Mixed-valence sol-gels for high refractive index transparent optical coatings

Abstract

The techniques disclosed herein relate to sol-gel materials that include at least one metal halide precursor and at least one alcohol. After annealing, the metal in the metal halide is in at least two different oxidation states, both of which are stable and transparent to visible light. By creating a mixture of the same metal in multiple oxidation states, all of which are transparent to visible light, it is possible to obtain an amorphous sol-gel material for overcoating without forming any significant domains that, if formed, would locally distribute stress and create voids in the nanolattice. The highly condensed sol-gel has a refractive index value in the range of 1.7 to 2.2 without sacrificing the filling of recessed features.

Description

[Technical field]

[0001] This disclosure relates generally to sol-gel materials (e.g., sol-gel topcoat mixtures).

[0002]

[0002] Sol-gels are materials composed of solutions containing metal oxide precursors that may be partially or fully condensed into an extended network. When a sol-gel solution is coated and thermally annealed, the precursor ligands and solvent are thermally removed and the extended network may fully condense into an oxide or inorganic film. The condensation process may result in densification and possibly crystallization. Thus, when applied to a substrate and annealed, sol-gels can be used to produce transparent, high refractive index (RI) coatings. Overview

[0003]

[0003] This disclosure generally relates to sol-gel materials (e.g., sol-gel overcoat mixtures). More specifically, the techniques disclosed herein relate to sol-gel materials that may include at least one metal halide precursor and at least one alcohol. After annealing, the metal in the metal halide can be in at least two oxidation states, both of which are stable and transparent. By creating a mixture of the same metal in multiple oxidation states, and a mixture of oxo and chloride ligands, all of which are transparent to visible light, an amorphous sol-gel material can be obtained for overcoating without forming any significant domains that, if formed, would locally distribute stress or shrink and create voids in the nanolattice. Thus, a highly condensed sol-gel can be achieved with an RI value in the range of about 1.7 to about 2.2 without sacrificing the filling of recessed features.

[0004] In one embodiment, a tin(II) precursor containing a halide ligand is dissolved in an alcohol or glycol. Upon coating and annealing, the tin(II) mixture is partially oxidized to tin(IV). Both tin(II) and tin(IV) oxides or oxyhalides are transparent to visible light, as are mixtures of the two oxidation states. Furthermore, the mixture of tin(II) and tin(IV) oxides or oxyhalides can be condensed to produce coatings that, when in an amorphous state after annealing, have an IR value of about 1.7 to about 2.2 and do not form discontinuous domains, regardless of the level of condensation. To achieve an RI value within the range of about 1.7 to about 2.2 without losing the ability to fill recessed features (e.g., fill recessed features of a substrate void-free), the tin(II):tin(IV) ratio can be maintained within the range of about 1:5 to about 4:1. Advantageously, the condensation process for sol-gel materials (eg, tin(II) / tin(IV) mixtures) can be carried out at temperatures below about 300°C.

[0005]

[0005] According to a first aspect of the present disclosure, there is provided a sol-gel material for overcoating a surface relief structure, the sol-gel material comprising: a metal halide precursor; and at least one alcohol or glycol.

[0006] In some embodiments, the metal halide precursor comprises a source of tin(II) chloride or a source of tin(II) chloride dihydrate.

[0007] In some embodiments, the sol-gel material further comprises a solvent that is a source of oxide ligands during the annealing process.

[0008]

[0008] In some embodiments, after applying an annealing treatment to the sol-gel material, the sol-gel material comprises metals in the metal halide precursor in at least two different oxidation states; the metals in the at least two different oxidation states are both transparent to visible light.

[0009] In some embodiments, after the sol-gel material is subjected to an annealing treatment, the oxychloride composition of the sol-gel material is non-stoichiometric.

[0010] In some embodiments, the metal comprises tin and the metal in at least two different oxidation states comprises tin(II) and tin(IV).

[0011]

[0011] In some embodiments, the sol-gel material is configured to fill recessed features on a substrate in a superconformal manner without creating voids upon complete thermal densification of the sol-gel material.

[0012] In some embodiments, the sol-gel material further comprises a stabilizer, an acid, a base, a peroxide, a surfactant, a crosslinker, a softener, a strengthening agent, a solvent, or a combination thereof.

[0013] In some embodiments, the stabilizer comprises ethanolamine, diethanolamine, triethanolamine, an aliphatic amine, a diamine, a triamine, a polyamine, or a combination thereof.

[0014] In some embodiments, the stabilizer comprises an organic antioxidant, an inorganic antioxidant, or a combination thereof.

[0015]

[0015] In some embodiments, the sol-gel material further comprises a solvent comprising propylene glycol methyl ether, dipropylene glycol monomethyl ether, propylene glycol methyl ether acetate, tripropylene glycol monomethyl ether, butyl lactate, propylene carbonate, isopropyl alcohol, methanol, water or a combination thereof.

[0016] In some embodiments, the sol-gel material comprises 10% to 30% by weight of a stannous salt; and 70% to 90% by weight of a solvent mixture.

[0017]

[0017] In some embodiments, the stannous salt comprises stannous chloride; stannous dichloride dihydrate; anhydrous stannous dichloride; or any combination thereof.

[0018]

[0018] In some embodiments, the solvent mixture comprises 27% by weight propylene glycol methyl ether, 67% by weight 1,3-dimethoxy-2-propanol, and 6% by weight diethylene glycol; 27% by weight propylene glycol methyl ether, 67% by weight di(propylene glycol) methyl ether, and 6% by weight diethylene glycol; or 100% by weight 1,3-dimethoxy-2-propanol.

[0019]

[0019] According to a second aspect of the present disclosure, there is provided an optical device for a display system comprising: a surface relief structure including recessed features; and a layer of a sol-gel material that fills the recessed features of the surface relief structure in a superconformal manner without creating voids, wherein the sol-gel material comprises at least two metals in different oxidation states, and the at least two metals in different oxidation states are transparent to visible light.

[0020] In some embodiments, the layer of sol-gel material has an absorption of less than 0.1% per 100 nm for visible light and a refractive index of the layer of sol-gel material is between 1.65 and 2.20.

[0021] In some embodiments, the metal in at least two different oxidation states comprises tin(II) and tin(IV).

[0022] In some embodiments, the ratio of tin(II) to tin(IV) in the layer of sol-gel material is from 1:5 to 4:1, and the sol-gel material is in an amorphous state.

[0023] In some embodiments, the surface relief structures include features characterized by widths between 5 nm and 200 nm and aspect ratios between 1:1.5 and 1:50.

[0024]

[0024] According to a third aspect of the present disclosure, there is provided a method for producing a superconformal optical coating, the method comprising depositing a layer of sol-gel material on a surface relief structure, the sol-gel material comprising: a metal halide precursor; and at least one alcohol or glycol; and annealing the layer of sol-gel material at a temperature of 300°C or less for less than about 10 minutes to superconformally fill the surface relief structure with the sol-gel material.

[0025]

[0025] This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all of the drawings, and the claims of this disclosure. The above, together with other features and examples, are described in more detail below in the subsequent specification, claims and accompanying drawings.

[0026]

[0026] It is recognized that any feature described herein as suitable for incorporation in one or more aspects or embodiments of the present disclosure is intended to be generalizable across any and all aspects and embodiments of the present disclosure. Other aspects of the present disclosure may be understood by those skilled in the art in light of the description, claims, and drawings of the present disclosure. The foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the scope of the claims.

[0027]

[0027] Illustrative aspects are described in detail below with reference to the following figures. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a simplified block diagram of an example of a virtual reality system environment including an eyepiece display according to certain aspects. [Diagram 2]

[0029] FIG. 2 is a perspective view of an example eyepiece display in the form of a head mounted display (HMD) device for implementing some of the examples disclosed herein. [Diagram 3]

[0030] FIG. 3 is a perspective view of an example eyepiece display in the form of glasses for implementing some of the examples disclosed herein. [Figure 4]

[0031] FIG. 4 illustrates an example of an optical see-through augmented reality system including a waveguide display, according to certain embodiments. [Figure 5A]

[0032] FIG. 5A illustrates an example of an eyepiece display device including a waveguide display, according to certain embodiments. [Figure 5B]

[0033] FIG. 5B illustrates an example of an eyepiece display device including a waveguide display, according to certain embodiments. [Figure 6]

[0034] FIG. 6 illustrates an example of a tilted grating in a waveguide display, according to certain embodiments. [Figure 7A]

[0035] FIG. 7A shows an example of a sol-gel coating layer on a flat substrate before and after annealing, where the sol-gel coating layer can condense and shrink during and after annealing to form domains or grains. [Figure 7B]

[0036] FIG. 7B shows a substrate containing a recessed feature and a sol-gel coating layer on the recessed feature before and after annealing, where domain formation results in voids within the recessed feature. [Figure 8A]

[0037] FIG. 8A illustrates a substrate including a sol-gel coating layer deposited thereon, the sol-gel coating layer may include a sol-gel material according to certain embodiments disclosed herein, before and after annealing. [Figure 8B]

[0038] FIG. 8B shows a substrate including a recessed feature and a sol-gel coating layer on the recessed feature before and after annealing, where the sol-gel coating layer may include a sol-gel material according to certain embodiments disclosed herein, resulting in a void-free, superconformal filling of the recessed feature. [Figure 9A]

[0039] FIG. 9A shows the compositions and performance of the materials of Comparative Examples 1-3. [Figure 9B]

[0040] FIG. 9B shows cross-sectional views of examples of surface relief gratings having coating layers formed in Comparative Examples 1-3 under a scanning electron microscope (SEM). [Figure 10A]

[0041] FIG. 10A shows the composition and performance of the materials of Examples 4-10, according to certain embodiments. [Figure 10B]

[0042] FIG. 10B shows a cross-sectional view (e.g., by SEM) of an example surface relief grating having a superconformal overcoat layer formed in Examples 4-10, according to certain embodiments. [Figure 11]

[0043] FIG. 11 shows the composition and performance of the materials of Examples 11-12, according to certain embodiments. [Figure 12A]

[0044] FIG. 12A shows the composition and performance of the materials of Examples 13-17, according to certain embodiments. [Figure 12B]

[0045] FIG. 12B shows cross-sectional views (eg, by SEM) of example surface relief gratings having the superconformal overcoat layers formed in Examples 13-15 and the coating layers formed in Examples 16-17 according to certain embodiments. [Figure 13]

[0046] FIG. 13 shows the composition and performance of the materials of Examples 18-20, according to certain embodiments. [Figure 14]

[0047] FIG. 14 shows the composition and performance of the materials of Examples 21-22, according to certain embodiments. Detailed Description

[0029]

[0048] The figures depict embodiments of the present disclosure for purposes of explanation only. Those skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods described may be employed without departing from the principles of this disclosure or its intended benefit.

[0030]

[0049] In the accompanying figures, similar components and / or features may have the same reference numbers. Furthermore, various components of the same type may be distinguished by following the reference number with a dash and a second number that distinguishes between the similar components. When only a first reference number is used in the specification, the description applies to any of the similar components having the same first reference number, regardless of the second reference number.

