An integrated ultra-light-thin ar display optical module, a preparation method and application thereof

Abstract

This invention provides an integrated ultra-thin AR display optical module, its fabrication method, and its applications. The integrated ultra-thin AR display optical module of this invention includes: an optical waveguide for total internal reflection propagation of light; a microdisplay for providing an image light source; a meta-lens integrated on the optical waveguide and located in the light-emitting path of the microdisplay, used to modulate the image light source provided by the microdisplay into coupled light suitable for total internal reflection propagation within the optical waveguide; and a coupling grating formed on the optical waveguide for coupling and emitting the light after total internal reflection propagation. The integrated ultra-thin AR display optical module of this invention has significant advantages such as significantly reduced volume, simplified optical system, increased design freedom, realization of binocular 3D display, reduced production cost, and significantly improved luminous efficiency.

Description

Technical Field

[0001] This invention relates to the field of AR technology, and in particular to an integrated ultra-thin AR display optical module, its fabrication method, and its application. Background Technology

[0002] Existing AR optical modules include an AR optical engine system and an optical waveguide. The AR optical engine system includes a microdisplay and a lens group. The microdisplay provides an image source, and the lens group is responsible for converting the light from the image source into collimated light and directing it into the coupling grating of the optical waveguide.

[0003] Currently, AR optical engine systems rely on traditional geometric optics for their lens assembly, requiring multiple lenses to form an optical system to achieve collimated light, thus significantly increasing the size of the AR optical engine system. When the AR optical engine is placed on AR glasses, noticeable protrusions appear on the temples or frames, severely affecting the appearance, size, volume, and weight of the AR glasses.

[0004] To reduce the impact of AR optical engine size on the overall size and appearance of AR glasses, a dual-mode AR waveguide was developed. This reduces the AR optical engine system, originally placed on both sides of the glasses, to a single unit placed in the center, allowing both eyes to share the same image source. However, this approach results in a protrusion in the center of the glasses, severely limiting the glasses' design and preventing the realization of binocular 3D visuals.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated ultra-thin AR display optical module, its preparation method and application, which has significant advantages such as significantly reduced volume, simplified optical system, increased design freedom, realization of binocular 3D display, reduced production cost and greatly improved light efficiency.

[0007] This invention provides an integrated ultra-thin AR display optical module, comprising: Optical waveguide: used for total internal reflection of light; Microdisplay: Used to provide a light source for images; Meta-lens: Integrated on the optical waveguide and located in the light output path of the micro-display, used to modulate the image light source provided by the micro-display into coupled light suitable for total internal reflection propagation within the optical waveguide; Coupling grating: Formed on an optical waveguide sheet, used to couple out light rays that have propagated through total internal reflection of the optical waveguide sheet.

[0008] Optical waveguide sheets are primarily used for total internal reflection of light. They can be made from high-refractive-index materials such as silicon carbide, gallium nitride, lithium niobate, and high-refractive-index glass. Utilizing their high refractive index, waveguides with a large field of view (FOV) can be fabricated. Furthermore, optical waveguide sheets can be single-layered or multi-layered, enabling monochrome and full-color displays.

[0009] Microdisplays are primarily used to provide image light sources and can employ various display technologies such as LCOS, Micro OLED, Micro LED, DLP, and LBS. Pixel-to-pixel optical fibers can also be used as the image source to further enhance display quality and reduce power consumption. Microdisplays can be laminated and integrated onto optical waveguide sheets.

[0010] Metalenses are primarily used to modulate the image light source provided by a microdisplay into coupled light suitable for total internal reflection propagation within an optical waveguide. The metalens is integrated onto the optical waveguide and located in the light-emitting path of the microdisplay. Multiple metalenses can be stacked together as needed. Replacing the lens assembly of traditional AR optical engine systems with metalenses, whose thickness is only at the micrometer level, allows for collimation and beam shaping functions similar to traditional multiple lenses within a micrometer-thickness, significantly reducing the thickness of traditional lens assemblies. Furthermore, the integrated design of the metalens and optical waveguide enables planarization and miniaturization of optical components, fundamentally solving the problem of excessive size in traditional AR optical engine systems.

[0011] The coupling grating is mainly used to couple out light rays that have propagated through total internal reflection in an optical waveguide sheet; the coupling grating is formed on the optical waveguide sheet. A metalens can be used instead of the coupling grating to resolve convergence interference. Alternatively, two-dimensional gratings, rectangular gratings, and rhombic gratings can also be used as coupling gratings, simultaneously providing pupil expansion and replacing extended gratings.

[0012] Furthermore, the integrated ultra-thin AR display optical module of the present invention also includes a coupling grating formed on the optical waveguide sheet, which is mainly used to guide the coupled light modulated by the metalens into the optical waveguide sheet.

