Diffractive optical structure, non-coupling region diffraction efficiency regulation and control method and optical equipment

Abstract

The embodiment of the invention discloses a diffractive optical structure, a method for regulating and controlling the diffraction efficiency of a non-coupling-in region and optical equipment. The diffractive optical structure comprises a substrate, and at least one coupling-in region and at least one coupling-out region which are arranged on the substrate; wherein the coupling-in area is used for coupling external light rays into the substrate, and the coupling-out area is used for performing pupil expansion on the light rays and coupling out the light rays; the coupling-out area is provided with a coupling-out grating with a residual layer, and the residual layer has a set thickness change trend at different positions of the coupling-out grating so as to regulate and control the coupling-out intensity of light; the refractive indexes of the residual layer and the substrate are different, the refractive index difference between the residual layer and the substrate is n, and n is larger than or equal to 0.1 and smaller than or equal to 0.8; the coupling-out area is configured to regulate and control the diffraction efficiency curve peak position of the coupling-out grating through the thickness change trend of the residual layer in the process that light is transmitted in the length direction of the diffractive optical structure.

Description

Technical Field

[0001] The present application belongs to the field of augmented reality (AR) technology. Specifically, the present application relates to a diffraction optical structure, a method for regulating the diffraction efficiency in a non-coupling zone, and an optical device. Background Art

[0002] With the continuous development of AR technology, the requirements for the optical efficiency of diffraction waveguides are increasing. In a diffraction waveguide, the coupling-in area is responsible for introducing external light into the waveguide, while the coupling-out area is responsible for expanding the pupil and coupling out the light. Among them, the diffraction efficiency regulation of the non-coupling area has become a key factor affecting the overall efficiency. Traditional control methods often find it difficult to achieve precise control of the diffraction efficiency curve, resulting in uneven distribution of light in the coupling-out area, affecting the display effect of the AR device. Therefore, how to effectively regulate the diffraction efficiency of the non-coupling area to improve the overall efficiency and uniformity of the diffraction optical waveguide has become a problem that needs to be solved urgently. Summary of the invention

[0003] The purpose of the present application is to provide a diffractive optical structure, a method for regulating the diffraction efficiency in a non-coupling zone, and a new technical solution for an optical device.

[0004] According to a first aspect of the present application, an embodiment of the present application provides a diffractive optical structure, the diffractive optical structure comprising a substrate and:

[0005] At least one coupling region, used to couple external light into the substrate;

[0006] At least one outcoupling region, used to expand the pupil of the light and couple it out;

[0007] The outcoupling region is provided with an outcoupling grating having a residual layer, and the residual layer has a set thickness variation trend at different positions of the outcoupling grating, so as to adjust the outcoupling intensity of the light;

[0008] The residual layer and the substrate have different refractive indices, and the difference in refractive index between the two is △n, 0.1≤△n≤0.8;

[0009] The outcoupling zone is configured to, during the transmission of light along the length direction of the diffraction optical structure, regulate the peak position of the diffraction efficiency curve of the outcoupling grating by adjusting the thickness variation trend of the residual layer, so as to achieve uniform outcoupling of light at different positions of the outcoupling zone.

[0010] Optionally, a refractive index difference Δn between the residual layer and the substrate is: 0.2≤Δn≤0.5.

[0011] Optionally, during the transmission of the light along the length direction of the diffractive optical structure, the thickness of the residual layer gradually decreases, so that the peak position of the diffraction efficiency curve of the outcoupling grating gradually moves from a large angle to a small angle along the transmission path of the light.

[0012] Optionally, the thickness of the residual layer is RSL, RSL*Δn=C, C is a constant, and 2mm≤C≤60mm.

[0013] Optionally, the thickness of the residual layer is RSL, and 10nm≤RSL≤300nm.

[0014] Optionally, the residual layer is made of glue.

[0015] Optionally, the residual layer is made of an inorganic material, and the inorganic material includes titanium oxide, aluminum oxide, silicon oxide or silicon nitride.

[0016] Optionally, in the outcoupling region, the outcoupling grating includes a front end, a middle portion and a rear end;

[0017] The thickness of the residual layer at the front end of the out-coupling grating is 100 nm to 300 nm, and the peak position of the diffraction efficiency curve of the out-coupling grating is 65° to 85°;

[0018] The thickness of the residual layer in the middle of the out-coupling grating is 50nm-150nm, and the peak position of the diffraction efficiency curve of the out-coupling grating is 50°-65°;

[0019] The thickness of the residual layer at the rear end of the out-coupling grating is 5nm-15nm, and the peak position of the diffraction efficiency curve of the out-coupling grating is between 30° and 50°.

[0020] Optionally, the diffractive optical structure further comprises a turning zone, wherein the turning zone is disposed on the substrate and located between the optical paths of the coupling-in zone and the coupling-out zone, and the residual layer can extend from the coupling-out zone to at least a portion of the turning zone.

[0021] According to a second aspect of the present application, an embodiment of the present application provides a method for regulating the diffraction efficiency of a non-coupling region, the regulating method being used for a diffractive optical structure, the diffractive optical structure comprising a substrate and at least one coupling region and at least one decoupling region disposed on the substrate, the decoupling region comprising a decoupling grating having a residual layer, and the residual layer and the substrate have different refractive indices, and the refractive index difference between the two is △n, 0.1≤△n≤0.8;

[0022] The method for controlling the diffraction efficiency includes:

[0023] In the outcoupling region, according to the light transmission path and the required outcoupling angle, the thickness variation trend of the residual layer at each position of the outcoupling grating is determined to adjust the peak position of the diffraction efficiency curve of the outcoupling grating;

[0024] The external light is coupled into the substrate through the coupling-in region, and the light is totally reflected in the substrate and transmitted to the coupling-out region;

[0025] The peak position of the diffraction efficiency curve of the out-coupling grating is regulated by the residual layer so that the peak value of the diffraction efficiency curve can change according to a predetermined trend during the transmission of light along the length direction of the diffraction optical structure, thereby coupling out evenly at different positions of the out-coupling area.

