Low-rainbow-pattern waveguide sheet and AR lens

Abstract

The utility model relates to a low rainbow pattern waveguide sheet and an AR lens, the low rainbow pattern waveguide sheet comprises a waveguide substrate and a grating structure arranged on the surface of the waveguide substrate, the refractive index of the waveguide substrate is more than 1.8, the refractive index of the grating structure is 1.5-2.0, the grating period of the grating structure is within 320nm, and the refractive index of the grating structure is more than 1.8. Light diffracted by the grating structure is totally reflected in the waveguide substrate and is coupled out along a direction forming an included angle with the surface of the waveguide substrate; the AR lens comprises the waveguide sheet and a plurality of protective films made of an optical resin material. According to the utility model, by optimizing the design of the waveguide sheet, the rainbow pattern phenomenon is obviously reduced, the light and thin design is realized, and the weight of the AR lens is reduced, so that the wearing comfort and portability are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of near-eye display devices, and in particular to a low-rainbow ripple waveguide sheet and an AR lens. Background Art

[0002] In recent years, AR glasses have received extensive attention because they can seamlessly integrate virtual information with the real world. Among many AR lens technical solutions, the surface relief grating technology is considered to be the most promising solution for realizing consumer-grade AR glasses due to its excellent performance. To provide a better wearing experience, AR lenses must have the characteristics of being thin and light. For this reason, the concept of resin lenses has been proposed in recent years to solve the problem of thinness and lightness. However, resin lenses still face major challenges in terms of thermal stability and process reliability, which limits their large-scale application in the market. In contrast, AR glasses using high-refractive-index glass or other solid substrate materials show better performance in process stability and have obvious advantages in mass production.

[0003] A Chinese patent with the publication number CN118409384A applied by the applicant recently discloses a thin and light waveguide sheet lens, its preparation method and application. The thin and light waveguide sheet lens includes a waveguide sheet composed of a wide-bandgap semiconductor material and a protective film composed of an optical resin material. At least one surface of the waveguide sheet has a grating structure. The protective film is disposed on the surface of the waveguide sheet and is embedded in the grating gaps of the grating structure, and the outer surfaces of the protective film and the grating structure are approximately in the same plane and / or the protective film covers the outer surface of the grating structure. The above waveguide sheet lens replaces the high-refractive-index glass waveguide sheet with a refractive index of 1.7-1.9 with a wide-bandgap semiconductor material waveguide sheet, and replaces the cover glass with an optical resin material protective film. While protecting the waveguide sheet on both sides, reducing the overall thickness of the waveguide sheet lens, and improving the optical performance, functions such as hardening, scratch resistance, anti-fogging, anti-slip, anti-fouling, and high transparency can be compounded.

[0004] To improve the visual experience, it is crucial to effectively eliminate rainbow ripples. The rainbow ripple phenomenon occurs when ambient light diffracts and disperses through the grating structure, resulting in colored bright lines in front of the eyes of the glasses wearer, which undoubtedly affects the visual comfort of the user. Traditional myopia and hyperopia glasses usually do not have the problem of rainbow ripples. Therefore, in order for the above thin and light waveguide sheet lens to gain the favor of consumers, solving the rainbow ripple problem has become one of the key challenges. Based on this, we can design the waveguide sheet structure according to specific requirements. On the basis of ensuring the closure of the grating vector and meeting other product requirements, how to reduce the influence of rainbow ripples is the technical problem that we urgently need to solve at present. Summary of the Utility Model

[0005] In view of the deficiencies of the prior art, the first object of the present invention is to provide a low-rainbow waveguide sheet, which has the advantage of reducing rainbow patterns.

[0006] The second object of the present invention is to provide an AR lens, which has the advantages of reducing rainbow patterns and being thin and light.

