. For example, the illumination module 102 (e.g., a laser module) may be disposed on a unit not mounted on or near the user's head, where the PBS 104 may be located. The illumination module 102 may be mounted on a platform that can be worn by the user on a location other than the head. The platform may be mountable, for example, on a belt or in a wearable pack. Providing one or more laser modules in a separate wearable device distinct from the head-mounted device can reduce heat emissions near the user's head, reduce the weight of an associated head-mounted system to be worn by the head, and / or provide more flexibility in the configuration of the associated head-mounted system.

[0192] As discussed above, the illumination module 102 may include one or more coherent light emitters, such as lasers. In some embodiments, the illumination module 102 includes one or more fiber lasers. Lasers can provide relatively high optical output power compared to other light emitters. Coherent light emitters also have narrow spectral bands. Narrow-band coherent light emitters may output light over a narrow range of wavelengths, for example, from about 2 nm to 45 nm. In some embodiments, the wavelength range of narrow-band coherent light emitters is from about 10 nm to 40 nm. In some embodiments, the wavelength range of narrow-band coherent light emitters is from about 20 nm to 30 nm. The coherent light emitter may include multiple such laser sources (e.g., laser sources for red, green, and blue light). Narrow-band coherent light emitters can have increased color saturation, which may be useful for color displays. The increased saturation of coherent light emitters can potentially expand the size of the available color gamut that can be produced using different highly saturated color light emitters.

[0193] In some embodiments, using a fiber can enable smaller optical systems. An optical fiber, which has a smaller output area compared to a large LED, can couple into a smaller input face of the waveguide 112 with reduced coupling losses. The waveguide 112 can therefore potentially be made smaller. Additionally, in some designs, the numerical aperture (NA) of the fiber is configured to increase the incoupling efficiency of the PBS 104. For example, the NA of the fiber provides a narrower cone angle than an LED. The fiber can therefore potentially be used to efficiently incouple light into a smaller waveguide 112. A fiber laser can provide a narrower cone angle across the LED. Additionally, a narrower cone angle can allow for a smaller beam diameter of the light after it is collimated by the end reflector 114. This can improve interoperability with one or more other optical elements to which the waveguide 112 is optically coupled, such as one or more incoupling optical elements 700, 710, 720 (see, e.g., FIG. 9A ). In some designs, the light can be polarized before being incoupling in the waveguide 112 without the need for a pre-polarizer. In some embodiments, the illumination module 102 outputs polarized light and the delivery system 1802 includes a polarization-maintaining fiber (PMF). In these embodiments, a pre-polarizer may not be needed to polarize the light output by the fiber prior to being incoupling into the waveguide 112.

[0194] However, the lighting module 102 need not be limited to lasers. LEDs may also be employed. One or more superluminescent light emitting diodes (SLEDs) may be used in some designs. Different colors of light from LEDs or other light emitters, as well as colors from laser sources, can be mixed. Multimode optical fibers may also be employed.

[0195] The illumination system 1800 may be configured in a transmission mode using coherent light. In the transmission mode, the illumination module 102 launches light into the waveguide 112 via a delivery system 1802. The delivery system 1802 may include one or more fibers. In some embodiments, the illumination module 102 launches light into a surface of the waveguide 112 proximate an output area 1806. After the light reflects from the end reflector 114 and the polarization-sensitive reflector 116, at least a portion of the light is reflected toward the SLM 106. The light may transmit through the SLM 106 to the output area 1806. The SLM 106 may be located on a side of the illumination system 1800 proximate the output area 1806. In some implementations, the illumination module 102 may include one or more coherent light sources, such as lasers, and output coherent light. In other implementations, the lighting module 102 may include one or more incoherent light sources, such as LEDs (eg, superluminescent diodes, organic light emitting diodes (OLEDs)), and output incoherent light.

[0196] The illumination system 1800 may be configured to operate in a reflective mode using incoherent light. In the reflective mode, the illumination module 102 injects light into the surface of the waveguide 112 opposite the end reflector 114. In some embodiments, the illumination module 102 injects light into the surface of the waveguide 112 opposite the output area 1806 and / or the refractive optical element 118. Light from the illumination module 102 may thus reflect from the end reflector 114 and then from the polarization-sensitive reflector 116. The SLM 106 may be positioned on a side of the illumination system 1800 proximate the first surface 113A at the base or bottom of the waveguide 112. As a result, at least some of the light is incident on the SLM 106. The SLM 106 may be a reflective SLM that modulates the reflected light. Such reflected light may propagate through the PBS 104, e.g., the waveguide 112 and the refractive optical element 118, to reach the output area 1804. The illumination module 102 may include one or more incoherent light emitters, such as, for example, light emitting diodes (LEDs) (e.g., superluminescent diodes, organic light emitting diodes (OLEDs)). In other implementations, the illumination module 102 comprises one or more coherent light sources, such as a laser and outputs coherent light.

[0197] 20A and 20B, the lighting module 102 may include a light pipe integrator 1030 configured to receive light from one or more light emitters and mix the light received by the one or more light emitters. The light emitters may include light emitters of one or more different colors. The size and / or number of the light emitters may vary for the different colors.

[0198] The size and / or number of light emitters may depend, for example, on the optical efficiency and / or white balance of the light emitters or possibly other factors. To counteract the reduced efficiency of a color emitter with relatively low efficiency, the number and / or size of the emitters of that particular color may be increased. Similarly, to compensate for a color emitter with relatively higher efficiency, the number and / or size of the emitters of that particular color may be decreased. Similarly, the number and / or size of the emitters of that particular color may be increased (or decreased) to increase (or decrease) the contribution of that color to the overall output, for example, to obtain a desired white balance.

[0199] In various implementations, having different numbers and / or sizes of emitters for different colors can result in regions or areas for emitters of different colors having different sizes. Figures 20A-20B, for example, show a light pipe with one or more different color regions produced by different sizes and / or numbers of light sources of different colors.

[0200] 20A shows an exemplary light pipe integrator 1030 having three such regions, namely, a first color source emission area 1032, a second color source emission area 1034, and a third color source emission area 1036, corresponding to the emission regions or active areas of emitters for three different colors. In this example, the first color source emission area 1032 is smaller than the second color source emission area 1034 and the third color source emission area 1036, and the second color source emission area 1034 is smaller than the third color source emission area 1036. The first color source emission area 1032, the second color source emission area 1034, and the third color source emission area 1036 may correspond to light of a first, second, and third color, respectively. The difference in areas may be used to counteract reduced efficiency of emitters for particular colors and / or to provide a desired distribution of color components, e.g., to produce a desired white balance. The third color source emission area 1036 may be larger than the first color source emission area 1032 and the second color source emission area 1034 because a larger number of emitters of the third color may be used than the first or second color. Alternatively, or in addition, the emitter or emitters outputting light of the third color may be larger than the emitter or emitters outputting light of the first or second color. Similarly, the second color source emission area 1034 may be larger than the first color source emission area 1032 because a larger number of emitters of the second color may be used than the first color. Alternatively, or in addition, the emitter or emitters outputting light of the second color may be larger than the emitter or emitters outputting light of the first color.

[0201] Other configurations are also possible. For example, even if the size of the emitters of one color is larger than the size of the emitters of another color, the number of emitters may be large enough to produce a larger emission area for one color as opposed to the other colors. Similarly, even if the number of emitters of one color is smaller than the number of emitters of another color, the size of the emitters may be large enough to produce a larger emission area for one color as opposed to the other colors. In some embodiments, multiple emitters are used for a particular color source emission area 1032, 1034, 1036. Alternatively, a single emitter may be used for a particular color source emission area 1032, 1034, 1036. The shape and arrangement of the color source emission areas 1032, 1034, 1036 may also vary with different embodiments. In some embodiments, the color source emission areas 1032, 1034, 1036 may be separated by other non-color sections 1042, 1044 that do not produce or transmit light emission. The shape and arrangement of the non-color sections 1042, 1044 may also vary with different embodiments. Also, in this example, three color source emission areas 1032, 1034, 1036 corresponding to three colors are shown, but the number and / or colors of the color source emission areas 1032, 1034, 1036 may vary. Similarly, in this example, two non-color sections 1042, 1044 are shown, but the number of non-color sections 1042, 1044 may vary. The colors may also vary. In one example, three colors, such as red, green, and blue, are used. The colors may differ. Additionally, which source emission areas 1032, 1034, 1036 correspond to which colors may also vary. Still other variations are possible.

[0202] In some implementations, the three color source emission areas 1032, 1034, 1036 may each be located on the same surface of the light pipe integrator 1030. Other configurations are also possible. The light pipe 1040 may receive light along an optical axis. The optical axis may be aligned with the length of the light pipe 1040. In some embodiments, the light pipe 1040 comprises a right-angle prism shape. Other shapes are also possible.

[0203] The size and shape, and therefore the dimensions, of the light pipe integrator 1030 may vary for different designs. The height of the light pipe integrator 1030 may be, for example, 0.20 mm to 2.5 cm. In some embodiments, the height may be, for example, 0.30 mm to 5.0 mm. In some embodiments, the height may be, for example, 0.50 mm to 2.0 mm. In some embodiments, the height is 0.70 mm. The width of the light pipe integrator 1030 may be, for example, 0.30 mm to 3.0 cm. In some embodiments, the width is 0.50 mm to 7.0 mm. In some embodiments, the width may be 0.85 mm to 3.0 mm. In some embodiments, the width is 1.20 mm. The length of the light pipe integrator 1030 may be, for example, 1.0 mm to 5.0 cm. In some embodiments, the length is 2.0 mm to 1.5 cm. In some embodiments, the length may be 3.0 mm to 9.0 mm. In some embodiments, the length is 4.50 mm. Other ranges formed by any of these values ​​are also possible. Values ​​outside these ranges are also possible.

[0204] The various color-emitting areas 1032, 1034, 1036 may be separated by parallel (e.g., perpendicular) non-color sections 1042, 1044, respectively. For example, as shown in FIG. 20A , the first color-emitting area 1032 and the second color-emitting area 1034 may be separated by the first non-color section 1042, and the second color-emitting area 1034 and the third color-emitting area 1036 may be separated by the second non-color section 1044. The distance between the first color-emitting area 1032 and the second color-emitting area 1034 may be, for example, 0.01 mm to 0.50 mm. In some embodiments, the distance is 0.11 mm. The distance between the second color-emitting area 1034 and the third color-emitting area 1036 may be 0.01 mm to 0.50 mm. In some embodiments, the distance is 0.11 mm. Other ranges formed by any of these values ​​are also possible. Values ​​outside these ranges are also possible.

[0205] The first color source emitting area 1032 may be located at the edge of the first surface of the light pipe integrator 1030. In some embodiments, the first color source emitting area 1032 spans the entire dimension (e.g., height) of the first surface of the light pipe integrator 1030, as shown in FIG. 20A. The first color source emitting area 1032 may have a length of, for example, 0.2 mm to 1.2 mm. In some embodiments, the length is 0.70 mm. In some embodiments, the length is 0.59 mm. The first color source emitting area 1032 may have a width of, for example, 0.01 mm to 0.50 mm. In some embodiments, the width is 0.12 mm. In some embodiments, the width is 0.14 mm. Other ranges formed by any of these values ​​are also possible. Values ​​outside these ranges are also possible.

[0206] In some designs, the second color source emitting area 1034 may be disposed between the first color source emitting area 1032 and the third color source emitting area 1036. The second color source emitting area 1034 may span the entire dimension (e.g., height) of the first surface of the light pipe integrator 1030, as shown in FIG. 20A. The second color source emitting area 1034 may have a length between 0.2 mm and 1.2 mm. In some embodiments, the length is 0.70 mm. In some embodiments, the length is 0.59 mm. The second color source emitting area 1034 may have a width between 0.01 mm and 0.90 mm. In some embodiments, the width is 0.37 mm. In some embodiments, the width is 0.45 mm. Other ranges formed by any of these values ​​are also possible. Values ​​outside these ranges are also possible.

[0207] The third color source emitting area 1036 may be located at the edge of the first surface of the light pipe integrator 1030. In some embodiments, the third color source emitting area 1036 spans the entire dimension (e.g., height) of the first surface of the light pipe integrator 1030, as shown in FIG. 20A. The third color source emitting area 1036 may have a length between 0.2 mm and 1.2 mm. In some embodiments, the length is 0.70 mm. The third color source emitting area 1036 may have a width between 0.01 mm and 1.50 mm. In some embodiments, the width is 0.49 mm. In some embodiments, the width is 0.50 mm. Other ranges formed by any of these values ​​are also possible. Values ​​outside these ranges are also possible.

[0208] As noted above, the number, size, shape, orientation, separation distance, and other attributes of the color source emission areas 1032, 1034, 1036 may vary for different designs and may be determined based on one or more factors. For example, these attributes may be based on the efficiency of the light source (e.g., LED) and / or the white balance of the light pipe integrator 1030. The layout of the light sources may vary. The shape of one or more of the color source emission areas 1032, 1034, 1036 may be rectangular, although other shapes are possible.

[0209] The light pipe integrator 1030 may take one of several forms. For example, the light pipe 1040 may be hollow in some embodiments. In such embodiments, the interior walls of the light pipe 1040 may be reflective (e.g., include a mirror coating). In some embodiments, such reflective coatings may facilitate improved mixing of light as it propagates along the optical axis of the light pipe integrator 1030. In some embodiments, the light pipe 1040 may include a solid material such as an optically transmissive material (e.g., plastic, glass, resin). Light may be configured to propagate through the light pipe integrator 1030 and reflect off the sidewalls by total internal reflection (TIR). In some embodiments, the optically transmissive material within the light pipe integrator 1030 through which the light propagates is diffusive. The diffusive material may be configured to scatter light propagating within the light pipe integrator 1030 (e.g., scatter light forward along the length of the light pipe integrator 1030), thereby mixing light of different colors. In some embodiments, the light pipe 1040 may include scattering features, such as small particles, to help diffuse the light. For example, the light pipe 1040 may be a volume light integrator doped with diffusing particles.

[0210] FIG. 20B shows an exemplary light pipe integrator 1030 using an alternative arrangement of color source emission areas 1032, 1034, according to some embodiments. As shown in FIG. 20B, more than one color source emission area 1032, 1034, 1036 may be disposed along the edge of the first surface of the light pipe integrator 1030. The first color source emission area 1032 and the second color source emission area 1034 may be separated from each other by a portion of an integrated non-color section 1046. One or both of the first color source emission area 1032 and / or the second color source emission area 1034 may be separated from the third color source area 1036 by the integrated non-color section 1046. In some embodiments, the integrated non-color section 1046 is shaped like a capital T, although other shapes are possible. The second color source emission area 1034 and the first color source emission area 1032 may be disposed relative to each other along a first axis. The third color source emitting area 1036 may be disposed along a second axis different from the first axis relative to one or both of the second color source emitting area 1034 and / or the first color source emitting area 1032. In some designs, the first axis may be perpendicular to the second axis, as shown in Figure 20B. However, as discussed above, a wide range of different shapes, sizes, arrangements, and configurations are also possible.

