Optical waveguide with divided apertures

Abstract

The waveguide includes a pair of principal surfaces parallel to each other and an aperture configured to receive multiple 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 beams from the aperture and reflect the beams at least partially toward a second set of facets. The second set of facets is configured to receive beams from the first set of facets and reflect the beams at least partially toward the waveguide. The sub-apertures are offset in one dimension by an offset distance corresponding to the projection distance along one dimension through which the beam travels while it traverses one trip between the principal surfaces between the first and second sets of facets.

Description

Technical Field

[0001] Unless otherwise stated in this specification, the materials described in this section are not prior art with respect to the claims of this application and are not to be regarded as prior art by 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.

Background Art

[0003] Wearable optical devices such as near-eye displays or smart glasses often have limited ability to fully illuminate the cross-section of the waveguide used therein. If the cross-section is not fully illuminated, the image may be non-uniform (e.g., having banding or other undesirable artifacts). In a multi-axis expanding waveguide where the beam is expanded two-dimensionally, illumination becomes increasingly difficult. Even when such a waveguide is supplied with a conjugate beam (e.g., a dual beam), only a single beam can be transmitted by each facet within the first set of facets towards the second set of facets. Single beam propagation between sets of facets can result in insufficient illumination. What is needed are solutions to address problems such as these.

Summary of the Invention

[0004] An optical waveguide having a split aperture is described herein. The waveguide includes a pair of main surfaces that are parallel to each other. The waveguide also includes an aperture comprising a pair of sub-apertures aligned along a first axis, aligned along a second axis, and offset along a third axis. Each sub-aperture is configured to receive one or more beams. The waveguide further includes a first set of facets formed between the main surfaces, parallel to each other, equally spaced apart from each other, and configured to receive beams from the aperture and reflect the beams at least partially toward a second set of facets. The waveguide also includes a second set of facets formed between the main surfaces, parallel to each other, equally spaced apart from each other, and configured to receive beams from the first set of facets and reflect the beams at least partially toward the optical waveguide. The sub-apertures are offset by an offset distance corresponding to the projection distance along the third axis, during which the beam travels while traversing one trip between the main surfaces after being reflected by the first set of facets.

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

[0006] The above summary is illustrative and not intended to be limiting. Further embodiments, features, and characteristics beyond those described above will become apparent by referring to the drawings and the detailed description below. In the drawings, similar reference numerals indicate the same or functionally similar elements. [Brief explanation of the drawing]

[0007] [Figure 1] Examples of systems including optical waveguides having segmented apertures, according to various embodiments of this disclosure, are illustrated. [Figure 2] Examples of optical waveguides including segmented apertures, according to various embodiments of this disclosure, are illustrated. [Figure 3] This disclosure illustrates exemplary beam propagation using optical waveguides including segmented apertures, as described in various embodiments of this disclosure. [Figure 4] Three exemplary apertures in an optical waveguide having a segmented aperture are illustrated in various embodiments of the present disclosure. [Figure 5] This illustrates an exemplary partial reflection of a beam by a first facet of an optical waveguide having a split aperture. [Figure 6] The exemplary partial reflection in Figure 5, where the aperture includes two adjacent sub-apertures, is further illustrated. [Figure 7] The exemplary partial reflection shown in Figure 5, where the aperture includes a separate sub-aperture, is illustrated further. [Figure 8] Examples of optical waveguides having virtual sub-apers are illustrated by various embodiments of this disclosure. [Figure 9] Examples of optical waveguides having segmented apertures for non-conjugated beams are illustrated by various examples of this disclosure. [Modes for carrying out the invention]

[0008] In the following description, many specific details such as particular structures, components, materials, dimensions, processing steps, and techniques are described in order to provide an understanding of the various embodiments of this application. However, it will be understood by those skilled in the art that the various embodiments of this application can be practiced without these specific details. In other cases, well-known structures or processing steps are not described in detail in order to avoid obscuring this application.

[0009] For further details, wearable devices such as near-eye displays and / or smart glasses can be implemented by the systems and methods described in accordance with this disclosure. The systems can efficiently provide users with high-quality optical information in a variety of applications.

[0010] Figure 1 illustrates a block diagram of an exemplary optical system 100, which includes an optical waveguide with a split aperture. 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. An optical device 102 may include one or more elements from the optical system 100. For further detail below, the optical system 100 may include one or more wearable devices 110, such as near-eye displays or smart glasses, which may be worn on or around the user's head to transmit optical information to one or more of the user's eyes.

[0011] The wearable device 110 may include a controller 114 having a memory 116, which may be configured to operate the wearable device 110, for example, by executing program instructions stored in the memory 116 to transmit and receive electrical signals to and from various other elements within the optical system 100, process and provide information, and interact with other systems outside the wearable device 110. The controller 114 may include a microcontroller, a processor, various individual components, programmable logic devices, and / or various interface circuits that can access the memory 116, which may be removable, replaceable, programmable, and reprogrammable, to update instructions to the controller 114.

