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 technologies have facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally reproduced images or portions thereof are presented to a user in a manner that appears or may be perceived as real. Virtual reality or "VR" scenarios typically involve the presentation of digital or virtual image information without transparency to other actual real-world visual inputs, while augmented reality or "AR" scenarios typically involve the presentation of digital or virtual image information as an extension to the visualization of the real world around the user. Mixed reality or "MR" scenarios are a type of AR scenario that typically involve virtual objects that are integrated into and responsive to the natural world. For example, MR scenarios may include AR image content that appears blocked by or is otherwise perceived to 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, buildings 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 as a result, 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 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 to 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 disposed in a location in front of the user's eye when the user wears the head mounted display such that the transparent portion transmits 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 may include one or more waveguides disposed 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 a plurality of light emitters. The optical module may be configured to combine light for the plurality of emitters. The optical device may further include an optical input surface disposed relative to the optical module between the first surface and the second surface and receiving light emitted from the plurality of emitters. The optical device may include an end reflector disposed on a side opposite the optical input surface. The second surface may be tilted such that the height of the optical input surface is less than the height of the side opposite the optical input surface. Light coupled into the wedge-shaped light redirecting element may be reflected by the end reflector and / or reflected from the second surface towards 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 disposed 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 surface and the second surface and configured to receive light emitted from the light source. The polarization sensitive light redirecting element may further include an end reflector disposed 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 disposed relative to the polarization sensitive light redirecting element to receive light emitted from the polarization sensitive light redirecting element and modulate the light. [Brief description of the drawings]

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

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

[0015] [Diagram 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] [Diagram 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 an example of multiple stacked waveguides 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 shown in FIG. 12A, according to some embodiments.

[0028] [Figure 13A] FIG. 13A illustrates a method of manufacturing 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 manufacturing a polarization sensitive reflector manufactured as shown in FIG. 13A, according to some embodiments.

[0031] [Figure 13D] FIG. 13D illustrates a polarization sensitive reflector manufactured using the methods 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 example configurations of illumination modules in conjunction with polarizing beam splitters, according to some embodiments. [Figure 17-2] 17A-17H illustrate various example configurations of illumination modules in conjunction with polarizing beam splitters, according to some embodiments.

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

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

[0039] [Figure 18-4] 18Q-18V illustrate various example 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 example light pipe integrator including a color source area according to some embodiments.

[0042] [Figure 20B] FIG. 20B shows an example 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 combination 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 an 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 example reflective lighting module of FIG. 22A, according to some embodiments.

[0049] [Figure 22C] FIG. 22C illustrates 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 a first color cell in an off state according to some embodiments.

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

[0053] [Figure 23D] FIG. 23D shows a third color cell in an off state 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] [Diagram 25] FIG. 25 illustrates a perspective view of another example lighting system, according to some embodiments.

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

[0058] [Figure 27] 27 diagrammatically illustrates an illumination system configured to provide illumination to a spatial light modulator associated with various embodiments of a 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 redirection 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 redirection 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 redirection 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 redirection 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 refractive power, according to some embodiments.

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

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

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

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

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

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

[0071] [Diagram 36] FIG. 36 illustrates an example of a display device incorporating 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 PREFERRED EMBODIMENTS

[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] A display system may employ a spatial light modulator that modulates the polarization state of light in some cases. Such a spatial light modulator may include, for example, a liquid crystal spatial light modulator, such as liquid crystal on silicon (LCOS). Such a spatial light modulator 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 linear polarization of a first orientation (e.g., s-polarized). 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 having a linear polarization of a first orientation (s-polarized) to produce linear polarization of a second orientation (e.g., p-polarized). A polarizer or analyzer may be used to filter out the light of one of the polarization states, thereby converting the polarization modulation into an intensity modulation that may 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 a spatial light modulator 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, in which like reference numbers 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 in front of the user's 90 eye. 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 ear canal of the user 90 (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 may be configured to allow the 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 the 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 or belt-type configuration). Similarly, the sensor 120a may be operably coupled to the local data processing module 140 by a communication link 120b, such as wired or wireless connectivity. The local processing and data module 140 may include a hardware processor and digital memory, such as non-volatile memory (e.g., flash memory or hard disk drive), both of which may be utilized to aid in processing, caching, and storing data. The data includes a) captured 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 the frame 80 or otherwise attached to the user 90, for example) and / or b) data obtained and / or processed using a remote processing module 150 and / or a remote data repository 160 (including data related to the virtual content), possibly for passing to the display 70 after processing or retrieval. The local processing and data module 140 may be operatively coupled to the remote processing module 150 and the remote data repository 160 by communications 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 the 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 free-standing 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 digital data storage facilities that may be available through the Internet or other networking configurations in a "cloud" resource configuration. In some embodiments, remote data repository 160 may include one or more remote servers that provide information, such as 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 calculations are performed within the local processing and data module, allowing for fully autonomous use from the remote modules.

[0082] Referring now to FIG. 3, the perception of an image as "three-dimensional" or "3-D" may be achieved by providing a slightly different presentation of the image to each eye of 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 apart from the eyes 210, 220 by a distance 230 along an optical or z-axis parallel to the viewer's line of sight. The images 190, 200 are flat and the eyes 210, 220 may focus on the images by assuming a single accommodated state. Such a 3-D display system relies on the human visual system to combine the images 190, 200 and provide a perception of depth and / or scale of the combined image.

[0083] However, it should be appreciated that the human visual system is more complex and more difficult to provide a realistic perception of depth. For example, many viewers of conventional "3-D" display systems may find such systems uncomfortable or may not perceive any sense of depth at all. Without being limited by theory, it is believed that a viewer of an object may perceive the object as "three-dimensional" due to a combination of vergence and accommodation. The vergence movement of the two eyes relative to each other (e.g., eye rotation, where 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 lenses and pupils. Under normal conditions, changing the focus of the eye's lens or accommodating the eye from one object to another at different distances will automatically produce a matching change in vergence to the same distance, under a relationship known as the "accommodation-vergence reflex" and pupil dilation or constriction. Similarly, a change in vergence will induce a matching change in accommodation of lens shape and pupil size under normal conditions. As described herein, many stereoscopic or "3-D" display systems display a scene using a slightly different presentation (and therefore a slightly different image) to each eye such that a three-dimensional perspective is perceived by the human visual system. However, such systems are uncomfortable for many viewers because, among other things, they simply provide a different presentation of the scene, but work against the "accommodation-vergence reflex" when the eyes view the entire image information in a single accommodated state. Display systems that provide better matching between accommodation and vergence may produce a more realistic and comfortable simulation of a three-dimensional image.

[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 such 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 part of an object at a particular depth plane is in focus when the eye is in an 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. Although 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, while shown as flat for ease of illustration, it should be understood that the contour of the depth plane may be curved in physical space such that all features within the depth plane are in focus with the eye in a particular accommodated state.

[0085] The distance between an object and the eye 210 or 220 may also change the amount of divergence of light from that 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 in the order of decreasing distances R1, R2, and R3. As shown in Figures 5A-5C, the light rays become more divergent as the distance to the object decreases. As the distance increases, the light rays become more collimated. In other words, the light field generated by a point (an object or part of an object) may be said to have a spherical wavefront curvature that is a function of the distance the point is away from the user's eye. The curvature increases with decreasing distance between the object and the eye 210. As a result, at different depth planes, the divergence of the light rays is also different, and the divergence increases with decreasing distance between the depth plane and the viewer's eye 210. Although only a monocular 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 may be achieved by providing the eye with different presentations of images corresponding to each of these limited number of depth planes. The different presentations may be focused separately by the viewer's eye, 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. The display system 250 includes a stack of waveguides or a 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, the display system 250 is the system 60 of FIG. 2, of which FIG. 6 illustrates several portions in more detail. For example, the waveguide assembly 260 may be part of the display 70 of FIG. 2. It should be understood that the display system 250 may be considered a light field display in some embodiments. In addition, the 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 a number of 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 the number of lenses 320, 330, 340, 350 may be configured to transmit image information to the eye with various levels of wavefront curvature or light beam divergence. Each waveguide level may be associated with a particular depth plane and may be configured to output image information corresponding to that depth plane. The image input devices 360, 370, 380, 390, 400 may act as light sources for the waveguides and may be utilized to input image information into the waveguides 270, 280, 290, 300, 310, each of which may be configured to disperse incident light across each individual waveguide for output towards the eye 210, as described herein. Light exits output surfaces 410, 420, 430, 440, 450 of the image input devices 360, 370, 380, 390, 400 and is input into corresponding input surfaces 460, 470, 480, 490, 500 of the waveguides 270, 280, 290, 300, 310. In some embodiments, each of the input surfaces 460, 470, 480, 490, 500 may be an edge of the corresponding waveguide or may be a portion of the 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 towards 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 the respective waveguides 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 to each of the image input devices 360, 370, 380, 390, 400 via one or more optical conduits (such as fiber optic cables). 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, the 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). The 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 change 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 that are 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 is to be understood that one or more optical fibers may be configured to transmit light from the optical module 540 to one or more of the waveguides 270, 280, 290, 300, 310. It is to be understood that one or more intervening optical structures may be provided between the scanning fiber or fibers and one or more of the waveguides 270, 280, 290, 300, 310, for example, to redirect light exiting the scanning fiber into one or more of the waveguides 270, 280, 290, 300, 310.