[0031]

[0050] This disclosure generally relates to sol-gel overcoat materials. More specifically, the techniques disclosed herein relate to sol-gel materials that include a mixture of the same metal (e.g., tin(II) and tin(IV)) in multiple oxidation states, all of which are transparent, and the sol-gel material can remain amorphous without forming any significant domains. When used in optical coatings, the sol-gel material can achieve a highly condensed state with RI values ​​in the range of about 1.7 to 2.2 without sacrificing filling of recessed features. Various aspects of the invention are described herein, including devices, systems, methods, materials, processes, and compositions.

[0032]

[0051] An artificial reality system, e.g., a head mounted display (HMD) or head up display (HUD) system, typically includes an ocular display configured to present content to a user via an electronic or optical display, e.g., within about 10-20 mm in front of the user's eyes. The ocular display may be in the form of, e.g., a headset or glasses. The ocular display may display virtual objects or combine images of real objects with virtual objects, for virtual reality (VR), augmented reality (AR) or mixed reality (MR) applications. For example, in an AR system, a user may see both images of virtual objects (e.g., computer generated imagery (CGI)) and the surrounding environment, e.g., by looking through transparent display glasses or lenses (often referred to as optical see-through).

[0033]

[0052] An example of an optical see-through AR system may use a waveguide-based optical display, where the light of the projected image may be coupled into a waveguide (e.g., a transparent substrate), propagate through the waveguide through total internal reflection, and be coupled out of the waveguide at multiple points toward the user's eye. In some implementations, the light of the projected image may be coupled into or out of the waveguide using a diffractive optical element, e.g., a diffraction grating, which may be transparent to ambient light, so that light from the surrounding environment may pass through the see-through region of the waveguide to reach the user's eye without being diffracted. In some implementations, a surface relief grating comprising a surface relief structure formed in a substrate or a material layer deposited on a substrate may be used to couple light into or out of the waveguide. An overcoat layer having a refractive index different from that of the surface relief structure may be formed on the surface relief grating to fill gaps in the surface relief structure and mediate the optical properties of the surface relief structure. The overcoat layer may need to be superconformal to the surface of the surface relief structure, free of voids or bubbles, have a refractive index much higher or lower than that of the surface relief structure, and have low absorption for visible light. The overcoat layer may comprise a dielectric material such as hafnia, titania, tantalum oxide, tungsten oxide, zirconium oxide, gallium sulfide, gallium nitride, gallium phosphide, silicon, or a high refractive index organic material (e.g., a resin).

[0034]

[0053] According to certain embodiments, sol-gels may be used to form an overcoat layer on a surface relief diffraction grating. Sol-gels are materials that may include solutions containing oxide precursors, which may be partially or completely condensed into an extended network. When the sol-gel is coated and thermally annealed, the ligands and solvent of the precursors are removed, and the extended network may be completely condensed into an oxide or inorganic film. The condensation process may result in densification, and in some circumstances, crystallization. Thus, when applied to a substrate and annealed, sol-gels can be used to produce high refractive index (RI) coatings. Sol-gels can be delivered as solutions, and therefore may offer improved processability compared to high RI nanocomposites, which may have high viscosity and reduced material flowability. Furthermore, because sol-gels do not require the incorporation of a resin matrix, and because annealing can drive all organic and solvent components out of the oxide or inorganic network, sol-gels may also offer the advantage of high RI coatings with improved transparency to visible light, as compared to nanocomposites that contain high RI nanoparticles dispersed in a resin and whose transparency may deteriorate over time. However, for sol-gels applied as coatings for optical diffraction gratings, it is desirable for the coating to soak into the recessed features (gratings, grooves, vias, and through-holes) and retain a flat surface on top of the coating. In other words, the coating must achieve superconformal feature filling. Although sol-gels may fill these features prior to annealing and densification, typical oxide densification to obtain RI values ​​greater than about 1.7 has been found to produce voids in nanolattices, typically with feature widths of 5-200 nm and aspect ratios (width to depth) of about 1:1.5 to about 1:50.

[0035]

[0054] Void formation can occur during condensation if the shrinkage stress is not distributed evenly throughout the film or if the stress does not act unidirectionally and prevents escape from the nanolattice. It has been found that the stress is distributed locally within domains or grains in the nanolattice and void formation can occur around these domains as the material shrinks. Therefore, to avoid the formation of domains or grains or to distribute the shrinkage stress throughout the sol-gel coating, it is desirable to maintain a continuous material network. This may be achieved by maintaining the sol-gel material in an amorphous state. However, in most cases, it is unlikely that the material can be condensed to achieve an RI higher than 1.7 without forming discontinuous domains in the sol-gel or causing some level of crystallization. Furthermore, it is desirable to fill recessed features in a void-free manner without the need to increase the organic content in the sol-gel content. Surfactants and auxiliary organic resins can be mixed into the sol-gel to improve saturation of the features and retention of the fill during shrinkage and to avoid discontinuous grain formation. However, increasing the organic content in the coating typically reduces the transparency of the coating or potentially creates reliability issues. Thus, a new class of sol-gel materials is needed that can achieve high RI (e.g., about 1.7-2.2) and void-free superconformal filling of recessed features after annealing (e.g., after curing). In addition, to increase the compatibility and utilization of sol-gel materials in industrial manufacturing processes, there is a need for sol-gel materials that can be condensed to achieve high RI values ​​at annealing temperatures below about 300°C.

[0036]

[0055] Sol-gel coatings are typically used to form conformal coatings that follow the topography of the underlying featureless substrate. In most of these applications, the sol-gel coating is only non-uniform in two dimensions, but the thickness (third dimension) is constant (see, for example, Barhoum et al., Chem. Mater. 2011, 23, 23, 5177-5184; Yan et al., Electrochimica Acta 2015, 169, 73-81; and Lu et al., Nano Letters 2002, 2, 3, 183-186). Although the shape of the substrate may be complex (i.e., flat, curved, cylindrical, etc.), the substrate typically does not contain nanometer-scale recessed features. In situations where the substrate has nano- to micro-sized recessed features with high aspect ratios, the sol-gel is expected to follow the contours of the features and form a conformal coating. High aspect ratio features can be filled with non-annealed films if the film thickness is greater than the depth of the recessed features. Nevertheless, upon annealing, the sol-gel material can shrink and collapse into particulates inside high aspect ratio nano- to micro-sized recessed features, resulting in holes or voids. As a result, sol-gel is not typically used for superconformal coating of high aspect ratio recessed features. In this disclosure, sol-gel materials are disclosed that can produce a flat surface on top of the sol-gel coating while superconformally filling within high aspect ratio recessed features.

[0037]

[0056] The annealing temperature for full densification of sol-gel coatings generally depends on the chemistry of the precursors used and the structure of the target oxide, but the annealing temperature is typically higher than about 500° C. For example, full densification of TiO2 films made from monomeric precursors is observed at about 600° C. (see Taherniya et al., Mater. Res. Express 2019, 6, 016417; and Tanski et al., BULLETIN OF THE POLISH ACADEMY OF SCIENCES TECHNICAL SCIENCES, Vol. 66, No. 2, 2018, DOI: 10.24425 / 119069). Annealing treatments are used to maximize the RI and tune the transparency of the film (see Blanco et al., Applied Surface Science 2018, 439, 736-748; and Gareso et al., 2019 J.Phys.:Conf.Ser.1242 012037). In many cases, the shrinkage from the initial coating to the fully annealed film is greater than 60%, and typically around 90% (see Lodh & Chakraborty, Bandgap Engineering of Sol-Gel Spin-Coated TiO2Thin Film on Glass Substrate. 2021, DOI:10.1201 / 9781003047193-2). Thus, films made from sol-gels can have large thickness variations during annealing, and applications to fill recessed features can involve void formation in the features due to shrinkage.

[0038]

[0057] Sol-gels containing multicore precursors, or precondensed gels, can be used to reduce the shrinkage of the film between coating and full annealing. However, the compositions of these materials are typically unstable and tend to form nanoparticles in solution over time (see Sano et al., ACS Appl. Mater. Interfaces 2020, 12, 40, 44743-44753). Furthermore, molecular oxide clusters tend to destabilize and move toward water and molecular oxygen, or to condense over time (see Matthews et al., Chem. Commun. 2014, 50, 12815-12823; Coppens et al., Chem. Rev. 2014, 114, 9645-9661; and Rozes et al., Chem. Soc. Rev. 2011, 40, 1006-1030). Once condensed and nanoparticles are formed, high quality superconformal filling of recessed features may not be achieved without a supplemental resin, and therefore the applicability of polyoxoclusters in industrial applications may be severely hindered.

[0039]

[0058] Titanium oxysulfate-based sol-gels may be used to achieve and maintain the filling of recessed features throughout the sol-gel annealing process. Sulfate ions may prevent the material from forming particles during the condensation process, thus preventing void formation. However, titanium oxysulfate-based sol-gels may only enable optical films with a maximum RI of about 1.95. For example, when titanium oxysulfate is used as the sole precursor in the sol-gel, the maximum RI of the resulting coating is about 1.81. The RI may be further increased by mixing the titanium oxysulfate precursor with a precondensed network from a secondary oxytitanyl species or titanium tetrachloride precursor. The mixing ratio between titanium oxysulfate and the second titanium species may determine the balance between optical performance and the ability to fill recessed features. However, it may be difficult to increase the RI above 1.95 without losing the ability to fill recesses. This is because high ratios of the second oxytitanyl or titanium tetrachloride precursor may not prevent premature particle and void formation during shrinkage.

[0040]

[0059] Filling of recessed features with RI up to 2.0 may be possible with two-component titanium systems annealed at temperatures below 500°C. This may be achieved by delaying the formation of domains or grains until the very final stages of condensation, so that even if localized shrinkage does occur, no significant voids result. However, this capability cannot be extended to coatings with RIs higher than 2.0, and processing temperatures below 300°C may only produce coatings with RIs lower than 1.9.

[0041]

[0060] Therefore, there is a need for a sol-gel material that can be used to create coatings that superconformally fill recessed features with feature widths of about 5-200 nm and aspect ratios of width to depth of about 1:1.5-1:50, and have a sol-gel RI of about 1.7-2.2 when the sol-gel is processed at temperatures below about 300° C.

[0042]

[0061] The technical solution disclosed herein provides a sol-gel material that can form a coating layer with a high RI (e.g., about 1.7 to 2.2) after annealing and can superconformally fill nano- to micro-sized surface relief structures on a surface. In some embodiments, the sol-gel material may include at least one metal halide precursor and at least one alcohol. After annealing, the metal in the metal halide can be in at least two oxidation states, both of which are stable and transparent. By creating a mixture of the same metal in multiple oxidation states, and a mixture of oxo and chloride ligands, all transparent to visible light, an amorphous sol-gel material can be obtained for overcoating without forming any significant domains that, if formed, would locally distribute stress or shrink and create voids in the nanolattice. Thus, a highly condensed sol-gel with an RI value in the range of about 1.7 to about 2.2 can be achieved without sacrificing the filling of recessed features.

