Folding light guide of plane endoscope

Abstract

According to an example, an optical device may include: a light guide optical element having a front surface and a rear surface parallel to each other; a reflector configured to receive the plurality of guided image light beams and to reflect a plurality of reflected guided image light beams, the plurality of guided image light beams and the plurality of reflected guided image light beams propagating within the light guide optical element between the front surface and the rear surface; a first aperture expander having a first plurality of partially reflective parallel facets configured to expand the plurality of reflected guided image beams and provide a first plurality of expanded image beams; and a second aperture expander having a second plurality of partially reflective parallel facets configured to expand the first plurality of expanded image beams and to provide a second plurality of expanded image beams configured to exit from the back surface.

Description

Technical Field

[0001] This application is based on and claims the benefit of priority under 35 USC 119(e) to U.S. Patent Application No. 63 / 393,928, filed on July 31, 2022, entitled In-plane Mirror Folded Lightguide, the entire disclosure of which is incorporated herein by reference in its entirety. This application is also based on and claims the benefit of priority under 35 USC 119(e) to U.S. Patent Application No. 63 / 453,327, filed on March 20, 2023, also entitled In-plane Mirror Folded Lightguide, the entire disclosure of which is incorporated herein by reference in its entirety. Background Art

[0002] Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section. The present disclosure generally relates to systems and methods for presenting information to a user, and more particularly to optical systems and near-eye displays for presenting information to a user.

[0003] Wearable optical devices (e.g., near-eye displays or smart glasses) are often bulky to wear, thus limiting their comfort and usefulness. Additionally, some wearable optical devices have limited ability to view surrounding scenes, or do not have wide viewing angles due to obstructions in the field of view caused by the presence of various optical components. Finally, awkward placement of the image projector may require the location of the image injection point to be placed relatively far from the image output coupling region, resulting in degradation of image quality due to the longer image path. What is needed is a solution to these and other problems. Summary of the invention

[0004] According to an example, an optical device is generally described. The optical device may include: a light guide optical element having a front surface and a rear surface parallel to each other; a reflector configured to receive a plurality of guided image beams and reflect a plurality of reflected guided image beams, the plurality of guided image beams and the plurality of reflected guided image beams propagating between the front surface and the rear surface within the light guide optical element; a first aperture expander having a first plurality of partially reflective parallel facets, configured to expand the plurality of reflected guided image beams and provide a first plurality of expanded image beams; and a second aperture expander having a second plurality of partially reflective parallel facets, configured to expand the first plurality of expanded image beams and provide a second plurality of expanded image beams.

[0005] According to this example, the optical device, wherein the plurality of guided image beams may have a guided image beam central axis, wherein the plurality of reflected guided image beams may have a reflected guided image beam central axis, and wherein the angle between the guided image beam central axis and the reflected guided image beam central axis may be greater than 90°. The optical device, wherein the reflector may be at least one of: disposed perpendicularly to the front surface; and disposed on the peripheral edge of the light-guiding optical element, the reflector may be configured to completely reflect the received plurality of guided image beams. The optical device may also include an input coupler configured to receive a collimated first image beam from an image projector and output a plurality of guided image beams, the plurality of guided image beams propagating between the front surface and the rear surface within the light-guiding optical element, wherein the input coupler may be disposed to be adjacent to one of the front surface and the rear surface and at least partially embedded within the light-guiding optical element, and wherein the input coupler is one of a prism, a diffraction element, a reflective element, or a holographic element.

[0006] According to the example, the optical device, wherein the reflector can be a mirror facing the inner portion of the light-guiding optical element and disposed adjacent to the peripheral edge of the light-guiding optical element in one of the following positions: vertically below the input coupler, and vertically above the input coupler. The optical device, wherein the first plurality of partially reflective parallel facets can be tilted at a first angle, the first angle being one of the angles tilted relative to at least one of the front surface and a transverse plane perpendicular to the front surface; and wherein the second plurality of partially reflective parallel facets are tilted at a second angle, the second angle being one of the angles tilted relative to at least one of the front surface and a transverse plane perpendicular to the front surface. The optical device, wherein at least one of the first plurality of partially reflective parallel facets and the second plurality of partially reflective parallel facets can include an angle-selective coating.

[0007] According to this example, the optical device, wherein the upper portion of the light-guiding optical element may include an optically clear line of sight region, and wherein the second aperture expander may be disposed vertically below the line of sight region. The optical device, wherein the first aperture expander may be configured to expand a plurality of reflected guided image beams in a first dimension, the second aperture expander may be configured to expand a first plurality of expanded image beams in a second dimension, and the first dimension and the second dimension may be substantially orthogonal to each other. The optical device may also include a shading member disposed on a portion of the front surface adjacent to the reflector, the shading member may be configured to perform at least one of the following: reduce scattering of the plurality of guided image beams, and reduce the effects of ambient light on the reflector. The optical device, wherein the second plurality of expanded image beams are configured to emerge from the rear surface.