[0211] 20C-D show additional aspects of embodiments of color emitters that may be used within the lighting module 102. The lighting module 102 may produce colored light using one or more color emitters (e.g., laser diodes or light-emitting diodes), and in some implementations, a white light source 1110 and a color modulator may be employed. The white light source 1110 may include, for example, one or more white light-emitting diodes (LEDs). The color modulator may include a spatial light modulator (SLM) 1122 having different pixels with associated color filters. The SLM 1122 may include, for example, a liquid crystal cell including one or more pixels that can be switched between states. The pixels may include, or be positioned relative to, a color filter, for example, such that light passing through a color pixel also passes through the color filter. For example, one or more pixels may have one or more color filters associated with it of a first color (e.g., red), one or more pixels may have one or more color filters associated with it of a second color (e.g., green), and one or more pixels may have one or more color filters associated with it of a third color (e.g., blue). The states of the pixels can be altered, for example, by applying an electrical signal. For example, the polarization state of light passing through the SLM 1122 may or may not be rotated depending on the state of the pixel. First and second polarizers 1116, 1118 may be included on either side of the SLM 1122. The polarizers 1116, 1118 may be crossed. Thus, the first polarizer 1116 may polarize light, for example, to a first linear polarization, and the second polarizer 1118 may block light of the first polarization. The liquid crystal cells of the SLM 1122 may rotate the polarization of light passing through the pixels, which may be switched to rotate the polarization of the light depending on the state of the pixel. Color filters associated with the pixels may be configured to pass light of certain colors. Thus, depending on which pixels are set to transmit light and which pixels are set to block light, the amount of light of different colors output by the lighting module 102 can be controlled.

[0212] The size, shape, and arrangement of the pixels and color filters may be varied to produce different regions corresponding to different colors. Figure 20D shows two example arrangements of different regions 1112 corresponding to different colors. The example in Figure 20D shows regions having one of three colors (e.g., red, green, and blue). However, the number of colors may vary. Similarly, the number, size, and shape of the regions may also vary for different designs.

[0213] Thus, the color modulator may be controlled to activate or deactivate different regions to produce desired colors and / or color combinations. Additionally, the color modulator may be controlled to vary the amount of light output by a pixel to provide more than just two levels of brightness for that pixel. For example, instead of simply controlling whether that pixel is on or off, additional intermediate levels for the pixel may be selected (e.g., by rotating the polarization by different amounts), thereby allowing more than two different amounts of light output to be output from that pixel. In some implementations, the color pixels may be addressed sequentially in time. For example, a pixel corresponding to a first color may be addressed in a first time period, a pixel corresponding to a second color may be addressed in a second time period, and so on. Different colors may be produced at different times, and the color output may be varied in a time-sequential manner, e.g., coordinated with another SLM 106 illuminated with light from the illumination module 102 and producing different color images at different times.

[0214] The size and / or number of pixels associated with a given color can be selected to provide a desired color balance (e.g., white balance) and / or to account for different efficiencies associated with different colors, as described above with respect to Figures 20A and 20B. Thus, the areas (and associated brightness levels) associated with different color pixels that are activated may be used to control the amount of light of a particular color output from the lighting module 102. Similarly, the discussion with respect to Figures 20A and 20B also applies to the various configurations of lighting module 102 discussed with respect to Figures 21A-21C. For example, a lighting module 102 including a white light source 1110 and a color modulator as shown with respect to Figures 20A and / or 20B can be used in conjunction with a light pipe integrator 1030.

[0215] 21A-21C illustrate a dichroic combiner 1052 in series with a light integrator 1054 configuration of a light pipe integrator 1030 of an illumination module 102, according to some embodiments. The dichroic combiner 1052 may alternatively be referred to as a dichroic light combiner 1052. FIG. 21A shows an integrated structure having a first region for the dichroic combiner 1052 and a second region for the light integrator 1054. In some embodiments, the dichroic combiner 1052 may be positioned adjacent to the light integrator 1054. In the example shown, the light pipe integrator 1030 is linear and elongated, with a first region for the dichroic combiner 1052 at a first end and a second region for the light integrator 1054 at a second end. This elongated integrated structure may comprise a rod. This elongated integrated structure may have a planar outer surface and, in some implementations, may have the shape of a right-angle prism. Light emitters 1002a, 1002b, and 1002c may be butt-coupled to one or more of these outer surfaces and couple light into the light pipe integrator 1030. In some embodiments, the dichroic combiner 1052 may be seamlessly formed with or integrated into the light integrator 1054. In some embodiments, for example, one or both of the first and second regions includes a hollow portion defined by an inner reflective sidewall through which light may propagate. As described above, the inner reflective sidewall may be coated with a reflective coating. In some embodiments, one or both of the first and second regions includes a solid, optically transmissive material (e.g., plastic or glass) through which light may propagate from the sidewall via total internal reflection. In some designs, a combination of such solid and hollow portions may be included. The dichroic combiner 1052 may be attached to the optical integrator 1054, but in some embodiments they are fabricated as an integrated (e.g., monolithic) element. In some embodiments, the first region and / or the second region are fabricated by combining or attaching different portions.

[0216] FIG. 21B shows an implementation of the embodiment of FIG. 21A with light emitters 1002a, 1002b, 1002c and dichroic combining elements 1022, 1024 of a dichroic combiner 1050. The dichroic combining elements 1022, 1024 may be reflective optical elements. The dichroic combining elements 1022, 1024 may be optically transmissive and / or optically reflective. For example, the dichroic combining elements 1022, 1024 may each be tuned to a particular wavelength or range of wavelengths so as to reflect light from that wavelength or range of wavelengths and transmit light of other wavelengths. For example, the dichroic combining elements 1022, 1024 may include a dichroic coating. In some embodiments, the dichroic combining elements 1022, 1024 include angled surfaces that direct light from the emitters 1002a, 1002b, 1002c along a common optical path. Color mixing elements, including the dichroic combining elements 1022, 1024, are arranged along this optical path. In some embodiments, the angled input surfaces are angled relative to this optical path. Thus, one or more of the dichroic combining elements 1022, 1024 may be positioned at an angle θ relative to this optical path and / or relative to the surface of the light pipe integrator 1030. The angle θ may be, for example, 20°. o ~45 o In some designs, the angle may be 30 o The selected angle θ may increase or optimize the efficiency and / or intensity of the light mixing.

[0217] FIG. 21C shows an exemplary embodiment of the integrated structure of FIG. 21A with a dichroic combining element 1022 and a light integrator 1054 of a dichroic combiner 1052. The dichroic combining element 1022 is positioned relative to the first and second light emitters 1002a, 1002b to receive and reflect different colored light from the first and second light emitters 1002a, 1002b, respectively. The dichroic combining element 1022 may be configured to transmit only certain wavelengths of light (e.g., red light) and reflect other wavelengths of light (e.g., blue and green). For example, the dichroic combining element 1022 may be configured to transmit light emitted by a third light emitter 1002c and reflect light from the first and second emitters 1002a, 1002b. The dichroic combining element 1022 may be tilted more (the angle θ shown is reduced) to accommodate reflections from two emitters 1002a, 1002b compared to a design in which the dichroic combining element 1022 reflects light from a single color emitter, although such a configuration may be simpler to fabricate due to the reduced number of dichroic combining elements 1022 involved and potentially components to be assembled.

[0218] By using this technique of reducing the number of dichroic combining elements 1022 employed, a single dichroic combining element 1022 for receiving, reflecting, and / or transmitting light from multiple different color emitters may be applied to any of the other design concepts discussed herein. Thus, instead of using two dichroic beam combiners, a single dichroic beam combiner may be used to receive, reflect, and / or transmit light from multiple different color emitters. This single dichroic beam combiner can receive light from a third color emitter, having a third different color transmitted through the dichroic beam combiner. The combination of two dichroic beam combining elements or dichroic beam combiners into a single dichroic beam combiner may be utilized for the different design approaches described herein and may provide simplified manufacturing. Likewise, any property or characteristic discussed herein may be applied to structures and concepts discussed anywhere in this specification. Likewise, any property, characteristic, or concept discussed anywhere in this specification may be applied to other structures, characteristics, or concepts described herein.

[0219] The light integrator 1054 may include a solid, optically transmissive material (e.g., plastic or glass) that includes diffusing features, such as particles or other scattering features, to more effectively mix the colors of the light, as shown in FIG. 21C . Thus, the light integrator 1054 may be configured to diffusely scatter light as it propagates along the optical axis of the light pipe integrator 1030. For example, the light pipe integrator 1030 may include a diffusing material, such as a translucent material and / or a material including microparticles configured to scatter light. Other approaches to diffusing and / or scattering light may also be employed. For example, the walls of the light integrator 1054 may be textured to scatter light. Also, in designs in which the light pipe integrator 1030 is hollow, the inner sidewalls from which light reflects may be textured or coated to increase diffuse reflection. The inner sidewalls may be colored, for example, white. Light mixing (e.g., color mixing) within the light pipe integrator 1030 is thereby increased.

[0220] Adding a light pipe integrator 1030, whether within an integrated structure or not, and / or adding diffusing features to the optically transmissive material, for example, which may potentially increase mixing, may be utilized for different design approaches described herein. Similarly, any property or feature discussed herein can be applied to the structures and concepts discussed anywhere herein. Similarly, any property, feature, or concept discussed anywhere herein can also be applied to other structures, features, or concepts described herein.

[0221] It may be advantageous to include a reflective lighting module configured to enter on a first side and exit on a second (e.g., opposite) side where light is displaced to reflect from the first and second opposite sides between entry and exit. Such a configuration may increase color mixing. FIGS. 22A-22C illustrate a reflective lighting module 1060 according to some embodiments. FIG. 22A shows a side view of the reflective lighting module 1060. FIG. 22B shows an isometric view of the reflective lighting module 1060 of FIG. 22A. The reflective lighting module 1060 may include one or more light sources 1064, one or more openings for receiving light from the one or more light sources 1064, an elongated lighting module body 1062 having ends and sidewalls between the two ends, and an exit opening 1066. The light sources 1064 may be disposed on locations on the sidewalls of the lighting module body 1062. The exit opening 1066 may be located at another location on the side wall of the lighting module body 1062. The locations on the side wall at which the light source 1064 and the exit opening 1066 are positioned may be on opposite sides of the lighting module body 1062, as illustrated in FIGS. 22A and 22B . However, the locations on the side wall at which the light source 1064 and the exit opening 1066 are positioned may, in some implementations, be on the same side of the lighting module body 1062 or at other locations on the side wall. In some embodiments, such as shown in FIGS. 22A and 22B , the light source 1064 and the exit opening 1066 are located at opposite ends of the lighting module body 1062. The shape of the lighting module body 1062 may be rectangular (e.g., a right-angle prism), although other shapes are possible. In some embodiments, the lighting module body 1062 is elongated, with the distance between the ends exceeding the width between the opposite walls. In some embodiments, the aspect ratio of the lighting module body 1062 (e.g., the ratio of the distance between the ends to the distance between the opposite walls) is at least greater than 2, or 3, or 4, or 5, or any value in any range between any of these values. Other aspect ratios are also possible.

[0222] The lighting module body 1062 may be hollow and include an interior region or cavity through which light propagates from one or more light sources 1064 to the output aperture 1066 and reflects one or more times or more than one time from interior portions of the sidewalls. The interior portions of the sidewalls may be coated to increase reflectivity. The interior portions of the sidewalls can be white to increase reflectivity. Increasing reflectivity can potentially improve the efficiency of light output through the aperture 1066. Multiple reflections can also increase mixing (e.g., color mixing). In some implementations, the reflections may diffuse the reflections, further increasing mixing. Thus, the interior portions of the sidewalls may be coated and / or textured to provide diffuse reflection and possibly scattering.

[0223] The lighting module body 1062 may have an interior region that is solid (as opposed to hollow) and, in some designs, may comprise a substantially transparent material (e.g., glass or plastic). For example, the lighting module body 1062 may comprise a transmissive medium (e.g., plastic, glass, acrylic, etc.). Such a lighting module body 1062 may be referred to as a volumetric light integrator. Light propagates within the interior region from the one or more light sources 1064 to the output aperture 1066 and may reflect off interior portions of the sidewalls one or more times, or two or more times. Such reflections may be the result of total internal reflection. However, alternatively or in addition, one or more surfaces of the lighting module body 1062 may be coated with a reflective or mirror coating. For example, the surfaces of the lighting module body 1062 may be coated with a white and / or reflective or mirror coating to promote reflection. As discussed above, increasing reflectivity may improve the efficiency of light output through the output aperture 1066.

[0224] The lighting module body 1062 may include a diffusing material (such as that described with respect to the light pipe integrator 1030 in FIG. 22C). In some embodiments, the diffusing material may be doped with diffusing particles or include some other diffusing and / or scattering characteristics. Increased diffusion or scattering can increase mixing, such as color mixing.

[0225] The light source 1064 may include one or more LEDs in some implementations, although other types of light sources (e.g., lasers) may also potentially be used. For example, the light sources 1064 may each be configured to emit light of a distinct color (e.g., red, green, blue). The output aperture 1066 includes an opening through which light may propagate from within the lighting module body 1062. A polarization-sensitive element may be included, for example, proximate the output aperture 1066. The polarization-sensitive element may be polarization-selective. For example, the polarization-selective element may reflect light of one polarization state and transmit light of another polarization state. The polarization-sensitive or polarization-selective element may include, for example, a polarizer, such as a wire-grid polarizer. The polarization-sensitive element may be configured to recycle light within the lighting module body 1062 to further improve the efficiency of the system. For example, if light output of a particular polarization state is desired, the polarization sensitive element may transmit light having such polarization, but may reflect light having a different polarization. This reflected light will be returned to the lighting module body 1062, retained therein, reflect therein, possibly altering its polarization, and exit through the light sensitive element (if the light has the appropriate polarization).

[0226] The reflected illumination module 1060 may be configured to be positioned adjacent to a polarizing beam splitter (e.g., the PBS 104). Such a polarizing beam splitter may be configured for a particular polarization (e.g., the PBS 104 may redirect light of a particular polarization to the SLM 106). The illumination module body 1062 may be configured to output light of that polarization. For example, a polarization-sensitive element may transmit light of that particular polarization that the PBS 104 is configured to redirect to the SLM 106 and reflect other polarizations.

[0227] FIG. 22C illustrates an exemplary reflective lighting module 1060 that additionally includes an extension 1072. The extension 1072 can be advantageous in directing light output and / or increasing mixing (e.g., color mixing). The extension 1072 may be positioned between the reflective lighting module 1060 (e.g., along the opening 1066) and the PBS 104 (not shown). The extension 1072 may be positioned adjacent to the reflective lighting module 1060 (e.g., along the output opening 1066). The extension 1072 may have properties, characteristics, and / or properties similar to the light integrators described elsewhere herein. Thus, the extension 1072 may be hollow or solid (e.g., plastic, glass, acrylic, etc.). The interior or exterior of the extension 1072 may be coated with a reflective (e.g., white, mirror) coating, possibly increasing efficiency. The extension 1072 may be a right-angle prism. The extension 1072 may, in some implementations, be elongated and have a length greater than its width or height. Other shapes are possible. The extension 1072 may be configured to be positioned adjacent to a polarizing beam splitter (e.g., the polarizing beam splitter 104 described above).

[0228] The various implementations described above may be included within one or more separate color light emitters 1002a, 1002b, 1002c. While different color light emitters 1002a, 1002b, 1002c may be useful for certain designs, white light emitters, such as white LEDs, may be configured to provide different color illumination. As illustrated in FIGS. 23A-23E, a white light source may be combined with a switchable color filter to provide a color light source, for example. Such a light source may include a variable color light source whose color output can be varied and / or selected. In particular, the switchable color filter has an electrical input that can be varied to control the color light output. Such a light source may be included within the lighting module 102 discussed herein.

