Open-ended auger waveguide

Abstract

This specification describes an optical waveguide comprising a pair of principal surfaces and an aperture configured to receive an input beam. The waveguide further includes a first set of facets arranged along a first axis and configured to reflect the input beam along a second axis. The waveguide further includes an aperture conforming to the aperture, configured to block light rays from outside the aperture from entering the optical waveguide. The first dimension of the aperture (and thus the aperture) corresponds to the pitch of the first set of facets, and the second dimension of the aperture (and thus the aperture) corresponds to the configuration of the waveguide corresponding to the second axis. By using the aperture, overexposure of the waveguide can be minimized, thereby minimizing non-uniformity of the projected image.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 469,577, filed on May 30, 2023. The entire disclosure of U.S. Provisional Application No. 63 / 469,577 is incorporated herein by reference.

Background Art

[0002] Unless otherwise stated herein, the materials described in this section are not prior art to the claims of this application and are not admitted to be prior art merely because they are included in this section.

[0003] 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.

[0004] In some optical waveguides, a homogenizer (also called a mixer) is disposed between the major surfaces of the waveguide. Such a homogenizer can mix weak light rays and strong light rays in the waveguide and enhance the uniformity of light. Further, the homogenizer can reduce the entrance pupil, enabling the projector to be miniaturized. Although the homogenizer can provide the above advantages, when light enters the waveguide through an aperture smaller than what the mixer can tolerate, non - uniformity is also introduced.

Summary of the Invention

[0005] This specification describes an optical waveguide with an aperture diaphragm. The optical waveguide includes a pair of parallel principal surfaces and an aperture configured to receive an input beam. The aperture has a first dimension. The optical waveguide further includes a coupling input element configured to receive the input beam from the aperture and couple the input beam to the optical waveguide. The optical waveguide further includes a first set of facets positioned between the principal surfaces along a first axis and configured to receive the input beam from the coupling input element and reflect the input beam at least partially. The optical waveguide further includes a diaphragm configured to block light rays from outside the aperture from entering the optical waveguide. The first dimension corresponds to the pitch of the first set of facets.

[0006] This specification also describes the apparatus. The apparatus includes a projector configured to generate an input beam. The apparatus further includes the aforementioned optical waveguide. Note that the aperture of the apparatus may be located at the exit of the display system (e.g., on the outer surface of the projector) instead of on or in part of the optical waveguide (e.g., on the inlet of the optical waveguide).

[0007] The above summary is illustrative and not intended to limit in any way. Further embodiments, features, and characteristics beyond those described above will become apparent by reference to the drawings and the following detailed description. In the drawings, similar reference numerals indicate the same or functionally similar elements. [Brief explanation of the drawing]

[0008] [Figure 1] An example of a system including an optical waveguide with an aperture diaphragm according to each embodiment of the present disclosure is shown. [Figure 2] An example of an optical waveguide including an aperture diaphragm according to each embodiment of the present disclosure is shown. [Figure 3] Another diagram of the optical waveguide shown in Figure 2, relating to each embodiment of this disclosure, is shown. [Figure 4A]Another diagram of the optical waveguide in Figure 2, equipped with a single homogenizer, according to each embodiment of the present disclosure is shown. [Figure 4B] Another diagram of the optical waveguide in Figure 2, which includes two homogenizers, is shown for each embodiment of the present disclosure. [Figure 5A] This illustrates the excessive illumination caused by light entering outside the first dimension of the aperture of the optical waveguide according to each embodiment of the present disclosure. [Figure 5B] This illustrates the excessive illumination caused by light entering outside the second dimension of the aperture of the optical waveguide according to each embodiment of the present disclosure. [Modes for carrying out the invention]

[0009] The following description includes numerous specific details, such as particular structures, components, materials, dimensions, processes, and techniques, in order to provide an understanding of each embodiment of this application. However, it will be apparent to those skilled in the art that each embodiment of this application can be carried out without these specific details. In other instances, well-known structures or processes are not described in detail to avoid obscuring this application.