[0008] According to an example, an optical system is generally described. The optical system may include: a light guide optical element having a front surface and a rear surface parallel to each other; an image projector, which may be configured to generate a collimated first image beam based on a digital image, wherein the collimated first image beam is collimated to infinity; an input coupler, which is configured to receive the collimated first image beam and output a plurality of guided image beams within the light guide optical element, the plurality of guided image beams propagating between the front surface and the rear surface; a reflector, which is configured to receive the plurality of guided image beams and reflect a plurality of reflected guided image beams, the plurality of guided image beams propagating between the front surface and the rear surface within the light guide optical element; a first aperture expander having a first plurality of partially reflective parallel facets, which is configured to expand the plurality of reflected image beams in a first dimension and provide a first plurality of expanded image beams; and a second aperture expander having a second plurality of partially reflective parallel facets, which is configured to expand the first plurality of expanded image beams in a second dimension and provide a second plurality of expanded image beams, the second plurality of expanded image beams being configured to exit from the rear surface.

[0009] According to the example, the optical system, wherein the input coupler can be disposed adjacent to one of the front surface and the rear surface and at least partially embedded within the light-guiding optical element, and wherein the input coupler can be one of a prism, a diffractive element, a reflective element, or a holographic element. The optical system may also include: a frame configured to support at least a portion of the image projector and the light-guiding optical element, the frame configured to be worn on a portion of the user's head adjacent to the user's eyes; an optical engine configured to receive a digital image and operate the image projector; and a controller configured to operate the optical engine and the projector. The optical system, wherein the plurality of guided image beams may have a guided image beam central axis, wherein the plurality of reflected guided image beams may have a reflected guided image beam central axis, and wherein the angle between the guided image beam central axis and the reflected guided image beam central axis may be greater than 90°.

[0010] According to the example, the optical system, wherein the reflector can be a mirror facing the inner portion of the light-guiding optical element and disposed adjacent to the peripheral edge of the light-guiding optical element, which can be one of the following: vertically below the input coupler, and vertically above the input coupler, the reflector can be configured to completely reflect the received multiple guided image beams. The optical system, wherein the first aperture expander can include a plurality of partially reflective parallel facets, which are inclined at one of the following angles: inclined relative to the front surface and at least one of the lateral planes perpendicular to the front surface and perpendicular to the front surface. The optical system, wherein at least one of the first plurality of partially reflective parallel facets and the second plurality of partially reflective parallel facets can include an angle-selective coating. The optical system, wherein the upper portion of the light-guiding optical element can include an optically clear line-of-sight region, and wherein the second aperture expander can be disposed vertically below the line-of-sight region. The optical system may also include a partially planar reflector arranged in the light-guiding optical element parallel to the front surface; and a shading member may be arranged on a portion of the front surface adjacent to the reflector, and the shading member may be configured to perform at least one of the following: reduce scattering of multiple guided image light beams, and reduce the impact of ambient light on the reflector.

[0011] The foregoing summary is illustrative only and is not intended to be limiting in any way. In addition to the above illustrative aspects, embodiments, and features, other aspects, embodiments, and features will become apparent by reference to the accompanying drawings and the following detailed description. In the accompanying drawings, the same reference numerals indicate the same elements or functionally similar elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A block diagram of an optical system according to various examples of the present disclosure is shown.

[0013] Figure 2A A front plan view of an optical device including a light-guide optical element (LOE) according to various examples of the present disclosure is shown.

[0014] Figure 2B Various examples according to the present disclosure are shown. Figure 2A Side plan view of the optical device.

[0015] Figure 3A A front plan view of an optical system including a light guide optical element according to various examples of the present disclosure is shown.

[0016] Figure 3B Various examples according to the present disclosure are shown. Figure 3A Side plan view of the optical system.

[0017] Figure 4 A schematic isometric view of a portion of an aperture expander having partially reflective parallel facets according to various examples of the present disclosure is shown.

[0018] Figure 5 A front plan view of an optical device including a light-guiding optical element according to various examples of the present disclosure is shown.

[0019] Figure 6 A front plan view of an optical device including a light-guiding optical element according to various examples of the present disclosure is shown. DETAILED DESCRIPTION

[0020] In the following description, in order to provide an understanding of the various embodiments of the present application, many specific details are set forth, such as specific structures, components, materials, dimensions, processing steps and techniques. However, it will be appreciated by those skilled in the art that the various embodiments of the present application may be practiced without these specific details. In other cases, in order to avoid making the present application unclear, well-known structures or processing steps are not described in detail.

[0021] As will be described in more detail below, wearable devices (e.g., near-eye displays and / or smart glasses) can be implemented using the systems and methods described in accordance with the present disclosure. The system can efficiently provide high-quality optical information to users in a variety of applications.

[0022] Figure 1 A block diagram of an optical system according to various examples of the present disclosure is shown. The optical system 100 may include two or more devices or components. The optical system 100 may generally be implemented as a hybrid system including various electronic, optical, and electro-optical elements. The optical device 102 may include one or more elements from the optical system 100. As will be described in more detail below, the optical system 100 may include a wearable device 110, such as one or more near-eye displays or smart glasses, which may be worn on or around the head of a user to transmit optical information to one or more eyes of the user.

[0023] The wearable device 110 may include a controller 114 having a memory 116, wherein the controller 114 may be configured to, for example, send or receive electrical signals to various other elements in the optical system 100, execute program instructions stored in the memory 116 to process information and provide information, operate the wearable device 110, and interact with other systems external to the wearable device 110. The controller 114 may include a microcontroller, a processor, various discrete components, a programmable logic device, and / or various interface circuits that can access the memory 116, which may be removable, replaceable, programmable, and reprogrammable to update the instructions of the controller 114.