[0043]

[0062] In the following description, for purposes of explanation, specific details are set forth to provide a thorough understanding of the examples of the present disclosure. However, it is clear that various examples may be practiced without these specific details. For example, devices, systems, structures, assemblies, methods, and other components may be shown as components in block diagram form so as not to obscure the examples in unnecessary detail. In other instances, well-known devices, methods, systems, structures, and techniques may be shown without necessary details so as to avoid obscuring the examples. The figures and descriptions are not intended to be limiting. The terms and expressions used in this disclosure are used as terms of description and not of limitation, and the use of such terms and expressions is not intended to exclude any equivalents of the features shown and described, or portions thereof. The word "example" is used herein to mean "serving as an example, instance, or illustration." Any aspect or design described herein as an "example" should not necessarily be construed as preferred or advantageous over other aspects or designs.

[0044]

[0063] FIG. 1 is a simplified block diagram of an example of a synthetic reality system environment 100 including an eyepiece display 120, according to certain embodiments. The synthetic reality system environment 100 shown in FIG. 1 may include an eyepiece display 120, an optional external imaging device 150, and an optional input / output interface 140, each of which may be coupled to an optional console 110. Although FIG. 1 shows an example of a synthetic reality system environment 100 including one eyepiece display 120, one external imaging device 150, and one input / output interface 140, the synthetic reality system environment 100 may include any number of these components, or any of the components may be omitted. For example, there may be multiple eyepiece displays 120 monitored by one or more external imaging devices 150 in communication with the console 110. In some configurations, the synthetic reality system environment 100 may not include the external imaging device 150, the optional input / output interface 140, and the optional console 110. In alternative configurations, different or additional components may be included in the synthetic reality system environment 100.

[0045]

[0064] The eyepiece display 120 may be a head-mounted display that presents content to a user. Examples of content presented by the eyepiece display 120 include one or more of images, video, and audio, or any combination thereof. In some embodiments, audio may be presented via an external device (e.g., a speaker and / or headphones) that receives audio information from the eyepiece display 120, the console 110, or both, and presents audio data based on the audio information. The eyepiece display 120 may include one or more rigid bodies that may be rigidly or non-rigidly coupled to each other. A rigid coupling between the rigid bodies may cause the coupled rigid bodies to act as a single rigid entity. A non-rigid coupling between the rigid bodies may allow the rigid bodies to move relative to each other. In various embodiments, the eyepiece display 120 may be implemented in any suitable form factor, including glasses. Some embodiments of the eyepiece display 120 are further described below with respect to FIGS. 2 and 3. Additionally, in various aspects, the functionality described herein may be used in a headset that combines artificial reality content (e.g., computer-generated imagery) with images of an environment external to the eyepiece display 120. Thus, the eyepiece display 120 may augment images of an actual real-world environment external to the eyepiece display 120 with generated content (e.g., images, video, or sound) to present an augmented reality to the user.

[0046]

[0065] In various embodiments, the eyepiece display 120 may include one or more of the display electronics 122, the display optics 124, and the eye tracking unit 130. In some embodiments, the eyepiece display 120 may also include one or more locators 126, one or more position sensors 128, and an inertial measurement unit (IMU) 132. In various embodiments, the eyepiece display 120 may omit any of the eye tracking unit 130, the locator 126, the position sensor 128, and the IMU 132, or may include additional elements. Additionally, in some embodiments, the eyepiece display 120 may include elements that combine the functionality of the various elements described in conjunction with FIG. 1.

[0047]

[0066] The display electronics 122 may display or facilitate the display of images to a user, for example, according to data received from the console 110. In various aspects, the display electronics 122 may include one or more display panels, such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, an inorganic light emitting diode (ILED) display, a micro light emitting diode (μLED) display, an active matrix OLED display (AMOLED), a transparent OLED display (TOLED), or some other display. For example, in one implementation of the eyepiece display 120, the display electronics 122 may include a front TOLED panel, a rear display panel, and optical components (e.g., attenuators, polarizers, or diffractive or spectroscopic films) between the front and rear display panels. The display electronics 122 may include pixels that emit light in base colors, for example, red, green, blue, white, or yellow. In some implementations, the display electronics 122 may display three-dimensional (3D) images through a stereoscopic effect produced by a two-dimensional panel, resulting in a subjective perception of image depth. For example, the display electronics 122 may include a left display and a right display positioned in front of a user's left and right eyes, respectively. The left and right displays may present copies of an image that are horizontally shifted relative to each other to create a stereoscopic effect (i.e., the perception of image depth by a user viewing the image).

[0048]

[0067] In certain embodiments, the display optics 124 may optically display image content (e.g., using optical waveguides and combiners), magnify image light received from the display electronics 122, correct optical errors related to the image light, and present the corrected image light to a user of the eyepiece display 120. In various embodiments, the display optics 124 may include one or more optical elements, such as a substrate, an optical waveguide, an aperture, a Fresnel lens, a convex lens, a concave lens, a filter, an input / output combiner, or any other suitable optical element that may affect the image light emitted from the display electronics 122. The display optics 124 may include a combination of different optical elements, as well as mechanical couplings to maintain the relative spacing and orientation of the optical elements in the combination. One or more optical elements in the display optics 124 may have an optical coating, such as an anti-reflective coating, a reflective coating, a filtering coating, or a combination of different optical coatings.

[0049]

[0068] Magnification of image light by the display optics 124 allows the display electronics 122 to be physically smaller, lighter, and consume less power than larger displays. Additionally, magnification may increase the field of view of the displayed content. The amount of magnification of image light by the display optics 124 may be changed by adjusting, adding, or removing optical elements from the display optics 124. In some embodiments, the display optics 124 may project the displayed image onto one or more image planes that may be further away from the user's eyes than the eyepiece display 120.

[0050]

[0069] The display optics 124 may also be designed to correct one or more types of optical errors, such as two-dimensional optical errors, three-dimensional optical errors, or any combination thereof. Two-dimensional errors may include optical aberrations occurring in two dimensions. Exemplary types of two-dimensional errors may include barrel distortion, pincushion distortion, on-axis chromatic aberration, and off-axis chromatic aberration. Three-dimensional errors may include optical errors occurring in three dimensions. Exemplary types of three-dimensional errors may include spherical aberration, coma, field curvature, and astigmatism.

[0051]

[0070] The locators 126 may be objects placed at specific locations on the eyepiece display 120 relative to each other and to reference points on the eyepiece display 120. In some implementations, the console 110 may identify the locators 126 in images captured by the external imaging device 150 to determine the location, orientation, or both of the artificial reality headset. The locators 126 may be LEDs, corner cube reflectors, reflective markers, a type of light source that contrasts with the environment in which the eyepiece display 120 operates, or any combination of these. In aspects in which the locators 126 are active elements (e.g., LEDs, or other types of light emitting devices), the locators 126 may emit light in the visible band (e.g., about 380 nm to 750 nm), in the infrared (IR) band (e.g., about 750 nm to 1 mm), in the ultraviolet band (e.g., about 10 nm to about 380 nm), in another portion of the electromagnetic spectrum, or in any combination of portions of the electromagnetic spectrum.

[0052]

[0071] External imaging device 150 may include one or more cameras, one or more video cameras, any other device capable of capturing an image including one or more of locators 126, or any combination thereof. Additionally, external imaging device 150 may include one or more filters (e.g., to increase the signal-to-noise ratio). External imaging device 150 may be configured to detect light emitted or reflected from locators 126 in the field of view of external imaging device 150. In aspects in which locators 126 include passive elements (e.g., retroreflectors), external imaging device 150 may include a light source that illuminates some or all of locators 126, which may retroreflect light back to the light source within external imaging device 150. Slow calibration data may be communicated from the external imaging device 150 to the console 110, and the external imaging device 150 may receive one or more calibration parameters from the console 110 to adjust one or more imaging parameters (e.g., focal length, focus, frame rate, sensor temperature, shutter speed or aperture).

[0053]

[0072] The position sensor 128 may generate one or more measurement signals in response to movement of the eyepiece display 120. Examples of the position sensor 128 may include an accelerometer, a gyroscope, a magnetometer, other motion detection or error correction sensors, or any combination thereof. For example, in some embodiments, the position sensor 128 may include multiple accelerometers for measuring translational movement (e.g., forward / backward, up / down, or left / right) and multiple gyroscopes for measuring rotational movement (e.g., pitch, yaw, or roll). In some embodiments, the various position sensors may be oriented orthogonal to one another.

[0054]

[0073] The IMU 132 may be an electronic device that generates fast calibration data based on measurement signals received from one or more of the position sensors 128. The position sensors 128 may be located external to the IMU 132, internal to the IMU 132, or any combination thereof. Based on one or more measurement signals from the one or more position sensors 128, the IMU 132 may generate fast calibration data indicating an estimated position of the eyepiece display 120 relative to an initial position of the eyepiece display 120. For example, the IMU 132 may integrate measurement signals received from an accelerometer over time to estimate a velocity vector, and may integrate the velocity vector over time to determine an estimated position of a reference point on the eyepiece display 120. Alternatively, the IMU 132 may provide spot measurement signals to the console 110, which may determine the fast calibration data. Although a reference point may generally be defined as a point in space, in various aspects the reference point may be defined as a point within the eyepiece display 120 (e.g., the center of the IMU 132).

[0055]

[0074] The eye tracking unit 130 may include one or more eye tracking systems. Eye tracking may refer to determining the position of the eye, including the orientation and point of the eye, relative to the eyepiece display 120. The eye tracking system may include an imaging system for imaging one or more eyes, and may optionally include a light emitter, which may generate light toward the eye, so that the light reflected by the eye may be captured by the imaging system. For example, the eye tracking unit 130 may include a non-coherent or coherent light source (e.g., a laser diode) that emits light in the visible or infrared spectrum, and a camera that captures the light reflected by the user's eye. As another example, the eye tracking unit 130 may capture reflected radio waves emitted by a small radar unit. The eye tracking unit 130 may use a low-power light emitter that emits light at a frequency and intensity that does not damage the eye or cause physical discomfort. The eye tracking unit 130 may be arranged to increase contrast in the eye images captured by the eye tracking unit 130 while reducing the overall power consumed by the eye tracking unit 130 (e.g., while reducing the power consumed by the light emitters and imaging systems included in the eye tracking unit 130). For example, in some implementations, the eye tracking unit 130 may consume less than 100 milliwatts of power.

[0056]

[0075] The eyepiece display 120 may use eye orientation, for example, to determine the user's interpupillary distance (IPD), to determine gaze direction, to introduce depth cues (e.g., blurred images outside the user's primary line of sight), to correct heuristics regarding the user's interference in the VR medium (e.g., time spent on any particular subject, object, or frame as a function of the stimuli exposed), some other function based in part on the orientation of at least one of the user's eyes, or any combination of these. Since orientations may be determined for both of the user's eyes, the eye tracking unit 130 may be able to determine where the user is looking. For example, determining the direction of the user's gaze may include determining a point of convergence based on the determined orientation of the user's left eye and right eye. The point of convergence may be a point where the two foveal axes of the user's eyes intersect. The direction of the user's gaze may be a direction in which a line passes through the point of convergence and the midpoint between the pupils of the user's eyes.