[0012] The wearable device 110 may also include a power management module 120 having a battery 122, which may be configured to charge, discharge, and monitor the power usage of the battery 122. Various elements of the wearable device 110, for example, including a controller 114, one or more image projectors 126 (e.g., projection optical devices, i.e., PODs), and a graphics engine 134 having one or more digital images 136, may receive power from the battery 122.

[0013] 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 illumination representation of a digital image having an image field that is a two-dimensional representation of the digital image, based on either a single graphical image (e.g., a still image) or a sequence of graphical images (e.g., a video). The collimated image beam may be collimated infinitely.

[0014] The wearable device 110 may also include one or more light guide optical elements 130 (e.g., LOE, also indicated as waveguide WG, waveguide with split apertures) comprising a transparent material configured to receive and propagate light, and light may enter and exit various outer and inner surfaces of the light guide optical elements 130. For example, the transparent material comprising the light guide optical elements 130 may include optical glass or other suitable material which is converted into a composite optical structure using a process which may include coating, laminating, slicing, polishing, and molding the transparent material. The process may include, for example, adding a partially reflective or totally reflective material such as a mirror coating. Similarly, the process may also include adding a partially opaque or completely opaque material, for example, a light cover for blocking light.

[0015] The wearable device 110 may also include one or more graphics engines 134 coupled to one or more image projectors 126 and light guide optical elements 130. The graphics engines 134 may be configured to directly operate the image projectors 126 under the direction of the controller 114. For example, the graphics engines 134 may provide graphics processing of the digital image before the projection of the illuminated representation of the digital image by the image projectors 126.

[0016] The wearable device 110 may also include a frame 138 (e.g., a structure) for supporting and holding one or more elements within the wearable device 110. For example, the frame 138 may support and hold a first image projector 126a in a predetermined position next to a first light guide optical element 130a. Similarly, the frame 138 may support and hold a second image projector 126b in a position next to a second light guide optical element 130b. Thus, the frame 138 may support and hold one or two pairs of image projectors 126 and light guide optical elements 130 on or around the user's head. References relating to the orientation of various elements relative to each other are made herein. Such references may also include references to various elements of the wearable device 110 when supported by the frame 138 or in relation to three-dimensional (3D) coordinates (e.g., X, Y, Z axes), as shown in the relevant drawings.

[0017] 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 several instructions provided to the controller 114 and stored in memory 116. The host computer 170 can communicate with one or more elements of the wearable device 110 via a signal and power bus 188. In this way, the host computer 170 can provide power to charge the battery 122, provide instructions to the controller 114 and various other elements of the wearable device 110, receive status from them, and provide digital image data to the graphics engine 134.

[0018] Figure 2 shows an example of an optical waveguide 10 having a split aperture (hereinafter referred to as waveguide 10). Waveguide 10 may be one of the optical guide elements 130. A three-dimensional Cartesian coordinate system (e.g., X, Y, and Z axes) is illustrated. For clarity, the same coordinate system is used throughout. The coordinate system used may change (e.g., axes and directions) without departing from the scope of this disclosure.

[0019] The projector 126 (not shown) generates an image light beam 4 (hereinafter referred to as the beam) that enters the waveguide 10 through the aperture 18. The aperture 18 can be located on the coupling prism 19. The axis is set such that the aperture 18 is in a plane parallel to the X-Z plane.

[0020] The beam 4 propagates between the parallel major surfaces of the waveguide 10 toward the first set 14 of facets via total internal reflection (TIR). The first set 14 of facets may be inclined with respect to the outer surface of the waveguide 10 and is configured to at least partially reflect the beam 4 toward the second set 6 of facets. The beam 4 propagates between the parallel major surfaces between the first set 14 of facets and the second set 6 of facets via TIR. The second set 6 of facets may also be inclined with respect to the outer surface of the waveguide 10 and is configured to at least partially reflect the beam 4 out of the waveguide 10 toward the eyebox 2. In order to generate a uniform image, the cross-section of the waveguide 10 can be fully illuminated as discussed below.

[0021] The beam 4 generally propagates from the aperture 18 toward the first set 14 of facets parallel to the Y axis (the beam 4 can be reflected via TIR in the Y-Z plane but generally travels in a direction parallel to the Y axis). When the beam 4 is reflected by the first set 14 of facets, the beam 4 generally propagates parallel to the X axis (the beam 4 can be reflected via TIR in the X-Z plane but generally travels in a direction parallel to the X axis). When the beam 4 is reflected by the second set 6 of facets, the beam 4 generally propagates parallel to the Z direction (e.g., out of the waveguide 10 toward the eyebox 2). The propagation direction may be angularly different from the axis without departing from the scope of the present disclosure. For example, the beam 4 may propagate in any direction toward the first set 14 of facets and, after being reflected by the first set 14 of facets, propagate in any direction toward the second set 6 of facets.

