Optical waveguide with split hole

Abstract

The waveguide includes a pair of major surfaces parallel to each other and an aperture configured to receive a plurality of light beams. The aperture includes a pair of sub-apertures that are coplanar and offset in one dimension. The waveguide also includes a first set of facets configured to receive the light beam from the aperture and at least partially reflect the light beam toward the second set of facets. The second set of facets is configured to receive the light beam from the first set of facets and at least partially reflect the light beam out of the light guide. The sub-aperture is offset in one dimension by an offset distance that corresponds to a projected distance along the one dimension that the light beam travels as it travels between the major surfaces between the first and second set of facets.

Description

Background Art

[0001] Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not to be considered prior art merely by virtue of their inclusion in this section.

[0002] 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 such as near-eye displays or smart glasses are typically limited in their ability to fully illuminate the cross-section of a waveguide used therein. If the cross-section is not fully illuminated, the image may be non-uniform (e.g., having artifacts or other undesirable artifacts). With a multi-axis expanding waveguide in which a light beam expands in two dimensions, illumination becomes increasingly difficult. Even when such a waveguide is fed with conjugate beams (e.g., dual beams), only a single beam can be transmitted by each facet in a first set of facets toward a second set of facets. The propagation of a single beam between the facets may result in insufficient illumination. What is needed is a solution to these and other problems. Summary of the Invention

[0004] An optical waveguide having split holes is described herein. The waveguide includes a pair of major surfaces parallel to each other. The waveguide further includes a hole that includes a pair of sub-holes aligned along a first axis, aligned along a second axis, and offset along a third axis. Each sub-hole is configured to receive one or more light beams. The waveguide further includes a first set of facets formed between the major surfaces, parallel to each other, equally spaced apart from each other, and configured to receive light beams from the hole and at least partially reflect the light beams toward a second set of facets. The waveguide further includes a second set of facets formed between the major surfaces, parallel to each other, equally spaced apart from each other, and configured to receive light beams from the first set of facets and at least partially reflect the light beams out of the optical waveguide. The sub-holes are offset by an offset distance that corresponds to the projected distance along the third axis that the light beam travels during a travel between the major surfaces after being reflected by the first set of facets.

[0005] An apparatus is also described herein. The apparatus includes a display system configured to generate a pair of one or more light beams (e.g., a pair of conjugate beams or a pair of non-conjugate beams). The apparatus further includes the optical waveguide discussed above.

[0006] The foregoing summary is illustrative only and is not intended to be limiting in any way. In addition to the above-described illustrative aspects, embodiments, and features, other aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. In the drawings, like reference numerals indicate like elements or elements that are functionally similar. Description of the Drawings

[0007] Figure 1 Examples of systems including an optical waveguide having a split hole in accordance with various examples of the present disclosure are shown.

[0008] Figure 2 Examples of optical waveguides including split holes in accordance with various examples of the present disclosure are shown.

[0009] Figure 3 Examples of beam propagation utilizing an optical waveguide including a split hole in accordance with various examples of the present disclosure are shown.

[0010] Figure 4 Three example holes within an optical waveguide having a split hole in accordance with various examples of the present disclosure are shown.

[0011] Figure 5 An example partial reflection of a beam by a first small plane of an optical waveguide having a split hole is shown.

[0012] Figure 6 Further shown is when the hole includes two adjacent sub-holes Figure 5 of the example partial reflection.

[0013] Figure 7 Further shown is when the hole includes separated sub-holes Figure 5 of the example partial reflection.

[0014] Figure 8 Examples of optical waveguides having virtual sub-holes in accordance with various examples of the present disclosure are shown.

[0015] Figure 9 Examples of optical waveguides having split holes for non-conjugate beams in accordance with various examples of the present disclosure are shown. Detailed Description

[0016] In the following description, numerous specific details are set forth, such as specific structures, components, materials, dimensions, processing steps, and techniques, in order to provide an understanding of the various embodiments of the present application. However, one of ordinary skill in the art will understand that the various embodiments of the present application may be practiced without these specific details. In other instances, well-known structures or processing steps have not been described in detail in order to avoid obscuring the present application.

[0017] As will be described in more detail below, wearable devices such as near-eye displays and / or smart glasses can be implemented by the systems and methods according to the present disclosure. The system can efficiently provide high-quality optical information to a user in various applications.

[0018] Figure 1 A block diagram of an example optical system 100 including an optical waveguide having a split aperture is shown. The optical system 100 can include two or more devices or components. The optical system 100 can generally be implemented as a hybrid system including various electronic, optical, and electro-optic elements. The optical device 102 can include one or more elements from the optical system 100. As will be described in more detail below, the optical system 100 can include a wearable device 110 (e.g., one or more near-eye displays or smart glasses) that can be worn on or around a user's head to deliver optical information to one or both of the user's eyes.

[0019] The wearable device 110 can include a controller 114 having a memory 116, where the controller 114 can be configured, for example, to: send electrical signals to and receive electrical signals from various other elements in the optical system 100; execute program instructions stored in the memory 116 to process and provide information; operate the wearable device 110; and interact with other systems external to the wearable device 110. The controller 114 can include a microcontroller, a processor, various discrete components, a programmable logic device, and / or various interface circuits that can access the memory 116, and the memory 116 can be removable, replaceable, programmable, and reprogrammable to update the instructions to the controller 114.