[0024] The wearable device 110 may also include a power management module 120 having a battery 122, wherein the power management module 120 may be configured to charge, discharge, and monitor power usage of the battery 122. Various elements of the wearable device 110 may receive power from the battery 122, including, for example, a controller 114, one or more image projectors 126 (e.g., projection optics devices, or PODs), and an optical engine 134 having one or more digital image processors 136.

[0025] The wearable device 110 may also include one or more image projectors 126, each configured to generate a collimated image beam based on a digital image 136. The collimated image beam may be an illuminated representation of a digital image having an image field, which is a two-dimensional representation of a digital image based on a single graphic image (e.g., a static image) or a sequence of graphic images (e.g., a moving image). The collimated image beam may be collimated to infinity.

[0026] The wearable device 110 may also include one or more light-guiding optical elements 130 (e.g., LOEs, also denoted as waveguides WG), which include a transparent material configured to receive and propagate light, wherein the light may enter and exit from various outer and inner surfaces of the light-guiding optical elements 130. For example, the transparent material comprising the light-guiding optical elements 130 may include optical glass or other suitable materials, which are transformed into complex optical structures using processes that may include coating, laminating, slicing, polishing, and shaping transparent materials. For example, the process may include adding partially reflective materials or fully reflective materials, such as mirror coatings. Similarly, for example, the process may also include adding partially opaque or fully opaque materials such as visors to block light.

[0027] The wearable device 110 may also include one or more optical engines 134 coupled to the one or more image projectors 126 and the light guide optical element 130. The optical engine 134 may be configured to directly operate the image projector 126 under the direction of the controller 114. For example, the optical engine 134 may provide graphics processing of a digital image before the image projector 126 projects an illuminated representation of the digital image.

[0028] The wearable device 110 may also include a frame 138 (e.g., structure) for supporting and holding one or more elements in the wearable device 110. For example, the frame 138 may support and hold the first image projector 126 in a position adjacent to the first light-guiding optical element 130. Similarly, the frame 138 may support and hold the second image projector 126 in a position adjacent to the second light-guiding optical element 130. In this manner, the frame 138 may support and hold a pair of one or both image projectors 126 and light-guiding optical elements 130 on or around the user's head. References are made herein to the orientation of various elements relative to each other. Such references may also include references to various elements of the wearable device 110 when supported by the frame 138, or to three-dimensional (3D) references (e.g., X-axis, Y-axis, Z-axis), as described in the associated figures.

[0029] The optical system 100 may also include a host computer 170, which may include a processor 174 configured to read and execute operations based on instructions 178 stored in a computer-readable medium 180. The instructions 178 may include at least some instructions provided to the controller 114 and stored in the memory 116. The host computer 170 may communicate with one or more elements of the wearable device 110 via a signal and power bus 188. In this manner, the host computer 170 may provide power to charge the battery 122, provide instructions to and receive status from the controller 114 and various other elements of the wearable device 110, and provide digital image data to the optical engine 134.

[0030] Figure 2AA front plan view of an optical device including a light-guide optical element (LOE) according to various examples of the present disclosure is shown. The optical device 102 may include a light-guide optical element 130 having an aperture expander 16 disposed at least partially within the light-guide optical element 130. As will be described more fully below, the aperture expander 16 may include a plurality of partially reflective parallel facets 19 (e.g., internal planar surfaces) configured to receive a plurality of light beams from a first direction and expand the beam width of the received light beams or the aperture of the light in a second direction, which second direction may be different from the first direction and may also be substantially orthogonal to the first direction. In this way, the aperture expander 16 may be configured to expand the received light beams in two dimensions.

[0031] The term facet can generally refer to a reflective optical structure having a flat surface. Each facet can include an angle selective coating that can have an optical axis that deviates from the coating normal angle so as to selectively pass or attenuate illumination having the same or different orientations, respectively. As used herein, an aperture expander can include a plurality of planar, mutually parallel and partially reflective optical elements (e.g., facets) spaced apart from one another, and these optical elements can be included, for example, at angles that can be tilted relative to at least one major outer surface of the light-guiding optical element 130. Thus, each facet 19 in the aperture expander 16 can be parallel to one another and set at the same tilt angle. In addition, the facets described herein can include an angle selective coating and can be controlled to have multiple states (e.g., on / off) or to change the level of reflectivity and / or transmittance of each facet or set of cooperating facets in the structure. The last facet in the structure (e.g., the terminal facet) can be fully mirrored (e.g., not partially mirrored) to reflect any remaining illumination that may have passed through the previous facets in the structure. Alternatively, each facet may have the same partial reflectivity for consistency, reduced complexity, and simpler construction.

[0032] As used herein, the term generally refers to a tolerance less than one degree, wherein substantially orthogonal may refer to two lines or two planes intersecting at an angle that can be compared visually to about 90 ° but can be less than 89.5 ° and 90.5 °, for example. Similarly, substantially vertical may refer to an angle of about 90 ° with a vertical plane, and the angle with the vertical plane may, for example, be less than 89.5 ° and 90.5 °, and change. Finally, substantially horizontal (e.g., or substantially horizontal) may refer to an angle of 0 ° with a horizontal plane, but the angle with the horizontal plane may, for example, be less than +0.5 ° and -0.5 °, and change. In this way, verticality may be very precise, and in some examples may generally refer to a change that is much less than 1 ° (e.g., <<1 °) on a magnitude of less than 0.1 °, 0.05 °, or 0.01 °.