[0007] To achieve the above first object, the present invention provides the following technical solutions:

[0008] A low-rainbow waveguide sheet includes a waveguide substrate and a grating structure disposed on the surface of the waveguide substrate. The refractive index of the waveguide substrate is above 1.8, the refractive index of the grating structure is 1.5 - 2.0, and the grating period of the grating structure is within 320 nm, so that the light diffracted by the grating structure undergoes total internal reflection in the waveguide substrate and is coupled out along a direction forming an angle with the surface of the waveguide substrate.

[0009] By adopting the above technical solution, the grating structure can be a volume holographic grating based on liquid crystal material or a surface relief grating. Similarly, it can also be a one-dimensional grating and / or a two-dimensional grating. As long as the refractive indices of the waveguide substrate and the grating structure are controlled, so that after the light is diffracted by the grating structure with a grating period within 320 nm, total internal reflection occurs in the waveguide layer. Since the grating periods in the turning region and the coupling-out region are relatively small, for the ambient light passing through these grating regions, there are relatively few directions of light that can satisfy the diffraction condition. For the ambient light that can undergo diffraction, after passing through the coupling-in region, the turning region and the coupling-out region, the angle between the finally coupled-out light and the surface of the waveguide substrate is within 40°. The outgoing light is difficult for the human eye to capture, so the rainbow patterns can be completely eliminated. Therefore, the low-rainbow waveguide sheet of the present utility model can effectively reduce the diffraction and dispersion phenomena caused by the grating structure, thereby reducing the generation of rainbow patterns. Specifically, by optimizing parameters such as the period, height, and duty cycle of the grating, the propagation of light in the waveguide sheet can be made more uniform, and the separation of light with different wavelengths can be reduced, so as to achieve the purpose of reducing rainbow patterns.

[0010] The present utility model is further configured such that the waveguide substrate and the grating structure are each independently composed of quartz, glass, ceramic, titanium dioxide, or silicon nitride.

[0011] By adopting the above technical solution, the material selection of the waveguide substrate and the grating structure will affect the optical performance of the waveguide sheet, and they can be combined according to the actual situation.

[0012] The present utility model is further configured such that the thickness of the waveguide substrate is 0.3 - 1.2 mm.

[0013] By adopting the above technical solutions, it is ensured that while maintaining sufficient strength, the waveguide sheet realizes a thin and light design. The thinner waveguide substrate helps reduce the propagation loss of light inside the waveguide sheet and at the same time reduces the overall weight, making the AR lens more comfortable and portable.

[0014] The present utility model is further configured as follows: The grating structure includes an input grating, a turning grating, and an output grating, and the waveguide substrate includes an input area, a turning area, and an output area; The input grating is disposed on the input area, and the input grating is used to couple a light beam into the waveguide substrate and propagate the light beam inside the waveguide substrate; The turning grating is disposed on the turning area, and the turning grating is used to receive the light beam propagated by the input grating and guide the light beam to the output area; The output grating is disposed on the output area, and the output grating is used to receive the light beam propagated by the turning grating and couple the light beam out of the waveguide substrate.

[0015] By adopting the above technical solutions, under the condition of satisfying the grating vector closure and other product requirements, the size of the grating period in the turning area is minimized as much as possible to achieve the purpose of suppressing rainbow fringes.

[0016] The present utility model is further configured as follows: The input grating, the turning grating, and the output grating are each independently configured as a combined grating of one or several of an inclined grating, a trapezoidal grating, a blazed grating, a curved grating, and a rectangular grating.

[0017] By adopting the above technical solutions, the structural design of the grating can be further optimized to adapt to the propagation requirements of light of different wavelengths, thereby improving the optical efficiency of the waveguide sheet lens and reducing the rainbow fringe phenomenon; For example, the inclined grating can effectively control the incident angle of light, the trapezoidal grating and the blazed grating can enhance the selectivity of the grating for light of a specific wavelength, while the curved grating and the rectangular grating can improve the propagation path of light in the waveguide sheet and reduce unnecessary diffraction and dispersion.

