Diffractive Optical Structure and Near-Eye Display Device

Abstract

Embodiments of the present application disclose a diffractive optical structure and a near-eye display device; the diffractive optical structure comprises a substrate and a coupling-in region and a coupling-out region installed on the substrate; the coupling-out region comprises a grating structure, wherein the grating structure comprises a plurality of periodically arranged grating ridges and grating grooves between adjacent grating ridges, and the grating grooves are made of at least two materials with different refractive indices; the average refractive index of the different materials within a grating unit period of the grating structure is , where 1.1 < ≤ 2.4, and where V1 to Vm are each volumes or areas from the first material to the m-th material, n1 to nm are each refractive indices from the first material to the m-th material, and Vunitcell is the volume or area of ​​the grating unit period.

Description

Technology Field

[0001] This application belongs to the field of augmented reality (AR) technology, and specifically, this application relates to a diffractive optical structure and a near-eye display device. Background Technology

[0002] With the rapid advancement of Augmented Reality (AR) technology, diffractive waveguide-based AR optical solutions are establishing themselves as a key method for realizing efficient and lightweight display systems. In this field, the overall optical efficiency of the waveguide is one of the important indicators for evaluating performance superiority. In prior art, the ability to tune and control diffraction efficiency in the non-coupling-in region is a major factor limiting further improvement in waveguide efficiency.

[0003] Therefore, effectively improving the ability to tune and control diffraction efficiency in the non-coupling-in region and implementing tuning and control for the flexible shift of the grating's diffraction efficiency curve has become an urgent problem that needs to be solved in current AR optical solutions.

[0004] The purpose of the present application is to provide a new technical solution for diffractive optical structures and near-eye display devices.

[0005] According to a first aspect of the present application, an embodiment of the present application provides a diffractive optical structure, wherein the diffractive optical structure comprises a substrate and a coupling-in region and a coupling-out region installed on the substrate;

[0006] The coupling-out region comprises a lattice structure, wherein the lattice structure comprises a plurality of periodically arranged lattice ridges and lattice grooves between adjacent lattice ridges, and the lattice grooves are made of at least two materials with different refractive indices;

[0007] The average refractive index of different materials within the lattice unit period of the above lattice structure is and, 1.1< ≤2.4, and, here, V 1~ V m Each one 1 From the materials m It is the volume or area up to the material, and n 1~ n m Each one 1 From the materials m It is the refractive index up to the material, and V unitcell is the volume or area of ​​a lattice unit period.

[0008] Optionally, the average refractive index of different materials within the lattice unit period of the lattice structure is 1.35≤ ≤2.15.

[0009] Optionally, the substrate comprises two opposing surfaces, and the coupling-in region and the coupling-out region are installed on at least one surface of the substrate;

[0010] The coupling-in region couples an external light beam into the substrate;

[0011] The above coupling-out region couples out the light by dilating the pupil.

[0012] Optionally, the grid structure has a first period along a first direction P It includes a plurality of grid ridges arranged according to 1, wherein a grid groove is located between any two adjacent grid ridges, and at least a portion of the grid groove is an air groove;

[0013] Average refractive index of different materials within the lattice unit period of the above lattice structure It is as follows,

[0014] ;

[0015] Here, = + +… … + is the longitudinal cross-sectional area of ​​the above grid ridge, and is the refractive index of the above-mentioned grating ridge, and is the longitudinal cross-sectional area of ​​the above air groove, and is the refractive index of air, and The one filled within the above grid groove 1 It is the longitudinal cross-sectional area of ​​the filler, and The one filled within the above grid groove 1 It is the refractive index of the filler, and The one filled within the above grid groove m It is the longitudinal cross-sectional area of ​​the filler, and The one filled within the above grid groove m It is the refractive index of the filler; = P 1* H , H is the height of the grid ridge mentioned above.

[0016] Optionally, the grid structure comprises a plurality of grid ridges, and the plurality of grid ridges have a second period along a second direction P At intervals of 2, and along the third direction, the third period P Arranged at intervals of 3, a grid groove is located between any two adjacent grid ridges, and at least a portion of the grid groove is an air groove;

[0017] Average refractive index of different materials within the lattice unit period of the above lattice structure It is as follows,

[0018] ;

[0019] = + +… … + is the volume of the above lattice ridge, and is the refractive index of the above-mentioned grating ridge, and is the volume of the above air groove, and is the refractive index of air, and The one filled within the above grid groove 1 It is the volume of the filler, and The one filled within the above grid groove 1It is the refractive index of the filler, and The one filled within the above grid groove m It is the volume of the filler, and The one filled within the above grid groove m It is the refractive index of the filler; =( P 2* P 3)* H , H is the height of the grid ridge mentioned above.

[0020] Optionally, the grid structure is coated with at least one layer of filler, and the refractive index of the filler and the refractive index of the grid ridge are different.

[0021] Optionally, the at least one layer of filler is 1 Includes a filler, and the above 1 The filler is coated on the surface of the grid ridge and the groove walls and bottom of the grid groove, and the grid groove is an air groove and the 1 It includes filler material.

[0022] Optionally, the at least one layer of filler is 2 It further includes a filler, and the above 2 The filler is the above-mentioned 1 It is coated on the filler, and the grid groove is the above 2 It further includes a filler while maintaining an air groove, and the above 1 Filler and the above 2 The refractive indices of the filler materials are different.

[0023] Optionally, the at least one layer of filler is 3 It further includes a filler, and the above 3 The filler is the above-mentioned 1 The above-mentioned moving away from the filler 2 It is coated on the surface of the filler, and within the grid groove, the 3 Further including a filler material, and the above 3 The filler is filled into the above air groove;

[0024] The above1 Filler material, the above 2 Filler material and the above 3 The refractive indices of the fillers are different from each other.