[0033] The light guide optical element 130 may also include an input coupler 14 located at a location 15, which may be on, near, or embedded within a peripheral edge of the light guide optical element 130. The input coupler 14 may be an optical element configured to conduct image illumination into the optical element 130. Alternatively, the input coupler 14 may be located at any suitable location capable of performing as described herein. Thus, as Figure 2B , the location of the input coupler 14 at position 15 is not considered to be limiting. As will be described more fully below, the input coupler 14 can be located on, near, or embedded within a portion of the light-guiding optical element 130, and can be configured to couple light from the image projector 126 into the light-guiding optical element 130. For optimal beam propagation, it may be preferred that the injection angle of the input image beam from the image projector 126 can be shallow to promote total internal reflection (TIR) ​​so that the beam can propagate with minimal escape while remaining within the light-guiding optical element 130 (e.g., to reduce scattering). The input coupler 14 can be a prism, a diffractive element, a reflective element, or a holographic element. When the input coupler 14 is a prism, the input coupler 14 can be rotated so that the image projector 126 can be mounted near the light-guiding optical element 130 in a manner that is less obtrusive to the user. As Figure 2A , Figure 2B As shown in the drawings, and similar to the other drawings, a three-dimensional (3D) framework with reference to orthogonal axes X, Y, and Z may be helpful, where X generally corresponds to a horizontal or lateral direction (e.g., left to right), Y generally corresponds to a vertical direction (e.g., above-below, or up-down), and Z corresponds to in-and-out (e.g., front-to-back, or in-and-out). Figure 2A The direction of the plane.

[0034] Figure 2B Various examples according to the present disclosure are shown. Figure 2A 11. A side plan view of an optical device of the present invention. The light-guiding optical element 130 may include a front surface 11F and a rear surface 11R, which may be parallel to each other, and wherein ambient lighting, for example from a scene, may primarily enter the light-guiding optical element 130 at the front surface 11F and exit the light-guiding optical element 130 at the rear surface 11R. For example, when the wearable device 110 is used, the aperture expander 16 may be disposed on, adjacent to, near, or embedded within the light-guiding optical element 130 at a position vertically below the conventional position of the user's eye 12. In this way, ambient light may enter the light-guiding optical element 130 along the optically clear line of sight area 27 in a manner such that the incident light is directed to the user's eye 12. As used herein, optically clear refers to a clearly reflecting optical structure or a clearly deflecting optical structure such that ambient light may pass through a portion of the light-guiding optical element 130 in an undisturbed manner and, for example, provide the user with an unobstructed view of their environment through the optical structure.

[0035] As described above, the aperture expander 16 may include a plurality of partially reflective parallel facets 19 configured to receive a plurality of light beams from a first guiding direction and expand the received light beams in a second output coupling direction 18. The expanded light beams 18 from the aperture expander 16 may, for example, exit the rear surface 11R at an exit angle 17 directed (e.g., directed to non-directed) to the user's eye 12. Alternatively, the center (e.g., vertical midpoint) of the aperture expander may be disposed below the line of sight region 27, while at least some of the aperture expanders 16 may extend into the line of sight region 27, based on, for example, the exit angle 17 and possibly other factors. In this way, an upper portion of the light-guiding optical element may include an optically clear line of sight region 27, wherein the upper portion includes, for example, a vertically separated portion above the midpoint of the aperture expander 16.

[0036] Figure 3AA front plan view of an optical system including a light guide optical element according to various examples of the present disclosure is shown. The optical device 102 may include a light guide optical element 130 configured to receive a collimated first image beam from an image projector 126, wherein the first image beam is provided (e.g., directly injected) into an input portion of an input coupler 14 and coupled at a shallow angle to enter the light guide optical element 130. In practice, the distance between the image projector 126 and the input coupler 14 may be very short. The injected image beam may be collimated for each point in an image, wherein different points in the image diverge when generated by the image projector 126. The collimated image beam from the image projector 126 may be injected into a portion of the light guide optical element 130 to generate a plurality of guided image beams 20 that propagate and reflect between a front surface 11F and a parallel rear surface 11R due to total internal reflection (TIR) ​​within the light guide optical element 130. For simplicity, the plurality of guided image beams 20 may correspond to a plurality of different points in the image field of the collimated first image beam and may have guided image beam central axes 21 corresponding to central rays within the plurality of guided image beams 20 .

[0037] The plurality of guided image beams 20 may continue to expand within the light guide optical element 130 and be directed to a reflector 22, which may be disposed at a second position 23, which may be on or near the peripheral edge of the light guide optical element 130. Alternatively, the reflector 22 may be located within a portion of the light guide optical element 130 that is away from the peripheral edge. The reflector 22 may include a mirror facing an interior portion of the light guide optical element 130, and may be located, for example, at a position vertically below the input coupler 14, as shown. The reflector 22 may be formed as a mirrored surface configured to completely reflect the plurality of guided image beams 20. In this manner, the reflector 22 may be configured to substantially reflect all incident image beams in the plurality of guided image beams 20. In other words, the reflector 22 may be substantially non-transmissive for the plurality of guided image beams 20. For example, the reflector 22 may include a coating configured to transmit scene light (e.g., light at different angles), but reflect guided image beams 20 that arrive at the reflector 22 within an expected angle. The reflector 22 may be disposed perpendicularly to the parallel front and rear surfaces 11F, 11R. Thus, any angular reference to the front surface 11F may be equivalent to a reference to the rear surface 11R. Alternatively, the reflector 22 may be disposed at an angle to the front surface 11F.