[0057]

[0076] The input / output interface 140 may be a device through which a user sends action requests to the console 110. The action request may be a request to perform a particular action. For example, the action request may be to start or close an application or to perform a particular action within an application. The input / output interface 140 may include one or more input devices. Exemplary input devices may include a keyboard, a mouse, a game controller, gloves, buttons, a touch screen, or any other suitable device for receiving action requests and communicating the received action requests to the console 110. The action requests received by the input / output interface 140 may be communicated to the console 110, which may perform an action corresponding to the requested action. In some aspects, the input / output interface 140 may provide haptic feedback to the user according to instructions received from the console 110. For example, the input / output interface 140 may provide haptic feedback when an action request is received or when the console 110 performs the requested action and communicates the instructions to the input / output interface 140. In some embodiments, the external imaging device 150 may be used to track the input / output interface 140, e.g., to track the point or position of a controller (which may include, e.g., an IR light source) or a user's hand to determine user movement. In some embodiments, the eyepiece display 120 may include one or more imaging devices to track the input / output interface 140, e.g., to track the point or position of a controller or a user's hand to determine user movement.

[0058]

[0077] The console 110 may provide content to the eyepiece display 120 for presentation to a user according to information received from one or more of the external imaging device 150, the eyepiece display 120, and the input / output interface 140. In the example shown in FIG. 1, the console 110 may include an application store 112, a headset tracking module 114, a virtual reality engine 116, and an eye tracking module 118. Some embodiments of the console 110 may include different or additional modules than those described in conjunction with FIG. 1. Functionality described further below may be distributed among components of the console 110 in ways different from those described herein.

[0059]

[0078] In some aspects, the console 110 may include a processor and a non-transitory computer-readable storage medium that stores instructions executable by the processor. The processor may include multiple processing units that execute instructions in parallel. The non-transitory computer-readable storage medium may be any memory, such as a hard disk drive, a removable memory, or a solid-state drive (e.g., flash memory or dynamic random access memory (DRAM)). In various aspects, the modules of the console 110 described in conjunction with FIG. 1 may be encoded as instructions in the non-transitory computer-readable storage medium that, when executed by the processor, cause the processor to perform functions as described further below.

[0060]

[0079] The application store 112 may store one or more applications for execution by the console 110. An application may include a set of instructions that, when executed by the processor, generates content for presentation to a user. The content generated by an application may be responsive to input received from a user via the user's eye movements or input received from the input / output interface 140. Examples of applications may include gaming applications, conferencing applications, video playback applications, or other suitable applications.

[0061]

[0080] The headset tracking module 114 may use the slow calibration information from the external imaging device 150 to track the movement of the eyepiece display 120. For example, the headset tracking module 114 may use the locators observed from the slow calibration information and a model of the eyepiece display 120 to determine the location of a reference point on the eyepiece display 120. The headset tracking module 114 may also use position information from the fast calibration information to determine the location of a reference point on the eyepiece display 120. Additionally, in some aspects, the headset tracking module 114 may use a portion of the fast calibration information, the slow calibration information, or any combination thereof, to predict a future point of the eyepiece display 120. The headset tracking module 114 may provide an estimated or predicted future position of the eyepiece display 120 to the virtual reality engine 116.

[0062]

[0081] The virtual reality engine 116 may execute an application within the virtual reality system environment 100 and may receive position information of the eyepiece display 120, acceleration information of the eyepiece display 120, velocity information of the eyepiece display 120, a predicted future position of the eyepiece display 120, or any combination thereof, from the headset tracking module 114. The virtual reality engine 116 may also receive estimated eye position and orientation information from the eye tracking module 118. Based on the received information, the virtual reality engine 116 may determine content to provide to the eyepiece display 120 for presentation to the user. For example, if the received information indicates that the user was looking left, the virtual reality engine 116 may generate content for the eyepiece display 120 that reflects the user's eye movements in the virtual environment. Additionally, the virtual reality engine 116 may perform an action in an application executing on the console 110 in response to an action request received from the input / output interface 140 and may provide feedback to the user indicating that the action was performed. The feedback may be visual or audio feedback via the eyepiece display 120, or tactile feedback via the input / output interface 140.

[0063]

[0082] The eye tracking module 118 may receive eye tracking data from the eye tracking unit 130 and determine the position of the user's eyes based on the eye tracking data. The eye position may include the eye orientation, the point, or both, or any of these, relative to the eyepiece display 120. Determining the eye point within the eye socket may enable the eye tracking module 118 to more accurately determine the eye orientation, since the axis of rotation of the eye varies as a function of the eye point within the eye socket.

[0064]

[0083] FIG. 2 is a perspective view of an example of an eyepiece display in the form of an HMD device 200 for implementing some of the examples disclosed herein. The HMD device 200 may be part of, for example, a VR system, an AR system, an MR system, or any combination thereof. The HMD device 200 may include a body 220 and a head strap 230. FIG. 2 shows a bottom side 223, a front side 225, and a left side 227 of the body 220 in a perspective view. The head strap 230 may have an adjustable or extendable length. There may be sufficient space between the body 220 and the head strap 230 of the HMD device 200 for a user to wear the HMD device 200 on the user's head. In various embodiments, the HMD device 200 may include additional, fewer, or different components. For example, in some embodiments, the HMD device 200 may include eyeglass temples and temple tips rather than the head strap 230, as shown, for example, in FIG. 3 below.

[0065]

[0084] The HMD device 200 may present media to the user, including virtual and / or augmented views of the actual real-world environment using computer-generated elements. Examples of media presented by the HMD device 200 may include images (e.g., two-dimensional (2D) or three-dimensional (3D) images), video (e.g., 2D or 3D video), audio, or any combination thereof. The images and video may be presented to each eye of the user by one or more display assemblies (not shown in FIG. 2 ) enclosed in the body 220 of the HMD device 200. In various embodiments, the one or more display assemblies may include a single electronic display panel, or multiple electronic display panels (e.g., one display panel for each eye of the user). Examples of electronic display panels may include, for example, LCD, OLED display, ILED display, μLED display, AMOLED, TOLED, some other display, or any combination thereof. The HMD device 200 may include two eyebox regions.

[0066]

[0085] In some implementations, the HMD device 200 may include various sensors (not shown), such as depth sensors, motion sensors, position sensors, and eye-tracking sensors. Some of these sensors may use structured light patterns for sensing. In some implementations, the HMD device 200 may include an input / output interface for communicating with a console. In some implementations, the HMD device 200 may include a virtual reality engine (not shown) that may execute applications within the HMD device 200 and may receive depth information, position information, acceleration information, velocity information, predicted future position, or any combination thereof, of the HMD device 200 from the various sensors. In some implementations, the information received by the virtual reality engine may be used to generate signals (e.g., display instructions) to one or more display assemblies. In some implementations, the HMD device 200 may include locators (not shown, e.g., locator 126) that are installed at fixed positions relative to each other and to reference points on the body 220. Each of the locators may emit light that is detectable by an external imaging device.

[0067]

[0086] FIG. 3 is a perspective view of an example eyepiece display 300 in the form of glasses for implementing some of the examples disclosed herein. The eyepiece display 300 may be a specific implementation of the eyepiece display 120 of FIG. 1 and may be configured to operate as a virtual reality display, an augmented reality display, and / or a mixed reality display. The eyepiece display 300 may include a frame 305 and a display 310. The display 310 may be configured to present content to a user. In some aspects, the display 310 may include display electronics and / or display optics. For example, as described above for the eyepiece display 120 of FIG. 1, the display 310 may include an LCD display panel, an LED display panel, or an optical display panel (e.g., a waveguide display assembly).

[0068]

[0087] The eyepiece display 300 may further include various sensors 350a, 350b, 350c, 350d, and 350e on or within the frame 305. In some embodiments, the sensors 350a-350e may include one or more depth sensors, motion sensors, position sensors, inertial sensors, or ambient light sensors. In some embodiments, the sensors 350a-350e may include one or more image sensors configured to generate image data corresponding to different fields of view in different directions. In some embodiments, the sensors 350a-350e may be used as input devices to control or affect the display content of the eyepiece display 300 and / or to provide an interactive VR / AR / MR experience to a user of the eyepiece display 300. In some embodiments, the sensors 350a-350e may also be used for stereoscopic imaging.

[0069]

[0088] In some embodiments, the eyepiece display 300 may further include one or more illuminators 330 for projecting light into the real environment. The projected light may relate to various frequency bands (e.g., visible light, infrared light, or ultraviolet light) and may serve various purposes. For example, the illuminator 330 may project light in a dark environment (or in an environment with low intensity infrared light, ultraviolet light, etc.) to assist the sensors 350a-350e in capturing images of various objects in the dark environment. In some embodiments, the illuminator 330 may be used to project a certain light pattern onto objects in the environment. In some embodiments, the illuminator 330 may be used as a locator, for example, the locator 126 described above with respect to FIG. 1.

[0070]

[0089] In some embodiments, the eyepiece display 300 may also include a high-resolution camera 340. The camera 340 may capture images of the real environment within the field of view. The captured images may be processed, for example, by a virtual reality engine (e.g., the virtual reality engine 116 of FIG. 1 ) to add virtual objects to the captured images or to modify real objects in the captured images, and the processed images may be displayed to a user by the display 310 for AR or MR applications.

[0071]

[0090] FIG. 4 illustrates an example of an optical see-through augmented reality system 400 including a waveguide display, according to certain embodiments. The augmented reality system 400 may include a projector 410 and a combiner 415. The projector 410 may include a light source or image source 412 and projector optics 414. In some embodiments, the light source or image source 412 may include one or more micro-LED devices as described above. In some embodiments, the light source 412 may include a plurality of pixels, e.g., an LCD display panel or an LED display panel, that display a virtual object. In some embodiments, the image source 412 may include a light source that generates coherent or partially coherent light. For example, the image source 412 may include laser diodes, vertical cavity surface emitting lasers, LEDs, and / or micro-LEDs as described above. In some embodiments, the image source 412 may include a plurality of light sources (e.g., an array of micro-LEDs as described above), each emitting monochromatic image light corresponding to a primary color (e.g., red, green, or blue). In some embodiments, the image source 412 may include three two-dimensional arrays of micro-LEDs, where each two-dimensional array of micro-LEDs may include micro-LEDs configured to emit light of a primary color (e.g., red, green, or blue). In some embodiments, the image source 412 may include an optical pattern generator, e.g., a spatial light modulator. The projector optics 414 may include one or more optical components that can condition the light from the image source 412, e.g., magnify, collimate, scan, or project the light from the image source 412 toward the combiner 415. The one or more optical components may include, e.g., one or more lenses, liquid lenses, mirrors, apertures, and / or diffraction gratings. For example, in some embodiments, the image source 412 may include one or more one-dimensional arrays or elongated two-dimensional arrays of micro-LEDs, and the projector optics 414 may include one or more one-dimensional scanners (e.g., micromirrors or prisms) configured to scan the one-dimensional arrays or elongated two-dimensional arrays of micro-LEDs to generate an image frame.In some embodiments, the projector optics 414 may include a liquid lens (eg, a liquid crystal lens) having a number of electrodes that enable the light from the image source 412 to be scanned.