[0229] 23A-23E illustrate a cholesteric liquid crystal (CLC) as a switchable color filter, according to some embodiments. FIG. 23A shows a broadband light source 1082, such as an LED (e.g., a white light LED). In some embodiments, the broadband light source 1082 used outputs broadband visible light. Such light can span a spectrum sufficiently to include, for example, blue and red, and various designs may have a broader spectral output. In some embodiments, a white light source that emits visible white light may be used. The broadband light source 1082 may output wavelengths that extend continuously over a range or may include multiple peaks in wavelength that may be separated from each other by spectral regions of reduced, and possibly even negligible, intensity. The broadband light source 1082 may be positioned relative to the switchable color filter 1088 such that it is in the path of the light output by the broadband light source 1082 so that the switchable color filter 1088 receives light therefrom. The color filter 1088 may include one or more wavelength-selective filters 1088a, 1088b, 1088c. The switchable color filter 1088 is in front of the broadband light source 1082, although other configurations are possible, for example, optical systems such as mirrors, prisms, light pipes, or other components direct light from the broadband light source 1082 to the switchable color filter 1088. As discussed above, the switchable color filter 1088 can filter light incident thereon, and the spectral output is controlled by control signals to the switchable color filter 1088. As an example, the switchable color filter 1088 may include a CLC cell. The CLC cell may be in electrical communication with a voltage source 1086, which can provide a control signal to the CLC cell to modify the spectral transfer function of the CLC cell. The CLC cells may include distinct color CLC cells, which may include, for example, a first color CLC cell (e.g., blue) 1088a, a second color CLC cell (e.g., green) 1088b, and / or a third color CLC cell (e.g., red) 1088c. The distinct color CLC cells can be activated separately. When activated, the color CLC cells may block transmission of specific spectral regions.For example, the first color CLC cell 1088a may be controlled to block wavelengths corresponding to a first color (e.g., blue), as illustrated in FIG. 23B. For example, when in the off state, the first CLC cell 1088a may block wavelengths corresponding to blue light. The second color CLC cell 1088b may be controlled to block wavelengths corresponding to a second color (e.g., green), as illustrated in FIG. 23C. For example, when in the off state, the second CLC cell 1088b may block wavelengths corresponding to green light. The third color CLC cell 1088c may be controlled to block wavelengths corresponding to a third color (e.g., red), as illustrated in FIG. 23D. For example, when in the off state, the third CLC cell 1088c may block wavelengths corresponding to red light. When the first, second, and third color CLC cells 1088a, 1088b, and 1088c, respectively, are in the on state, the first, second, and third CLC cells 1088a, 1088b, and 1088c no longer block the wavelengths that they previously blocked (blue, green, and red, respectively). Thus, broadband illumination appears to be transmitted when a control signal is applied. Other configurations are possible. Thus, the first CLC cell 1088a may be turned on, and the second CLC cell 1088b and the third CLC cell 1088c may be turned off, producing (e.g., transmitting) a first color (e.g., blue) from the broadband light source. Thus, the second CLC cell 1088b may be turned on, the first CLC cell 1088a and the third CLC cell 1088c may be turned off, and a second color (e.g., green) may be produced (e.g., transmitted) from the broadband light source. Thus, the third CLC cell 1088c may be turned on, the first CLC cell 1088a and the second CLC cell 1088b may be turned off, and a third color (e.g., red) may be produced (e.g., transmitted) from the broadband light source. The first, second, and third CLC cells 1088a, 1088b, 1088c may thus be turned on sequentially in time. For each frame of a particular color, only one of the color CLC cells is turned on to pass only one of the colors over the period in which the frame is to be presented. Other configurations are also possible.For example, different, fewer, or more colors may be employed. The electrical signals used to alter the state of the color CLC cells may be varied.

[0230] Other configurations are also possible. As described above, for example, three different colored light emitters 1002a, 1002b, and 1002c may be used. FIG. 24 illustrates another perspective view of a lighting system, for example, according to some embodiments. As shown, the lighting system 1000 may include three lighting modules 102. As shown, the lighting modules 102 may each be configured to abut the waveguide 112. The lighting modules 102 may each be disposed along a common surface of the waveguide 112. In some embodiments, the lighting modules 102 may each be configured to emit light of a different color. In some embodiments, the lighting modules 102 are each configured to emit a different color (e.g., red, blue, and green, respectively). The lighting modules 102 can be oriented to emit light parallel to each other and / or parallel to the surface of the waveguide 112. The lighting modules 102 may be configured to be time-multiplexed. For example, the lighting modules 102 may each be configured to emit light sequentially. 25 illustrates a perspective view of another example lighting system 1000, according to some embodiments. As shown, the lighting system 1000 may include two lighting modules 102.

[0231] Upon perusal of this disclosure, those skilled in the art will appreciate further and additional alternative structural and functional designs for systems and processes for motion-based content navigation through the principles disclosed herein. Thus, while particular embodiments and applications have been illustrated and described, it should be understood that the disclosed embodiments are not limited to the precise structure and components disclosed herein. Various modifications, changes, and variations, which will be apparent to those skilled in the art, can be made in the arrangement, operation, and details of the methods and apparatus disclosed herein without departing from the spirit and scope, as defined in the appended claims. Polarization modulation

[0232] As discussed above with reference to FIG. 6, light injected into the waveguides 270, 280, 290, 300, 310 may be provided by an optical module 540 and directed to the spatial light modulator 530 via a beam splitter 550. In various implementations, the spatial light modulator 530 may be configured to modulate the polarization state of the light. In such embodiments, the spatial light modulator 530 can be illuminated by an illumination system in which light from the optical module 540 is directed towards the light modulator 530 via a polarizing beam splitter 1306, as shown in FIG.

[0233] The illumination system depicted in FIG. 26 is configured to provide illumination to an embodiment of a spatial light modulator 106 configured to modulate the polarization state of the light. In the illustrated implementation, light from the light source 102 can be internally coupled into a polarizing beam splitter (PBS) 1306 via internal coupling optics 1304. The PBS 1306 is configured to direct light having a first polarization state (e.g., an s-polarization state) from the light source 102 toward the spatial light modulator 106 and transmit light modulated by the spatial light modulator 106, which may have a second polarization state (e.g., a p-polarization state), toward a viewer. In various embodiments, the modulated light can be conditioned by projection optics 1302, which is positioned between the PBS 1306 and the viewer. The size of the PBS 1306 is determined by various factors, including, but not limited to, the spatial extent of the spatial light modulator 106. For example, consider the implementation illustrated in FIG. 26 in which light from the light source 102 is emitted generally along a horizontal axis parallel to the x-axis. In such implementations where light is directed toward an embodiment of the spatial light modulator 106 along a direction normal to the surface of the spatial light modulator 106 (e.g., along a vertical axis parallel to the y-axis), the reflective surface should be tilted at a 45-degree angle with respect to the horizontal axis. To uniformly illuminate the spatial light modulator along its length, the length of the PBS 1306 is at least equal to the length of the spatial light modulator 106. Because the reflective surface of the PBS 1306 is tilted at a 45-degree angle, the height of the PBS 1306 is also at least equal to the length of the spatial light modulator 106. For example, if the length of an embodiment of the spatial light modulator 1306 is approximately 10 mm, the PBS 1306 is a cube having a length and height at least equal to 10 mm. In other embodiments of the illumination system, the PBS 1306 can have dimensions (e.g., length, width, height, or radius) greater than or equal to approximately 10 mm. Additionally, in some embodiments, the light source 102 may need to be spaced a distance from the PBS 1306. These and other factors may lead to an increase in the size of the illumination system. It may be desirable to reduce the weight, volume, and / or spatial extent of the illumination system that provides illumination to the spatial light modulator 106.For example, when the spatial light modulator 106 is associated with the implementation of the wearable display system discussed herein, it may be desirable to reduce the size of the illumination system. However, it may not be practical to reduce the height of a conventional PBS 1306 and simultaneously redirect light uniformly across the entire length of the spatial light modulator 106 along a direction normal to the surface of the spatial light modulator. Various embodiments described herein include a PBS having a surface that is tilted with respect to a horizontal axis by an angle of less than about 45 degrees, reducing the height of the PBS and employing multiple turning features to provide the additional turning functionality required to uniformly illuminate the spatial light modulator along the normal direction.

[0234] 27 schematically illustrates an embodiment of an illumination system 1000 configured to illuminate a spatial light modulator 106, which modulates the polarization of incident light. The illumination system 1000 includes a polarizing beam splitter (PBS) 1306 configured to direct light having a first polarization state (e.g., an s-polarization state) from the light source 102 toward the spatial light modulator 106 and transmit light modulated by the spatial light modulator 106, which may have a second polarization state (e.g., a p-polarization state), toward a viewer. As discussed above, the spatial light modulator 106 can extend along a horizontal axis parallel to the x-axis. The optical axis light source 102 can be aligned parallel to the x-axis, and light from the source 102 can be emitted in a cone having a half-angle of less than approximately 60 degrees relative to the optical axis of the light source 102. The PBS 1306 can be configured to be compact and have a reduced weight, volume, and / or spatial extent compared to the PBS 1306 depicted in FIG. 26 . For example, the PBS 1306 can be configured to have a dimension (e.g., length, width, height, or radius) of less than or equal to about 5 mm. As another example, the PBS 1306 can be configured to have a dimension (e.g., length, width, height, or radius) of less than about 10 mm. As yet another example, the PBS 1306 can be configured to have a dimension (e.g., length, width, height, or radius) of about 2.0 mm to about 6.0 mm, about 3.0 mm to about 5.0 mm, about 3.5 mm to about 4.5 mm, or any value within these ranges / subranges or any range formed by any of these values.

[0235] Various embodiments of the PBS 1306 include a light-redirecting optical element or waveguide 112 including a first surface 113A disposed over the spatial light modulator 106 and a second surface 113B opposite the first surface 113A. In the implementation depicted in FIG. 27 , in which the illumination system 1000 is configured as a front light, the light-redirecting optical element 112 can be disposed at the bottom of the PBS 1306 such that the first surface 113A forms the bottom surface of the PBS 1306. The waveguide 112 further includes a light input surface 113C between the first and second surfaces 113A and 113B. The light input surface 113C is configured to receive light from the light source 102. The waveguide 112 further includes an end reflector 114 disposed on the side opposite the light input surface 113C. The end reflector 114 is configured to reflect light coupled into the waveguide 112 through the light input surface 113C. A portion of the light coupled into the waveguide 112 through the light input surface 113C propagates directly to the end reflector 114 without being reflected from any other surface, such as the first surface 113A or the second surface 113B. This light is reflected by the end reflector 114 on the second surface 113B, as discussed below. A portion of the light coupled into the waveguide 112 can be reflected from the first surface 113A by the process of total internal reflection (TIR) ​​before being reflected by the end reflector 114.

[0236] In various designs, one or more turning features 1314 are disposed across the second surface 113B. The turning features 1314 may be configured to redirect light reflected from the end reflector 114 toward the spatial light modulator 106. The turning features 1314 may also be configured to transmit light reflected from the spatial light modulator 106 through the waveguide 112. The PBS 1306 further includes a refractive optical element 118 configured to compensate for any refractive optical effects introduced by the waveguide 112. The PBS 1306 may further include a clean-up polarizer 1310. The clean-up polarizer 1310 may be configured to transmit light having a second polarization state (e.g., a p-polarization state) and block light having a first polarization state (e.g., an s-polarization state). In this manner, the clean-up polarizer 1310 can remove unmodulated light unintentionally transmitted through the waveguide 112.

[0237] The waveguide 112 may comprise a transmissive material (e.g., plastic, glass, acrylic, etc.). The refractive optical element 118 may also comprise a transmissive material (e.g., plastic, glass, acrylic, etc.). The turning feature 1314 may be formed on the second surface 113B of the waveguide 112, for example, by a process such as molding. The plurality of turning features 109 may include microstructures or nanostructures.

[0238] In various embodiments, the turning feature 1314 may include a groove formed by a pair of facets (e.g., first and second facets 1326 and 1328, respectively). The groove may be straight or curved (e.g., extending along a straight line or a curved line). The facets may be planar in some embodiments. In other embodiments, such as those discussed below with reference to Figures 29A and 29B, the facets may be curved to provide optical power. In some embodiments, the facets may be of equal width. In some other embodiments, the facets may have unequal widths. The facets may include an angle β between them. The angular separation β between the facets may vary from about 15 degrees to about 120 degrees. Different facets of the turning feature 1314 may be angled by different amounts (e.g., with respect to a horizontal axis parallel to the x-axis). The pitch (e.g., the distance between a pair of consecutive first facets 1326 on two consecutive turning features 1314 or a pair of consecutive second facets 1328 on two consecutive turning features) can be from about 20 μm to about 200 μm. For example, the pitch can be greater than or equal to about 20 μm and less than or equal to about 200 μm, greater than or equal to about 30 μm and less than or equal to about 175 μm, greater than or equal to about 40 μm and less than or equal to about 150 μm, greater than or equal to about 50 μm and less than or equal to about 125 μm, greater than or equal to about 60 μm and less than or equal to about 100 μm, greater than or equal to about 70 μm and less than or equal to about 90 μm, greater than or equal to about 75 μm and less than or equal to about 85 μm, or a value within these ranges / subranges or any range formed by any of these values. The portion of the second surface 113B that extends beyond the extent of the spatial light modulator 106 (e.g., along the x-axis) can be devoid of turning features 1314.Without being bound by any particular theory, the pitch of the plurality of redirecting features 1314 can be configured to avoid dead pixels in the spatial light modulator 106 and / or to avoid optical effects that may result from non-uniform illumination across the spatial light modulator 106.

[0239] In various embodiments, the first surface 113A of the waveguide 112 can be planar and generally parallel to the surface of the spatial light modulator 106, which may extend along an axis parallel to the x-axis, while the second surface 113B of the waveguide 112 can be tilted or slanted with respect to the first surface 113A, a horizontal axis parallel to the x-axis, and / or the spatial light modulator or the front surface of the modulator, such that the waveguide 112 is wedge-shaped. The second surface 113B can be tilted or slanted toward the light input surface 113C. The tilt angle α of the second surface 113B with respect to the horizontal axis parallel to the first surface 113A can have a value in the range of about 15 degrees to about 45 degrees. For example, the inclination angle α of the second surface 113B relative to a horizontal axis parallel to the first surface 113A can be any value within the range of about 20 degrees to about 35 degrees, about 24 degrees to about 30 degrees, or within a sub-range within any range formed by any of these ranges / values.

[0240] In implementations of the wedge-shaped waveguide 112, the distance between the first surface 113A and the second surface 113B near the light input surface 113C (also referred to as the height of the light input surface 113C) may be smaller than the distance between the first surface 113A and the second surface 113B farther away from the light input surface 113C or near the end reflector 114. In various embodiments, the area of ​​the light input surface 113C may be less than the area of ​​the side of the wedge-shaped waveguide opposite the light input surface 113C. In some implementations, the tilt angle and the height of the light input surface 113C can be configured to receive substantially all of the light emitted within a light cone output from the light source 102. For example, if the source 102 includes an LED, the light from the LED is emitted within a light cone having a half angle of approximately 41 degrees relative to the optical axis of the LED (which may be aligned parallel to the x-axis). In such embodiments, the tilt angle of second surface 113B can be about 20 degrees to about 30 degrees relative to a horizontal axis parallel to the x-axis or relative to first surface 113A or spatial light modulator 106 or its front face, so that substantially all light output from light source 102, including an LED, is coupled into waveguide 112. The tilt angle of second surface 113B and / or the height of light input surface 113C can be reduced if light source 102 has low divergence. For example, if light source 102 is coupled to input surface 113C via an optical fiber, the tilt angle of second surface 113B can be less than 20 degrees.

[0241] The end reflector 114 is configured to reflect light incident from the light source 102 such that the reflected light is redirected by the turning feature 1314 along a direction approximately parallel to the normal to the surface of the spatial light modulator 106 (e.g., parallel to the y-axis). For example, the end reflector 114 and turning feature 1314 can be configured to redirect light from the source 102 toward the spatial light modulator 106 within a cone of approximately ±10 degrees relative to the normal to the surface of the spatial light modulator 106. The end reflector 114 can include a plastic or glass material coated with a reflective material (e.g., metallic or dielectric). The end reflector 114 may also include one or more dielectric layers, such as a multilayer interference coating. The end reflector 114 can be glued or molded to the side of the waveguide 112 opposite the light input surface 113C, as discussed below.