[0010] As will be described in more detail below, the system and method relating to this disclosure can be used to implement wearable devices such as myopia displays and / or smart glasses. This system can efficiently provide users with high-quality optical information in each application.

[0011] Figure 1 shows a block diagram of an example of an optical system 100 including an optical waveguide with an aperture diaphragm. The optical system 100 may include two or more devices or components. The optical system 100 can generally be implemented as a hybrid system including each electronic element, optical element, and electro-optical element. As will be described in more detail below, the optical system 100 may include one or more wearable devices 102, such as myopia displays or smart glasses, that are worn on or around the user's head and can transmit optical information to one or both of the user's eyes.

[0012] The wearable device 102 may include a controller 104 with memory 106, which may be configured to, for example, send and receive electrical signals with each other element in the optical system 100, process and provide information by executing program instructions stored in memory 106, operate the wearable device 102, or interact with other systems outside the wearable device 102. The controller 104 may include a microcontroller, a processor, each individual component, a programmable logic device, and / or each interface circuit that can access memory 106, and memory 106 may be removable, replaceable, programmable, and reprogrammable to update instructions to the controller 104.

[0013] The wearable device 102 may further include a power management module 108 having a battery 110, the power management module 108 may be configured to charge, discharge, and monitor the power usage of the battery 110. Each element of the wearable device 102 may receive power from the battery 110, and this may include, for example, a controller 104, one or more image projectors 112 (e.g., projection optics, or PODs), and a graphics engine 114 having one or more digital images 116.

[0014] Each image projector(s) may be configured to generate a collimated image beam based on a digital image(s)116. The collimated image beam may be an illumination representation of a digital image having an image field that is a two-dimensional representation of a digital image based on a single graphic image (e.g., a still image) or a sequence of graphic images (e.g., a video). The collimated image beam can be collimated up to infinity.

[0015] The wearable device 102 may also include one or more light guide optical elements 118 (e.g., LOE, also called waveguide WG, waveguide with aperture diaphragm) made of a transparent material configured to receive and propagate light, allowing light to enter and exit various external and internal surfaces of the light guide optical elements 118. For example, the transparent material containing the light guide optical elements 118 may include optical glass or other suitable materials that are transformed into complex optical structures using processes including coating, stacking, slicing, polishing, and molding of the transparent material. This process may include adding partially reflective or fully reflective materials, such as mirror coatings. Similarly, this process may also include adding partially opaque or fully opaque materials, such as light covers for blocking light.

[0016] The graphics engine 114 can be coupled to an image projector(s) 112 and a light guide optical element(s) 118. The graphics engine 114 can be configured to directly operate the image projector(s) 112 according to instructions from the controller 104. For example, the graphics engine 114 can provide graphics processing to a digital image before the illuminated representation of the digital image is projected by the image projector(s) 112.

[0017] The wearable device 102 may also include a frame 120 (e.g., a structure) for supporting and holding one or more elements within the wearable device 102. For example, the frame 120 may support and hold a first image projector 112a in a position adjacent to a first light guide optical element 118a. Similarly, the frame 120 may support and hold a second image projector 112b in a position adjacent to a second light guide optical element 118b. Thus, the frame 120 may support and hold one or more image projectors 112 and one or more light guide optical elements 118 on or around the user's head. In this specification, each element is referred to with respect to its orientation relative to one another. Such references may also include references to each element of the wearable device 102 when supported by the frame 120, or to a coordinate system (e.g., X-axis, Y-axis, Z-axis).

[0018] The optical system 100 may also include a host computer 122 which may include a processor 124 configured to read and execute operations based on instructions 126 stored in a computer-readable medium 128. The instructions 126 may include at least several instructions provided to the controller 104 and stored in memory 106. The host computer 122 can communicate with one or more elements of the wearable device 102 via a signal and power bus 130. In this way, the host computer 122 can provide power to charge the battery 110, provide instructions to the controller 104 and each of the other elements of the wearable device 102, receive status from them, and provide digital image data to the graphics engine 114.