[0092] The controller 560 controls the operation of one or more of the stacked waveguide assemblies 260, including the operation of the image input devices 360, 370, 380, 390, 400, the light source 540, and the light modulator 530. In some embodiments, the controller 560 is part of the local data processing module 140. The controller 560 includes programming (e.g., instructions in a non-transient medium) that coordinates the timing and provisioning of image information to the 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. The controller 560 may be part of the processing module 140 or 150 (FIG. 2) in some embodiments.

[0093] Continuing with reference to FIG. 6, the waveguides 270, 280, 290, 300, 310 may be configured to propagate light within each individual waveguide by total internal reflection (TIR). Each of the waveguides 270, 280, 290, 300, 310 may be planar or have another shape (e.g., curved) with major top and bottom surfaces and edges extending between their major top and bottom surfaces. In the illustrated configuration, the waveguides 270, 280, 290, 300, 310 may each include an out-coupling optical element 570, 580, 590, 600, 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 out-coupled light, and the out-coupling optical element may also be referred to as a light extraction optical element. The extracted beam of light may be output by the waveguide at a location where the 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 further discussed herein. Although shown disposed on the bottom major surface of the waveguide 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 waveguide 270, 280, 290, 300, 310, as further discussed 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 waveguide 270, 280, 290, 300, 310. In some other embodiments, the waveguide 270, 280, 290, 300, 310 may be a monolithic piece 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] With continued 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 it can reach the eye 210. Such first lens 350 may be configured to generate a slight convex wavefront curvature such that the eye / brain interprets the light originating from the next upper waveguide 280 as originating from a first focal plane 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 incremental amount of wavefront curvature such that the eye / brain interprets the light originating from the third waveguide 290 as originating from a second focal plane 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 an aggregate focal power that represents the focal plane closest to the person. To compensate 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 aggregate power of the lens stacks 320, 330, 340, 350 below. Such a configuration provides as many perceived focal planes as there are waveguide / lens pairs available. Both the outcoupling optical elements of the waveguides and the focusing sides of the lenses may be static (i.e., not dynamic or electroactive). In some alternative embodiments, one or both may be dynamic using electroactive features.

[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 the 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 the waveguide. As a result, waveguides with different associated depth planes may have different configurations of outcoupling optical elements 570, 580, 590, 600, 610 that 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 that 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 such that only a portion of the light in the beam is deflected towards the eye 210 with each intersection point of the DOE, while the remainder continues to travel through the waveguide via TIR. The light carrying the image information is thus split into several related exit beams that exit the waveguide at various locations, resulting in a very uniform pattern of exit emission towards 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 a physiological condition 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 to the frame 80 (FIG. 2) and may be in electrical communication with the 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. Although one waveguide is shown, it should be understood that other waveguides in the waveguide assembly 260 (FIG. 6) may function similarly and that the waveguide assembly 260 includes multiple waveguides. Light 640 is launched into the waveguide 270 at the input surface 460 of the waveguide 270 and propagates within the waveguide 270 by TIR. At the point where the light 640 impinges on the DOE 570, a portion of the light exits the waveguide as an output beam 650. The output beam 650 is shown as approximately parallel, but may be redirected to propagate to the eye 210 at an angle (e.g., forming a diverging output beam) as discussed herein and depending on the depth plane associated with the 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 an exit beam pattern that is more divergent, 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 on each of the primary colors, for example, three or more primary colors. FIG. 8 illustrates an example of a stacked waveguide assembly, where each depth plane includes an image formed using multiple different primary colors. The illustrated embodiment shows depth planes 240a-240f, but more or less depths are also contemplated. Each depth plane may have three or more primary color images associated with it, including a first image of a first color G, a second image of a second color R, and a third image of a third color B. The different depth planes are indicated in the diagram by different numbers for diopters (dpt) following the letters G, R, and B. Merely by way of example, the numbers following each of these letters indicate the diopters (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 the 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 that correspond to different distances from the user. Such an arrangement may increase visual acuity and user comfort, and / or reduce chromatic aberration.

[0103] In some embodiments, the light of 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 figure containing the letter G, R, or B may be understood to represent an individual waveguide, and three waveguides may be provided per depth plane, with three primary color images provided per depth plane. The waveguides associated with each depth plane are shown adjacent to each other in this drawing for ease of illustration, but 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 in place of one or more of the red, green, or blue colors.

[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, the light source 540 (FIG. 6) may be configured to emit light at one or more wavelengths outside the range of visual perception of a viewer, e.g., infrared and / or ultraviolet wavelengths. Additionally, the waveguide in-coupling, out-coupling, and other light redirecting structures of the 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] 9A, in some embodiments, light impinging on a waveguide may need to be redirected to in-couple the light into the waveguide. An in-coupling optical element may be used to redirect and in-couple 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 in-coupling optical element. Each of the waveguides may be configured to output light of one or more different wavelengths or one or more different wavelength ranges. The stack 660 may correspond to the stack 260 (FIG. 6), and the illustrated waveguides of the stack 660 may correspond to a portion of the plurality of waveguides 270, 280, 290, 300, 310, but it should be understood that light from one or more of the image input devices 360, 370, 380, 390, 400 is launched into the waveguide from a position that requires the light to be redirected for in-coupling.

[0108] The illustrated set 660 of stacked waveguides includes waveguides 670, 680, and 690. Each waveguide includes an associated incoupling optical element (which may also be referred to as the light input area on the waveguide), for example, incoupling optical element 700 is disposed on a major surface (e.g., the top major surface) of waveguide 670, incoupling optical element 710 is disposed on a major surface (e.g., the top major surface) of waveguide 680, and incoupling 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 the incoupling optical elements 700, 710, 720 may be disposed on a bottom major surface of an individual waveguide 670, 680, 690 (particularly, one or more of the incoupling optical elements are reflective polarizing optical elements). As shown, the incoupling 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 incoupling optical elements are transmissive deflecting optical elements. In some embodiments, the incoupling 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 incoupling optical elements 700, 710, 720 are wavelength selective such that they selectively redirect one or more wavelengths of light while transmitting other wavelengths of light. Although illustrated on one side or corner of the respective waveguide 670, 680, 690, it should be understood that the incoupling 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 not substantially receive 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., a top major surface) of waveguide 670, optically dispersive element 740 is disposed on a major surface (e.g., a top major surface) of waveguide 680, and optically dispersive element 750 is disposed on a major surface (e.g., a 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] The waveguides 670, 680, 690 may be spaced apart and separated by, for example, gas, liquid, and / or solid layers of material. For example, as shown, layer 760a may separate the waveguides 670 and 680, and layer 760b may separate the waveguides 680 and 690. In some embodiments, layers 760a and 760b are formed from a low index material (i.e., a material having a lower index of refraction than the material forming the immediate neighbors of the waveguides 670, 680, 690). Preferably, the index of refraction of the material forming layers 760a, 760b is 0.05 or more, or 0.10 or less, than the index of refraction of the material forming the waveguides 670, 680, 690. Advantageously, the lower refractive index layers 760a, 760b may act as cladding layers to 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 the waveguides 670, 680, 690 are similar or the same, and the materials forming the layers 760a, 760b are similar or the same. In some embodiments, the materials forming the waveguides 670, 680, 690 may differ between one or more of the waveguides, and / or the materials forming the layers 760a, 760b may differ while still maintaining the various refractive index relationships discussed above.

[0113] 9A, light rays 770, 780, 790 are incident on 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, the light beams 770, 780, 790 have different properties, e.g., different wavelengths or different wavelength ranges, that may correspond to different colors. Each of the incoupling optical elements 700, 710, 720 deflects the 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, incoupling optical element 700 may be configured to selectively deflect light beam 770 having a first wavelength or wavelength range while transmitting light beams 780 and 790 having different second and third wavelengths or wavelength ranges, respectively. Transmitted light beam 780 impinges on and is deflected by incoupling optical element 710, which is configured to selectively deflect light of the second wavelength or wavelength range. Light beam 790 is deflected by incoupling 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 incoupling optical element 700, 710, 720 of each waveguide deflects the light into its corresponding waveguide 670, 680, 690 and incouplings 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 corresponding optical dispersive element 730, 740, 750 of the waveguide.