[0072]

[0091] The combiner 415 may include an input coupler 430 for coupling light from the projector 410 into a substrate 420 of the combiner 415. The combiner 415 may transmit light in a first wavelength range, for example, visible light from about 400 nm to about 650 nm. The input coupler 430 may include a volume holographic grating, a diffractive optical element (DOE) (e.g., a surface relief grating), a tilted surface of the substrate 420, or a refractive coupler (e.g., a wedge or prism). For example, the input coupler 430 may include a reflective volume Bragg grating or a transmissive volume Bragg grating. The input coupler 430 may have a coupling efficiency of greater than 30%, greater than 50%, greater than 75%, greater than 90% or higher for visible light. The light coupled into the substrate 420 may propagate within the substrate 420, for example, through total internal reflection (TIR). The substrate 420 may be in the form of a lens for eyeglasses. The substrate 420 may have a flat or curved surface and may comprise one or more types of dielectric or semiconductor materials, such as glass, quartz, plastic, polymer, poly(methyl methacrylate) (PMMA), crystal, silicon, SiN, silicon carbide, or ceramic. The thickness of the substrate may range, for example, from less than about 1 mm to about 10 mm or more. The substrate 420 may be transparent to visible light.

[0073]

[0092] The substrate 420 may include or be coupled to a plurality of output couplers 440, each of which is configured to extract at least a portion of the light guided by and propagating through the substrate 420 and direct the extracted light 460 to an eye box 495, where an eye 490 of a user of the augmented reality system 400 may be located when the augmented reality system 400 is in use. The plurality of output couplers 440 may replicate the exit pupil and increase the size of the eye box 495, so that the displayed image appears to be a large area. The input couplers 430, the output couplers 440 may include a grating coupler (e.g., a volume holographic grating or a surface relief grating), other diffractive optical elements, or prisms. For example, the output coupler 440 may include a reflective volume Bragg grating or a transmissive volume Bragg grating. The output couplers 440 may have different coupling (e.g., diffraction) efficiencies at different points. The substrate 420 may also pass light 450 from the environment in front of the combiner 415 with little or no loss. The output coupler 440 may also pass light 450 with little loss. For example, in some implementations, the output coupler 440 may have a very low diffraction efficiency for the light 450, so that the light 450 may refract or otherwise pass through the output coupler 440 with little loss, and thus the light 450 may have a higher intensity than the extracted light 460. In some implementations, the output coupler 440 may have a high diffraction efficiency for the light 450 and may diffract the light 450 in a certain desired direction (i.e., diffraction angle) with little loss. As a result, a user may be able to see a combined image of the environment in front of the combiner 415 and an image of a virtual object projected by the projector 410.

[0074]

[0093] FIG. 5A illustrates an example of an eyepiece display (NED) device 500 including a waveguide display 530, according to certain embodiments. The NED device 500 may be an example of an eyepiece display 120, an augmented reality system 400, or another type of display device. The NED device 500 may include a light source 510, projection optics 520, and a waveguide display 530. The light source 510 may include a panel of multiple light emitters for different colors, for example, a panel 512 of red light emitters, a panel 514 of green light emitters, and a panel 516 of blue light emitters. The red light emitters 512 are organized in an array; the green light emitters 514 are organized in an array; and the blue light emitters 516 are organized in an array. The dimensions and pitch of the light emitters in the light source 510 may be small. For example, each light emitter may have a diameter of less than 2 μm (e.g., about 1.2 μm), and the pitch may be less than 2 μm (e.g., about 1.5 μm). As described above, the number of light emitters in each of the red light emitters 512, green light emitters 514 and blue light emitters 516 can be equal to or greater than the number of pixels in the display image, for example, 960×720, 1280×720, 1440×1080, 1920×1080, 2160×1080 or 2560×1080 pixels. Thus, the display image may be generated simultaneously by the light source 510. In the NED device 500, a scanning element may not be used.

[0075]

[0094] Prior to reaching the waveguide display 530, the light emitted by the light source 510 may be conditioned by projection optics 520, which may include a lens array. The projection optics 520 may collimate or focus the light emitted by the light source 510 towards the waveguide display 530, which may include a coupler 532 for coupling the light emitted by the light source 510 into the waveguide display 530. The light coupled into the waveguide display 530 may propagate within the waveguide display 530, for example, through total internal reflection, as described above with respect to FIG. 4. The coupler 532 may also decouple a portion of the light propagating within the waveguide display 530 out of the waveguide display 530 and towards the user's eye 590.

[0076]

[0095] FIG. 5B illustrates an example of an eyepiece display (NED) device 550 including a waveguide display 580, according to certain embodiments. In some embodiments, the NED device 550 may use a scanning mirror 570 to project light from a light source 540 onto an image field where a user's eye 590 may be located. The NED device 550 may be an example of an eyepiece display 120, an augmented reality system 400, or another type of display device. The light source 540 may include one or more rows or one or more columns of different colored light emitters, for example, multiple rows of red light emitters 542, multiple rows of green light emitters 544, and multiple rows of blue light emitters 546. For example, the red light emitters 542, the green light emitters 544, and the blue light emitters 546 may each include N rows, with each row including, for example, 2560 light emitters (pixels). The red light emitters 542 are organized in an array; the green light emitters 544 are organized in an array; and the blue light emitters 546 are organized in an array. In some embodiments, the light source 540 may include a single line of light emitters for each color. In some embodiments, the light source 540 may include multiple rows of light emitters for each of the red, green, and blue colors, with each row including, for example, 1080 light emitters. In some embodiments, the dimensions and / or pitch of the light emitters in the light source 540 may be relatively large (e.g., about 3-5 μm), and thus the light source 540 may not include enough light emitters to simultaneously generate the entire display image. For example, the number of light emitters for a single color may be less than the number of pixels in the display image (e.g., 2560×1080 pixels). The light emitted by the light source 540 may be a set of collimated or diverging beams of light.

[0077]

[0096] Prior to reaching the scanning mirror 570, the light emitted by the light source 540 may be conditioned by various optical devices, such as a collimating lens or a freeform optical element 560. The freeform optical element 560 may include, for example, a multi-faceted prism or another light folding element that may, for example, direct the light emitted by the light source 540 towards the scanning mirror 570 by changing the direction of propagation of the light emitted by the light source 540, for example, by about 90° or more. In some embodiments, the freeform optical element 560 may be rotatable to scan the light. The scanning mirror 570 and / or the freeform optical element 560 may reflect and project the light emitted by the light source 540 towards the waveguide display 580, which may include a coupler 582 for coupling the light emitted by the light source 540 into the waveguide display 580. Light coupled into waveguide display 580 may propagate within waveguide display 580, for example, through total internal reflection, as described above for Figure 4. Coupler 582 may also couple a portion of the light propagating within waveguide display 580 out of waveguide display 580 and toward a user's eye 590.

[0078]

[0097] Scanning mirror 570 may include a microelectromechanical system (MEMS) mirror or any other suitable mirror. Scanning mirror 570 may rotate to scan in one or two dimensions. As scanning mirror 570 rotates, light emitted by light source 540 may be directed to different regions of waveguide display 580 such that in each scanning cycle, the entire display image may be projected onto waveguide display 580 and directed by waveguide display 580 to a user's eye 590. For example, in embodiments where light source 540 includes light emitters for all pixels in one or more rows or columns, scanning mirror 570 may rotate in a column or row direction (e.g., in an x ​​or y direction) to scan the image. In embodiments where light source 540 includes light emitters for some but not all pixels in one or more rows or columns, scanning mirror 570 may rotate in both a column direction and a row direction (e.g., in both an x ​​and y direction) to project the display image (e.g., using a raster-type scanning pattern).

[0079]

[0098] The NED device 550 may operate for a predefined display period. The display period (e.g., display cycle) may refer to the duration of time that an entire image is scanned or projected. For example, the display period may be the inverse of a desired frame rate. In a NED device 550 that includes a scanning mirror 570, the display period may also be referred to as a scanning period or a scanning cycle. Light generation by the light source 540 may be synchronized with the rotation of the scanning mirror 570. For example, each scanning cycle may include multiple scanning steps, and the light source 540 may generate a different light pattern for each scanning step.

[0080]

[0099] As the scanning mirror 570 rotates in each scanning cycle, a display image may be projected onto the waveguide display 580 and the user's eye 590. The actual color value and light intensity (e.g., brightness) of a given pixel point of the display image may be the average of the three color (e.g., red, green, and blue) light beams that illuminate that pixel point during the scanning period. After the scanning period is completed, the scanning mirror 570 may return to its initial position to project light for the first few rows of the next display image, or may rotate in the opposite direction or scan the pattern to project light for the next display image, where a new set of drive signals may be provided to the light source 540. As the scanning mirror 570 rotates in each scanning cycle, the same process may be repeated. Thus, different images may be projected to the user's eye 590 in different scanning cycles.

[0081]

[0100] FIG. 6 illustrates an example of a tilted grating 620 in a waveguide display 600, according to certain embodiments. The tilted grating 620 may be an example of an input coupler 430, an output coupler 440, a coupler 532, or a coupler 582. The tilted grating 620 may be formed on a waveguide 610, such as a substrate 420. The tilted grating 620 may act as a grating coupler to couple light into or out of the waveguide 610. In some embodiments, the tilted grating 620 may include a one-dimensional periodic structure having a period p. For example, the tilted grating 620 may include a plurality of ridges 622 and grooves 624 between the ridges 622. Each period of the tilted grating 620 may include a ridge 622 and an air gap or a refractive index n g2The ratio between the width d of the ridges 622 and the grating period p may be referred to as the duty cycle. The tilted grating 620 may have a duty cycle, for example, in the range of about 10% to about 90% or more. In some embodiments, the duty cycle may vary with time. In some embodiments, the period p of the tilted grating may vary with area on the tilted grating 620 or may vary with the period in the tilted grating 620 (i.e., chirp). In some embodiments, the height of the ridges 622 or the depth of the grooves 624 may vary with area on the tilted grating 620 or may vary with the period in the tilted grating 620. In some embodiments, the tilted grating 620 may include a two-dimensional grating. In some embodiments, the period p, duty cycle, height of the ridges 622 and / or depth of the grooves 624 of the tilted grating 620 may vary along the x-direction, the y-direction, or both.

[0082]

[0101] The raised portion 622 is g1 Materials having a refractive index of 0.1 to 0.5, such as silicon-containing materials (e.g., SiO2, Si3N4, SiC, SiO x N y or amorphous silicon), organic materials (e.g., spin-on carbon (SOC), or amorphous carbon layer (ACL), or diamond-like carbon (DLC)), or inorganic metal oxide layers (e.g., TiO x , AlO x , TaO x or HfO x). Each ridge 622 may include a leading end 626 having a slope angle α, and a trailing end 628 having a slope angle β. In some embodiments, leading end 626 and trailing end 628 of each ridge 622 may be parallel to one another. In other words, slope angle α is approximately equal to slope angle β. In some embodiments, slope angle α may be different from slope angle β. In some embodiments, slope angle α may be approximately equal to slope angle β. For example, the difference between slope angle α and slope angle β may be less than 20%, less than 10%, less than 5%, less than 1%, or less than that. In some embodiments, slope angle α and slope angle β may be, for example, within a range of about 30° or less to about 60° or more.