[0020] The wearable device 110 can also include a power management module 120 having a battery 122, where the power management module 120 can be configured to charge, discharge, and monitor the power usage of the battery 122. Various elements of the wearable device 110 can receive power from the battery 122, and the various elements include, for example, the controller 114, one or more image projectors 126 (e.g., projection optical devices or PODs (Projecting Optical Devices)), and a graphics engine 134 having one or more digital images 136.

[0021] 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 that 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.

[0022] The wearable device 110 may also include one or more light guide optical elements 130 (e.g., LOE (Light-guide Optical Element), also denoted as waveguide WG, waveguide with split holes), the light guide optical element including a transparent material configured to receive and propagate light, wherein light may enter and exit various outer and inner surfaces of the light guide optical element 130. For example, the transparent material including the light guide optical element 130 may include optical glass or other suitable materials, the use of which may include processes of coating, stacking, slicing, polishing, and shaping the transparent material into a complex optical structure. For example, the process may include adding a partially reflective material or a total reflective material (e.g., a mirror coating). Similarly, for example, the process may also include adding a partially opaque material or a completely opaque material (e.g., a light cover for blocking light).

[0023] The wearable device 110 may also include one or more graphics engines 134 coupled to the one or more image projectors 126 and the light guide optical elements 130. The graphics engine 134 may be configured to directly operate the image projector 126 under the guidance of the controller 114. For example, the graphics engine 134 may provide graphic processing of the digital image before the illuminated representation of the digital image is projected by the image projector 126.

[0024] The wearable device 110 may also include a frame 138 (e.g., structure) for supporting and holding one or more components in the wearable device 110. For example, the frame 138 may support and hold the first image projector 126a in a position adjacent to the first light guide optical element 130a. Similarly, the frame 138 may support and hold the second image projector 126b in a position adjacent to the second light guide optical element 130b. In this way, the frame 138 may support and hold a pair of one or two image projectors 126 and light guide optical elements 130 on or around the user's head. References are made herein to the orientation of various components relative to each other. As described in the associated drawings, such references may also include references to various components of the wearable device 110 when supported by the frame 138 or with reference to a three-dimensional (3D) reference (e.g., X, Y, Z axes).

[0025] 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 of the instructions provided to the controller 114 and stored in the memory 116. The host computer 170 may communicate with one or more components of the wearable device 110 via a signal and power bus 188. In this way, the host computer 170 may provide power to charge the battery 122, provide instructions to the controller 114 and various other components of the wearable device 110 and receive status from the controller 114 and various other components of the wearable device 110, and provide digital image data to the graphics engine 134.

[0026] Figure 2 An example of an optical waveguide 10 (hereinafter the waveguide 10) having split holes is shown. The waveguide 10 may be one of the light guide optical elements 130. A three-dimensional Cartesian coordinate system (e.g., X, Y, and Z axes) is shown. For clarity, the same coordinate system is used throughout the text. The coordinate system used may vary (e.g., axes and directions) without departing from the scope of the present disclosure.

[0027] A projector 126 (not shown) generates an image beam 4 (hereinafter the beam) that enters the waveguide 10 through a hole 18. The hole 18 may be located on the input prism 19. The axis is arranged such that the hole 18 is located in a plane parallel to the X-Z plane.

[0028] The light beam 4 propagates towards the first set of facets 14 via total internal reflection (TIR) between the parallel main surfaces of the waveguide 10. The first set of facets 14 can be inclined relative to the outer surface of the waveguide 10 and is configured to reflect the light beam 4 at least partially towards the second set of facets 6. The light beam 4 propagates between the first set of facets 14 and the second set of facets 6 via TIR between the parallel main surfaces. The second set of facets 6 can also be inclined relative to the outer surface of the waveguide 10 and is configured to reflect the light beam 4 out of the waveguide 10 towards the eye box 2 at least partially. To generate a uniform image, as discussed below, the cross-section of the waveguide 10 can be fully illuminated.

[0029] The light beam 4 generally propagates parallel to the Y-axis from the aperture 18 towards the first set of facets 14 (they can be reflected via TIR in the Y-Z plane but generally advance in a direction parallel to the Y-axis). When the light beam 4 is reflected by the first set of facets 14, they generally propagate parallel to the X-axis (they can be reflected via TIR in the X-Z plane but generally advance in a direction parallel to the X-axis). When the light beam 4 is reflected by the second set of facets 6, they generally propagate in the Z-direction (e.g., towards the eye box 2 out of the waveguide 10). The propagation direction can be angularly different from the axis without departing from the scope of the present disclosure. For example, the light beam 4 can propagate in any direction towards the first set of facets 14 and in any direction towards the second set of facets 6 after being reflected by the first set of facets 14.

