Multilayer light transmission structure and optical display device

Abstract

The embodiment of the invention provides a multi-layer light transmission structure and optical display equipment. Wherein the multi-layer light transmission structure comprises a waveguide layer, a protective layer and a middle layer; a coupling-in grating and a coupling-out grating are arranged on the waveguide layer; the middle layer is arranged on at least one side of the waveguide layer and is adjacent to the waveguide layer; the protective layer is arranged on one side, deviating from the waveguide layer, of the middle layer; each layer in the multi-layer light transmission structure is set to have a specific refractive index, and after incident light enters the multi-layer light transmission structure, the multi-layer light transmission structure can guide light of different FOVs to be transmitted in different layers according to the refractive index difference between the different layers.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical imaging technology. More specifically, the embodiments of the present application relate to a multi-layer light transmission structure and an optical display device. Background Art

[0002] As the most common terminal form in the field of augmented reality (AR), the structure of diffraction optical waveguide usually consists of a waveguide layer (WG) and a protective layer (cover). Traditional waveguide architecture often adopts a frame-pasting method, that is, a protective layer is attached to the upper and lower sides of the waveguide layer or only on the grating side. However, when this design faces impact, such as in a falling ball experiment, the protective layer will continue to impact the waveguide layer after deformation, causing the waveguide to deform or even break, posing a safety hazard. Therefore, how to improve the stability and safety of the waveguide has become an urgent problem to be solved. Summary of the invention

[0003] The purpose of this application is to provide a new technical solution for a multi-layer light transmission structure and an optical display device.

[0004] In a first aspect, an embodiment of the present application provides a multi-layer light transmission structure, wherein the multi-layer light transmission structure comprises:

[0005] A waveguide layer, wherein an in-coupling grating and an out-coupling grating are provided on the waveguide layer;

[0006] an intermediate layer, disposed on at least one side of the waveguide layer and adjacent to the waveguide layer;

[0007] A protective layer, arranged on a side of the intermediate layer away from the waveguide layer;

[0008] Each layer of the multi-layer light transmission structure is configured to have a specific refractive index. After the incident light enters the multi-layer light transmission structure, the multi-layer light transmission structure can guide the light of different fields of view FOV to be transmitted in different layers according to the difference in refractive index between different layers;

[0009] After the incident light passes through the coupling grating, it can form at least a first field of view FOV light. The transmission condition that the first field of view FOV light must satisfy for total reflection propagation in the waveguide layer is: β3>arcsin(n adjacent-max / n3); wherein β3 is the angle of total reflection transmission of the first field of view FOV light in the waveguide layer, n3 is the refractive index of the waveguide layer, n adjacent-max is the maximum refractive index possessed by the intermediate layer adjacent to the waveguide layer.

[0010] Optionally, the light rays of the different fields of view FOV satisfy the total reflection condition when transmitted in their corresponding layers.

[0011] Optionally, the refractive index of the waveguide layer is greater than or equal to the refractive index of the intermediate layer, and the refractive index of the intermediate layer is greater than the refractive index of the protective layer.

[0012] Optionally, the protective layer, the intermediate layer and the waveguide layer are each provided as one layer; wherein the intermediate layer is stacked on one side of the waveguide layer, and the protective layer is stacked on the outer side of the intermediate layer.

[0013] Optionally, incident light with different incident angles is coupled into the waveguide layer through the coupling grating, and generates a first field of view FOV light, a second field of view FOV light and a third field of view FOV light respectively;

[0014] The light of the first field of view FOV is transmitted by total reflection in the waveguide layer and coupled out at the outcoupling grating;

[0015] The light of the second field of view FOV is refracted into the intermediate layer, is totally reflected in the intermediate layer, and is refracted again into the waveguide layer, and finally is incident on the outcoupling grating and coupled out;

[0016] The light of the third field of view FOV is refracted into the intermediate layer, refracted into the protective layer in the intermediate layer, refracted into the intermediate layer after total reflection in the protective layer, refracted into the waveguide layer again after being refracted by the intermediate layer, and finally incident on the outcoupling grating for outcoupling.

[0017] Optionally, the transmission condition that the second field of view FOV light must satisfy for total reflection propagation in the intermediate layer is: β2>arcsin(n1 / n2); wherein β2 is the angle of total reflection transmission of the second field of view FOV light in the intermediate layer, n2 is the refractive index of the intermediate layer, and n2=n adjacent-max , n1 is the refractive index of the protective layer.

[0018] Optionally, the transmission condition that the light of the third field of view FOV must meet when it is totally reflected and propagated in the protective layer is: β1>arcsin(1 / n1); wherein β1 is the angle of total reflection transmission of the light of the third field of view FOV in the protective layer, n1 is the refractive index of the protective layer, and the refractive index of air is 1.

[0019] Optionally, the multi-layer light transmission structure is a five-layer structure, the waveguide layer is provided as one, and the intermediate layer and the protective layer are provided as two each;

[0020] The two intermediate layers are respectively disposed on a first side and a second side opposite to the waveguide layer, and the two protection layers are respectively disposed on the outer sides of the two intermediate layers.

[0021] Optionally, the refractive index of the waveguide layer is n3, the refractive index of the intermediate layer located on the first side of the waveguide layer is n2, the refractive index of the intermediate layer located on the second side of the waveguide layer is n4, and the maximum value of n2 and n4 is n adjacent-max , and n3>n adjacent-max ;

[0022] The refractive index of the protective layer on the first side of the waveguide layer is n1, the refractive index of the protective layer on the second side of the waveguide layer is n5, n1<any one of n2 and n4, and n5<any one of n2 and n4.

[0023] Optionally, the incident light is incident from the first side of the waveguide layer, and after passing through the protective layer and the intermediate layer on the first side of the waveguide layer, the incident light is coupled into the waveguide layer through the coupling-in grating and generates a first field of view FOV light, and the first field of view FOV light is totally reflected and transmitted in the waveguide layer and coupled out at the coupling-out grating.

[0024] Optionally, the incident light is incident from the first side of the waveguide layer, and after passing through the protective layer and the intermediate layer on the first side of the waveguide layer, the incident light is coupled into the waveguide layer through the coupling grating and generates a second field of view FOV light;

[0025] The light of the second field of view FOV is refracted through the waveguide layer into the middle layer on the second side of the waveguide layer, and is refracted again into the waveguide layer after being totally reflected in the middle layer on this side, and finally incident on the outcoupling grating for outcoupling.

[0026] Optionally, a transmission condition that the light of the second field of view FOV must meet when it propagates through total reflection in the intermediate layer is: β2>the maximum value of arcsin(n1 / n2) and arcsin(n5 / n4); wherein β2 is the angle at which the light of the second field of view FOV is totally reflected in the intermediate layer.

[0027] Optionally, the incident light is incident from the first side of the waveguide layer, and after passing through the protective layer and the intermediate layer on the first side of the waveguide layer, the incident light is coupled into the waveguide layer through the coupling grating and generates a third field of view FOV light;

[0028] The light of the third field of view FOV is refracted by the waveguide layer into the middle layer on the second side of the waveguide layer, and is refracted in the middle layer on this side into the protective layer on the same side, and is refracted back to the middle layer on the second side of the waveguide layer after total reflection in the protective layer on this side, and then enters the waveguide layer again after being refracted through the middle layer on the second side of the waveguide layer, and finally is incident on the outcoupling grating for outcoupling.

