Diffractive optical structures and near-eye display devices

Abstract

This invention provides a diffractive optical structure and a near-eye display device. The diffractive optical structure includes a waveguide layer, a protective layer, and a raised structure. The waveguide layer includes a substrate and a grating region and a non-grating region disposed on the substrate. A grating structure is disposed in the grating region. The protective layer is stacked on the side of the waveguide layer where the grating structure is disposed. The raised structure is disposed on the surface of the protective layer facing the waveguide layer. The position of the raised structure corresponds to the non-grating region. The raised structure extends towards the non-grating region. The minimum vertical distance between the end face of the raised structure away from the protective layer and the surface of the corresponding non-grating region is a preset air gap A. The sum of A and the height H of the raised structure in the direction perpendicular to the surface of the protective layer satisfies 50μm≤A+H≤150μm. When an external force is applied to the protective layer, the raised structure abuts against the corresponding non-grating region to transfer the stress to the non-grating region, thereby suppressing the deformation of the protective layer and preventing the grating structure from being squeezed.

Description

Technical Field

[0001] This application relates to the field of optical imaging and display technology, and more specifically, to a diffractive optical structure and a near-eye display device. Background Technology

[0002] In the field of AR (Augmented Reality) technology, diffractive waveguides are a common terminal form, and their lightweight experience is crucial. To achieve this goal, resin materials are often chosen to fabricate the light guiding layer and protective layer of diffractive waveguides due to their lightweight and easy-to-process properties, forming a resin waveguide architecture.

[0003] However, in existing resin waveguide architectures, the resin protective layer is mostly planar, see [link to relevant documentation]. Figure 1 The grating is protected by being attached to the light guide layer using a frame-mount method. However, because the resin material itself is relatively soft, and there is only an air layer between the grating and the resin protective layer, the resin protective layer is prone to deformation under external forces (such as wiping or pressing), which causes the grating to be squeezed and thus damages the waveguide performance. Utility Model Content

[0004] The purpose of this application is to provide a new technical solution for a diffractive optical structure and a near-eye display device.

[0005] In a first aspect, this application provides a diffractive optical structure, the diffractive optical structure comprising:

[0006] A waveguide layer includes a substrate and a grating region and a non-grating region disposed on the substrate, wherein a grating structure is provided in the grating region;

[0007] A protective layer is stacked on one side of the waveguide layer where the grating structure is provided;

[0008] A protruding structure is disposed on the surface of the protective layer facing the waveguide layer. The position of the protruding structure corresponds to the non-grating region. The protruding structure extends in the direction of the non-grating region. The minimum vertical distance between the end face of the protruding structure away from the protective layer and the corresponding surface of the non-grating region is a preset air gap A. The sum of the preset air gap A and the height H of the protruding structure in the direction perpendicular to the surface of the protective layer satisfies 50μm≤A+H≤150μm.

[0009] When an external force is applied to the protective layer, the protruding structure abuts against the corresponding non-grating area to transfer the stress to the non-grating area, thereby suppressing the deformation of the protective layer and preventing the grating structure from being squeezed.

[0010] Optionally, the preset air gap A satisfies: 20μm≤A≤50μm.

[0011] Optionally, the height H of the protrusion structure along the direction perpendicular to the surface of the protective layer satisfies 50μm≤H≤100μm.

[0012] Optionally, the protrusion structure has a curved or polygonal cross-section in the direction perpendicular to the waveguide layer.

[0013] Optionally, the protruding structure is configured in a one-to-one correspondence with the non-grating region on the waveguide layer.

[0014] Optionally, the protective layer has a groove structure at a position corresponding to the grating region, and a buffer cavity is formed between the groove structure and the grating region.

[0015] Optionally, the protective layer is made of a reinforced resin material, including polycarbonate (PC), modified polyurethane (PU), or polymethyl methacrylate (PMA).

[0016] Optionally, the protective layer and the waveguide layer are bonded and fixed together by a frame bonding method.

[0017] Optionally, the edge of the protective layer is provided with a protrusion structure corresponding to the non-grating area of ​​the edge of the waveguide layer, and an adhesive gap is formed between the protrusion structure and the edge of the waveguide layer. The protective layer and the waveguide layer are bonded and fixed by filling the adhesive gap with optical adhesive in a frame-attachment manner. The width of the adhesive layer formed by the frame-attachment method is 1mm to 2mm.

