High elongation interface between lens and waveguide for augmented reality assembly with improved reliability

Abstract

Embodiments of the present disclosure generally relate to optical devices including a high-elongation interface material, and related methods. In one or more embodiments, an optical device, includes at least one grating over a surface of a substrate. Each grating includes a plurality of structures and one or more gap fill materials over the plurality of structures. The optical device further includes an encapsulation material over the one or more gap fill materials and a high-elongation material over the encapsulation material. The high-elongation material has an elongation greater than or equal to 20%. The optical device further includes a lens over the high-elongation material.

Description

44025507W001HIGH ELONGATION INTERFACE BETWEEN LENS AND WAVEGUIDE FOR AUGMENTED REALITY ASSEMBLY WITH IMPROVED RELIABILITY BACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to optical devices including a high-elongation interface material, and related methods.Description of the Related Art

[0002] Virtual reality is generally considered to be a computer generated simulated environment in which a user has an apparent physical presence. A virtual reality experience can be generated in 3D and viewed with a head-mounted display (HMD), such as glasses or other wearable display devices that have near-eye display panels as lenses to display a virtual reality environment that replaces an actual environment.

[0003] Augmented reality, however, enables an experience in which a user can still see through the display lenses of the glasses or other HMD device to view the surrounding environment, yet also see images of virtual objects that are generated for display and appear as part of the environment. Augmented reality can include any type of input, such as audio and haptic inputs, as well as virtual images, graphics, and video that enhances or augments the environment that the user experiences.

[0004] In addition, augmented reality can be integrated with prescription glasses, providing users with real-time overlays of information, navigation, and notifications directly in their field of vision without compromising their vision correction needs. However, building a reliable augmented reality device using prescription glasses is challenging due to the need to seamlessly integrate advanced technology while ensuring accurate vision correction and comfort for a wide range of users.

[0005] Accordingly, what is needed in the art is an augmented reality device having improved reliability and related methods.SUMMARY

[0006] Embodiments of the present disclosure generally relate to optical devices including a high-elongation interface material, and related methods.44025507W001

[0007] In one or more embodiments, an optical device, includes at least one grating over a surface of a substrate. Each grating includes a plurality of structures and one or more gap fill materials over the plurality of structures. The optical device further includes an encapsulation material over the one or more gap fill materials and a high-elongation material over the encapsulation material. The high-elongation material has an elongation greater than or equal to 20%. The optical device further includes a lens over the high-elongation material.

[0008] In one or more embodiments, an optical device includes a waveguide including a substrate with at least one grating over a surface of the substrate. The optical device further includes a high-elongation material over the waveguide. The high-elongation material has an elongation greater than or equal to 20%. The optical device further includes a lens over the high-elongation material.

[0009] In one or more embodiments, a method for forming an optical device includes etching a plurality of structures into a grating material deposited over a substrate and depositing one or more gap fill materials over the structures. The method further includes depositing an encapsulation material over the one or more gap fill materials and depositing a high-elongation material over the encapsulation material. The high-elongation material has an elongation greater than or equal to 20%. The method further includes depositing a lens over the high-elongation material.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of the disclosure and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

[0011] Figure 1 is a perspective, frontal view of a waveguide, according to one or more embodiments.

[0012] Figure 2 is a schematic side cross sectional view of an optical device, according to one or more embodiments.44025507W001

[0013] Figure 3 is a schematic side cross sectional view of the optical device, according to one or more embodiments.

[0014] Figure 4 is a schematic block diagram of a method of forming an optical device, according to one or more embodiments.

[0015] Figures 5A - 5G are schematic cross sectional views of a substrate during the method shown in Figure 4, according to one or more embodiments.

[0016] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0017] Embodiments of the present disclosure generally relate to optical devices including a high-elongation interface material, and related methods. An optical device includes a high-elongation material is disposed between a waveguide and a lens in order to prevent the optical device from getting damaged during a change in temperature due to the different thermal coefficients of the waveguide and the lens.

[0018] Figure 1 is a perspective, frontal view of a waveguide 100, according to one or more embodiments. It is to be understood that the waveguide 100 described herein is an exemplary waveguide and that other waveguides may be used with or modified to accomplish aspects of the present disclosure. The waveguide 100 includes a plurality of structures 102. The structures 102 may be disposed over, under, or on a first surface 103 of a substrate 101 or disposed in the substrate 101. The structures 102 are nanostructures have a sub-micron critical dimension, e.g., a width less than 1 micrometer. Regions of the structures 102 correspond to one or more gratings 104. Any of the grating 104 may be disposed over, under, or on the first surface 103 or over, under, or on a second surface opposing the first surface 103. In one embodiment, which can be combined with other embodiments described herein, the waveguide 100 includes at least an input coupler 104a corresponding to an input coupling grating (“input coupler”) and an output coupler 104c corresponding to an output coupling grating (“output coupler”). In another embodiment, which can be combined with other embodiments described herein, the waveguide 100 further44025507W001includes a pupil expander 104b. The pupil expander 104b corresponds to a pupil expansion grating (“Pupil Expander”) or a fold grating.