[0029] Optionally, the transmission condition that the light of the third field of view FOV must meet when it propagates by total reflection in the protective layer is: β1>the maximum value of arcsin(1 / n1) and arcsin(1 / n5); wherein β1 is the angle at which the light of the third field of view FOV is transmitted in the protective layer.

[0030] Optionally, the multi-layer light transmission structure has an m-layer structure, and the multi-layer light transmission structure satisfies:

[0031] n1*sinθ1=n0*sinFOV;

[0032] n2*sinθ2=n1*sinθ1;

[0033] ……;

[0034] n (m+1) / 2 *sin(θ (m+1) / 2 )=n (m-1) / 2 *sin(θ (m-1) / 2 )+λ / Λ=n0*sinFOV+λ / Λ≥1;

[0035] Wherein, n0 is the refractive index of air, FOV is the field of view angle of the incident light, θ1 is the angle at which the incident light enters the protective layer, θ2 is the angle at which the incident light enters the intermediate layer from the protective layer, and n (m+1) / 2 is the refractive index of the waveguide layer, θ (m+1) / 2 is the angle at which the incident light enters the waveguide layer from the intermediate layer through the coupling-in grating, λ is the wavelength of the incident light, and Λ is the period of the coupling-in grating.

[0036] In a second aspect, an embodiment of the present application provides an optical display device, the optical display device comprising:

[0037] Optical machinery; and

[0038] The multi-layer light transmitting structure as described in the first aspect.

[0039] One beneficial effect of this application is:

[0040] The multi-layer light transmission structure provided in the embodiment of the present application is intended to improve the stability and safety of diffractive optical devices such as diffractive optical waveguide devices. Through a specially designed multi-layer architecture, the present application realizes the transmission of incident light between different layers. This design of the present application allows the entire multi-layer light transmission structure to efficiently transmit light of different fields of view (FOV) by regulating the refractive index of each layer, and realize effective transmission between different layers, thereby enriching the transmission path of light.

[0041] What is particularly important is that the present application adopts a laminated structure design, and this structural characteristic exhibits mechanical behavior similar to three-point bending when facing external impact. This unique mechanism minimizes the deformation borne by the waveguide layer, which not only significantly enhances the stability of the waveguide layer, but also effectively improves its overall safety. Therefore, even in complex or harsh usage environments, the multi-layer light transmission structure provided by the present application can ensure stable and reliable performance. It can be seen that the present application has shown significant beneficial effects in improving waveguide performance, and provides a new design idea for performance optimization and safety improvement of optical display devices.

[0042] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0044] Figure 1 A schematic diagram of a multi-layer light transmission structure provided in an embodiment of the present application;

[0045] Figure 2 One of the optical path diagrams of the multi-layer light transmission structure provided in the embodiment of the present application;

[0046] Figure 3 The second optical path diagram of the multi-layer light transmission structure provided in the embodiment of the present application;

[0047] Figure 4 The third optical path diagram of the multi-layer light transmission structure provided in the embodiment of the present application;

[0048] Figure 5 The fourth optical path diagram of the multi-layer light transmission structure provided in the embodiment of the present application;

[0049] Figure 6 This is the fifth optical path diagram of the multi-layer light transmission structure provided in the embodiment of the present application.

[0050] Description of reference numerals:

[0051] 1. Protective layer; 2. Intermediate layer; 3. Waveguide layer; 4. In-coupling grating; 5. Out-coupling grating;

[0052] S1, first field of view FOV light; S4, first outcoupled light; S5, second outcoupled light;

[0053] L1, second field of view FOV light; L4, third outcoupled light; L5, fourth outcoupled light;

[0054] P1, third field of view FOV light; P2, first transmission light; P3, second transmission light; P4, third transmission light; P5, fourth transmission light; P6, fifth transmission light; P7, sixth transmission light; P8, seventh transmission light; P9, eighth transmission light; P10, ninth transmission light; P11, tenth transmission light; P12, fifth outcoupling light; P13, sixth outcoupling light. DETAILED DESCRIPTION

[0055] 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 of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0056] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0057] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0058] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0059] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0060] The multi-layer light transmission structure and the optical display device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0061] According to one embodiment of the present application, a multi-layer light transmission structure is provided. Figures 1 to 5The multilayer light transmission structure comprises a waveguide layer 3, an intermediate layer 2 and a protective layer 1; an in-coupling grating 4 and an out-coupling grating 5 are arranged on the waveguide layer 3; the intermediate layer 2 is arranged on at least one side of the waveguide layer 3 and is adjacent to the waveguide layer 3; the protective layer 1 is arranged on the side of the intermediate layer 2 away from the waveguide layer 3; each layer in the multilayer light transmission structure is set to have a specific refractive index, and after the incident light enters the multilayer light transmission structure, the multilayer light transmission structure can guide the light of different fields of view FOV to be transmitted in different layers according to the refractive index difference between different layers; after the incident light passes through the in-coupling grating 4, at least a first field of view FOV light S1 can be formed, and the transmission condition that the first field of view FOV light S1 must meet for total reflection propagation in the waveguide layer 3 is: β3>arcsin(n adjacent-max / n3); wherein β3 is the angle of total reflection transmission of the first field of view FOV light S1 in the waveguide layer 3, n3 is the refractive index of the waveguide layer 3, n adjacent-max is the maximum refractive index in the intermediate layer 2 adjacent to the waveguide layer 3.

[0062] The multi-layer light transmission structure provided in the embodiment of the present application can be applied to, for example, the AR optical field. Of course, the multi-layer light transmission structure provided in the present application can also be applied to the VR and MR optical fields as needed.

[0063] The multi-layer light transmission structure provided in the embodiment of the present application is a diffractive optical waveguide architecture with a multi-layer structure, which is intended to enhance the structural stability and flexibility of the diffractive optical waveguide device in transmitting light.

[0064] The multi-layer light transmission structure provided in the embodiment of the present application combines a waveguide layer 3, an intermediate layer 2 and a protective layer 1, and can realize the transmission and control of light between different layers according to the wavelength and incident angle of the incident light.

[0065] The waveguide layer 3 provided in this application, see Figures 2 to 4 It is the core part of the whole multi-layer light transmission structure, responsible for carrying and transmitting the light S1 of the first field of view FOV. The waveguide layer 3 is designed to have a specific refractive index n3, which is crucial for the total reflection transmission of light.

[0066] An in-coupling grating 4 and an out-coupling grating 5 are provided on the waveguide layer 3. The in-coupling grating 4 is responsible for converting the incident light into light of a specific field of view (FOV) and introducing it into the waveguide layer 3 for transmission. The out-coupling grating 5 is responsible for coupling the incident light out of the waveguide layer 3 for subsequent use or display.

[0067] The intermediate layer 2 provided in the present application, which is disposed on at least one side of the waveguide layer 3, plays a key role of buffering and transition.

[0068] For example, see Figure 1 , the intermediate layer 2 can be provided with two, one of which is provided on the first side of the waveguide layer 3, and the other intermediate layer 2 is provided on the second side of the waveguide layer 3, so that the two intermediate layers 2 are symmetrically provided on both sides of the waveguide layer 3; wherein the refractive index of the intermediate layer 2 located on the first side of the waveguide layer 3 is defined as n2, for example, and the refractive index of the intermediate layer 2 located on the second side of the waveguide layer 3 is defined as n4, for example, it is worth noting that n2 and n4 can be the same or different.

[0069] When n2 and n4 are the same, n2=n4=n adjacent-max .