[0018] The present utility model is further configured as follows: The input grating is configured as a one-dimensional inclined grating or a one-dimensional blazed grating, the grating period of the input grating is 298 - 309 nm, the included angle between the grating vector and the length direction of the waveguide substrate is -70 - -63°, the grating height is 140 - 220 nm, the duty cycle is 35 - 58%, and the inclination angle or the blaze angle is 29 - 32°.

[0019] By adopting the above technical solutions, it is beneficial to reduce rainbow fringes.

[0020] The present utility model is further configured as follows: The turning grating is configured as a one-dimensional rectangular grating, the grating period of the turning grating is 230-244 nm, the included angle between the grating vector and the length direction of the waveguide substrate is 60-67°, the grating height is 41-106 nm, and the duty cycle is 42-58%.

[0021] By adopting the above technical solution, it is beneficial to reduce rainbow patterns.

[0022] The present utility model is further configured as follows: The output grating is configured as a one-dimensional rectangular grating, the grating period of the output grating is 298-309 nm, the included angle between the grating vector and the length direction of the waveguide substrate is 10-17°, the grating height is 56-100 nm, and the duty cycle is 31-62%.

[0023] By adopting the above technical solution, it is beneficial to reduce rainbow patterns.

[0024] The present utility model is further configured as follows: The turning grating and the output grating are each independently divided into a plurality of grating partitions along the light transmission direction, and the depth and duty cycle of the plurality of grating partitions vary in a gradient manner along the grating vector direction.

[0025] By adopting the above technical solution, on the premise of keeping the grating period and the grating vector direction of the turning grating and the output grating unchanged, the uniformity and efficiency of light output are further improved by means of grating partitioning, so as to achieve better imaging quality. The selection of the grating structure and the partitioning method will not affect the rainbow pattern phenomenon.

[0026] To achieve the second above-mentioned object, the present invention provides the following technical solution:

[0027] An AR lens, comprising the above-mentioned waveguide sheet and a plurality of protective films made of optical resin materials, wherein one of the protective films is disposed on the surface of the waveguide sheet and embedded in the grating gaps of the grating structure, and the one protective film and the outer surface of the grating structure are approximately in the same plane and / or the one protective film covers the outer surface of the grating structure.

[0028] By adopting the above technical solution, in order to enable the AR lens to obtain better optical effects and play a sufficient protective role, other functional films such as antireflection films, waterproof films, antifogging films, etc. can also be deposited on the surfaces of the waveguide layer and the protective layer. The thicknesses of these functional materials are all at the nanometer level and have almost no influence on the overall thickness of the lens. The above method can obtain an extremely thin and light AR lens. Among them, for a waveguide sheet with a thickness of 0.5 mm, the total thickness of the AR lens does not exceed 0.7 mm.

[0029] In summary, the beneficial technical effects of the present utility model are as follows:

[0030] 1. By optimizing the design of the waveguide sheet, the rainbow pattern phenomenon is significantly reduced, the image quality of the display device is improved, and users can obtain a clearer and more comfortable visual experience when using the augmented reality (AR) device;

[0031] 2. By selecting appropriate materials and structural designs, the waveguide sheet of the present utility model achieves a thin and light design while maintaining high optical performance, reduces the weight of the AR lens, and thus improves the wearing comfort and portability;

[0032] 3. The waveguide sheet of the present utility model effectively reduces the propagation loss of light inside the waveguide sheet and improves the optical efficiency by precisely controlling the parameters of the grating structure, such as the period, height, and duty cycle, and by using different types of grating combinations;

[0033] 4. The design of the waveguide sheet of the present utility model also considers the protection requirements in practical applications. By setting a protective film on the surface of the waveguide sheet, not only the durability of the waveguide sheet is enhanced, but also the performance of the AR lens is further improved by coating functional films, such as an antireflection film, a waterproof film, and an antifogging film;

[0034] 5. The design of the waveguide sheet of the present utility model not only meets the optical performance requirements, but also considers the manufacturing cost and process feasibility, making the technical solution highly competitive in the market and having good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of the waveguide sheet of Embodiment 1 of the present utility model.