[0018] Optionally, the protective layer includes a flat plate body and the protruding structure and the groove structure integrally formed with the flat plate body.

[0019] Secondly, this application provides a near-eye display device, the near-eye display device comprising:

[0020] The diffractive optical structure as described in the first aspect.

[0021] The beneficial effects of this application are as follows:

[0022] The diffractive optical structure provided in this application provides a protective layer with protrusions corresponding to the non-grating regions on the waveguide layer, forming a suitable pre-set air gap between them. When external force is applied, the protrusions on the protective layer can tightly abut against the non-grating regions on the waveguide layer, effectively transferring stress to the non-grating regions. This optical design significantly enhances the overall deformation resistance of the protective layer, reducing its deformation under external force. Simultaneously, it effectively prevents external force from directly acting on the grating region, ensuring the grating structure is protected from compressive damage, thereby improving the stability of optical performance. Furthermore, the dimensions of the pre-set air gap and the protrusions are carefully designed to ensure that total internal reflection propagation of light within the waveguide substrate remains unaffected.

[0023] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0025] Figure 1 This is a schematic diagram of an existing resin waveguide architecture;

[0026] Figure 2 This is a schematic diagram of an existing resin waveguide architecture under external force.

[0027] Figure 3 This is one of the structural schematic diagrams of the diffraction optical structure provided in the embodiments of this application;

[0028] Figure 4 This is the second schematic diagram of the diffractive optical structure provided in the embodiments of this application;

[0029] Figure 5 This is the third schematic diagram of the diffraction optical structure provided in the embodiments of this application;

[0030] Figure 6 This is a structural decomposition diagram of the diffractive optical structure provided in the embodiments of this application.

[0031] Explanation of reference numerals in the attached figures:

[0032] 01. Light guide layer; 02. Resin protective layer; 03. Grating;

[0033] 1. Waveguide layer; 11. Substrate; 12. Grating region; 13. Non-grating region; 14. Grating structure; 141. Coupled-in grating; 142. Turning grating; 143. Coupled-out grating;

[0034] 2. Protective layer; 21. Raised structure; 22. Groove structure; 23. Flat body. Detailed Implementation

[0035] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0036] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0037] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0038] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0040] The diffractive optical structure and near-eye display device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0041] According to one embodiment of this application, a diffractive optical structure is provided, see [link to relevant documentation]. Figures 3 to 5The diffractive optical structure includes a waveguide layer 1, a protective layer 2, and a protrusion structure 21. The waveguide layer 1 includes a substrate 11 and a grating region 12 and a non-grating region 13 disposed on the substrate 11, wherein a grating structure 14 is disposed within the grating region 12. The protective layer 2 is stacked on the side of the waveguide layer 1 where the grating structure 14 is disposed. The protruding structure 21 is disposed on the surface of the protective layer 2 facing the waveguide layer 1. The position of the protruding structure 21 corresponds to the non-grating region 13. The protruding structure 21 extends toward the non-grating region 13. The minimum vertical distance between the end face of the protruding structure 21 away from the protective layer 2 and the corresponding surface of the non-grating region 13 is a preset air gap A. The sum of the preset air gap A and the height H of the protruding structure 21 along the direction perpendicular to the surface of the protective layer 2 satisfies 50μm≤A+H≤150μm. When an external force is applied to the protective layer 2, the protruding structure 21 abuts against the corresponding non-grating region 13 to transfer the stress to the non-grating region 13, thereby suppressing the deformation of the protective layer 2 and preventing the grating structure 14 from being squeezed.

[0042] The diffractive optical structure provided in this application embodiment can be applied to, for example, the field of AR (Augmented Reality) technology, providing a lightweight optical solution with high resistance to external forces for AR optical display devices. It effectively meets the requirements of AR optical display devices for thinner and lighter optical components, higher stability, and better optical performance, helping to improve the overall display effect and user experience of AR optical display devices.

[0043] Moreover, the application scope of the diffractive optical structure provided in this application embodiment can also be extended to other optical display fields such as VR (virtual reality), and it has wide applicability.