[0026] According to a third aspect of the present application, an embodiment of the present application provides an optical device, the optical device comprising:

[0027] the image source; and

[0028] In the diffractive optical structure as described in the first aspect, the light emitted by the image source can be incident on the coupling-in region.

[0029] One beneficial effect of the embodiments of the present application is:

[0030] The diffraction optical structure provided in the embodiment of the present application includes a substrate, a coupling-in region, a coupling-out region and a residual layer for making a grating, wherein the residual layer is located in the coupling-out region on the substrate; by adjusting the refractive index difference between the residual layer and the substrate, the peak position of the diffraction efficiency curve of the coupling-out grating in the coupling-out region can be changed, thereby realizing the modulation of the light coupling-out intensity to achieve a uniform light output effect.

[0031] The optical solution proposed in the embodiment of the present application realizes the movement and regulation of the peak position of the diffraction efficiency curve of the out-coupling grating by regulating the residual layer 4 in the non-coupling area. This technology can not only improve the out-coupling efficiency, but also provide a new solution for the performance optimization of augmented reality (AR) optical display systems. Through the technical solution provided by this application, the transmission and out-coupling process of light can be accurately controlled, thereby meeting the requirements of AR optical display systems for high efficiency and high uniformity, and can further promote the development and application of AR technology.

[0032] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0034] Figure 1 A schematic diagram of the structure of a diffractive optical structure provided in an embodiment of the present application;

[0035] Figure 2 A schematic diagram of the structure of the outcoupling region provided in an embodiment of the present application;

[0036] Figure 3 One of the outcoupling efficiency curves of the diffractive optical structure provided in Example 1 of the present application;

[0037] Figure 4 The second outcoupling efficiency curve of the diffractive optical structure provided in Example 1 of the present application;

[0038] Figure 5 The third outcoupling efficiency curve of the diffractive optical structure provided in Example 1 of the present application;

[0039] Figure 6 One of the outcoupling efficiency curves of the diffractive optical structure provided in Example 2 of the present application;

[0040] Figure 7 The second outcoupling efficiency curve of the diffractive optical structure provided in Example 2 of the present application;

[0041] Figure 8 This is the third out-coupling efficiency curve of the diffractive optical structure provided in Example 2 of the present application.

[0042] Description of reference numerals:

[0043] 1. Substrate; 2. Incoupling region; 3. Outcoupling region; 4. Residual layer. DETAILED DESCRIPTION

[0044] 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.

[0045] 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.

[0046] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0047] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0048] 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.

[0049] The following is a detailed description of the diffraction optical structure, the method for controlling the diffraction efficiency in the non-coupling zone, and the optical device provided in the embodiments of the present application in conjunction with the accompanying drawings.

[0050] In the diffractive optical structure, the diffractive optical waveguide device (or diffractive optical waveguide plate) is a common form, and the diffractive optical waveguide device will be referred to as an optical waveguide hereinafter.

[0051] The overall optical performance of the waveguide depends mainly on two key factors: coupling efficiency and pupil expansion coupling efficiency. Among the two, the coupling efficiency is maximized to ensure that as much external light as possible can be captured and guided into the waveguide. The regulation mechanism of pupil expansion coupling efficiency shows more complex and changeable characteristics. In contrast, the management of pupil expansion coupling efficiency requires a more refined adjustment strategy based on the specific characteristics of light at different positions in the waveguide and its desired coupling angle.

[0052] by Figure 1 Taking the side view of the diffraction optical structure shown as an example, at the front end of the decoupling zone 3 (the part adjacent to the coupling zone 2), this area is relatively tolerant to the angle of the incident light, and the decoupling efficiency is generally maintained at a low level. This design is mainly to effectively couple out those light rays with a large total reflection angle, so the peak of its efficiency curve naturally falls within a large angle range. As the light gradually propagates from the front end to the rear end along the length direction of the substrate 1, the peak position of the diffraction efficiency curve also changes dynamically, showing a trend of smooth transition from a large angle to a small angle. In view of this feature, the present application proposes a diffraction optical structure design scheme, which aims to optimize the decoupling efficiency of the optical waveguide.

[0053] According to one embodiment of the present application, a diffractive optical structure is provided. Figure 1 and Figure 2The diffractive optical structure comprises a substrate 1 and at least one coupling-in region 2 and at least one coupling-out region 3 arranged on the substrate 1, wherein the coupling-in region 2 is used to couple external light into the substrate 1, and the coupling-out region 3 is used to expand the pupil of the light and couple it out; the coupling-out region 3 is provided with a coupling-out grating having a residual layer 4, and the residual layer 4 has a set thickness variation trend at different positions of the coupling-out grating, so as to regulate the coupling-out intensity of the light; the refractive index of the residual layer 4 is different from that of the substrate 1, and the refractive index difference between the two is △n, 0.1≤△n≤0.8; the coupling-out region 3 is configured to regulate the peak position of the diffraction efficiency curve of the coupling-out grating by the thickness variation trend of the residual layer 4 during the transmission of the light along the length direction of the diffractive optical structure, so as to achieve uniform coupling of the light at different positions of the coupling-out region 3.