[0013] Furthermore, the integrated ultra-thin AR display optical module of the present invention also includes an extended grating formed on the optical waveguide sheet. The extended grating is located between the input grating and the output grating and is used to expand the pupil of light in one or two dimensions.

[0014] Furthermore, at least one of the metalens, coupling grating, coupling grating, and extended grating is a metasurface grating, which is composed of a subwavelength periodic nanostructure array etched on an optical waveguide sheet; high refractive index materials such as TiO2 and SiN can be used as nanopillars for the metalens. In addition, conventional one-dimensional or two-dimensional gratings or geometric gratings can be used to completely replace metasurface gratings to achieve light coupling, coupling, and extension.

[0015] This invention also provides a method for fabricating the above-mentioned integrated ultra-thin AR display optical module, comprising the following steps: S1: Provides optical waveguide sheets; S2: A master copy containing metalenses and various grating patterns is created using photolithography. S3: The pattern on the master plate is transferred to the imprinting adhesive layer on the surface of the optical waveguide sheet using nanoimprint technology; S4: Using a patterned imprinted adhesive layer as a mask, the pattern is copied onto the optical waveguide sheet using an etching process.

[0016] In step S2, the photolithography technology can be EBL, DUV, EUV, LDWL, etc.

[0017] In step S4, etching processes such as RIE and ICP can be used; in addition, techniques such as ALD and PVD deposition can be used to precisely control the nanostructure of the metalens.

[0018] The present invention also provides an AR glasses, including an eyeglass frame and the aforementioned integrated ultra-thin AR display optical module, wherein the integrated ultra-thin AR display optical module is integrated on the eyeglass frame.

[0019] The implementation of this invention has at least the following advantages: 1. Significantly reduced volume: The thickness of the meta-lens can be controlled at the micrometer level (while the traditional lens group of AR optical engine system is at the millimeter level), which reduces the volume of AR optical engine system by more than 99% and completely eliminates the protruding parts of AR glasses.

[0020] 2. Reduced production costs: By eliminating the processing and assembly costs of multiple precision lenses in traditional optical systems, the total cost of AR optical modules is expected to be reduced by 15-20%.

[0021] 3. Increased design freedom: Eliminating size limitations allows AR glasses to be designed to look like ordinary glasses, greatly increasing user acceptance.

[0022] 4. Achieve binocular 3D display: Due to the significant reduction in size, independent optical engine systems can be configured for each eye, achieving a true binocular 3D display effect and solving the visual 3D experience problem of existing one-to-two AR waveguides.

[0023] 5. Material advantages: Silicon carbide has high refractive index, high thermal stability and mechanical strength, which improves the optical performance and durability of optical waveguide sheets.

[0024] 6. Simplified optical system: Metalenses can realize the functions of lens groups in traditional AR optical engine systems, reducing the number of optical components and lowering assembly complexity and optical alignment difficulty.

[0025] 7. Improved light efficiency: The special nanostructure of metalenses can reduce light reflection and absorption losses, improving the overall light efficiency of the optical system by 5-10%.

[0026] 8. Solving the problem of infinity focal plane in traditional AR waveguide imaging: By using metalenses, imaging with adjustable focal plane distance can be achieved, thus solving the convergence adjustment conflict. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of the first integrated ultra-thin AR display optical module. Figure 2 This is a schematic diagram of the structure of the second type of integrated ultra-thin AR display optical module; Figure 3 This is a schematic diagram of the structure of the third type of integrated ultra-thin AR display optical module; Figure 4 This is a schematic diagram of the structure of the fourth type of integrated ultra-thin AR display optical module; Figure 5 This is a schematic diagram of the structure of the fifth type of integrated ultra-thin AR display optical module; Figure 6 A top view of the integrated ultra-thin AR display optical module.

[0029] Explanation of reference numerals in the attached figures: 1: Optical waveguide; 2: Microdisplay; 3: Metalens; 4: Coupling grating; 5: Insertion grating; 6: Extended grating. Detailed Implementation

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1 Combination Figures 1 to 6 As shown, the integrated ultra-thin AR display optical module of this embodiment includes an optical waveguide 1, a microdisplay 2, a meta-lens 3, and a coupling grating 4.

[0034] The optical waveguide 1 is mainly used for total internal reflection of light. Its material can be a high-refractive-index material, such as silicon carbide, gallium nitride, lithium niobate, or high-refractive-index glass. Utilizing its high refractive index, waveguides with a large field of view (FOV) can be fabricated. Furthermore, the optical waveguide 1 can employ single-layer or multi-layer waveguides, thereby enabling monochrome and full-color displays.

[0035] The microdisplay 2 is mainly used to provide an image light source. It can be an LCOS, Micro OLED, Micro LED, DLP, LBS, or other display screens. Pixel-to-pixel optical fibers can also be used as the image source to further improve the display effect and reduce power consumption. The microdisplay 2 can be laminated and integrated onto the optical waveguide 1.