[0038] The plurality of guided image beams 20 may be reflected by the reflector 22 as a plurality of reflected guided image beams 24 having a reflected guided image beam central axis 30, which may correspond to a central ray of the plurality of reflected guided image beams 24 when the plurality of reflected guided image beams 24 leave the surface of the reflector 22. In this manner, a first beam angle 33 may be formed between the guided image beam central axis 21 and the reflected guided image beam central axis 30, wherein the first beam angle 33 may be greater than 90°. When the first beam angle 33 between the beam central axis 21 and the reflected beam central axis 30 is greater than 90°, the plurality of guided image beams 20 and the plurality of reflected guided image beams 24 may provide improved separation by being routed around other optical elements in the light guide optical element 130, thereby allowing the other optical elements to be larger and have improved light focusing capabilities compared to conventional light guide optical elements. Alternatively, the first beam angle 33 may be less than or equal to 90°. Here and elsewhere in the present disclosure, reflecting the plurality of guided image beams 20 by the reflector 22 to produce the plurality of reflected guided image beams 24 and continuously guiding the reflected image beams by total internal reflection (TIR) ​​within the light guide optical element 130 can be considered a type of in-plane folding of the plurality of guided image beams 20. The guided image beam central axis 21, the reflected guided image beam central axis 30, and the intersection (e.g., two lines and the intersection) of the guided image beam central axis 21 and the reflected guided image beam central axis 30 can form a plane about which the image beams are folded. After leaving the reflector 22, the plurality of reflected guided image beams 24 can be directed to a first aperture expander 26, which can be at least partially disposed within the light guide optical element 130.

[0039] The first aperture expander 26 can include a first plurality of partially reflective parallel facets 29 (e.g., surfaces or reflectors) that can be configured to receive the plurality of reflected guided image beams 24 and expand the plurality of reflected guided image beams 24 in a first dimension to produce a first plurality of expanded image beams 28, the first plurality of expanded image beams 28 having an expanded image guided beam central axis 32, which can correspond to a central ray of the plurality of expanded image beams 28 as the plurality of expanded image beams 28 exit the first aperture expander 26 (e.g., guide to guide). In this manner, a second beam angle 34 can be formed between the reflected beam central axis 30 and the first expanded beam central axis 32, wherein the second beam angle 34 can be less than 90°. Note that the plurality of partially reflective parallel facets 29 can be different from the reflector 22, which can be configured to substantially reflect all incident image beams in the plurality of guided image beams 20. The first plurality of partially reflective parallel facets 29 may be tilted at an angle that may be tilted relative to at least one of the parallel front surface 11F and a transverse plane (e.g., an XZ plane) perpendicular to the front surface 11F, or, for example, tilted relative to both. In this manner, the term "tilted" as applied to the plurality of partially reflective parallel facets may be used to refer to major exterior surfaces, such as the front surface 11F and the parallel rear surface 11R, which may be aligned with orthogonal X, Y, Z axes and may be at right angles to each other, as shown. Reference will be made to Figure 4 This tilting aspect is further briefly described. In this way, the first plurality of expanded image beams 28 can achieve greater and more uniform illumination. Alternatively, the first aperture expander 26 can have a plurality of partially reflective parallel facets 29 arranged perpendicular to the front surface 11F. The coating on the plurality of parallel facets in the first aperture expander 26 can efficiently reflect light at a predetermined angle. According to an example, when the second beam angle 34 is large (e.g., close to 90°), this can enable the production and use of optimal coatings for the plurality of parallel facets 29 in the first aperture expander 26, particularly in the case where, for example, the plurality of parallel facets 29 are tilted at an inclined angle and are not perpendicular to the front surface 11F. This may be due to the fact that the angular spectrum of the reflected beam is substantially separated from the angular spectrum of the transmitted beam. In addition, this can enable the use of polarization-insensitive coatings in which the Brewster angle can be outside the reflection angular spectrum, which can improve performance.

[0040] After exiting the first aperture expander 26, the first plurality of expanded image beams 28 may be directed to the second aperture expander 16, as briefly described above. The second aperture expander 16 may be at least partially disposed within the light-guiding optical element 130. The aperture expander 16 may include a second plurality of partially reflective parallel facets 19 configured to receive the first plurality of expanded image beams 28 from the first aperture expander 26 in a first direction and expand the expanded image beams 28 in a second direction that may be substantially orthogonal to the first direction.

[0041] As described, first aperture expander 26 may expand reflected guided image beam 24 in a first dimension (e.g., in a substantially lateral or X-axis direction) into a first plurality of expanded image beams 28, and then second aperture expander 16 may expand first plurality of expanded image beams 28 in a second dimension (e.g., in a substantially vertical or Y-axis direction) into a second plurality of expanded image beams 18, which may be emitted from rear surface 11R, for example, toward user's eyes 12. In this manner, first aperture expander 26 and second aperture expander 16 may cooperate to expand a version of the input beam in two dimensions (2D), thereby resulting in a two-dimensional (2D) expansion of the original aperture of image projector 126.