[0019] The substrate 101 can be any substrate used in the art, and can be either opaque or transparent to a chosen wavelength of light, depending for the use of the substrate 101 as a substrate for a waveguide. Substrate selection may include substrates of any suitable material, including, but not limited to, amorphous dielectrics, non-amorphous dielectrics, crystalline dielectrics, polymers, or combinations thereof. In some embodiments, the substrate 101 includes, but is not limited to, a silicon-containing material, a silicon and oxygen containing compound, a germanium-containing material, a indium and phosphide containing compound, a gallium and arsenic containing compound, a gallium and nitrogen containing compound, a carbon-containing material, a silicon and carbon containing compound, a silicon, carbon, and oxygen containing compound, a silicon and nitrogen containing compound, a silicon, oxygen, and nitrogen containing compound, a niobium and oxygen containing compound, and lithium, niobium, and oxygen containing compound, an aluminum and oxygen containing compound, a indium, tin, and oxygen containing compound, a titanium and oxygen containing compound, a lanthanum and oxygen containing compound, a gadolinium and oxygen containing compound, a zinc and oxygen containing compound, a yttrium and oxygen containing compound, a tungsten and oxygen containing compound, a potassium, and oxygen containing compound, a phosphorous and oxygen containing compound, a barium and oxygen containing compound, a sodium and oxygen containing compound, or combinations thereof. In other embodiments, which can be combined with other embodiments described herein, the substrate 101 includes an oxide including one or more of gadolinium, silicon, sodium, barium, potassium, tungsten, phosphorus, zinc, calcium, titanium, tantalum, niobium, lanthanum, zirconium, lithium, or yttrium containing-materials. Example materials of the substrate 101 include silicon (Si), silicon monoxide (SiO), silicon dioxide (SiC>2), silicon carbide (SiC), fused silica, diamond, quartz germanium (Ge), silicon germanium (SiGe), indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), sapphire, sapphire (AI2O3), lithium niobate (LiNbOs), indium tin oxide (ITO), lanthanum oxide (La20s), gadolinium oxide (Gd20s), zinc oxide (ZnO), yttrium oxide (Y2O3), tungsten oxide (WO3), titatium oxide (TiO2), zirconium oxide (ZrOs), sodium oxide (Na2O), niobium oxide (Nb20s), barium oxide (BaO), potassium44025507W001oxide (K2O), phosphorus pentoxide (P2O5), calcium oxide (CaO), or combinations thereof.

[0020] The structures 102 are disposed on or over the substrate 101. The structures 102 are formed from a grating material 201 (Figure 2). The grating material 201 and the substrate 101 include a different material. The grating material 201 includes, but is not limited to, one or more oxides, carbides, or nitrides of silicon, aluminum, zirconium, tin, tantalum, zirconium, barium, titanium, hafnium, lithium, lanthanum, cadmium, niobium, or combinations thereof. Example materials of the grating material 201 include silicon carbide, silicon oxycarbide, titanium oxide, silicon oxide, vanadium oxide, aluminum oxide, aluminum-doped zinc oxide, indium tin oxide, tin oxide, zinc oxide, tantalum oxide, silicon nitride, zirconium oxide, niobium oxide, cadmium stannate, silicon oxynitride, barium titanate, diamond like carbon, hafnium oxide, lithium niobate, silicon carbon-nitride, silver, cadmium selenide, mercury telluride, zinc selenide, silver-indium-gallium-sulfur, silver-indium-sulfur, indium phosphide, gallium phosphide, lead sulfide, lead selenide, zinc sulfide, molybdenum sulfide, tungsten sulfide, or combinations thereof. In one or more embodiments, the structures are coated with a metal. In one or more embodiments, the gratings are etched directly into the substrate. In one or more embodiments, the gratings are formed of a resist polymer material.

[0021] Figure 2 is a schematic side cross sectional view of an optical device 200, according to one or more embodiments. The optical device includes the waveguide 100. The optical device 200 further includes one or more gap fill materials. For example the optical device 200 shown in Figure 2 includes a first gap fill material 203. The optical device 200 further includes an encapsulation material 205 disposed over one or more gap fill materials. The optical device 200 further includes a high-elongation material 207 disposed over the encapsulation material 205. A lens 209 is deposited over the high-elongation material 207.