[0036] Figure 2 is a schematic diagram of the connection relationship between the waveguide substrate and the grating structure of the present utility model.

[0037] Figure 3 is a schematic structural diagram of the waveguide sheet of Embodiment 2 of the present utility model.

[0038] Figure 4 is a schematic structural diagram of the waveguide sheet of Embodiment 3 of the present utility model.

[0039] Figure 5 is a schematic structural diagram of the AR lens of Embodiment 4 of the present utility model.

[0040] Figure 6 is a k-vector distribution diagram of the outgoing light of the ambient light of Embodiment 4 of the present utility model after passing through the turning grating.

[0041] Figure 7 is a k-vector distribution diagram of the outgoing light of the ambient light of Embodiment 4 of the present utility model after passing through the outcoupling grating.

[0042] In the figure, 1 is the waveguide substrate; 2 is the grating structure; 21 is the input grating; 22 is the turning grating; 23 is the output grating; 3 is the protective film. Detailed implementation mode

[0043] In order to make the technical means, creative features, achieved purposes and functions realized by the present utility model clearer and easier to understand, the present utility model will be further described below in conjunction with the accompanying drawings and specific implementation modes.

[0044] Example 1: Refer to Figure 1 , a low-rainbow waveguide sheet disclosed by the present utility model, includes a waveguide substrate 1 and a grating structure 2 disposed on the surface of the waveguide substrate 1. Among them, by optimizing the design of the waveguide sheet, the light diffracted by the grating structure 2 undergoes total internal reflection in the waveguide substrate 1 and is coupled out along a direction forming an angle with the surface of the waveguide substrate 1, significantly reducing the rainbow phenomenon.

[0045] The waveguide substrate 1 and the grating structure 2 are integrally formed and composed of a high-refractive-index glass with a refractive index of 1.9. The thickness of the waveguide substrate 1 is 0.5 mm. Thus, in cooperation with the protective layer structure with a refractive index of 1.5, it can support the coupling out of a virtual image with a wavelength λ of 532 nm and a 28° FOV.

[0046] Among them, the waveguide substrate 1 includes an input region, a turning region, and an output region. The light transmission path should satisfy the grating vector closure relationship, that is, the grating vectors of the input region, the turning region, and the output region can form a closed triangle to ensure that the light beam entering the input region can be coupled out from the output region at the same angle.

[0047] At the same time, the grating structure 2 includes an input grating 21, a turning grating 22, and an output grating 23. The input grating 21 is disposed on the input region, and the input grating 21 is used to couple the light beam into the waveguide substrate 1 and propagate the light beam in the waveguide substrate 1. The turning grating 22 is disposed on the turning region, and the turning grating 22 is used to receive the light beam propagated by the input grating 21 and guide the light beam to the output region. The output grating 23 is disposed on the output region, and the output grating 23 is used to receive the light beam propagated by the turning grating 22 and couple the light beam out of the waveguide substrate 1.

[0048] Refer to Figure 2 , preferably, the input grating 21 is set as a one-dimensional inclined grating. The grating period P of the input grating 21 is 309 nm, the angle between the grating vector G and the length direction of the waveguide substrate 1 is -70°, the grating height H is 140 nm, the duty cycle is 35%, and the inclination angle α is 32°.

[0049] The turning grating 22 is set as a one-dimensional rectangular grating. The grating period P of the turning grating 22 is 244 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 60°, the grating height H is 106 nm, and the duty cycle is 58%.

[0050] The output grating 23 is set as a one-dimensional rectangular grating. The grating period P of the output grating 23 is 309 nm, the included angle between the grating vector G and the length direction of the waveguide substrate 1 is 10°, the grating height H is 67 nm, and the duty cycle is 42%.