[0025] According to a second aspect of the present application, an embodiment of the present application provides a near-eye display device, and said near-eye display device,

[0026] Image source; and

[0027] A diffraction optical structure according to the first aspect is included, and a light ray emitted from the image source can be incident on the coupling-in region of the diffraction optical structure.

[0028] The beneficial effects of the embodiments of the present application are as follows.

[0029] The diffractive optical structure provided in the embodiments of the present application is the average refractive index of different materials within a lattice unit period of the lattice structure in the coupling-out region (i.e., the uncoupling-in region). By adjusting and controlling the range, adjustment and control of the precise shift of the diffraction efficiency curve of the grating structure are achieved, and this design can significantly improve the overall coupling-out efficiency of the diffractive optical structure. Specifically, as a light ray undergoes total internal reflection along the interior of the substrate and is gradually transmitted to the rear end, the reflection angle of the light ray naturally decreases. This application, through a sophisticated design, [possesses] the average refractive index value of different materials within a grating unit period of the grating structure within the coupling-out region. By reducing it in a timely manner, it is ensured that the peak of the coupling-out efficiency curve can be flexibly shifted in the small angle direction, thereby accurately meeting the coupling-out requirements of small angle rays.

[0030] The technical solution provided in the embodiment of the present application not only overcomes the difficulty of precisely adjusting and controlling the shape and peak position of the coupling-out efficiency curve at different locations present in existing methods, but also accurately positions the peak of the coupling-out efficiency curve at the position of the minimum reflection angle of the light ray, thereby significantly optimizing the transmission path of the light ray and the coupling-out efficiency within the diffractive optical structure.

[0031] Other features and advantages of the present application will become clear from the following detailed description of exemplary embodiments of the present application with reference to the drawings. Brief explanation of the drawing

[0032] Drawings incorporated into the specification and constituting part of the specification are used to illustrate embodiments of the present application and to explain the principles of the present application together with the description. FIG. 1 is a schematic diagram of the structure of a diffraction optical structure provided in an embodiment of the present application. FIG. 2 is a schematic diagram 1 of the lattice structure of the coupling-out region provided in an embodiment of the present application. FIG. 3 is the coupling-out efficiency curve 1 of the diffraction optical structure provided in an embodiment of the present application. FIG. 4 is the coupling-out efficiency curve 2 of the diffraction optical structure provided in an embodiment of the present application. FIG. 5 is the coupling-out efficiency curve 3 of the diffraction optical structure provided in an embodiment of the present application. FIG. 6 is a schematic diagram 2 of the lattice structure of the coupling-out region provided in an embodiment of the present application. FIG. 7 is the coupling-out efficiency curve 4 of the diffraction optical structure provided in an embodiment of the present application. FIG. 8 is a schematic diagram 3 of the lattice structure of the coupling-out region provided in an embodiment of the present application. FIG. 9 is a schematic diagram 4 of the lattice structure of the coupling-out region provided in an embodiment of the present application. FIG. 10 is a schematic diagram 5 of the lattice structure of the coupling-out region provided in an embodiment of the present application. FIG. 11 is a schematic diagram 6 of the lattice structure of the coupling-out region provided in an embodiment of the present application. FIG. 12 is a schematic diagram 7 of the lattice structure of the coupling-out region provided in an embodiment of the present application. FIG. 13 is a schematic diagram 8 of the lattice structure of the coupling-out region provided in an embodiment of the present application. Specific details for implementing the invention

[0033] Various exemplary embodiments of the present application are described below with reference to the drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions, and numerical values ​​described in these embodiments do not limit the scope of the present application.

[0034] The following description of at least one exemplary embodiment is substantially for illustrative purposes only and is not intended to limit the present application or its application or use.

[0035] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification.

[0036] In all examples presented and discussed herein, any specific value should be interpreted merely as exemplary and not restrictive. Accordingly, other examples of exemplary embodiments may have different values.

[0037] It should be noted that since similar reference numerals in the attached drawings indicate similar components, if a component is defined in one drawing, there is no need to discuss that component further in subsequent drawings.

[0038] Below, the diffraction optical structure and near-eye display device provided in the embodiments of the present application are described in detail together with the drawings.

[0039] In diffractive optical structures, the diffractive waveguide is a common form, and hereinafter, the diffractive waveguide is abbreviated as the waveguide.

[0040] The overall optical efficiency of an optical waveguide consists primarily of two parts: coupling-in efficiency and pupil dilation coupling-out efficiency. While coupling-in efficiency focuses mainly on efficiently coupling external light rays into the optical waveguide, pupil dilation coupling-out efficiency is more complex, requiring precise coupling-out adjustment and control for light rays at different angles at different locations. Unlike the principle of seeking the highest possible coupling-in efficiency, pupil dilation coupling-out efficiency must effectively couple out light rays at different angles at different locations according to actual demand. For example, since light rays with short transmission paths and large total reflection angles are dominant at the front end of the coupling-out region, the peak of the coupling-out efficiency curve in that region is typically located at a large angle. However, as the light rays are transmitted to the rear end of the optical waveguide, the transmission path increases and the total reflection angle gradually decreases; therefore, the coupling-out efficiency curve must be able to correspondingly adjust the peak position to meet the coupling-out requirements of small-angle light rays. However, existing methods for adjusting and controlling pupil dilation coupling-out have faced many difficulties in implementing such adjustment and control, making it difficult to precisely control the shape of the coupling-out efficiency curve and the peak position at different locations. To address this, the present application provides a novel diffractive optical structure design, which is described in detail below.