[0054] The diffractive optical structure provided in the embodiment of the present application aims to optimize the light outcoupling efficiency through a carefully designed residual layer 4 , thereby achieving uniform outcoupling of light in the outcoupling region 3 .

[0055] The diffractive optical structure provided in the embodiments of the present application is shown in FIG. Figure 1 and Figure 2 , which mainly includes four parts: a substrate 1, a coupling-in region 2, a coupling-out region 3, and a residual layer 4 remaining on the substrate 1 and at least located in the coupling-out region 3.

[0056] The substrate 1 serves as the support of the entire diffractive optical structure, and it carries the settings of other functional areas. The coupling-in area 2 is responsible for coupling external light (such as projection light emitted by an image source) into the substrate 1, and it is the primary channel for light to enter the diffractive optical structure. The coupling-out area 3 is responsible for expanding the pupil of light and coupling it out, and it is the key area for light to leave the diffractive optical structure and enter the human eye.

[0057] It is worth noting that a coupling-out grating is arranged in the coupling-out region 3. Different from the conventional technology, the coupling-out grating of the present application has a key residual layer 4, and the residual layer 4 has a specific thickness variation trend at different positions of the coupling-out grating, which is the key to achieving uniform coupling-out of light.

[0058] In the diffractive optical structure provided in the embodiment of the present application, the residual layer 4 is an important component, which is located on the substrate 1, especially in the outcoupling area 3, and has a decisive influence on the outcoupling efficiency of light.

[0059] The residual layer 4 is made of a material different from the substrate material to ensure that there is a significant refractive index difference between the two. This refractive index difference is the basis for adjusting the peak position of the diffraction efficiency curve of the out-coupling grating by adjusting the thickness of the residual layer 4. Specifically, the difference between the refractive index of the residual layer 4 and the refractive index of the substrate 1 is constrained to be within the range of 0.1 to 0.8. The selection of this range not only ensures the effectiveness of the diffraction efficiency regulation, but also avoids the problem of increased difficulty in regulation or unstable performance due to excessive refractive index difference.

[0060] One of the key characteristics of the residual layer 4 is that its thickness has a specific variation trend at different positions of the outcoupling grating. This thickness variation trend is specially designed to achieve uniform outcoupling of light at different positions in the outcoupling region 3 by changing the peak position of the diffraction efficiency curve of the light during the transmission process of the diffractive optical structure. When the light is transmitted along the length direction of the diffractive optical structure of the present application, the change in the thickness of the residual layer 4 will cause the peak position of the diffraction efficiency curve of the outcoupling grating to move accordingly, thereby achieving fine regulation of the light outcoupling intensity.

[0061] In the present application, the material selection of the residual layer 4 is diverse. For example, the residual layer 4 can be an organic material such as glue, which is realized by spin coating or inkjet. For another example, the residual layer 4 can also be an inorganic material such as titanium oxide, aluminum oxide, silicon oxide, etc., which is prepared by PVD, CVD or ALD. The selection of these materials depends on the specific application scenario and performance requirements to ensure that the residual layer 4 can meet the requirements of optics, mechanics, etc.

[0062] The residual layer 4, as a key part of the diffractive optical structure of the embodiment of the present application, realizes precise control of the light outcoupling efficiency through its thickness variation trend and refractive index difference, and provides strong support for improving the overall optical efficiency of the diffractive optical structure and the uniformity of the outcoupling light intensity.

[0063] Regarding the residual layer 4 mentioned in the present application, it should be noted that it is intentionally retained as a direct product of the process in the manufacturing process of the diffractive optical structure, especially when constructing the outcoupling grating of the outcoupling area 3, and constitutes at least one layer of key material. Specifically, when a outcoupling grating is made on the substrate 1 by using specific technical means such as etching and deposition, a layer of material that is not completely removed will be left on the substrate part of the outcoupling grating due to process conditions or design considerations. This is the so-called residual layer 4.

[0064] In other words, the existence of the residual layer 4 of the present application is by no means accidental. In the present application, the residual layer 4 plays an important role in adjusting the diffraction efficiency curve of the outcoupling grating of the outcoupling region 3. By reasonably designing the thickness of the residual layer 4 in different regions of the outcoupling grating, the outcoupling efficiency and direction of the light in the outcoupling grating can be fine-tuned, thereby achieving a more accurate and flexible outcoupling light control effect.

[0065] The residual layer 4 is a key material layer that is naturally generated and intentionally retained during the process of making the outcoupling region 3. It plays a vital role in the production of the diffractive optical structure and its performance optimization. By managing the thickness of the residual layer 4, the present application is able to significantly improve the ability to regulate light, laying a solid foundation for the advancement and application of augmented reality (AR) optical systems.

[0066] The diffractive optical structure provided in the embodiment of the present application can realize the regulation of the diffraction efficiency curve of the out-coupling grating. Specifically, in the process of light transmission along the length direction of the diffractive optical structure, the thickness variation trend of the residual layer 4 can effectively regulate the peak position of the diffraction efficiency curve of the out-coupling grating. This regulation mechanism allows the out-coupling intensity of light at different positions to be adjusted, thereby avoiding the problem of local over-coupling or under-coupling.

[0067] The diffractive optical structure provided in the embodiment of the present application can realize uniform outcoupling of light. Specifically, by controlling the thickness variation trend of the residual layer 4 and the difference in refractive index between the residual layer 4 and the substrate 1, the diffractive optical structure can realize uniform outcoupling of light at different positions in the outcoupling area. This improves the overall optical efficiency of the diffractive optical structure and improves the visual experience of the optical device.