[0117] 9B, a perspective view of the multiple stacked waveguide embodiment of FIG. 9A is illustrated. As previously described, the in-coupled light rays 770, 780, 790 are deflected by the in-coupling optical elements 700, 710, 720, respectively, and then propagate by TIR within the waveguides 670, 680, 690, respectively. The light rays 770, 780, 790 then impinge on the optically dispersive elements 730, 740, 750, respectively. The optically dispersive elements 730, 740, 750 deflect the light rays 770, 780, 790 to propagate towards the 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 the light to 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 to 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 the light directly to the out-coupling optical elements 800, 810, 820. For example, referring 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 to the viewer's eye 210 (FIG. 7). It should be understood that the OPEs may be configured to increase the size of the eyebox in at least one axis, and the EPEs may increase the eyebox in an axis that intersects, 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. In response to striking the OPE, again, another portion of the remaining light is redirected to the EPE, which continues to propagate further down the waveguide, etc. Similarly, in response to striking the EPE, a portion of the striking light is directed out of the waveguide towards the user, and the remaining portion of the light continues to propagate through the waveguide until it strikes the EP again, at which point another portion of the striking 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] Thus, referring to Figures 9A and 9B, in some embodiments, a set of waveguides 660 includes, for each primary color, a waveguide 670, 680, 690, an in-coupling optical element 700, 710, 720, an optical dispersion element (e.g., OPE) 730, 740, 750, and an out-coupling optical element (e.g., EP) 800, 810, 820. The waveguides 670, 680, 690 may be stacked with an air gap / cladding layer between each one. The in-coupling optical element 700, 710, 720 redirects or deflects the incoming light into its waveguide (with different in-coupling optical elements receiving different wavelengths of light). The light then propagates at an angle that will result in TIR within the individual waveguides 670, 680, 690. In the illustrated embodiment, light ray 770 (e.g., blue light) is deflected by the first in-coupling optical element 700 in the manner described above, then continues to bounce back 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, where light ray 780 impinges on and is deflected by the in-coupling optical element 710. Light ray 780 will then proceed via TIR back 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 beam 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 beam 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, the waveguides 670, 680, 690 may be vertically aligned with each waveguide's associated light dispersive element 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, an arrangement including non-overlapping spatially separated in-coupling optical elements may be referred to as a shifted pupil system, and the in-coupling optical elements in these arrangements may correspond to sub-pupils. Illumination system for optical projection system - Patents.com

[0121] 10 diagrammatically 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., s-polarization state) from the illumination module 102 towards the SLM 106 and transmit light modulated by the SLM 106 having a second polarization state (e.g., p-polarization state) towards a viewer. Transmitting the light towards the viewer may include, for example, transmitting the light towards one or more waveguides (e.g., waveguide stacks). 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 about 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) 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) 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) between about 2.0 mm and about 6.0 mm, between about 3.0 mm and about 5.0 mm, between about 3.5 mm and 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 transmissive 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 is in contact with the polarization-sensitive reflector 116. In the implementation illustrated in FIG. 10, where 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 that is coated with a reflective material (e.g., a metal or a dielectric). The end reflector 114 may include one or more dielectric layers, such as a multi-layer 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 a 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 (converging point) or a virtual focal point, for example, in a region 1344 away from the light source 102, as depicted in, for example, FIGS. 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 the light source 102. In such an embodiment, a redirecting feature (e.g., redirecting feature 1314) may be configured to provide a refractive power and redirect the light reflected from the end reflector 114 toward the spatial light modulator 106. The redirecting features 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 such 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 such that light reflected from the end reflector 114 is substantially collimated and / or 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 may extend along an axis parallel to the x-axis. The second surface 113B can be tilted or inclined 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 inclined or inclined towards the light input surface 113C. The inclination 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 inclination 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 a sub-range within any range formed by any of these ranges / 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 of the light output from the lighting module 102 and emitted within the 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 about 41 degrees relative to the optical axis of the LED (which can be aligned parallel to the x-axis). In such an embodiment, the tilt angle "α" of the second surface 113B can be about 20 degrees to about 30 degrees with respect to a horizontal axis parallel to the x-axis or with respect to the first surface 113A or the SLM 106 or a front surface thereof such 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 less 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 across the second surface 113B of the waveguide 112. The polarization sensitive reflector 116 redirects the light reflected from the end reflector 114 towards 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., 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., p-polarized state) is transmitted. The modulated light from the SLM 106 includes light having the second polarization state (e.g., 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 includes a transparent material, such as a dielectric material (such as 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 counter 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 includes a transparent material, may have a similar index of refraction as waveguide 112 to reduce refraction at second surface 113B of waveguide 112. One or both may include glass and / or plastic in some examples.

[0134] In some embodiments, the 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, the refractive optical element 118 can remove unmodulated light that is unintentionally transmitted through the 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 towards 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 towards 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 in the eyepiece.

[0138] The SLM 106 applies spatial modulation to the signal to provide an image. In the on state, the SLM 106 modulates the input light from a first polarization state (e.g., an s-polarized state) to a second polarization state (e.g., a p-polarized state) such 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, the 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 thus a dark state (e.g., a black pixel) is indicated. In the off state, the light having the first polarization state is reflected by the polarization sensitive reflector 116, reflected within the waveguide 112, and / or becomes the input light to the SLM 106. In the intermediate state, the 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 the polarization-sensitive reflector 116 and a portion of the light having an elliptical polarization state (e.g., a p-polarization state) is reflected by the polarization-sensitive reflector 116.

[0139] FIG. 11 illustrates ray traces associated with the illumination system illustrated in FIG. 10, according to some embodiments. The illumination module 102 may be configured to output and direct the 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 by 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 and collimated light 128 may impinge on the second surface 113B. The second surface 113B may be configured to selectively reflect light (e.g., light in a first polarization state) and redirect the light towards the SLM 106. The redirected light 130 may propagate towards the SLM 106, which may be configured to selectively modulate and reflect the redirected light 130. In some embodiments, for example as shown, the 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 may propagate through the PBS 104, the waveguide 112, and / or the refractive optical element 118, and thus may 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 the first polarization state to the second polarization state may be accomplished in a number of 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 (e.g., an "on" state) for modulating light. Other configurations are also possible. The transmitted light 132 may be in a polarization state (eg, 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 manufacturing 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 a transparent material. The transparent material may be, for example, glass, plastic, or other optically transparent material. Different layers, e.g., each layer (e.g., any one of layers 702A-702L) in the stack 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, e.g., each layer 702A-702L of layers 702A-702L, may 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, e.g., 5° 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 to, and / or attached to the waveguide 112. For example, the polarization sensitive reflector 716 is disposed over, molded to, and / or attached to the second surface 113B of the waveguide 112. The reflective optical element 118 is disposed over, molded to, and / or attached to the polarization sensitive reflector 716.

[0145] FIG. 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 spaced 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 to no polarization-selective coating). A plurality of 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 that does not have a polarization-sensitive element will pass through that portion of the polarization-sensitive reflector 716 until it is incident on a section that has 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 section of a different layer that includes polarization sensitive elements that reflect polarized light, as shown.

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

[0147] The polarization sensitive reflector 716 may be disposed 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 is less than 25°. o ~65 oIn some embodiments, for example as illustrated in FIG. 13D, the sum of the angles may be 45° for light reflected from an end reflector 114 that is 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 cholesteric liquid crystal (CLC) elements, such as CLC gratings, 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 a cholesteric liquid crystal element, including 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, for example, 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. In addition, 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 a specific polarization state. 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, the cholesteric liquid crystal reflective element 816. However, light not within that wavelength range and not in that polarization state may be passed through the cholesteric liquid crystal reflective element.

[0150] FIG. 14B illustrates a cholesteric liquid crystal element 816 that includes a stack of cholesteric liquid crystal layers 824, 826, 828. Different layers 824, 826, 828 in the stack may include cholesteric liquid crystal gratings configured for a particular wavelength or range 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 particular 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 particular 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 particular polarization state. Light of a different color than the corresponding cholesteric liquid crystal layer 824, 826, 828 is configured to reflect may pass through the corresponding layer until it reaches the layer 824, 826, 828, which is configured to reflect light of that color, for example. The use of multiple layers that act on different colors allows multiple wavelengths to be redirected and illuminate the SLM 106 .

[0151] FIG. 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 orthogonally polarized (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 metal and / or dielectric materials and, in some implementations, may be a multi-layer coating. The reflective coating 604 may, in some implementations, be configured to reflect greater than 90%, 95%, or 99% of the light (e.g., visible light) that is 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] An anti-reflective coating 608 may be disposed on the refractive optical element 118, for example, on the surface opposite the polarization sensitive reflector 116 and / or opposite the first surface 113A of the waveguide 112 and / or opposite the anti-reflective coating 606. The anti-reflective coating 608 may increase the exit efficiency of the modulated light from the PBS 104 and reduce back-reflection onto the SLM 106, thus increasing the efficiency of operation of the PBS 104.

[0155] The anti-reflective 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 anti-reflective 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 a particular design wavelength, for example. In some designs, the anti-reflective coatings 606, 607, 608 may include a multi-layer coating and include at least two coating layers. The anti-reflective coating may include an interference coating. One or more of the anti-reflective coatings 606, 607, 608 may be a broadband anti-reflective coating.