[0242] 27, the end reflector 114 can be a curved mirror (e.g., a spherical or parabolic mirror). Thus, the end reflector 114 may have optical power and may have a focal point. The source 102 can be positioned at the focal point of the end reflector 114 such that light from the source 102 is reflected along a direction parallel to the surface of the spatial light modulator 106 (e.g., parallel to the x-axis), or such that light reflected from the end reflector 114 is substantially collimated, and / or such that light reflected from the turning feature and directed onto the spatial light modulator is substantially collimated. In such an embodiment, the redirecting feature 1314 may include a pair of first and second planar facets 1326, 1328 with an angular separation of approximately 45 degrees between the first and second planar facets 1326, 1328 such that light reflected from the end reflector 114 is redirected approximately normal to the surface of the spatial light modulator 106 (e.g., parallel to the y-axis), as depicted in the inset of FIG.

[0243] In various embodiments, the redirecting feature 1314 can include a polarization-selective element 1318 (e.g., a polarization-selective coating, one or more thin-film coatings, a dielectric coating, or a wire grid) configured to redirect light having a specific polarization state toward the spatial light modulator 106. For example, as shown in the inset of FIG. 27 , a first polarization state (e.g., an s-polarized state) from the light source 102 can be reflected from the end reflector 114 and redirected toward the spatial light modulator 106. However, light of a second, orthogonal polarization state (e.g., a p-polarization state) is transmitted. The modulated light from the spatial light modulator 106 includes light having the second polarization state (e.g., a p-polarization state). This light from the spatial light modulator 106 is transmitted by the polarization-selective element 1318. A clean-up polarizer 1310 can be included and configured to transmit a second polarization state (e.g., a p-polarization state) while blocking the first polarization state (e.g., an s-polarization state). The PBS 1306 can be positioned with respect to the waveguides 270, 280, 290, 300, 310 and the internal coupling elements thereon, discussed above with reference to FIG. 6, such that light from the PBS 1306 can be internally coupled into the waveguides 270, 280, 290, 300, 310.

[0244] 28A, 28B, 28C, and 28D depict various embodiments of turning features including polarization-selective elements. As discussed above, the polarization-selective elements can include a coating or a wire grid. In the embodiment illustrated in FIG. 28A, a pair of facets of each turning feature is at least partially coated with a polarization-selective coating configured to reflect, for example, a first polarization state (e.g., an s-polarization state) and transmit a second polarization state (e.g., a p-polarization state). The polarizing coating may include one or more layers (e.g., multiple thin-film coatings), such as, for example, one or more dielectric layers. The polarization-selective coating can be configured to be broadband, such that the coating reflects a first polarization state (e.g., an s-polarization state) within a wide range of wavelengths within the visible spectral range (e.g., s-polarized light within the red, green, and blue spectral ranges). A PBS coating that selectively reflects a first polarization state and transmits a second polarization state can advantageously provide high contrast (e.g., by efficiently distinguishing between s-polarized and p-polarized states) as selective pixels of the spatial light modulator 106 modulate polarization and produce images. Additionally, multiple thin film coatings that can selectively reflect a first polarization state and transmit a second polarization state can be cheaper and easier to manufacture.

[0245] However, various embodiments of thin film coatings capable of selectively reflecting a first polarization state and transmitting a second polarization state may have a small incidence angle range. For example, some embodiments of thin film coatings capable of selectively reflecting a first polarization state and transmitting a second polarization state may not function efficiently when the acceptance angle of light varies by more than about ±10 degrees from the design incidence angle. For example, if a facet comprising thin film coatings is configured to reflect s-polarized light at an incidence angle of about 45 degrees relative to the normal to the facet, it may not efficiently reflect light when the light is incident at an angle greater than about 55 degrees relative to the normal to the facet or less than about 35 degrees relative to the normal to the facet. As another example, if a facet comprising thin film coatings is configured to reflect p-polarized light at an incidence angle of about 45 degrees relative to the normal to the facet, it may not efficiently transmit light when the light is incident at an angle greater than about 55 degrees relative to the normal to the facet or less than about 35 degrees relative to the normal to the facet.

[0246] Thus, in those embodiments where a wider acceptance angle range is desired, a wire grid can be used to efficiently reflect a first polarization state and transmit a second polarization state. Thus, for example, for embodiments where light reflected from the end reflector 114 is incident on a facet within an angular range of more than about ±10 degrees from the design angle of incidence, a wire grid can be disposed at least partially across one of the facets of the turning feature pair.

[0247] As shown in Figure 28B, a polarization-selective element can be disposed over a portion of the facet that receives light from the end reflector 114. The other facets need not include a polarization-selective element or coating. In the embodiment depicted in Figure 28C, one facet of the turning feature 1314 is tilted at an angle of about 45 degrees relative to a vertical axis parallel to the y-axis, while the other facet is parallel to a horizontal axis parallel to the x-axis. In such an embodiment, the facet that is tilted at an angle of about 45 degrees relative to the vertical axis parallel to the y-axis can include a polarization-selective element, and / or the other facets can lack a polarization-selective element, or at least the tilted facet can include more polarizing beam-splitting coatings than the other facets.

[0248] In various embodiments, the turning feature 1314 can include a first section 1332 having a polarization-selective element separated from a second section 1340 having a polarization-selective element by a section 1336 not having a polarization-selective element, as shown in Figure 28D. Light reflected from the end reflector 114 that does not impinge on a section not having a polarization-selective element (e.g., section 1336) will pass through the turning feature until striking a section having a polarization-selective element. Such an implementation can be advantageous in increasing the uniformity of illumination across the surface of the spatial light modulator 106.

[0249] The PBS 1306 discussed above can have several advantages, including, but not limited to, reduced size compared to conventional PBSs. In various designs, for example, the angled surfaces of the microstructures or turning features 1314 can reflect light reflected from the end reflector 114 so that the light is incident on the spatial light modulator 106 at a normal or near-normal angle without requiring a large tilt angle of the second surface 113B. Angling the second surface 113B at less than 45 degrees allows the PBS 1306 to have a reduced thickness.

[0250] Advantageously, when integrated with the light source 102, the PBS 1306 discussed above can provide collimated illumination that can be used for front-lit (or back-lit) spatial light modulators, such as LCOS. Additionally, the contrast ratio of the spatial light modulator 106 can be increased because the end reflector 114 and turning features 1314 are configured to direct light toward the spatial light modulator 106 along a direction normal or near-normal to the first surface 113A or the spatial light modulator 106 or the front surface of the spatial light modulator 106. Furthermore, the refractive optical element 118 can be configured to absorb any stray light that is not redirected toward the spatial light modulator 106, which can also improve the contrast ratio of the spatial light modulator 106. Additionally, the illumination system 1000 may be capable of color-sequential and color-filter-based operation.

[0251] As discussed above, the turning features 1314 need not be located in a region of the second surface 113B that extends beyond the spatial light modulator 106. For example, with reference to FIG. 27 , light ray 124A that, after being totally internally reflected from the first surface 113A, is incident on a portion of the end reflector 114 outside the box 1322, will be incident on a portion of the surface 113B that does not include the second turning feature 1314 and will therefore not be directed toward the spatial light modulator 106. Furthermore, light emitted along the optical axis of the light source 102 and incident on a portion of the end reflector 114 outside the box 1322 will be reflected back toward the light input surface 113C and will not be directed toward the spatial light modulator 106. Thus, some light emitted from the light source 102 may be wasted, and illumination efficiency may be reduced.

[0252] To increase utilization of the light emitted from the source 102, the end reflector 114 may be tilted and / or the curvature of the end reflector 114 may be varied so that the reflected light converges, for example, toward a focal point or virtual focal point in a region 1344 away from the light source 102, as depicted in Figures 29A and 29B. The light converges toward a location farther from the first surface (e.g., first surface 113A) and the spatial light modulator 106 than from the light source 102. In such an embodiment, a turning feature (e.g., turning feature 1314) may be configured to provide refractive power and redirect light reflected from the end reflector 114 toward the spatial light modulator 106. The turning feature can be configured to have a positive refractive power, as depicted in Figure 29B, or a negative refractive power, as depicted in Figure 29A.

[0253] In various embodiments, the end reflector 114 can include a reflective holographic structure 1348, as shown in FIG. 30 . The reflective holographic structure 1348 can include diffractive features configured to redirect incident light onto the angled surface. The reflective holographic structure 1348 can be configured to provide one or more of the features of the end reflector 114 discussed above. For example, the reflective holographic structure 1348 can be configured to collimate light or provide light that focuses on or near the light source 102. In some cases, the reflective holographic structure 1348 can be configured to focus reflected light away from the light source 102 and further away from the spatial light modulator 106. The reflective holographic structure 1348 can include diffractive features configured to redirect incident light within a wide range of wavelengths (e.g., red, green, and blue wavelengths) and a wide range of angles of incidence (e.g., approximately ±41 degrees relative to the optical axis of the light source 102 along a horizontal axis parallel to the x-axis). The reflective holographic structure 1348 can be configured to collimate light from multiple light sources. In various embodiments, the reflective holographic structure 1348 can be configured to reflect light from a first light source along a first desired direction and light from a second light source along a second desired direction. In this manner, the reflective holographic structure 1348 can reflect light from different sources (e.g., different colored light sources) along different, independently controlled propagation directions set by the design of the reflective holographic structure 1348. The reflective holographic structure may include one or more holograms or diffractive optical elements.

[0254] 31 illustrates an embodiment of a method 1350 for manufacturing an embodiment of the PBS 1306. The method includes providing a waveguide (e.g., waveguide 112) including one or more turning features (e.g., turning feature 1314) and an end reflector (e.g., end reflector 114), as shown in block 1354. As discussed above, the one or more turning features can be formed on a surface (e.g., second surface 113B) of the waveguide (e.g., waveguide 112), for example, by molding. The end reflector can also be molded onto the edge of the waveguide or attached to the edge of the waveguide using an adhesive.

[0255] The method may further include disposing a polarization-selective coating (e.g., comprising multiple thin films, one or more dielectric coatings, or a wire grid) at least partially on the turning features, as depicted in block 1362. The method further includes disposing a refractive optical element (e.g., refractive optical element 118) over the waveguide, as depicted in block 1366. The refractive optical element can be attached to the waveguide using an adhesive. An index-matching layer can be disposed between the refractive optical element and the waveguide. The side of the refractive optical element opposite the side including the end reflector can be configured to absorb any stray light not redirected by the turning features by blackening the surface, as shown in block 1366. Alternatively, a light-absorbing component can be disposed on the side of the refractive optical element opposite the side including the end reflector to absorb stray light not redirected by the turning features.

[0256] In embodiments of illumination systems employing light recycling, such as those shown in Figure 33 discussed herein, the side of the refractive optical element opposite the side including the end reflector and / or a portion of the input surface of the waveguide between the light source and the spatial light modulator (e.g., spatial light modulator 106) can be configured to be reflective. Additionally, a quarter-wave retarder or plate can be positioned adjacent to the reflective portion of the input surface of the light redirecting element between the light source and the spatial light modulator to facilitate light recycling in the manner illustrated in Figure 33.

[0257] In embodiments of illumination systems employing light recycling, such as those shown in Figure 34 discussed herein, a half-wave plate can be positioned on the side of the refractive optical element opposite the side including the end reflector. A second waveguide including one or more turning features and a second spatial light modulator is positioned on the other side of the half-wave retarder or plate to facilitate light recycling in the manner illustrated in Figure 34. Polarization-based light recycling

[0258] When an illumination device includes a light source or light emitter that outputs unpolarized light, some of the light (e.g., light that does not have the desired polarization) remains unused. For example, when an unpolarized emitter such as a light-emitting diode (LED) is combined with a linear polarizer to produce linearly polarized light of the desired orientation, in some cases 50% of the light can be wasted.

[0259] However, various exemplary illumination devices described herein may utilize one or more light emitters configured to emit light having more than one polarization state (e.g., unpolarized or partially polarized), which can advantageously increase the efficiency of the device's light usage. Although these illumination devices emit light of a particular polarization state (e.g., an s-polarized state) onto a spatial light modulator, the light can be modulated. To improve the efficiency of light usage, light that is not emitted to and / or received by the spatial light modulator can be recycled. For example, a light recycling system can be configured to convert light having a polarization state that is not useful for the spatial light modulator (e.g., a p-polarized state) into light of another polarization state (e.g., an s-polarized state) that can be received and appropriately modulated by the spatial light modulator to form an image.

[0260] 32 illustrates an example of a display device incorporating a light recycling system for recycling light, according to one embodiment. The display device 5000 can include at least one light emitter 5010 configured to emit light 5012 having more than one polarization state (e.g., illustrated as an s-polarization state and a p-polarization state). The display device 5000 can further include a light-directing optical element, such as a waveguide 5015, disposed relative to the light emitter 5010 to receive the light 5012 and redirect the light toward at least one spatial light modulator 5025. The waveguide 5015 can emit light 5020 having a first polarization state (e.g., an s-polarization state), which can be modulated by the spatial light modulator 5025 to form an intensity image. Thus, the spatial light modulator 5025 is disposed relative to the waveguide 5015 to receive the light 5020 emitted from the waveguide 5015. As described herein, the display device 5000 can include a light recycling system (e.g., including components 5030a and 5030b) to recycle light that is not emitted from the waveguide 5015 to the spatial light modulator 5025. For example, as shown in FIG. 32 , the light recycling system (e.g., 5030a and 5030b) can be configured to convert light having a second polarization state (e.g., p-polarized light in this example) that is not used by the spatial light modulator 5025 into light 5035 having a first polarization state (e.g., s-polarized light) that is usable by the spatial light modulator 5025. Thus, instead of some light being unused, by converting light having the second polarization state to light having the first polarization state, additional light can be emitted from the waveguide 5015 to the spatial light modulator 5025 and contribute to the image formed by the spatial light modulator 5025. Various features of FIG. 32 will now be described.

[0261] Referring to FIG. 32 , the display device 5000 can include at least one light emitter 5010. The light emitter 5010 can include a single light emitter or more than one light emitter (hereinafter referred to as “light emitter 5010”). The light emitter 5010 can be configured to emit light 5012 having more than one polarization state. For example, the light 5012 can include a first polarization state (e.g., an s-polarization state) and a second polarization state (e.g., a p-polarization state). The light emitter 5010 can also include any of the light emitters disclosed herein or other types of emitters. In some embodiments, the light emitter 5010 can include one or more light emitting diodes (LEDs), such as red LEDs, green LEDs, blue LEDs, and / or white LEDs (WLEDs). As another example, the light emitter 5010 can include one or more superluminescent diodes (SLEDs) or one or more lasers.