[0041] According to one embodiment of the present application, a diffractive optical structure is provided, and with reference to FIG. 1, the diffractive optical structure comprises a substrate (3) and a coupling-in region (1) and a coupling-out region (2) installed on the substrate (3), wherein the coupling-out region (2) comprises a grating structure, wherein the grating structure comprises a plurality of periodically arranged grating ridges (201) and grating grooves (202) between adjacent grating ridges (201), and the grating grooves (202) are made of at least two materials with different refractive indices; and the average refractive index of the different materials within a grating unit period of the grating structure is and, 1.1< ≤2.4, and, here, V 1~ V m Each one 1 From the materials m It is the volume or area up to the material, and n 1~ n m Each one 1 From the materials m It is the refractive index up to the material, and V unitcell is the volume or area of ​​a lattice unit period.

[0042] In the design of a diffractive optical structure provided in an embodiment of the present application, with reference to FIG. 1, the diffractive optical structure comprises a substrate (3) and a coupling-in region (1) and a coupling-out region (2) installed thereon, and the design of the present application is the average refractive index value of different materials within a grid unit period of a grid structure installed within the coupling-out region (2). Efficient ray coupling-out is achieved by adjusting and controlling it. For example, 1.1< ≤2.4.

[0043] The diffraction optical structure provided in the embodiment of the present application includes the following parts, which are described in detail below.

[0044] Substrate (3): As a basic support layer of the entire diffractive optical structure, it provides a stable platform for the coupling-in region (1) and the coupling-out region (2). The substrate (3) must have good optical transparency and mechanical stability to ensure efficient transmission of light rays and stability of the entire structure.

[0045] Coupling-in region (1): The main function of this region is to effectively couple-in external light rays into the substrate (3), which corresponds to the entrance where the light rays enter the diffraction optical structure.

[0046] Coupling-out region (2): This region includes a specially designed grating structure for coupling-out the light beam into external space by expanding the pupil (i.e., expanding the beam diameter) within the diffractive optical structure, and in this application, this region is a key part for realizing efficient light utilization.

[0047] In the diffractive optical structure provided in an embodiment of the present application, with reference to FIGS. 1 and 2, the coupling-out region (2) comprises a specially designed grating structure, wherein the grating structure is composed of a plurality of periodically arranged grating ridges (201) and grating grooves (202) between adjacent grating ridges; wherein the average refractive index of different materials within a grating unit period of the grating structure Design (e.g., 1.1< By designing it to ≤2.4, it is possible to influence the diffraction efficiency curve of the above grating structure and achieve efficient light coupling-out.

[0048] Here, the grid groove (202) may be filled with at least two materials, such as air and at least one low-refractive-index material. When the grid groove (202) is entirely filled with air, the average refractive index of the different materials within the grid unit period of the grid structure It is 1.1.

[0049] Average refractive index of the lattice structure To adjust and control, the present application provides various methods, and with reference to FIGS. 2 and FIGS. 6, includes a method of introducing air and / or other low-refractive-index material into the grid groove (202).

[0050] For example, various processes such as spin coating adhesive filling, inkjet adhesive filling, ALD deposition, PVD deposition, and CVD deposition can be used. By using these methods alone or in combination, the average refractive index value of the lattice structure at different locations By adjusting it, the coupling-out requirements for different angle rays can be met, thereby improving the coupling-out efficiency and ray uniformity of the entire optical diffraction structure.

[0051] According to the diffractive optical structure provided in the embodiment of the present application, the key lies in the special design of the grating structure within the coupling-out region (2), and the average refractive index of different materials within the grating unit period is set within the range of 1.1 to 2.4 mentioned in the above embodiments. This design utilizes the ability to adjust the physical parameters of the lattice structure to obtain the average refractive index value of different materials within a lattice unit period. It is to control it precisely.

[0052] Specifically, by adjusting the size (e.g., area or volume) and refractive index of the grid ridge (201) and grid groove (202) and introducing air or other low-refractive-index material, the average refractive index value of different materials within a grid unit period of the grid structure This design can be flexibly changed. This design not only expands the adjustment and control range, but also optimizes the coupling-out efficiency and uniformity of light rays by flexibly adjusting the shape and position of the grating's diffraction efficiency curve as needed.

[0053] The diffractive optical structure designed in this way not only improves the utilization efficiency of light rays but also enhances the overall performance of the diffractive optical structure, thereby providing a clearer and more uniform visual experience to near-eye display devices.

[0054] The diffraction optical structure provided in the embodiment of the present application can bring about at least the following technical effects by newly designing the grating structure of the coupling-out region (2) above it.

[0055] First, the average refractive index of different materials within the lattice unit period of the lattice structure in the coupling-out region (2). 1.1< By optimizing to ≤2.4, the diffractive optical structure provided in the embodiment of the present application can significantly improve the coupling-out efficiency of the light beam. This is because, as the reflection angle of the light beam naturally decreases during the process in which the light beam is coupled-in from the coupling-in region (1) into the substrate (3) and transmitted to the coupling-out region (2) (i.e., the rear end), This is because appropriately reducing the value of ensures that the peak of the coupling-out efficiency curve shifts toward the small angle direction, thereby satisfying the requirements for efficient coupling-out of different angle rays at different locations.

[0056] Second, the average refractive index of different materials within the grid unit period of the grid structure within the entire coupling-out region (2). By rationally adjusting and controlling it, the diffractive optical structure of the present application can improve the uniformity of light distribution and reduce light loss or distortion caused by non-uniform grating structures.

[0057] As can be seen from this, the diffraction optical structure provided in the embodiment of the present application significantly improves the optical performance of the entire diffraction optical structure by designing new optical parameters for the grating structure within the coupling-out region (2), thereby not only improving coupling-out efficiency but also enhancing the uniformity of the light rays.