[0042] The planar shape of the first aperture expander 26 corresponds to a minimum cross-sectional size capable of appropriately expanding the reflected guided image beam 24 into a first plurality of expanded image beams, wherein the first aperture expander 26 may only contact an adjacent edge of the light-guiding optical element 130 at one point (e.g., with the adjacent edge of the light-guiding optical element 130). Figure 5 Advantages of such a minimally sized first aperture expander 26 may include minimizing the losses of reflected beams in less beneficial directions, thereby improving overall waveguide efficiency.

[0043] Figure 3B Various examples according to the present disclosure are shown. Figure 3A Side plan view of the optical device. Figure 3B Total internal reflection (TIR) ​​of the first plurality of expanded image beams 28 within the light guide optical element 130 is shown after exiting the first aperture expander 26. In each of the disclosed examples, a partially planar reflector 38 may be introduced into the light guide optical element 130 disposed between the front surface 11F and the rear surface 11R to provide better light mixing and produce more uniform illumination.

[0044] Figure 4Schematic isometric views of a portion of an aperture expander with partially reflective parallel facets according to various examples of the present disclosure are shown. As described above, the first aperture expander 26 may include a plurality of partially reflective parallel facets 29 and the second aperture expander 16 may include a second plurality of partially reflective parallel facets 19 that may be tilted at an angle that may be tilted relative to, for example, the front surface 11F and at least one of a lateral plane (e.g., an XZ plane) that may be perpendicular to the front surface 11F. As used herein, describing the partially reflective parallel facets as tilted may describe a plane for each of the partially reflective parallel facets that is oriented such that the plane of the partially reflective parallel facets is neither parallel nor perpendicular to any major axis or mutually parallel major external surfaces describing the light-guiding optical element 130. In particular, Figure 4 The planes of the exemplary facets 19 and 29 shown in the figure can be described as being partially tilted with reference to at least two or more of the X-axis, the Y-axis, and the Z-axis. Alternatively, the planes of the exemplary facets 29 can also be described as being tilted in a positive or negative direction about a plane perpendicular to the corresponding plane XY. R , YZ R or XZ R Although shown together, each partially reflective parallel facet 19 in the second aperture expander 16 may be disposed at a different tilt angle than the tilt angle of the partially reflective parallel facet 29 in the first aperture expander 26 .

[0045] Figure 5 11F shows a front plan view of an optical device including a light guide optical element according to various examples of the present disclosure. The light guide optical element 130 may include a light shielding member 36, which may be disposed on a portion of the front surface 11F ( Figure 2B ) and is configured to reduce scattering of the plurality of guided image light beams 20 from the front surface 11F. In addition, the shading member 36 can also prevent the scenery from being reflected into the user's eyes 12 through the reflector 22. In this way, the shading member 36 can be disposed on a portion of the front surface 11F adjacent to the reflector 22, wherein the shading member 36 can perform at least one of reducing scattering of the plurality of guided image light beams 20 and reducing the effect of ambient light on the reflector 22, which can improve the user's experience.

[0046] Figure 5 An example of a first aperture expander 26B having a first plurality of partially reflective parallel facets 29B and a second aperture expander 16B having a second plurality of partially reflective parallel facets 16B is shown, wherein either or both of the first aperture expander 26B and the second aperture expander 16B are Figure 3AThe corresponding elements in the illustrated example may have a larger area, which may improve the manufacturability of the light guide optical element 130. As described above, the same reference numerals in the drawings may indicate the same elements or functionally similar elements. Thus, for example, the first aperture expander 26B may be the same as the first aperture expander 26B. Figure 3A The first aperture expander 26 shown in FIG. 1 may be similar in some respects. In this example, after exiting the reflector 22, the plurality of reflected guided image beams 24 may be directed to a first aperture expander 26B, which may be at least partially disposed within the light guide optical element 130 and extend across the full width to an edge of the light guide optical element 130 (e.g., with the same aperture as FIG. 1 ). Figure 3A ). Multiple reflected guided image beams 24 can have reflected image beam central axes 30 corresponding to central rays within the multiple reflected guided image beams 24. First aperture expander 26B can be configured to receive multiple reflected guided image beams 24 and expand the multiple reflected image beams in a first dimension to produce a first plurality of expanded image beams 28B, the first plurality of expanded image beams 28B having expanded image beam central axes 32B, which can correspond to central rays of the multiple expanded image beams 28B when the multiple expanded image beams 28B leave the first aperture expander 26B. In this way, a third beam angle 34B between the reflected beam central axis 30 and the first expanded beam central axis 32B can be less than 90° but greater than the second beam angle 34( Figure 3A ). Figure 5 The example first aperture expander 26B shown in FIG. 2 has various advantages, including being simpler to manufacture and thus less expensive.

[0047] Figure 6 A front plan view of an optical device including a light-guiding optical element according to various examples of the present disclosure is shown. Figure 6 The optical device 102 shown in FIG. Figure 3A The optical device 102 shown in is similar in some respects. However, Figure 6 Different reflectors 22C are shown at different positions 23C as well as different orientations of the first aperture expander 26C and different orientations of the second aperture expander 16C as shown.