[0156] Light reflected from the end reflector 114 may first propagate towards 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 having 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 a 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 a 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. A blackening coating 615 may be disposed on the surface 614 perpendicular to the second surface 113B of the refractive optical element 118 in some implementations. 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 disposed 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, the waveguide 112 is wedge-shaped with the second surface 113B angled relative to the light input surface 113C. The wedge angle 502 describes the inclination of the second surface 113B relative to the first surface 113A. Although the wedge is often triangular, the wedge-shaped waveguide 112 may be truncated to create a light input surface 113C that may be used to input light into the waveguide 112. Thus, in this example, the intersection of the plane defined by the two surfaces may occur outside the PBS 104, for example, as shown in FIG. 16. Other configurations are possible. In some embodiments, the wedge angle 502 is an acute angle. For example, the wedge angle 502 may be about 5°. o ~55 o In some embodiments, the wedge angle 502 is about 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 adjacent 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, or ⅜ times smaller, than 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 lighting module 102 in relation to the PBS 104, according to some embodiments. For example, FIGS. 17A-17H illustrate various configurations and / or orientations of the lighting module 102 in relation to the light input surface 113C and variations of the configurations and / or orientations of the light input surface 113C. The lighting module 102 may have a central optical axis that may be perpendicular to the output surface of the lighting 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 lighting module 102 is parallel to the surface axis of the light input surface 113C. The output face of the lighting module 102 may be butt-coupled to the light input surface 113C as shown. In some embodiments as 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 the light input surface 113C is perpendicular to a surface (e.g., the surface opposite the refractive optical element 118 and / or the output area and / or the first surface 113A) of the waveguide 112. In some embodiments, the surface axis of the light input surface 113C is not parallel to any surface of the 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, the light input surface 113C forms a right 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 illustrated, for example, in FIG. 17A. Also, in both FIGS. 17B and 17C, the light input surface 113C is tilted with respect to the illumination module 102. Similarly, the surface axis of the illumination module 102 may not be parallel to the normal to the light input surface 113C. As a result of the tilt, an air gap is disposed between the light input surface 113C and the illumination module 102. Also, 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 illustrated, the illumination module 102 launches light into a 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 a 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 a 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 embodiment on an inclined surface opposite the first surface 113A at the narrowest part of the wedge or the apex of the wedge. Thus, the deflecting element 954 is inclined and forms an acute angle with the inclined surface on which the deflecting element 954 is disposed with respect to 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 towards 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 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. FIG. 17F illustrates how 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 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, for example, toward the end reflector 114 using the deflecting element 954. 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 embodiment, on a sloped surface at the narrowest part of the wedge or at the apex of the wedge. Thus, the deflecting element 954 is sloped and forms an obtuse angle with the sloped surface on which the deflecting element is disposed with respect to the first surface 113A of the waveguide 112. The turning element 954 may direct the light, be curved, and / or have optical power, and may propagate toward the end reflector 114, which may collimate the light. The turning element 954 may include an interference coating and / or a dielectric coating, such as metallization. Such coatings may provide, for example, reflection.

[0163] FIG. 17H illustrates a PBS 104 with an input redirecting feature 956 configured to redirect light introduced into the waveguide 112. The redirecting feature 956 is disposed on a surface opposite the end reflector 114. The redirecting 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 redirecting feature 956 toward the end reflector 114 and is redirected and possibly bent by refraction and / or diffraction. The redirecting feature 956 may potentially include micro- and / or nano-prism structures (e.g., gratings). In some implementations, the redirecting 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, the 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 the turning feature 956 intersect the 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 in 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 a first color of light (e.g., red), the second light emitter 1002b may be configured to emit a second color of light (e.g., green), and the third light emitter 1002c may be configured to emit a third color of light (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, 1002c may include one or more LEDs. For example, each light emitter may be exactly one LED or more. However, other configurations (e.g., using a laser) may be used. In some cases, it may be advantageous for one or more of the light emitters 1002a, 1002b, 1002c to emit coherent light. For example, one or more of the light emitters 1002a, 1002b, 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 in a 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, the 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 the 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 the waveguide 112) opposite the end reflector (e.g., end reflector 114). The light from the three emitters 1002a, 1002b, 1002c, which is combined by the color mixing element 1004, is thus launched into the waveguide 112 and propagates towards the end reflector 114.

[0166] 18B shows a first light emitter 1002a injecting light into a first color mixing element 1004a, and a second and third light emitters 1002b, 1002c injecting 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 also 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). The 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 towards 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.Each of the color mixing elements 1004a, 1004b may 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) a certain wavelength of light and / or transmit a different wavelength of light. 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 a lighting 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 injecting light into the first color mixing element 1004a, and second and third light emitters 1002b, 1002c injecting 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 element 1004a, 1004b. The 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 towards the end reflector 114. The lighting module 102 shown in FIG. 18C may include a diffuser 1008. In some embodiments, the emitters 1002a, 1002b, 1002c may be configured to create overlapping, possibly diverging, footprints of light (e.g., R, G, B) 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 positioned 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 a spatial area. In some embodiments, for example, the diffuser 1008 may reduce the likelihood of "hot spots" including observable intensity peaks. The diffuser 1008 may also help mix together the light of the different light emitters 1002a, 1002b, 1002c in the waveguide 112, which receives light from the lighting module 102, for example. In some embodiments, the diffuser 1008 may also diverge the beam incident thereon. The diffuser 1008 may thus provide an emission cone useful for a head-mounted display system that may be in optical communication with it.

[0168] FIG. 18D shows a similar design to FIG. 18C, including 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, 1012c may be collimating lenses configured to collimate light from the corresponding emitters 1002a, 1002b, 1002c, for example. The lenses 1012a, 1012b, 1012c may form collimated beams from light emitted by the light emitters 1002a, 1002b, 1002c, for example, which may overlap in the color mixing elements 1004a, 1004b and / or dichroic beam combiners and / or diffusers, respectively. In some embodiments, the lenses 1012a, 1012b, 1012c may have negative refractive power. In some embodiments, the refractive power and position of the lenses 1012a, 1012b, 1012c may be configured to create a diverging light cone entering the waveguide 112, for example. The lenses 1012a, 1012b, 1012c can help control the amount of divergence and provide a suitable divergent cone of light. The lenses 1012a, 1012b, 1012c may be disposed between the corresponding light emitters 1002a, 1002b, 1002c, respectively, and one or more of the color mixing elements (e.g., color mixing elements 1004a, 1004b). In some designs, the 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 that 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 example embodiment of the illumination module 102 including a redirecting mirror 1004c in addition to the color mixing elements 1004a, 1004b. In the example shown, the redirecting mirror 1004c includes a prism or a portion thereof. The color mixing elements 1004a, 1004b may include a prism, such as a dichroic beam combiner prism as described above. The redirecting mirror 1004c has an angled reflective surface for redirecting the light beam. The angled reflective surface may be, for example, angled at about 30°-60° to one of the other sides of the prism, and in some embodiments, may be angled at about 45°. Thus, the redirecting mirror 1004c may include, for example, a 45° prism. The redirecting mirror 1004c may include a prism that redirects light by total internal reflection. The redirecting mirror 1004c may include an optically transparent 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. Each of the light emitters 1002a, 1002b, 1002c may be disposed adjacent to a corresponding color mixing element. Thus, light from the light emitters 1002a, 1002b, 1002c may be coupled into the respective 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, 1002c may be spaced apart from the corresponding color mixing elements 1004a, 1004b. Lenses 1012a, 1012b, 1012c may be included as shown in Figure 18G. The lighting module 102 may also include a diffuser 1008 as shown in Figures 18F and 18G. 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 may be applied to these structures.

[0171] 18H-18M respectively illustrate an example embodiment of an illumination module 102 similar to that described in FIG. 18B-18G, however, the illumination module 102 is tapered. FIG. 18H-18J shows an illumination module 102 including color mixing elements 1004a, 1004b, such as dichroic prisms, where one prism is larger than another. Similarly, one end of each color mixing element 1004a, 1004b is larger than another 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 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 or more tilted input surfaces as a result of having one end that is larger than the other end. 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. The input surface 1018c may correspond to the input surface of the color mixing element 1004b. The light emitters 1002a, 1002b may be positioned relative to these tilted input surfaces 1018a, 1018b, and the light emitter 1002c may be positioned relative to the input surface 1018c and may inject light into the 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 surface 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 the one in Figures 18H-18J. Thus, the discussion above with respect to 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 another. 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 or closest to the large end of the other color mixing element 1004b. The redirecting mirror 1004c may also include a prism with an angled reflective surface for redirecting the light beam, which is positioned adjacent or closer to the smaller end of the other color mixing element 1004b.