[0083]

[0102] In some embodiments, the grooves 624 between the ridges 622 may be overcoated and filled with an overcoat layer 630. The overcoat layer 630 has a refractive index n g2 For example, in some embodiments, a high refractive index material, such as hafnia, titania, tantalum oxide, tungsten oxide, zirconium oxide, gallium sulfide, gallium nitride, gallium phosphide, silicon, sol-gel, high refractive index polymer, or combinations thereof, may be used to fill the grooves 624. In some embodiments, a low refractive index material, such as silicon oxide, alumina, porous silica, or a fluorinated low refractive index monomer (or polymer), may be used to fill the grooves 624. As a result, the difference between the refractive index of the ridges and the refractive index of the grooves may be greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.5, greater than 1.0, or greater. In some embodiments, the top surface of the overcoat layer 630 may be flush with the top surface of the ridges 622. In some embodiments, the top surface of the overcoat layer 630 may be above the top surface of the ridges 622.

[0084]

[0103] In some embodiments, sol-gels may be used to form an overcoat layer on a surface relief diffraction grating. Sol-gels are materials that may include solutions containing oxide precursors that may be partially or completely condensed into an extended network. When the sol-gel is coated and thermally annealed, the ligands and solvent of the precursors are removed and the extended network may be completely condensed into an oxide film. The condensation process may result in densification and, in some circumstances, crystallization. Thus, when applied to a substrate and annealed, sol-gels can be used to produce high refractive index (RI) coatings. Sol-gels can be delivered as solutions and therefore may provide improved processability compared to high RI nanocomposites that have high viscosity and reduced material flowability. Furthermore, because sol-gels do not require the incorporation of a resin matrix, and because all organic and solvent components can be driven out of the oxide network by annealing, sol-gels may also offer the advantage of high RI coatings with significantly improved transparency to visible light, compared to nanocomposites that contain high RI nanoparticles dispersed in a resin and whose transparency may deteriorate over time.

[0085]

[0104] 7A and 7B illustrate the challenges that can arise from the presence of sol-gel. FIG. 7A shows an example of a sol-gel coating layer 702 using existing sol-gel material on a flat substrate 701 before and after annealing, where the sol-gel coating layer 702 can condense and shrink during and after annealing. FIG. 7B shows a substrate 710 including nano- to micro-sized recessed features 724 (e.g., having a period of about 100 nm, hereafter also referred to as "recessed features" 724) and a sol-gel coating layer 720 on the recessed features 724 before and after annealing. As shown by FIG. 7B, if the thickness of the sol-gel coating layer 720 is greater than the depth of the recessed features 724 before annealing, the high aspect ratio features (e.g., recessed features 724) can be filled with a non-annealed film (e.g., sol-gel coating layer 720 before annealing). However, after annealing (eg, densification), voids 730 may form within recessed feature 724 due to shrinkage of the sol-gel and aggregation that may form nanoparticles or microparticles.

[0086]

[0105] FIG. 8A shows a substrate including a sol-gel coating layer 802 deposited on a substrate 801 before and after annealing, where the sol-gel coating layer 802 may include a sol-gel material according to certain embodiments disclosed herein. In the illustrated example, the sol-gel material may include a metal precursor in an initial oxidation state (+n) (e.g., before annealing); either or both of an alkoxide and halide ligand; and an oxidizing environment during annealing that oxidizes a fraction of the metal precursor to a second oxidation state (+m), thereby obtaining an amorphous mixture of the same metal in at least two different oxidation states after annealing. The amorphous mixture includes a mixture of oxide and / or halide ligands. The sol-gel material may include a mixture where the oxidizing species is either molecular oxygen, peroxide, alcohol, alkoxide, or glycol. After annealing, the sol-gel material may contain a condensed mixture of metals in different oxidation states, which may be permeable in the presence of either or both of the alkoxide and halide ligands.

[0087]

[0106] 8B illustrates a substrate 810 including nano- to micro-sized recessed features 824 (e.g., having a period of about 100 nm, hereafter also referred to as "recessed features" 824) and a sol-gel coating layer 820 over the recessed features before (e.g., sol-gel coating layer 820-1) and after (e.g., sol-gel coating layer 820-2) annealing, which may include a sol-gel material (e.g., shown in FIG. 8A) according to certain embodiments disclosed herein. By creating a mixture of the same metal in multiple oxidation states, where all of the metals in the oxidation states are permeable and the mixture includes oxide and / or halide ligands, an amorphous state can be obtained without forming any significant domains that, if formed, would locally distribute stress, shrink, and create voids in the nanolattice (e.g., sol-gel coating layer 820-2). This allows one to achieve highly condensed sol-gels with RI values ​​in the range of 1.7 to 2.2 without sacrificing recessed feature filling.

[0088]

[0107] In some embodiments, a tin(II) precursor containing a halide ligand may be dissolved in an alcohol or glycol. Upon annealing, the tin(II) mixture is partially oxidized to tin(IV). Both tin(II) and tin(IV) oxides or oxyhalides are transparent to visible light, as are mixtures of the two oxidation states. Furthermore, mixtures of tin(II) and tin(IV) oxides or oxyhalides can be condensed to produce coatings that are amorphous and have IR values ​​of about 1.7 to about 2.2, and do not form discontinuous domains, regardless of the level of condensation. The tin(II):tin(IV) ratio can be maintained within a range of about 1:5 to about 4:1 to achieve RI values ​​within a range of about 1.7 to about 2.2 without losing the ability to fill recessed features. Advantageously, the condensation process for the tin(II) / tin(IV) mixture can be carried out at temperatures below about 300°C.

[0089]

[0108] In some embodiments, the sol-gel solution may include at least one tin(II) halide precursor, and the solvent may include one or more alcohols or glycols, an optional secondary oxo donor, such as a peroxide, and an optional tin(II) stabilizer. In some embodiments, the solution may also contain an acid, a base, and / or a surfactant. The type of solvent or solvent mixture may be adjusted to produce a coating having an RI of 1.7 to 2.2 after annealing. In some embodiments, the sol-gel material may be coated onto a substrate by applying a solution containing the sol-gel material onto the substrate by spin coating, dip coating, spray coating, inkjet printing, screen printing, or contact printing, and then the substrate with the sol-gel material may be thermally annealed by at least one thermal annealing step (e.g., annealing at an annealing temperature of less than 300° C.). By applying the sol-gel materials disclosed herein, any recessed features in a substrate (e.g., nano- or micro-sized recessed features) can be coated superconformally and void-free even after the film formed by the sol-gel material is fully densified. Specifically, the film remains in an amorphous state throughout the densification process.

[0090]

[0109] In some embodiments, the sol-gel material may include at least one metal halide precursor and at least one alcohol, and the metal halide is used to form a superconformal optical coating on a surface having nano-sized recessed features. Upon thermal annealing, the sol-gel material may produce a coating of metal oxychlorides, where the metal exists in at least two different oxidation states. After annealing, the resulting sol-gel coating may have a non-stoichiometric oxychloride composition. In some embodiments, in the resulting sol-gel coating, the mixture of different oxidation states of the metal oxychlorides is transparent to visible light (e.g., has an absorbance of less than 0.1% / 100 nm). In some embodiments, the solvent of the sol-gel material may serve as a source of oxide ligands, at least in part, during thermal curing (e.g., annealing). Specifically, in the sol-gel material, the metal halide source may be tin(II) chloride. In some embodiments, after annealing, the ratio of tin(II) to tin(II) in the sol-gel material is 1:5 to 4:1. The ratio can be adjusted by controlling the annealing temperature, the identity of the solvent and / or the solvent mixture. After annealing, the condensed coating is in an amorphous state.

[0091]

[0110] In some embodiments, the sol-gel material, when coated on a substrate having recessed features, can be annealed at temperatures of 300° C. or less for less than 10 minutes to achieve a coating with an RI of 1.7 to 2.2. After the annealing process, the sol-gel material can fill the recessed features on the substrate in a superconformal manner without voids. In some embodiments, the sol-gel material may optionally include stabilizers, acids, bases, peroxides, surfactants, crosslinkers, softeners and strengtheners, and / or solvents. In some embodiments, the stabilizer additive can optionally be one of ethanolamine, diethanolamine, triethanolamine, aliphatic amines, diamines, triamines, or polyamines. In some other embodiments, the stabilizer additive can be one or a mixture of organic or inorganic antioxidants. In some embodiments, the solvent additive of the sol-gel material may optionally be one or a mixture of propylene glycol methyl ether (PGME), dipropylene glycol monomethyl ether (DPGME), propylene glycol methyl ether acetate, tripropylene glycol monomethyl ether, butyl lactate, propylene carbonate, isopropyl alcohol (e.g., 1,3-dimethoxy-2-propanol), methanol, and water.

[0092]

[0111] According to certain embodiments, the method may include applying a sol-gel material made by dissolving or suspending at least one metal chloride precursor in a solvent comprising at least one alcohol onto a substrate having recessed features, and annealing the sol-gel material at a temperature of 300° C. or less to produce mixed valence metal oxychlorides and achieve superconformal filling of the recessed features with the sol-gel material. In some embodiments, the annealing may be performed in a single step or multiple steps, and the single step or multiple step annealing may have an annealing temperature of 300° C. or less and a total annealing time of 10 minutes or less. When the sol-gel material is applied to a substrate to superconformally fill recessed features in the substrate, the recessed features may be gratings, trenches, vias and / or through-holes having feature widths of 5-200 nm and width-to-depth aspect ratios of 1:1.5-1:50. The final thickness of the coating on the top surface of the coated substrate may be less than 50 nm, and the recessed features may be completely filled in a void-free manner with the annealed sol-gel material. In some embodiments, the sol-gel material may be applied onto the substrate to form an optical coating by spin coating, dip coating, spray coating, inkjet printing, screen printing, or contact printing. The cured (e.g., annealed) sol-gel coating (e.g., a film layer formed by the sol-gel material) may have a RI of 1.65 to 2.20 and a visible light absorbance of less than 0.1% / 100 nm after densification of the coating.

[0093] [example] I. Comparative Examples 1-3

[0112] FIG. 9A shows the composition and performance of the materials of Comparative Examples 1-3. FIG. 9B shows the cross-sections (e.g., by SEM) of examples of surface relief diffraction gratings with coating layers formed in Comparative Examples 1-3 under a microscope. As shown in FIG. 9A and 9B, in Comparative Example 1, titanium (IV) tetrachloride was dissolved in DPGME solvent. The resulting sol-gel was coated on a silicon substrate cleaned by oxygen gas plasma. The substrate contained nano-sized grooves in the range of 15-100 nm width and 220 nm depth. The substrate was then annealed at 150° C., and the thickness and RI of the sol-gel coating were measured by ellipsometry. As shown in FIG. 9A, the RI of the film was found to be 1.64. Furthermore, a cross-section of the substrate was obtained to determine the quality of groove filling by the sol-gel by SEM. It was found that the sol-gel did not fill the grooves. Instead, the grooves were only partially filled and contained voids. More specifically, the sol-gel appears to contain particle aggregates, despite a low level of densification, corresponding to an RI value of 1.64. This result illustrates the correlation between the inability of traditional sol-gel materials to remain particulate-free throughout the annealing process and the inability to achieve superconformal filling of nano-sized features. Furthermore, mixtures of titanium(IV) with other oxidation states of titanium cannot be formed, as the other available oxidation states of titanium are not stable under ambient conditions or are colored in the visible spectrum.