[0070] When n2 and n4 are different, the maximum value of n2 and n4 is n adjacent-max .

[0071] For example, see Figure 2 , the intermediate layer 2 may be provided with only one, that is, one intermediate layer 2 is provided on one side of the waveguide layer 3. In this example, the intermediate layer 2 is directly adjacent to the waveguide layer 3 (that is, the two are stacked), and at this time, the refractive index of the intermediate layer 2 is n adjacent-max .

[0072] It should be noted that n2 and n4 in the embodiment of the present application are general terms, and the multi-layer light transmission structure may include two or more intermediate layers 2 with different refractive indices. In other words, when the multi-layer light transmission structure of the embodiment of the present application has two or more intermediate layers 2, the refractive indices of different intermediate layers 2 may be the same or different.

[0073] The difference between the refractive index of the intermediate layer 2 and the refractive index of the waveguide layer 3 is a key factor in guiding the incident light to be transmitted between different layers. By controlling these refractive indices, the transmission and control of light of different fields of view FOV between different layers can be achieved.

[0074] For the multi-layer light transmission structure provided in the embodiment of the present application, when facing external impact, the intermediate layer 2 also plays a role in protecting the waveguide layer 3, and can absorb and disperse the impact force, thereby improving the stability and safety of the multi-layer light transmission structure.

[0075] The protective layer 1 provided in the present application is arranged on the side of the intermediate layer 2 away from the waveguide layer 3, see Figure 1 and Figure 2 In other words, the protective layer 1 may be an outer layer of a multi-layer light transmitting structure.

[0076] In the present application, one of the functions of the protective layer 1 is to protect the entire multi-layer light transmission structure from damage by the external environment, such as scratches, impacts, etc. The protective layer 1 can not only protect the waveguide layer 3, but also transmit light of a certain field of view FOV. In particular, the protective layer 1, the intermediate layer 2 and the waveguide layer 3 can transmit light of different fields of view FOV.

[0077] The protective layer 1 in the present application needs to have high hardness and wear resistance to ensure the stability and durability of the structure. The protective layer 1 should also have a specific refractive index to further optimize the transmission path and efficiency of light.

[0078] The multi-layer light transmission structure of the embodiment of the present application realizes the transmission and control of light between different layers through the combination and configuration of the waveguide layer 3, the intermediate layer 2 and the protective layer 1. This design not only improves the stability and safety of the multi-layer light transmission structure, but also enriches the transmission path of light, providing a new idea for the performance optimization of diffractive optical devices.

[0079] In the present application, by adjusting the refractive index of each layer in the multi-layer light transmission structure, it can be ensured that the entire multi-layer light transmission structure can efficiently transmit light of different fields of view (FOV) to meet the needs of different application scenarios.

[0080] In the present application, the refractive index of each layer of the multi-layer light transmission structure is set to ensure that a specific refractive index distribution is formed in the thickness direction of the multi-layer light transmission structure. For this multi-layer light transmission structure, these specially designed refractive indices of different layers are the core of achieving efficient and orderly propagation and distribution of light between layers. By regulating the design of the refractive index of each layer in the multi-layer light transmission structure, the principles of refraction and total reflection of light can be fully utilized, so that light of different fields of view FOV can be transmitted between or within different layers, thereby achieving more complex and efficient light transmission and distribution functions.

[0081] See also Figures 2 to 5 , incident light with different incident angles can be divided into light with multiple different fields of view (FOV) after passing through the coupling grating 4. Each layer in the multi-layer light transmission structure can be used to transmit light with at least one field of view FOV. This means that the incident light can be distributed to different layers of the multi-layer structure for transmission according to its FOV.

[0082] See also Figures 2 to 5When the FOV of the incident light is large, the first FOV light S1, the second FOV light L1, the third FOV light P1, etc. can be formed according to the wavelength and coupling angle of the incident light. In the multi-layer light transmission architecture of the present application, by regulating the refractive index of different layers, the lights of these different FOVs can be effectively managed and allocated to ensure that they can be transmitted along the predetermined path in the multi-layer structure, thereby achieving efficient light control.

[0083] The multi-layer light transmission structure provided in the embodiment of the present application can improve the structural stability of, for example, a diffractive waveguide device. Specifically, by adopting a multi-layer structure design, the waveguide layer 3 can be made more stable when facing external impact. This is because the multi-layer structure can disperse the impact force and reduce the deformation of the entire multi-layer light transmission structure, thereby improving the safety and stability of the multi-layer light transmission structure.

[0084] Each layer of the multi-layer light transmission structure provided in the embodiment of the present application is given a specific refractive index n. This design enables the incident light to be effectively guided to different layers for transmission according to the refractive index differences between different layers after entering the multi-layer light transmission structure. This layered transmission mechanism allows the light to more flexibly adjust its path during the propagation process, thereby meeting different FOV requirements.

[0085] It is worth mentioning that the multilayer light transmission structure of the present application converts the incident light into at least the first field of view FOV light S1 by coupling into the grating 4, and makes it propagate through total reflection in the waveguide layer 3. In this process, the angle β3 of the total reflection transmission of the first field of view FOV light S1 in the waveguide layer 3 needs to meet a specific condition, that is, β3>arcsin(n adjacent-max / n3). The setting of this condition ensures that the light can be transmitted stably and efficiently by total reflection in the waveguide layer 3.

[0086] The multi-layer light transmission structure of the present application further enhances the stability and safety of the structure through the provision of the intermediate layer 2. When facing external impact, the intermediate layer 2 can absorb and disperse the impact force like a "cushion", thereby protecting the waveguide layer 3 from damage. This laminated structure design enables the entire optical device to maintain more stable and reliable performance when facing complex or harsh use environments.

[0087] The multi-layer light transmission structure of the present application also protects the waveguide layer 3 and realizes the transmission of light in a certain field of view FOV through the provision of the protection layer 1.

[0088] The multi-layer light transmission structure provided in the embodiment of the present application realizes the transmission and control of light between different layers through a carefully designed layered transmission mechanism and a stable stacked structure, while improving the stability and safety of the multi-layer light transmission structure. This design not only provides a new idea for the performance optimization of diffractive optical devices, but also opens up a new way to improve the performance and ensure the safety of optical display devices.

[0089] In some examples of the present application, the light rays of the different fields of view FOV satisfy the total reflection condition when transmitting in their corresponding layers.

[0090] The multi-layer light transmission structure provided in the embodiment of the present application can control the transmission of light of different FOV sizes in each layer by setting the refractive index of different layers. This flexibility enables the multi-layer light transmission architecture to meet the needs of different application scenarios and achieve a wider FOV coverage.

[0091] In the multi-layer light transmission structure provided in the embodiment of the present application, each layer is specially designed to ensure that the light meets the total reflection condition during the transmission process, which helps to reduce the loss of light during the transmission process and improve the light transmission efficiency.

[0092] In some examples of the present application, the refractive index of the waveguide layer 3 is greater than or equal to the refractive index of the intermediate layer 2 , and the refractive index of the intermediate layer 2 is greater than the refractive index of the protective layer 1 .

[0093] Under this refractive index configuration mentioned in this example of the present application, the transmission path of the incident light in the multi-layer light transmission structure is optimized. In particular, the incident light can be refracted and reflected multiple times between the waveguide layer 3 and the intermediate layer 2 without immediately refracting out of the structure. This configuration also helps to reduce the loss of light during transmission and improve the efficiency of light transmission, which helps to achieve brighter and clearer image display. In addition, by adjusting the refractive index of different layers, the light of different FOV sizes transmitted in each layer can be controlled to meet the needs of different application scenarios.