[0068] The diffractive optical structure provided in the embodiment of the present application is particularly suitable for diffractive waveguide technology in the field of augmented reality (AR). It can significantly improve the efficiency and uniformity of AR optical solutions, and provide strong support for the lightweight, miniaturization and high performance of AR devices.

[0069] The diffraction optical structure provided in the embodiment of the present application realizes uniform outcoupling of light in the outcoupling area 3 through the design of the residual layer 4, and has significant technical effects and broad application prospects.

[0070] In the diffractive optical structure of the embodiment of the present application, a coupling-out grating is arranged in the coupling-out region 3 .

[0071] The outcoupling grating in the outcoupling region 3 may be a one-dimensional grating or a two-dimensional grating.

[0072] In some examples of the present application, the refractive index difference Δn between the residual layer 4 and the substrate 1 is: 0.2≤Δn≤0.5.

[0073] The diffractive optical structure provided in the embodiment of the present application adjusts the movement of the peak position of the grating diffraction efficiency curve by changing the thickness of the residual layer of the grating structure in the non-incoupling area, thereby optimizing the outcoupling efficiency of the outcoupling grating at different positions. The key here is the refractive index difference between the residual layer 4 and the substrate 1, which directly affects the movement and regulation effect of the peak position of the diffraction efficiency curve.

[0074] In this example of the present application, the refractive index difference △n between the residual layer 4 and the substrate 1 is controlled between 0.2 and 0.5. When the refractive index difference △n is within this range, the change in the thickness of the residual layer 4 can more sensitively and stably regulate the peak position of the diffraction efficiency curve.

[0075] When 0.2≤△n≤0.5, a slight change in the thickness of the residual layer 4 can lead to a significant shift in the peak position of the diffraction efficiency curve, which makes the control process both sensitive and stable. By precisely controlling the thickness of the residual layer 4, the out-coupling light of the out-coupling grating at different positions can be optimized, thereby achieving a more uniform light output effect. This is crucial to improving the overall efficiency and user experience of the AR optical solution.

[0076] When the refractive index difference is too small, such as less than 0.1, the change in the thickness of the residual layer 4 does not significantly affect the diffraction efficiency curve; and when the refractive index difference is too large, such as greater than 0.8, the change in the thickness of the residual layer 4 becomes too sensitive, resulting in instability during the control process. Therefore, the selection of the range of 0.2≤△n≤0.5 avoids the occurrence of these extreme situations.

[0077] It should be noted that when the refractive index difference Δn is less than 0.2, the effect of the thickness of the residual layer 4 on the diffraction efficiency curve of the outcoupling grating will be relatively weak. This means that even if the thickness of the residual layer 4 changes significantly, the peak position of the diffraction efficiency curve may only move slightly. In this case, it will become more difficult to control the outcoupling efficiency by adjusting the thickness of the residual layer 4, because the sensitivity of the regulation will be greatly reduced.

[0078] When the refractive index difference Δn is greater than 0.5 but less than 0.8, the change in the thickness of the residual layer 4 may have an overly sensitive effect on the diffraction efficiency curve. This means that even if the thickness of the residual layer 4 changes only slightly, the peak position of the diffraction efficiency curve may move greatly. In this case, the regulation process may become unstable, making it difficult to achieve stable control of the outcoupling efficiency.

[0079] When the refractive index difference Δn is greater than or equal to 0.8, the effect of the change in the thickness of the residual layer 4 on the diffraction efficiency curve may become very sensitive and unstable. In this case, even a slight adjustment to the residual layer 4 may lead to a drastic change in the diffraction efficiency curve, making the regulation process difficult to control. This will seriously affect the performance of the AR optical display system.

[0080] In summary, the range of the refractive index difference △n proposed in this example of the present application, i.e., 0.2≤△n≤0.5, is determined based on the in-depth understanding and optimization requirements of the efficiency curve movement characteristics in the diffraction waveguide technology. This choice not only achieves stable and sensitive regulation of the diffraction efficiency curve, but also optimizes the outcoupling efficiency and avoids the occurrence of extreme situations, thereby improving the overall efficiency of the AR optical solution and the user's visual experience.

[0081] In some examples of the present application, during the transmission of the light along the length direction of the diffraction optical structure, the thickness of the residual layer 4 gradually decreases, so that the peak position of the diffraction efficiency curve of the out-coupling grating gradually moves from a large angle to a small angle along the transmission path of the light.

[0082] As the light is transmitted along the length direction of the diffractive optical structure, the thickness of the residual layer 4 gradually decreases, causing the peak position of the diffraction efficiency curve of the outcoupling grating in the outcoupling region 3 to gradually move from a large angle to a small angle. This regulation process ensures that during the transmission of light in the diffractive optical structure, precise outcoupling regulation can be performed according to the light angle requirements at different positions.

[0083] By adjusting the thickness variation of the residual layer 4 at different positions of the outcoupling grating, the outcoupling efficiency can be controlled. At different stages of light transmission, according to the requirements of the light angle, the outcoupling efficiency is optimized by adjusting the thickness of the residual layer 4, so that the effective outcoupling efficiency is further improved.

[0084] Based on the regulation of the thickness of the residual layer 4, the diffraction efficiency curve of the outcoupling grating can be adaptively adjusted according to the light angle requirements at different positions, thereby achieving a more uniform light output effect. This helps to improve the overall efficiency of the diffractive optical structure, while improving image quality and user visual experience.

[0085] In some examples of the present application, the thickness of the residual layer 4 is RSL, RSL*Δn=C, C is a constant, and 2mm≤C≤60mm.