[0019] Figure 2 shows an example of an optical waveguide with an aperture diaphragm (hereinafter referred to as waveguide 200). Waveguide 200 may be one of the optical guide elements 118. A three-dimensional Cartesian coordinate system (e.g., X-axis, Y-axis, Z-axis) is shown. For clarity, the same coordinate system is used throughout. The coordinate system used (e.g., axes and directions) can be changed without departing from the scope of this disclosure.

[0020] An input beam from one of the image projector(s) 112 (not shown) enters the waveguide 200 through the aperture 202. In the illustrated example, the aperture 202 is disposed on a major surface (e.g., one of two major surfaces) of the waveguide 200. In some embodiments, the aperture 202 can be disposed on other surfaces or objects (e.g., a coupling input prism).

[0021] A diaphragm 216 is provided around the aperture 202. The diaphragm 216 can be configured to prevent light rays outside the aperture 202 from entering the waveguide 200.

[0022] The input beam propagates towards the first set of facets 204 through total internal reflection (TIR) between the major surfaces of the waveguide 200. The first set of facets 204 can be perpendicular or oblique to the outer surface of the waveguide 200 and is configured to reflect the input beam at least partially towards the second set of facets 206. The beam reflected by the first set of facets 204 propagates through TIR between the major surfaces between the first set of facets 204 and the second set of facets 206. The second set of facets 206 can be oblique to the outer surface of the waveguide 200 and is configured to reflect the beam from the first set of facets 204 at least partially outside the waveguide 200 (e.g., in the direction of the eye box). To generate a uniform image, the cross-section of the waveguide 200 can be fully illuminated.

[0023] One or more homogenizer(s) 208 can be disposed between the first set of facets 204 and the second set of facets 206. In some embodiments, the homogenizer(s) 208 can be disposed in the same region (e.g., not between them) as the first set of facets 204 or the second set of facets 206.

[0024] The homogenizer(s) 208 can be any type of optical homogenizer configured to improve the uniformity of illumination. For example, the homogenizer(s) 208 can include a semi-reflective surface, a partially transmissive surface, or a partial planar reflector as a film (e.g., a partially reflective dielectric coating) added within the waveguide 200. The homogenizer(s) 208 can effectively fill the illumination gaps within the waveguide 200 by splitting the beam passing through the waveguide 200.

[0025] The input beam generally propagates parallel to the Y-axis from the coupling input element 210 (e.g., a mirror or prism) towards the first set of facets 204 (these can be reflected via TIR in the Y-Z plane but generally proceed in a direction parallel to the Y-axis). When reflected by the first set of facets 204, the reflected input beam generally propagates parallel to the X-axis (these can be reflected via TIR in the X-Z plane but generally proceed in a direction parallel to the X-axis). When reflected by the second set of facets 206, the beam generally propagates parallel to the Z-direction (e.g., the direction out of the waveguide 200). The propagation direction can be different at an angle with respect to the axis without departing from the scope of the present disclosure.

[0026] As used herein, each set or group of facets can include a plurality of planar, parallel to each other, and partially reflective optical elements (e.g., facets) spaced apart from each other. Thus, each facet of each group is parallel to each other and can be arranged at the same vertical or tilt angle. Also, the facets described herein can include an angle-selective coating and can be controlled to have multiple states (e.g., on / off) or to vary the reflectivity and / or transmittance levels of each facet or a cooperative set of facets within the structure.

[0027] Returning to the opening 202, the opening 202 is generally rectangular and has a first dimension 212 and a second dimension 214. The opening 202 may be surrounded by a diaphragm 216. Furthermore, the diaphragm 204 has an internal opening that can fit into the opening 202. In other words, the diaphragm 216 may have first and second internal dimensions that fit / match the first dimension 212 and the second dimension 214. In some embodiments, the dimensions of the internal opening of the diaphragm 216 may be slightly smaller than the first dimension 212 and the second dimension 214. The external dimensions of the diaphragm 216 can be modified without departing from the scope of this disclosure.