[0036] The meta-lens 3 is mainly used to modulate the image light source provided by the microdisplay 2 into coupled light suitable for total internal reflection propagation within the optical waveguide 1. The meta-lens 3 is integrated on the optical waveguide 1 and located in the light output path of the microdisplay 2. Multiple meta-lenses 3 can be stacked together for use as needed. Replacing the lens group of the traditional AR optical engine system with the meta-lens 3, the thickness of the meta-lens 3 is only at the micrometer level, which can achieve the collimation and beam shaping functions of traditional multiple lenses within a micrometer thickness, greatly reducing the thickness of the traditional lens group. At the same time, the integrated design of the meta-lens 3 and the optical waveguide 1 realizes the planarization and miniaturization of optical components, fundamentally solving the problem of excessive size in traditional AR optical engine systems.

[0037] The coupling grating 4 is mainly used to couple out light rays that have propagated through total internal reflection of the optical waveguide 1; the coupling grating 4 is formed on the optical waveguide 1. In addition, two-dimensional gratings, rectangular gratings, rhomboid gratings, etc. can also be used as coupling grating 4, and at the same time have the function of expanding pupil, which can replace the expansion grating.

[0038] like Figure 1 As shown, the microdisplay 2 and the meta-lens 3 are integrated at the first end of the first side of the optical waveguide 1. The meta-lens 3 is located between the microdisplay 2 and the optical waveguide 1. The coupling grating 4 is integrated at the other end (second end) of the first side of the optical waveguide 1. The image light source emitted by the microdisplay 2 is first modulated by the meta-lens 3 into coupled light suitable for total internal reflection propagation in the optical waveguide 1, and then directly transmitted to the coupling grating 4 through the optical waveguide 1, and finally an image is formed in the human eye.

[0039] Furthermore, the integrated ultra-thin AR display optical module of this embodiment may also include a coupling grating 5 formed on the optical waveguide 1. The coupling grating 5 is mainly used to guide the coupled light modulated by the metalens 3 into the optical waveguide 1. Figure 2 As shown, a coupling grating 5 is integrated at the first end of the second side of the optical waveguide 1. At this time, the coupled light modulated by the meta-lens 3 first enters the coupling grating 5 through the optical waveguide 1, then passes through the optical waveguide 1 to the coupling grating 4, and finally forms an image in the human eye.

[0040] As a derived structure, such as Figure 3 As shown, the meta-lens 3 and the coupling grating 5 can also be integrated at the first end of the first side of the optical waveguide 1, with the coupling grating 5 located between the meta-lens 3 and the optical waveguide 1, while the output grating 4 is integrated at the other end of the first side of the optical waveguide 1. Figure 4 As shown, the meta-lens 3 and the coupling grating 4 can also be integrated at the first end and the second end of the first side of the optical waveguide 1, respectively. Figure 5 As shown, the meta-lens 3 can also be integrated on the first end of the first side of the optical waveguide 1, and the coupling grating 4 can be integrated on the second end of the second side of the optical waveguide 1.

[0041] Furthermore, such as Figure 6 As shown, the integrated ultra-thin AR display optical module of this embodiment may also include an extended grating 6 formed on the optical waveguide 1. The extended grating 6 is located between the coupling grating 5 and the coupling grating 4 and is used to expand the pupil of light in one or two dimensions.

[0042] In this embodiment, at least one of the metalens 3, the coupling grating 5, the coupling grating 4, and the expansion grating 6 is a metasurface grating, which is composed of a subwavelength periodic nanostructure array etched on the optical waveguide 1; high refractive index materials such as TiO2 and SiN can be used as the nanopillars of the metalens 3. Furthermore, conventional one-dimensional or two-dimensional gratings or geometric gratings can be used to completely replace the metasurface grating to achieve light coupling, coupling, and expansion.

[0043] The thickness of the meta-lens 3 in the integrated ultra-thin AR display optical module of this embodiment can be controlled at the micrometer level, reducing the volume of the AR optomechanical system by more than 99%, completely eliminating the protruding parts of the AR glasses, and significantly reducing the size. Since the processing and assembly costs of multiple precision lenses in traditional optical systems are eliminated, the total cost of the AR optical module can be reduced by 15-20%, greatly reducing production costs. At the same time, since the volume limitation is eliminated, the AR glasses can be designed with the appearance of ordinary glasses, greatly improving user acceptance and design freedom. Due to the significant reduction in size, independent optomechanical systems can be configured for the left and right eyes respectively, realizing a true binocular 3D display effect. In addition, the special nanostructure of the meta-lens 3 can reduce light reflection and absorption loss, improve the overall light efficiency of the optical system by 5-10%, and the meta-lens 3 can be used to achieve imaging with adjustable focal plane distance, thereby solving the convergence conflict.