[0262] The display device 5000 can also include at least one light-redirecting optical element, which may include a waveguide 5015 positioned relative to the light emitter 5010 and receiving the light 5012 from the light emitter 5010. In various designs, a portion of the light 5012 can be guided within the waveguide 5015 by total internal reflection (TIR). The waveguide 5015 can include any of the light-redirecting optical elements described herein. For example, the waveguide 5015 can include plastic, glass (e.g., in some embodiments, high refractive index glass), or a combination thereof. As described herein, the waveguide 5015 can function as a polarizing beam splitter and reflect light 5020 having a certain polarization state (e.g., in this example, an s-polarization state) to the spatial light modulator 5025. In some embodiments, the waveguide 5015 can have an angled surface 5015a configured to reflect light 5020 having a first polarization state (e.g., an s-polarization state) and transmit light (not shown) having a second polarization state (e.g., a p-polarization state). The waveguide 5015 can include one or more redirecting elements (e.g., on the angled surface 5015a) configured to redirect light guided within the waveguide 5015 (e.g., light having a certain polarization state) out of the waveguide 5015 and toward the spatial light modulator 5025. The angled surface may include polarization-selective elements or structures that can operate differently with respect to different polarization states. For example, the redirecting element can include a redirecting feature (e.g., a microstructure such as one or more microprisms or a dielectric coating on a wire grid configured to direct light having a certain polarization state out of the waveguide 5015) configured to redirect light guided within the waveguide 5015 out of the waveguide 5015. As a result, light propagating within the waveguide 5015 having a desired polarization state (e.g., an s-polarization state) that is incident on the angled surface 5015a can be reflected to exit the waveguide 5015, e.g., from a major surface of the waveguide 5015, e.g., the bottom of the waveguide 5015, and be directed onto the spatial light modulator 5025.A compensation layer 5016 can be disposed over the angled surface 5015a and the turning features thereon. For some designs, the compensation layer 5016 can comprise the same or similar material (e.g., plastic, glass, or a combination thereof) as that for the waveguide 5015. The compensation layer 5016 can reduce the refractive effect of the angled surface 5015a on light passing through the waveguide 5015. The compensation layer 5016 can redirect light reflected from the spatial light modulator 5025 that passes through the waveguide 5015 in response to reflection from the spatial light modulator 5025, which would otherwise be bent by the angled surface 5015a.

[0263] 32 , the display device 5000 can include at least one spatial light modulator 5025, such as a liquid crystal spatial light modulator, that includes an array of pixels that can be independently modulated to form an image. The spatial light modulator 5025 can be positioned relative to the waveguide 5015 and receive light 5020 having a certain polarization state (e.g., an s-polarization state) that exits the waveguide 5015. For example, light having a desired (first) polarization state (e.g., an s-polarization state) that is incident on the angled surface 5015 a can be redirected and directed at an angle such that the light is not guided within the waveguide 5015 or otherwise directed onto the spatial light modulator 5025 from a major surface of the waveguide 5015, such as the bottom surface of the waveguide 5015. The spatial light modulator 5025 can be electrically coupled to electronics configured to drive the spatial light modulator 5025, thereby modulating the light 5020. For example, for a spatial light modulator that modulates polarization, the spatial light modulator 5025 can receive light 5020 having a first polarization state (e.g., an s-polarization state) and output light having either a first or second polarization state (e.g., a p-polarization state) depending on the state of the pixel.

[0264] Light that is not directed out of waveguide 5015 to spatial light modulator 5025, e.g., not in the desired first polarization state (e.g., s-polarization state), may continue to propagate through waveguide 5015. This light may not be reflected out of waveguide 5015 by angled surface 5015a.

[0265] However, as described herein, the display device 5000 can include a light recycling system including elements 5030a and 5030b configured to convert light 5012 having a second polarization state (e.g., a p-polarization state) into light 5035 having a first polarization state (e.g., an s-polarization state). In FIG. 32, the light recycling system includes a reflective element 5030a and a polarization converter element 5030b. The reflective element 5030a can be positioned against the edge of the waveguide 5015 as illustrated in FIG. 32 and can reflect light 5012 that is not emitted to the spatial light modulator 5025 through a major surface of the waveguide 5015, such as the bottom of the waveguide 5015. The edge of the waveguide 5015 can include an edge opposite the light emitter 5010. The reflective element 5030a can be integrated with a surface edge of the waveguide 5015 or can be attached to the edge of the waveguide 5015. The reflective element 5030a can be configured to reflect light that might otherwise escape out the edge of the waveguide 5015 back into it. The reflective element 5030a may include various reflective elements, including various reflective elements described anywhere herein. The reflective element may include metallization or a reflective dielectric coating, such as a coating including one or more dielectric layers, such as a multi-layer interference coating. In some embodiments, the reflective element 5030a may have a surface that includes curvature, such as a concave surface, which may be, for example, at least a portion of a spherical surface, at least a portion of a parabolic surface, etc. In some embodiments, the reflective element 5030a may have a surface that is planar. The reflective element 5030a may include a mirror, such as a collimating mirror. For example, the reflective element 5030a may include a spherical mirror (e.g., a mirror having at least a portion of a spherical shape) or a parabolic mirror (e.g., a mirror having at least a portion of a parabolic shape). In some embodiments, the reflective element 5030a may include a diffractive optical element, such as a grating, a holographic optical element, or another type of reflective surface. The diffractive optical element, grating, holographic optical element, or other structure may, in some instances, be on a planar surface.

[0266] As shown in FIG. 32, the light recycling system may also include a polarization converter element 5030b positioned relative to the reflecting element 5030a, receiving light reflected and / or collimated by the reflecting element 5030a and converting light having a second polarization state (e.g., p-polarization state) to light having a first polarization state (e.g., s-polarization state). The polarization converter element 5030b may include a polarization rotator that rotates the orientation of linearly polarized light. The polarization rotator may rotate vertically polarized light to horizontally polarized light or vice versa, or p-polarized light to s-polarized light or vice versa. The polarization rotator may include a retarder, such as a quarter-wave retarder. Passing through a quarter-wave retarder may, in some cases, introduce a 180° retardation between the two orthogonal polarizations, affecting the rotation of the linear polarization. Therefore, the recycled light may propagate back through the waveguide 5015 as light 5035 having a first polarization state (s-polarization state) and be emitted out of the waveguide 5015 (e.g., via a redirecting element) to the spatial light modulator 5025, improving the efficiency of the display device 5000.

[0267] Although a liquid crystal-based spatial light modulator 5025 is referenced above, the spatial light modulator 5025 may include other types of spatial light modulators, such as a digital light processing (DLP) device or an electronic paper device, which may also include one or more pixels that can be modulated to form an image. In some embodiments, the spatial light modulator 5025 may include a reflective spatial light modulator configured to reflect and modulate light incident thereon. In some embodiments, the spatial light modulator 5025 may include a transmissive spatial light modulator configured to modulate light transmitted through the spatial light modulator.

[0268] Figure 33 illustrates another example of a display device incorporating a light recycling system for recycling light. Similar to Figure 32, the display device 5100 can include one or more light emitters 5110 (hereinafter referred to as "light emitters 5110") configured to emit light having more than one polarization state, and a light redirecting element or waveguide 5115 configured to receive light having a first polarization state (e.g., an s-polarization state) and launch the light out a major surface of the waveguide 5115, such as the bottom or back surface of the waveguide 5115, to the spatial light modulator 5125. The light recycling system can include a reflective element 5130a positioned against an edge of the waveguide 5115 to reflect light that is not launched into the spatial light modulator 5125.

[0269] In some such embodiments, the light emitter 5110 may be positioned relative to the reflective element 5130a to inject light into an edge of the waveguide 5115, possibly off-center, for example, proximate a corner of the waveguide 5115. The edge of the waveguide 5115 may include an edge opposite the reflective element 5130a. As discussed above, the reflective element 5130a may include a curved surface. For example, the reflective element 5130a may include a spherical mirror. The light emitter 5110 may be positioned at or proximate the focal point of the spherical mirror (e.g., the reflective element 5130a). As shown in FIG. 33, the reflective element 5130a may be configured to reflect and / or collimate the reflected light. The reflected light may be directed away from the location of the light emitter 5110, as shown, and may ultimately impinge on a location below the light emitter 5110. The light recycling system may also include a polarization rotator, such as a quarter-wave retarder 5130b, and a second reflective element 5130c positioned relative to the quarter-wave retarder 5130b to retroreflect light from the quarter-wave retarder 5130b incident on the reflective element 5130c through the quarter-wave retarder 5130b. Passage of the pair through the quarter-wave retarder 5130b may, in some cases, introduce a 180° phase difference between the orthogonally polarized components, thereby rotating the linear polarization. The quarter-wave retarder 5130b and the second reflective element 5130c may be positioned at an edge of the waveguide 5115 opposite the first reflective element 5130a and / or at a location where light reflected from the first reflective element 5130a ultimately arrives (e.g., below the light emitter 5110). The quarter-wave retarder 5130b may be configured to be transmissive and thus allow light reflected by the first reflective element 5130a to pass to the second reflective element 5130c. The second reflective element 5130c can be configured to reflect light back to the quarter-wave retarder 5130b. In some embodiments, the second reflective element 5130c may include a reflective coating, such as a mirror coating.Upon two passes through the quarter-wave retarder 5130b, the light 5113 having the second polarization state (e.g., p-polarization state) can be converted into recycled light 5135 having the first polarization state (e.g., s-polarization state).

[0270] The quarter-wave retarder 5130b may be a birefringent material (e.g., quartz) that is sized and oriented to provide a quarter-wave phase retardation between orthogonal linear polarizations, or to retard one component by a quarter wavelength relative to the other. After passing through the quarter-wave retarder 5130b, the linearly polarized light is redirected to a circular polarization state and can propagate towards the reflective element 5130c.

[0271] The reflective element 5130c can change the handedness of the polarization of light while reflecting it back towards the quarter-wave retarder 5130b. In some embodiments, the reflective element 5130c may be made from several layers of dielectric material. Similarly, the reflective element 5130c can be tuned to the wavelength of the light from the light emitter 5110, thus facilitating increased reflectivity.

[0272] In response to passing through the quarter-wave retarder 5130b a second time, the light is changed from circularly polarized back to linearly polarized, where it may have a rotated linear polarization state (e.g., an s-polarization state). The recycled light may counter-propagate within the waveguide 5115 as recycled light 5135 having the desired first polarization state and be ejected out of the waveguide 5115 (e.g., via a turning feature) to the spatial light modulator 5125, improving the efficiency of the display device 5100.

[0273] As described herein, the waveguide 5115 can function as a polarizing beam splitter and reflect light having a certain polarization state to the spatial light modulator 5125. In some embodiments, the waveguide 5115 can have an angled surface 5115a (e.g., which may include turning features) that reflects light having a first polarization state (e.g., an s-polarization state) and transmits light 5140 having a second polarization state (e.g., a p-polarization state). As discussed above, the compensation layer 5116 can be disposed across the angled surface 5115a. As shown, the light recycling system includes a third reflective element 5130d positioned to receive the collimated light reflected from the first reflective element 5130a. The reflective element 5130d can be positioned against an edge of the waveguide 5115 (e.g., an edge of the compensation layer 5116 opposite the reflective element 5130a). In some embodiments, the reflective element 5130d can include the same or similar material as that of the reflective element 5130c. For example, the reflective element 5130d can include a mirror coating. The reflective element 5130d can be configured to retroreflect light 5140 transmitted by the angled surface 5115a, such as light having a second polarization state (e.g., p-polarization state), back into the waveguide 5115 as light 5145. This light 5145 reflected from the reflective element 5130d can be in the second polarization state (e.g., p-polarization state) and can be reflected again by the first reflective element 5130a to the quarter-wave retarder 5130b. The light can continue through the quarter-wave retarder 5130b to its associated second reflective element 5130c and be reflected again through the quarter-wave retarder 5130b, thereby rotating its polarization state. Thus, light directed to the quarter-wave retarder 5130b can be rotated to a polarization state (e.g., an s-polarization state) that can be emitted out of the waveguide 5115, for example, upon reflection from the angled surface 5115a.For example, linearly polarized light having a second polarization state (e.g., p-polarization state) is converted to recycled light 5135 having a first polarization state (e.g., s-polarization state) by other components of the light recycling system, such as reflective element 5130a, reflective element 5130d, quarter-wave retarder 5130b, and reflective element 5130c. This light is again reflected from first reflective element 5130a to angled surface 5115a, which selectively reflects the first polarization state (e.g., s-polarization state). The recycled light 5135 having the first polarization state (e.g., s-polarization state) can then be emitted out of waveguide 5115 (e.g., via a redirecting element on the angled surface) to spatial light modulator 5125, improving the efficiency of display device 5100.

[0274] Figure 34 illustrates another example of a display device incorporating a light recycling system for recycling light. Similar to Figures 32 and 33, the display device 5200 may include one or more light emitters 5210 (hereinafter referred to as "light emitters 5210") configured to emit light having more than one polarization state, and a waveguide 5215 configured to receive light 5212 and launch light 5220 having a first polarization state (e.g., an s-polarization state) to a spatial light modulator 5225. The light recycling system may include a reflective element 5230a positioned against an edge of the waveguide 5215 to reflect light received from the light emitter 5210.

[0275] As described herein, the waveguide 5215 can function as a polarizing beam splitter and reflect light 5220 having one polarization state (e.g., an s-polarization state) to the spatial light modulator 5225. In some embodiments, the waveguide 5215 can have an angled surface 5215a (e.g., which can include a redirecting element) to reflect light 5220 having a first polarization state (e.g., an s-polarization state) and transmit light 5240 having a second polarization state (e.g., a p-polarization state). Thus, light from the light emitter 5210 having a first polarization state (e.g., an s-polarization state) reflected by the first reflective element 5230a to the angled surface 5215a is reflected toward the spatial light modulator 5225. This light can be reflected from the spatial light modulator 5225 and passed through the waveguide 5215 and the angled surface 5215a. In particular, light having a second polarization state (e.g., a p-polarization state), e.g., light having a polarization rotated by selective pixels of spatial light modulator 5225, may pass through waveguide 5215 and angled surface 5215a. Compensation layer 5216, as described above, may be disposed over angled surface 5215a to counteract refraction otherwise caused by angled surface 5215a.

[0276] To improve the efficiency of light use, the light recycling system can also include a polarization rotator, such as a half-wave retarder 5230b. The half-wave retarder 5230b can be positioned relative to the edge of the waveguide 5215, for example, on or proximate to the edge of the compensation layer 5216 opposite the reflective element 5230a. In some designs, the half-wave retarder 5230b can be configured to be transmissive, thereby allowing light 5240 transmitted by the angled surface 5215a to pass to the second light redirecting element or waveguide 5245. The half-wave retarder 5230b can also be configured to convert light 5240 having a second polarization state (e.g., a p-polarization state) to light 5250 having a first polarization state (e.g., an s-polarization state). The recycled light 5250 having the first polarization state (e.g., s-polarization state) can then be launched out of the second waveguide 5245 (e.g., via a redirecting element) into the second spatial light modulator 5260 to further improve the efficiency of the device. For example, the second waveguide 5245 can function as a polarizing beam splitter as described herein. The second waveguide 5245 can include an angled surface 5245a (e.g., which can include a redirecting element) to reflect the light 5255 having the first polarization state (e.g., s-polarization state) into the second spatial light modulator 5260. Similarly, the second waveguide 5245 can include a second optical compensation layer 5246 to counteract refraction otherwise caused by the angled surface 5245a.

[0277] As illustrated in the design shown in Figure 34, a light emitter 5210 and a half-wave retarder 5230b are positioned between two waveguides 5215 and 5245. Other configurations are also possible.

[0278] Although Figures 32-34 are illustrated with waveguides 5015, 5115, 5215 having angled surfaces 5015a, 5115a, 5215a, various embodiments, including light recycling systems, may be incorporated into waveguides having substantially planar surfaces. For example, Figures 35 and 36 illustrate two such examples. In some such embodiments, the display device 5300, 5400 may include at least one light emitter 5310, 5410 configured to emit light 5312, 5412 having more than one polarization state and a waveguide 5315, 5415 configured to receive the light 5312, 5412. The waveguide 5315, 5415 may emit light 5320, 5420 having a first polarization state (e.g., an s-polarization state) to a spatial light modulator 5325, 5425.