[0094] In some examples of this application, see Figure 2 The protective layer 1, the intermediate layer 2 and the waveguide layer 3 are each set as one layer; wherein the intermediate layer 2 is stacked on one side of the waveguide layer 3, and the protective layer 1 is stacked on the outer side of the intermediate layer 2.

[0095] With the support of the intermediate layer 2 and the protective layer 1, the waveguide layer 3 can be better protected when facing external impact. The intermediate layer 2 plays a buffering role, which can absorb and disperse part of the impact force, thereby reducing the impact force directly acting on the waveguide layer 3, thereby enhancing the stability of the waveguide layer.

[0096] In traditional waveguide architectures, the waveguide layer is directly exposed to the external environment and is easily affected by external environmental factors (such as temperature, humidity, vibration, etc.), resulting in unstable optical performance.

[0097] In this example of the present application, the introduction of the intermediate layer 2 and the protective layer 1 provides one or more layers of protective barriers for the waveguide layer 3, effectively isolating the direct impact of the external environment on the waveguide layer 3, thereby improving the stability of the optical performance.

[0098] Due to the introduction of the intermediate layer 2 and the protective layer 1, additional transmission paths and interfaces are provided for light, so that the three-layer structure can support a wider viewing angle range. This is of great significance for applications such as augmented reality (AR) and virtual reality (VR) that require a large viewing angle display.

[0099] In this example of the present application, by introducing the intermediate layer 2 and the protective layer 1 and stacking them with the waveguide layer 3, the stability of the waveguide layer 3 is significantly enhanced, the stability of the optical performance is improved, the light transmission path is optimized, the field of view angle range is widened, the durability of the overall structure is improved, and the manufacturing process is simplified. These technical effects jointly improve the performance and application value of the multi-layer light transmission structure.

[0100] In some examples of this application, see Figure 2 , incident light with different incident angles is coupled into the waveguide layer 3 through the coupling grating 4, and generates a first field of view FOV light S1, a second field of view FOV light L1 and a third field of view FOV light P1 respectively;

[0101] The first field of view FOV light S1 is totally reflected and transmitted in the waveguide layer 3, and is coupled out at the coupling grating 5;

[0102] The light L1 of the second field of view FOV is refracted into the intermediate layer 2, and is refracted again into the waveguide layer 3 after being totally reflected in the intermediate layer 2, and finally incident on the outcoupling grating 5 for outcoupling;

[0103] The third field of view FOV light P1 is refracted into the intermediate layer 2, refracted into the protective layer 1 in the intermediate layer 2, refracted into the intermediate layer 2 after total reflection in the protective layer 1, refracted into the waveguide layer 3 again after being refracted by the intermediate layer 2, and finally incident on the outcoupling grating 5 for outcoupling.

[0104] In this example of the present application, through the three-layer light transmission structure, incident light of different wavelengths and incident angles can be coupled into the waveguide layer 3 via the coupling-in grating 4, and form the first field of view FOV light S1, the second field of view FOV light L1 and the third field of view FOV light P1 respectively. The transmission paths of these different field of view FOV lights in the three-layer light transmission structure are different, but they can all be coupled out at the coupling-out grating 5 in the end to realize the display of the image.

[0105] The three-layer light transmission structure provided in this example of the present application has a variety of light transmission paths, as follows:

[0106] See also Figure 2 , the first field of view FOV light S1 is directly transmitted by total reflection in the waveguide layer 3, and finally coupled out through the coupling grating 5. The second field of view FOV light L1 is refracted into the intermediate layer 2, and is refracted back to the waveguide layer 3 after total reflection in the intermediate layer 2, and finally coupled out through the coupling grating 5. The third field of view FOV light P1 will undergo a more complex refraction and total reflection process, and will pass through the waveguide layer 3, the intermediate layer 2 and the protective layer 1, but the third field of view FOV light will only be totally reflected in the protective layer 1, and refracted in other layers.

[0107] By adjusting the refractive index of each layer in the three-layer light transmission structure, and the design of the coupling-in grating 4 and the coupling-out grating 5 on the waveguide layer 3, the transmission path of light with different field angles can be accurately controlled. It can be seen that the introduction of the intermediate layer 2 and the protective layer 1 provides an additional interface for the refraction and total reflection of light, thereby realizing flexible regulation of the light transmission path.

[0108] Although the light transmission paths of different fields of view FOV are different, they can all be coupled out at the coupling grating 5.

[0109] By optimizing the design of the outcoupling grating 5, the outcoupling efficiency of light can be improved to ensure the clarity and brightness of the image.

[0110] The optical design scheme provided in this application realizes image display with a large field of view by designing light with different transmission paths. This is of great significance for applications such as augmented reality (AR) and virtual reality (VR) that require a large field of view display. Precise light transmission path control and optimized outcoupling grating design improve the outcoupling efficiency of light and the clarity and brightness of the image, which enables users to obtain a more realistic visual experience.

[0111] In this example of the present application, through the design of a multi-layer light transmission structure, effective transmission of light of different fields of view FOV between different layers is achieved. Specifically, the waveguide layer 3 can be used to transmit large-angle light, the intermediate layer 2 can transmit the central light, and the protective layer 1 transmits small-angle light. This design not only improves the flexibility of light transmission, but also enhances the stability of the entire structure.

[0112] The waveguide layer 3 is the core part of the multilayer light transmission structure and has a high refractive index n3. After the light is coupled into the waveguide layer 3 through the coupling grating 4, for example, the large-angle light, i.e., the first field of view FOV light S1, meets the total reflection condition and is transmitted by total reflection in the waveguide layer 3. The total reflection transmission of the large-angle light in the waveguide layer 3 ensures that the light can be efficiently propagated along the predetermined path, reduces light loss, and improves optical performance.

[0113] The intermediate layer 2 is arranged on one side or two opposite sides of the waveguide layer, and its refractive index is lower than that of the waveguide layer 3 but higher than that of the protective layer 1. When the angle of the incident light is moderate, that is, the second field of view FOV light L1, the light enters the intermediate layer 2 after being refracted once in the waveguide layer 3, and is transmitted by total reflection in the intermediate layer 3, and then refracted back to the waveguide layer 3 again.

[0114] The design of the intermediate layer 2 provides an additional transmission path for the light at the center angle, which helps to further widen the field of view. At the same time, the intermediate layer 2 also plays a role of buffering and supporting, enhancing the stability of the waveguide layer. By adjusting the refractive index of the intermediate layer 2, the transmission path and angle of the center light can be precisely controlled.

[0115] The protective layer 1 is arranged outside the intermediate layer 2, for example, it has the lowest refractive index. When the angle of the incident light is small, that is, the third field of view FOV light P1, the light enters the protective layer 1 after multiple refractions in the waveguide layer 3 and the intermediate layer 2, and is transmitted by total reflection in the protective layer 1, and then refracted back to the intermediate layer 2 and the waveguide layer 3 again.

[0116] The design of the protective layer 1 provides a transmission channel for small-angle light, preventing the light from directly escaping the structure. At the same time, the protective layer 1 also protects the entire multi-layer light transmission structure from damage by the external environment. By adjusting the refractive index of the protective layer 1, the transmission path and efficiency of small-angle light can be further optimized.