[0058] The diffractive optical structure provided in the embodiments of the present application is the average refractive index of different materials within a lattice unit period of the lattice structure in the coupling-out region (uncoupling-in region). By adjusting and controlling, adjustment and control of the precise shift of the diffraction efficiency curve of the grating structure are achieved, and the design can improve the overall coupling-out efficiency of the optical structure. Specifically, as a light ray undergoes total internal reflection along the interior of the substrate and is gradually transmitted to the rear end, the reflection angle of the light ray naturally decreases. This application relates to the average refractive index value of different materials within a grating unit period of the grating structure within the coupling-out region through a sophisticated design. By reducing it in a timely manner, it is ensured that the peak of the coupling-out efficiency curve can be flexibly shifted in the small angle direction, thereby accurately meeting the coupling-out requirements of small angle rays.

[0059] The technical solution provided in the embodiment of the present application not only overcomes the difficulty of precisely adjusting and controlling the shape and peak position of the coupling-out efficiency curve at different locations present in existing methods, but also accurately positions the peak of the coupling-out efficiency curve at the position of the minimum reflection angle of the light ray, thereby significantly optimizing the transmission path of the light ray and the coupling-out efficiency within the diffractive optical structure.

[0060] In some examples of the present application, the average refractive index of different materials within a lattice unit period of the lattice structure 1.35< ≤2.15.

[0061] In this example of the present application, within the coupling-out region (2), the average refractive index of different materials within the grid unit period of the grid structure is 1.35≤ It is limited to ≤2.15. The design of this range is based on, on the one hand, adjusting using a low refractive index material based on the lattice ridge (201), and on the other hand, considering the optimization of the optical performance of the lattice structure.

[0062] Specifically, the average refractive index of different materials within the lattice unit period of the above lattice structure It is designed within the range of 1.35 to 2.15 (including the two endpoint values ​​of 1.35 and 2.15), which is the average refractive index value when designing the grid structure It means that it can be adjusted and controlled more precisely. The average refractive index value within this range By more effectively satisfying the transmission characteristics and coupling-out requirements of the light beam, efficient coupling-out of the light beam can be ensured at both different positions and angles.

[0063] By adjusting physical parameters of the grating structure, such as the size of the grating ridge (201) and grating groove (202) and the refractive index of the filler, within the range provided in this example of the present application, the shape and peak position of the diffraction efficiency curve of the grating can be controlled more precisely. In particular, the coupling-out efficiency can be significantly improved by ensuring that the peak of the coupling-out efficiency curve reaches an optimal position at different angles during the process of the light beam being transmitted from the coupling-in region (1) to the rear end.

[0064] The range provided in this example of the present application not only helps to improve coupling-out efficiency, but can also improve the uniformity of light distribution and reduce light loss. Average refractive index of different materials within a lattice unit period of the lattice structure within the coupling-out region (2) Since this is adjusted and controlled more precisely, the transmission path of the light beam within the substrate (3) of the diffractive optical structure becomes more stable, and light scattering and reflection caused by changes in the refractive index are reduced. This not only improves the utilization rate of the light beam but also makes the optical performance of the diffractive optical structure more stable and reliable.

[0065] In some examples of the present application, referring to FIG. 1, the substrate (3) comprises two opposing surfaces, and the coupling-in region (1) and the coupling-out region (2) are installed on at least one surface of the substrate (3); the coupling-in region (1) couples in an external light beam into the substrate (3); and the coupling-out region (2) couples out a light beam by dilating the pupil.

[0066] In one specific example, referring to FIG. 1, the coupling-in region (1) and the coupling-out region (2) are installed together on one of two opposing surfaces of the substrate (3), and the coupling-in region (1) and the coupling-out region (2) are installed adjacent to each other and spaced apart; within the coupling-out region (2), the lattice structure is the average refractive index value of different materials within a lattice unit period along the direction away from the coupling-in region (1). For example, this is installed to show a tendency to gradually decrease.

[0067] The specific analysis of the design in the above specific example is as follows.

[0068] (1) Efficient transmission in the initial stage:

[0069] In the case of a grid structure installed within the coupling-out region (2), the grid structure close to the coupling-in region (1) has a high average refractive index value It can be configured to have. This design takes into account the optical characteristics and requirements when a light ray just enters a diffractive optical structure. High average refractive index value This helps to enhance stability and transmission efficiency when the light beam enters the initial stage, thereby ensuring that the light beam can smoothly enter the substrate (3) from the coupling-in region (1) and propagate along a predetermined path.

[0070] (2) Within the coupling-out area (2), different positions of coupling-out requirements are met:

[0071] As the light beam is transmitted to the rear end within the substrate (3), the reflection angle gradually decreases. To optimize coupling-out efficiency, the grating structure within the coupling-out region (2) has an average refractive index value By designing it to gradually decrease, more precise and efficient ray coupling-out can be achieved at different positions and angles. In particular, at positions moving away from the coupling-in region (1), a low average refractive index value It ensures that the light beam can achieve efficient coupling-out even at small reflection angles.

[0072] (3) Effective optimization of light transmission and coupling-out efficiency:

[0073] The average refractive index of the grid structure within the entire coupling-out region (2) The gradient change design not only improves the transmission stability of light rays within the diffractive optical structure but also significantly optimizes the overall coupling-out efficiency. By precisely controlling the physical parameters and refractive index distribution of the grating structure, the diffractive optical structure of the present application enables precise adjustment and control of the light ray transmission path and coupling-out angle, thereby allowing the light rays to maintain high transmission efficiency and coupling-out efficiency throughout the entire length range of the substrate (3).