[0086] The relationship between the thickness RSL of the residual layer 4 and the refractive index difference Δn can be controlled by the C value (between 2 mm and 60 mm). This relationship allows the diffraction efficiency curve of the non-incoupling region, such as the outcoupling grating, to be accurately controlled by fine-tuning the thickness of the residual layer 4 during the manufacturing process.

[0087] When the C value is fixed, as long as the constant C is kept constant during each manufacturing process, a more consistent and stable control effect can be achieved. This helps improve production efficiency and product quality and reduce performance fluctuations caused by inconsistent control.

[0088] Controlling the thickness of the residual layer 4 is crucial to optimizing the overall optical performance of the diffractive optical structure. By adjusting the thickness of the residual layer 4, the peak position of the diffraction efficiency curve of the out-coupling grating can be regulated, thereby optimizing the out-coupling efficiency of light, reducing light loss, and improving image quality and visual experience.

[0089] Different material systems may have different refractive indices, and the design of the C value allows the precise control of the peak position of the diffraction efficiency curve in the non-coupling region under different material systems.

[0090] In the present application, the thickness RSL of the residual layer 4 is inversely proportional to the refractive index difference Δn between the substrate 1 and the residual layer 4 .

[0091] The diffractive optical structure provided in the embodiment of the present application is intended to improve the diffraction efficiency and uniformity of the diffractive optical structure by adjusting the diffraction efficiency of the non-coupling region. On this basis, this example of the present application proposes a key technical innovation point, namely, the inverse relationship between the thickness RSL of the residual layer 4 and the refractive index difference △n between the substrate 1 and the residual layer 4.

[0092] The inverse relationship between the thickness RSL of the residual layer 4 and the refractive index difference Δn indicates that, as the refractive index difference Δn increases, in order to maintain the same diffraction effect, the thickness RSL of the residual layer 4 needs to be reduced accordingly. Conversely, when the refractive index difference Δn decreases, the thickness RSL of the residual layer 4 can be increased accordingly.

[0093] The magnitude of the refractive index difference Δn directly affects the propagation behavior of light between the substrate 1 and the residual layer 4. By adjusting this difference value, the light propagation path and diffraction efficiency can be controlled.

[0094] In order to satisfy this inverse relationship, the material of the residual layer 4 needs to have an adjustable refractive index and be able to achieve a desired thickness through an appropriate process method (such as spin coating, inkjet, PVD, CVD or ALD, etc.).

[0095] According to the design scheme proposed in this example of the present application, by controlling the thickness RSL of the residual layer 4 and the refractive index difference △n, the diffraction efficiency curve of the out-coupling grating can be regulated. This helps to optimize the out-coupling efficiency and make the transmission of light in the diffractive optical structure more efficient and uniform.

[0096] In some examples of the present application, the thickness of the residual layer 4 is RSL, and 10 nm ≤ RSL ≤ 300 nm.

[0097] The thickness RSL of the residual layer 4 is limited to 10 nm to 300 nm. This setting is based on the need to control the diffraction efficiency in the non-coupling area and the consideration of the manufacturing process.

[0098] The change in the thickness of the residual layer 4 will directly affect the diffraction efficiency curve of the outcoupling grating. In the present application, by adjusting the thickness of the residual layer 4 to 10nm-300nm, the peak position of the diffraction efficiency curve can be moved and regulated, thereby optimizing the outcoupling efficiency.

[0099] By limiting the thickness RSL of the residual layer 4 to 10 nm to 300 nm, the diffraction efficiency curve of the non-incoupling region, such as the outcoupling grating, can be regulated. This setting enables the technical solution to flexibly adjust the thickness of the residual layer 4 according to different application scenarios and requirements, thereby optimizing the outcoupling efficiency and improving the efficiency and uniformity of the waveguide.

[0100] By adjusting the thickness range of the residual layer 4, different application scenarios and requirements can be flexibly responded to. For example, in applications requiring higher resolution or wider field of view, better performance can be achieved by adjusting the thickness of the residual layer 4.

[0101] Of course, the thickness of the residual layer 4 may also range from 0 to 500 nm, and this application does not impose any specific limitation on this.

[0102] For example, the thickness of the residual layer 4 is in the range of 0-10 nm. Since the residual layer is very thin, it has little effect on the regulation of the diffraction efficiency curve.

[0103] In the range of 300 nm-500 nm, as the thickness of the residual layer 4 increases, it will have a significant impact on the peak position of the diffraction efficiency curve.

[0104] Achieving precise thickness control on thinner residual layers 4 (approaching 0nm) can be more difficult, as even small thickness variations can have a significant impact on performance. On thicker residual layers, material selection and manufacturing process optimization need to be considered to ensure residual layer stability and reliability.

[0105] The expanded thickness range may provide more options for different application scenarios and requirements. For example, in some specific scenarios, a thicker residual layer may be required to achieve a specific diffraction effect.

[0106] The diffractive optical structure provided in the embodiment of the present application can adjust the outcoupling efficiency of the light at the outcoupling grating by controlling the thickness of the residual layer 4 at different positions of the outcoupling grating, so that the light can be regulated at different positions and at different angles. This design significantly improves the overall optical efficiency of the diffractive optical structure, and enables the light to be coupled out in a more uniform and stable manner, thereby greatly improving the imaging quality and user experience of the augmented reality (AR) optical system.

[0107] In some examples of the present application, the material of the residual layer 4 is glue.

[0108] Glue, as an organic material, usually has a low refractive index.

[0109] Optionally, the glue may be coated on a suitable position of the substrate 1 by spin coating or inkjet, etc., to fabricate a grating structure to form the coupling-in region 2 and / or the coupling-out region 3 .