[0117] This design, in which the waveguide layer 3 transmits large-angle light, the intermediate layer 2 transmits central light, and the protective layer 1 transmits small-angle light, fully utilizes the characteristics of the multi-layer light transmission structure to achieve efficient transmission and precise control of light in different fields of view. This design not only improves the optical performance, but also enhances the stability and safety of the structure. In practical applications, this multi-layer light transmission structure can be widely used in augmented reality (AR), virtual reality (VR) and other fields, providing users with a more realistic and broad visual experience.

[0118] In some examples of the present application, the transmission condition that the second field of view FOV light L1 must satisfy for total reflection propagation in the intermediate layer (2) is: β2>arcsin(n1 / n2); wherein β2 is the angle of total reflection transmission of the second field of view FOV light L1 in the intermediate layer 2, n2 is the refractive index of the intermediate layer 2, and n2=n adjacent-max , n1 is the refractive index of the protective layer 1.

[0119] By adjusting the refractive index of the intermediate layer 2 and the incident angle β2 of the light during total reflection, the second field of view FOV light L1 can be effectively transmitted in the intermediate layer 2. This helps to broaden the field of view angle range of the entire multi-layer light transmission structure, so that more light can be effectively utilized.

[0120] The total reflection condition ensures that the light will not lose energy due to refraction when propagating in the intermediate layer 2, thereby improving the efficiency of light transmission.

[0121] The intermediate layer 2 serves as a transition layer between the waveguide layer 3 and the protective layer 1. Its existence not only facilitates light transmission, but also acts as a buffer during external impacts, thereby enhancing the stability of the entire structure.

[0122] In some examples of the present application, the transmission condition that the third field of view FOV light P1 must meet when it is totally reflected and propagated in the protective layer 1 is: β1>arcsin(1 / n1); wherein β1 is the angle of total reflection transmission of the third field of view FOV light P1 in the protective layer 1, n1 is the refractive index of the protective layer 1, and the refractive index of air is 1.

[0123] The total reflection condition ensures that the light will not escape into the air when propagating in the protective layer 1, thereby improving the utilization rate of the light, which is of great significance for improving the overall brightness and contrast of the optical display device.

[0124] The protective layer 1, as the outermost layer of the multi-layer light transmission structure, not only facilitates light transmission, but also effectively protects the internal waveguide layer 3 and the intermediate layer 2 from damage by the external environment. By selecting a suitable protective layer material and refractive index, the durability and stability of the entire structure can be further improved.

[0125] In the present application, by optimizing the refractive index and total reflection transmission conditions of the intermediate layer 2 and the protective layer 1, efficient transmission and precise control of light with different fields of view FOV in the multi-layer light transmission structure are achieved, the light transmission efficiency and utilization rate are improved, and the stability and durability of the entire structure are enhanced.

[0126] In some examples of this application, see Figure 1 The multi-layer light transmission structure is a five-layer structure, the waveguide layer 3 is set as one, the intermediate layer 2 and the protective layer 1 are set as two each; the two intermediate layers 2 are respectively arranged on the first side and the second side opposite to the waveguide layer 3, and the two protective layers 1 are respectively arranged on the outside of the two intermediate layers 2.

[0127] In this example of the present application, the multilayer light transmission structure is designed as a five-layer structure, specifically including a waveguide layer 3, two intermediate layers 2, and two protective layers 1. This design significantly enhances the performance of the multilayer light transmission structure and brings about various technical effects, which are specifically analyzed as follows.

[0128] The five-layer structure adopts a laminated design, in which the two intermediate layers 2 are arranged on both sides of the waveguide layer 3, and the protective layer 1 is arranged on the outside of each intermediate layer 2. This design can sandwich the waveguide layer 3 like a "sandwich" when facing external impact, effectively dispersing the impact force, thereby significantly enhancing the stability and safety of the waveguide layer 3. This laminated structure exhibits mechanical behavior similar to three-point bending when facing impact. This mechanism minimizes the deformation of the waveguide layer 3, further improving its stability and safety.

[0129] By adjusting the refractive index of each layer, the five-layer structure provided in this example of the present application can achieve effective transmission of incident light between different layers. The waveguide layer 3 is responsible for transmitting light with a large field of view FOV, the intermediate layer 2 transmits light with a medium field of view, and the protective layer 1 transmits light with a small field of view, ultimately forming a complete field of view. This layered transmission mechanism enables light to be transmitted along a predetermined path, improving the efficiency and flexibility of light transmission.

[0130] In the five-layer light transmission structure provided in this example of the present application, the light transmission of each layer meets the total reflection condition, avoiding too much light loss during the transmission process. This improves the utilization rate of light and ensures the clarity and brightness of the image display.

[0131] The five-layer light transmission structure provided in this example of the present application allows the existence of multiple light transmission paths, so that light of different fields of view can be transmitted between different layers. By adjusting the refractive index of each layer, the transmission path and angle of light of different fields of view FOV can be controlled, thereby meeting the field of view angle requirements of different scenes.

[0132] The introduction of the two intermediate layers 2 and the two protective layers 1 not only provides additional optical matching, but also enhances the mechanical support performance of the overall structure. This enables the multi-layer light transmission structure to maintain stable performance in the face of long-term use and external environmental interference. By optimizing the structural design and material selection, the five-layer structure in this application can reduce the risk of performance degradation due to long-term use and extend the service life of the optical display device.

[0133] In some examples of this application, see Figure 1 The refractive index of the waveguide layer 3 is n3, the refractive index of the intermediate layer 2 located on the first side of the waveguide layer 3 is n2, the refractive index of the intermediate layer 2 located on the second side of the waveguide layer 3 is n4, and the maximum value of n2 and n4 is n adjacent-max , and n3>n adjacent-max The refractive index of the protective layer 1 located on the first side of the waveguide layer 3 is n1, and the refractive index of the protective layer 1 located on the second side of the waveguide layer 3 is n5, n1<any one of n2 and n4, and n5<any one of n2 and n4.

[0134] For the five-layer light transmission structure, by adjusting the refractive indices of the waveguide layer 3, the intermediate layer 2 and the protective layer 1, a refractive index distribution of the entire five-layer light transmission structure that gradually decreases from the middle to the two sides is achieved.

[0135] Specifically, the waveguide layer 3 is the main channel for light transmission, and its refractive index n3 is designed to be higher than the maximum refractive index of the adjacent intermediate layer 2, that is, n3>n adjacent-max Such a design ensures that light is effectively transmitted in the waveguide layer 3 through a total reflection mechanism, reduces light leakage to surrounding layers, and improves light transmission efficiency.

[0136] The two interlayers 2 are located on both sides of the waveguide layer 3, and their refractive indices n2 and n4 are adjusted to ensure that the maximum value n adjacent-max It is still lower than the refractive index of the waveguide layer 3. This design is helpful to form a total internal reflection condition of the light in the waveguide layer 3.

[0137] The two protective layers 1 are located at the outermost sides of the waveguide layer 3, and their refractive indices are n1 and n5, respectively, which are designed to be lower than the refractive index of the intermediate layer 2 on either side. The design of the protective layer 1: first, further reduce the possibility of light leakage from the waveguide layer 1 to the outside; second, act as a physical barrier to protect the waveguide layer 3 from external physical damage or chemical erosion.