[0044] The diffractive optical structure provided in this embodiment benefits from its unique optical structure design. By setting a protruding structure 21 on the protective layer 2 corresponding to the non-grating region 13 on the waveguide layer 1 and forming a preset air gap A, it achieves multiple technical effects. For example, on the one hand, it significantly enhances the deformation resistance of the entire protective layer 2, effectively reduces deformation under external forces, protects the grating structure 14 from extrusion damage, and maintains stable optical performance. On the other hand, it ensures that light can still propagate through total internal reflection within the substrate 11 of the waveguide layer 1, avoiding adverse problems such as light leakage. This optical structure design provides reliable and high-performance optical support for AR or VR optical display devices, greatly improving the visual display effect and overall user experience of these optical devices.

[0045] As described in this application, the sum of the preset air gap A and the height H of the protrusion 21 along the direction perpendicular to the surface of the protective layer 2 needs to satisfy the following relationship: 50μm≤A+H≤150μm. This parameter design in this application maintains the air gap between the waveguide layer 1 and the protective layer 2 within the range of 50μm to 150μm.

[0046] The transmission of light within the substrate 11 of the waveguide layer 1 depends on total internal reflection. One of the functions of the air gap A+H designed in this application is to maintain the total reflection condition and prevent light leakage.

[0047] The range of air gap A+H designed in this application can also optimize the impact resistance and deformation suppression capability of the protective layer 2, thereby better protecting the grating structure 14 on the waveguide layer 1.

[0048] Optionally, the sum of the preset air gap A and the height H of the protruding structure 21 along the direction perpendicular to the surface of the protective layer 2 should satisfy 0μm < A + H ≤ 150μm. The above range, i.e., 50μm ≤ A + H ≤ 150μm, represents a further optimized design range.

[0049] For example, the sum of the preset air gap A and the height H of the protruding structure 21 along the direction perpendicular to the surface of the protective layer 2 can be 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, or 150μm. Specifically, it can be optimized based on the optical parameters of the waveguide layer 1, such as thickness and refractive index, as well as the morphological parameters of the grating.

[0050] It should be noted that if the value of A+H is too large, such as greater than 150 μm, it will result in an excessively thick protective layer 2 on one side of the waveguide layer 1, affecting the thinness and lightness of the entire diffractive optical structure. Therefore, the value of A+H should preferably not exceed 150 μm.

[0051] See Figures 3 to 5 The diffractive optical structure provided in this application embodiment includes at least one waveguide layer 1. The waveguide layer 1 is provided with a substrate 11, which serves as the supporting foundation for the entire diffractive optical structure, providing physical support for the grating structure 14 and other components such as the protective layer 2.

[0052] A grating region 12 is disposed on the substrate 11, and a grating structure 14 is arranged within the grating region 12. This grating structure 14 is the core region for realizing diffraction optics, responsible for specific modulation and transmission of light. See also Figure 6The grating structure 14 can be divided into an input grating 141, a transition grating 142, and an output grating 143 according to its function. It should be noted that the transition grating 142 can be selected or not according to actual needs, and this embodiment does not limit it.

[0053] On the surface of the substrate 11 where the grating structure 14 is disposed, in addition to the grating structure, there are also some non-grating regions 13 distributed thereon. See also Figure 3 These non-grating regions 13 are located, for example, between adjacent grating regions 12, or at the edge of the surface (i.e., the surface on the substrate 11 where the grating structure 14 is disposed). In this application, the non-grating regions 13 provide corresponding positions for the protrusions 21 on the protective layer 2. When the diffraction optical structure is subjected to external force, the protective layer 2 transmits the external force to the non-grating regions 13, at which time the non-grating regions 13 are able to bear and transmit stress.

[0054] See Figures 3 to 5 The diffractive optical structure provided in this embodiment of the application has a protective layer 2. The protective layer 2 is stacked on the side of the waveguide layer 1 with the grating structure 14, and the two form a stacked structure. The main function of the protective layer 2 is to protect the waveguide layer 1, and in particular, it can effectively prevent the grating structure 14 from being directly damaged by the external environment such as scratches and contamination.