[0030] As used herein, each set of facets or facet group can include a plurality of mutually parallel and partially reflective optical elements (e.g., facets) spaced apart from each other. Thus, each facet in the corresponding group can be parallel to each other and set at the same inclination 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 reflectivity and / or transmittance levels of each facet or a set of cooperating facets in the structure. The last facets in the structure (e.g., the terminal facets, the lowermost facet in the first set of facets 14, and the rightmost facet in the second set of facets 6) 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, for consistency, reduced complexity, and simpler construction, each facet can have the same partial reflectivity. Instead, each facet group can have multiple partial reflectivities (e.g., one or more of the facets can have different partial reflectivities), and / or the final facets can be partially mirrored.

[0031] Figure 3Shows an example of beam propagation within waveguide 10. Aperture 18 includes two sub-apertures (e.g., sub-aperture 18a and sub-aperture 18b) that are aligned with respect to the Y-axis and Z-axis but offset with respect to the X-axis. In other words, sub-aperture 18a and sub-aperture 18b are coplanar and parallel to the X-Z plane, but there is a gap between sub-aperture 18a and sub-aperture 18b with respect to the X-axis. Sub-aperture 18a and sub-aperture 18b are offset such that the centerlines of sub-aperture 18a and sub-aperture 18b (e.g., the dashed lines parallel to the Z-axis) are spaced apart by an offset distance 22. In some implementations, an absorbing material 20 can be disposed on aperture 18 between sub-aperture 18a and sub-aperture 18b (e.g., within the gap between sub-aperture 18a and sub-aperture 18b). In other implementations, sub-aperture 18a and sub-aperture 18b can be adjacent to each other without an absorber material 20 disposed between sub-aperture 18a and sub-aperture 18b. The offset distance 22 and whether an absorber material 20 can be used are further discussed below.

[0032] Each sub-aperture is configured to receive a beam of light (e.g., beam 12a for sub-aperture 18a and beam 12b for sub-aperture 18b). Beam 12a and beam 12b can be located at the centers of sub-aperture 18a and sub-aperture 18b, respectively, and at the center of the projection field. Aperture 18 can be located within waveguide 10 (e.g., waveguide 10 can extend through aperture 18), or aperture 18 can be located on an end of waveguide 10. Beam 12a and beam 12b can have an incident angle less than the critical angle of waveguide 10 and can propagate towards the first set of facets 14 parallel to the Y-axis via TIR and partially pass through (via partial reflectivity) the first set of facets 14. In some implementations, beam 12a and beam 12b can propagate in a direction not parallel to the Y-axis. Beam 12a and beam 12b can be a pair of beams or conjugate beams (e.g., including anti-reflected beams) and can be parallel or collimated. Thus, aperture 18 (and the first set of facets 14) can be configured to receive co-propagating pairs of beams spaced apart by an offset distance 22.

[0033] When the first set of facets 14 is tilted with respect to the outer surface of the waveguide (e.g., not perpendicular to the parallel main surface) and beam 12a and beam 12b are a pair of beams, each facet in the first set of facets 14 will reflect one of the pair of beams (the other beam will pass through). As will be further discussed below, the reflected beams (e.g., beam 16a and beam 16b) become a pair of beams due to the spacing of the first set of facets 14.

[0034] The waveguide 10 is configured to match the offset distance 22 with the projection distance along the main surface that the light beams 16a and 16b travel between the parallel main surfaces. The light beams 16a and 16b can propagate parallel to the X-axis via TIR towards a second set of facets 6 (not shown) and partially pass through the second set of facets 6. In some implementations, the light beams 16a and 16b can propagate in a direction not parallel to the X-axis. Since the light beams 16a and 16b form a double beam, the waveguide 10 can be fully illuminated.

[0035] Figure 4 Three examples of holes 18 (e.g., example 400, example 402, and example 404) that can be used within the waveguide 10 are shown. Cross-sectional views of the light beams 16a and 16b are shown for reference. The offset distance 22 between the centerlines of the sub-holes 18a and 18b corresponds to the projection distance along the main surface that one of the light beams 16a or 16b makes between the parallel main surfaces (e.g., the semi-reflection period). In other words, the offset distance 22 corresponds to a single "bounce" distance along the X-axis (if the light beams 16a and 16b propagate parallel to the X-axis).

[0036] In each of examples 400 to 404, the offset distance 22 is the same. In example 400, the sub-holes 18a1 and 18b1 have a relatively narrow width and a wide absorber material 20a. Such an implementation can enable the projector 126 to be small in width (e.g., along the X-axis). In example 402, the sub-holes 18a2 and 18b2 have a relatively wide width and a thinner absorber material 20b. In example 404, the sub-holes 18a3 and 18b3 have the maximum available width for a given offset distance 22. In other words, the sub-holes 18a3 and 18b3 are adjacent to each other with no absorber material between the sub-holes 18a3 and 18b3. The sub-holes 18a3 and 18b3 can together simulate a single hole. Such an implementation can achieve a higher projection power; however, the projector 126 may be larger in width (e.g., along the X-axis). The maximum hole width is typically twice the offset distance 22 (e.g., example 404).