[0138] In some examples of this application, see Figure 3 The incident light is incident from the first side of the waveguide layer 3. After passing through the protective layer 1 and the intermediate layer 2 on the first side of the waveguide layer 3, the incident light is coupled into the waveguide layer 3 through the coupling-in grating 4 and generates a first field of view FOV light S1. The first field of view FOV light S1 is totally reflected and transmitted in the waveguide layer 3 and coupled out at the coupling-out grating 5.

[0139] See also Figure 3 The incident light is incident from the first side of the waveguide layer 3, and first passes through the protection layer 1 and the intermediate layer 2 on the first side. These two layers play the role of protecting the waveguide layer 3 and adjusting the direction of the light.

[0140] The coupling grating 4 is a key component for light to enter the waveguide layer 3. It effectively couples the incident light into the waveguide layer 3 through diffraction or refraction and generates the first field of view FOV light S1. The design of the coupling grating 4 is crucial to the coupling efficiency and coupling angle of the light.

[0141] The first field of view FOV light S1 is transmitted by total reflection mechanism in the waveguide layer 3. This requires that the refractive index of the waveguide layer 3 is higher than that of the adjacent layers such as the intermediate layer 2, so as to ensure that the light can be transmitted by total reflection in the waveguide layer 3 without leakage. Total reflection transmission allows the light to propagate over a long distance and with low loss in the waveguide layer 3, which is the basis for achieving efficient light transmission.

[0142] When the light S1 of the first field of view FOV propagates to the outcoupling grating 5, the light is coupled out of the waveguide layer 3. The outcoupling grating 5 guides the light out of the waveguide layer 3 through mechanisms such as diffraction.

[0143] This light transmission mode is more suitable when facing incident light with a relatively small field of view FOV, because it does not require a complex sub-path transmission design.

[0144] In some examples of this application, see Figure 4, the incident light is incident from the first side of the waveguide layer 3, and after passing through the protective layer 1 and the intermediate layer 2 on the first side of the waveguide layer 3, the incident light is coupled into the waveguide layer 3 through the coupling-in grating 4 and generates a second field of view FOV light L1; the second field of view FOV light L1 is refracted into the intermediate layer 2 on the second side of the waveguide layer 3 through the waveguide layer 3, and is refracted into the waveguide layer 3 again after being totally reflected in the intermediate layer 2 on this side, and finally is incident on the coupling-out grating 5 for coupling out.

[0145] See also Figure 4 , the incident light is incident from the first side of the waveguide layer 3, and first passes through the protective layer 1 and the intermediate layer 2. The coupling grating 4 couples the incident light into the waveguide layer 3 and generates the second field of view FOV light L1. The design of the coupling grating 4 is crucial to the coupling efficiency, coupling angle and field of view characteristics of the light.

[0146] See also Figure 4 When the light L1 of the second field of view FOV is transmitted in the waveguide layer 3, it is first refracted and enters the intermediate layer 2 on the second side of the waveguide layer 3. The light undergoes total reflection in the intermediate layer 2 on the second side of the waveguide layer 2. This requires a specific refractive index difference between the intermediate layer 2 on the second side of the waveguide layer 3 and the waveguide layer 3 to ensure that the light is totally reflected in the intermediate layer 2. After total reflection, the light will be refracted back to the waveguide layer 3 again and continue to be transmitted along a specific path. After multiple refractions and total reflections, the light L1 of the second field of view FOV is finally incident on the outcoupling grating 5 and coupled out of the waveguide layer 3.

[0147] It is worth noting that in this example of the present application, the field of view FOV of the first field of view FOV light is larger than the field of view of the second field of view FOV light. That is, the waveguide layer 3 can be used to transmit light with a large field of view FOV, while the intermediate layer 2 can be used to transmit light with a small field of view FOV.

[0148] The optical transmission method provided in this example of the present application is shown in Figure 4 , realizing the classified transmission of light with different fields of view FOV.

[0149] In some examples of the present application, the transmission condition that the second field of view FOV light L1 must meet when it propagates through total reflection in the intermediate layer 2 is: β2>the maximum value of arcsin(n1 / n2) and arcsin(n5 / n4); wherein β2 is the angle at which the second field of view FOV light L1 is totally reflected in the intermediate layer 2.

[0150] When the light L1 of the second field of view FOV is totally reflected and propagated in the intermediate layer 2, the condition that needs to be satisfied is β2>arcsin(n1 / n2) and the maximum value of arcsin(n5 / n4). Here, β2 is the angle of total reflection transmission of the light in the intermediate layer 2, n1 and n5 are the refractive indices of the protective layer 1 located on both sides of the waveguide layer 3, and n2 and n4 are the refractive indices of the intermediate layer 2 located on both sides of the waveguide layer 3. This condition is based on Snell's law and the principle of total reflection. Total reflection occurs when light is emitted from a denser medium (a medium with a higher refractive index) to a sparser medium (a medium with a lower refractive index), and the angle of incidence is greater than or equal to the critical angle. The critical angle can be calculated by arcsin(n 光疏 / n 光密 ) calculated.

[0151] In the multi-layer light transmission structure of the present application, the waveguide layer 3 is surrounded by the two intermediate layers 2 and the two protective layers 1. This structure provides a variety of possible transmission paths for light.

[0152] Since the refractive indexes n1 and n5 of the two protective layers 1 are smaller than the refractive indexes n2 and n4 of any intermediate layer 2, the light is more likely to be totally reflected at the interface between the intermediate layer 2 and the protective layer 1. However, when the light needs to be transmitted between the two intermediate layers 2 (such as the case of the light L1 of the second field of view FOV), the total reflection condition becomes more complicated because it depends on the refractive index of the intermediate layer 2 adjacent to the waveguide layer 3.

[0153] In order to ensure that the light L1 of the second field of view FOV is fully reflected and transmitted in the intermediate layer 2, it is necessary to compare the critical angles when the light enters the intermediate layer 2 from two different directions, and select the larger one as the basis for judging whether total reflection occurs, which increases the possibility of total reflection of the light.

[0154] By satisfying the total reflection condition, it can be ensured that the light L1 of the second field of view FOV is efficiently transmitted in the intermediate layer 2, reducing light leakage and loss, thereby improving the transmission efficiency of the multi-layer light transmission structure.

[0155] In some examples of this application, see Figure 5, the incident light is incident from the first side of the waveguide layer 3, and after passing through the protective layer 1 and the intermediate layer 2 on the first side of the waveguide layer 3, the incident light is coupled into the waveguide layer 3 through the coupling-in grating 4 and generates a third field of view FOV light P1; the third field of view FOV light P1 is refracted by the waveguide layer 3 and enters the intermediate layer 2 on the second side of the waveguide layer 3, and is refracted in the intermediate layer 2 on this side and enters the protective layer 1 on the same side, and is refracted back to the intermediate layer 2 on the second side of the waveguide layer 3 after total reflection in the protective layer 1 on this side, and then enters the waveguide layer 3 again after being refracted through the intermediate layer 2 on the second side of the waveguide layer 3, and finally is incident on the coupling-out grating 5 for coupling out.

[0156] In this example of the present application, see Figure 5 , describes a light transmission path, the specific process is as follows:

[0157] The incident light first passes through the protective layer 1 and the intermediate layer 2 on the first side of the waveguide layer 3 , which mainly play the role of protecting and guiding the light; then, the incident light is efficiently coupled into the waveguide layer 3 through the coupling grating 4 .

[0158] In the waveguide layer 3, the incident light is designed to generate a third field of view FOV light P1, and the third field of view FOV light P1 is then refracted by the waveguide layer 3, changing its propagation direction, and enters the intermediate layer 2 on the second side of the waveguide layer 3 to form a first transmission light P2.