[0279] In various embodiments, the device 5300, 5400 can include one or more redirecting elements 5327, 5427a disposed relative to the waveguide 5315, 5415 (e.g., on or adjacent to the waveguide surface 5315a, 5415a) and redirecting light guided in the waveguide 5315, 5415 out of the waveguide 5315, 5415 to the spatial light modulator 5325, 5425. The redirecting element 5327, 5427a can include one or more redirecting features configured to redirect light 5320, 5420 guided in the waveguide 5315, 5415 out of the waveguide 5315, 5415. The redirecting element 5327, 5427a can include one or more nanostructures or microstructures configured to emit light 5320, 5420 having a first polarization state (e.g., an s-polarization state) out of the waveguide 5315, 5415. The redirecting element may include, for example, one or more diffractive optical elements, such as gratings, holographic optical elements, or other structures.

[0280] In some embodiments, the redirecting element can include a polarization-sensitive redirecting element. The polarization-sensitive redirecting element may include a polarization-sensitive microstructure or nanostructure. The polarization-sensitive redirecting element may include a grating (e.g., highly sensitive), a diffractive optical element, a holographic optical element, etc. As illustrated in FIG. 35 , some such nanostructures or gratings can direct light 5320 having a first polarization state (e.g., s-polarization state) to a spatial light modulator 5325, while light 5322 having a second polarization state (e.g., p-polarization state) can continue to propagate through the waveguide 5315. For example, light having a polarization redirected by the nanostructure or grating (e.g., first polarization state) can be outcoupled and / or reflected toward the spatial light modulator 5325, while light having a polarization not redirected by the nanostructure or grating (e.g., second polarization state) can continue to propagate through the waveguide 5315.

[0281] In some embodiments, the nanostructures or gratings may not include polarization-sensitive nanostructures or gratings, as illustrated by Figure 36. In some such embodiments, device 5400 may also include a wire grid 5427b disposed between waveguide 5415 (e.g., on or adjacent to waveguide surface 5415a) and one or more nanostructures or gratings (e.g., 5427a).

[0282] Wire grid 5427b may be tuned to the wavelength of the light produced by light emitter 5410 so as to reflect light of a particular polarization state and transmit light of another polarization state. For example, as illustrated in FIG. 36, wire grid 5427b can be configured to transmit light 5420 having a first polarization state (e.g., s-polarization state) to one or more nanostructures or gratings (e.g., 5427a) and reflect light 5422 having a second polarization state (e.g., p-polarization state). The nanostructures or gratings (e.g., 5427a) can then direct light 5420 having the first polarization state (e.g., s-polarization state) to spatial light modulator 5425, while light 5422 having the second polarization state (e.g., p-polarization state) can continue propagating through waveguide 5415.

[0283] 35 and 36, various embodiments can incorporate a light recycling system to convert light 5322, 5422 having a second polarization state (e.g., a p-polarization state) propagating through waveguides 5315, 5415 to light 5335, 5435 having a first polarization state (e.g., an s-polarization state). The light recycling system can include a reflective element 5330a, 5430a and a quarter-wave retarder 5330b, 5430b.

[0284] The quarter-wave retarders 5330b, 5430b may be transmissive and positioned against the edges of the reflective elements 5330a, 5430a, allowing light that reaches the edge waveguides 5315, 5415 and is not emitted to the spatial light modulators 5325, 5425 to pass through to the reflective elements 5330a, 5430a after undergoing a 90° phase shift between orthogonal polarization states. The reflective elements 5330a, 5430a can be configured to retroreflect the light back to the quarter-wave retarders 5330b, 5430b. As described with respect to FIG. 33 , in response to passing twice through the quarter-wave retarders 5330b, 5430b, the light 5322, 5422 undergoes a 180° phase shift between orthogonal polarization states. As a result, the second polarization state (e.g., p-polarization state) can be converted into light 5335, 5435 having the first polarization state (e.g., s-polarization state). Some such recycled light 5335, 5435 having the first polarization state (e.g., s-polarization state) can counter-propagate within the waveguide 5315, 5415 and be ejected out of the waveguide 5315, 5415 (e.g., via a redirecting element). Instead of the light with the second polarization state (e.g., p-polarization state) being used, the light with the second polarization state (e.g., p-polarization state) can be converted into light with the first polarization state (e.g., s-polarization state) that can be directed to and used by the spatial light modulator 5325, 5425 to contribute to producing an image, thereby improving the efficiency of the device.

[0285] 35 and 36, some embodiments can also include a polarizer 5350, 5450 between the waveguide 5315, 5415 and the spatial light modulator 5325, 5425. Such a polarizer 5350, 5450 can be used to produce an intensity image from the spatial light modulator 5325, 5425, which operates on polarized light and selectively modulates the polarization state. The polarizer 5350, 5450 can transmit one linear polarization state and attenuate another polarization state, such that the spatial light modulator 5325, 5425 has the effect of controlling intensity on a pixel-by-pixel basis by selectively controlling the polarization state on a pixel-by-pixel basis.

[0286] As described herein with respect to Figures 32-36, various designs can include light recycling systems to improve the efficiency of light use in the device. Various features described with respect to other devices described herein can be incorporated with any feature or combination of features of a device, including a light recycling system. Additionally, the exemplary light recycling systems described herein or any feature or combination thereof can be incorporated into any of the other designs described herein or combined with any feature or combination of features of any other design described herein.

[0287] FIG. 37 illustrates an illumination device 1400 with an internal coupling element 1654 that deflects light to couple into a waveguide 1412, where the internal coupling element 1654 is parallel to the internal coupling surface 1652 and the surface closest to the spatial light modulator 1408. The internal coupling element 1654 may include a diffraction grating or other diffractive optical element. In some designs, the internal coupling element 1654 may be reflective and include, for example, a dielectric coating (e.g., an interference coating). The internal coupling element 1654 may also include micro- and / or nano-prism structures. As shown in FIG. 37 , a light emitter 1650 launches light into the waveguide 1412 at the internal coupling surface 1652. At least a portion of the light (e.g., light of a certain polarization) is deflected (e.g., diffracted, reflected, etc.). The light may propagate through the waveguide 1412 via TIR. The waveguide 1412 may include a planar waveguide. The waveguide 1412 further includes a light redirecting feature 1416 positioned to receive light propagating within the waveguide by TIR and to eject at least a portion of the light incident thereon. The light redirecting feature 1416 is configured to eject light 1663 toward the spatial light modulator 1408. The spatial light modulator 1408 may be positioned opposite the light redirecting feature 1416 to receive light ejected by the light redirecting feature 1416. As shown, the exiting light 1663 may be reflected by the spatial light modulator 1408 (e.g., in a reflective mode). In some embodiments (e.g., a transmissive mode), the exiting light 1663 may be at least partially transmitted through the spatial light modulator 1408. As shown in FIG. 37 , the modulated light 1665 may propagate through the waveguide 1412 toward the output area 1436.

[0288] The polarizing beam splitter and illumination system, as disclosed herein, may have various applications. For example, such a beam splitter and illumination system may operate together within an augmented reality display device. The illumination system may be configured in optical communication with an eyepiece. In some implementations, the eyepiece may include one or more waveguides positioned within a user's field of view. As described herein, an image can be presented to the user's eye as the eye looks through the eyepiece. In certain implementations, the eyepiece includes a waveguide stack, although the use of the polarizing beam splitter and illumination system as described herein should not be so limited. FIG. 38 shows an example illumination system 1000 coupled to an eyepiece, specifically coupled to a waveguide stack 166 within the eyepiece. The illumination system 1000 may include any one or more features of the illumination systems described herein. Additionally or alternatively, the waveguide stack 166 may include one or more features described with respect to a waveguide, a waveguide stack (e.g., with respect to FIGS. 9A-9C ), or an eyepiece. The transmitted light 132 may be received by one or more in-coupling optical elements 144, 146, 148. The illumination system 1000 can be in optical communication with (e.g., disposed along its optical axis) the waveguide stack 166. In some implementations, the illumination system 1000 can be configured to abut one or more elements of the waveguide stack 166 or can be separated therefrom. For example, the refractive optical element 118 can abut a surface of the waveguide 158 and / or the in-coupling optical element 148. However, abutment is not required. The illumination system 1000 can be configured to direct light (e.g., the transmitted light 132) into the waveguide stack 166. In some embodiments, the transmitted light 132 may propagate between the illumination system 1000 and the waveguide stack 166 via a waveguide (e.g., an optical fiber). The transmitted light 132 may propagate through a transmissive medium (e.g., plastic, glass, air, etc.) between the polarizing beam splitter 104 and the waveguide stack 166. Other variations are possible.

[0289] One or more internal coupling optical elements 144, 146, 148 can be configured to couple light into corresponding waveguides 154, 156, 158. In some embodiments, one or more internal coupling optical elements 144, 146, 148 can be configured to couple light of a particular wavelength (e.g., red, blue, green, etc.). Additionally or alternatively, in certain implementations, one or more internal coupling optical elements 144, 146, 148 can be configured to couple light of a corresponding depth plane (see, e.g., FIG. 6). The illumination module 102 may correspond to other elements described herein, such as optical module 540 (FIG. 6). The polarizing beam splitter 104 may correspond to other elements described herein, such as beam splitter 550 (FIG. 6).

[0290] Thus, the light sources and illumination modules described herein can be used with or without polarizing beam splitters and / or wedge waveguides to illuminate a spatial light modulator and produce an image that is directed into the eyepiece and displayed to the viewer. A wide variety of variations of such systems (and subsystems and components) are also possible.