[0028] Figure 3 shows an example of waveguide 200 viewed from a different perspective than in Figure 2. The illustrated example is shown from a similar direction (for example, perpendicular to the XY plane), but rotated for clarity.

[0029] The illustrated example shows a projected aperture 300 and a projected aperture 302. The projected aperture 300 and projected aperture 302 are not actually in the illustrated positions, but are projected from the aperture 202 and aperture 216 to illustrate the effect of the sizes of the aperture 202 and aperture 216. The first length 304 in the X direction of the projected aperture 202 corresponds to the first dimension 212 of the aperture 202.

[0030] The first length 304 and the first dimension 212 correspond to the pitch of the first set of facets 204. For example, the first dimension 212 may be linearly related to the pitch of the first set of facets 204. The pitch of the first set of facets 204 may be the distance 306 between each adjacent facet in the direction perpendicular to the facets (e.g., the closest distance between them). The pitch (e.g., distance 306) may be constant between each facet of the first set of facets 204, or it may vary between the facets 204 of the first set. In either case, the first dimension 212 is linearly related to each of one or more pitches within the first set of facets 204.

[0031] The projection aperture 302 covers the area outside the first length 304 of the projection aperture 300. Similarly, the aperture 216 blocks light rays outside the first dimension 212 (relative to the length 304) of the aperture 202 from entering the waveguide 200.

[0032] The homogenizer(s) 208 and the second set of facets 206 may be located on the left side of Figure 3. As described above, the first set of facets 204 can at least partially reflect the input beam received from the coupled input element toward the second set of facets 206 via the homogenizer(s) 208.

[0033] Figures 4A and 4B show examples of waveguide 200 with one or two homogenizers, respectively, from a different viewpoint than Figure 2. For example, Figures 4A and 4B are viewed along an axis perpendicular to the XZ plane.

[0034] The examples in Figure 4A or Figure 4B may be used separately or in combination with the illustrated example in Figure 3. The waveguide 200 in Figure 4A includes a first homogenizer 208a positioned between two main surfaces 400. In the illustrated example, the first homogenizer 208a is equidistant between the two main surfaces 400. The waveguide 200 in Figure 4B includes a first homogenizer 208a and a second homogenizer 208b. In the illustrated example, the first homogenizer 208a and the second homogenizer 208b divide the space between the two main surfaces 400 into three equal parts. The configuration of the homogenizer(s) 208 between the main surfaces 402 can be modified without departing from the scope of this disclosure. In both illustrated examples, the second set of facets 206 may be positioned to the left of the homogenizer(s) 208.

[0035] To mitigate overexposure of the waveguide 200 along the illustrated axis (e.g., the X direction), the second dimension 214 of the aperture 202 is enclosed by the aperture 216. A projected aperture 300 and a projected aperture 302 are also illustrated (though with different dimensions than in Figure 3). The projected aperture 302 is shown to indicate the area blocked by the aperture 216. The second dimension 214 corresponds to the second length 402 of the projected aperture 300.

[0036] Note that in the example shown in Figure 4B, the aperture 216 is not necessarily required. A wider aperture of that dimension can better align the projector with the aperture 202, eliminating the need for the aperture 216.

[0037] Therefore, the first dimension 212 relates to the pitch of the first set of facets 204, and the second dimension 214 relates to the configuration of the waveguide 200 in the direction of the second set of facets 206 (e.g., the X direction). These configurations may include one or more of the thickness of the waveguide 200, the position of the homogenizer(s) 208, the field of view in the X direction, the angle of the second set of facets 206, or the angle of the coupling input element 210. Overexposure can be reduced by blocking the rays outside the first dimension 212 and the second dimension 214 with the aperture 216.