[0022] As used herein, each set or group of facets may comprise a plurality of spaced optical elements (e.g., facets) that are planar, parallel to each other, and partially reflective. Thus, each facet in each group may be parallel to each other and arranged at the same inclination angle. The facets described herein may also comprise angle-selective coatings that 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 the cooperative set of facets in the structure. The final facets in the structure (e.g., terminal facets, the furthest lower facet in the first set of facets 14, and the furthest right facet in the second set of facets 6) may be fully specular (e.g., not partially specular) to reflect any remaining illumination that may pass through the previous facets in the structure. Alternatively, each facet may have the same partial reflectivity for consistency, reduced complexity, and a simpler structure. Conversely, each group of facets may have multiple partial reflectances (for example, one or more of the facets may have different partial reflectances), and / or the final facet may be partially specular.

[0023] FIG. 3 illustrates an exemplary 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-apertures 18a and 18b are on the same plane, parallel to the X-Z plane, but have a gap between them with respect to the X-axis. Sub-apertures 18a and 18b are offset such that the centerlines of sub-apertures 18a and 18b (e.g., the dotted lines parallel to the Z-axis) are separated by an offset distance 22. In some implementations, absorber material 20 may be disposed on aperture 18 between sub-apertures 18a and 18b (e.g., within the gap between sub-apertures 18a and 18b). In other implementations, sub-apertures 18a and 18b may be adjacent to each other with no absorber material 20 disposed between them. The offset distance 22, and whether absorber material 20 can be used, will be further considered below.

[0024] Each sub-aperture is configured to receive a beam (e.g., beam 12a for sub-aperture 18a and beam 12b for sub-aperture 18b). Beams 12a and 12b can be centered at the centers of sub-apertures 18a and 18b, respectively, and at the center of the projected field. Aperture 18 may be within waveguide 10 (e.g., waveguide 10 may extend beyond aperture 18), or aperture 18 may be on an end of waveguide 10. Beams 12a and 12b can have an angle of incidence less than the critical angle of waveguide 10 and can propagate, via TIR, parallel to the Y-axis, partially through the first set of facets 14 (via partial reflectivity) towards the first set of facets 14. In some implementations, beams 12a and 12b may propagate in a direction not parallel to the Y-axis. Beams 12a and 12b may be dual or conjugate beams (e.g., including anti-phase reflection beams), and may be parallel or collimated. Thus, aperture 18 (and the first set of facets 14) can be configured to receive co-propagating dual beams separated by an offset distance 22.

[0025] When the first set of facets 14 is inclined with respect to the outer surface of the waveguide (e.g., not perpendicular to the parallel principal surface), and beams 12a and 12b are double beams, each facet of the first set of facets 14 will reflect one of the double beams (allowing the other to pass through). The reflected beams (e.g., beams 16a and 16b) become double beams due to the spacing of the first set of facets 14, as will be discussed further below.

[0026] Waveguide 10 is configured such that the offset distance 22 matches the projected distance along the main surfaces as beams 16a and 16b travel between parallel main surfaces. Beams 16a and 16b may propagate parallel to the X-axis via TIR toward and partially through the second set of facets 6 (not shown). In some implementations, beams 16a and 16b may propagate in directions not parallel to the X-axis. Since beams 16a and 16b form a double beam, waveguide 10 can be fully illuminated.

[0027] Figure 4 illustrates three examples of apertures 18 that may be used within the waveguide 10 (e.g., Examples 400, 402, and 404). For reference, cross-sectional views of beams 16a and 16b are shown. The offset distance 22 between the centerlines of sub-apertures 18a and 18b corresponds to the projection distance (e.g., semi-reflection cycle) along the main surface that one of the beams 16a or 16b creates between the parallel main surfaces. In other words, the offset distance 22 corresponds to a single "bounce" distance along the X-axis (if beams 16a and 16b propagate parallel to the X-axis).

[0028] In each of Examples 400 to 404, the offset distance 22 is the same. In Example 400, the sub-apers 18a1 and 18b1 have a relatively thin width and a wide absorbent material 20a. Such a mounting configuration may allow the projector 126 to be small in width (e.g., along the X-axis). In Example 402, the sub-apers 18a2 and 18b2 have a relatively wide width with a thinner absorbent material 20b. In Example 404, the sub-apers 18a3 and 18b3 have the maximum width available for a given offset distance 22. In other words, the sub-apers 18a3 and 18b3 are adjacent to each other with no absorbent material between them. Together, the sub-apers 18a3 and 18b3 may emulate a single aperture. Such a mounting configuration may allow for higher projection power, but the projector 126 may be larger in width (e.g., along the X-axis). The maximum opening width is generally twice the offset distance 22 (e.g., Example 404).