[0094]

[0113] In Comparative Example 2, hafnium(IV) tetrachloride was dissolved in DPGME solvent. The resulting sol-gel was coated onto silicon substrates that had been cleaned by oxygen gas plasma. The substrates contained nano-sized grooves ranging from 15-100 nm in width and 220 nm in depth. The substrates were then annealed at 150°C, and the thickness and RI of the sol-gel coating were measured by ellipsometry. As shown in Figure 9A, the RI of the film was found to be 1.57. Additionally, cross-sections of the substrates were obtained to determine the quality of the groove filling by the sol-gel by SEM. It was found that the sol-gel did not fill the grooves. Instead, the grooves were only partially filled and contained voids. More specifically, the sol-gel deposits appear to contain particle aggregates, despite a low level of densification corresponding to an RI value of 1.57. This result illustrates the correlation between the inability of traditional sol-gel materials to remain particulate-free throughout the annealing process and the inability to achieve superconformal filling of nano-sized features. Furthermore, mixtures of hafnium(IV) with other oxidation states of hafnium cannot be formed because the other available oxidation states of titanium are not stable under ambient conditions or are colored in the visible spectrum.

[0095]

[0114] In Comparative Example 3, niobium pentachloride (V) was dissolved in DPGME solvent. The resulting sol-gel was coated onto silicon substrates that had been cleaned by oxygen gas plasma. The substrates contained nano-sized grooves ranging from 15-100 nm in width and 220 nm in depth. The substrates were then annealed at 150°C, and the thickness and RI of the sol-gel coating were measured by ellipsometry. As shown in Figure 9A, the RI of the film was found to be 1.72. Additionally, a cross-section of the substrate was obtained to determine the quality of the groove filling by the sol-gel by SEM. It was found that the sol-gel did not fill the grooves. Instead, the grooves were only partially filled and contained voids. More specifically, the sol-gel deposits appear to contain particle aggregates, despite a low level of densification corresponding to an RI value of 1.72. This result illustrates the correlation between the inability of traditional sol-gel materials to remain particulate-free throughout the annealing process and the inability to achieve superconformal filling of nano-sized features. Furthermore, mixtures of niobium(V) with other oxidation states of niobium cannot be formed because the other available oxidation states of titanium are not stable under ambient conditions or are colored in the visible spectrum.

[0096] II. Examples 4-10

[0115] Figure 10A shows the composition and performance of the materials of Examples 4-10, and Figure 10B shows cross-sectional views of examples of surface relief gratings with superconformal overcoat layers formed in Examples 4-10 under a microscope (e.g., SEM) according to certain embodiments. Examples 4-10 reveal the relationship between the RI of the coating (e.g., RI of 1.6 to 2.2) and the annealing temperature.

[0097]

[0116] As detailed in FIG. 10A, in Examples 4-10, tin(II) dichloride was dissolved in DPGME until a final tin(II) chloride concentration of 10 wt% was reached. The resulting sol-gel was coated onto silicon substrates cleaned by oxygen gas plasma. The substrates contained nano-sized grooves ranging from 15-100 nm in width and 220 nm in depth. The substrates were then annealed at temperatures ranging from 80-200°C, and the thickness and RI of the sol-gel coating were measured by ellipsometry. As shown in FIG. 10A, it was found that the RI of the film varied from 1.59 to 2.12 as the shrinkage of the film increased with increasing annealing temperature. Furthermore, cross-sections of the substrates were obtained and the quality of the groove filling by the sol-gel was determined by SEM. It was found that the sol-gel coating penetrated the entirety of all the grooves, and remained inside the grooves even after annealing and shrinkage. Even in cases 9-10 where the final coating shrunk below the top surface of the nanogratings, the sol-gel still exhibits superconformal bottom-up filling behavior. Finally, the sol-gel was coated onto a fused silica substrate. The substrate was then annealed at temperatures ranging from 80-200 °C, and the absorbance of the sol-gel coating was measured by spectrophotometry. In all cases, the absorbance of the film was found to remain less than 0.1%. Collectively, these results illustrate that tin(II) precursors containing halide and alcohol ligands can be used to form highly transparent, high RI coatings with the ability to fill recessed features.

[0098] III. Examples 11-12

[0117] FIG. 11 shows the composition and performance of the materials of Examples 11-12 according to certain embodiments. As detailed in FIG. 11, in Examples 11-12, tin(II) dichloride was dissolved in DPGME until a final tin(II) chloride concentration of 10 wt% was reached. The resulting sol-gel was coated onto a fused silica substrate. The substrate was then annealed at temperatures between 150° C. and 185° C. The crystallinity of the coating was then determined by X-ray diffraction (XRD). As shown in FIG. 11, it was found that none of the annealing temperatures resulted in any measurable crystallinity. This is consistent with the SEM data from Experiments 8 and 9, where the sol-gel deposit appears continuous and amorphous. Furthermore, the composition of the sol-gel coating was investigated by surface X-ray photoelectron spectroscopy (XPS). In both cases, the material was found to be tin oxychloride with mixed tin(II) / tin(IV) oxidation states. As shown in Figure 11, the ratio of Sn(II) increases as the temperature increases, consistent with the observation in Figure 10A that the measured RI also increases as the temperature increases. Collectively, these results indicate that in the formulations of the present invention, the precursors are partially oxidized to give a mixture of metal oxidation states and ligand types. This mixture, in turn, allows for highly condensed films with high RI that are still amorphous, and thus can preserve the filling of recessed features in the nanopattern.

[0099] IV. Examples 13-17

[0118] FIG. 12A shows the composition and performance of the materials of Examples 13-17, and FIG. 12B shows a cross-sectional view (e.g., by SEM) of an example of a surface relief grating with a superconformal overcoat layer formed in Examples 13-15 and a coating layer formed in Examples 16-17 under a microscope according to certain embodiments. As detailed in FIG. 12A, in Examples 13-15, tin(II) dichloride was dissolved in either isopropanol, diethylene glycol, or propylene glycol methyl ether until a final tin(II) chloride concentration of 10% by weight was reached. The resulting sol-gel was coated on a silicon substrate cleaned by oxygen gas plasma. The substrate contained nano-sized grooves in the range of 15-100 nm in width and 220 nm in depth. The substrate was then annealed at a temperature of 200° C., and the RI of the sol-gel was measured by ellipsometry. The RI was found to vary depending on the solvent selected. The choice of solvent can alter the balance between the tin(II) and tin(IV) content and the ability of the solvent to act as an oxo-donor, and therefore the degree of densification that the film undergoes. Additionally, cross-sections of the substrates were obtained and the quality of the sol-gel groove filling was determined by SEM. The sol-gel coating was found to have penetrated throughout all of the grooves and to have remained inside the grooves even after annealing and shrinkage. All sol-gel deposits appeared to be continuous and amorphous. Collectively, these results indicate that the solvent can be altered to tune the composition and optical properties of the resulting sol-gel coating without sacrificing its ability to fill recessed features.

[0100]

[0119] As detailed in FIG. 12A, in Examples 16-17, tin(II) dichloride was dissolved in either dipropylene glycol butyl ether or diethylene glycol methyl ethyl ether until a final tin(II) chloride concentration of 10 wt% was reached. The resulting sol-gel was coated onto silicon substrates that had been cleaned by oxygen gas plasma. The substrates contained nano-sized grooves ranging from 15-100 nm in width and 220 nm in depth. The substrates were then annealed at a temperature of 200° C., and the RI of the sol-gel was measured by ellipsometry. It was found that the RI varied depending on the solvent selected, with the non-alcoholic diethylene glycol methyl ethyl ether resulting in the highest RI of the set. The choice of solvent may change the balance between the tin(II) and tin(IV) content, and non-alcoholic solvents may reduce the oxidative power and therefore increase the tin(II) content and the resulting RI. Additionally, cross sections of the substrates were obtained and the quality of the groove filling by the sol-gel was determined by SEM. It was found that the sol-gel did not fill the grooves. Instead, the grooves were only partially filled and contained voids. More specifically, the sol-gel deposits appear to contain aggregates of particles. These results indicate that solvent selection has a great influence on controlling the tin(II) to tin(IV) ratio, varying the composition and densification of the film, and maintaining the amorphous continuum, which is essential for filling recessed features.

[0101] V. Examples 18-20

[0120] FIG. 13 shows the composition and performance of the materials of Examples 18-20 according to certain embodiments. As detailed in FIG. 13, in Examples 18-20, tin(II) dichloride was dissolved in propylene glycol methyl ether until a final tin(II) chloride concentration of 10 wt% was reached. The resulting sol-gel was coated onto a silicon substrate cleaned by oxygen gas plasma. The substrate contained nano-sized grooves ranging from 15-100 nm in width and 220 nm in depth. The substrate was then annealed at either 120°C, 200°C, or by a dual annealing protocol including an initial temperature of 120°C and a second temperature of 250°C. The RI of the sol-gel was then measured by ellipsometry. The final RI was found to vary depending on the annealing protocol. Specifically, the dual annealed samples were found to have a RI more similar to the single 120°C annealed sample than the single 250°C annealed sample. Initial annealing can control the ratio of tin(II) to tin(IV) and the oxide to chloride content. Subsequent annealing at high temperatures will therefore follow a different densification path compared to films directly annealed at the same high temperatures. Additionally, cross sections of the substrates were obtained and the quality of the sol-gel groove filling was determined by SEM. The sol-gel coating was found to have penetrated all of the grooves entirely and remained inside the grooves even after annealing and shrinkage. All sol-gel deposits appeared continuous and amorphous. Overall, these results indicate that the annealing protocol can be altered to tune the composition and optical properties of the resulting sol-gel coating without sacrificing its ability to fill recessed features.

[0102] VI. Examples 21-22

[0121] FIG. 14 shows the composition and performance of the materials of Examples 21-22 according to certain embodiments. As detailed in FIG. 14, in Examples 21-22, tin(II) dichloride and monoethanolamine were dissolved in dipropylene glycol methyl ether to reach final concentrations of 10% and 1% by weight, respectively. The resulting sol-gel was stored in a -20°C freezer for one week and then coated onto a silicon substrate cleaned by oxygen gas plasma. The substrate contained nano-sized grooves ranging from 15-100 nm in width and 220 nm in depth. The substrate was then annealed at either 150 or 185°C. The RI of the sol-gel was then measured by ellipsometry. It was found that the ethanolamine stabilizer had a small impact on the RI, and still could reach RI values ​​significantly above 2.0. Furthermore, cross-sections of the substrate were obtained and the quality of the groove filling by the sol-gel was determined by SEM. The sol-gel coating was found to have penetrated all of the grooves entirely and remained inside the grooves even after annealing and shrinkage. All sol-gel deposits appeared to be continuous and amorphous. Finally, the sol-gel was coated onto a fused silica substrate. The substrate was then annealed at either 150 or 200° C., and the absorbance of the sol-gel coating was measured by spectrophotometry. In both cases, the absorbance of the film was found to remain less than 0.1%. Overall, these results indicate that stabilizers can be incorporated into the sol-gel to sustain optical and recessed feature filling performance over time.