[0037] Figure 5Shows an example of partial reflection of a light beam by a first set of facets 14 of waveguide 10. As discussed above, light beams 12a and 12b are received from an aperture 18 (not shown) by the first set of facets 14 via TIR. Light beams 12a and 12b are separated by an offset distance 22. The first set of facets 14 partially reflects light beams 12a and 12b to create light beams 16a1 and 16b1 and light beams 16a2 and 16b2. The spacing between the first set of facets 14 is such that light beams 16a1 and 16b1 overlap in the X-Y plane (e.g., they produce a double light beam towards the second set of facets 6), and light beams 16a2 and 16b2 overlap in the X-Y plane (e.g., they produce another double light beam towards the second set of facets 6). In other words, the light beam originating from one aperture has a "partner" conjugate to the light beam originating from another aperture to produce a uniform image. Without a one-to-one correspondence, uniqueness may not exist (and the image may be non-uniform).

[0038] Adjacent double light beams or overlapping light beams (e.g., 16a1, 16b1 and 16a2, 16b2) are separated by a separation distance 23. In other words, two adjacent facets in the first set of facets 14 create light beams 16a1 and 16b1, and the next two adjacent facets create light beams 16a2 and 16b2. Depending on the different angles of waveguide 10 and the spacing of the first set of facets 14, the separation distance 23 may be the same as or different from the offset distance 22.

[0039] Figure 6 Shows an example of Figure 5 when aperture 18 includes two adjacent sub-apertures (e.g., similar to example 404)

[0040] of partial reflection. The light beams are still offset by up to the offset distance 22, but are shown with corresponding illumination bands 600. Since the sub-apertures are adjacent (e.g., there is no absorber material 20 between the sub-apertures), and due to the spacing of the first set of facets 14, the reflections from the first set of facets 14 are fully illuminated (shown by adjacent illumination bands 600).

[0041] The width of light beam 34a may correspond to the width of aperture 18. The width of light beam 36a may be the same as the width of light beam 34a for uniform illumination. However, the width may vary without departing from the scope of the present disclosure.

[0042] Although the waveguide 10 can be fully illuminated in the illustrated example, the aperture 18 may be too wide (e.g., the width of the light beam 34a may require an overly large projector). Thus, there may be a trade-off between illumination and the size of the aperture 18 and / or the projector 126.

[0043] Figure 7 An example is shown when the aperture 18 includes separated sub-apertures (e.g., similar to Examples 400 and 402). Figure 5 Partial reflection of the example between the light beams 12a and 12b. The offset distance 22 between the light beams 12a and 12b is similar to Figure 6 that of the offset distance, but due to the thinner sub-aperture width, the width of the light beam 34b can be less than the width of the light beam 34a. Since the sub-apertures are separated (e.g., non-adjacent), the width of the light beam 34b is not fully illuminated. Since the width of the light beam 34b is not fully illuminated, the reflection from it may not be fully illuminated (as shown by the region 30b between the illumination bands 600). For uniform illumination, the width of the light beam 36c can be the same as the width of the light beam 34b. However, without departing from the scope of the present disclosure, the width can vary.

[0044] To fully illuminate the waveguide 10, a third set of facets 700 can be added. The third set of facets 700 can be parallel to the first set of facets 14 and can be staggered with the first set of facets 14. In other words, each facet in the first set of facets 14 can be equidistant from each facet in the third set of facets 700. As shown, the third set of facets 700 illuminates the region 30b. When the aperture 18 includes an absorber material, the third set of facets 700 can allow for full illumination. It should be noted that the aperture 18 in such an implementation is thinner than Figure 7 the aperture 18 of the illustrated example (e.g., 34b is thinner / smaller than 34a given the same offset distance 22). Design constraints can specify the total width of the aperture 18 that affects the sub-aperture width (assuming the offset distance 22 is fixed), and thus the width of the absorber material 20. Therefore, a smaller aperture 18 can benefit from the third set of facets 700.

[0045] Similarly, there may be a trade-off between full illumination and the size of the aperture 18 and / or the projector 126. Thus, the absorber material 20 can be any width including zero (e.g., adjacent sub-apertures).

[0046] Figure 8 An example of the waveguide 10 with virtual sub-apertures is shown. The effect of the illustrated example is the same as Figure 3Have the same effect. That is, the first set of facets 14 receive the parallel light beams 12a and 12b that are spaced apart by the offset distance 22. To this end, the incident light beam 800 is split into the light beams 12a and 12b. The splitting can occur in the waveguide 10 or in a separate waveguide attached to the waveguide 10.

[0047] The incident light beam 800 enters the waveguide 10 or the separate waveguide through the hole 18. In the example shown, the hole 18 is not split (e.g., it serves as a single hole). The incident light beam 800 can have an incident angle smaller than the critical angle of the waveguide 10 or other waveguides, and can be a double light beam or a conjugate light beam (as shown). Without departing from the scope of the present disclosure, the incident light beam 800 can also be a single light beam. The incident light beam 800 can propagate toward the beam splitter 802 parallel to the Y-axis via TIR and partially pass through (via partial reflectivity) the beam splitter 802. In some implementations, the incident light beam 800 can propagate in a direction not parallel to the Y-axis.