[0029] Figure 5 illustrates exemplary partial reflection of a beam by a first set 14 of facets in waveguide 10. As described above, beams 12a and 12b are received by the first set 14 of facets via TIR from aperture 18 (not shown). Beams 12a and 12b are separated by an offset distance 22. The first set 14 of facets partially reflects beams 12a and 12b to produce beams 16a1 and 16b1 and beams 16a2 and 16b2. The spacing between the first sets 14 of facets is such that beams 16a1 and 16b1 overlap in the XY plane (e.g., they generate a double beam toward a second set 6 of facets), and beams 16a2 and 16b2 overlap in the XY plane (e.g., they generate another double beam toward a second set 6 of facets). That is, the beam originating from one aperture has a conjugate “partner” with the beam originating from the other aperture, producing a uniform image. Without that one-to-one correspondence, there's a possibility of a lack of uniqueness (the images might not be uniform).

[0030] Adjacent double or overlapping beams (e.g., 16a1, 16b1, and 16a2, 16b2) are separated by a separation distance of 23. In other words, two adjacent facets of the first set 14 of facets produce beams 16a1 and 16b1, and the next two adjacent facets produce beams 16a2 and 16b2. The separation distance 23 may be the same as or different from the offset distance 22, depending on the various angles of the waveguide 10 and the spacing of the first set 14 of facets.

[0031] Figure 6 illustrates the exemplary partial reflection of Figure 5 when the aperture 18 includes two adjacent sub-apertures (e.g., similar to Example 404). The beam is still offset by an offset distance 22, but is shown with the corresponding illumination band 600. Because the sub-apertures are adjacent (e.g., there is no absorptive material 20 between them) and due to the spacing of the first set of facets 14, the reflection from the first set of facets 14 is fully illuminated (exemplified by the adjacent illumination band 600).

[0032] The spacing of the first set 14 of facets may be set such that the separation distance 23 is equal to the offset distance 22. If the spacing is too large, there may be gaps between the illumination bands 600. Conversely, if the spacing is too small, there may be overlaps in the illumination bands 600. In either case, the illumination may not be uniform.

[0033] The width of beam 34a may correspond to the width of the aperture 18. The width of beam 36a may be the same as the width of beam 34a for uniform illumination. Alternatively, the width may vary without departing from the scope of this disclosure.

[0034] In the illustrated example, the waveguide 10 can be fully illuminated, while the aperture 18 may be excessively wide (for example, the width of beam 34a may require an excessively large projector). Therefore, there may be a trade-off between illumination and the size of the aperture 18 and / or projector 126.

[0035] Figure 7 illustrates the exemplary partial reflection of Figure 5 when the aperture 18 includes a separated sub-aperture (similar to, for example, Examples 400 and 402). The offset distance 22 between beams 12a and 12b is the same as in Figure 6, but the width of beam 34b may be smaller than the width of beam 34a due to the thinner sub-aperture width. Because the sub-aperture is separated (e.g., non-adjacent), the width of beam 34b is not fully illuminated. Because the width of beam 34b is not fully illuminated, the reflection from it may not be fully illuminated (exemplified by area 30b between illumination bands 600). The width of beam 36c may be the same as the width of beam 34b for uniform illumination. On the other hand, the width may vary without departing from the scope of this disclosure.

[0036] To fully illuminate the waveguide 10, a third set of facets 700 may be added. The third set of facets 700 may be parallel to the first set of facets 14 and may be arranged alternately with the first set of facets 14. In other words, each facet of the first set of facets 14 may be equidistant from each facet of the third set of facets 700. As illustrated, the third set of facets 700 illuminates area 30b. The third set of facets 700 may enable full illumination when the aperture 18 contains absorbent material. Note that the aperture 18 in such an implementation is thinner than the aperture 18 in the example shown in Figure 7 (e.g., 34b is thinner / smaller than 34a, assuming the same offset distance 22). Design constraints may specify the total width of the aperture 18, and therefore the width of the absorbent material 20, which affects the sub-aperture width (assuming the offset distance 22 is fixed). Therefore, the smaller opening 18 can benefit from the third set of facets 700.

[0037] In this case as well, there may be a trade-off between complete illumination and the size of the opening 18 and / or the projector 126. Therefore, the absorber material 20 can have any width, including zero (e.g., adjacent sub-openings).

[0038] Figure 8 illustrates an example of a waveguide 10 having a virtual sub-aperture. The effect of the illustrated example is the same as that of Figure 3. That is, the first set of facets 14 receives beams 12a and 12b that are parallel and separated by an offset distance 22. For this purpose, the incident beam 800 is split into beams 12a and 12b. The splitting can be performed within waveguide 10 or in a separate waveguide attached to waveguide 10.