[0038] Figures 5A and 5B show examples of overexposure when the aperture 216 is not implemented. The example in Figure 5A shows overexposure caused by rays entering outside the first dimension 212. The example in Figure 5B shows overexposure caused by rays entering outside the second dimension 214. In both cases, divergent rays 500 (e.g., rays outside each dimension) enter the waveguide 200 and form an overexposure region 502. The overexposure region 502 corresponds to the region where the desired beam (e.g., beams within the first dimension 212 and the second dimension 214) overlaps with the reflection of the divergent rays 500.

[0039] In the example of Figure 5A, the divergent ray 500 is at least partially reflected by the first set of facets 204, forming an overexposed region 502. In the example of Figure 5B, the divergent ray 500 interacts with the homogenizer(s) 208 to form an overexposed region 502 (e.g., by superimposing it onto the desired beam). In both cases, the overexposed region 502 propagates through the waveguide 200 and moves away from the waveguide 200.

[0040] The aperture 216 can block the diverting rays 500 from entering the waveguide 200. This reduces the overexposed region 502. Thus, more uniform illumination can be achieved.

[0041] The terms used herein are for the sole purpose of describing specific embodiments and are not intended to limit the invention. Where used herein, the singular forms “a,” “an,” and “the” are intended to include the plural form unless otherwise explicitly indicated by the context. Where used herein, the terms “includes,” “comprises,” and / or “comprising” specify the presence of the described features, components, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, components, steps, operations, elements, components, and / or groups thereof. Furthermore, terms such as up, upward, down, downward, left, right, forward, and backward are intended to be understood in the context of the expressions described and illustrated above, so that the wearable device may take such orientations with respect to the frame, or each element supported by the frame, or as shown in the drawings.

[0042] In the following claims, where applicable, the corresponding structures, materials, actions, and equivalents of all means-plus-function or step-plus-function elements are intended to include any structures, materials, or actions for performing their function in combination with any other specifically claimed elements. The description of the present invention is presented for illustrative and explanatory purposes, but is not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Each embodiment has been selected and described in order to best illustrate the principles and practical applications of the invention and to enable those other skilled in the art to understand the invention in terms of various embodiments with various modifications to suit specific uses that may be conceived. [Examples]

[0043] Example 1: An optical waveguide comprising a pair of parallel principal surfaces; an aperture configured to receive an input beam and having a first dimension; a coupling input element configured to receive the input beam from the aperture and couple the input beam to an optical waveguide; a first set of facets positioned between the principal surfaces along a first axis and configured to receive the input beam from the coupling input element and at least partially reflect the input beam; and an aperture that fits the aperture and is configured to prevent rays from outside the aperture from entering the optical waveguide, wherein the first dimension of the aperture corresponds to the pitch of the first set of facets.

[0044] Example 2: The optical waveguide according to Example 1, wherein the aperture has a second dimension corresponding to the embodiment of the optical waveguide corresponding to the second axis.

[0045] Example 3: The optical waveguide according to Example 2, further comprising a second set of facets arranged between the principal surfaces along the second axis, wherein the first set of facets is configured to reflect the input beam at least partially to the second set of facets, and the second set of facets is configured to reflect the beam from the first set of facets at least partially out of the optical waveguide.

[0046] Example 4: The optical waveguide according to Example 3, further comprising a first homogenizer positioned parallel to the main surfaces between the main surfaces.

[0047] Example 5: The optical waveguide according to Example 4, wherein the second dimension of the aperture corresponds to the distance between the first homogenizer and one of the main surfaces.

[0048] Example 6: The optical waveguide according to Example 4 or 5, wherein the first homogenizer is located in the region between the first set of facets and the second set of facets.

[0049] Example 7: The optical waveguide according to Example 4 or 5, wherein the first homogenizer is located in the same region as the first set of facets or the second set of facets.

[0050] Example 8: The first homogenizer is located equidistant from each of the main surfaces of the optical waveguide according to any of Examples 4 to 7.

[0051] Example 9: An optical waveguide according to any one of Examples 4 to 8, further comprising a second homogenizer positioned between the first homogenizer and one of the main surfaces.