[0048] The beam splitter 802 allows a part of the incident light beam 800 to pass through as the light beam 12a and reflects a part of the incident light beam 800 as the light beam 804 toward the reflector 806 (e.g., along the X-axis). In some implementations, the light beam 804 can propagate in a direction not parallel to the X-axis. The reflector 806 reflects the light beam 804 as the light beam 12b.

[0049] Between the beam splitter 802 and the first set of facets 14 is the first virtual hole 808. Between the reflector 806 and the first set of facets 14 is the second virtual hole 810. The first virtual hole 808 and the second virtual hole 810 can be separated similarly to the sub-holes 18a and 18b. The beam splitter 802 and the reflector 806 can be configured such that the first virtual hole 808 and the second virtual hole 810 are adjacent.

[0050] The first virtual hole 808 and the second virtual hole 810 can be more abstract or more tangible. For example, when the beam splitter 802 and the reflector 806 are located within another waveguide, the first virtual hole 808 and the second virtual hole 810 can be located at the transition between the other waveguide and the waveguide 10. However, if the beam splitter 802 and the reflector 806 are located within the waveguide 10, the first virtual hole 808 and the second virtual hole 810 can be conceptual because there is no transition between the beam splitter 802 and the reflector 806 and the first set of facets 14.

[0051] Figure 9 An example of the waveguide 10 configured for the light beams 12a and 12b as non-conjugate (single) parallel light beams is shown. The hole 18 can be associated with Figure 3 and Figure 4The example in is configured similarly but with a reduced height (e.g., along the Z-axis). This is because a single beam may not require the full height of the waveguide. However, in some implementations, the aperture 18 can be full height (e.g., extending between parallel major surfaces). Either way, the projector 126 that generates the non-conjugate beam can be smaller than the projector 126 that generates the conjugate beam. Additionally, since the beam is a single beam, each facet in the first set of facets 14 may reflect only one of the beams 12a and 12b.

[0052] Differing from the above example, the first set of facets 14 can be perpendicular to the parallel major surfaces. Combining the spacing of the sub-apertures 18a and 18b and the spacing of the first set of facets 14 generates the beams 16a and 16b with opposite TIR phases. When the beams 12a and 12b are single beams, the perpendicular first set of facets 14 can cause the waveguide 10 to be fully illuminated.

[0053] It should also be noted that Figure 8 the structure of can also be applied to the example shown. For example, a beam splitter and a reflector can be used to generate a virtual aperture instead of the split aperture shown.

[0054] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present invention. As used herein, unless the context clearly dictates otherwise, the singular forms “(a)”, “(an)”, and “(the)” are also intended to include the plural forms. It should also be understood that when used in this specification, the terms “includes”, “comprises”, and / or “comprising” specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Additionally, the terms “above”, “upper”, “below”, “lower”, “on top”, “beneath”, “left”, “right”, “front”, “rear”, etc. are intended to be understood in the context of the representations described and shown above, such that the wearable device can have such an orientation with respect to the frame or with respect to the various elements supported by the frame or as shown in the drawings.

[0055] All structural, material, and act equivalents of the means or steps plus function elements (if any) in the claims are intended to include any structure, material, or act for performing the function in conjunction with other claimed elements that are particularly claimed. The description of the invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or to limit the invention to 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 invention. The various embodiments were chosen and described in order to best explain the principles of the invention and its practical application, and to enable others of ordinary skill in the art to understand the invention with various modifications that are suited to the particular use contemplated.

[0056] Example

[0057] Example 1: A waveguide comprising: a pair of main surfaces parallel to each other; holes including a pair of sub-holes aligned along a first axis, aligned along a second axis, and offset along a third axis, the sub-holes being configured to receive respective light beams; and a first set of facets and a second set of facets, wherein the first set of facets is formed between the main surfaces, includes facets parallel to each other and is configured to receive the light beam from the holes and at least partially reflect the light beam towards the second set of facets, and wherein the second set of facets is formed between the main surfaces, includes facets parallel to each other and is configured to at least partially reflect the light beam reflected by the first set of facets out of the waveguide, wherein the sub-holes are offset by an offset distance corresponding to the projected distance along the main surface that the light beam can travel when the light beam travels a distance between the main surfaces after being reflected by the first set of facets.

[0058] Example 2: The waveguide according to Example 1, wherein the facets in the first set of facets and the second set of facets are inclined with respect to the outer surface of the waveguide.

[0059] Example 3: The waveguide according to Example 1, wherein the facets in the first set of facets are perpendicular to the main surfaces.

[0060] Example 4: The waveguide according to any of the preceding examples, wherein the light beam propagates along the first axis to the first set of facets and passes through the first set of facets.

[0061] Example 5: The waveguide according to any of the preceding examples, wherein the light beam propagates to the second set of facets and passes through the second set of facets.

[0062] Example 6: The waveguide according to any of the preceding examples, wherein the distance between two facets in the first set of facets is configured such that a first light beam from a first sub-aperture in the sub-apertures and at least partially reflected by the first facet of the two facets overlaps with a second light beam from a second sub-aperture in the sub-apertures and at least partially reflected by the second facet of the two facets.

[0063] Example 7: The waveguide according to Example 6, wherein the overlapping light beams partially reflected by the two facets in the first set of facets are separated from other overlapping light beam pairs partially reflected by immediately adjacent facet pairs by a separation distance.