[0103]

[0122] It is understood that the compositions of the sol-gel materials described above, for example, for Figures 8A, 8B and 10A-14, are for illustrative purposes only. Other suitable compositions may be used. For example, the sol-gel material may include 10% to 30% by weight of any tin salt disclosed herein, and 70% to 90% by weight of any suitable solvent mixture disclosed herein.

[0104]

[0123] In some embodiments, in addition to or instead of the stannous salts disclosed above, the stannous salt may also include stannous dichloride dihydrate and / or anhydrous stannous dichloride. In addition to or instead of the solvent mixtures disclosed above, the solvent mixture may include about 17% to 37% by weight propylene glycol methyl ether, about 57% to 77% by weight 1,3-dimethoxy-2-propanol, and about 1% to 11% by weight diethylene glycol. Alternatively, the solvent mixture may include about 17% to 37% by weight propylene glycol methyl ether, about 57% to 77% by weight di(propylene glycol) methyl ether, and about 1% to 11% by weight diethylene glycol. Alternatively, the solvent mixture may include about 100% by weight 1,3-dimethoxy-2-propanol.

[0105]

[0124] Aspects of the present invention may include or be implemented in conjunction with a virtual reality system. A synthetic reality is a form of reality that is adjusted in some way before presentation to a user, and may include, for example, virtual reality (VR), augmented reality (AR), mixed reality (MR), hybrid reality, or some combination and / or derivative thereof. The content of the synthetic reality may include fully generated content or generated content in combination with captured (e.g., real-world) content. The content of the synthetic reality may include video, audio, haptic feedback, or some combination thereof, any of which may be presented in a single channel or in multiple channels (e.g., stereo video to create a three-dimensional effect for the viewer). Additionally, in some aspects, the synthetic reality may also relate to applications, products, accessories, services, or some combination thereof, for example, used to create content in the synthetic reality and / or otherwise used in the synthetic reality (e.g., performing activities). A virtual reality system providing virtual reality content may be implemented on a variety of platforms, including a head mounted display (MD) connected to a host computer system, a standalone HMD, a mobile device or computing system, or any other hardware platform capable of providing virtual reality content to one or more viewers.

[0106]

[0125] The methods, systems, and devices discussed above are examples. Various embodiments may omit, substitute, or add various procedures or components, as appropriate. For example, in alternative configurations, the methods described may be performed in a different order than described, and / or various steps may be added, omitted, and / or combined. Again, features described for a particular embodiment may be combined in various other embodiments. Various aspects and elements of the embodiments may be combined in a similar manner. Again, technology evolves, and thus many of the elements are examples that do not limit the scope of the disclosure to those of the specific examples.

[0107]

[0126] Specific details are given in the description to provide a thorough understanding of the aspects. However, the aspects may be practiced without these specific details. For example, well-known circuits, methods, systems, structures and techniques are shown without unnecessary detail to avoid obscuring the aspects. This description provides only example aspects and is not intended to limit the scope, applicability or configuration of the invention. Rather, the description of the preceding aspects provides a person skilled in the art with a degree of description to enable various aspects to be practiced. Various changes in the function and arrangement of elements may be made without departing from the scope of the present disclosure, as defined in the appended claims.

[0108]

[0127] Some aspects have also been described as methods depicted as flow charts or block diagrams. Although each may describe operations as a sequential method, many of the operations may be performed in parallel or simultaneously. In addition, the order of operations may be rearranged. The method may have additional steps not included in the figures. Furthermore, aspects of the methods may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware, or microcode, program code or code segments for performing the relevant tasks may be stored in a computer-readable medium, such as a storage medium. A processor may perform the relevant tasks.

[0109]

[0128] Those skilled in the art will appreciate that substantial modifications may be made in accordance with specific requirements. For example, custom or special purpose hardware may also be used, and / or particular elements may be implemented in hardware, software (including portable software, e.g. applets), or both. Furthermore, connections to other computing devices, e.g. network input / output devices, may be used.

[0110]

[0129] With reference to the accompanying figures, components that may include memory may include non-transitory machine-readable media. As used herein, the terms "machine-readable media" and "computer-readable media" refer to any storage medium that participates in providing data that causes a machine to operate in a specific manner. In the aspects provided herein above, various machine-readable media may participate in providing instructions / code to a processing unit and / or other devices for execution. Additionally or alternatively, machine-readable media may be used to store and / or transport such instructions / code. In many implementations, computer-readable media are physical and / or tangible storage media. Such media may take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Common forms of computer readable media include, for example, magnetic and / or optical media, such as compact discs (CDs) or digital versatile discs (DVDs), punch cards, paper tape, any other physical medium with a pattern of holes, RAM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), FLASH-EPROM, any other memory chip or cartridge, carrier waves as described later herein, or any other medium from which a computer can read instructions and / or code. A computer program product may include code and / or machine-executable instructions, which may correspond to a procedure, a function, a subprogram, a program, a routine, an application (App), a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements.

[0111]

[0130] Those skilled in the art will recognize that the information and signals used to communicate the messages described herein may be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0112]

[0131] The terms "and" and "or" as used herein may include a variety of meanings that are expected to depend, at least in part, on the context in which such terms are used. Typically, "or" when used to associate an enumeration, e.g., A, B, or C, is intended to mean A, B, and C, which are used herein in an inclusive sense, and A, B, or C, which are used herein in an exclusive sense. In addition, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in the singular, or may be used to describe several combinations of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example, and claimed subject matter is not limited to this example. Furthermore, the term "at least one of," when used to associate an enumeration, e.g., A, B, or C, may be interpreted to mean A, B, C, or combinations of A, B, and / or C, e.g., AB, AC, BC, AA, ABC, AAB, or AAABBCCC.

[0113]

[0132] Furthermore, although certain aspects are described using a particular combination of hardware and software, it should be recognized that other combinations of hardware and software are possible. Certain aspects may be implemented in hardware only, in software only, or using a combination thereof. In one example, the software may be implemented using a computer program product that contains computer program code or instructions executable by one or more processors to perform any or all of the steps, operations, or processes described in this disclosure, and the computer program may be stored on a non-transitory computer-readable medium. The various processes described herein may be implemented on the same processor or on different processors in any combination.

[0114]

[0133] Where a device, system, component, or module is described as being configured to perform a particular operation or function, such configuration may be accomplished, for example, by designing an electronic circuit to perform the operation, by programming a programmable electronic circuit (e.g., a microprocessor) to perform the operation, for example, by executing computer instructions or code, or by programming a processor or core that is programmed to execute code or instructions stored on a non-transitory storage medium, or any combination thereof. Processes may communicate using a variety of techniques, including, but not limited to, conventional techniques for inter-process communication, and different pairs of processes may use different techniques, or the same pair of processes may use different techniques at different times.

[0115]

[0134] The specification and drawings are therefore to be regarded in an illustrative rather than restrictive sense. However, it is apparent that additions, deductions, deletions, and other modifications and changes may be made thereto without departing from the broadest scope set forth in the claims. Thus, while specific embodiments have been described, they are not intended to be limiting. Various modifications and equivalents are intended to be encompassed within the scope of the following claims.

Claims

1. A sol-gel material, a metal halide precursor; and At least one of an alcohol and a glycol Including, The sol-gel material, wherein the metal halide precursor comprises a source of tin(II) chloride dihydrate.

2. The sol-gel material of claim 1, further comprising a solvent that is a source of oxide ligands during the annealing process.

3. after applying an annealing treatment to the sol-gel material, the sol-gel material comprises metals in the metal halide precursor in at least two different oxidation states; the metal in the at least two different oxidation states is both transparent to visible light; Optionally, after subjecting the sol-gel material to the annealing treatment, the oxychloride composition of the sol-gel material may be non-stoichiometric; Optionally, the metal may comprise tin, and the metal in at least two different oxidation states may comprise tin(II) and tin(IV). The sol-gel material according to claim 1 or 2.

4. 10. The sol-gel material of claim 1, further comprising a stabilizer, an acid, a base, a peroxide, a surfactant, a cross-linking agent, a solvent, or a combination thereof.

5. 5. The sol-gel material of claim 4, wherein the stabilizer comprises ethanolamine, diethanolamine, triethanolamine, an aliphatic amine, a diamine, a triamine, a polyamine, or a combination thereof.

6. The sol-gel material of claim 5, wherein the stabilizer comprises an organic antioxidant, an inorganic antioxidant, or a combination thereof.

7. 10. The sol-gel material of claim 1, wherein the sol-gel material further comprises a solvent comprising propylene glycol methyl ether, dipropylene glycol monomethyl ether, propylene glycol methyl ether acetate, tripropylene glycol monomethyl ether, butyl lactate, propylene carbonate, isopropyl alcohol, methanol, water, or a combination thereof.

8. The sol-gel material of claim 7, wherein the isopropyl alcohol is 1,3-dimethoxy-2-propanol.

9. The sol-gel material is 10% to 30% by weight of a stannous salt; and 70% to 90% by weight of the solvent mixture; Including, Optionally, the tin salt is tin(II) chloride; Tin dichloride dihydrate; anhydrous tin dichloride; or any combination of these; may include Optionally, the solvent mixture comprises: 27% by weight propylene glycol methyl ether, 67% by weight 1,3-dimethoxy-2-propanol, and 6% by weight diethylene glycol; 27% by weight propylene glycol methyl ether, 67% by weight di(propylene glycol) methyl ether, and 6% by weight diethylene glycol; or 100% by weight of 1,3-dimethoxy-2-propanol The sol-gel material of claim 1, wherein 10. A sol-gel material comprising: 10% to 30% by weight of a stannous salt; and 70% to 90% by weight of the solvent mixture; Including, Optionally, the tin salt is tin(II) chloride; Tin dichloride dihydrate; anhydrous tin dichloride; or any combination of these; may include the solvent mixture 27% by weight propylene glycol methyl ether, 67% by weight 1,3-dimethoxy-2-propanol, and 6% by weight diethylene glycol; 27% by weight propylene glycol methyl ether, 67% by weight di(propylene glycol) methyl ether, and 6% by weight diethylene glycol; or 100% by weight of 1,3-dimethoxy-2-propanol A sol-gel material comprising:

11. A sol-gel material comprising: 10% to 30% by weight of a stannous salt; and 70% to 90% by weight of the solvent mixture; Including, Optionally, the tin salt is tin(II) chloride; Tin dichloride dihydrate; anhydrous tin dichloride; or any combination of these; may include the solvent mixture about 17% to 37% by weight of propylene glycol methyl ether, about 57% to 77% by weight of 1,3-dimethoxy-2-propanol, and about 1% to 11% by weight of diethylene glycol A sol-gel material comprising:

Images