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

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

[0177] As illustrated in Figures 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, follow the divergence of the 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, 1002c, the color mixing elements 1004a, 1004b, and their arrangement may be similar to those described above with respect to Figures 18B-18M. For example, the color mixing elements 1004a, 1004b may include a prism, such as a dichroic prism, having a dichroic beam combiner that reflects light of certain wavelengths and transmits light of other wavelengths. 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, 1002c may be separated from the color mixing elements 1004a, 1004b by a gap. In some embodiments, one or more lenses may be disposed between the light emitters 1002a, 1002b, 1002c, which may be spaced apart from the color mixing elements 1004a, 1004b. Additionally, in some embodiments, the lighting module 102 includes a diffuser 1008. The characteristics and properties of the lighting module 102, the color mixing elements 1004a, 1004b, the lenses 1012a, 1012b, 1012c, and the diffuser 1008 are discussed above. Thus, any such characteristics or properties discussed herein may be applied to these structures. Advantageously, the light from the different color light emitters 1002a, 1002b, 1002c is combined and mixed together in the color mixing elements 1004a, 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 illumination 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 elements include a color combining or color mixing element 1666 (e.g., an x-cube).

[0181] FIG. 18N shows three light emitters 1002a, 1002b, 1002c. Each light emitter 1002a, 1002b, 1002c may correspond to a different color (e.g., red, blue, green). The light emitter 1002a may combine the different colors of light from the light emitters 1002a, 1002b, and 1002c and launch light into a color mixing element 1004, including wavelength-dependent combining elements 1006a, 1664b, 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, 1664b, may 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. The 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. The light emitters 1002b, 1002c may inject light into a surface of the color mixing element 1004 parallel and / or adjacent to the surface of the waveguide 112 closest to the SLM (bottom surface) (not shown). As shown, the 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. The light from the first emitter 1002a is transmitted through the dichroic combining element 1006a while the light from the second emitter 1002b is reflected from the first dichroic combining element 1006a such that the light from the first and second emitters 1002a, 1002b is combined and propagates along the same path to the second combining element 1006b, where the 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 a 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 a 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] FIG. 18O shows three light emitters 1002a, 1002b, 1002c in a different configuration than FIG. 18N. Each light emitter 1002a, 1002b, 1002c may correspond to a different color (e.g., red, blue, green). The first light emitter 1002a may launch light into a color mixing element 1004 including wavelength-dependent combining elements 1006a, 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, 1006b may be separate from and disposed relative to the waveguide 112. The combining elements 1006a, 1006b may include a dichroic coating. Light from the first emitter 1002a may be injected 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 on the side of the color mixing element 1004 opposite the SLM (e.g., furthest from).

[0184] Light from the first emitter 1002a may be incident on the first combining element 1006a, transmitted through it, 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 an obtuse angle in the implementation shown in FIG. 18O.

[0186] FIG. 18P shows three light emitters 1002a, 1002b, 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, 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, 1006b. Thus, the light from the first, second, and third emitters 1002a, 1002b, 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, 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 various different configurations are disclosed above. These configurations may include multiple dichroic beam combiner elements. In various configurations, these dichroic beam combiner elements were included 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., 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 an illumination module utilizing a beam combiner plate similar to the illumination module depicted in FIG. 18B-18M utilizing a dichroic (e.g., cube or right angle prism) prism. 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 be included. Thus, the properties, structures, and / or characteristics discussed above and elsewhere herein with respect to the illumination module 102 comprising a dichroic (cube or right angle prism) prism can be applied to an illumination module comprising a beam combiner plate. Still other variations, such as those described elsewhere herein, are also possible.

[0187] As illustrated in FIG. 19, the illumination system 1800 may include a delivery system 1802 between the illumination module 102 and the PBS 104 according to some embodiments. The delivery system 1802 may be, for example, a fiber optic delivery system. The illumination module 102 may include a coherent light emitter, such as a laser module. The laser module may include one or more lasers, and may include lasers of different colors. The different lasers may include lasers of one or more colors, such as, for example, red, green, and blue. The laser module may further include one or more combiners to combine beams from more than one laser. Such combiners may include one or more beam splitters or combiners, dichroic beam splitters or combiners, and / or fiber optic couplers to combine light from different sources, such as different color sources (e.g., lasers of different colors). The fiber optic delivery system 1802 may 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 may also include a 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 color light sources, are combined into a single fiber. The lighting module 102 may include multiple lasers, such as different color lasers. The output of the lighting module 102 (e.g., different color lasers) can be optically coupled to a multimode optical fiber. The different colored light from the lighting module 102 may be mixed within the fiber. The color mixing may occur inside the lighting 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 such that the illumination module 102 may efficiently deliver a 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 of the delivery system 1802 including optical fibers and the coupling capability over a distance may facilitate the use of an illumination module 102 including one or more laser modules at a remote distance from the polarizing beam splitter 104. For example, the illumination module 102 (e.g., a laser module) may be disposed on a unit that is 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 is wearable 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 from the head-mounted device may reduce heat emissions near the user's head, reduce the weight of an associated head-mounted system that is 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 power compared to other light emitters. Coherent light emitters also have narrow spectral bands. Narrow band coherent light emitters may output over a narrow range of wavelengths, for example, about 2 nm to 45 nm. In some embodiments, the range of wavelengths of narrow band coherent light emitters is about 10 nm to 40 nm. In some embodiments, the range of wavelengths of narrow band coherent light emitters is about 20 nm to 30 nm. Coherent light emitters 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 can be useful for color displays. The increased saturation of the coherent light emitter 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 optics. An optical fiber, having a small output area compared to a large LED, can enable coupling into a smaller input face of the waveguide 112 with reduced coupling losses. The waveguide 112 can therefore potentially be made smaller. In addition, 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 incoupling light into a smaller waveguide 112. A fiber laser can provide a narrower cone angle over the LED. In addition, the 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 prior to 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 necessary 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 transmissive mode using coherent light. In the transmissive 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 is reflected 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 disposed 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 illumination 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 reflection mode using incoherent light. In the reflection mode, the illumination module 102 launches light into a surface of the waveguide 112 opposite the end reflector 114. In some embodiments, the illumination module 102 launches light into a 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 disposed on a side of the illumination system 1800 proximate to 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 lasers 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 one or more different colored light emitters. 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 for a color emitter with a 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 a 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 light sources of different sizes and / or numbers of different colors.

[0200] 20A illustrates an exemplary light pipe integrator 1030 having three such areas, 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 emission regions or active areas of emitters for three different colors. In this embodiment, 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 a first, second, and third color of light, respectively. The difference in areas may be used to counteract reduced efficiency of emitters for certain 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 than the first or second color may be used. Alternatively or additionally, 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 than the first color may be used. Alternatively or additionally, 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 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 color. 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 color. 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 for different embodiments. In some embodiments, the color source emission areas 1032, 1034, 1036 may be spaced apart 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 color 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 are used, such as red, green, and blue. The colors may be different. Additionally, which source emission areas 1032, 1034, 1036 correspond to which colors may also vary. Still other variations are possible.

[0202] In some implementations, each of the three color source emission areas 1032, 1034, 1036 may 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 includes 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 may be, for example, 0.50 mm to 7.0 mm. In some embodiments, the width may be, for example, 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 may be, for example, 2.0 mm to 1.5 cm. In some embodiments, the length may be, for example, 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 source 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 source emitting area 1032 and the second color source emitting area 1034 may be separated by a first non-color section 1042, and the second color source emitting area 1034 and the third color source emitting area 1036 may be separated by a second non-color section 1044. The distance between the first color source emitting area 1032 and the second color source 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 source emitting area 1034 and the third color source 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 emission area 1032 may be disposed at the edge of the first surface of the light pipe integrator 1030. In some embodiments, the first color source emission 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 emission 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 emission 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 emission area 1034 may be disposed between the first color source emission area 1032 and the third color source emission area 1036. The second color source emission 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 emission 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 emission 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 emission area 1036 may be disposed at the edge of the first surface of the light pipe integrator 1030. In some embodiments, the third color source emission 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 emission 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 emission 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 sources (e.g., LEDs) 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 inner walls of the light pipe 1040 may be reflective (e.g., include a mirror coating). In some embodiments, such a reflective coating may facilitate improved mixing of light as the light 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 side walls by total internal reflection (TIR). In some embodiments, the optically transmissive material in the light pipe integrator 1030 through which the light propagates is diffusive. The diffusive material may be configured to scatter the light propagating within the light pipe integrator 1030 (e.g., scatter the light forward along the length of the light pipe integrator 1030), thereby mixing the different colors of light. In some embodiments, the light pipe 1040 may include scattering features, such as small particles, to aid in diffusing the light. For example, the light pipe 1040 may be a volume light integrator doped with diffusing particles.