[0064] Example 8: The waveguide according to Example 7, wherein the separation distance is equal to the offset distance.

[0065] Example 9: The waveguide according to Example 7, wherein the separation distance is different from the offset distance.

[0066] Example 10: The waveguide according to any of the preceding examples, wherein the sub-apertures are adjacent to each other.

[0067] Example 11: The waveguide according to any of the preceding examples, wherein the sub-apertures have a gap therebetween along the third axis.

[0068] Example 12: The waveguide according to Example 11, further comprising an absorber disposed in the gap.

[0069] Example 13: The waveguide according to Example 11 or 12, wherein: the distance between two facets in the first set of facets is configured such that a first light beam from a first sub-aperture in the sub-apertures and at least partially reflected by the first facet of the two facets overlaps with a second light beam from a second sub-aperture in the sub-apertures and at least partially reflected by the second facet of the two facets; and the waveguide further comprises a third set of facets parallel to the first set of facets and interleaved therebetween.

[0070] Example 14: A device, comprising: a projector configured to generate a pair of parallel light beams; a waveguide including: a pair of main surfaces parallel to each other; a hole including a pair of sub-holes aligned along a first axis, aligned along a second axis, and offset along a third axis, the sub-holes being configured to receive respective light beams of the pair of parallel light beams; and a first set of facets and a second set of facets, wherein the first set of facets is formed between the main surfaces, includes facets parallel to each other, and is configured to receive light beams from the hole and at least partially reflect the light beams toward the second set of facets, and wherein the second set of facets is formed between the main surfaces, includes facets parallel to each other, and is configured to receive light beams from the first set of facets and at least partially reflect the light beams out of the waveguide, wherein the sub-holes are offset by an offset distance corresponding to a projected distance along the main surfaces that the light beams can travel when the light beams travel a distance between the main surfaces after being reflected by the first set of facets.

[0071] Example 15: The device according to Example 14, wherein the pair of parallel light beams includes a pair of parallel conjugate light beams.

[0072] Example 16: The device according to Example 15, wherein the facets in the first set of facets are inclined with respect to the outer surface of the waveguide.

[0073] Example 17: The device according to Example 14, wherein the pair of parallel light beams includes a pair of non-conjugate light beams.

[0074] Example 18: The device according to Example 17, wherein the facets in the first set of facets are perpendicular to the main surfaces.

[0075] Example 19: The device according to Example 17 or 18, wherein the hole has a height along the second axis that is less than the distance between the main surfaces.

[0076] Example 20: A waveguide includes: a pair of main surfaces that are parallel to each other; a hole configured to receive a light beam; a beam splitter configured to receive the light beam from the hole, transmit a part of the light beam as a first light beam towards a first set of facets, and reflect another part of the light beam towards a reflector; the reflector configured to receive the another part of the light beam from the beam splitter and reflect the another part of the light beam as a second light beam towards the first set of facets; and the first set of facets and a second set of facets, wherein the first set of facets is formed between the main surfaces, includes facets parallel to each other and is configured to receive the first light beam from the beam splitter and the second light beam from the reflector, and at least partially reflect the first light beam as a reflected first light beam towards the second set of facets and at least partially reflect the second light beam as a reflected second light beam towards the second set of facets, and wherein the second set of facets is formed between the main surfaces, includes facets parallel to each other, and is configured to receive the reflected first light beam and the reflected second light beam from the first set of facets, and at least partially reflect the reflected first light beam and the reflected second light beam out of the waveguide, wherein the beam splitter and the reflector are configured such that the second light beam is parallel to the first light beam and offset from the first light beam by an offset distance that corresponds to the projected distance along the main surface that the reflected first light beam and the reflected second light beam can travel when the reflected first light beam and the reflected second light beam travel a distance between the main surfaces.

[0077] Example 21: The waveguide according to Example 20, wherein the facets in the first set of facets and the second set of facets are inclined with respect to the outer surface of the waveguide.

[0078] Example 22: The waveguide according to Example 20, wherein the facets in the first set of facets are perpendicular to the main surfaces.

[0079] Example 23: The waveguide according to any one of Examples 20 to 22, wherein: the beam splitter and the reflector are disposed in a first waveguide; the first set of facets and the second set of facets are disposed in a second waveguide; and the first waveguide is attached to the second waveguide.

[0080] Example 24: The waveguide according to any one of Examples 20 to 23, wherein the first set of facets is configured such that the reflected first light beam from a facet in the first set of facets overlaps with the reflected second light beam from an adjacent facet in the first set of facets to create an overlapping reflected light beam.

[0081] Example 25: The waveguide according to Example 24, wherein the overlapping reflected beams are separated by the offset distance.

[0082] Example 26: The waveguide according to any one of Examples 20 to 25, wherein the offset distance is equal to the width of the hole along the axis.