[0110] Using glue as the material of the residual layer 4 of the present application facilitates adjustment of thickness and uniformity during the manufacturing process to achieve accurate regulation of the diffraction efficiency curve of the outcoupling grating. In addition, the cost of the glue material is relatively low, which helps to reduce the overall manufacturing cost.

[0111] Since the refractive index of the glue is relatively low, the refractive index difference between the glue and the substrate 1 may be more easily controlled within a desired range (eg, 0.1<△n<0.8, or 0.2<△n<0.5), thereby achieving effective light regulation.

[0112] In some examples of the present application, the residual layer 4 is made of an inorganic material, and the inorganic material includes titanium oxide, aluminum oxide, silicon oxide or silicon nitride.

[0113] The inorganic materials proposed in this example of the present application, such as titanium oxide, aluminum oxide, silicon oxide or silicon nitride, mostly have a high refractive index. These inorganic materials can be deposited at a suitable position on the substrate 1 (such as the outcoupling area 3) through processes such as PVD, CVD or ALD.

[0114] The high refractive index of the inorganic material allows the refractive index difference Δn between the residual layer 4 and the substrate 1 to be larger, thereby enhancing the ability to control light. In addition, the inorganic material has better thermal and chemical stability, which helps to maintain the long-term stability of the diffractive optical structure.

[0115] It should be noted that glue generally has a lower refractive index, while inorganic materials generally have a higher refractive index. Therefore, when selecting the material of the residual layer 4, the most suitable material can be selected according to the required refractive index difference range.

[0116] The choice of the material of the residual layer 4 has an important influence on the control effect of the grating diffraction efficiency curve in the non-coupling area. Glue, as a low-cost and easy-to-process material, is suitable for application scenarios that require flexible adjustment of the diffraction efficiency curve; while inorganic materials, with their high refractive index, good stability and performance optimization capabilities, are more suitable for application scenarios with higher requirements for optical performance. In practical applications, the most suitable residual layer material can be selected according to specific needs and manufacturing conditions.

[0117] In some examples of the present application, in the outcoupling region 3, the outcoupling grating includes a front end, a middle part and a rear end; the thickness of the residual layer 4 at the front end of the outcoupling grating is 100nm~300nm, and the peak position of the diffraction efficiency curve of the outcoupling grating is 65°~85°; the thickness of the residual layer 4 in the middle part of the outcoupling grating is 50nm~150nm, and the peak position of the diffraction efficiency curve of the outcoupling grating is 50°~65°; the thickness of the residual layer 4 at the rear end of the outcoupling grating is 5nm~15nm, and the peak position of the diffraction efficiency curve of the outcoupling grating is 30°~50°.

[0118] The diffractive optical structure provided in the embodiment of the present application has a coupling-in region 2 and a coupling-out region 3 arranged on its substrate 1, wherein the coupling-in region 2 is responsible for coupling the external light into the substrate 1, and the coupling-out region 3 is responsible for expanding the pupil of the light and coupling it out of the substrate 1. By adjusting the thickness of the residual layer 4 at different positions at the bottom of the coupling-out region 3, the peak position of the diffraction efficiency curve is regulated.

[0119] In one example, see Figures 3 to 5 The refractive index of the substrate 1 of the diffractive optical structure is 1.9, the refractive index of the residual layer 4 is 2.4, and the refractive index difference Δn between the two is 0.5. This refractive index difference Δn has a direct impact on the performance of the outcoupling grating.

[0120] See also Figure 3 In the initial state, when the thickness of the residual layer is 100 nm, the peak of the diffraction efficiency curve of the out-coupling grating appears at a large angle of 84°. This shows that under the condition of a thicker residual layer, the diffraction effect of light in the out-coupling grating causes the diffraction efficiency peak to be biased towards a large angle.

[0121] See also Figure 4As the light is transmitted toward the rear end in the outcoupling grating, the peak position of the diffraction efficiency curve of the outcoupling grating will change. Specifically, when the thickness of the residual layer 4 decreases, the diffraction efficiency peak will move toward a small angle. This phenomenon shows the close relationship between the thickness of the residual layer 4 and the peak angle of the diffraction efficiency curve.

[0122] In order to further verify this relationship, experimental adjustments were made. When the thickness of the residual layer 4 was reduced to 50 nm, the peak of the diffraction efficiency curve moved to 62°, which shows that by adjusting the thickness of the residual layer 4, I can effectively control the peak position of the efficiency curve of the outcoupling grating.

[0123] See also Figure 5 Finally, the thickness of the residual layer 4 is further reduced to explore its further influence on the peak angle of the diffraction efficiency curve. When the thickness of the residual layer 4 is reduced to only 10nm, the peak angle of the diffraction efficiency curve moves to 36°, further confirming the negative correlation between the thickness of the residual layer 4 and the peak angle of the diffraction efficiency. This relationship is of great significance for optimizing the grating design in the non-coupling region and improving the light transmission efficiency.

[0124] In summary, in the present application, by controlling the thickness of the residual layer 4, the peak position of the diffraction efficiency curve of the non-coupling region grating can be effectively adjusted to meet the needs of different application scenarios.

[0125] In another example, see Figures 6 to 8 The refractive index of the substrate 1 of the diffractive optical structure is 1.7, the refractive index of the residual layer 4 is 1.9, and the refractive index difference Δn between the two is 0.2. This refractive index difference Δn has a direct impact on the performance of the outcoupling grating.

[0126] See also Figure 6 When the thickness of the residual layer 4 is 300 nm, the peak of the diffraction efficiency curve of the outcoupling grating appears at a large angle position of 66°.

