Waveguide edge with reduced reflectivity

Abstract

An augmented reality system may include a waveguide having an edge surface extending between opposing light guide surfaces. The waveguide may direct light toward the edge surface. The waveguide may include a reduced reflectivity film, such as an absorber film or a photovoltaic film, disposed on the edge surface. To form a reduced reflectivity film, a curable material may be disposed on the dissolvable film. The curable material may be cured when disposed on the dissolvable film such that the cured material forms a reduced reflectivity structure on the dissolvable film. The dissolvable film may be dissolved such that the reduced reflectance structure remains intact as a reduced reflectance film, which may be adhered to the edge surface, for example, with a primer layer. The edge surface may include a nanostructure sized to be less than the half wavelength of the guided light, which nanostructure may reduce the reflectivity of the edge surface.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 489,952, filed March 13, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to waveguides, for example, used in augmented reality displays. Background Technology

[0004] Augmented reality headsets can include at least one display capable of showing users additional content that can be overlaid on real-world objects in the user's vicinity. Efforts to improve augmented reality headsets are ongoing. Attached Figure Description

[0005] Figure 1 A side view showing some examples of augmented reality systems.

[0006] Figure 2 The image shows a side view of some examples of an augmented reality system, in which a film for reducing reflectivity is adhered to the edge surface of a waveguide.

[0007] Figure 3 The image shows a side view of some examples of an augmented reality system, where a film for reducing reflectivity has been adhered to the edge surface of a waveguide.

[0008] Figure 4 The side view shows some examples of an augmented reality system, in which a reflective film has been adhered to the edge surface of a waveguide and shaped to have a size that roughly corresponds to the area of ​​the edge surface.

[0009] Figure 5 A side view of some examples of an augmented reality system is shown, in which a photovoltaic film will be adhered to the edge surface of a waveguide.

[0010] Figure 6 A side view of some examples of an augmented reality system is shown, in which a photovoltaic film has been adhered to the edge surface of a waveguide.

[0011] Figure 7 The image shows a side view of some examples of an augmented reality system, in which a photovoltaic film has been adhered to the edge surface of a waveguide and shaped to have a size that roughly corresponds to the area of ​​the edge surface.

[0012] Figure 8The side view shows some examples of an augmented reality system, in which a photovoltaic film has been adhered to the edge surface of a waveguide, shaped to have a size roughly corresponding to the area of ​​the edge surface, and electrically connected to a battery.

[0013] Figure 9 The flowchart shows some examples of methods for reducing reflections in waveguides.

[0014] Figure 10 The image shows a side view of some examples of an augmented reality system, where the edge surface of the waveguide includes nanostructures configured to reduce the reflectivity of the edge surface.

[0015] Figure 11 This shows a section taken parallel to the edge surface at a first plane closer to the bottom of the nanostructure than the top of the nanostructure. Figure 10 A cross-sectional view of the nanostructure.

[0016] Figure 12 This shows a section taken parallel to the edge surface at a second plane midway between the bottom and top of the nanostructure. Figure 10 A cross-sectional view of the nanostructure.

[0017] Figure 13 This shows a section taken parallel to the edge surface at a third plane closer to the top of the nanostructure than the bottom of the nanostructure. Figure 10 A cross-sectional view of the nanostructure.

[0018] Figure 14 The image shows a side view of some examples of an augmented reality system, where the edge surface of the waveguide includes nanostructures configured to reduce the reflectivity of the edge surface.

[0019] Throughout the various views, corresponding reference numerals indicate the relevant parts. Elements in the accompanying drawings are not necessarily drawn to scale. The configurations shown in the drawings are merely examples and should not be construed as limiting in any way. Detailed Implementation

[0020] Augmented reality headsets can include two displays. Each display can be located near the user's respective eyes. The displays can be worn, for example, as glasses or a headset. Each display can be at least partially transparent, allowing the user to view real-world objects in their vicinity through each display. Each display can show the user additional content that appears to be overlaid on the real-world objects in the user's vicinity.

[0021] In some examples of augmented reality displays, a light source can guide light into a waveguide. The waveguide can extend over a surface area of ​​the display. The waveguide can guide light, as directed light, from the light source into all, most, or at least some of the surface area of ​​the waveguide. Diffraction elements distributed across the surface area of ​​the waveguide can extract at least some of the guided light from the waveguide and direct the extracted light toward the user's eyes. The light extracted from the waveguide by the diffraction elements provides additional content to the user. Because the diffraction elements can occupy a relatively small proportion of the waveguide's surface area, the remaining surface area of ​​the waveguide can be at least partially transparent, allowing the user to view surrounding real-world objects through the waveguide.

[0022] To help avoid brightness differences across the surface areas of a display—for example, a portion of the display relatively closer to the light source being brighter than another portion relatively farther away—diffraction elements can be varied in size and / or shape across the surface area of ​​the waveguide. For instance, diffraction elements relatively closer to the light source can be shaped and sized to have relatively low diffraction efficiency (e.g., a value between 0 and 1 representing the proportion of incident light coupled to a particular diffraction order), while diffraction elements relatively farther away from the light source can be shaped and sized to have relatively high diffraction efficiency.

[0023] If the diffraction element does not completely extract all the guided light from the waveguide, a portion of the guided light can be reflected from the edge surfaces of the waveguide to form false reflections within the waveguide. The diffraction element can then direct some of these false reflections toward the viewer's eye as a ghosting image, which reduces contrast or impairs the integrity of the image formed by the display.

[0024] The augmented reality systems and methods described below can help reduce reflections from the edge surfaces of waveguides. For example, waveguides may include films that reduce reflectivity, such as absorbing films or photovoltaic films, disposed on the edge surfaces. In some examples, photovoltaic films can convert reflected light into electrical energy, which can be stored by batteries and can help reduce the overall power consumption of the augmented reality system.