[0083] Example 27: A device comprising: a projector configured to generate a light beam; a waveguide comprising: a pair of main surfaces parallel to each other; a hole configured to receive the light beam; a beam splitter configured to receive the light beam from the hole, transmit a part of the light beam as a first light beam towards a first set of facets, and reflect another part of the light beam towards a reflector; the reflector configured to receive the another part of the light beam from the beam splitter and reflect the another part of the light beam as a second light beam towards the first set of facets; and the first set of facets and a second set of facets, wherein the first set of facets is formed between the main surfaces, comprises facets parallel to each other and is configured to receive the first light beam from the beam splitter and the second light beam from the reflector, and at least partially reflect the first light beam as a reflected first light beam towards the second set of facets and at least partially reflect the second light beam as a reflected second light beam towards the second set of facets, and wherein the second set of facets is formed between the main surfaces, comprises facets parallel to each other, and is configured to receive the reflected first light beam and the reflected second light beam from the first set of facets, and at least partially reflect the reflected first light beam and the reflected second light beam out of the waveguide, wherein the beam splitter and the reflector are configured such that the second light beam is parallel to the first light beam and offset from the first light beam by up to an offset distance corresponding to the projected distance along the main surface that the reflected first light beam and the reflected second light beam can travel when the reflected first light beam and the reflected second light beam travel a journey between the main surfaces.

[0084] Example 28: The device according to Example 27, wherein the light beam comprises conjugate light beams.

[0085] Example 29: The device according to Example 28, wherein the facets in the first set of facets are inclined with respect to the outer surface of the waveguide.

[0086] Example 30: The device according to Example 27, wherein the light beam comprises non-conjugate light beams.

[0087] Example 31: The apparatus according to Example 30, wherein the facets in the first set of facets are perpendicular to the major surface.

[0088] Example 32: The apparatus according to Example 30 or 31, wherein the holes have a height along other axes that is less than the distance between the major surfaces.

Claims

1. A waveguide comprising: a pair of major surfaces, the pair of major surfaces being parallel to each other; an aperture comprising a pair of sub-apertures aligned along a first axis, aligned along a second axis, and offset along a third axis, the sub-apertures configured to receive corresponding light beams; and The first set of facets and the second set of facets, wherein the first set of facets is formed between the major surfaces, comprises facets parallel to each other and is configured to receive a light beam from the aperture and at least partially reflect the light beam toward the second set of facets, and wherein the second set of facets is formed between the major surfaces, comprises facets that are parallel to each other and are configured to at least partially reflect a light beam reflected by the first set of facets out of the waveguide, wherein the sub-apertures are offset by an offset distance corresponding to a projected distance along the major surfaces that the light beam can travel when traversing a distance between the major surfaces after being reflected by the first set of facets.

2. The waveguide according to claim 1, wherein Facets in the first and second sets of facets are inclined relative to an outer surface of the waveguide.

3. The waveguide according to claim 1, wherein The facets in the first set of facets are perpendicular to the major surface.

4. A waveguide according to any preceding claim, wherein The light beam propagates along the first axis to and through the first set of facets.

5. A waveguide according to any preceding claim, wherein The light beam propagates to and through the second set of facets.

6. A waveguide according to any preceding claim, wherein A distance between two facets in the first group of facets is configured such that a first light beam from a first sub-aperture in the sub-apertures, which is at least partially reflected by a first facet in the two facets, overlaps with a second light beam from a second sub-aperture in the sub-apertures, which is at least partially reflected by a second facet in the two facets.

7. The waveguide according to claim 6, wherein: Overlapping light beams partially reflected by the two facets in the first set of facets are separated from other overlapping light beam pairs partially reflected by immediately adjacent facet pairs by a separation distance.

8. The waveguide according to claim 7, wherein The separation distance is equal to the offset distance.

9. The waveguide according to claim 7, wherein: The separation distance is different from the offset distance.

10. A waveguide according to any preceding claim, wherein The sub-holes are adjacent to each other.

11. A waveguide according to any preceding claim, wherein The sub-holes have gaps between them along the third axis.

12. The waveguide of claim 11, further comprising an absorber disposed in the gap.

13. A waveguide according to claim 11 or 12, wherein: A distance between two facets in the first set of facets is configured such that a first light beam from a first sub-aperture of the sub-apertures at least partially reflected by a first facet of the two facets in the first set of facets overlaps a second light beam from a second sub-aperture of the sub-apertures at least partially reflected by a second facet of the two facets in the first set of facets; The waveguide further includes a third set of facets parallel to the first set of facets and interlaced between the first set of facets; and The distance between two facets in the third group of facets is configured such that a first light beam from a first sub-aperture in the sub-apertures, which is at least partially reflected by a first facet in the two facets in the third group of facets, overlaps with a second light beam from a second sub-aperture in the sub-apertures, which is at least partially reflected by a second facet in the two facets in the third group of facets.

14. A device comprising: a projector configured to generate a pair of parallel light beams; A waveguide, the waveguide comprising: a pair of major surfaces, the pair of major surfaces being parallel to each other; an aperture comprising a pair of sub-apertures aligned along a first axis, aligned along a second axis, and offset along a third axis, the sub-apertures being configured to receive respective ones of the pair of parallel light beams; and The first set of facets and the second set of facets, wherein the first set of facets is formed between the major surfaces, comprises facets parallel to each other and is configured to receive a light beam from the aperture and at least partially reflect the light beam toward the second set of facets, and wherein the second set of facets is formed between the major surfaces, includes facets that are parallel to each other, and is configured to receive a light beam from the first set of facets and at least partially reflect the light beam out of the waveguide, wherein the sub-apertures are offset by an offset distance corresponding to a projected distance along the major surfaces that the light beam can travel when traversing a distance between the major surfaces after being reflected by the first set of facets.