[0127] See also Figure 7 As the light is transmitted from the front end to the rear end of the outcoupling grating, the peak position of the efficiency curve of the outcoupling grating will move. Specifically, the diffraction efficiency peak will move toward a small angle direction as the thickness of the residual layer 4 decreases.

[0128] In order to more intuitively demonstrate this change process, further experimental adjustments were made. When the thickness of the residual layer 4 was reduced to 150nm, the peak of the diffraction efficiency curve of the outcoupling grating moved to a position of about 50°. This result further strengthens the negative correlation between the thickness of the residual layer 4 and the peak angle of the diffraction efficiency curve.

[0129] See also Figure 8 When the thickness of the residual layer 4 is further reduced to only 10 nm, the peak angle of the efficiency curve of the outcoupling grating has moved to a position less than 30°. This confirms the ability of the thickness of the residual layer 4 to regulate the peak position of the diffraction efficiency curve.

[0130] In summary, by adjusting the thickness of the residual layer 4, the peak position of the out-coupling grating efficiency curve in the out-coupling region 3 can be flexibly adjusted, thereby meeting the diverse demands on light transmission efficiency in practical applications.

[0131] In some examples of the present application, the diffractive optical structure also includes a turning zone, which is arranged on the substrate 1 and located between the optical paths of the coupling-in zone 2 and the coupling-out zone 3, and the residual layer 4 can extend from the coupling-out zone 3 to at least part of the turning zone.

[0132] In this example of the present application, the diffractive optical structure not only includes the coupling-in region 2 and the coupling-out region 3, but also adds a turning region ( Figure 1 Specifically, this transition zone is disposed on the substrate 1 and is located between the optical paths of the coupling-in zone 2 and the coupling-out zone 3. More uniquely, the design of the residual layer 4 is also extended in this example, which not only covers the bottom of the coupling-out zone 3, but also further extends to the bottom of the transition zone.

[0133] The introduction of the turning zone provides a more flexible and diverse path for the transmission of light in the diffractive optical structure. By designing the shape and size of the turning zone, the direction of light transmission can be precisely controlled, so that the light can enter the outcoupling zone 3 at the expected angle and direction, thereby further improving the performance and efficiency of the optical system.

[0134] By adjusting the thickness and refractive index and other parameters of the residual layer 4 at the bottom of the turning zone, the light can be further regulated and optimized during the transmission process in the turning zone, thereby further improving the overall optical performance.

[0135] According to another embodiment of the present application, a method for controlling the diffraction efficiency of a non-coupling region is provided for use in a diffractive optical structure, see Figure 1 The diffractive optical structure comprises a substrate 1 and at least one coupling-in region 2 and at least one coupling-out region 3 disposed on the substrate 1, wherein the coupling-out region 3 comprises a coupling-out grating having a residual layer 4, and the residual layer 4 has a different refractive index from the substrate 1, and the difference in refractive index between the two is △n, 0.1≤△n≤0.8;

[0136] The diffraction efficiency control method includes the following steps S100 to S300:

[0137] Step S100, in the outcoupling area 3, according to the light transmission path and the required outcoupling angle, determining the thickness variation trend of the residual layer 4 at each position of the outcoupling grating, so as to adjust the peak position of the diffraction efficiency curve of the outcoupling grating;

[0138] Step S200, coupling external light into the substrate 1 through the coupling-in region 2, and causing the light to be totally reflected in the substrate 1 and transmitted to the coupling-out region 3;

[0139] Step S300, regulating the peak position of the diffraction efficiency curve of the out-coupling grating through the residual layer 4, so that when the light is transmitted along the length direction of the diffraction optical structure, the peak value of the diffraction efficiency curve can change according to a predetermined trend, thereby being evenly coupled out at different positions of the out-coupling area 3.

[0140] According to the above step S100, this step is the core preprocessing stage of the control method of the present application. It requires first clarifying the transmission path of the light in the diffractive optical structure and the light coupling angle required at each position. Based on this information, the ideal thickness variation trend of the residual layer 4 at different positions of the coupling grating is calculated.

[0141] According to the above step S200, this step is the actual transmission process of light. The coupling-in region 2 allows external light to enter the substrate 1. The light is transmitted inside the substrate 1 by total reflection, which minimizes the loss of light and effectively guides the light to the coupling-out region 3. The realization of this step depends on the optical properties of the substrate material and the structural design of the coupling-in region.

[0142] According to the above step S300, in this step, the design and manufacture of the residual layer 4 enables the peak position of the diffraction efficiency curve of the outcoupling grating to change according to the predetermined trend determined in step S100. This change ensures that the light can be uniformly outcoupled at different positions of the outcoupling area 3 during the transmission along the length direction of the diffractive optical structure. This uniform outcoupling is crucial to improving the overall efficiency and performance of the diffractive optical structure.

[0143] As the light continues to propagate in the outcoupling region 3, the peak position of the diffraction efficiency curve of the outcoupling grating will change accordingly due to the change in the thickness of the residual layer 4. This change ensures that the light can be coupled out at appropriate angles at different positions, thereby achieving efficient and uniform light output of the entire diffractive optical structure.

[0144] By implementing the above steps S100 to S300, the method for regulating the diffraction efficiency of the non-incoupling zone provided by the present application achieves the following technical effects:

[0145] (1) Improved diffraction efficiency: By precisely controlling the thickness variation trend of the residual layer 4, the control method of the present application can control the peak position of the diffraction efficiency curve of the out-coupling grating, thereby achieving uniform out-coupling of light in the out-coupling region 3 and improving the diffraction efficiency.