[0055] A raised structure 21 is provided on the surface of the protective layer 2 facing the waveguide layer 1, and its position corresponds to the non-grating region 13 on the waveguide layer 1. When the protective layer 2 is subjected to external force, the raised structure 21 can tightly abut against the non-grating region 13 on the waveguide layer 1, thereby effectively transferring the stress to the non-grating region 13, thus suppressing the deformation of the protective layer 2 and preventing the grating structure 14 from being squeezed. In addition, when the protective layer 2 is not subjected to external force, a preset air gap A is formed between the end face of the raised structure 21 and the waveguide layer 1. This preset air gap A can ensure that light propagates through total internal reflection within the substrate 11.

[0056] In existing resin waveguide architectures, the resin protective layer 02 is mostly planar, see [reference]. Figure 1 The grating 03 on the light guide layer 01 is protected by a frame-mount method. However, due to the softness of the resin material and the fact that only an air layer exists between the grating 03 and the resin protective layer 02, the resin protective layer 02 is prone to deformation under external forces (such as wiping or pressing), causing the grating 03 to be squeezed and thus damaging the waveguide performance. See [link to relevant documentation]. Figure 2 .

[0057] The diffractive optical structure provided in the embodiments of this application is described in [reference]. Figures 3 to 5By providing the protruding structure 21 on the protective layer 2 corresponding to at least one non-grating region 13 of the waveguide layer 1, and forming a preset air gap, the following significant technical effects are achieved:

[0058] Enhancing the deformation resistance of the protective layer 2: When an external force is applied to the protective layer 2, the protrusions 21 on the protective layer 2 can play a role in stress dispersion and transmission, effectively dispersing and transmitting the stress to the non-grating region 13 on the waveguide layer 1. In this way, the overall deformation resistance of the protective layer 2 is significantly improved, and its deformation under external force is greatly reduced.

[0059] Effective protection of the grating structure 14 on the waveguide layer 1: This design effectively blocks external forces from directly acting on the grating region 12 on the waveguide layer 1, which can prevent the grating structure 14 from being damaged by compression, thereby improving the stability of the optical performance of the diffraction optical structure.

[0060] Maintaining the optical performance of the diffractive optical structure: The protruding structure 21 does not directly contact the non-grating region 13 on the substrate 11, but leaves a preset air gap. This reasonable planning and setting ensures that light can achieve total internal reflection propagation within the substrate 11 of the waveguide layer 1, and prevents light leakage caused by breaking the total internal reflection condition, thus effectively maintaining the total internal reflection optical performance of the diffractive optical structure.

[0061] In some examples of this application, the preset air gap A is 20μm≤A≤50μm.

[0062] When the preset air gap A is within the range of 0 < A ≤ 50 μm, when the protective layer 2 is subjected to external force, the protruding structure 21 can directly interact with the non-grating region 13 on the waveguide layer 1.

[0063] In this application, it is preferable that the preset air gap A is 20μm≤A≤50μm. This preset air gap A design ensures that the protruding structure 21 has sufficient space to transfer stress to the non-grating region 13 under load, while preventing stress transfer from becoming dispersed or failing due to an excessively large air gap. This gap design allows the protruding structure 21 and the non-grating region 13 to quickly contact and effectively transfer stress under load, dispersing the external force to the non-grating region 13, thereby significantly enhancing the overall deformation resistance of the protective layer 2 and reducing the deformation of the protective layer 2 under external force. However, if this preset air gap A is too large (e.g., >50μm), the protruding structure 21 may require a large displacement to contact the non-grating region 13 under load, which would reduce the efficiency of stress transfer and fail to effectively suppress the overall deformation of the protective layer 2 in a timely manner.

[0064] The preset air gap A is specified to be within the range of 20μm≤A≤50μm. This design also ensures that light propagates stably through total internal reflection within the substrate 11 of the waveguide layer 1. Due to the presence of this preset air gap, the end face of the protruding structure 21 will not directly contact the substrate 11, thereby effectively avoiding the disruption of total internal reflection conditions caused by contact, preventing light leakage, and ensuring that the diffractive optical structure can maintain its normal optical function.

[0065] Optionally, the preset air gap A can be 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm and 50μm.