[0074] In summary, within the coupling-out region (2), the average refractive index of the lattice structure close to the coupling-in region (1) is set to a high value to ensure that the light beam can be transmitted efficiently and stably in the initial stage. The average refractive index of the grating structure as it moves further away from the coupling-in region (1) It gradually decreases to meet the coupling-out requirements of beams at different locations and optimizes overall beam transmission and coupling-out efficiency.

[0075] In some examples of the present application, referring to FIGS. 2 and FIGS. 6, the lattice structure has a first period along a first direction. P It includes a plurality of grid ridges (201) arranged according to 1, and a grid groove (202) is located between any two adjacent grid ridges (201), wherein at least a portion of the grid groove (202) is an air groove (203);

[0076] Average refractive index of different materials within the lattice unit period of the above lattice structure It is as follows,

[0077] ;

[0078] Here, = + +… … + is the longitudinal cross-sectional area of ​​the grid ridge (201), and is the refractive index of the above-mentioned grid ridge (201), and is the longitudinal cross-sectional area of ​​the air groove (203), and is the refractive index of air, and The silver filled within the grid groove (202) 1 It is the longitudinal cross-sectional area of ​​the filler, and The silver filled within the grid groove (202) 1 It is the refractive index of the filler, and The silver filled within the grid groove (202) m It is the longitudinal cross-sectional area of ​​the filler, and The silver filled within the grid groove (202) m It is the refractive index of the filler; =P 1* H , H is the height of the grid ridge (201) above.

[0079] The lattice structure provided in this example of the present application has a first period in only one direction. P It is a one-dimensional lattice containing 1.

[0080] In this example of the present application, the design of the grid structure involves filling at least one filler material and introducing air grooves (203) to obtain the average refractive index value of different materials within the grid unit period of the grid structure. The purpose is to adjust and control it.

[0081] As a light ray is transmitted within an optical waveguide, the reflection angle gradually changes. The grating structure design of the present application, depending on the specific location and angle of light transmission, the average refractive index of different materials within a grating unit period of the grating structure (In the text, sometimes the direct average refractive index value By adjusting (also abbreviated as), the peak of the grating's diffraction efficiency curve is shifted to an optimal position, thereby realizing efficient light coupling-out.

[0082] Average refractive index of the lattice structure By precisely controlling the distribution, the transmission path of light rays within the optical waveguide becomes more stable, improving light utilization and distribution uniformity while simultaneously reducing light loss.

[0083] Overall, the grating structure design provided in this application not only improves light coupling-out efficiency but also enhances the optical stability of the diffractive optical structure. This provides a clearer and more uniform visual experience for near-eye display devices, such as augmented reality, thereby meeting the complex and constantly changing requirements for light transmission and coupling-out.

[0084] In one specific example, referring to FIG. 2, when the cross-sectional views of the grid ridge (201) and the grid groove (202) are both rectangular and the grid groove (202) is an air groove (203), the average refractive index value of different materials within the grid unit period of the grid structure silver =(K1*n1+K2*n2) / P 1, where K1 is the width of the grid ridge (201), n1 is the refractive index of the grid ridge (201), K2 is the width of the grid groove (202) (i.e., the air groove (203)), and n2 is the refractive index of air.

[0085] If the cross-sectional surfaces of the grid ridge (201) and the grid groove (202) are designed as rectangles and air is used entirely as the filler for the grid groove (202), the manufacturing process of the grid structure and the average refractive index value The calculation is simplified.

[0086] Despite the simplified design, by adjusting the width ratio of the grid ridge (201) and the air groove (203) (i.e., the values ​​of K1 and K2), the average refractive index of different materials within the grid unit period of the grid structure It can still be effectively adjusted and controlled. This adjustment and control capability improves overall optical efficiency by enabling the grating structure to better meet different light transmission and coupling-out requirements.

[0087] The average refractive index of different materials within the grid unit period of the grid structure due to the introduction of air grooves (203) It should be noted that this decrease allows the peak of the diffraction efficiency curve to shift to a more suitable angular position. This helps to achieve more efficient beam coupling-out during the beam transmission process, which is particularly evident in the transmission and coupling-out of small-angle beams.

[0088] In another specific example, referring to FIG. 6, the cross-sectional views of the grid ridge (201) and the grid groove (202) are both rectangular, and the grid groove (202) is at least one filler (the one shown in FIG. 6). 1 It includes a filler (204)) and an air groove (203), and when the cross-sectional views of both the filler and the air groove (203) are rectangular, the average refractive index of different materials within the grid unit period of the grid structure silver =(K1*n1+K2*n2+K3*n3+……+K m *n m ) / P 1, where K1 is the width of the grid ridge (201), n1 is the refractive index of the grid ridge (201), K2 is the width of the air groove (203) excluding the filler in the grid groove (202), n2 is the refractive index of air, and K3~K m is the width of the different filler material filled within the grid groove (202), and n3~n m Each is the refractive index of a different filler material filled within the grid groove (202).

[0089] Referring further to FIG. 6, this design allows one or more fillers and air grooves (203) to be flexibly combined within the grid grooves (202), and by adjusting the width ratios of various materials, the average refractive index of different materials within the grid unit period of the grid structure It can be adjusted and controlled. This facilitates the optimization of light coupling-out in different application scenarios. At the same time, this precise adjustment and control capability helps to shift the peak of the grating's diffraction efficiency curve to an optimal position, thereby enabling more efficient and more uniform light coupling-out.

[0090] Optionally, the refractive index of the filler in the grid groove (202) and the refractive index of the grid ridge (201) may be the same. This design is equivalent to widening the width of the grid ridge (201) without changing the overall arrangement of the grid structure. This is the average refractive index of different materials within a grid unit period of the grid structure It provides a new approach to adjusting.