[0146] (2) Enhanced performance of the optical structure: The control method of the present application optimizes the transmission path and decoupling process of light in the diffractive optical structure, reduces light loss, and thus enhances the overall performance of the optical structure.

[0147] In summary, the method for regulating the diffraction efficiency of the non-coupling zone provided in the present application achieves efficient and uniform outcoupling of light in the diffraction optical structure by precisely controlling the thickness and refractive index difference of the residual layer, thereby improving the overall performance and efficiency of the optical structure.

[0148] According to another embodiment of the present application, an optical device is provided, which includes an image source and the diffractive optical structure as described above, wherein the light emitted by the image source can be incident on the coupling-in region on the diffractive optical structure.

[0149] The image source is, for example, a projection light machine.

[0150] The diffractive optical structure is, for example, a diffractive optical waveguide.

[0151] The diffractive optical structure may be provided in two numbers: one diffractive optical structure corresponds to the left eye of the user, and the other diffractive optical structure corresponds to the right eye of the user.

[0152] The optical device provided in the embodiment of the present application is, for example, an AR optical display device. Further, the AR optical display device is, for example, AR smart glasses or an AR smart helmet.

[0153] The specific implementation of the optical device of the embodiment of the present application can refer to the above-mentioned embodiments of the diffractive optical structure, so it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0154] 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.

[0155] 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 diffractive optical structure, characterized in that: It comprises a substrate (1) and: At least one coupling region (2) for coupling external light into the substrate (1); At least one outcoupling region (3) for dilating the pupil of the light and outcoupling the light; The outcoupling region (3) is provided with an outcoupling grating having a residual layer (4), and the residual layer (4) has a set thickness variation trend at different positions of the outcoupling grating, so as to adjust the outcoupling intensity of the light; The residual layer (4) and the substrate (1) have different refractive indices, and the difference in refractive index between the two is Δn, 0.1≤Δn≤0.8; The decoupling region (3) is configured to, during the transmission of light along the length direction of the diffractive optical structure, regulate the peak position of the diffraction efficiency curve of the decoupling grating by means of the thickness variation trend of the residual layer (4), so as to achieve uniform decoupling of light at different positions of the decoupling region (3).

2. The diffractive optical structure according to claim 1, characterized in that: The refractive index difference Δn between the residual layer (4) and the substrate (1) is: 0.2≤Δn≤0.

5.

3. The diffractive optical structure according to claim 1, characterized in that: During the transmission of the light along the length direction of the diffractive optical structure, the thickness of the residual layer (4) gradually decreases, so that the peak position of the diffraction efficiency curve of the outcoupling grating gradually moves from a large angle to a small angle along the transmission path of the light.

4. The diffractive optical structure according to claim 3, characterized in that: The thickness of the residual layer (4) is RSL, RSL*Δn=C, C is a constant, and 2mm≤C≤60mm.

5. The diffractive optical structure according to claim 4, characterized in that: The thickness of the residual layer (4) is RSL, and 10nm≤RSL≤300nm.

6. The diffractive optical structure according to claim 1, characterized in that: The material of the residual layer (4) is glue.

7. The diffractive optical structure according to claim 1, characterized in that: The residual layer (4) is made of an inorganic material, which includes titanium oxide, aluminum oxide, silicon oxide or silicon nitride.

8. The diffractive optical structure according to claim 2, characterized in that: In the outcoupling region (3), the outcoupling grating comprises a front end, a middle part and a rear end; The thickness of the residual layer (4) at the front end of the out-coupling grating is 100 nm to 300 nm, and the peak position of the diffraction efficiency curve of the out-coupling grating is 65° to 85°; The thickness of the residual layer (4) in the middle of the outcoupling grating is 50nm-150nm, and the peak position of the diffraction efficiency curve of the outcoupling grating is 50°-65°; The thickness of the residual layer (4) at the rear end of the out-coupling grating is 5nm-15nm, and the peak position of the diffraction efficiency curve of the out-coupling grating is between 30° and 50°.

9. The diffractive optical structure according to any one of claims 1 to 8, characterized in that: The diffractive optical structure further comprises a turning zone, which is arranged on the substrate (1) and located between the optical paths of the coupling-in zone (2) and the coupling-out zone (3), and the residual layer (4) can extend from the coupling-out zone (3) to at least a portion of the turning zone.

10. A method for controlling the diffraction efficiency of a non-coupling region, used in a diffractive optical structure, characterized in that: The diffractive optical structure comprises a substrate (1) and at least one coupling-in region (2) and at least one coupling-out region (3) arranged on the substrate (1), wherein the coupling-out region (3) comprises a coupling-out grating having a residual layer (4), and the residual layer (4) and the substrate (1) have different refractive indices, and the difference in refractive index between the two is Δn, 0.1≤Δn≤0.8; The method for controlling the diffraction efficiency includes: In the outcoupling region (3), according to the light transmission path and the required outcoupling angle, the thickness variation trend of the residual layer (4) at each position of the outcoupling grating is determined to adjust the peak position of the diffraction efficiency curve of the outcoupling grating; The external light is coupled into the substrate (1) through the coupling-in region (2), and the light is totally reflected in the substrate (1) and transmitted to the coupling-out region (3); The peak position of the diffraction efficiency curve of the out-coupling grating is regulated by the residual layer (4), so that during the transmission of light along the length direction of the diffraction optical structure, the peak value of the diffraction efficiency curve can change according to a predetermined trend, thereby achieving uniform out-coupling at different positions of the out-coupling region (3).

11. An optical device, characterized in that: include: Image source; and According to the diffractive optical structure as claimed in any one of claims 1 to 9, the light emitted by the image source can be incident on the coupling-in region (2).

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