[0039] The incident beam 800 enters waveguide 10 or another waveguide through aperture 18. In the illustrated example, aperture 18 is not divided (e.g., aperture 18 functions as a single aperture). The incident beam 800 may have an incident angle less than the critical angle of waveguide 10 or the other waveguide and may be a double beam or a conjugate beam (as shown). The incident beam 800 may also be a single beam without departing from the scope of the present disclosure. The incident beam 800 may propagate parallel to the Y axis via TIR toward beam splitter 802 and may propagate partially (via partial reflectivity) through beam splitter 802. In some implementations, the incident beam 800 may propagate in a direction not parallel to the Y axis.

[0040] The beam splitter 802 allows a portion of the incident beam 800 to pass through as beam 12a and reflects the remaining portion of the incident beam 800 as beam 804 toward the reflector 806 (for example, along the X-axis). In some implementations, beam 804 may propagate in a direction not parallel to the X-axis. The reflector 806 reflects beam 804 as beam 12b.

[0041] A first virtual aperture 808 is located between the beam splitter 802 and the first set of facets 14. A second virtual aperture 810 is located between the reflector 806 and the first set of facets 14. The first virtual aperture 808 and the second virtual aperture 810 may be separated, similar to the sub-apertures 18a and 18b. The beam splitter 802 and the reflector 806 may be configured so that the first virtual aperture 808 and the second virtual aperture 810 are adjacent to each other.

[0042] The first virtual aperture 808 and the second virtual aperture 810 may be more abstract or more specific. For example, when the beam splitter 802 and reflector 806 are in another waveguide, the first virtual aperture 808 and the second virtual aperture 810 may be on the transition between the other waveguide and waveguide 10. However, when the beam splitter 802 and reflector 806 are in waveguide 10, there is no transition between the beam splitter 802 and reflector 806 and the first set 14 of facets, so the first virtual aperture 808 and the second virtual aperture 810 may be conceptual.

[0043] Figure 9 illustrates an example of waveguide 10 configured such that beams 12a and 12b are non-conjugate (single) parallel beams. The aperture 18 may be configured similarly to the examples in Figures 3 and 4, but with 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 may be of full height (e.g., extending between parallel main surfaces). In any case, the projector 126 that generates the non-conjugate beam may be smaller than the projector 126 that generates the conjugate beam. Also, because the beam is a single beam, each of the first set 14 of facets can reflect only one of beams 12a and 12b.

[0044] Unlike the example above, the first set of facets 14 may be perpendicular to the parallel main surface. Combined with the spacing of the sub-apers 18a and 18b, and the spacing of the first set of facets 14 that generate beams 16a and 16b with opposite TIR phases, the first set of perpendicular facets 14 can fully illuminate the waveguide 10 when beams 12a and 12b are single beams.

[0045] Furthermore, it should be noted that the structure in Figure 8 may also be applicable to the illustrated example. For example, beam splitters and reflectors may be used to generate virtual apertures instead of the shown split apertures.

[0046] The terms used herein are intended solely to describe 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 forms as well, unless the context otherwise explicitly indicates. The terms "includes," "comprises," and / or "comprising," when used herein, specify the presence of the described features, components, steps, actions, elements, and / or constituents, but do not exclude the presence or addition of one or more other features, components, steps, actions, elements, constituents, and / or groups thereof. Furthermore, terms such as up, upper, down, lower, above, below, left, right, front, and back are intended to be understood in the context of the expressions described and illustrated above, so that a wearable device may have such orientations in relation to a frame or various elements when supported by a frame or when illustrated in the drawings.

[0047] If any, all means or steps in the following claims, plus corresponding structures, materials, actions, and equivalents of functional elements, are intended to encompass any structures, materials, or actions to achieve a function in combination with other claimed elements when specifically claimed. 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. Various embodiments have been selected and described to best illustrate the principles and practical applications of the invention, and to enable those skilled in the art to understand the invention in terms of various embodiments with various modifications to suit specific anticipated uses. [Examples]

[0048] Example 1: Waveguide comprising: an opening having a pair of main surfaces parallel to each other and a pair of sub-openings aligned along a first axis, aligned along a second axis and offset along a third axis, the sub-openings configured to receive beams, and a first set of facets and a second set of facets, the first set of facets being formed between the main surfaces and including facets parallel to each other, and configured to receive beams from the opening and at least partially reflect beams toward the second set of facets, the second set of facets being formed between the main surfaces and including facets parallel to each other, and configured to at least partially reflect beams reflected by the first set of facets out of the waveguide, the sub-openings being offset by an offset distance corresponding to a projection distance along the main surfaces, during which the beam can travel while traversing one trip between the main surfaces after being reflected by the first set of facets.

[0049] Example 2: The waveguide according to Example 1, wherein the facets of the first set of facets and the second set of facets are inclined with respect to the outer surface of the waveguide.

[0050] Example 3: The waveguide according to Example 1, wherein the facets of the first set of facets are perpendicular to the main surface.

[0051] Example 4: A waveguide according to any one of the prior embodiments, wherein a beam propagates along a first axis to and through a first set of facets.

[0052] Example 5: A waveguide according to any one of the prior embodiments, wherein a beam propagates along, to, and through the second set of facets.