[0066] In some examples of this application, the height H of the protrusion structure 21 along the direction perpendicular to the surface of the protective layer 2 satisfies 50μm≤H≤100μm.

[0067] In the design of the diffractive optical structure provided in this application, the height H of the protrusion structure 21 along the direction perpendicular to the surface of the protective layer 2 is designed to be 50μm to 100μm. This is closely related to the thickness of the air layer between the waveguide layer 1 and the protective layer 2, and plays a key role in adapting to the overall thickness of the diffractive optical structure.

[0068] From the perspective of lightweight and compact requirements, the overall thickness of the diffractive optical structure needs to be as thin as possible while meeting optical performance requirements to satisfy the needs of AR optical display devices. To adapt to the current trend towards thinner diffractive optical structures, the height H of the protrusion structure 21 in this example is set to 50μm to 100μm. This ensures that the protrusion structure 21 does not directly contact the corresponding non-grating region 13 and guarantees a suitable preset air gap A.

[0069] The waveguide layer 1 and the protective layer 2 have specific thickness requirements, and the height H of the protruding structure 21 must also be adapted to them. This avoids direct contact between the protruding structure 21 and the corresponding non-grating region 13. A suitable H value ensures stable bonding between the layers during assembly, avoiding problems such as the preset air gap A being too large or too small, thereby ensuring the optical stability and reliability of the diffractive optical structure.

[0070] Optionally, the height H of the protrusion structure 21 along the direction perpendicular to the surface of the protective layer 2 can be 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm and 100μm.

[0071] It should be noted that the sum of the height H of the protruding structure 21 along the direction perpendicular to the surface of the protective layer 2 and the preset air gap A should be ≤150μm. The preferred range for the preset air gap A is 20μm ≤ A ≤ 50μm.

[0072] See some examples in this application. Figures 3 to 5 The protrusion structure 21 has a curved or polygonal cross-section in the direction perpendicular to the waveguide layer 1.

[0073] Regarding mechanical support, see Figure 5 The advantage of the curved protrusion structure lies in its excellent mechanical dispersion characteristics. Specifically, when the protective layer 2 is subjected to external force, the curved design of the protrusion structure 21 can evenly distribute the stress to the surrounding area, avoiding stress concentration. For example, similar to an arched structure, it can withstand greater pressure without easily deforming, thereby effectively supporting the protective layer 2 and reducing the deformation of the protective layer 2 when subjected to external forces such as wiping or pressing, thus protecting the grating structure 14 from compression.

[0074] When the protruding structure 21 has a curved cross-section in the direction perpendicular to the waveguide layer 1, the corresponding preset air gap A is the minimum air gap formed between the protruding structure 21 and the non-grating region 13.

[0075] The protrusion structure 21 can also be a polygonal protrusion structure, for example, its cross-section ( Figure 3 and Figure 4 The longitudinal section shown can be quadrilateral, specifically a rectangle or a square, see [reference]. Figure 3 and Figure 4 These have stable geometric shapes. When subjected to external forces, they can provide effective support.

[0076] Furthermore, from a manufacturing process perspective, both curved and polygonal shaped protrusions 21 can be manufactured using existing mold-making and injection molding processes. Therefore, both types of protrusions are feasible in terms of manufacturing processes.

[0077] See some examples in this application. Figure 3 and Figure 5 The protruding structure 21 is configured in a one-to-one correspondence with the non-grating region 13 on the waveguide layer 1.

[0078] See the example provided in this application. Figure 3 and Figure 5The protruding structure 21 is configured in a one-to-one correspondence with the non-grating region 13 on the waveguide layer 1. This design significantly improves the mechanical properties of the protective layer 2 through a stress dispersion mechanism, enabling the protective layer 2 to better protect the grating structure 14 on the substrate 11.

[0079] For example, if the protective layer 2 is subjected to vertical pressure, the multiple protrusions 21 provided on it can disperse the force to the substrate 11 below the corresponding non-grating area 13, thereby greatly reducing the risk of overall bending of the protective layer 2.

[0080] The one-to-one correspondence design in this example ensures a uniform distribution of support force, guaranteeing that the grating structure 14 remains undamaged. Each protrusion 21 independently bears local stress, reducing the risk of structural failure due to overload of a single protrusion.