[0048] The optical device 102 may include a light guide optical element 130 configured to receive a collimated first image beam from an image projector, which is applied to an input portion of an input coupler 14 at a first position 15 located on or near a peripheral edge of the light guide optical element 130. In this manner, a collimated image beam from the image projector 126 is injected into a portion of the light guide optical element 130, generating a plurality of guided image beams 20 due to total internal reflection (TIR) ​​between the parallel front and rear surfaces 11F, 11R.

[0049] The plurality of guided image beams 20 may continue to propagate within the light guide optical element 130 and be directed to a reflector 22C, which may be disposed at or near the peripheral edge of the light guide optical element at a fourth position 23C at or near the peripheral edge of the light guide optical element 130. Thus, the reflector 22C may be located near the peripheral edge of the light guide optical element 130 without overlapping the peripheral edge. As previously described, this is not considered to be limiting. In this example, the reflector 22C may be a mirror that faces an inner portion of the light guide optical element 130 and is disposed adjacent to the peripheral edge of the light guide optical element 130, for example, at a position 23C that may be vertically above the input coupler 14. The reflector 22C may be formed as a mirrored surface configured to completely reflect the plurality of guided image beams 20. The reflector 22C may be disposed perpendicular to the front surface 11F. Alternatively, the reflector 22C may be disposed at an angle to the front surface 11F. The plurality of guided image beams 20 may be reflected by the reflector 22C into a plurality of reflected guided image beams 24C having a reflected beam central axis 30C which may correspond to a central ray of the plurality of reflected guided image beams 24C when the plurality of reflected guided image beams 24C leave the surface of the reflector 22C.

[0050] The plurality of reflected guided image beams 24C, after exiting the reflector 22C, may be directed to a first aperture expander 26C, which may be at least partially disposed within the light-guiding optical element 130. The plurality of reflected guided image beams 24C may have reflected image beam central axes 30C corresponding to central rays within the plurality of reflected guided image beams 24. The first aperture expander 26C may include a first plurality of partially reflective parallel facets 29C, which may be configured to receive the plurality of reflected guided image beams 24C and expand the plurality of reflected guided image beams 24C in a first dimension to produce a first plurality of expanded image beams 28C, the first plurality of expanded image beams 28C having expanded image beam central axes 32C, which may correspond to central rays of the plurality of expanded image beams 28C as the plurality of expanded image beams 28C exit the first aperture expander 26C. Figure 6 The configuration shown in FIG. 3 can also provide that the fourth beam angle 34C between the reflected beam central axis 30C and the expanded image beam central axis 32C can be kept relatively large, similar to Figure 3A and can provide the same benefits. Figure 3A As with the example of the optical device 102 shown in , the first aperture expander 26C can have a plurality of partially reflective parallel facets 29C that can be tilted at an angle that can be tilted relative to at least one of the front surface 11F and a lateral plane (e.g., an XZ plane) perpendicular to the front surface 11F, or, for example, tilted relative to both.

[0051] The first plurality of expanded image beams 28C may be directed to the second aperture expander 16C after exiting the first aperture expander 26C, as briefly described above. The second aperture expander 16C may be at least partially disposed within the light-guiding optical element 130. The aperture expander 16C may include a second plurality of partially reflective parallel facets 19C configured to receive the first plurality of expanded image beams 28C from the first aperture expander in a first direction and expand the expanded image beams 28C in a second direction.

[0052] First aperture expander 26C may expand reflected guided image beam 24C in a first dimension, and second aperture expander 16C may subsequently expand first plurality of expanded image beams 28C in a second dimension, which may be emitted from rear surface 11R toward user's eyes 12. Thus, first aperture expander 26C and second aperture expander 16C may cooperate to expand a version of the input image beam in two dimensions (2D), thereby resulting in a two-dimensional expansion of the original aperture of image projector 126, for example.

[0053] The terms used herein are used only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that when used in this specification, the terms "includes", "comprising" and / or "comprising" specify the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or combinations thereof. In addition, the terms "upper", "upper", "lower", "lower", "above", "below", "left", "right", "front", "back" and the like are intended to be understood in the context of the representations described and shown above, so that the wearable device can have such an orientation with respect to the frame or with respect to various elements as supported by the frame or as shown in the accompanying drawings.

[0054] The corresponding structures, materials, actions, and equivalents of all means or step plus function elements (if any) in the following claims are intended to include any structure, material, or action for performing a function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for the purpose of illustration and description, but is not intended to be exhaustive or limited to the present invention in the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present invention. Various embodiments are selected and described in order to best illustrate the principles and practical applications of the present invention, and in order to enable other persons of ordinary skill in the art to understand the present invention in various embodiments with various modifications suitable for the particular use under consideration.

Claims

1. An optical device, comprising: a light-guiding optical element having a front surface and a rear surface that are parallel to each other; a reflector configured to receive a plurality of guided image beams and reflect a plurality of reflected guided image beams, the plurality of guided image beams and the plurality of reflected guided image beams propagating within the light guide optical element between the front surface and the rear surface; a first aperture expander having a first plurality of partially reflective parallel facets configured to expand the plurality of reflected guided image beams and provide a first plurality of expanded image beams; as well as A second aperture expander having a second plurality of partially reflective parallel facets is configured to expand the first plurality of expanded image beams and provide a second plurality of expanded image beams.