[0210] FIG. 20B illustrates an exemplary light pipe integrator 1030 using an alternative arrangement of color source emission areas 1032, 1034, according to some embodiments. As illustrated in FIG. 20B, more than one color source emission area 1032, 1034, 1036 may be disposed along an edge of a 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 a third color source area 1036 by an 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 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 use one or more color emitters (e.g., laser diodes or light emitting diodes) to produce colored light, 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 may 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 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 state of the pixel 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 both sides of the SLM 1122. The polarizers 1116, 1118 may be crossed. Thus, the first polarizer 1116 may polarize the light, for example, into 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 different colors of light output by the lighting module 102 may 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 not activate 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 the 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 that can 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 a first time period, a pixel corresponding to a second color may be addressed 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, which may be coordinated with another SLM 106 that is illuminated with light from the illumination module 102 and produces 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 address different efficiencies associated with different colors, as described above with respect to FIGS. 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 FIGS. 20A and 20B also applies to the various configurations of lighting module 102 discussed with respect to FIGS. 21A-21C. For example, a lighting module 102 including a white light source 1110 and a color modulator as shown with respect to FIGS. 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 a lighting 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 disposed 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. The integrated structure of this extension may have a planar outer surface and, in some implementations, may have the shape of a right-angled prism. The light emitters 1002a, 1002b, 1002c may be butt-coupled to one or more of these outer surfaces to 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 include a hollow portion defined by an inner reflective sidewall through which light may propagate. As explained above, the inner reflective sidewall may be coated with a reflective coating. In some embodiments, one or both of the first and second regions include 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 manufactured as an integral (e.g., monolithic) element. In some embodiments, the first region and / or the second region are fabricated by combining or attaching different parts.

[0216] FIG. 21B shows an example of the embodiment of FIG. 21A with the light emitters 1002a, 1002b, 1002c and the dichroic combining elements 1022, 1024 of the 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 such that they are configured 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 tilted surfaces that direct light from the emitters 1002a, 1002b, 1002c along a common optical path. The color mixing elements, including the dichroic combining elements 1022, 1024, are arranged along this optical path. In some embodiments, the tilted input surface is tilted 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 illustrates an exemplary embodiment of the integrated structure of FIG. 21A with the dichroic combining element 1022 and the light integrator 1054 of the dichroic combiner 1052. The dichroic combining element 1022 is disposed 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 the 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, as compared to a design in which the dichroic combining element 1022 reflects light from a single color emitter, and such a configuration may be simpler to fabricate since the dichroic combining element 1022 involved, and potentially the number of components to be assembled, is reduced.

[0218] By using this technique to reduce the number of dichroic combining elements 1022 employed, one 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 consolidation 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 manufacturing simplification. Likewise, any property or feature discussed herein may be applied to structures and concepts discussed anywhere in this specification. Similarly, any property, feature, or concept discussed anywhere in this specification may be applied to other structures, features, or concepts described herein.

[0219] The light integrator 1054 may include a solid optically transparent material (e.g., plastic or glass) that includes diffusing features, such as particles or other scattering features, as shown in FIG. 21C, to allow the colors of light to mix more effectively. 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 semi-transparent material and / or a material that includes 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 where the light pipe integrator 1030 is hollow, the inner sidewalls from which the light reflects may be textured or coated to increase diffuse reflection. The inner sidewalls may be colored, for example, white. The mixing (e.g., color mixing) of light 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, which may potentially increase mixing, for example, may be utilized for the different design approaches described herein. Similarly, any property or feature discussed herein may be applied to the structures and concepts discussed anywhere herein. Similarly, any property, feature, or concept discussed anywhere herein may also be applied to other structures, features, or concepts described herein.

[0221] It may be advantageous to include a reflective lighting module configured for ingress on a first side and egress from a second (e.g., opposite) side at a location where light is displaced to reflect from the first and second opposite sides between ingress and egress. 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, an elongated lighting module body 1062 having one or more openings for receiving light from the one or more light sources 1064, 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 sidewall of the lighting module body 1062. The locations on the sidewall where the light source 1064 and the exit opening 1066 are located may be on opposite sides of the lighting module body 1062 as illustrated in FIGS. 22A and 22B. However, the locations on the sidewall where the light source 1064 and the exit opening 1066 are located may be on the same side of the lighting module body 1062 or other locations on the sidewall in some implementations. In some embodiments 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 being greater than 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 opposing walls) is at least greater than 2, or 3, or 4, or 5, or any value within 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 off an interior portion of the sidewall one or more times or two or more times. The interior portion of the sidewall may be coated to increase reflectivity. The interior portion of the sidewall 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 portion of the sidewall 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 include a substantially transparent material (e.g., glass or plastic). For example, the lighting module body 1062 may include 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 may propagate within the interior region from the one or more light sources 1064 to the output aperture 1066 and reflect off an interior portion of a sidewall one or more times or more than one time. 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 facilitate reflection. As discussed above, increasing the 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 a distinct color (e.g., red, green, blue) of light. 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 a polarizer, such as, for example, 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 a 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 illumination module body 1062, retained therein, and will 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 disposed 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, the 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 example reflective lighting module 1060 that additionally includes an extension 1072. The extension 1072 may be advantageous in directing the light output and / or increasing mixing (e.g., color mixing). The extension 1072 may be disposed between the reflective lighting module 1060 (e.g., along the aperture 1066) and the PBS 104 (not shown). The extension 1072 may be disposed adjacent to the reflective lighting module 1060 (e.g., along the output aperture 1066). The extension 1072 may have properties, characteristics, and / or properties similar to the light integrators described anywhere 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 may, in some implementations, be an extension 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., polarizing beam splitter 104 described above).

[0228] The various implementations described above are included within one or more separate color light emitters 1002a, 1002b, 1002c. Although 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, for example, a color light source. Such a light source may include a variable color light source whose color output may be varied and / or selected. In particular, the switchable color filter has an electrical input that may 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 cholesteric liquid crystals (CLC) as switchable color filters, 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 may span well across the spectrum, for example to include blue and red, and in various designs may have a broader spectral output. In some embodiments, a white light source may be used that emits visible white light. The broadband light source 1082 may output wavelengths that extend persistently over a range, or may include multiple peaks in wavelengths 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, such 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 separate 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 separate color CLC cells can be activated separately. When activated, the color CLC cells may block the transmission of a particular spectral region.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, 1088c are in the on state, respectively, the first, second, and third CLC cells 1088a, 1088b, 1088c can no longer block the previously blocked wavelengths (blue, green, and red, respectively). Thus, the 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 to produce (e.g., transmit) the first color (e.g., blue) from the broadband light source. Thus, the second CLC cell 1088b may be turned on, and the first CLC cell 1088a and the third CLC cell 1088c may be turned off to produce (e.g., transmit) a second color (e.g., green) from the broadband light source. Thus, the third CLC cell 1088c may be turned on, and the first CLC cell 1088a and the second CLC cell 1088b may be turned off to produce (e.g., transmit) a third color (e.g., red) 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 colors, fewer colors, 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 possible. As described above, for example, three different color light emitters 1002a, 1002b, 1002c may be used. FIG. 24 illustrates another perspective view of an illumination system, for example, according to some embodiments. As shown, the illumination system 1000 may include three illumination modules 102. As shown, the illumination modules 102 may each be configured to abut the waveguide 112. The illumination modules 102 may each be disposed along a common surface of the waveguide 112. In some embodiments, the illumination modules 102 may each be configured to emit light of a different color. In some embodiments, the illumination modules 102 are each configured to emit a different color (e.g., red, blue, green, respectively). The illumination modules 102 can be oriented to emit light parallel to each other and / or parallel to the surface of the waveguide 112. The illumination modules 102 may be configured to be time multiplexed. For example, the illumination 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 additional alternative structural and functional designs for systems and processes for motion-based content navigation through the principles disclosed herein. Thus, although specific embodiments and applications have been illustrated and described, it should be understood that the disclosed embodiments are not limited to the precise structures 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, the 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 an embodiment, the spatial light modulator 530 may be illuminated by an illumination system, where light from the optical module 540 is directed towards the optical 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 incoupling into a polarizing beam splitter (PBS) 1306 via incoupling optics 1304. The PBS 1306 is configured to direct light having a first polarization state (e.g., 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., p-polarization state), toward a viewer. In various embodiments, the modulated light can be conditioned by a projection optics 1302 disposed 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 depicted in FIG. 26, in which light from the light source 102 is generally emitted along a horizontal axis parallel to the x-axis. In such implementations that direct light 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 illuminate the spatial light modulator uniformly along the length of the spatial light modulator 106, 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 about 10 mm, the PBS 1306 is a cube with a length and height at least equal to 10 mm. In other embodiments of the illumination system, the PBS 1306 can have a dimension (e.g., length, width, height, or radius) greater than or equal to about 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 a 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 the 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.

[0234] 27 diagrammatically illustrates an embodiment of an illumination system 1000 configured to illuminate a spatial light modulator 106, which modulates the polarization of the incident light. The illumination system 1000 includes a polarizing beam splitter (PBS) 1306 configured to direct light having a first polarization state (e.g., 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., 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 the light from the source 102 can be emitted into a cone having a half angle of less than about 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 as 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 any of 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 where 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 may be reflected from the first surface 113A by a process of total internal reflection (TIR) ​​prior to being reflected by the end reflector 114.