[0081] Of course, the raised structure 21 can also be provided only in certain non-grating areas 13. See, for details. Figure 4 A raised structure 21 can be provided in the non-grating area 13 between adjacent grating areas 12.

[0082] See some examples in this application. Figures 3 to 6 The protective layer 2 has a groove structure 22 at a position corresponding to the grating region 12, and a buffer cavity is formed between the groove structure 22 and the grating region 12.

[0083] When the protective layer 2 is subjected to external force (such as pressing, friction or drop impact), the buffer cavity between the groove structure 22 and the grating region 12 can protect the grating structure 14.

[0084] Light propagates within the substrate 11 of the waveguide layer 1 via total internal reflection. However, the contact between the protective layer 2 and the grating region 12 may introduce a sudden change in refractive index, disrupting the conditions for total internal reflection. The buffer cavity isolates both through an air medium (refractive index ≈ 1), ensuring a stable medium environment for the grating region 12 and preventing light leakage or a decrease in diffraction efficiency.

[0085] In some examples of this application, the protective layer 2 is made of a reinforced resin material, including polycarbonate (PC), modified polyurethane (PU), or polymethyl methacrylate (PMA).

[0086] In this example of the application, the protective layer 2 is made of a reinforced resin material, specifically including polycarbonate (PC), modified polyurethane (PU), or polymethyl methacrylate (PMA). These materials significantly improve the mechanical strength, impact resistance, environmental resistance, and optical compatibility of the protective layer 2 itself, providing reliable material support for the resin waveguide architecture.

[0087] This application selects PC, PU or PMA as the material for the protective layer 2. These materials not only solve the problem of poor impact resistance caused by the softness of traditional resin waveguides, but also significantly improve the reliability and durability of the diffractive optical structure through the synergistic design with the protruding structure 21.

[0088] In some examples of this application, the protective layer 2 and the waveguide layer 1 are bonded and fixed together by a frame bonding method.

[0089] In the example provided in this application, the protective layer 2 and the waveguide layer 1 can be bonded and fixed together in the edge area by means of optical adhesive in a frame-attach manner. This design utilizes the free space between the protective layer 2 and the waveguide layer 1 to achieve a stable connection, while avoiding interference of the optical adhesive with the diffraction function of the grating area 12, ensuring that the optical path transmission is not affected.

[0090] See some examples in this application. Figure 3 and Figure 5 The protective layer 2 has a raised structure 21 on its edge that corresponds to the non-grating region 13 on the edge of the waveguide layer 1, and an adhesive gap is formed between the edges of the raised structure 21. The protective layer 2 and the waveguide layer 1 are bonded and fixed by filling the adhesive gap with optical adhesive in a frame bonding manner. The width of the adhesive layer formed by the frame bonding method is 1mm to 2mm.

[0091] In the example provided in this application, the edge of the protective layer 2 is provided with a protrusion structure 21 corresponding to the non-grating region 13 of the waveguide layer 1. By filling the gap between the protrusion structure 21 and the edge of the waveguide layer 1 with optical adhesive and using a frame bonding process, the protrusion structure 21 is used to enhance the edge bonding strength, and the positioning of the non-grating region 13 avoids the influence of the optical adhesive on the grating function, thus achieving a balance between reliable fixation and optical performance.

[0092] In this example of the application, the protruding structure 21 serves both to connect the waveguide layer 1 and the protective layer 2, and to provide support. When external impact or pressure is applied to the surface of the protective layer 2, the protruding structure 21 can convert concentrated stress into multi-directional dispersed force, effectively resisting deformation and thus preventing deformation of the protective layer 2 due to localized stress.

[0093] 1mm is the minimum width required to ensure reliable adhesion. If the adhesive width is less than 1mm, the bonding area is too small, leading to insufficient bond strength. When the product is subjected to drops, vibrations, or thermal cycling, there is a risk of adhesive layer cracking and protective layer delamination. A width of 1mm to 2mm ensures sufficient bonding area to withstand various stresses, guaranteeing the product's durability and lifespan.

[0094] If the adhesive layer is too wide (>2mm), it is more prone to overflow under pressure during bonding. If adhesive overflows into the adjacent grating area, it will disrupt light transmission and diffraction. A width of 1mm to 2mm provides sufficient bonding area while minimizing this optical risk.