[0051] Example 2: Refer to Figure 3 , a low-rainbow waveguide sheet disclosed by the present utility model. The difference from Example 1 is that the turning grating 22 and the output grating 23 are each independently divided into a plurality of grating partitions along the light transmission direction, and the depths and duty cycles of the plurality of grating partitions vary in a gradient manner along the grating vector direction. On the premise of ensuring that the grating periods and grating vector directions of the turning grating 22 and the output grating 23 remain unchanged, the uniformity and efficiency of light output are further improved through the grating partition method, so as to achieve better imaging quality. The selection of the grating structure 2 and the selection of the partition method will not affect the rainbow phenomenon.

[0052] Preferably, the turning grating 22 is divided into 5 grating partitions. Along the light transmission direction, the grating heights H of the turning grating 22 are 41, 84, 74, 106, 100 nm in sequence, and the duty cycles are 49, 48, 58, 54, 42% in sequence.

[0053] The output grating 23 is divided into 6 grating partitions. The grating heights H of the output grating 23 are 76, 82, 68, 79, 80, 100 nm in sequence, and the duty cycles are 31, 46, 48, 50, 49, 62% in sequence.

[0054] Example 3: Refer to Figure 4 , a low-rainbow waveguide sheet disclosed by the present utility model. The difference from Example 1 is that the waveguide substrate 1 and the grating structure 2 are integrally formed and composed of a high-refractive-index glass with a refractive index of 2.0. The thickness of the waveguide substrate 1 is 0.5 mm. Thus, in cooperation with the protective layer structure with a refractive index of 1.45, it can support the output of a virtual image with a wavelength λ of 525 nm and a 32° FOV.

[0055] Preferably, the input grating 21 is set as a one-dimensional blazed grating. The grating period P of the input grating 21 is 298 nm, the included angle between the grating vector G and the length direction of the waveguide substrate 1 is -63°, the grating height H is 220 nm, the duty cycle is 58%, and the blaze angle α is 29°.

[0056] The turning grating 22 is set as a one-dimensional rectangular grating. The grating period P of the turning grating 22 is 230 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 67°, the grating height H is 89 nm, and the duty cycle is 46%.

[0057] The output grating 23 is set as a one-dimensional rectangular grating. The grating period P of the output grating 23 is 298 nm, the included angle between the grating vector G and the length direction of the waveguide substrate 1 is 17°, the grating height H is 56 nm, and the duty cycle is 38%.

[0058] Example 4: Refer to Figure 5 , an AR lens disclosed by the present utility model. The difference from Example 1 lies in that it includes the waveguide sheet of Example 1 and a pair of protective films 3 made of optical resin material. One of the protective films 3 is disposed on the surface of the waveguide sheet and embedded in the grating gap of the grating structure 2, and one of the protective films 3 covers the outer surface of the grating structure 2. Among them, the protective layer obtained by impregnation or spin coating has an effect of filling inside the grating, which will reduce the diffraction efficiency of light. Even if the diffracted ambient light can enter the human eye, the intensity will be relatively low, thus not affecting the visual experience of the human eye.

[0059] Since the grating periods in the turning area and the output area are relatively small, after the ambient light passes through these grating areas, there are relatively few light directions that can meet the diffraction conditions. For the ambient light that can undergo diffraction, the outgoing light rays after passing through the grating form an included angle within 40° with the surface of the waveguide substrate 1 and are difficult to be captured by the human eye. Therefore, rainbow patterns can be completely eliminated. Refer to Figure 6 and Figure 7 , which respectively show the k-vector distribution of the outgoing light rays after the ambient light passes through the gratings in the turning area and the output area of the waveguide sheet. The period of the turning grating 22 is relatively small, and only a very small part of the blue light can meet the diffraction conditions. However, due to a certain distance between the turning area and the output area, the light rays cannot propagate to the human eye after passing through the diffraction of the turning grating 22, so that the human eye cannot observe the rainbow pattern phenomenon. The period of the output area is relatively large, and more light rays can meet the diffraction conditions. However, these light rays have relatively large angles and are also difficult to be captured by the human eye.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit. Although the present utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present utility model can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present utility model, and they should all be covered within the scope of the claims of the present utility model.