[0025] To form a dereflective film, a curable material can be deposited onto a soluble film. The curable material can be cured while deposited on the soluble film, forming a dereflective structure on the soluble film. The soluble film can be dissolved, allowing the dereflective structure to remain intact. As a dereflective film, the dereflective film can be adhered to an edge surface, for example, with a primer layer. In some examples, curing can introduce stress into the substrate (on which the curable material is cured), which can alter the shape of the substrate or create microcracks on its surface. For example, in a system where the curable material is deposited directly onto the edge surface of a waveguide and cured while on the edge surface, curing can introduce stress on the edge surface and alter the shape of the waveguide, leading to distortion of the displayed image. Using a soluble film as described herein allows stress to be introduced within the soluble film, rather than on the edge surface. When the soluble film is dissolved, the stress disappears, allowing the adhesion of the dereflective film to the edge surface to avoid introducing stress on the edge surface. This helps prevent alteration of the waveguide shape and can help reduce or prevent distortion of the displayed image.

[0026] According to some examples, the edge surface of a waveguide may include nanostructures sized to be less than half the wavelength of the guided light, which can reduce the reflectivity of the edge surface. The nanostructures can create an effective refractive index gradient at the edge surface of the waveguide, which can reduce reflections from the edge surface. Compared to edge surfaces lacking an effective refractive index gradient (e.g., a planar interface between the waveguide material and air), edge surfaces including nanostructures can reduce or eliminate reflections from the edge surface, which can improve the contrast of a display.

[0027] Figure 1 A side view of some examples of the augmented reality system 100 is shown. Figure 1 The augmented reality system 100 is just one example of an augmented reality system, which may include elements disposed on the edge surface of the waveguide to reduce reflection and lower the reflectivity of the edge surface. Other suitable augmented reality systems may also be used.

[0028] Augmented reality system 100 may include a waveguide 102. Waveguide 102 may be referred to as an optical guide. For the purposes of this document, the terms waveguide and optical guide are used interchangeably. Waveguide 102 may be configured as a planar optical guide having light-guiding surfaces 106 (e.g., light-guiding surface 106A and opposing light-guiding surfaces 106B). During operation of augmented reality system 100, waveguide 102 may guide guided light 114 via total internal reflection from light-guiding surfaces 106A and 106B. For example, the guided light 114 may undergo multiple reflections from opposing light-guiding surfaces 106. In some examples, waveguide 102 may be planar, such that light-guiding surfaces 106 are planar and parallel. In other examples, waveguide 102 may be bent to have a relatively large radius of curvature. For example, waveguide 102 may optionally be shaped as an eyeglass lens having opposing light-guiding surfaces 106, both of which are bent outwards from the user's eye to avoid contact with the user's eyelashes. Waveguide 102 may be formed of a material that is transparent or at least partially transparent to wavelengths in the visible portion of the electromagnetic spectrum (e.g., between approximately 400 nm and approximately 700 nm). Suitable materials for waveguide 102 include glass, fused silica, optical plastics such as polycarbonate, and others.

[0029] The augmented reality system 100 may include a plurality of diffraction elements 104 positioned on or within a region of the light-guiding surface 106 of the waveguide 102. Figure 1 In this configuration, the diffraction element 104 is positioned on or within a region of the light guide surface 106A. Alternatively, the diffraction element 104 may be positioned on or within a region of the light guide surface 106B. Figure 1 An augmented reality system 100 is shown, comprising three diffraction elements 104A, 104B, and 104C. In practice, an actual augmented reality system 100 may include significantly more than three diffraction elements, such as hundreds, thousands, or hundreds of thousands of diffraction elements 104.

[0030] Augmented reality system 100 may include a light source 112 disposed at a first edge 118 of the light-guiding surface 106 of waveguide 102. Suitable light sources may include light-emitting diodes, such as white light-emitting diodes or single-wavelength light-emitting diodes (e.g., red, green, and blue light-emitting diodes), laser diodes, or other suitable light sources. Light source 112 may guide light 110 into waveguide 102. Waveguide 102 may be configured to guide light 110 from the light source as guided light 114. Light source 112 may be referred to as a projector or light engine and may include a reflective, transmissive, or emissive display panel, such as a liquid crystal on silicon (LCoS) or a microLED display. Light source 112 may also include optics such as one or more lenses to focus an image from the display panel as a pupil onto an input grating of waveguide 102.

[0031] The diffraction element 104 can extract the guided light 114 from the waveguide 102 as extracted light 116. The diffraction element 104 can vary in at least one of its size and shape. As the guided light 114 propagates away from the light source 112, for example, as the distance away from the first edge 118 of the light-guiding surface 106 increases, the amount of guided light 114 within the waveguide 102 decreases. The “amount” of guided light 114 can correspond to the energy of the guided light in the waveguide 102, as the amount of energy decreases because the diffraction element 104 can extract the guided light 114 from the waveguide 102 as the guided light 114 propagates away from the light source 112. For example, near the light source 112, the first amount of guided light 114A can be relatively high. The first diffraction element 104A can extract some light 116 from the waveguide 102, such that the second amount of guided light 114B is less than the first amount of guided light 114A. The second diffraction element 104B can also extract some light 116 from the waveguide 102, such as the light extraction portion 116B, so that the third quantity of the guided light 114C is less than the second quantity of the guided light 114B. The third diffraction element 104C can also extract some light 116 from the waveguide 102, such as the light extraction portion 116C, and so on.

[0032] It should be noted that in practice, diffraction element 104 may not extract light from waveguide 102 alone to generate extracted light 116, but may cooperate with adjacent diffraction elements 104 to replicate the input pupil across a region of the waveguide 102 surface, thereby not only generating extracted light 116 but also ensuring that the projected image can be seen over the largest possible area of ​​viewing angle. For example, diffraction elements 104 may be spaced apart at a distance that allows guided light 114 to be directed into extracted light 116 with a specific propagation direction or a specific range of propagation directions. Diffraction elements 104 may have varying sizes and shapes across the surface region of the light-guiding surface 106 of waveguide 102. Depending on their position across the light-guiding surface 106 of waveguide 102, the size and shape of diffraction elements 104 can at least partially determine how much guided light 114 is extracted to form extracted light 116.

[0033] Augmented reality system 100 may include an edge surface 120 extending between opposing light-guiding surfaces 106A, 106B of waveguide 102. Waveguide 102 may guide guided light 114 between opposing light-guiding surfaces 106A, 106B toward edge surface 120. In some examples, edge surface 120 may be planar. In some examples, edge surface 120 may be orthogonal or substantially orthogonal to light-guiding surfaces 106A and 106B. In some examples, edge surface 120 may be at a non-orthogonal angle relative to light-guiding surfaces 106A and 106B. In some examples, edge surface 120 may be circular. In some examples, edge surface 120 may include one or more corners.