[0159] In the intermediate layer 2 on the second side of the waveguide layer 3, the first transmission light P2 is refracted and enters the protective layer 1 on the second side of the waveguide layer 3 to form a second transmission light P3. The second transmission light P3 undergoes total reflection in the protective layer 1 to form a third transmission light P4, which helps the light to propagate stably in the protective layer while maintaining its field of view (FOV) and intensity.

[0160] After total reflection, the third transmission light P4 is refracted from the protective layer 1 on the second side of the waveguide layer 3 back to the intermediate layer 2 adjacent thereto to form a fourth transmission light P5; in the intermediate layer 2 on the second side of the waveguide layer 3, the fourth transmission light P5 is refracted again and re-enters the waveguide layer 3 to form a fifth transmission light P6.

[0161] In the waveguide layer 3, the fifth transmission light P6 continues to propagate, forming Figure 5 The sixth transmission light P7, the seventh transmission light P8, the eighth transmission light P9, the tenth transmission light P10 and the eleventh transmission light P11 are shown in FIG. 1 ; finally, the eleventh transmission light P11 reaches the coupling grating 5. At the coupling grating 5, the light is effectively coupled out, see Figure 5The fifth outcoupling light P12 and the sixth outcoupling light P13 complete the entire transmission process.

[0162] Through multi-layer structural design and matching of refractive indexes of each layer, this example of the present application achieves efficient management of light. The refraction and total reflection process of the incident light between layers is precisely controlled, thereby ensuring that the light can propagate along the expected path while reducing light loss. The multi-layer light transmission structure allows light with different fields of view FOV to be transmitted between different layers, which is very suitable for transmitting light with a large field of view without causing loss of field of view.

[0163] In some examples of this application, see Figure 5 , the transmission condition that the third field of view FOV light P1 must meet when it propagates through total reflection in the protective layer 1 is: β1>the maximum value of arcsin(1 / n1) and arcsin(1 / n5); wherein β1 is the angle at which the third field of view FOV light is transmitted in the protective layer 1.

[0164] When the light P1 of the third field of view FOV is totally reflected and propagated in the protective layer 1, the condition to be satisfied is the maximum value of β1>arcsin(1 / n1) and arcsin(1 / n5). Here, β1 is the angle of total reflection transmission of the light in the protective layer 1, and n1 and n5 are the refractive indices of the protective layers on both sides of the waveguide layer 3 respectively. This condition ensures that the light can be totally reflected at the interface between the protective layer 1 and the air without leaking into the external environment. The occurrence of total reflection depends on the incident angle of the light from the optically dense medium (protective layer 1, refractive index n1 or n5) to the optically sparse medium (air, refractive index of about 1) being greater than or equal to the critical angle.

[0165] In this example of the present application, since there are two protective layers 1, such as a protective layer 1 located on the first side of the waveguide layer 3 and a protective layer 1 located on the second side of the waveguide layer 3, and when their refractive indices are different (n1≠n5), it is necessary to take the maximum value of arcsin(1 / n1) and arcsin(1 / n5) as a condition for determining whether total reflection occurs. Total reflection ensures that light will not leak into the external environment in the protective layer 1, thereby improving the utilization rate of light.

[0166] The design of the multi-layer light transmission structure not only considers the light transmission efficiency, but also the stability of the structure. The protective layer 1, as the outermost structure, can protect the inner waveguide layer 3 and the intermediate layer 2 from external impact and damage.

[0167] In some examples of this application, see Figure 6 , the multi-layer light transmission structure has an m-layer structure, and the multi-layer light transmission structure satisfies:

[0168] n1*sinθ1=n0*sinFOV;

[0169] n2*sinθ2=n1*sinθ1;

[0170] ……;

[0171] n (m+1) / 2 *sin(θ (m+1) / 2 )=n (m-1) / 2 *sin(θ (m-1) / 2 )+λ / Λ=n0*sinFOV+λ / Λ≥1;

[0172] Wherein, n0 is the refractive index of air, FOV is the field of view angle of the incident light, θ1 is the angle at which the incident light enters the protective layer 1, θ2 is the angle at which the incident light enters the intermediate layer 2 from the protective layer 1, and n (m+1) / 2 is the refractive index of the waveguide layer 3, θ (m+1) / 2 is the angle at which the incident light enters the waveguide layer 3 from the intermediate layer 2 through the coupling-in grating 4 , λ is the wavelength of the incident light, and Λ is the period of the coupling-in grating 4 .

[0173] According to this example of the present application, it can be ensured that the designed multi-layer light transmission structure can maintain the integrity of the field of view FOV without any loss during the light transmission process. In addition, the stacked architecture design adopted by the multi-layer light transmission structure exhibits overall deformation characteristics when facing external impacts. This feature is in contrast to the situation where the layers may collide with each other in the traditional architecture, because it can effectively avoid direct collision and friction between layers. Therefore, when the multi-layer light transmission architecture is impacted, its stability is significantly improved, thereby greatly enhancing the safety of the overall structure. This design not only optimizes the light transmission path, but also greatly improves the durability and reliability of optical devices.

[0174] The multi-layer light transmission structure provided in the embodiment of the present application can achieve a light transmission capability of a field of view FOV of the same size as that of a traditional waveguide architecture.

[0175] The multi-layer light transmission structure provided in the embodiment of the present application is designed as a five-layer structure, see Figure 1 The multi-layer light transmission structure is based on the waveguide layer 3, and the intermediate layer 2 and the protective layer 1 are alternately arranged on both sides of the waveguide layer 3. The intermediate layers 2 on both sides of the waveguide layer 3 can be the same or different. The protective layers 1 on both sides of the waveguide layer 3 can be the same or different.

[0176] According to another embodiment of the present application, an optical display device is provided, wherein the optical display device includes an optical engine and the multi-layer light transmitting structure as described above.

[0177] The optical machine is used to emit projection light, which is also the incident light mentioned in the above embodiment.

[0178] The optical display device provided in the embodiment of the present application is a near-eye display device, for example, an AR optical display device. The types of AR optical display devices include AR smart glasses or AR smart helmets.

[0179] The above embodiments focus on 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. Considering the simplicity of the text, they will not be repeated here.

[0180] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A multi-layer light transmission structure, characterized in that: include: A waveguide layer (3), wherein an in-coupling grating (4) and an out-coupling grating (5) are provided on the waveguide layer (3); an intermediate layer (2), arranged on at least one side of the waveguide layer (3) and adjacent to the waveguide layer (3); A protective layer (1) is arranged on a side of the intermediate layer (2) facing away from the waveguide layer (3); Each layer of the multi-layer light transmission structure is configured to have a specific refractive index. After the incident light enters the multi-layer light transmission structure, the multi-layer light transmission structure can guide the light of different fields of view FOV to be transmitted in different layers according to the difference in refractive index between different layers; After the incident light passes through the coupling grating (4), at least a first field of view FOV light (S1) can be formed. The transmission condition that the first field of view FOV light (S1) must satisfy for total reflection propagation in the waveguide layer (3) is: β3>arcsin(n adjacent-max / n3); wherein β3 is the angle of total reflection transmission of the first field of view FOV light (S1) in the waveguide layer (3), n3 is the refractive index of the waveguide layer (3), n adjacent-max is the maximum refractive index in the intermediate layer (2) adjacent to the waveguide layer (3).