[0091] Of course, the refractive index of the filler material in the grid groove (202) and the refractive index of the grid ridge (201) may be different. In this case, a configuration in which a low-refractive-index material is filled into the grid groove (202) can be used while maintaining the air groove (203), so the average refractive index value of different materials within the grid unit period of the grid structure It is advantageous for reducing.

[0092] Average refractive index of different materials within the lattice unit period of the above lattice structure To adjust and control it more flexibly, the refractive indices of the grid ridge (201) and the grid groove (202) can be selected differently. In this case, by filling the grid groove (202) with a low refractive index material, the average refractive index value of the different materials within the grid unit period of the grid structure It can significantly reduce. This differentiated refractive index design [regarding] the average refractive index value Not only does it expand the adjustment and control range, but it also more precisely adjusts and controls the coupling-out efficiency of the light beam at different positions and different angles.

[0093] Regarding the feature of high coupling-out requirements for rays with large total internal reflection angles in the shear of the coupling-out region, the present application [describes] the average refractive index value of the grating structure A method is provided to shift the peak position of the efficiency curve by adjusting and controlling it. Below, the grid structure of the present application is analyzed by combining FIGS. 3 to 5 and FIGS. 7.

[0094] 1. Initial stage:

[0095] In the shear of the coupling-out region (2) above, since there is a coupling-out requirement only for light rays with a large total reflection angle, the peak position of the coupling-out efficiency curve must be set to a large angle position. Referring to FIG. 3, the average refractive index value of the grating structure The coupling-out requirements of the shear can be met by increasing the value and shifting the peak of the coupling-out efficiency curve to a diagonal position.

[0096] In one specific example, the refractive index n1 of the grid ridge (201) of the grid structure is 2.4, the refractive index n2 of the grid groove (202) is 1.4, and the duty cycle is 0.75. Average refractive index value According to the calculation formula for, the average refractive index value It is 2.15. Referring again to Fig. 3, the peak position of the coupling-out efficiency curve is located at approximately 59°.

[0097] 2. Intermediate stage:

[0098] As the light beam is transmitted to the rear end moving away from the coupling-in region (1), the reflection angle during propagation of the light beam gradually decreases, and the coupling-out requirements change accordingly. To satisfy this change, the average refractive index of the grating structure of the coupling-out region (2) The peak of the coupling-out efficiency curve must be gradually reduced to shift it to a smaller angle. At this time, the average refractive index value of the lattice structure It can be reduced, and referring to FIG. 4, by adjusting the duty cycle to adjust the area ratio of the two materials within the lattice structure, the size of the lattice ridge (201) can be reduced or the refractive index of the lattice ridge (201) or the lattice groove (202) can be reduced, and by adjusting the duty cycle to 0.5, the average refractive index value You can get 1.9.

[0099] Referring again to Fig. 4, the peak position of the coupling-out efficiency curve is located at approximately 57°.

[0100] 3. Post-stage:

[0101] When a light ray is transmitted to the rearmost end of the diffractive optical structure, the reflection angle is minimized; in this case, the peak of the coupling-out efficiency curve must shift to the minimum angle position to maximize the coupling-out efficiency of small-angle light rays. At this point, if the duty cycle is adjusted to 0.25, the average refractive index value of the grating structure It further decreases to 1.65, and referring to Fig. 5, the peak position of the coupling-out efficiency curve is located at 54°.

[0102] Average refractive index of different materials within the grid unit period of the grid structure of the coupling-out region (2) It should be noted that in order to further reduce [the problem], the present application also provides a method of introducing air grooves.

[0103] Because the refractive index of air (which is 1) is much lower than that of other media, when air is introduced as a filler, the average refractive index of different materials within a lattice unit period of the lattice structure It can significantly reduce, and the above average refractive index value Since it can be further reduced to 1.35, the peak of the coupling-out efficiency curve is shifted further toward the small angle direction, ensuring efficient coupling-out of the rearmost ray. Referring to Fig. 7, the peak position of the coupling-out efficiency curve is located at 44°–45°.

[0104] In some examples of the present application, referring to FIGS. 12 and 13, the lattice structure comprises a plurality of lattice ridges (201), and the plurality of lattice ridges (201) have a second period along a second direction. P At intervals of 2, and along the third direction, the third period PThey are arranged at intervals of 3, and a grid groove (202) is located between any two adjacent grid ridges (201), and at least a portion of the grid groove (202) is an air groove (203);

[0105] Average refractive index of different materials within the lattice unit period of the above lattice structure It is as follows,

[0106] ;

[0107] = + +… … + is the volume of the above grid ridge (201), and is the refractive index of the above-mentioned grid ridge (201), and is the volume of the air groove (203), and is the refractive index of air, and The silver filled within the grid groove (202) 1 It is the volume of the filler, and The silver filled within the grid groove (202) 1 It is the refractive index of the filler, and The silver filled within the grid groove (202) m It is the volume of the filler, and The silver filled within the grid groove (202) m It is the refractive index of the filler; =( P 2* P 3)* H , H is the height of the grid ridge (201) above.

[0108] This example of the present application relates to a two-dimensional lattice structure, wherein the average refractive index of different materials within a lattice unit period of the lattice structure is achieved by precisely controlling the material composition and volume within the lattice ridge (201) and the lattice groove (202). Implement a reasonable design for.

[0109] The grid groove (202) is located between adjacent grid ridges (201), and at least a portion of the grid groove (202) is an air groove (203). Of course, one or more other materials may be filled into the grid groove (202).