[0034] The augmented reality system 100 may include a reflection-reducing element 122 disposed on an edge surface 120 to reduce the reflectivity of the edge surface 120. The reflection-reducing element 122 may receive at least some of the guided light 114 that strikes the reflection-reducing element 122. In response to receiving the guided light 114, the reflection-reducing element 122 may generate reduced reflection 108, or may generate no reflection at all. Specifically, the reduced reflection 108 may include less optical power than the reflection from the planar interface between the waveguide 102 and air. By reducing or eliminating the amount of reflected light, the reflection-reducing element 122 may reduce stray light that may be included in the extracted light 116, and thus may increase the contrast of the image produced by the augmented reality system 100.

[0035] In some examples, the reflection-reducing element 122 may include a cured film. For example, the cured film may be an absorbing film comprising an absorbing material that can absorb guided light impacting the cured film. As another example, the cured film may be a photovoltaic film that can convert at least a portion of the guided light impacting the cured film into electrical energy. Figures 2 to 4 Examples of cured films and techniques for adhering cured films to the edge surfaces of waveguides are shown. Figures 5 to 8 Examples of cured films and techniques for adhering cured films to the edge surfaces of waveguides are shown, wherein the cured film is a photovoltaic film.

[0036] In some examples, the reflection-reducing element 122 may include a nanostructure. The nanostructure can create an effective refractive index gradient at the edge surface, which can reduce or eliminate reflections caused by interfaces where the refractive index changes abruptly or discontinuously (e.g., the planar interface between waveguide 102 and air). Figure 10 and Figure 11 Some examples of nanostructures are shown.

[0037] Figure 2 A side view of some examples of an augmented reality system 200 is shown, in which a reflective destigmatization film 202 is adhered to an edge surface 120 of a waveguide 102. The edge surface 120 may be located on opposite sides of the waveguide 102 on an axis passing through an input grating (receiving light from a projector) and an output grating (guiding light toward the user's eyes). The reflective destigmatization film 202 may be suitable for use as... Figure 1 At least a portion of the solidified film of the reflective element 122 of the augmented reality system 100.

[0038] To form the reflectivity-reducing film 202, a curable material can be applied to the soluble film, for example, by one or more of evaporation, sputtering, electron beam deposition, or another suitable coating technique. While the curable material is on the soluble film, it can be cured, such that the cured material forms a reflectivity-reducing structure on the soluble film. For example, the curable material can be cured by one or more of thermosetting, UV curing, moisture curing, oxygen curing, or another suitable curing technique. Curing the curable material can cause it to shrink. This shrinkage can generate stress in the soluble film. The soluble film can be dissolved, such that the reflectivity-reducing structure remains intact on the dissolved film to form the reflectivity-reducing film 202. When the soluble film is dissolved, the stress disappears, such that the reflectivity-reducing structure does not include a significant amount of internal stress. The relatively stress-free reflectivity-reducing film 202 can then be adhered to the edge surface 120 of the waveguide 102 without applying a significant amount of stress to the edge surface 120. Compared to forming a structure that reduces reflectivity directly on the edge surface 120 of waveguide 102 (which may apply stress to the edge surface 120, potentially deforming its shape), using the described soluble film can help avoid applying stress to the edge surface 120, and thus help avoid deforming the shape of the edge surface 120 and / or the light guide surfaces 106A, 106B.

[0039] In some examples, the curable material may include an absorbing material, such as black ink, or another suitable material that can absorb at least some of the light impacting the absorbing material. In some examples, the structure for reducing reflectivity may include an absorbing structure. In some examples, the film 202 for reducing reflectivity may include an absorbing film.

[0040] In some examples, the curable material may include a photovoltaic material. In some examples, the structure for reducing reflectivity may include a photovoltaic structure. In some examples, the film 202 for reducing reflectivity may include a photovoltaic film. The following... Figures 5 to 8 A detailed example of a photovoltaic film adhered to the edge surface of a waveguide is shown.

[0041] return Figure 2 A primer layer 204 can be applied to the edge surface 120 of the waveguide 102. In some examples, the primer layer 204 may include an adhesive material that can adhere the reflectivity-reducing film to the edge surface 120. The primer layer 204 may not require curing and therefore may not shrink or exert stress on the edge surface 120.

[0042] Figure 3 A side view of some examples of an augmented reality system 300 is shown, in which a reflective destigmatization film 202 has been adhered to the edge surface 120 of a waveguide 102. The reflective destigmatization film 202 may be suitable for use as... Figure 1 At least a portion of the solidified film of the anti-reflection element 122 of the augmented reality system 100.

[0043] In some examples, at least a portion of the dereflective film 202 has been positioned on the primer layer 204, such that the primer layer 204 adheres the dereflective film 202 to the edge surface 120. In some examples, the dereflective film 202 has been forced against the edge surface 120 of the waveguide 102. In some examples, the primer layer 204 has adhered or attached the dereflective film 202 to the edge surface 120 of the waveguide 102. This attachment may not require curing, so that the dereflective film 202 does not shrink during adhesion to the edge surface 120 and therefore does not exert any stress on the edge surface 120.

[0044] Figure 4A side view of some examples of an augmented reality system 400 is shown, in which a dereflective film 202 has been adhered to the edge surface 120 of the waveguide 102 and trimmed to have a size that approximately corresponds to the area of ​​the edge surface 120. For example, this size could be 100%, 90%, 80%, 70%, or another suitable proportion of the area of ​​the edge surface 120. In some examples, the dereflective film 202 may be trimmed to cover the central region of the edge surface 120 of the waveguide 102, such that the boundary regions remain uncovered. Including the uncovered boundary regions helps ensure that the dereflective film 202 is not snagged or torn during the assembly of the augmented reality system.

[0045] The antireflectivity membrane 202 can receive at least some of the guided light 114 that strikes the antireflectivity membrane 202. In response to receiving the guided light 114, the antireflectivity membrane 202 can produce reduced reflection 108, or it can produce no reflection at all. Specifically, reduced reflection 108 can include less optical power than reflection from the planar interface between the waveguide 102 and air. By reducing or eliminating the amount of reflected light, the antireflectivity membrane 202 can reduce the amount of stray light that may be included in the light extracted from the waveguide 102, and thus can increase the performance of the augmented reality system 100. Figure 1 The contrast of the generated image.