[0236] In various designs, one or more redirecting features 1314 are disposed across the second surface 113B. The redirecting features 1314 may be configured to redirect light reflected from the end reflector 114 toward the spatial light modulator 106. The redirecting 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 that is 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 along 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 embodiments. 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 a value 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 any value within these ranges / subranges or 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 a plurality of turning features 1314.Without being bound to any particular theory, the pitch of the multiple 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 inclined 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 inclined or inclined towards the light input surface 113C. The inclination 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 any sub-range within these ranges / any range formed by any of these 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 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 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 may 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 about 41 degrees relative to the optical axis of the LED (which may be aligned parallel to the x-axis). In such an embodiment, the tilt angle 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 the spatial light modulator 106 or a front surface thereof such that substantially all light output from the light source 102, including the LED, is coupled into the waveguide 112. The tilt angle of the second surface 113B and / or the height of the light input surface 113C can be reduced if the light source 102 is low divergence. For example, if the light source 102 is coupled to the input surface 113C via an optical fiber, the tilt angle of the 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 redirecting 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 the redirecting 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 include one or more dielectric layers, such as a multi-layer 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] In the embodiment depicted in FIG. 27, the end reflector 114 can be a curved mirror (e.g., a spherical or parabolic mirror). Thus, the end reflector 114 can have optical power and can 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 light reflected from the redirecting 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-polarized state) is transmitted. The modulated light from the spatial light modulator 106 includes light having the second polarization state (e.g., a p-polarized 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 redirecting features that include a polarization-selective element. As discussed above, the polarization-selective element can include a coating or a wire grid. In the embodiment illustrated in FIG. 28A, a pair of facets of each redirecting feature is at least partially coated with a polarization-selective coating configured to, for example, reflect a first polarization state (e.g., an s-polarized state) and transmit a second polarization state (e.g., a p-polarized 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-polarized 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 the polarization and produce an image. In addition, 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 the thin film coatings that can selectively reflect a first polarization state and transmit a second polarization state can have a small incidence angle range. For example, some embodiments of the thin film coatings that can selectively reflect a first polarization state and transmit a second polarization state may not function efficiently when the acceptance angle of the light varies from the design incidence angle by more than about ±10 degrees. For example, if a facet with 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 with 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 in which 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 in which 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 incidence angle, a wire grid can be disposed at least partially across one of the facets of the turning feature pair.

[0247] As shown in FIG. 28B, the polarization selective element can be disposed over a portion of the facet that receives light from the end reflector 114. The other facet need not include a polarization selective element or coating. In the embodiment depicted in FIG. 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 be devoid of 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 it strikes 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 surface of the microstructure or redirecting feature 1314 can reflect light reflected from the end reflector 114 such 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. Having the second surface 113B angled 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. In addition, the contrast ratio of the spatial light modulator 106 can be increased because the end reflector 114 and redirecting features 1314 are configured to direct light toward the spatial light modulator 106 along a normal or near-normal direction 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. In addition, the illumination system 1000 can be capable of color sequential and color filter-based operation.

[0251] As discussed above, the redirecting features 1314 need not be located in a region of the second surface 113B that extends beyond the spatial light modulator 106. For example, referring to FIG. 27, light ray 124A that, after total internal reflection 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 redirecting feature 1314, and therefore will not be directed towards the spatial light modulator 106. Furthermore, light that is emitted along the optical axis of the light source 102 and is incident on a portion of the end reflector 114 outside the box 1322 will be reflected back towards the light input surface 113C and will not be directed towards 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 an area 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 the light source 102. In such an embodiment, the turning feature (e.g., turning feature 1314) may be configured to provide a refractive power and redirect the 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 to 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., about ±41 degrees relative to the optical axis of the light source 102 along a horizontal axis parallel to the x-axis along a direction parallel to the x-axis). The reflecting holographic structure 1348 can be configured to collimate light from multiple light sources. In various embodiments, the reflecting 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 way, the reflecting 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 reflecting holographic structure 1348. The reflecting 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 a 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 an 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., including a plurality of thin films, one or more dielectric coatings, or a wire grid) at least partially on the turning feature, 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 that is not redirected by the turning feature 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 that is not redirected by the turning feature.

[0256] In embodiments of the illumination system that employ light recycling, as 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. In addition, 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 the illumination system that employ light recycling, as shown in Figure 34 discussed herein, a half-wave plate can be placed 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 placed 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 may 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 may advantageously increase the efficiency of light usage of the device. Although these illumination devices emit light of a particular polarization state (e.g., s-polarized state) onto the spatial light modulator, the light may be modulated. To improve the efficiency of light usage, light that is not emitted to and / or received by the spatial light modulator may be recycled. For example, a light recycling system may be configured to convert light having a polarization state (e.g., p-polarized state) that is not useful for the spatial light modulator into light of another polarization state (e.g., s-polarized state) that may 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 disposed relative to the light emitter 5010, such as a waveguide 5015, that receives the light 5012 and redirects 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 and receives 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 launched 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., in this embodiment, p-polarized light) that is not used by the spatial light modulator 5025 into light having a first polarization state (e.g., s-polarized light) 5035 that is usable by the spatial light modulator 5025. Thus, instead of some light being unused, by converting the light having the second polarization state into light having the first polarization state, additional light can be launched 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 (hereafter 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-polarized state) and a second polarization state (e.g., a p-polarized state). The light emitter 5010 can also include any of the light emitters or other types of emitters disclosed herein. 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 may also include at least one light redirecting optical element, which may include a waveguide 5015 disposed 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 may be guided within the waveguide 5015 by total internal reflection (TIR). The waveguide 5015 may include any of the light redirecting optical elements described herein. For example, the waveguide 5015 may include plastic, glass (e.g., in some embodiments, high index glass), or a combination thereof. As described herein, the waveguide 5015 may act as a polarizing beam splitter and reflect light 5020 having a certain polarization state (e.g., in this embodiment, an s-polarization state) to the spatial light modulator 5025. In some examples, 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 having a second polarization state (e.g., a p-polarization state) (not shown). The waveguide 5015 can include one or more redirecting elements (e.g., on the angled surface 5015a) configured to redirect light (e.g., light having a certain polarization state) guided within the waveguide 5015 out of the waveguide 5015 to the spatial light modulator 5025. The angled surface may include polarization selective elements or structures that may operate differently with respect to different polarization states. For example, the redirecting elements can include redirecting features (e.g., microstructures 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 may 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 include the same or similar material as the waveguide 5015 (e.g., plastic, glass, or a combination thereof). The compensation layer 5016 can reduce the effect of refraction 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 that 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 5015a 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 a 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 a second polarization state (e.g., a p-polarization state) depending on the state of the pixel.

[0264] Light that is not directed out of the waveguide 5015 to the spatial light modulator 5025, e.g., not in the desired first polarization state (e.g., s-polarization state), may continue to propagate through the waveguide 5015. This light may not be reflected out of the waveguide 5015 by the 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) to 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 an 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 back into the waveguide 5015 that may otherwise escape out of the edge of the waveguide 5015. The reflective element 5030a may include various reflective elements, including various reflective elements described anywhere herein. The reflective element may include a 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 examples, 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 examples, 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 disposed 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-polarized state) to light having a first polarization state (e.g., s-polarized state). The polarization converter element 5030b may include a polarization rotator that rotates the orientation of the linear polarization. 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, for example, a quarter-wave retarder. Passing through the quarter-wave retarder may, in some cases, introduce a 180° retardation between the orthogonal polarizations, affecting the rotation of the linear polarization. Thus, 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 (hereafter 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-polarized state) and launch the light out of 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 to 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 be incident 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 reflect light from the quarter-wave retarder 5130b incident on the reflective element 5130c back through the quarter-wave retarder 5130b. The pair's passage through the quarter-wave retarder 5130b may, in some cases, introduce a 180° phase between the orthogonal polarization 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 the light reflected from the first reflective element 5130a ultimately reaches (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 a second polarization state (e.g., a p-polarization state) can be converted into recycled light 5135 having a first polarization state (e.g., an s-polarization state).

[0270] The quarter-wave retarder 5130b may be a birefringent material (e.g., quartz) 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 light's polarization while reflecting it back towards the quarter-wave retarder 5130b. In some embodiments, the reflective element 5130c can 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 may be changed from circularly polarized back to linearly polarized, where it has a rotated linear polarization state (e.g., an s-polarization state). The recycled light may propagate back through 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 redirecting feature) to the spatial light modulator 5125 to improve 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., can include redirecting features) that reflects light having a first polarization state (e.g., s-polarized state) and transmits light 5140 having a second polarization state (e.g., p-polarized 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 that is 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 materials as for the reflective element 5130c. For example, the reflective element 5130d can include a mirror coating. The reflective element 5130d can be configured to reflect 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 a 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. This light can continue through the quarter-wave retarder 5130b to the second reflective element 5130c associated therewith and can be reflected again through the quarter-wave retarder 5130b, thereby rotating the 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, the 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, for example, reflective element 5130a, reflective element 5130d, quarter-wave retarder 5130b, and reflective element 5130c. This light is again reflected from the first reflective element 5130a to the 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 launched out of the waveguide 5115 (e.g., via a redirecting element on the angled surface) to the spatial light modulator 5125 to improve the efficiency of the 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 can include one or more light emitters 5210 (hereafter 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 can include a reflective element 5230a disposed against an edge of the waveguide 5215 to reflect light received from the light emitters 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., s-polarization state) to the spatial light modulator 5225. In some embodiments, the waveguide 5215 can have an angled surface 5215a (e.g., can include a redirecting element) to reflect light 5220 having a first polarization state (e.g., s-polarization state) and transmit light 5240 having a second polarization state (e.g., p-polarization state). Thus, light from the light emitter 5210 having a first polarization state (e.g., s-polarization state) reflected by the first reflecting element 5230a to the angled surface 5215a is reflected toward the spatial light modulator 5225. The 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. A compensation layer 5216, as described above, may be disposed over angled surface 5215a to counter refraction otherwise caused by angled surface 5215a.