[0110] The average refractive index of different materials within a grid unit period of the grid structure is obtained by precisely adjusting the material composition and volume within the grid ridge (201) and grid groove (202). By adjusting and controlling it, the shift of the diffraction efficiency curve can be controlled. This helps improve the light coupling-out efficiency at a specific angle, and this is particularly important for improving the overall optical efficiency of the diffraction optical structure in augmented reality (AR) optics.

[0111] The two-dimensional lattice structure of this example of the present application improves diffraction efficiency and the overall optical performance of the diffraction optical structure by precisely controlling the material composition and volume distribution to precisely adjust and control the average refractive index of the lattice structure.

[0112] In some examples of the present application, referring to FIGS. 8 to 10, the lattice structure further comprises at least one layer of filler, and the refractive index of the filler and the lattice ridge (201) are different.

[0113] Referring to FIGS. 8 through 10, the grid structure may further include at least one layer of filler having a refractive index different from that of the grid ridge (201) (the filler may form a layer of filler covering the grid structure). This design introduces additional degrees of freedom in adjusting the refractive index.

[0114] Various manufacturing processes, such as ALD deposition, PVD deposition, and CVD deposition, can be used for the design of filler introduction. These processes can ensure that the optical performance of the lattice structure reaches expectations by precisely controlling the thickness of the formed filler.

[0115] In some examples of the present application, referring to FIG. 8, the at least one layer of filler is 1 It includes a filler (204), and the above 1 The filler material (204) is coated on the surface of the grid ridge (201) and on the groove walls and bottom of the grid groove (202), wherein the grid groove (202) is an air groove (203) and the 1 It includes a filler (204).

[0116] In this example of the present application, the lattice structure is 1 It further includes a filler (204), and the above 1 The filler material (204) is coated on the surface of the grid ridge (201) and on the groove walls and bottom of the grid groove (202), and some space within the grid groove (202) is still maintained as an air groove (203). Here, the 1 The filler material (204) may be a low refractive index material, and the above 1 The introduction of the filler (204) is the average refractive index of different materials within the grid unit period of the grid structure. It provides additional means for adjustment and control regarding. Suitable for 1 By selecting the refractive index of the filler, the average refractive index of different materials within the grid unit period of the grid structure By precisely adjusting it, the coupling-out efficiency curve of the above grid structure can be influenced.

[0117] Maintaining the air groove (203) ensures structural stability while further reducing the refractive index of the grid groove (202) portion.

[0118] In some examples of the present application, referring to FIG. 9, the at least one layer of filler is 2 It includes a filler (205), and the above 2 The filler material (205) is the above-mentioned 1 It is installed in the filler material (204), and within the grid groove (202) the above2 A filler (205) is included while an air groove (203) is maintained, and here, the above 1 Filler material (204) and the above 2 The refractive index of the filler material (205) is different.

[0119] Referring to FIG. 9, in this example, the above 1 Based on the filler material (204) 2 A filler material (205) is further added, and at the same time, some space within the grid groove (202) is maintained as an air groove (203). Here, the 1 Filler material (204) and 2 The refractive index of the filler material (205) is different.

[0120] my 1 A layer having a different refractive index from the filler (204) 2 By adding more filler material (205), the average refractive index of different materials within the grid unit period of the grid structure The adjustment and control range can be further expanded. This helps to precisely control coupling-out efficiency within a wider angular range. A design incorporating multiple layers of filler allows for more precise adjustment and control of the peak position and shape of the efficiency curve, enabling the elimination of specific requirements in different application scenarios.

[0121] In some examples of the present application, referring to FIG. 10, the at least one layer of filler is 3 It further includes a filler (206), and the above 3 The filler material (206) is the above-mentioned 1 The above-mentioned moving away from the filler (204) 2 The surface of the filler (205) is coated, and within the grid groove (202) the above 3 A filler (206) is further included, and the above 3 The filler material (206) is filled into the air groove (203); where, the 1 Filler material (204), the above 2Filler material (205) and the above 3 The refractive indices of the filler (206) are different from each other.

[0122] In this example, referring to FIG. 10, the lattice structure is 1 Filler (204), 2 Filler material (205) and 3 It further includes a filler (206), and the refractive indices of the three layers of materials are different from each other. When the three layers of fillers with different refractive indices are combined, the average refractive index of the different materials within the grid unit period of the grid structure It can be adjusted and controlled with the utmost precision. This provides strong support for precisely controlling the diffraction efficiency curve of the grating.

[0123] Furthermore, fillers with different refractive indices can exhibit different optical properties, such as different light transmittances and scattering characteristics. The combination of these properties allows for diverse optical performance under conditions where the lattice structure differs.

[0124] In summary, referring to FIGS. 8 through 10, in these three examples, the average refractive index of different materials within the grid unit period of the grid structure of the coupling-out region (2) is obtained through design means such as introducing fillers with different numbers and refractive indices and maintaining air grooves (203). It precisely adjusts and controls the optical performance and significantly improves optical performance. This design not only helps improve the overall optical efficiency of the diffractive optical structure but also provides more reliable and flexible technical support for applications in fields such as augmented reality.

[0125] According to another embodiment of the present application, a near-eye display device is provided. The near-eye display device includes an image source and a diffractive optical structure as described above, and a light ray emitted from the image source can be incident on a coupling-in region (1) of the diffractive optical structure.

[0126] Here, the image source is, for example, a projection light engine.

[0127] Here, the above diffraction optical structure is, for example, a diffraction optical waveguide.

[0128] The near-eye display device provided in the embodiment of the present application is, for example, an AR optical display device. Additionally, the AR optical display device is, for example, AR smart glasses or an AR smart helmet.

[0129] Specific embodiments of the near-eye display device according to the embodiments of the present application can be described by referring to each embodiment of the diffraction optical structure, and since they possess all the beneficial effects brought about by the technical solution means of at least the embodiments, they are not described in detail here.