[0046] Figure 5 A side view of some examples of an augmented reality system 500 is shown, in which a photovoltaic film 502 will be adhered to the edge surface 120 of a waveguide 102. The photovoltaic film 502 may be suitable for use as... Figure 1 The augmented reality system 100 has at least a portion of a solidified film of a reflective element 122 (and specific examples of films that reduce reflectivity).

[0047] The photovoltaic film 502 may include a photovoltaic layered structure, which may also convert at least a portion of the guided light impacting the photovoltaic layered structure into electrical energy.

[0048] The photovoltaic layered structure may include a first electrode 512 to be disposed on the edge surface 120 of the waveguide 102. The first electrode 512 may be formed of a material that is at least substantially transparent at the wavelength of the guided light, such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), or one or more other suitable materials, optionally having one or more dopants.

[0049] The photovoltaic layered structure may include a first photovoltaic material layer 514 disposed on a first electrode 512 and a second photovoltaic material layer 516 disposed on the first photovoltaic material layer 514. In some examples, the interface between the first photovoltaic material layer 514 and the second photovoltaic material layer 516 may form a pn junction. In some examples, the first photovoltaic material layer 514 and the second photovoltaic material layer 516 may convert at least a portion of the guided light impacting the first photovoltaic material layer 514 and the second photovoltaic material layer 516 (e.g., a pn junction) into electrical energy.

[0050] The first photovoltaic material layer 514 and the second photovoltaic material layer 516 can be formed of a semiconductor material capable of absorbing the guided light 114. For absorption, the electronic band gap of the semiconductor material can be smaller than the minimum photon energy of the guided light 114. Suitable semiconductor materials for the first photovoltaic material layer 514 and the second photovoltaic material layer 516 may include perovskite, octylammonium iodide, spiro-OMeTAD (2,2′,7,7′-tetratetra(N,N-di-p-methoxyphenylamino)-9,9′-spirodifluorene), copper indium gallium selenide (CIGS), cadmium sulfide (CdS), cadmium telluride (CdTe), and others. The first photovoltaic material layer 514 and the second photovoltaic material layer 516 may comprise different materials or the same material with different dopants and / or different concentrations of the same dopant.

[0051] In other examples, an intrinsic layer may optionally be included between the first photovoltaic material layer 514 and the second photovoltaic material layer 516, such that the first photovoltaic material layer 514, the intrinsic layer, and the second photovoltaic material layer 516 form a pin junction. Other suitable junction structures may also be used to convert incident light into electrical energy.

[0052] The photovoltaic layered structure may include a second electrode 518 disposed on a second photovoltaic material layer 516. In some examples, the second electrode 518 may be formed of the same material as the first electrode 512. In other examples, because the second electrode 518 may optionally be opaque or at least partially opaque at the wavelength of the guided light, the second electrode 518 may be formed of, for example, silver, aluminum, gold, copper, or other conductive metals.

[0053] Figure 6 A side view of some examples of an augmented reality system 600 is shown, in which a photovoltaic film 502 has been adhered to the edge surface 120 of a waveguide 102. The photovoltaic film 502 may be suitable for use as... Figure 1 The augmented reality system 100 has at least a portion of a solidified film of a reflective element 122 (and specific examples of films that reduce reflectivity).

[0054] In some examples, at least a portion of the photovoltaic film 502 has been positioned onto a primer layer (not shown), such that the primer layer adheres the photovoltaic film 502 to the edge surface 120. In some examples, the photovoltaic film 502 has been forced against the edge surface 120 of the waveguide 102. In some examples, the primer layer has adhered or attached the photovoltaic film 502 to the edge surface 120 of the waveguide 102. This adhesion may not require curing, so that the photovoltaic film 502 may not shrink during adhesion to the edge surface 120 and therefore will not exert any stress on the edge surface 120.

[0055] Figure 7 A side view of some examples of an augmented reality system 700 is shown, in which a photovoltaic film 502 has been adhered to the edge surface 120 of the waveguide 102 and has been shaped to have a size that roughly corresponds to the area of ​​the edge surface 120.

[0056] The photovoltaic film 502 can receive at least some of the guided light 114 that impacts the photovoltaic film 502. In response to receiving the guided light 114, the photovoltaic film 502 can produce reduced reflection 108, or it can produce no reflection at all. Specifically, reduced reflection 108 can include less optical power than that reflected from the planar interface between the waveguide 102 and the air. By reducing or eliminating the amount of reflected light, the photovoltaic film 502 can reduce the amount of stray light that may be included in the light extracted from the waveguide 102, and thus can increase the power output of the augmented reality system 100. Figure 1 The contrast of the generated image.

[0057] Figure 8 A side view of some examples of an augmented reality system 800 is shown, in which a photovoltaic film 502 has been adhered to the edge surface 120 of a waveguide 102, shaped to have dimensions approximately corresponding to the area of ​​the edge surface 120, and electrically connected to a battery 802. The battery 802 may be electrically connected to the photovoltaic film 502 and may store electrical energy generated by the photovoltaic film 502.

[0058] In some examples, battery 802 may be electrically connected to first photovoltaic material layer 514 and second photovoltaic material layer 516 via first electrode 512 and second electrode 518, respectively. For example, battery 802 may have a first terminal electrically connected to first electrode 512 via first contact line 804, and a second terminal electrically connected to second electrode 518 via second contact line 806. In some examples, the first contact line 804 and second contact line 806 may be printed on a suitable substrate using silver, gold, aluminum, copper, or another metal or other suitable conductive material.

[0059] In some examples, battery 802 may be a system battery (or may be electrically coupled to a system battery), which may be a light source 112 in the augmented reality system. Figure 1 Powered by waveguide 102 and other suitable circuitry. In this way, the augmented reality system can convert light from waveguide 102, which would otherwise be wasted, into electrical energy, and thus reduce the overall energy consumption of the augmented reality system.

[0060] Figure 9 Flowcharts are shown illustrating some examples of a method 900 for reducing reflections in a waveguide (e.g., waveguide 102). Method 900 is just one example of a method for reducing reflections in a waveguide; other methods may also be used.

[0061] At operation 902, a curable material can be applied to a soluble film.