[0022] The optical device 200 includes one or more gap fill materials. In one or more embodiments, such as the embodiment shown in Figure 2, the optical device includes a first gap fill material 203. The first gap fill material 203 is deposited over the grating material 201 and the structures 102. The first gap fill material 203 fills the gaps formed between each grating. The first gap fill material 203 has a refractive index from44025507W001about 1 to about 2, such as about 1.1. In one or more embodiments, the first gap fill material 203 is porous.

[0023] In one or more embodiments, the optical device 200 includes multiple gap fill materials. For example, the optical device 200 shown in Figure 3 includes the first gap fill material 203 deposited over a second gap fill material 303. The second gap fill material 303 is deposited over the grating material 201 and the structures 102. Second gap fill material 303 fills the gaps formed between each grating. The second gap fill material 303 has a refractive index from about 1 to about 2, such as about 1.7. In one or more embodiments, second gap fill material 303 is porous. The first gap fill material 203 is deposited over the second gap fill material 303. In one or more embodiments, the first gap fill material 203 and the second gap fill material 303 have different refractive indices from one another.

[0024] It should be understood that the embodiments shown in Figure 2 and Figure 3 are shown for exemplary purposes and that the optical device 200 may include any amount of gap fill materials, such as 1 gap fill material, 2 gap fill materials, 3 gap fill materials, or 4 gap fill materials. In addition, one or more gap fill materials may be deposited in any order. For example, in one or more embodiments the first gap fill material 203 is deposited over the second gap fill material 303. In one or more embodiments, the second gap fill material 303 is deposited over the first gap fill material 203. In one or more embodiments, the one or more gap fill materials have a low coefficient of thermal expansion (CTE). In one or more embodiments, the one or more gap fill materials, collectively, have a CTE less than or equal to 30 parts per million per Kelvin (ppm / K), such as a CTE from about 5 ppm / K to about 20 ppm / K.

[0025] The optical device 200 further includes an encapsulation material 205 deposited over the one or more gap fill layers. The encapsulation material 205 seals the one or more gap fill layers and protects the one or more gap fill layers from the atmosphere. In one or more embodiments, the encapsulation material 205 has a low coefficient of thermal expansion (CTE). In one or more embodiments, the encapsulation material 205 has a CTE less than or equal to 30 ppm / K, such as a CTE from about 5 ppm / K to about 20 ppm / K.

[0026] A high-elongation material 207 is deposited over the encapsulation material 205. The high-elongation material 207 includes one or more materials having a high44025507W001elongation. The high-elongation material 207 has an elongation greater than or equal to about 20%. In one or more embodiments the high-elongation material 207 includes silicone, acrylate, epoxy, polyurethane, or a combination thereof. In one or more embodiments, the high-elongation material includes polyacrylate, PDMS, polyurethane, polyether, polyester, polyolefin, epoxy, or a combination thereof.

[0027] A lens 209 is deposited over the high-elongation material 207. The lens 209 is an optical lens. In one or more embodiments, the lens 209 provides an ophthalmic correction. In one or more embodiments the lens 209 is a convex lens with an ophthalmic correction greater than 0 diopter, such as 1 diopter, such as 2 diopter. In one or more embodiments the lens 209 is a concave lens with an ophthalmic correction less than 0 diopter, such as -1 diopter, such as -2 diopter. In one or more embodiments, the lens 209 is a piano lens with no ophthalmic correction. The lens 209 is formed of an optical lens material. In one or more embodiments, the optical lens material has a high CTE. In one or more embodiments, the optical lens material has a CTE greater than or equal to 40 ppm / K, such as a CTE from about 60 ppm / K to about 80 ppm / K. In one or more embodiments, the optical lens material has a CTE from about 100 ppm / K to about 150 ppm / K. The optical lens material can include epoxy, polyacrylate, or combinations thereof.

[0028] Figure 3 is a schematic side cross sectional view of the optical device 200, according to one or more embodiments. In one or more embodiments, the optical device shown in Figure 3 is exposed to a higher temperature than the optical device 200 shown in Figure 2.