[0291] Similarly, any property or characteristic discussed herein with respect to an illumination module, a polarizing beam splitter, a wedge waveguide, an optical integrator, combinations thereof, and / or components, such as in connection with an eyepiece or display, such as an augmented or virtual reality display, can be applied to the structures and concepts discussed anywhere in this specification. Similarly, any property, characteristic, or concept discussed herein with respect to an eyepiece or display, such as an augmented or virtual reality display, a head-mounted display, components thereof, or any combination thereof, can be applied to other structures, features, or concepts described herein, such as an illumination module, a polarizing beam splitter, a wedge waveguide, an optical integrator, combinations thereof, and / or components. Thus, any property or characteristic discussed herein can be applied to other structures and concepts discussed anywhere in this specification. Illustrative Aspects (Example) (Example Section I) 1. A head-mounted display system configured to project light into a user's eye and display augmented reality image content within the user's field of view, comprising: a frame configured to be supported on a user's head; and an eyepiece disposed on the frame, at least a portion of the eyepiece being transparent, the transparent portion being positioned in front of the user's eye when the user wears the head mounted display so as to transmit light from an environment in front of the user to the user's eye to provide a view of the environment in front of the user, the eyepiece comprising one or more waveguides positioned to direct light into the user's eye; a light source configured to emit light; and A wedge-shaped light redirecting element, a first surface parallel to the axis; a second surface opposite the first surface and inclined relative to the axis by a wedge angle α; a light input surface between the first surface and the second surface, the light input surface being configured to receive light emitted from the light source; an edge reflector disposed on a side opposite the light input surface; a wedge-shaped light redirecting element, the second surface of which is angled such that the height of the light input surface is less than the height of an end reflector opposite the light input surface, such that light coupled into the wedge-shaped light redirecting element is reflected by the end reflector and redirected by the second surface towards the first surface; a spatial light modulator positioned relative to the wedge-shaped light redirecting element to receive and modulate the light emitted from the wedge-shaped light redirecting element; wherein the wedge-shaped light redirecting element and the spatial light modulator are positioned relative to the eyepiece to direct modulated light into the one or more waveguides of the eyepiece such that the modulated light is directed into a user's eye and forms an image therein. 2. The system of example 1, wherein the wedge-shaped light redirecting element comprises a polarization-selective element on a second surface, the polarization-selective element configured to redirect light reflected by the end reflector toward the first surface. 3. The system of any one of examples 1 to 2, wherein the polarization selective element comprises a liquid crystal. 4. The system of any of Examples 1-3, wherein the polarization selective element comprises a cholesteric liquid crystal. 5. The system of any of Examples 1-4, wherein the polarization selective element comprises a liquid crystal grating. 6. The system of any of Examples 1-5, wherein the polarization selective element comprises a cholesteric liquid crystal grating. 7. A system described in any of Examples 1-6, wherein the polarization selective element comprises multiple layers of liquid crystals, different liquid crystal layers configured to diffract different wavelengths such that light of different wavelengths is directed toward the first surface. 8. A system described in any of Examples 1-7, wherein the polarization selective element comprises multiple layers of cholesteric liquid crystals, different cholesteric liquid crystal layers configured to diffract different colors such that light of different colors is directed toward the first surface. 9. The system of Example 1, wherein the wedge-shaped light redirecting element comprises a plurality of redirecting features disposed on the second surface, the plurality of redirecting features configured to redirect light reflected by the end reflector toward the first surface. 10. The system of example 9, wherein the plurality of redirecting features comprises polarization-selective elements. 11. The system of example 10, wherein the polarization-selective element comprises a thin film, a dielectric coating, or a wire grid. 12. The system of any of Examples 9 or 10, wherein the plurality of redirecting features are configured to redirect a portion of light received through the light input surface having a first polarization state toward the spatial light modulator. 13. The system of example 12, wherein the wedge-shaped light redirecting element is configured to transmit a portion of the light reflected from the spatial light modulator having the second polarization state. 14. A system according to any of Examples 10-13, wherein the plurality of turning features comprises prismatic turning features. 15. A system described in any of Examples 10-14, wherein the turning feature comprises first and second portions, the first portion having a reflective coating thereon and the second portion not having the reflective coating. 16. The system of example 15, wherein the first and second portions comprise first and second facets. 17. The system of any of Examples 15-16, wherein the reflective coating may comprise a dielectric reflective coating. 18. The system of any of Examples 15-16, wherein the reflective coating may comprise a polarizing coating. 19. The system of any of Examples 10-17, wherein the turning feature has a curved surface. 20. The system of any of Examples 10-18, wherein the plurality of turning features are shaped to have positive optical power. 21. The system of any of Examples 10-18, wherein the plurality of turning features are shaped to have negative optical power. 22. A system described in any of Examples 10-20, wherein the plurality of turning features have a pitch of 20 to 200 micrometers. 23. The system of any of Examples 1-22, wherein the end reflector comprises a curved reflector. 24. The system of example 23, wherein the end reflector comprises a spherical or parabolic mirror. 25. The system of any of Examples 1-22, wherein the end reflector comprises a reflective holographic structure comprising one or more holograms. 26. The system of any of Examples 1-22, wherein the end reflector is configured to collimate light from the light source and direct the collimated light toward the second surface. 27. A system described in any of Examples 1-26, wherein the spatial light modulator is a reflective spatial light modulator and the wedge-shaped light redirecting element is configured to transmit light reflected from the spatial light modulator therethrough. 28. The system of any of Examples 1-27, further comprising a refractive optical element disposed over the light redirecting element configured to compensate for refraction otherwise caused by the wedge-shaped light redirecting element. 29. The system of Example 28, wherein the refractive optical element has a shape that complements the wedge-shaped light redirecting element so as to reduce bending of light from the second surface of the wedge-shaped light redirecting element. 30. The system of any of examples 28 or 29, wherein the refractive optical element has a wedge shape. 31. The system of any of Examples 28-30, further comprising a polarization-selective component disposed across the refractive optical element. 32. A system described in any of Examples 28-31, wherein the refractive optical element has a surface opposite the first surface of the wedge-shaped light redirecting element, and the surface opposite the first surface of the wedge-shaped light redirecting element has an anti-reflective coating thereon. 33. The system of any of Examples 1-32, wherein the light input surface includes an anti-reflective coating thereon. 34. The system of any of Examples 28-33, wherein the refractive optical element has a surface opposite the end reflector, and the surface opposite the end reflector has an absorbing coating thereon. 35. The system of any of Examples 1-34, wherein the wedge angle α is between about 15 degrees and about 45 degrees. 36. A system described in any of Examples 1-35, wherein a light source is coupled into a wedge-shaped light redirecting element through the input surface, and the system is positioned relative to the input surface such that light from the source is reflected by an end reflector and redirected by multiple redirecting features toward the first surface within an angular range of approximately 10 degrees relative to a normal to the first surface. 37. A system according to any of Examples 1-36, wherein the wedge-shaped light redirecting element comprises a waveguide and light from the light source is totally internally reflected from at least the first surface. 38. The system of any of Examples 1-37, wherein the end reflector is configured to collimate light from the emitter incident thereon. 39. The system of any of Examples 1-38, wherein the input light surface includes turning features thereon to redirect light from the light source. 40. A system described in any of Examples 1-39, wherein the input light surface is orthogonal to the axis. 41. A system according to any of Examples 1-40, wherein the input light surface is tilted perpendicular to the axis. 42. A system described in any of Examples 1-41, wherein the light source has an output surface and an air gap is disposed between at least a portion of the output surface of the light source and the input light surface of the wedge-shaped light redirecting element. 43. A system according to any of Examples 1-42, wherein the light source has an output surface, and at least a portion of the output surface of the light source contacts the input light surface of the wedge-shaped light redirecting element. 44. The system of any of Examples 1-43, further comprising a polarizer configured to deflect light input from the light source through the input light surface. 45. A system described in any of Examples 1-44, wherein the light source is in optical communication with the input light surface of the wedge-shaped light redirecting element via an optical fiber. 46. ​​A system described in any of Examples 1-45, wherein the light source comprises at least one of a laser or an LED. 47. A system described in any of Examples 1-46, wherein the light source is configured to deliver at least red, green, and blue light into the wedge-shaped light redirecting element through the light input surface. 48. A system described in any of Examples 1-47, wherein the light source comprises a plurality of emitters or lighting modules configured to output light. 49. A system described in any of Examples 1-48, wherein each of the multiple emitters or lighting modules emits light of a different color. 50. The system of any of Examples 1-49, wherein the different colored lights comprise red light, green light, and blue light. 51. A system described in any of Examples 1-50, wherein the light source comprises two emitters or two lighting modules configured to output light. 52. A system described in any of Examples 1-50, wherein the light source comprises three emitters configured to output light. 53. A system described in any of Examples 1-52, wherein the wedge-shaped light redirecting element and the one or more waveguides have a length along a direction parallel to the axis, and the length of the wedge-shaped light redirecting element is less than 1 / 3 of the length of the one or more waveguides. 54. A system described in any of Examples 1-53, wherein the wedge-shaped light redirecting element has a length along a direction parallel to the axis, the length being less than 10 mm. 55. A system described in any of Examples 1-54, wherein one or more waveguides in the eyepiece lens include one or more internal coupling optical elements, and the wedge-shaped light redirecting element and spatial light modulator are positioned relative to the one or more internal coupling optical elements that direct light from the spatial light modulator therein. (Example Section II) 1. An optical device comprising: A wedge-shaped light redirecting element, a first surface parallel to a horizontal axis; a second surface opposite the first surface and inclined relative to the horizontal axis by a wedge angle α; a light input surface between the first surface and the second surface, the light input surface being configured to receive light emitted from the light source; an edge reflector disposed on a side opposite the light input surface; a plurality of light redirecting features disposed on the second surface; Equipped with the second surface is inclined such that the height of the light input surface is less than the height of a reflective side opposite the light input surface; Light coupled into the wedge-shaped light redirecting element is reflected by the end reflector and redirected by the plurality of redirecting features toward the first surface. An optical device comprising a wedge-shaped light redirecting element. 2. The optical device of example 1, wherein the plurality of redirecting features comprises polarization-selective elements. 3. The optical device of example 2, wherein the polarization-selective element comprises a thin film, a dielectric coating, or a wire grid. 4. An optical device described in any of Examples 1-3, wherein the end reflector comprises a spherical or parabolic mirror configured to redirect light received through the light input surface along a direction parallel to the horizontal axis. 5. The optical device of any of Examples 1-3, wherein the end reflector comprises a reflective holographic structure comprising one or more holograms. 6. An optical device described in any of Examples 1-5, further comprising a spatial light modulator positioned relative to the first surface such that light coupled through the input surface into the wedge-shaped light redirecting element is reflected by an end reflector and redirected by a plurality of redirecting features toward the first surface to the spatial light modulator. 7. An optical device described in any of Examples 1-6, wherein the plurality of redirecting features are configured to redirect a portion of light received through the light input surface having a first polarization state toward the spatial light modulator. 8. An optical device described in any of Examples 1-7, wherein the plurality of redirecting features are configured to transmit a portion of light reflected from the spatial light modulator having a second polarization state. 9. The optical device of any of Examples 1-8, further comprising a light redirecting element disposed over the refractive optical element. 10. The optical device of example 9, further comprising a polarization-selective component disposed over the refractive optical element. 11. The optical device according to any one of Examples 1 to 10, wherein the wedge angle α is between about 15 degrees and about 45 degrees. 12. An optical device described in any of Examples 1-11, further comprising a light source positioned relative to the input surface such that light from the source coupled through the input surface into the wedge-shaped light redirecting element is reflected by the end reflector and redirected by the multiple redirecting features toward the first surface within an angular range of approximately 10 degrees relative to a normal to the first surface. 13. The optical device of any of Examples 1-12, wherein the end reflector is configured to collimate light from the emitter incident thereon. (Example Section III) 1. A display device, comprising: one or more light emitters configured to emit light having more than one polarization state; a waveguide positioned relative to the one or more light emitters to receive light from the one or more light emitters such that at least a portion of the light is guided therein by total internal reflection, the waveguide being configured to emit light having a first polarization state out of the waveguide; a spatial light modulator disposed relative to the waveguide, receiving light emitted from the waveguide and modulating the light; a light recycling system configured to convert light having the second polarization state to light having the first polarization state; A display device comprising: 2. The display device of example 1, wherein the light recycling system comprises a reflective element positioned against an edge of the waveguide to reflect light that is not emitted to the spatial light modulator. 3. The display device of Example 2, wherein the light recycling system comprises a quarter-wave retarder positioned relative to the reflective element to allow light not emitted to the spatial light modulator to pass through the reflective element, the reflective element configured to reflect light back to the quarter-wave retarder such that light having a second polarization state is converted to light having a first polarization state. 4. The display device of any of Examples 1-3, further comprising one or more redirecting elements positioned relative to the waveguide to redirect light guided within the waveguide out of the waveguide and toward the spatial light modulator. 5. The display device of example 4, wherein the one or more redirecting elements comprise one or more redirecting features configured to redirect light guided within the waveguide out of the waveguide. 6. The display device of example 4 or 5, wherein the one or more redirecting elements comprise one or more microstructures or nanostructures configured to eject light having a first polarization state out of the waveguide. 7. The display device of Example 6, further comprising a wire grid disposed between the waveguide and the one or more microstructures or nanostructures, the wire grid configured to transmit light having a first polarization state to the one or more microstructures or nanostructures and reflect light having a second polarization state. 8. The display device of example 6 or 7, wherein the one or more microstructures or nanostructures comprise one or more diffractive or holographic optical elements. 9. The display device of example 2, wherein the waveguide comprises an angled surface for reflecting light having a first polarization state to the spatial light modulator and transmitting light having a second polarization state. 10. The display device of Example 9, wherein the light recycling system comprises a polarization converter element positioned relative to the reflective element, receiving light reflected by the reflective element, and converting light having a second polarization state to light having a first polarization state. 11. The display device of Example 9, wherein the light recycling system comprises a quarter-wave retarder positioned relative to the reflective element and allowing light reflected by the reflective element to pass to a second reflective element configured to reflect the light back to the quarter-wave retarder, whereby light having a second polarization state is converted to light having a first polarization state. 12. The display device of Example 11, wherein the one or more light emitters are disposed at a location relative to the waveguide, and the reflective element is configured to reflect light away from the location of the one or more light emitters. 13. The display device of example 11 or 12, wherein the second reflective element comprises a reflective coating. 14. The display device of any of Examples 11-13, wherein the light recycling system further comprises another reflective element positioned against another edge of the waveguide and reflecting light transmitted by the angled surface. 15. The display device of example 14, wherein the other reflective element comprises a reflective coating. 16. The display device of Example 9, further comprising a second waveguide, wherein the light recycling system further comprises a half-wave retarder configured to allow light transmitted by the angled surface to pass into the second waveguide, the half-wave retarder configured to convert light having a second polarization state to light having a first polarization state. 17. The display device of Example 16, further comprising a second spatial light modulator, wherein the second waveguide is configured to emit light having a first polarization state into the second spatial light modulator. 18. The display device of example 17, wherein the second waveguide comprises a second angled surface that reflects light having a first polarization state to the second spatial light modulator. 19. The display device of any of Examples 16-18, wherein a half-wave retarder is disposed between the first waveguide and the second waveguide. 20. The display device of any of Examples 9-19, wherein the reflective element has a curvature. 21. The display device of example 20, wherein the reflective element comprises a spherical mirror. 22. The display device of any of Examples 9-19, wherein the reflective element comprises a holographic optical element. 23. A display device described in any of Examples 9-22, wherein the waveguide comprises one or more redirecting elements configured to redirect light guided within the waveguide out of the waveguide and toward the spatial light modulator. 24. The display device of Example 23, wherein the one or more redirecting elements comprise one or more redirecting features configured to redirect light guided within the waveguide out of the waveguide. 25. The display device of example 23 or 24, wherein the one or more redirecting elements comprise one or more microstructures. 26. The display device of example 25, wherein the one or more microstructures comprise a dielectric coating on one or more microprisms. 27. The display device of example 25, wherein the one or more microstructures comprise a wire grid. 28. The display device of any of Examples 1-27, wherein the one or more light emitters comprise one or more light emitting diodes (LEDs). 29. The display system of any one of Examples 1-27, wherein the one or more light emitters comprise one or more lasers. 30. The spatial light modulator is configured to reflect and modulate light incident thereon. 30. The display device of any one of Examples 1-29, comprising a reflective spatial light modulator. 31. The spatial light modulator is configured to modulate light transmitted through the spatial light modulator. 30. The display device of any of Examples 1-29, comprising a transmissive spatial light modulator. (Example Section IV) 1. An optical device comprising: a first surface parallel to a horizontal axis; a second surface opposite the first surface and inclined relative to the horizontal axis by a wedge angle α; a wedge-shaped light redirecting element comprising: a light module configured to generate light; a fiber delivery system comprising an optical fiber in optical communication with the optical module for receiving light therefrom; a light input surface between the first surface and the second surface, positioned relative to the light delivery system, for receiving light emitted from the light module via an optical fiber; an edge reflector disposed on a side opposite the light input surface; Equipped with the second surface is inclined such that the height of the light input surface is less than the height of a reflective side opposite the light input surface; Light coupled into the wedge-shaped light redirecting element is reflected by the end reflector and reflected from the second surface towards the first surface. Optical devices. 2. The device of example 1, wherein the optical fiber comprises a multimode fiber. 3. The device of example 1 or 2, wherein the optical fiber comprises polarization-maintaining fiber. 4. A device according to any one of Examples 1-3, wherein the optical module comprises a plurality of optical emitters. 5. The device of example 4, wherein the plurality of light emitters comprises light emitters of different colors. 6. A device described in any of Examples 1-5, wherein the optical module comprises at least one laser. 7. The device of any of Examples 1-5, wherein the optical module comprises a light-emitting diode. 8. The device of example 7, wherein the light emitting diode comprises a plurality of different colored light emitting diodes. 9. The device of example 7, wherein the light-emitting diode comprises a superluminescent diode. (Example Section V) 1. An optical device a first surface parallel to a horizontal axis; a second surface opposite the first surface and inclined relative to the horizontal axis by a wedge angle α; a wedge-shaped light redirecting element comprising: an optical module comprising a laser configured to generate light; an optical input surface between the first surface and the second surface, in optical communication with the optical module and adapted to receive light emitted from the laser; an edge reflector disposed on a side opposite the light input surface; Equipped with the second surface is inclined such that the height of the light input surface is less than the height of a reflective side opposite the light input surface; An optical device wherein light coupled into the wedge-shaped light redirecting element is reflected by the end reflector and reflected from the second surface towards the first surface. 2. The device of example 1, wherein the laser comprises a fiber laser. 3. The device of example 1 or 2, wherein the at least one laser comprises a plurality of different colored lasers. (Example Section VI) 4. An optical device comprising: a first surface parallel to a horizontal axis; a second surface opposite the first surface and inclined relative to the horizontal axis by a wedge angle α; a wedge-shaped light redirecting element comprising: an optical module comprising a plurality of light emitters, the optical module combining light for the plurality of emitters; a light input surface positioned relative to the light module between the first surface and the second surface and configured to receive light emitted from the plurality of emitters; an edge reflector disposed on a side opposite the light input surface; Equipped with the second surface is inclined such that the height of the light input surface is less than the height of a reflective side opposite the light input surface; Light coupled into the wedge-shaped light redirecting element is reflected by the end reflector and reflected from the second surface towards the first surface. Optical devices. 5. The device of example 1, wherein the optical module comprises at least one wavelength-dependent light redirecting element configured to receive light from the two light emitters. 6. The device of example 1, wherein the optical module comprises at least two wavelength-dependent light redirecting elements configured to receive light from the three light emitters. 7. The device of any of Examples 1-3, wherein the plurality of light emitters comprises at least three emitters. 8. The device of any of Examples 1-4, wherein the at least three emitters comprise a red, a green, and a blue emitter. 9. The device of any of Examples 4-5, wherein the optical module comprises an x-cube having three ports in optical communication with the three emitters. (Example Section VII) 1. An optical device comprising: a first surface parallel to a horizontal axis; a second surface opposite the first surface and inclined relative to the horizontal axis by a wedge angle α; a wedge-shaped light redirecting element comprising: a light module configured to generate light; an optical input surface between the first surface and the second surface, the optical input surface being positioned relative to the optical module and receiving light therefrom, the optical input surface comprising microstructures or nanostructures; an edge reflector disposed on a side opposite the light input surface; the second surface is inclined such that the height of the light input surface is less than the height of the reflective side opposite the light input surface; Light coupled into the wedge-shaped light redirecting element is reflected by the end reflector and reflected from the second surface towards the first surface. Optical devices. 2. The device of example 1, wherein the microstructures or nanostructures are configured to redirect light input through the input surface. 3. The device of any one of examples 1 to 2, wherein the light input surface comprises a diffractive optical element or a diffraction grating. 4. A device according to any of the preceding examples, wherein the optical module is configured to emit a cone of light, the cone of light having an angle of about 10 degrees to 35 degrees from the axis of the cone. 5. The device of any of the preceding examples, further comprising a spatial light modulator positioned relative to the first surface and receiving light reflected from the second surface. (Example Section VIII) 1. A head-mounted display system configured to project light into a user's eye and display augmented reality image content within the user's field of view, comprising: a frame configured to be supported on a user's head; and an eyepiece disposed on the frame, at least a portion of the eyepiece being transparent, the transparent portion being positioned in front of the user's eye when the user wears the head mounted display so as to transmit light from an environment in front of the user to the user's eye to provide a view of the environment in front of the user, the eyepiece comprising one or more waveguides positioned to direct light into the user's eye; a light source configured to emit light; and 1. A polarization sensitive light redirecting element comprising: a first surface parallel to the axis; a second surface opposite the first surface; a light input surface between the first surface and the second surface, the light input surface being configured to receive light emitted from the light source; an edge reflector disposed on a side opposite the light input surface; a polarization sensitive light redirecting element comprising: a second surface of the polarization sensitive light redirecting element such that light coupled into the polarization sensitive light redirecting element is reflected by an end reflector and redirected by the second surface towards the first surface; a spatial light modulator positioned relative to the polarization sensitive light redirecting element to receive and modulate the light emitted from the polarization sensitive light redirecting element; wherein the polarization-sensitive light redirecting element and the spatial light modulator are positioned relative to the eyepiece to direct modulated light into the one or more waveguides of the eyepiece such that the modulated light is directed into a user's eye and forms an image therein. 2. The system of example 1, wherein the polarization-sensitive light redirecting element comprises a polarization-selective element on the second surface, the polarization-selective element configured to redirect light reflected by the end reflector toward the first surface. 3. The system of any one of examples 1 to 2, wherein the polarization selective element comprises a liquid crystal. 4. The system of any of Examples 1-3, wherein the polarization selective element comprises a cholesteric liquid crystal. 5. The system of any of Examples 1-4, wherein the polarization selective element comprises a liquid crystal grating. 6. The system of any of Examples 1-5, wherein the polarization selective element comprises a cholesteric liquid crystal grating. 7. A system described in any of Examples 1-6, wherein the polarization selective element comprises multiple layers of liquid crystals, different liquid crystal layers configured to diffract different wavelengths such that light of different wavelengths is directed toward the first surface. 8. A system described in any of Examples 1-7, wherein the polarization selective element comprises multiple layers of cholesteric liquid crystals, different cholesteric liquid crystal layers configured to diffract different colors such that light of different colors is directed toward the first surface. 9. The system of example 1, wherein the polarization-sensitive light redirecting element comprises a plurality of redirecting features disposed on the second surface, the plurality of redirecting features configured to redirect light reflected by the end reflector toward the first surface. 10. The system of example 9, wherein the plurality of redirecting features comprises polarization-selective elements. 11. The system of example 10, wherein the polarization-selective element comprises a thin film, a dielectric coating, or a wire grid. 12. The system of any of Examples 9 or 10, wherein the plurality of redirecting features are configured to redirect a portion of light received through the light input surface having a first polarization state toward the spatial light modulator. 13. The system of example 12, wherein the polarization-sensitive light redirecting element is configured to transmit a portion of the light reflected from the spatial light modulator having a second polarization state. 14. A system according to any of Examples 10-13, wherein the plurality of turning features comprises prismatic turning features. 15. A system described in any of Examples 10-14, wherein the turning feature comprises first and second portions, the first portion having a reflective coating thereon and the second portion not having the reflective coating. 16. The system of example 15, wherein the first and second portions comprise first and second facets. 17. The system of any of Examples 15-16, wherein the reflective coating may comprise a dielectric reflective coating. 18. The system of any of Examples 15-16, wherein the reflective coating may comprise a polarizing coating. 19. The system of any of Examples 10-17, wherein the turning feature has a curved surface. 20. The system of any of Examples 10-18, wherein the plurality of turning features are shaped to have positive optical power. 21. The system of any of Examples 10-18, wherein the plurality of turning features are shaped to have negative optical power. 22. A system described in any of Examples 10-20, wherein the plurality of turning features have a pitch of 20 to 200 micrometers. 23. The system of any of Examples 1-22, wherein the end reflector comprises a curved reflector. 24. The system of example 23, wherein the end reflector comprises a spherical or parabolic mirror. 25. The system of any of Examples 1-22, wherein the end reflector comprises a reflective holographic structure comprising one or more holograms. 26. The system of any of Examples 1-22, wherein the end reflector is configured to collimate light from the light source and direct the collimated light toward the second surface. 27. A system described in any of Examples 1-26, wherein the spatial light modulator is a reflective spatial light modulator and the polarization-sensitive light redirecting element is configured to transmit light reflected from the spatial light modulator therethrough. 28. The system of any of Examples 1-27, further comprising a light redirecting element disposed over the refractive optical element configured to compensate for refraction otherwise caused by the polarization-sensitive light redirecting element. 29. The system of Example 28, wherein the refractive optical element has a shape that complements the polarization-sensitive light redirecting element so as to reduce bending of light from the second surface of the polarization-sensitive light redirecting element. 30. The system of any of examples 28 or 29, wherein the refractive optical element has a right-angle prism shape. 31. The system of any of Examples 28-30, further comprising a polarization-selective component disposed across the refractive optical element. 32. A system described in any of Examples 28-31, wherein the refractive optical element has a surface opposite the first surface of the polarization-sensitive light redirecting element, and the surface opposite the first surface of the polarization-sensitive light redirecting element has an anti-reflective coating thereon. 33. The system of any of Examples 1-32, wherein the light input surface includes an anti-reflective coating thereon. 34. The system of any of Examples 28-33, wherein the refractive optical element has a surface opposite the end reflector, and the surface opposite the end reflector has an absorbing coating thereon. 35. The system of any of examples 1-34, wherein the first surface is parallel to the second surface. 36. A system described in any of Examples 9-35, wherein a light source is coupled into a polarization-sensitive light redirecting element through the input surface, and the system is positioned relative to the input surface such that light from the source is reflected by an end reflector and redirected by a plurality of redirecting features toward the first surface within an angular range of approximately 10 degrees relative to a normal to the first surface. 37. The system of any of Examples 1-36, wherein the polarization-sensitive light redirecting element comprises a waveguide and light from the light source is totally internally reflected from at least the first surface. 38. The system of any of Examples 1-37, wherein the end reflector is configured to collimate light from the emitter incident thereon. 39. The system of any of Examples 1-38, wherein the input light surface includes turning features thereon to redirect light from the light source. 40. A system described in any of Examples 1-39, wherein the input light surface is orthogonal to the axis. 41. A system according to any of Examples 1-40, wherein the input light surface is tilted perpendicular to the axis. 42. A system described in any of Examples 1-41, wherein the light source has an output surface and an air gap is disposed between at least a portion of the output surface of the light source and the input light surface of the polarization-sensitive light redirecting element. 43. The system of any of Examples 1-42, wherein the light source has an output surface, and at least a portion of the output surface of the light source contacts the input light surface of the polarization-sensitive light redirecting element. 44. The system of any of Examples 1-43, further comprising a polarizer configured to deflect light input from the light source through the input light surface. 45. A system described in any of Examples 1-44, wherein the light source is in optical communication with the input light surface of the polarization-sensitive light redirecting element via an optical fiber. 46. ​​A system described in any of Examples 1-45, wherein the light source comprises at least one of a laser or an LED. 47. The system of any of Examples 1-46, wherein the light source is configured to deliver at least red, green, and blue light through the light input surface into the polarization-sensitive light redirecting element. 48. A system described in any of Examples 1-47, wherein the light source comprises a plurality of emitters or lighting modules configured to output light. 49. A system described in any of Examples 1-48, wherein each of the multiple emitters or lighting modules emits light of a different color. 50. The system of any of Examples 1-49, wherein the different colored lights comprise red light, green light, and blue light. 51. A system described in any of Examples 1-50, wherein the light source comprises two emitters or two lighting modules configured to output light. 52. A system described in any of Examples 1-50, wherein the light source comprises three emitters configured to output light. 53. A system described in any of Examples 1-52, wherein the polarization-sensitive light redirecting element and the one or more waveguides have a length along a direction parallel to the axis, and the length of the polarization-sensitive light redirecting element is less than 1 / 3 of the length of the one or more waveguides. 54. A system described in any of Examples 1-53, wherein the polarization-sensitive light redirecting element has a length along a direction parallel to the axis, the length being less than 10 mm. 55. A system described in any of Examples 1-54, wherein one or more waveguides within the eyepiece lens include one or more internal coupling optical elements, and the polarization-sensitive light redirecting element and spatial light modulator are positioned relative to the one or more internal coupling optical elements and direct light from the spatial light modulator therein. 56. The system of any of Examples 1-55, wherein the second surface is angled such that the height of the light input surface is less than the height of the end reflector opposite the light input surface. 57. The system of any of Examples 1-56, wherein the second surface is inclined relative to the axis by a wedge angle α. 58. The system described in Example 57, wherein the wedge angle α is between about 15 degrees and about 45 degrees. 59. A system described in any of Examples 1-58, wherein the refractive optical element has a wedge shape. (Example Section IX) 1. A lighting system comprising: a light source configured to emit light; and A wedge-shaped light redirecting element, a first surface parallel to the axis; a second surface opposite the first surface and inclined relative to the axis by a wedge angle α; a light input surface between the first surface and the second surface, the light input surface being configured to receive light emitted from the light source; an edge reflector disposed on a side opposite the light input surface; a wedge-shaped light redirecting element, the second surface of which is angled such that the height of the light input surface is less than the height of an end reflector opposite the light input surface, such that light coupled into the wedge-shaped light redirecting element is reflected by the end reflector and redirected by the second surface towards the first surface; a spatial light modulator positioned relative to the wedge-shaped light redirecting element to receive and modulate the light emitted from the wedge-shaped light redirecting element; A lighting system comprising: 2. The illumination system of Example 1, wherein the wedge-shaped light redirecting element comprises a polarization-selective element on a second surface, the polarization-selective element configured to redirect light reflected by the end reflector towards the first surface. 3. The illumination system of any one of examples 1 to 2, wherein the polarization selective element comprises a liquid crystal. 4. The illumination system of any of Examples 1-3, wherein the polarization selective element comprises a cholesteric liquid crystal. 5. The illumination system of any of Examples 1-4, wherein the polarization selective element comprises a liquid crystal grating. 6. The illumination system of any of Examples 1-5, wherein the polarization selective element comprises a cholesteric liquid crystal grating. 7. An illumination system described in any of Examples 1-6, wherein the polarization selective element comprises multiple layers of liquid crystals, different liquid crystal layers configured to diffract different wavelengths such that light of different wavelengths is directed toward the first surface. 8. An illumination system described in any of Examples 1-7, wherein the polarization selective element comprises multiple layers of cholesteric liquid crystals, different cholesteric liquid crystal layers configured to diffract different colors such that light of different colors is directed toward the first surface. 9. The lighting system of Example 1, wherein the wedge-shaped light redirecting element comprises a plurality of redirecting features disposed on the second surface, the plurality of redirecting features configured to redirect light reflected by the end reflector toward the first surface. 10. The illumination system of example 9, wherein the plurality of redirecting features comprises polarization-selective elements. 11. The illumination system of example 10, wherein the polarization-selective element comprises a thin film, a dielectric coating, or a wire grid. 12. An illumination system as described in any of Examples 9 or 10, wherein the plurality of redirecting features are configured to redirect a portion of light received through the light input surface having a first polarization state toward the spatial light modulator. 13. The illumination system of example 12, wherein the wedge-shaped light redirecting element is configured to transmit a portion of the light reflected from the spatial light modulator having the second polarization state. 14. The lighting system of any of Examples 10-13, wherein the plurality of turning features comprises prismatic turning features. 15. An illumination system described in any of Examples 10-14, wherein the turning feature comprises first and second portions, the first portion having a reflective coating thereon and the second portion not having the reflective coating. 16. The illumination system of example 15, wherein the first and second portions comprise first and second facets. 17. The illumination system of any of Examples 15-16, wherein the reflective coating may ...