[0062] At operation 904, when the curable material is on the soluble film, the curable material can be cured, causing the cured material to form a structure with reduced reflectivity on the soluble film. In some examples, curing may include one of thermal curing, UV curing, moisture curing, or oxygen curing. Other curing techniques may also be used. In some examples, curing may introduce shrinkage of the curable material. The shrinkage of the curable material can introduce stress in the soluble film without introducing stress on the edge surface of the waveguide.

[0063] At operation 906, the soluble film can be dissolved, so that the structure that reduces reflectivity remains intact on the dissolved film, thereby forming a film that reduces reflectivity.

[0064] At operation 906, a primer layer can be applied to the edge surface of the waveguide. The edge surface can extend between the light-guiding surfaces of the waveguide.

[0065] At operation 910, at least a portion of the reflectivity-reducing film can be positioned on the primer layer, such that the primer layer adheres the reflectivity-reducing film to the edge surface.

[0066] In some examples, method 900 may also optionally include trimming the reflectivity-reducing film to have a size that roughly corresponds to the area of ​​the edge surface.

[0067] In some examples, the curable material may include an absorbing material. The structure that reduces reflectivity may include an absorbing structure. The film that reduces reflectivity may include an absorbing film. The absorbing film may include black ink or another suitable absorbing material.

[0068] In some examples, curable materials may include photovoltaic materials. Structures that reduce reflectivity may include photovoltaic structures. Films that reduce reflectivity may include photovoltaic films.

[0069] In some examples, the photovoltaic film may include a first electrode disposed on an edge surface and be at least substantially transparent at the wavelength of the light guided by the waveguide. A first photovoltaic material layer may be disposed on the first electrode. A second photovoltaic material layer may be disposed on the first photovoltaic material layer. The first and second photovoltaic material layers may be configured to convert at least a portion of the guided light striking the first and second photovoltaic material layers into electrical energy. A second electrode may be disposed on the second photovoltaic material layer.

[0070] In some examples, method 900 may optionally include storing electrical energy in a battery electrically connected to a first photovoltaic material layer and a second photovoltaic material layer via a first electrode and a second electrode.

[0071] Figure 10 A side view of some examples of an augmented reality system 1000 is shown, wherein the edge surface 120 of the waveguide 102 includes a nanostructure 1002 configured to reduce the reflectivity of the edge surface 120. The nanostructure 1002 can be suitable for use as... Figure 1 At least a portion of the reflection-reducing element 122 of the augmented reality system 100.

[0072] In some examples, the nanostructure 1002 may be sized to be less than half the wavelength of the light guided by the waveguide 102. For example, for light in the visible portion of the electromagnetic spectrum (with wavelengths between approximately 400 nm and approximately 700 nm), the nanostructure 1002 may be sized to be less than approximately 400 nm or less than approximately 200 nm. In some examples, each nanostructure 1002 may have a lateral dimension along a plane parallel to the edge surface 120 that is less than 400 nm or less than 200 nm, or less than the wavelength or half the wavelength of the light guided by the waveguide 102.

[0073] In some examples, the nanostructure 1002 can be sized to modulate the refractive index at the edge surface. For example, each location along the longitudinal axis perpendicular to the edge surface 120 can have an effective refractive index. The effective refractive index can vary smoothly (e.g., without discontinuities) over a range between the refractive index of the waveguide 102 material and the refractive index of air (e.g., 1). Because the effective refractive index can vary smoothly along the longitudinal axis, reduced reflection can occur (compared to reflection at the planar interface between the waveguide 102 and air).

[0074] In some examples, nanostructure 1002 may have a bottom portion facing the interior of waveguide 102 and a top portion facing away from the interior of waveguide 102. For example, the top portion may include a location, structure, or height, or the nanostructure may be located on a surface furthest from the interior of waveguide 102. In some examples, the bottom portion may include a bottom 1004 of the nanostructure that can be disposed in a plane (B). In some examples, the top portion may include a top 1006 of the nanostructure that can be disposed in a plane (T). As used herein, the terms “bottom” and “top” are intended to refer to a specific location on nanostructure 1002 and are not intended to correspond to an absolute location relative to the gravitational field of the Earth or any other frame of reference.

[0075] The nanostructure 1002 may have a material fill factor truncated in a cross-sectional plane parallel to the edge surface 120. The material fill factor may correspond to the proportion of the unit cross-sectional area occupied by the nanostructure 1002. The material fill factor can decrease from the bottom 1004 of the nanostructure to the top 1006 of the nanostructure. For example, Figures 11 to 13 The corresponding cross section of the nanostructure 1002 is shown in the corresponding cross section plane parallel to the edge surface 120.

[0076] Figure 11 This shows a section taken parallel to the edge surface 120 at a first plane closer to the bottom 1004 of the nanostructure than the top 1006 of the nanostructure. Figure 10 A cross-sectional view of the 1002 nanostructure. Figure 11 In the first plane shown, the nanostructure 1002 occupies 76.6% of the cross-sectional area, resulting in a material fill factor of 76.6%.

[0077] Figure 12 This shows a section taken parallel to the edge surface 120 at a second plane between the bottom 1004 and the top 1006 of the nanostructure. Figure 10 A cross-sectional view of the 1002 nanostructure. Figure 12 In the second plane shown, the nanostructure 1002 occupies 39.1% of the cross-sectional area, resulting in a material fill factor of 39.1%.

[0078] Figure 13 This shows a section taken parallel to the edge surface 120 at a third plane closer to the top 1006 of the nanostructure than the bottom 1004 of the nanostructure. Figure 10 A cross-sectional view of the 1002 nanostructure. Figure 12 In the second plane shown, the nanostructure 1002 occupies 14.1% of the cross-sectional area, resulting in a material fill factor of 14.1%.

[0079] Figures 11 to 13The numerical examples provided are merely illustrative. In practice, any suitable numerical value may be used. In some examples, the material fill factor may optionally monotonically decrease from a maximum value (e.g., 100% or less) to a minimum value (e.g., 0% or greater than 0%) from the top 1006 of the nanostructure to the bottom 1004 of the nanostructure. The cross-sectional shape of the nanostructure 1002, truncated parallel to the edge surface 120, may be square, rectangular, circular, elliptical, elongated, or any other suitable cross-sectional shape. The nanostructure 1002 may be amorphous or may have other shapes, such as conical.