[0276] To improve the efficiency of light usage, the light recycling system can also include a polarization rotator, such as a half-wave retarder 5230b. The half-wave retarder 5230b can be disposed relative to an edge of the waveguide 5215, for example, on or proximate an 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 a 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-polarized state) can then be launched out of the second waveguide 5245 (e.g., via a redirecting element) to 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 (which can include, e.g., a redirecting element) to reflect the light 5255 having the first polarization state (e.g., s-polarized state) to the second spatial light modulator 5260. Similarly, the second waveguide 5245 can include a second optical compensation layer 5246 to counter 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 disposed 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 launch 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 a 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 nano- or microstructures configured to eject 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 a grating, a holographic optical element, or other structure.

[0280] In some embodiments, the redirecting element may 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] The wire grid 5427b may be tuned to the wavelength of the light produced by the light emitter 5410 to reflect light of a particular polarization state and transmit light of another polarization state. For example, as illustrated in FIG. 36, the 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 the light 5420 having the first polarization state (e.g., s-polarization state) to the spatial light modulator 5425, while the light 5422 having the second polarization state (e.g., p-polarization state) can continue to propagate through the 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 the waveguide 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 to allow light that reaches the edge waveguides 5315, 5415 and is not launched into 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 may be configured to reflect 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 to 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 having the second polarization state (e.g., p-polarization state) being not used, the light having the second polarization state (e.g., p-polarization state) can be directed to and used by the spatial light modulator 5325, 5425 and converted to light having the first polarization state (e.g., s-polarization state), which can contribute to producing an image, thereby improving the efficiency of the device.

[0285] As shown in Figures 35 and 36, some embodiments may also include a polarizer 5350, 5450 between the waveguide 5315, 5415 and the spatial light modulator 5325, 5425. Such a polarizer 5350, 5450 may be used to produce an intensity image from the spatial light modulator 5325, 5425, which operates on the polarized light and selectively modulates the polarization state. The polarizer 5350, 5450 may transmit one linear polarization state and attenuate another, such that the spatial light modulator 5325, 5425 exerts 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 a light recycling system to improve the efficiency of light usage of 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 that includes a light recycling system. In addition, the exemplary light recycling systems described herein or any feature or combination thereof can be incorporated within any of the other designs described herein or combined with any feature or combination of features of any other designs described herein.

[0287] FIG. 37 illustrates an illumination device 1400 with an internal coupling element 1654 that deflects light to couple into the 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 illustrated 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. This 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 the 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 in an augmented reality display device. The illumination system may be configured in optical communication with an eyepiece. In some implementations, the eyepiece may comprise one or more waveguides disposed within the user's field of view. As described herein, an image may be presented to the user's eye when the eye is looking through the eyepiece. In certain implementations, the eyepiece comprises a waveguide stack, although the use of the polarizing beam splitter and illumination system as described herein should not be so limited. FIG. 38 illustrates an example illumination system 1000 coupled to an eyepiece, and in particular 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 incoupling optical elements 144, 146, 148. The illumination system 1000 may be in optical communication with (e.g., disposed along its optical axis) the waveguide stack 166. In some implementations, the illumination system 1000 may be configured to abut one or more elements of the waveguide stack 166 or may be separated therefrom. For example, the refractive optical element 118 may abut a surface of the waveguide 158 and / or the incoupling optical element 148. However, abutment is not required. The illumination system 1000 may 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 of the 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 of the 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 some implementations, one or more of the 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 the optical module 540 (FIG. 6). The polarizing beam splitter 104 may correspond to other elements described herein, such as the 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 a viewer. A wide variety of variations of such systems (and subsystems and components) are also contemplated.

[0291] Similarly, any property or feature 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 herein. Similarly, any property, feature, 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 feature discussed herein can be applied to other structures and concepts discussed anywhere herein. EXEMPLARY ASPECTS (Example) (Examples 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 disposed at a location 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 disposed 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 to the axis by a wedge angle α; a light input surface between the first surface and the second surface and configured to receive light emitted from the light source; an end reflector disposed on a side opposite the light input surface; and 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 disposed relative to the wedge-shaped light redirecting element to receive the light emitted from the wedge-shaped light redirecting element and modulate the light; 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 being configured to redirect light reflected by the end reflector towards the first surface. 3. The system of any one of claims 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. A 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 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. The system of any of Examples 10-14, wherein the turning feature comprises a first and a second portion, 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 multiple 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 example 1-22, wherein the end reflector comprises a reflective holographic structure comprising one or more holograms. 26. A system described in any of Examples 1-22, wherein an end reflector is configured to collimate light from the light source and direct the collimated light to 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, the surface opposite the end reflector having 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 through the input surface into a wedge-shaped light redirecting element, 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 described in 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. (Examples 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 and configured to receive light emitted from the light source; an end reflector disposed on a side opposite the light input surface; and a plurality of light redirecting features disposed on the second surface; Equipped with the second surface is angled 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 towards 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 as 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 a 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 the 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 across the refractive optical element. 11. The optical device according to any one of Examples 1-10, 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. (Examples 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 disposed 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 that is not emitted to the spatial light modulator to pass through the reflective element, the reflective element being 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 to receive light reflected by the reflective element and convert 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 to reflect 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, the light recycling system further comprising 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, the second waveguide configured to emit light having a first polarization state to the second spatial light modulator. 18. The display device of example 17, wherein the second waveguide has a second angled surface and 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. The display device of 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. 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 one of Examples 1-29, comprising a transmissive spatial light modulator. (Examples 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 disposed between the first surface and the second surface and relative to the light delivery system for receiving light emitted from the light module via an optical fiber; an end reflector disposed on a side opposite the light input surface; and Equipped with the second surface is angled 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 a polarization-maintaining fiber. 4. A device described in any of Examples 1-3, wherein the optical module comprises multiple optical emitters. 5. The device of example 4, wherein the plurality of light emitters comprises light emitters of different colors. 6. The device of 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 end reflector disposed on a side opposite the light input surface; and Equipped with the second surface is angled 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 an 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 color 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 optical emitters, the optical module combining light for the plurality of emitters; a light input surface disposed 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 end reflector disposed on a side opposite the light input surface; and Equipped with the second surface is angled 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 optical 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. A device described in 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 disposed relative to the optical module between the first surface and the second surface for receiving light therefrom, the optical input surface comprising microstructures or nanostructures; an end reflector disposed on a side opposite the light input surface; and the second surface is angled 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 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 grating. 4. A device according to any of the above 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 above 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 disposed at a location 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 disposed 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; and a light input surface between the first surface and the second surface and configured to receive light emitted from the light source; an end reflector disposed on a side opposite the light input surface; and 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 disposed relative to the polarization sensitive light redirecting element to receive the light emitted from the polarization sensitive light redirecting element and modulate the light; 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 towards the first surface. 3. The system of any one of claims 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. A 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 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. The system of any of Examples 10-14, wherein the turning feature comprises a first and a second portion, 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 multiple 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 example 1-22, wherein the end reflector comprises a reflective holographic structure comprising one or more holograms. 26. A system described in any of Examples 1-22, wherein an end reflector is configured to collimate light from the light source and direct the collimated light to 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 embodiments 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, the surface opposite the end reflector having 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 through the input surface into a polarization-sensitive light redirecting element, 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. 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 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 according to 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. A system described in 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 in 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 to the axis by a wedge angle α; a light input surface between the first surface and the second surface and configured to receive light emitted from the light source; an end reflector disposed on a side opposite the light input surface; and 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 disposed relative to the wedge-shaped light redirecting element to receive the light emitted from the wedge-shaped light redirecting element and modulate the light; A lighting system comprising: 2. The lighting system of Example 1, wherein the wedge-shaped light redirecting element comprises a polarization selective element on a second surface, the polarization selective element being 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 as 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 being configured to redirect light reflected by the end reflector towards the first surface. 10. The illumination system of example embodiment 9, wherein the plurality of redirecting features comprises a polarization selective element. 11. The illumination system of example embodiment 10, wherein the polarization selective element comprises a thin film, a dielectric coating, or a wire grid. 12. The illumination system of any of Examples 9 or 10, wherein the plurality of redirecting features are configured to redirect a portion of light receive...

Claims

[Claim 1] The invention described in this specification.

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