Claims

1. 1. An optical device comprising: a spatial light modulator; Light redirecting elements and wherein the light redirecting element comprises: A waveguide, a first surface; and a second surface opposite the first surface; and a plurality of polarization-selective light redirecting features directly above the second surface; an optical input surface between the first surface and the second surface, the optical input surface being arranged to receive light emitted from a light source and couple the light into the waveguide; a waveguide including an end reflector proximate the side of the light redirecting element opposite the light input surface; a compensation layer disposed on the second surface; and the plurality of polarization-selective light redirecting features are configured to i) redirect a first portion of the light having a first polarization state towards the first surface and the spatial light modulator, and ii) not redirect a second portion of the light having a second polarization state different from the first polarization state; at least a portion of the light coupled into the waveguide is reflected by the end reflector and redirected by the plurality of polarization-selective light redirecting features toward the first surface and the spatial light modulator; the plurality of polarization-selective light redirecting features are configured to transmit through the second surface a portion of the light reflected from the spatial light modulator having a second polarization state different from the first polarization state; the spatial light modulator modulates the light redirected by the plurality of polarization-selective light redirecting features and reflects the modulated light through the waveguide; The optical device, wherein the compensation layer is configured to reduce refraction of the modulated light by the second surface as the modulated light passes through the waveguide.

2. 10. The optical device of claim 1, wherein the end reflector comprises a mirror configured to redirect light received through the light input surface along a direction substantially parallel to the first surface, the mirror being a spherical mirror or a parabolic mirror.

3. The optical device of claim 1 , wherein the end reflector comprises a reflective holographic structure comprising one or more holograms.

4. The optical device of claim 1 , wherein the end reflector is configured to collimate the light incident on the end reflector.

5. 1. An optical device comprising: a spatial light modulator; Light redirecting elements and wherein the light redirecting element comprises: A waveguide, a first surface; and a second surface opposite the first surface; and a plurality of polarization-selective light redirecting features directly above the second surface; an optical input surface between the first surface and the second surface, the optical input surface being arranged to receive light emitted from a light source and couple the light into the waveguide; a waveguide including an end reflector proximate the side of the light redirecting element opposite the light input surface; and the plurality of polarization-selective light redirecting features are configured to i) redirect a first portion of the light having a first polarization state towards the first surface and the spatial light modulator, and ii) not redirect a second portion of the light having a second polarization state different from the first polarization state; at least a portion of the light coupled into the waveguide is reflected by the end reflector and redirected by the plurality of polarization-selective light redirecting features toward the first surface and the spatial light modulator; 10. The optical device of claim 1, wherein the light redirecting element is a wedge-shaped light redirecting element, and the second surface is tilted relative to the first surface by a wedge angle such that a height of the light input surface is less than a height of an opposite side of the light input surface.

6. The optical device of claim 5 , wherein the wedge angle is between about 15 degrees and about 45 degrees.

7. The optical device of claim 5 further comprising a refractive optical element disposed above the light redirecting element.

8. The optical device of claim 7 further comprising a polarization-selective component disposed above the refractive optical element.

9. 10. The optical device of claim 1, further comprising a light source arranged with respect to the light input surface such that the light from the light source coupled into the waveguide is reflected by the end reflector and redirected by the plurality of polarization-selective light redirecting features towards the first surface in an angular range of between approximately −10 degrees and +10 degrees relative to a normal to the first surface.

10. The optical device of claim 1 further comprising a quarter-wave retarder arranged between the end reflector and a side of the waveguide opposite the light input surface.

11. 11. The optical device of claim 10, wherein the quarter-wave retarder is transmissive such that the light incident on the quarter-wave retarder is transmitted to the end reflector.

12. 12. The optical device of claim 11, wherein the quarter-wave retarder is configured to convert at least a portion of the light incident on the quarter-wave retarder and having the second polarization state to the first polarization state.

13. 2. The optical device of claim 1, wherein the first polarization state is an s-polarization state and the second polarization state is a p-polarization state.

14. The optical device of claim 1 , wherein the plurality of polarization-selective light-redirecting features comprise a diffraction grating.

15. The optical device of claim 1 , wherein each of the plurality of polarization-selective light-redirecting features is a holographic optical element.

16. The optical device of claim 1 , wherein each of the plurality of polarization-selective light-redirecting features is a nanostructure or a microstructure.

17. The optical device of claim 1, further comprising a reflective element positioned opposite the end reflector, the reflective element configured to reflect at least some of the light transmitted through the second surface back into the waveguide.

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