[0080] Nanostructure 1002 may define the effective refractive index of each cross-sectional plane (e.g., each cross-sectional plane between plane (B) and plane (T)) from the bottom 1004 to the top 1006 of the nanostructure. The effective refractive index may vary depending on the material fill factor at the cross-sectional plane. For example, the effective refractive index may be equal to the sum of quantities A and B, where quantity A is the product of the refractive index of the waveguide material and the material fill factor, and quantity B is the product of the refractive index of air (e.g., 1) and quantity C, where quantity C equals 100% minus the material fill factor. In some examples, such as in a configuration where the material fill factor at the bottom 1004 of the nanostructure may be 100% or nearly 100%, the effective refractive index at the bottom 1004 of the nanostructure may match or substantially match the refractive index of the waveguide material of waveguide 102.

[0081] In some examples, the nanostructure 1002 may be formed into a pyramid, cone, moth-eye structure, amorphous structure, repeating structure, non-repeating structure, or other suitable shape. In some examples, all of the nanostructures 1002 may be formed into the same shape. In other examples, at least some of the nanostructures 1002 may have different shapes.

[0082] In a specific example, the nanostructure 1002 can be formed into a pyramid. Each pyramid can have a base facing the interior of the waveguide 102 and a top facing away from the interior of the waveguide 102. Each pyramid can have a cross-sectional area taken in a cross-sectional plane parallel to the edge surface 120. The cross-sectional area can monotonically decrease from the base to the top of the pyramid. Each pyramid can define an effective refractive index for each cross-sectional plane from the base to the top. The effective refractive index can vary depending on the cross-sectional area of ​​the pyramid at the cross-sectional plane. The effective refractive index at the base of the pyramid can match the refractive index of the waveguide material of the waveguide 102.

[0083] In some examples, for example Figure 10In this configuration, the apex of the pyramid may include a generally flat area that is parallel to the plane of the edge surface 120. For these examples, the effective refractive index at the apex of the pyramid may be slightly different from the refractive index of air.

[0084] Figure 14 A side view of some examples of an augmented reality system 1400 is shown, wherein the edge surface 120 of the waveguide 102 includes a nanostructure 1402 configured to reduce the reflectivity of the edge surface 120. The nanostructure 1402 can be suitable for use as... Figure 1 At least a portion of the reflection-reducing element 122 of the augmented reality system 100.

[0085] exist Figure 14 In this configuration, the top 1406 of the nanostructure may lack a region that is generally flat and parallel to the plane of the edge surface 120. The effective refractive index at the top 1406 of the nanostructure can be substantially equal to the refractive index of air.

[0086] As another configuration of the reflection-reducing element 122, the anti-reflection structure can be laser-patterned directly on the edge surface 120 of the waveguide 102.

[0087] As understood by those skilled in the art of nanofabrication, such as with reference Figures 1 to 14 The described structure and method can be used to fabricate wafers to realize the fabrication of multiple diffractive waveguide combiners (DWCs) in a single operation. Each wafer can have sufficient area to accommodate multiple DWCs. (See reference...) Figures 1 to 14 The description states that each region of the wafer can be configured with etchable layers of a specific profile, which are specific to a particular DWC nanostructure arrangement.

[0088] In some examples, each wafer can be used to produce multiple identical DWCs, where the wafer is configured to have the same area with variations in thickness profile across the region of each DWC.

[0089] In other examples, each wafer can be configured to fabricate a DWC specific to a particular wavelength, such as red, green, and blue, or red, green, cyan, and violet light. In these examples, a single wafer can yield a sufficient number of DWC elements to produce the final waveguide design that includes stacked red, green, and blue, or stacked red, green, cyan, and violet-specific DWCs, enabling panchromatic imaging when light is introduced.

[0090] The wafers produced using the methods discussed above can then be used in a step-by-step repetitive nanoimprint lithography process to produce mass-produced DWC equipment.

[0091] The above detailed description includes reference to the accompanying drawings, which form a part of the detailed description. The drawings illustrate specific embodiments that can be practiced by way of illustration. These embodiments may also be referred to herein as "examples". Such embodiments or examples may include elements other than those shown or described. However, the inventors also contemplate examples in which only those elements shown or described are provided. Furthermore, the inventors contemplate examples using any combination or arrangement of those elements (or one or more aspects of those elements) shown or described with respect to a particular example (or one or more aspects of that particular example) or with respect to other examples shown or described herein (or one or more aspects of other examples). That is, the embodiments or examples described above, or one or more aspects, features, or elements thereof, may be used in combination with each other.

[0092] To further illustrate the systems and related methods disclosed herein, a non-limiting list of examples is provided below. Each of the following non-limiting examples may exist independently or may be combined with any or more of the other examples in any permutation or combination.

[0093] In Example 1, a method for reducing reflection in a waveguide may include: depositing a curable material onto a soluble film; curing the curable material on the soluble film such that the cured material forms a reduced reflectivity structure on the soluble film; dissolving the soluble film such that the reduced reflectivity structure remains intact on the dissolved film to form a reduced reflectivity film; applying a primer layer to an edge surface of the waveguide, the edge surface extending between light-guiding surfaces of the waveguide; and positioning at least a portion of the reduced reflectivity film onto the primer layer such that the primer layer adheres the reduced reflectivity film to the edge surface.

[0094] In Example 2, the method according to Example 1 may optionally be configured such that: the curing introduces shrinkage of the curable material; and the shrinkage of the curable material introduces stress in the soluble film, but not stress on the edge surface of the waveguide.

[0095] In Example 3, the method according to any one of Examples 1 to 2 may optionally be configured such that the curing includes at least one of thermal curing, ultraviolet curing, moisture curing, or oxygen curing.

[0096] In Example 4, the method according to any one of Examples 1 to 3 may optionally include: trimming the reflectivity-reducing film to have a size that substantially corresponds to the area of ​​the edge surface.

[0097] In Example 5, the method according to any one of Examples 1 to 4 may optionally be configured such that: the curable material includes an absorbent material; the reflectivity-reducing structure includes an absorbent structure; and the reflectivity-reducing film includes an absorbent film.

[0098] In Example 6, the method according to any one of Examples 1 to 5 may optionally be configured such that: the curable material comprises a photovoltaic material; the structure for reducing reflectivity comprises a photovoltaic structure; and the film for reducing reflectivity comprises a photovoltaic film.