[0053] Example 6: A waveguide according to any one of the prior embodiments, wherein the distance between two facets of a first set of facets is configured such that a first beam from a first sub-aperture of the sub-aperture, at least partially reflected by a first facet of the two facets, overlaps with a second beam from a second sub-aperture of the sub-aperture, at least partially reflected by a second facet of the two facets.

[0054] Example 7: The waveguide according to Example 6, wherein overlapping beams partially reflected by two facets and overlapping beams of another pair partially reflected by the next adjacent pair of facets of the first set of facets are separated by a separation distance.

[0055] Example 8: The waveguide according to Example 7, wherein the separation distance is equal to the offset distance.

[0056] Example 9: The waveguide described in Example 7, wherein the separation distance is different from the offset distance.

[0057] Example 10: A waveguide according to any one of the prior embodiments, wherein the sub-apertures are adjacent to each other.

[0058] Example 11: A waveguide according to any one of the prior embodiments, wherein the sub-openings are arranged along a third axis and have gaps between them.

[0059] Example 12: The waveguide according to Example 11, further comprising an absorber disposed in the gap.

[0060] Example 13: The waveguide according to Example 11 or 12, wherein the distance between two facets of a first set of facets is configured such that a first beam from a first sub-aperture of the sub-aperture, at least partially reflected by a first facet of the two facets, overlaps with a second beam from a second sub-aperture of the sub-aperture, at least partially reflected by a second facet of the two facets, and the waveguide further comprises a third set of facets parallel to the first set of facets and arranged alternately between the first set of facets.

[0061] Example 14: Apparatus comprising a projector configured to generate a pair of parallel beams, a waveguide comprising an opening having a pair of main surfaces parallel to each other and a pair of sub-openings aligned along a first axis, aligned along a second axis and offset along a third axis, the sub-openings configured to receive each beam of the pair of parallel beams, and a first set of facets and a second set of facets, the first set of facets formed between the main surfaces and including facets parallel to each other and configured to receive beams from the opening and reflect the beams at least partially toward the second set of facets, the second set of facets formed between the main surfaces and including facets parallel to each other and configured to receive beams from the first set of facets and reflect the beams at least partially toward the waveguide, the sub-openings being offset by an offset distance corresponding to the projection distance along the main surfaces, during which the beams can travel while traversing one trip between the main surfaces after being reflected by the first set of facets.

[0062] Example 15: The apparatus according to Example 14, wherein the pair of parallel beams includes a pair of parallel conjugate beams.

[0063] Example 16: The apparatus according to Example 15, wherein the facets of the first set of facets are inclined with respect to the outer surface of the waveguide.

[0064] Example 17: The apparatus according to Example 14, wherein a pair of parallel beams includes a pair of non-conjugate beams.

[0065] Example 18: The apparatus according to Example 17, wherein the facets of the first set of facets are perpendicular to the main surface.

[0066] Example 19: The apparatus according to Example 17 or 18, wherein the opening has a height along a second axis that is less than the distance between the main surfaces.

[0067] Example 20: Waveguide comprising a pair of main surfaces parallel to each other, an opening configured to receive a beam, a beam splitter configured to receive a beam from the opening and pass a portion of the beam as a first beam toward a first set of facets and reflect another portion of the beam toward a reflector, a reflector configured to receive the other portion of the beam from the beam splitter and reflect the other portion of the beam as a second beam toward a first set of facets, and a first set of facets and a second set of facets, wherein the first set of facets is formed between the main surfaces and includes facets that are parallel to each other, and receives the first beam from the beam splitter and the second beam from the reflector, and passes the first beam toward the second set of facets as the reflected first beam, and Waveguide configured to at least partially reflect a second beam as a reflected second beam toward a second set of facets, the second set of facets being formed between the main surfaces and including facets that are parallel to each other, receiving the reflected first beam and the reflected second beam from the first set of facets, and configured to at least partially reflect the reflected first beam and the reflected second beam out of the waveguide, wherein the beam splitter and reflector are configured to offset the second beam from the first beam by an offset distance corresponding to a projection distance along the main surfaces, such that the reflected first beam and the reflected second beam can travel while the reflected first beam and the reflected second beam traverse one trip between the main surfaces.

[0068] Example 21: The waveguide according to Example 20, wherein the facets of the first set of facets and the second set of facets are inclined with respect to the outer surface of the waveguide.

[0069] Example 22: The waveguide according to Example 20, wherein the facets of the first set of facets are perpendicular to the main surface.

[0070] Example 23: A waveguide according to any one of Examples 20 to 22, wherein a beam splitter and a reflector are arranged in a first waveguide, a first set of facets and a second set of facets are arranged in a second waveguide, and the first waveguide is attached to the second waveguide.