[0044] Example 2 This embodiment provides a method for fabricating the integrated ultra-thin AR display optical module of Embodiment 1, including the following steps: S1: Provides optical waveguide sheets High-refractive-index materials such as silicon carbide, gallium nitride, lithium niobate, and high-refractive-index glass are selected as the materials for the optical waveguide sheet 1 and cleaned. Utilizing their high refractive index characteristics, waveguides with a large field of view (FOV) can be fabricated. Furthermore, single-layer or multi-layer waveguides can be used to achieve monochrome and full-color displays.

[0045] S2: Creating the Master Plate A master copy containing a metalens 3 and patterns of various gratings (outgoing grating 4, incoming grating 5, and extended grating 6) is produced using photolithography techniques such as EBL, DUV, EUV, and LDWL.

[0046] S3: Pattern Transfer A layer of UV-curable nanoimprint adhesive is uniformly coated on the surface of the optical waveguide sheet 1, and the pattern on the master plate is transferred to the imprint adhesive layer on the surface of the optical waveguide sheet 1 using nanoimprint technology.

[0047] S4: Etching Using a patterned imprinted adhesive layer as a mask, the pattern is permanently copied onto the optical waveguide sheet 1 using etching processes such as RIE and ICP, and then the residual imprinted adhesive mask is removed. In addition, the nanostructure of the metalens 3 can be precisely controlled using techniques such as ALD and PVD deposition.

[0048] Finally, the microdisplay 2 is aligned and fixed with the prepared module with high precision to obtain an integrated ultra-thin AR display optical module.

[0049] The fabrication method of this embodiment integrates the meta-lens 3 with the optical waveguide 1 into a single design, realizing the planarization and miniaturization of optical elements and fundamentally solving the problem of excessive size in traditional AR optomechanical systems. At the same time, based on nanoimprinting and etching micro-nano fabrication processes, the high-precision replication and large-scale production feasibility of the meta-lens 3 and the grating structure are ensured. In addition, the optical design of the meta-lens 3 enables it to achieve the collimation and beam shaping functions of traditional multiple lenses within a micrometer-level thickness, and the special nanostructure can reduce light reflection and absorption losses, thereby improving the overall light efficiency of the optical system by 5-10%.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integrated ultra-thin AR display optical module, characterized in that, include: Optical waveguide: used for total internal reflection of light; Microdisplay: Used to provide a light source for images; Meta-lens: Integrated on the optical waveguide and located in the light output path of the micro-display, used to modulate the image light source provided by the micro-display into coupled light suitable for total internal reflection propagation within the optical waveguide; Coupling grating: Formed on an optical waveguide sheet, used to couple out light rays that have propagated through total internal reflection of the optical waveguide sheet.

2. The integrated ultra-thin AR display optical module according to claim 1, characterized in that, It also includes a coupling grating formed on the optical waveguide sheet, used to guide the coupled light modulated by the metalens into the optical waveguide sheet.

3. The integrated ultra-thin AR display optical module according to claim 1, characterized in that, It also includes an extended grating formed on the optical waveguide sheet, which is located between the input grating and the output grating and is used to expand the pupil of light in one or two dimensions.

4. The integrated ultra-thin AR display optical module according to any one of claims 1-3, characterized in that, At least one of the metalens, coupling grating, coupling grating and extended grating is a metasurface grating, which is composed of a subwavelength periodic nanostructure array etched on an optical waveguide sheet.

5. The integrated ultra-thin AR display optical module according to claim 1, characterized in that, The material of the optical waveguide is a high refractive index material, which is selected from silicon carbide, gallium nitride, lithium niobate, and high-refractive glass.

6. The integrated ultra-thin AR display optical module according to claim 1, characterized in that, Microdisplays can be OLED, LED, LCOS, DLP, or LBS displays.

7. The method for fabricating the integrated ultra-thin AR display optical module according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Provides optical waveguide sheets; S2: A master copy containing metalenses and various grating patterns is created using photolithography. S3: The pattern on the master plate is transferred to the imprinting adhesive layer on the surface of the optical waveguide sheet using nanoimprint technology; S4: Using a patterned imprinted adhesive layer as a mask, the pattern is copied onto the optical waveguide sheet using an etching process.

8. The preparation method according to claim 7, characterized in that, The photolithography technique is selected from one of EBL, DUV, EUV, and LDWL.

9. The preparation method according to claim 7, characterized in that, The etching process is selected from RIE or ICP.

10. An AR glasses, characterized in that, The invention includes an eyeglass frame and an integrated ultra-thin AR display optical module as described in any one of claims 1-6, wherein the integrated ultra-thin AR display optical module is integrated onto the eyeglass frame.

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