[0130] The above examples focus on the differences between each example, and the different optimization features between each example can be combined to form a more desirable example as long as they do not contradict each other, and for the sake of brevity, they are not described repeatedly here.

[0131] Although some specific embodiments of this application have been described in detail through examples, those skilled in the art should understand that such examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that such embodiments may be modified without departing from the scope and spirit of this application. The scope of this application is limited by the appended claims. Explanation of the symbols

[0132] 1: Coupling-in region; 2: Coupling-out region; 3: Substrate; 201: Grid ridge; 202: Grid groove; 203: Air groove; 204: No 1 Filler; 205: Je 2 Filler; 206: Je 3 Filler material.

Claims

Claim 1 A diffractive optical structure comprises a substrate (3) and a coupling-in region (1) and a coupling-out region (2) installed on the substrate (3); the coupling-out region (2) comprises a grating structure, wherein the grating structure comprises a plurality of periodically arranged grating ridges (201) and grating grooves (202) between adjacent grating ridges (201), and the grating grooves (202) are filled with at least two materials having different refractive indices; and the average refractive index of the different materials within a grating unit period of the grating structure is and, 1.1< ≤2.4, and, here, V 1~ V m Each one 1 From the materials m It is the volume or area up to the material, and n 1~ n m Each one 1 From the materials m It is the refractive index up to the material, and V unitcell A diffractive optical structure characterized by having a volume or area of ​​a lattice unit period. Claim 2 In claim 1, the average refractive index of different materials within the grid unit period of the grid structure is 1.35≤ A diffractive optical structure characterized by ≤2.

15. Claim 3 A diffractive optical structure according to claim 1, wherein the substrate (3) comprises two opposing surfaces, and the coupling-in region (1) and the coupling-out region (2) are installed on at least one surface of the substrate (3); wherein the coupling-in region (1) couples an external light ray into the substrate (3); and the coupling-out region (2) couples the light ray out by dilating the pupil. Claim 4 In any one of claims 1 to 3, the grid structure has a first period along a first direction P It includes a plurality of grid ridges (201) arranged according to 1, wherein a grid groove (202) is located between any two adjacent grid ridges (201), and at least a portion of the grid groove (202) is an air groove (203); and the average refractive index of different materials within a grid unit period of the grid structure It is as follows, ;Here, = + +… … + is the longitudinal cross-sectional area of ​​the grid ridge (201), and is the refractive index of the above-mentioned grid ridge (201), and is the longitudinal cross-sectional area of ​​the air groove (203), and is the refractive index of air, and The silver filled within the grid groove (202) 1 It is the longitudinal cross-sectional area of ​​the filler, and The silver filled within the grid groove (202) 1 It is the refractive index of the filler, and The silver filled within the grid groove (202) m It is the longitudinal cross-sectional area of ​​the filler, and The silver filled within the grid groove (202) m It is the refractive index of the filler; = P 1* H , H A diffractive optical structure characterized by the height of the grating ridge (201) above. Claim 5 In any one of claims 1 to 3, the grid structure comprises a plurality of grid ridges (201), and the plurality of grid ridges (201) have a second period along a second direction. P At intervals of 2, and along the third direction, the third period P Arranged at intervals of 3, a grid groove (202) is located between any two adjacent grid ridges (201), and at least a portion of the grid groove (202) is an air groove (203); and the average refractive index of different materials within a grid unit period of the grid structure It is as follows, ; = + +… … + is the volume of the above grid ridge (201), and is the refractive index of the above-mentioned grid ridge (201), and is the volume of the air groove (203), and is the refractive index of air, and The silver filled within the grid groove (202) 1 It is the volume of the filler, and The silver filled within the grid groove (202) 1 It is the refractive index of the filler, and The silver filled within the grid groove (202) m It is the volume of the filler, and The silver filled within the grid groove (202) m It is the refractive index of the filler; =( P 2* P 3)* H , H A diffractive optical structure characterized by the height of the grating ridge (201) above. Claim 6 A diffractive optical structure according to any one of claims 1 to 3, wherein at least one layer of filler is coated on the lattice structure, and the refractive index of the filler and the refractive index of the lattice ridge (201) are different. Claim 7 In paragraph 6, the above at least one layer of filler is 1 It includes a filler (204), and the above 1 The filler material (204) is coated on the surface of the grid ridge (201) and on the groove walls and bottom of the grid groove (202), and the grid groove (202) is an air groove (203) and the 1 A diffraction optical structure characterized by including a filler (204). Claim 8 In paragraph 7, the above at least one layer of filler is 2 It further includes a filler (205), and the above 2 The filler material (205) is the above-mentioned 1 It is covered with a filler material (204), and the grid groove (202) is the above 2 The air groove (203) is maintained while further including a filler (205), and the above 1 Filler material (204) and the above 2 A diffraction optical structure characterized by different refractive indices of the filler material (205). Claim 9 In paragraph 8, the above at least one layer of filler is 3 It further includes a filler (206), and the above 3 The filler material (206) is the above-mentioned 1 The above-mentioned moving away from the filler (204) 2 The surface of the filler (205) is coated, and within the grid groove (202) the above 3 A filler (206) is further included, and the above 3 The filler material (206) is filled into the air groove (203); and the above 1 Filler material (204), the above 2 Filler material (205) and the above 3 A diffraction optical structure characterized by the fact that the refractive indices of the filler material (206) are different from each other. Claim 10 A near-eye display device comprising: an image source; and a diffractive optical structure according to any one of claims 1 to 3, wherein a light ray emitted from the image source can be incident on a coupling-in region (1) of the diffractive optical structure.

Images