[0029] In one or more embodiments, the optical device 200 is subject to varying temperatures. For example, in one or more embodiments, the optical lens material is deposited onto the high-elongation material 207 at a deposition temperature. The deposition temperature causes the lens 209 to expand at a greater rate than the grating material 201 , the one or more gap fill materials, and the encapsulation material 205. As the lens 209 expands, an upper surface 310 of the high-elongation material 207 expands at the same rate as the lens 209. A lower surface 320 of the high-elongation material 207 expands at the same rate as the encapsulation material 205. When the lens 209 expands due to a temperature increase, the high-elongation material 207 expands with the lens 209. The high-elongation material 207 prevents44025507W001the grating material 201, the one or more gap fill materials, and the encapsulation material 205 from getting damaged or cracking as the lens expands due to the temperature increase.

[0030] Figure 4 is a schematic block diagram of a method 400 of forming an optical device, according to one or more embodiments. Figures 5A - 5G are schematic cross sectional views of a substrate 101 during the method 400 shown in Figure 4, according to one or more embodiments.

[0031] At operation 402, as shown in Figure 5A, structures 102 are formed in a grating material 201 disposed over a substrate 101. In one or more embodiments, desired portions of the grating material 201 are etched away during an etching process to form the structures 102. In one or more embodiment, the etching process is a photolithography etching process. Each structure 102 is separated from one another by a gap having a depth.

[0032] At operation 404, as shown in Figures 5B and 5C, one or gap fill materials are deposited over the grating material 201 and the structures 102. Figure 5B shows a first gap fill material 203 deposited over the grating material 201 and the structures 102. Figure 5C shows a second gap fill material 303 deposited over the grating material 201 and the structures 102. A first gap fill material 203 is deposited over the second gap fill material 303. It should be understood that although Figures 5D-5G show a substrate 101 including a first gap fill material 203, this has been done for exemplary purposes and that the method 400 can be performed with any amount of gap fill materials, such as 1 gap fill material, 2 gap fill materials, 3 gap fill materials, or 4 gap fill materials.

[0033] At operation 406, as shown in Figure 5D, an encapsulation material is deposited over the first gap fill material 203. The encapsulation material 205 seals the one or more gap fill layers and protects the one or more gap fill layers from the atmosphere.

[0034] At operation 408, as shown in Figure 5E, a high-elongation material 207 is deposited over the encapsulation material 205. In one or more embodiments, the high-elongation material 207 is deposited as a liquid. The liquid high-elongation material 207 can be deposited using a slot-die coating process, a blade coating process, a dip44025507W001coating process, a spin coating process, an inkjet deposition process, a screenprinting process, a spray coating process, or a combination thereof. After the liquid high-elongation material 207 is deposited over the encapsulation material 205, the liquid high-elongation material 207 is solidified using a thermal curing process, an ultra violet (UV) curing process, or a combination thereof. In one or more embodiments, an optically clear adhesive (OCA) tape is deposited over the encapsulation material 205. The high-elongation material 207 is deposited over the OCA tape. A lamination process is performed on the encapsulation material 205, high-elongation material 207, and the OCA tape in order to adhere the high-elongation material 207 to the encapsulation material 205.

[0035] At operation 410, as shown in Figure 5F, a lens 209 is deposited over the high-elongation material 207. In one or more embodiments, the lens 209 is deposited using a 3D printing process. During the 3D printing process, a heated nozzle extrudes the optical lens material at a deposition temperature over the high-elongation material 207. The optical lens material is deposited in thin, controlled layers according to the specifications of a 3D model, which is sliced into individual cross-sectional layers using slicing software. As each layer is printed, it fuses with the layer beneath it, gradually forming the lens 209. The deposition temperature causes the optical lens material to expand as it is deposited over the high-elongation material 207. As the optical lens material expands, the upper surface 310 of the high-elongation material 207 expands at the same rate as the optical lens material due to the relatively high elongation of the high-elongation material 207. The lower surface 320 of the high-elongation material 207 expands at the same rate at the encapsulation material 205 due to the relatively high elongation of the high-elongation material 207. The upper surface 310 expanding at the same rate as the optical lens material and the lower surface 320 expanding at the same rate as the encapsulation material 205 allows the high-elongation material 207 to adhere to both the optical lens material and the encapsulation material 205. As a result, the high-elongation material 207 prevents the grating material 201 , the one or more gap fill materials, and the encapsulation material 205 from getting damaged or cracking during the 3D printing process.