[0099] In Example 7, the method according to any one of Examples 1 to 6 may optionally be configured such that the photovoltaic film includes: a first electrode disposed on the edge surface and at least substantially transparent at the wavelength of light guided by the waveguide; a first photovoltaic material layer disposed on the first electrode; a second photovoltaic material layer disposed on the first photovoltaic material layer, the first photovoltaic material layer and the second photovoltaic material layer being configured to convert at least a portion of the guided light striking the first photovoltaic material layer and the second photovoltaic material layer into electrical energy; and a second electrode disposed on the second photovoltaic material layer.

[0100] In Example 8, the method according to any one of Examples 1 to 7 may optionally include: storing the electrical energy in a battery, the battery being electrically connected to the first photovoltaic material layer and the second photovoltaic material layer via the first electrode and the second electrode.

[0101] In Example 9, an augmented reality system may include: a waveguide having opposing light-guiding surfaces and an edge surface extending between the opposing light-guiding surfaces, the waveguide being configured to guide guided light between the opposing light-guiding surfaces toward the edge surface; and a cured film disposed on the edge surface and configured to reduce the reflectivity of the edge surface.

[0102] In Example 10, the augmented reality system according to Example 9 may optionally be configured such that the solidified film includes an absorbent material.

[0103] In Example 11, the augmented reality system according to any one of Examples 9 to 10 may optionally be configured such that: the solidified film includes a photovoltaic film, the photovoltaic film includes a photovoltaic layer structure, the photovoltaic layer structure being configured to convert at least a portion of the guided light impacting the photovoltaic layer structure into electrical energy.

[0104] In Example 12, the augmented reality system according to any one of Examples 9 to 11 may optionally be configured such that: the photovoltaic layer structure includes: a first electrode disposed on the edge surface and at least substantially transparent at the wavelength of the light guided by the waveguide; a first photovoltaic material layer disposed on the first electrode; a second photovoltaic material layer disposed on the first photovoltaic material layer, the first photovoltaic material layer and the second photovoltaic material layer being configured to convert at least a portion of the guided light impacting the material layer into electrical energy; and a second electrode disposed on the second photovoltaic material layer.

[0105] In Example 13, an augmented reality system may include: a waveguide having opposing light-guiding surfaces and an edge surface extending between the opposing light-guiding surfaces, the waveguide being configured to guide guided light between the opposing light-guiding surfaces toward the edge surface; and a photovoltaic film disposed on the edge surface and configured to reduce the reflectivity of the edge surface, the photovoltaic film being further configured to convert at least a portion of the guided light impacting the photovoltaic film into electrical energy.

[0106] In Example 14, the augmented reality system according to Example 13 may also optionally include a battery electrically connected to the photovoltaic film and configured to store the electrical energy.

[0107] In Example 15, the augmented reality system according to any one of Examples 13 to 14 may optionally be configured such that the photovoltaic film includes: a first electrode disposed on the edge surface and at least substantially transparent at the wavelength of the guided light; a first photovoltaic material layer disposed on the first electrode; a second photovoltaic material layer disposed on the first photovoltaic material layer, the first photovoltaic material layer and the second photovoltaic material layer being configured to convert at least a portion of the guided light striking the first photovoltaic material layer and the second photovoltaic material layer into the electrical energy; and a second electrode disposed on the second photovoltaic material layer, wherein the battery is electrically connected to the first photovoltaic material layer and the second photovoltaic material layer via the first electrode and the second electrode.

[0108] In Example 16, an augmented reality system may include: a waveguide having opposing light-guiding surfaces and an edge surface extending between the opposing light-guiding surfaces, the waveguide being configured to guide guided light between the opposing light-guiding surfaces toward the edge surface, and the edge surface including a nanostructure configured to reduce the reflectivity of the edge surface.

[0109] In Example 17, the augmented reality system according to Example 16 may optionally be configured such that the nanostructure is sized to modulate the refractive index at the edge surface.

[0110] In Example 18, the augmented reality system according to any one of Examples 16 to 17 may optionally be configured such that: the nanostructure has a nanostructure bottom facing the interior of the waveguide and a nanostructure top facing away from the interior of the waveguide; the nanostructure has a material fill factor truncated in a cross-sectional plane parallel to the edge surface, the material fill factor corresponding to the proportion of a unit cross-sectional area occupied by the nanostructure, the material fill factor decreasing from the bottom of the nanostructure to the top of the nanostructure; the nanostructure defines an effective refractive index for each cross-sectional plane from the bottom of the nanostructure to the top of the nanostructure, the effective refractive index varying according to the material fill factor at the cross-sectional plane; and the effective refractive index at the bottom of the nanostructure matches the refractive index of the waveguide material of the waveguide.

[0111] In Example 19, the augmented reality system according to any one of Examples 16 to 18 may optionally be configured such that: the nanostructure is formed into a pyramid; each pyramid has a pyramid base facing the interior of the waveguide and a pyramid top facing away from the interior of the waveguide; each pyramid has a cross-sectional area intercepted in a cross-sectional plane parallel to the edge surface, the cross-sectional area decreasing monotonically from the pyramid base to the pyramid top; each pyramid defines an effective refractive index for each cross-sectional plane from the pyramid base to the pyramid top, the effective refractive index varying according to the cross-sectional area of ​​the pyramid at the cross-sectional plane; and the effective refractive index at the base of the pyramid matches the refractive index of the waveguide material of the waveguide.

[0112] In Example 20, the augmented reality system according to any one of Examples 16 to 19 may optionally be configured such that: the top of the pyramid lacks a region of generally flat planes parallel to the edge surfaces; and the effective refractive index at the top of the pyramid is substantially equal to the refractive index of air.

[0113] In the foregoing description, various embodiments of this disclosure have been presented for purposes of illustration and description. These embodiments are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in accordance with the foregoing teachings. Various embodiments were chosen and described to provide the best illustration of the principles of this disclosure and its practical application, and to enable those skilled in the art to utilize various embodiments with modifications suitable for the intended particular use. All such modifications and variations are within the scope of this disclosure as defined by the appended claims when interpreted according to their fair, lawful, and just protection.