[0071] Example 24: A waveguide according to any one of Examples 20 to 23, wherein the first set of facets is configured such that a first beam reflected from a facet of the first set of facets and a second beam reflected from an adjacent facet of the first set of facets overlap to produce overlapping reflected beams.

[0072] Example 25: The waveguide described in Example 24, wherein overlapping reflected beams are separated by an offset distance.

[0073] Example 26: A waveguide according to any one of Examples 20 to 25, wherein the offset distance is equal to the width of the opening along the axis.

[0074] Example 27: Apparatus comprising a projector, a waveguide configured to generate a beam, the waveguide comprising a pair of main surfaces parallel to each other, an opening configured to receive a beam, a beam splitter configured to receive a beam from the opening and pass a portion of the beam as a first beam toward a first set of facets and reflect another portion of the beam toward a reflector, a reflector configured to receive the other portion of the beam from the beam splitter and reflect the other portion of the beam as a second beam toward a first set of facets, and a first set of facets and a second set of facets, wherein the first set of facets is formed between the main surfaces and includes facets parallel to each other, and receives a first beam from the beam splitter and a second beam from the reflector, and the first beam is reflected toward the second set of facets as the first beam Apparatus comprising a waveguide, the beam splitter and reflector configured to receive the first and second beams reflected from the first set of facets, and to reflect the second beam at least partially toward a second set of facets as a reflected second beam, the second set of facets being formed between the main surfaces and including facets that are parallel to each other, and configured to receive the first and second beams reflected from the first set of facets, and to reflect the first and second beams reflected out of the waveguide, the beam splitter and reflector configured to offset the second beam from the first beam by an offset distance corresponding to a projection distance along the main surfaces, such that the second beam is parallel to the first beam and the reflected first and second beams can move while the reflected first and second beams traverse one trip between the main surfaces.

[0075] Example 28: The apparatus according to Example 27, wherein the beam includes a conjugated beam.

[0076] Example 29: The apparatus according to Example 28, wherein the facets of the first set of facets are inclined with respect to the outer surface of the waveguide.

[0077] Example 30: The apparatus according to Example 27, wherein the beam includes a non-conjugated beam.

[0078] Example 31: The apparatus according to Example 30, wherein the facets of the first set of facets are perpendicular to the main surface.

[0079] Example 32: The apparatus according to Example 30 or 31, wherein the opening has a height along another axis that is less than the distance between the main surfaces.

Claims

1. Waveguide, A pair of main surfaces that are parallel to each other, An opening comprising a pair of sub-openings aligned along a first axis, aligned along a second axis, and offset along a third axis, wherein the sub-openings are configured to receive their respective beams, A first set of facets and a second set of facets are provided, The first set of facets is formed between the main surfaces and includes facets that are parallel to each other, and is configured to receive the beam from the opening and to reflect the beam at least partially toward the second set of facets. The second set of facets is formed between the main surfaces and includes facets that are parallel to each other, and is configured to at least partially reflect the beam reflected by the first set of facets out of the waveguide. A waveguide in which the sub-aperture is offset by an offset distance corresponding to the projection distance along the main surface, during which the beam may travel while traversing one trip between the main surfaces after being reflected by a first set of facets.

2. The waveguide according to claim 1, wherein the facets of the first set of facets and the second set of facets are inclined with respect to the outer surface of the waveguide.

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

4. The waveguide according to claim 1, wherein the beam propagates along the first axis to and through the first set of facets.

5. The waveguide according to claim 1, wherein the beam propagates to and through the second set of facets.

6. The waveguide according to claim 1, wherein the distance between two facets of the first set of facets is configured such that the first beam from the first sub-aperture of the sub-aperture, which is at least partially reflected by the first facet of the two facets, and the second beam from the second sub-aperture of the sub-aperture, which is at least partially reflected by the second facet of the two facets, overlap.

7. The waveguide according to claim 6, wherein the overlapping beam partially reflected by the two facets and the overlapping beam of another pair partially reflected by the next adjacent pair of facets of the first set of facets are separated 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. The waveguide according to claim 1, wherein the sub-apertures are adjacent to each other.

11. The waveguide according to claim 1, wherein the sub-openings are arranged along the third axis and have gaps between them.

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

13. The distance between two facets of the first set of facets is configured such that the first beam from the first sub-opening of the sub-opening, which is at least partially reflected by the first facet of the two facets of the first set of facets, and the second beam from the second sub-opening of the sub-opening, which is at least partially reflected by the second facet of the two facets of the first set of facets, overlap. The waveguide further comprises a third set of facets that are parallel to the first set of facets and arranged alternately between the first set of facets, The waveguide according to claim 11 or 12, wherein the distance between two facets of the third set of facets is configured such that the first beam from the first sub-aperture of the sub-aperture, which is at least partially reflected by the first facet of the two facets of the third set of facets, and the second beam from the second sub-aperture of the sub-aperture, which is at least partially reflected by the second facet of the two facets of the third set of facets, overlap.