2. The multi-layer light transmission structure according to claim 1, characterized in that: The light rays of the different fields of view FOV satisfy the total reflection condition when transmitted in their corresponding layers.

3. The multi-layer light transmission structure according to claim 1, characterized in that: The refractive index of the waveguide layer (3) is greater than or equal to the refractive index of the intermediate layer (2), and the refractive index of the intermediate layer (2) is greater than the refractive index of the protective layer (1).

4. The multi-layer light transmission structure according to claim 3, characterized in that: The protective layer (1), the intermediate layer (2) and the waveguide layer (3) are each provided as one layer; wherein the intermediate layer (2) is stacked on one side of the waveguide layer (3), and the protective layer (1) is stacked on the outer side of the intermediate layer (2).

5. The multi-layer light transmission structure according to claim 4, characterized in that: Incident light with different incident angles is coupled into the waveguide layer (3) through the coupling grating (4), and generates a first field of view FOV light (S1), a second field of view FOV light (L1) and a third field of view FOV light (P1) respectively; The first field of view FOV light (S1) is totally reflected and transmitted in the waveguide layer (3), and is coupled out at the coupling grating (5); The light (L1) of the second field of view FOV is refracted into the intermediate layer (2), is totally reflected in the intermediate layer (2), is refracted again into the waveguide layer (3), and finally is incident on the outcoupling grating (5) to be outcoupled; The third field of view FOV light (P1) is refracted into the intermediate layer (2), refracted in the intermediate layer (2) and enters the protective layer (1), refracted into the intermediate layer (2) after total reflection in the protective layer (1), refracted again into the waveguide layer (3) after being refracted by the intermediate layer (2), and finally incident on the outcoupling grating (5) for outcoupling.

6. The multi-layer light transmission structure according to claim 5, characterized in that: The transmission condition that the second field of view FOV light (L1) must satisfy for total reflection propagation in the intermediate layer (2) is: β2>arcsin(n1 / n2); wherein β2 is the angle of total reflection transmission of the second field of view FOV light (L1) in the intermediate layer (2), n2 is the refractive index of the intermediate layer (2), and n2=n adjacent-max , n1 is the refractive index of the protective layer (1).

7. The multi-layer light transmission structure according to claim 5 or 6, characterized in that: The transmission condition that the third field of view FOV light (P1) must meet when it is totally reflected and propagated in the protective layer (1) is: β1>arcsin(1 / n1); wherein β1 is the angle of totally reflected transmission of the third field of view FOV light (P1) in the protective layer (1), n1 is the refractive index of the protective layer (1), and the refractive index of air is 1.

8. The multi-layer light transmission structure according to claim 3, characterized in that: The multi-layer light transmission structure is a five-layer structure, the waveguide layer (3) is provided as one, and the intermediate layer (2) and the protective layer (1) are provided as two each; The two intermediate layers (2) are respectively arranged on a first side and a second side opposite to the waveguide layer (3), and the two protective layers (1) are respectively arranged on the outer sides of the two intermediate layers (2).

9. The multi-layer light transmission structure according to claim 8, characterized in that: The refractive index of the waveguide layer (3) is n3, the refractive index of the intermediate layer (2) located on the first side of the waveguide layer (3) is n2, the refractive index of the intermediate layer (2) located on the second side of the waveguide layer (3) is n4, and the maximum value of n2 and n4 is n adjacent-max , and n3>n adjacent-max ; The refractive index of the protective layer (1) located on the first side of the waveguide layer (3) is n1, and the refractive index of the protective layer (1) located on the second side of the waveguide layer (3) is n5, n1<any one of n2 and n4, and n5<any one of n2 and n4.

10. The multi-layer light transmission structure according to claim 9, characterized in that: The incident light is incident from the first side of the waveguide layer (3), and after passing through the protective layer (1) and the intermediate layer (2) on the first side of the waveguide layer (3), the incident light is coupled into the waveguide layer (3) through the coupling-in grating (4) and generates a first field of view FOV light (S1), and the first field of view FOV light (S1) is totally reflected and transmitted in the waveguide layer (3) and coupled out at the coupling-out grating (5).

11. The multi-layer light transmission structure according to claim 10, characterized in that: The incident light is incident from the first side of the waveguide layer (3), and after passing through the protective layer (1) and the intermediate layer (2) on the first side of the waveguide layer (3), the incident light is coupled into the waveguide layer (3) through the coupling grating (4) and generates a second field of view FOV light (L1); The light (L1) of the second field of view FOV is refracted through the waveguide layer (3) into the middle layer (2) on the second side of the waveguide layer (3), and is refracted again into the waveguide layer (3) after being totally reflected in the middle layer (2) on the side, and finally incident on the outcoupling grating (5) for outcoupling.

12. The multi-layer light transmission structure according to claim 11, characterized in that: The transmission condition that the second field of view FOV light (L1) must meet when it is totally reflected and propagated in the intermediate layer (2) is: β2>the maximum value of arcsin(n1 / n2) and arcsin(n5 / n4); wherein β2 is the angle at which the second field of view FOV light (L1) is totally reflected and transmitted in the intermediate layer (2).

13. The multi-layer light transmission structure according to claim 11 or 12, characterized in that: The incident light is incident from the first side of the waveguide layer (3), and after passing through the protective layer (1) and the intermediate layer (2) on the first side of the waveguide layer (3), the incident light is coupled into the waveguide layer (3) through the coupling grating (4) and generates a third field of view FOV light (P1); The light (P1) of the third field of view FOV is refracted by the waveguide layer (3) and enters the intermediate layer (2) on the second side of the waveguide layer (3), and is refracted in the intermediate layer (2) on the side and enters the protective layer (1) on the same side, and is refracted back to the intermediate layer (2) on the second side of the waveguide layer (3) after total reflection in the protective layer (1) on the side, and then enters the waveguide layer (3) again after being refracted by the intermediate layer (2) on the second side of the waveguide layer (3), and finally is incident on the outcoupling grating (5) for outcoupling.

14. The multi-layer light transmission structure according to claim 13, characterized in that: The transmission condition that the third field of view FOV light (P1) must meet when it propagates by total reflection in the protective layer (1) is: β1>the maximum value of arcsin(1 / n1) and arcsin(1 / n5); wherein β1 is the angle at which the third field of view FOV light is transmitted in the protective layer (1).

15. The multi-layer light transmission structure according to claim 1, characterized in that: The multi-layer light transmission structure has an m-layer structure, and the multi-layer light transmission structure satisfies: n1*sinθ1=n0*sinFOV; n2*sinθ2=n1*sinθ1; ……； n (m+1) / 2 *sin(θ (m+1) / 2 )=n (m-1) / 2 *sin(θ (m-1) / 2 )+λ / Λ=n0*sinFOV+λ / Λ≥1; Wherein, n0 is the refractive index of air, FOV is the field of view angle of the incident light, θ1 is the angle at which the incident light enters the protective layer (1), θ2 is the angle at which the incident light enters the intermediate layer (2) from the protective layer (1), and n (m+1) / 2 is the refractive index of the waveguide layer (3), θ (m+1) / 2 is the angle at which the incident light enters the waveguide layer (3) from the intermediate layer (2) through the coupling-in grating (4), λ is the wavelength of the incident light, and Λ is the period of the coupling-in grating (4).

16. An optical display device, characterized in that: include: Optical machine; and The multilayer light transmitting structure according to any one of claims 1 to 15.

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