15. The device according to claim 14, wherein: The pair of parallel light beams includes a pair of parallel conjugate light beams.

16. The device according to claim 15, wherein: Facets in the first set of facets are inclined relative to an outer surface of the waveguide.

17. The apparatus according to claim 14, wherein: The pair of parallel light beams comprises a pair of non-conjugate light beams.

18. The apparatus according to claim 17, wherein: The facets in the first set of facets are perpendicular to the major surface.

19. The apparatus according to claim 17 or 18, wherein: The hole has a height along the second axis that is less than a distance between the major surfaces.

20. A waveguide comprising: a pair of major surfaces, the pair of major surfaces being parallel to each other; an aperture configured to receive a light beam; a beam splitter configured to receive the light beam from the aperture, pass a portion of the light beam as a first light beam toward the first set of facets, and reflect another portion of the light beam toward a reflector; the reflector configured to receive another portion of the light beam from the beam splitter and reflect the other portion of the light beam as a second light beam toward the first set of facets; as well as the first set of facets and the second set of facets, wherein the first set of facets is formed between the major surfaces, includes facets that are parallel to each other and is configured to receive a first light beam from the beam splitter and a second light beam from the reflector, and at least partially reflect the first light beam as a reflected first light beam toward the second set of facets and at least partially reflect the second light beam as a reflected second light beam toward the second set of facets, and wherein the second set of facets is formed between the major surfaces, includes facets that are parallel to each other, and is configured to receive the reflected first light beam and the reflected second light beam from the first set of facets, and at least partially reflect the reflected first light beam and the reflected second light beam out of the waveguide, wherein the beam splitter and the reflector are configured such that the second light beam is parallel to the first light beam and is offset relative to the first light beam by the following offset distance, wherein the offset distance corresponds to a projection distance along the main surface that the reflected first light beam and the reflected second light beam can travel when the reflected first light beam and the reflected second light beam travel a distance between the main surface.

21. The waveguide according to claim 20, wherein Facets in the first and second sets of facets are inclined relative to an outer surface of the waveguide.

22. The waveguide according to claim 20, wherein The facets in the first set of facets are perpendicular to the major surface.

23. A waveguide according to any one of claims 20 to 22, wherein: The beam splitter and the reflector are disposed in the first waveguide; The first set of facets and the second set of facets are disposed within a second waveguide; and The first waveguide is attached to the second waveguide.

24. A waveguide according to any one of claims 20 to 23, wherein The first set of facets is configured such that a reflected first light beam from a facet in the first set of facets overlaps a reflected second light beam from an adjacent facet in the first set of facets to create an overlapping reflected light beam.

25. The waveguide of claim 24, wherein: The overlapping reflected light beams are separated by the offset distance.

26. A waveguide according to any one of claims 20 to 25, wherein The offset distance is equal to the width of the hole along the axis.

27. An apparatus comprising: a projector configured to generate a light beam; A waveguide, the waveguide comprising: a pair of major surfaces, the pair of major surfaces being parallel to each other; an aperture configured to receive the light beam; a beam splitter configured to receive the light beam from the aperture, pass a portion of the light beam as a first light beam toward the first set of facets, and reflect another portion of the light beam toward a reflector; the reflector being configured to receive another portion of the light beam from the beam splitter and reflect the other portion of the light beam as a second light beam toward the first set of facets; and the first set of facets and the second set of facets, wherein the first set of facets is formed between the major surfaces, includes facets that are parallel to each other and is configured to receive a first light beam from the beam splitter and a second light beam from the reflector, and at least partially reflect the first light beam as a reflected first light beam toward the second set of facets and at least partially reflect the second light beam as a reflected second light beam toward the second set of facets, and wherein the second set of facets is formed between the major surfaces, includes facets that are parallel to each other, and is configured to receive the reflected first light beam and the reflected second light beam from the first set of facets, and at least partially reflect the reflected first light beam and the reflected second light beam out of the waveguide, wherein the beam splitter and the reflector are configured such that the second light beam is parallel to the first light beam and is offset relative to the first light beam by the following offset distance, wherein the offset distance corresponds to a projection distance along the main surface that the reflected first light beam and the reflected second light beam can travel when the reflected first light beam and the reflected second light beam travel a distance between the main surface.

28. The apparatus of claim 27, wherein: The light beam comprises a conjugate light beam.

29. The apparatus of claim 28, wherein: Facets in the first set of facets are inclined relative to an outer surface of the waveguide.

30. The apparatus of claim 27, wherein: The light beam comprises a non-conjugate light beam.

31. The apparatus of claim 30, wherein: The facets in the first set of facets are perpendicular to the major surface.

32. Apparatus according to claim 30 or 31, wherein The hole has a height along the other axis that is less than the distance between the major surfaces.

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