14. It is a device, A projector configured to generate a pair of parallel beams, Waveguide, A pair of main surfaces that are parallel to each other, An opening comprising a pair of sub-openings aligned along a first axis, aligned along a second axis, and offset along a third axis, wherein the sub-openings are configured to receive each beam of the pair of parallel beams, A first set of facets and a second set of facets are provided, The first set of facets is formed between the main surfaces and includes facets that are parallel to each other, and is configured to receive the beam from the opening and to reflect the beam at least partially toward the second set of facets. The second set of facets is formed between the main surfaces and includes facets that are parallel to each other, and is configured to receive the beam from the first set of facets and to reflect the beam out of the waveguide, at least partially. The apparatus comprises a waveguide, the sub-aperture being offset by an offset distance corresponding to the projection distance along the main surfaces, during which the beam can travel while it traverses one trip between the main surfaces after being reflected by a first set of facets.

15. The apparatus according to claim 14, wherein the pair of parallel beams includes a pair of parallel conjugate beams.

16. The apparatus according to claim 15, wherein the facets of the first set of facets are inclined with respect to the outer surface of the waveguide.

17. The apparatus according to claim 14, wherein the pair of parallel beams includes a pair of non-conjugate beams.

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

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

20. Waveguide, A pair of main surfaces that are parallel to each other, An opening configured to receive a beam, A beam splitter is configured to receive the beam from the opening, pass a portion of the beam as a first beam toward a first set of facets, and reflect another portion of the beam toward a reflector, A reflector configured to receive the other portion of the beam from the beam splitter and reflect the other portion of the beam as a second beam toward the first set of facets, The system comprises a first set of facets and a second set of facets, The first set of facets is formed between the main surfaces and includes facets that are parallel to each other, and is configured to receive the first beam from the beam splitter and the second beam from the reflector, and to at least partially reflect the first beam toward the second set of facets as a reflected first beam, and the second beam toward the second set of facets as a reflected second beam. The second set of facets is formed between the main surfaces and includes facets that are parallel to each other, and is configured to receive the reflected first beam and the reflected second beam from the first set of facets, and to reflect the reflected first beam and the reflected second beam out of the waveguide, at least partially. Waveguide, wherein the beam splitter and the reflector are configured such that the second beam is parallel to the first beam and offset from the first beam by an offset distance corresponding to a projection distance along the main surface, during which the reflected first beam and the reflected second beam can move while the reflected first beam and the reflected second beam traverse one trip between the main surfaces.

21. The waveguide according to claim 20, wherein the facets of the first set of facets and the second set of facets are inclined with respect to the outer surface of the waveguide.

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

23. The beam splitter and the reflector are arranged within the first waveguide. The first set of facets and the second set of facets are arranged within the second waveguide. The waveguide according to claim 20, wherein the first waveguide is attached to the second waveguide.

24. The waveguide according to claim 20, wherein the first set of facets is configured such that a first beam reflected from a facet of the first set of facets and a second beam reflected from an adjacent facet of the first set of facets overlap to produce overlapping reflected beams.

25. The waveguide according to claim 24, wherein the overlapping reflected beams are separated by the offset distance.

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

27. It is a device, A projector configured to generate a beam, Waveguide, A pair of main surfaces that are parallel to each other, An opening configured to receive the aforementioned beam, A beam splitter is configured to receive the beam from the opening, pass a portion of the beam as a first beam toward a first set of facets, and reflect another portion of the beam toward a reflector, A reflector configured to receive the other portion of the beam from the beam splitter and reflect the other portion of the beam as a second beam toward the first set of facets, The system comprises a first set of facets and a second set of facets, The first set of facets is formed between the main surfaces and includes facets that are parallel to each other, and is configured to receive the first beam from the beam splitter and the second beam from the reflector, and to at least partially reflect the first beam toward the second set of facets as a reflected first beam, and the second beam toward the second set of facets as a reflected second beam. The second set of facets is formed between the main surfaces and includes facets that are parallel to each other, and is configured to receive the first beam and the second beam reflected from the first set of facets, and to reflect the first beam and the second beam reflected out of the waveguide, at least partially. The apparatus comprises a waveguide, wherein the beam splitter and the reflector are configured such that the second beam is parallel to the first beam and offset from the first beam by an offset distance corresponding to a projection distance along the main surface, during which the reflected first beam and the reflected second beam can move while the reflected first beam and the reflected second beam traverse one trip between the main surfaces.

28. The apparatus according to claim 27, wherein the beam includes a conjugate beam.

29. The apparatus according to claim 28, wherein the facets of the first set of facets are inclined with respect to the outer surface of the waveguide.

30. The apparatus according to claim 27, wherein the beam includes a non-conjugated beam.

31. The apparatus according to claim 30, wherein the facets of the first set of facets are perpendicular to the main surface.

32. The apparatus according to claim 30 or 31, wherein the opening has a height along another axis that is less than the distance between the main surfaces.

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