Claims

1. A low rainbow ripple waveguide, characterized in that: The invention comprises a waveguide substrate (1) and a grating structure (2) arranged on the surface of the waveguide substrate (1), wherein the refractive index of the waveguide substrate (1) is greater than 1.8, the refractive index of the grating structure (2) is between 1.5 and 2.0, and the grating period of the grating structure (2) is within 320 nm, so that the light diffracted by the grating structure (2) is totally reflected in the waveguide substrate (1) and coupled out along a direction forming an angle with the surface of the waveguide substrate (1).

2. A low rainbow ripple waveguide according to claim 1, characterized in that: The waveguide substrate (1) and the grating structure (2) are each independently composed of one of quartz, glass, ceramic, titanium dioxide and silicon nitride.

3. The low rainbow ripple waveguide according to claim 1, characterized in that: The thickness of the waveguide substrate (1) is 0.3-1.2 mm.

4. The low rainbow ripple waveguide according to claim 1, characterized in that: The grating structure (2) comprises an in-coupling grating (21), a turning grating (22) and an out-coupling grating (23); and the waveguide substrate (1) comprises an in-coupling region, a turning region and an out-coupling region; The coupling-in grating (21) is arranged on the coupling-in region, and the coupling-in grating (21) is used to couple the light beam into the waveguide substrate (1) and propagate the light beam in the waveguide substrate (1); The turning grating (22) is arranged on the turning region, and the turning grating (22) is used to receive the light beam propagated by the coupling-in grating (21) and guide the light beam to the coupling-out region; The outcoupling grating (23) is arranged on the outcoupling region, and the outcoupling grating (23) is used to receive the light beam propagated by the turning grating (22) and couple the light beam out of the waveguide substrate (1).

5. The low rainbow ripple waveguide according to claim 4, characterized in that: The coupling-in grating (21), the turning grating (22) and the coupling-out grating (23) are independently configured as a grating selected from the group consisting of a tilted grating, a trapezoidal grating, a blazed grating, a curved grating and a rectangular grating, or a combination of the two.

6. The low rainbow ripple waveguide according to claim 4, characterized in that: The coupling-in grating (21) is configured as a one-dimensional tilted grating or a one-dimensional blazed grating, the grating period of the coupling-in grating (21) is 298-309 nm, the angle between the grating vector and the length direction of the waveguide substrate (1) is -70--63°, the grating height is 140-220 nm, the duty cycle is 35-58%, and the tilt angle or blaze angle is 29-32°.

7. The low rainbow ripple waveguide according to claim 4, characterized in that: The turning grating (22) is configured as a one-dimensional rectangular grating, the grating period of the turning grating (22) is 230-244 nm, the angle between the grating vector and the length direction of the waveguide substrate (1) is 60-67°, the grating height is 41-106 nm, and the duty cycle is 42-58%.

8. The low rainbow ripple waveguide according to claim 4, characterized in that: The outcoupling grating (23) is set as a one-dimensional rectangular grating, the grating period of the outcoupling grating (23) is 298-309 nm, the angle between the grating vector and the length direction of the waveguide substrate (1) is 10-17°, the grating height is 56-100 nm, and the duty cycle is 31-62%.

9. The low rainbow ripple waveguide according to claim 4, characterized in that: The turning grating (22) and the coupling-out grating (23) are each independently divided into a plurality of grating partitions along the light transmission direction, and the depths and duty ratios of the plurality of grating partitions vary gradiently along the grating vector direction.

10. An AR lens, characterized in that: It comprises a waveguide plate according to any one of claims 1 to 9, and a plurality of protective films (3) made of an optical resin material, wherein one of the protective films (3) is arranged on the surface of the waveguide plate and embedded in the grating gap of the grating structure (2), and the outer surface of the one of the protective films (3) and the grating structure (2) are approximately in the same plane, and / or the one of the protective films (3) covers the outer surface of the grating structure (2).

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