[0052] Example 10: An optical waveguide according to any of Examples 2 to 9, wherein the second dimension of the aperture is smaller than the first dimension of the aperture.

[0053] Example 11: An optical waveguide according to any one of the preceding examples, wherein the pitch of the first set of facets corresponds to the distance between adjacent facets of the first set of facets along the first axis.

[0054] Example 12: An optical waveguide according to any one of the preceding examples, wherein the aperture and the diaphragm are located on one of the main surfaces.

[0055] Example 13: An optical waveguide according to any one of the preceding examples, wherein the aperture includes an opening that fits the opening.

[0056] Example 14: The coupling input element is an optical waveguide as described in any one of the preceding examples, comprising a mirror or a prism.

[0057] Example 15: An apparatus comprising a projector configured to generate an input beam and an optical waveguide as described in any one of the preceding examples.

[0058] Example 16: Apparatus comprising an optical waveguide and a projector, wherein the optical waveguide comprises a pair of parallel principal surfaces, an aperture having a first dimension configured to receive an input beam, a coupling input element configured to receive the input beam from the aperture and couple the input beam to the optical waveguide, and a first set of facets positioned between the principal surfaces along a first axis and configured to receive the input beam from the coupling input element and reflect the input beam at least partially, the first dimension corresponding to the pitch of the first set of facets, the projector configured to generate an input beam, the projector comprising an aperture fitted to the aperture of the optical waveguide and configured to block light rays from outside the aperture of the optical waveguide from entering the optical waveguide.

Claims

1. A pair of parallel principal planes, An aperture having a first dimension is configured to receive an input beam, A coupling input element configured to receive the input beam from the aperture and couple the input beam to an optical waveguide, A first set of facets arranged between the main surfaces along a first axis and configured to receive the input beam from the coupling input element and to reflect the input beam at least partially, Includes an aperture that fits the aperture and is configured to block light rays from outside the aperture from entering the optical waveguide, An optical waveguide in which the first dimension of the opening corresponds to the pitch of the first set of facets.

2. The optical waveguide according to claim 1, wherein the opening has a second dimension corresponding to the configuration of the optical waveguide corresponding to the second axis.

3. The optical waveguide further includes a second set of facets arranged between the main surfaces along the second axis, The first set of facets is configured to reflect the input beam at least partially to the second set of facets, The optical waveguide according to claim 2, wherein the second set of facets is configured to reflect at least partially the beam from the first set of facets out of the optical waveguide.

4. The optical waveguide according to claim 3, further comprising a first homogenizer disposed between the main surfaces and parallel to the main surfaces.

5. The optical waveguide according to claim 4, wherein the second dimension of the opening corresponds to the distance between the first homogenizer and one of the main surfaces.

6. The optical waveguide according to claim 4 or 5, wherein the first homogenizer is located in the region between the first set of facets and the second set of facets.

7. The optical waveguide according to claim 4 or 5, wherein the first homogenizer is located in the same region as the first set of facets or the second set of facets.

8. The optical waveguide according to any one of claims 4 to 7, wherein the first homogenizer is equidistant from each of the main surfaces.

9. The optical waveguide according to any one of claims 4 to 8, further comprising a second homogenizer disposed between the first homogenizer and one of the main surfaces.

10. The optical waveguide according to any one of claims 2 to 9, wherein the second dimension of the aperture is smaller than the first dimension of the aperture.

11. The optical waveguide according to any one of the prior claims, wherein the pitch of the first set of facets corresponds to the distance between adjacent facets of the first set of facets along the first axis.

12. The optical waveguide according to any one of the prior claims, wherein the aperture and the diaphragm are arranged on one of the main surfaces.

13. The optical waveguide according to any one of the prior claims, wherein the aperture includes an opening that matches the opening.

14. The optical waveguide according to any one of the prior claims, wherein the coupling input element includes a mirror or a prism.

15. A projector configured to generate an input beam, An apparatus comprising an optical waveguide as described in any one of the prior claims.

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