[0036] At optional operation 412, as shown in Figure 5G, a cooling operation is performed. During the cooling operation the lens 209 contracts due to the decreased temperature at a greater rate than the encapsulation material 205. As the optical lens44025507W001material contracts, the upper surface 310 of the high-elongation material 207 contracts at the same rate as the optical lens material due to the relatively high elongation of the high-elongation material 207. The lower surface 320 of the high-elongation material 207 contracts at the same rate at the encapsulation material 205 due to the relatively high elongation of the high-elongation material 207. The upper surface 310 contracting at the same rate as the lens 209 and the lower surface 320 contracting at the same rate as the encapsulation material 205 allows the high-elongation material 207 to adhere to both the lens 209 and the encapsulation material 205. The high-elongation material 207 prevents the grating material 201, the one or more gap fill materials, and the encapsulation material 205 from getting damaged or cracking during the cooling process.

[0037] Benefits of the present disclosure include an optical device with a 3D printed lens. The high-elongation material allows for a lens to be 3D printed onto a waveguide without damaging the waveguide due to thermal expansion and contraction. Benefits of the optical device described herein further include improved reliability, decreased maintenance, decreased cost, and decreased production time.

[0038] It is contemplated that one or more aspects disclosed herein may be combined. As an example, one or more aspects, features, components, operations and / or properties of the waveguide 100, the structures 102, the gratings 104, the grating material 201 , the first gap fill material 203, the second gap fill material 303, the encapsulation material 205, the high-elongation material 207, the lens 209, and / or the method 400 be combined. Moreover, it is contemplated that one or more aspects disclosed herein may include some or all of the aforementioned benefits.

[0039] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

44025507W001What is claimed is:

1. An optical device, comprising:at least one grating over a surface of a substrate, wherein each grating comprises a plurality of structures;one or more gap fill materials over the plurality of structures;an encapsulation material over the one or more gap fill materials;a high-elongation material over the encapsulation material, the high-elongation material having an elongation greater than or equal to 20%; anda lens over the high-elongation material.

2. The optical device of claim 1 , wherein the lens is a 3D printed lens.

3. The optical device of claim 1, wherein the encapsulation material has a coefficient of thermal expansion less than or equal to 30 parts per million per Kelvin.

4. The optical device of claim 1, wherein the lens is formed of a lens material having a coefficient of thermal expansion greater than or equal to 40 parts per million per Kelvin.

5. The optical device of claim 1, wherein the high-elongation material comprises silicone, acrylate, epoxy, polyurethane, or a combination thereof.

6. The optical device of claim 1, wherein the one or more gap fill materials comprise a first gap fill material having a refractive index of about 1.1.

7. The optical device of claim 1, wherein the one or more gap fill materials comprise:a first gap fill material having a refractive index of about 1.1; anda second gap fill material having a refractive index of about 1.7.

8. An optical device, comprising:a waveguide comprising a substrate with at least one grating over a surface of the substrate;44025507W001a high-elongation material over the waveguide, the high-elongation material having an elongation greater than or equal to 20%; anda lens over the high-elongation material.

9. The optical device of claim 8, wherein the lens is a 3D printed lens.

10. The optical device of claim 8, wherein at least a portion of the waveguide has a coefficient of thermal expansion less than or equal to 30 parts per million per Kelvin.

11. The optical device of claim 8, wherein the lens is formed of a lens material having a coefficient of thermal expansion greater than or equal to 40 parts per million per Kelvin.

12. The optical device of claim 8, wherein the high-elongation material comprises silicone, acrylate, epoxy, polyurethane, or a combination thereof.

13. A method for forming an optical device, comprising:etching a plurality of structures into a grating material deposited over a substrate;depositing one or more gap fill materials over the structures;depositing an encapsulation material over the one or more gap fill materials; depositing a high-elongation material over the encapsulation material, the high-elongation material having an elongation greater than or equal to 20%; and depositing a lens over the high-elongation material.

14. The method of claim 13, further comprising performing a cooling operation on the optical device.

15. The method of claim 13, wherein depositing the lens comprises depositing an optical lens material at a deposition temperature using a 3D printing process, wherein the optical lens material has a coefficient of thermal expansion greater than or equal to 40 parts per million per Kelvin.44025507W00116. The method of claim 15, wherein the optical lens material comprises epoxy, polyacrylate, or combinations thereof.

17. The method of claim 13, wherein depositing a high-elongation material comprises depositing a liquid high-elongation material and solidifying the high-elongation material using a curing process.

18. The method of claim 13, wherein depositing a high-elongation material comprises:depositing an optically clear adhesive tape over the encapsulation material; depositing the high-elongation material over the optically clear adhesive tape; andperforming a lamination process.

19. The method of claim 13, wherein the encapsulation material has a coefficient of thermal expansion less than or equal to 30 parts per million per Kelvin.

20. The method of claim 13, wherein the high-elongation material comprises silicone, acrylate, epoxy, polyurethane, or a combination thereof.

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