Claims

1. A method for reducing reflections in a waveguide, the method comprising: Apply curable materials onto a soluble film; When the curable material is applied to the soluble film, the curable material is cured, such that the cured material forms a structure with reduced reflectivity on the soluble film. Dissolve the soluble film such that the reflectivity-reducing structure remains intact on the dissolved film to form a reflectivity-reducing film; A primer layer is applied to the edge surface of the waveguide, the edge surface extending between the light-guiding surfaces of the waveguide; as well as At least a portion of the anti-reflectivity film is positioned onto the primer layer such that the primer layer adheres the anti-reflectivity film to the edge surface.

2. The method according to claim 1, wherein: The curing process introduces shrinkage into the curable material; and The shrinkage of the curable material introduces stress into the soluble film, but not into the edge surface of the waveguide.

3. The method according to claim 1, wherein, The curing process includes at least one of thermal curing, ultraviolet curing, moisture curing, or oxygen curing.

4. The method according to claim 1, further comprising: The reflectivity-reducing film is modified to have a size that approximately corresponds to the area of ​​the edge surface.

5. The method according to claim 1, wherein: The curable material includes absorbent materials; The structure for reducing reflectivity includes an absorption structure; and The film that reduces reflectivity includes an absorption film.

6. The method according to claim 1, wherein: The curable material includes photovoltaic materials; The structure for reducing reflectivity includes a photovoltaic structure; and The film that reduces reflectivity includes photovoltaic films.

7. The method according to claim 6, wherein, The photovoltaic film includes: A first electrode is disposed on the edge surface and is at least substantially transparent at the wavelength of the light guided by the waveguide; A first photovoltaic material layer disposed on the first electrode; A second photovoltaic material layer disposed on the first photovoltaic material layer, wherein the first and second photovoltaic material layers are configured to convert at least a portion of the light guided onto the first and second photovoltaic material layers into electrical energy; and A second electrode disposed on the second photovoltaic material layer.

8. The method according to claim 7, further comprising: The electrical energy is stored in a battery, which is electrically connected to the first photovoltaic material layer and the second photovoltaic material layer via the first electrode and the second electrode.

9. An augmented reality system, comprising: A waveguide having opposing light-guiding surfaces and an edge surface extending between the opposing light-guiding surfaces, the waveguide being configured to guide guided light between the opposing light-guiding surfaces toward the edge surface; and A cured film disposed on the edge surface and configured to reduce the reflectivity of the edge surface.

10. The augmented reality system according to claim 9, wherein, The cured film includes an absorbent material.

11. The augmented reality system according to claim 9, wherein, The cured film includes a photovoltaic film, the photovoltaic film including a photovoltaic layered structure configured to convert at least a portion of the guided light impacting the photovoltaic layered structure into electrical energy.

12. The augmented reality system according to claim 11, wherein, The photovoltaic layered structure includes: A first electrode is disposed on the edge surface and is at least substantially transparent at the wavelength of the light guided by the waveguide; A first photovoltaic material layer disposed on the first electrode; A second photovoltaic material layer disposed on the first photovoltaic material layer, the first photovoltaic material layer and the second photovoltaic material layer being configured to convert at least a portion of the guided light impacting the material layers into electrical energy; and A second electrode disposed on the second photovoltaic material layer.

13. An augmented reality system, comprising: A waveguide having opposing light-guiding surfaces and an edge surface extending between the opposing light-guiding surfaces, the waveguide being configured to guide guided light between the opposing light-guiding surfaces toward the edge surface; and A photovoltaic film disposed on the edge surface and configured to reduce the reflectivity of the edge surface, the photovoltaic film being further configured to convert at least a portion of the guided light striking the photovoltaic film into electrical energy.

14. The augmented reality system of claim 13, further comprising a battery electrically connected to the photovoltaic film and configured to store the electrical energy.

15. The augmented reality system according to claim 14, wherein, The photovoltaic film includes: A first electrode is disposed on the edge surface and is at least substantially transparent at the wavelength of the guided light; A first photovoltaic material layer disposed on the first electrode; A second photovoltaic material layer disposed on the first photovoltaic material layer, wherein the first and second photovoltaic material layers are configured to convert at least a portion of the guided light impacting the first and second photovoltaic material layers into electrical energy; and The second electrode is disposed on the second photovoltaic material layer. The battery is electrically connected to the first photovoltaic material layer and the second photovoltaic material layer via the first electrode and the second electrode.

16. An augmented reality system, comprising: A waveguide having opposing light-guiding surfaces and edge surfaces extending between the opposing light-guiding surfaces. The waveguide is configured to direct the guided light between the opposing light-guiding surfaces toward the edge surface, and The edge surface includes nanostructures configured to reduce the reflectivity of the edge surface.

17. The augmented reality system according to claim 16, wherein, The nanostructure is sized to modulate the refractive index at the edge surface.

18. The augmented reality system according to claim 17, wherein: The nanostructure has a bottom facing the interior of the waveguide and a top facing away from the interior of the waveguide. The nanostructure has a material fill factor cut out in a cross-sectional plane parallel to the edge surface, the material fill factor corresponding to the proportion of the unit cross-sectional area occupied by the nanostructure, and the material fill factor decreasing from the bottom to the top of the nanostructure; The nanostructure defines the effective refractive index of each cross-sectional plane from the bottom to the top of the nanostructure, the effective refractive index varying according to the material fill factor at the cross-sectional plane; and The effective refractive index at the bottom of the nanostructure matches the refractive index of the waveguide material.

19. The augmented reality system according to claim 17, wherein: The nanostructure is formed into a pyramid; Each pyramid has a pyramidal base facing the interior of the waveguide and a pyramidal top facing away from the interior of the waveguide; Each pyramid has a cross-sectional area taken out in a cross-sectional plane parallel to the edge surface, the cross-sectional area decreasing monotonically from the bottom of the pyramid to the top of the pyramid; Each pyramid defines an effective refractive index for each cross-sectional plane from the base to the apex of the pyramid, the effective refractive index varying according to the cross-sectional area of ​​the pyramid at the cross-sectional plane; as well as The effective refractive index at the bottom of the pyramid matches the refractive index of the waveguide material.

20. The augmented reality system according to claim 19, wherein: The apex of the pyramid lacks a region that is generally flat and parallel to the plane of the edge surface; and The effective refractive index at the top of the pyramid is approximately equal to the refractive index of air.

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