[0095] See some examples in this application. Figure 6 The protective layer 2 includes a flat plate body 23 and the protruding structure 21 and the groove structure 22 integrally formed with the flat plate body 23.

[0096] In the example provided in this application, the protective layer 2 adopts an integrated design of flat plate body 23, raised structure 21, and groove structure 22. The flat plate body 23 achieves overall adhesion and coverage with waveguide layer 1, while the raised structure 21 enhances the mechanical strength of the protective layer 2 and the groove structure 22 provides space for the protective grating, thus taking into account both optical protection performance and impact resistance reliability.

[0097] According to another embodiment of this application, a near-eye display device is provided, the near-eye display device including the diffractive optical structure as described above.

[0098] The near-eye display device is, for example, an AR optical display device.

[0099] The specific implementation of the near-eye display device in this application can refer to the above-described diffractive optical structure embodiment, and therefore has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0100] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0101] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above 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 modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A diffractive optical structure, characterized in that, include: The waveguide layer (1) includes a substrate (11) and a grating region (12) and a non-grating region (13) disposed on the substrate (11), wherein a grating structure (14) is provided in the grating region (12); A protective layer (2) is stacked on one side of the waveguide layer (1) on which the grating structure (14) is provided; A protruding structure (21) is disposed on the surface of the protective layer (2) facing the waveguide layer (1). The position of the protruding structure (21) corresponds to the non-grating region (13). The protruding structure (21) extends in the direction of the non-grating region (13). The minimum vertical distance between the end face of the protruding structure (21) away from the protective layer (2) and the corresponding surface of the non-grating region (13) is a preset air gap A. The sum of the preset air gap A and the height H of the protruding structure (21) in the direction perpendicular to the surface of the protective layer (2) satisfies 50μm≤A+H≤150μm. When an external force is applied to the protective layer (2), the protruding structure (21) abuts against the corresponding non-grating area (13) to transfer stress to the non-grating area (13), thereby suppressing the deformation of the protective layer (2) and preventing the grating structure (14) from being squeezed.

2. The diffractive optical structure according to claim 1, characterized in that, The preset air gap A satisfies the following condition: 20μm≤A≤50μm.

3. The diffractive optical structure according to claim 1 or 2, characterized in that, The height H of the protrusion structure (21) along the direction perpendicular to the surface of the protective layer (2) satisfies 50μm≤H≤100μm.

4. The diffractive optical structure according to claim 1, characterized in that, The protrusion structure (21) has a curved or polygonal cross-section in the direction perpendicular to the waveguide layer (1).

5. The diffractive optical structure according to claim 1, characterized in that, The protruding structure (21) is configured in a one-to-one correspondence with the non-grating region (13) on the waveguide layer (1).

6. The diffractive optical structure according to claim 1 or 5, characterized in that, The protective layer (2) has a groove structure (22) at a position corresponding to the grating region (12), and a buffer cavity is formed between the groove structure (22) and the grating region (12).

7. The diffractive optical structure according to claim 1, characterized in that, The protective layer (2) is made of a reinforced resin material, including polycarbonate (PC), modified polyurethane (PU), or polymethyl methacrylate (PMA).

8. The diffractive optical structure according to claim 1, characterized in that, The protective layer (2) and the waveguide layer (1) are bonded and fixed together by a frame bonding method.

9. The diffractive optical structure according to claim 1, 5, or 8, characterized in that, The edge of the protective layer (2) is provided with a protruding structure (21) corresponding to the non-grating region (13) of the edge of the waveguide layer (1), and an adhesive gap is formed between the protruding structure (21) and the edge of the waveguide layer (1). The protective layer (2) and the waveguide layer (1) are bonded and fixed by filling the adhesive gap with optical adhesive in a frame bonding manner. The width of the adhesive layer formed by the frame bonding method is 1mm to 2mm.

10. The diffractive optical structure according to claim 6, characterized in that, The protective layer (2) includes a flat plate body (23) and the protruding structure (21) and the groove structure (22) integrally formed with the flat plate body (23).

11. A near-eye display device, characterized in that, include: The diffractive optical structure as described in any one of claims 1-10.

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