2. The optical device according to claim 1, in, The plurality of guided image beams have guided image beam central axes, wherein the plurality of reflected guided image beams have a reflected guided image beam central axis, and Wherein, an angle between a central axis of the guided image light beam and a central axis of the reflected guided image light beam is greater than 90°.

3. The optical device according to claim 1, wherein: The reflector is at least one of the following: disposed perpendicular to the front surface; and is disposed on the peripheral edge of the light-guiding optical element, The reflector is configured to completely reflect the received plurality of guided image light beams.

4. The optical device according to claim 1, further comprising: an input coupler configured to receive the collimated first image beam from the image projector and output the plurality of guided image beams propagating within the light guide optical element between the front surface and the rear surface, wherein the input coupler is arranged one of: adjacent to one of the front surface and the rear surface and at least partially embedded in the light-guiding optical element, and The input coupler is one of a prism, a diffraction element, a reflection element or a holographic element.

5. The optical device according to claim 4, in, The reflector is a mirror facing the inner portion of the light-guiding optical element and disposed adjacent to the peripheral edge of the light-guiding optical element in one of the following positions: vertically below the input coupler, and Vertically above the input coupler.

6. The optical device according to claim 1, in, the first plurality of partially reflective parallel facets being inclined at a first angle, the first angle being one of angles inclined relative to at least one of the front surface and a lateral plane perpendicular to the front surface; as well as The second plurality of partially reflective parallel facets are inclined at a second angle, wherein the second angle is one of angles inclined relative to at least one of the front surface and a lateral plane perpendicular to the front surface.

7. The optical device according to claim 6, wherein: At least one of the first plurality of partially reflective parallel facets and the second plurality of partially reflective parallel facets includes an angle selective coating.

8. The optical device according to claim 1, in, The upper portion of the light guide optical element includes an optically clear sight area, and Wherein, the second aperture expander is arranged vertically below the line of sight area.

9. The optical device according to claim 1, in, The first aperture expander is configured to expand the plurality of reflected guided image beams in a first dimension, the second aperture expander is configured to expand the first plurality of expanded image beams in a second dimension, and the first dimension and the second dimension are substantially orthogonal to each other.

10. The optical device according to claim 1, further comprising: A shading member disposed on a portion of the front surface adjacent to the reflector, the shading member being configured to perform at least one of the following: reducing scatter of the plurality of guided image beams, and The influence of ambient light on the reflector is reduced.

11. The optical device according to claim 1, wherein: The second plurality of expanded image light beams are configured to emerge from the rear surface.

12. An optical system comprising: a light-guiding optical element having a front surface and a rear surface that are parallel to each other; an image projector configured to generate a collimated first image beam based on a digital image, wherein the collimated first image beam is collimated to infinity; an input coupler configured to receive the collimated first image beam and output a plurality of guided image beams within the light guide optical element, the plurality of guided image beams propagating between the front surface and the rear surface; a reflector configured to receive a plurality of guided image light beams and to reflect a plurality of reflected guided image light beams, the plurality of guided image light beams propagating within the light guide optical element between the front surface and the rear surface; a first aperture expander having a first plurality of partially reflective parallel facets configured to expand the plurality of reflected image beams in a first dimension and provide a first plurality of expanded image beams; and A second aperture expander having a second plurality of partially reflective parallel facets is configured to expand the first plurality of expanded image beams in a second dimension and provide a second plurality of expanded image beams configured to emerge from the rear surface.

13. The optical system according to claim 12, in, The input coupler is disposed one of: adjacent to one of the front surface and the rear surface and at least partially embedded within the light-guiding optical element, and The input coupler is one of a prism, a diffraction element, a reflection element or a holographic element.

14. The optical system of claim 12, further comprising: a frame configured to support the image projector and at least a portion of the light guide optical element, the frame configured to be worn on a portion of a user's head adjacent to the user's eyes; an optical engine configured to receive the digital image and operate the image projector; as well as A controller is configured to operate the optical engine and the projector.

15. The optical system according to claim 12, in, The plurality of guided image beams have guided image beam central axes, wherein the plurality of reflected guided image beams have a reflected guided image beam central axis, and Wherein, an angle between a central axis of the guided image light beam and a central axis of the reflected guided image light beam is greater than 90°.

16. The optical system according to claim 12, in, The reflector is a mirror facing the inner portion of the light-guiding optical element and arranged adjacent to the peripheral edge of the light-guiding optical element as one of the following: vertically below the input coupler, and Vertically above the input coupler, The reflector is configured to completely reflect the received plurality of guided image light beams.

17. The optical system according to claim 12, in, The first aperture expander comprises a plurality of partially reflective parallel facets, the facets being inclined at one of the following angles: is inclined relative to at least one of the front surface and a transverse plane perpendicular to the front surface, and perpendicular to the front surface.

18. The optical system according to claim 17, wherein: At least one of the first plurality of partially reflective parallel facets and the second plurality of partially reflective parallel facets includes an angle selective coating.

19. The optical system according to claim 12, in, The upper portion of the light guide optical element includes an optically clear sight area, and Wherein, the second aperture expander is arranged vertically below the line of sight area.

20. The optical system of claim 12, further comprising: a partially planar reflector disposed within the light-guiding optical element parallel to the front surface; as well as A shading member disposed on a portion of the front surface adjacent to the reflector, the shading member being configured to perform at least one of the following: reducing scatter of the plurality of guided image beams, and Reduce the effect of ambient light on the reflector.

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