Glass-plastic mixed optical waveguide lens

Abstract

The utility model relates to a glass-plastic mixed optical waveguide lens, which comprises a waveguide substrate with a diffraction grating structure and plasticized film layers symmetrically arranged on two sides of the waveguide substrate, the refractive index of the waveguide substrate is 1.5-2.0, the grating period of the diffraction grating structure is 200-450 nm, the refractive index of the plasticized film layers is 1.2-1.8, and the refractive index of the plasticized film layers is 1.5-2.0. The optical transmission path of the optical waveguide lens passes through the waveguide substrate, the diffraction grating structure and the at least one plasticized film layer so as to be matched with an optical machine within the FOV range of 20-50 degrees. The utility model has the advantages of light weight and good optical performance, and can be upwards compatible with optical machines in a multi-FOV range.

Description

Technical Field

[0001] The utility model relates to the technical field of diffractive optical waveguides, in particular to a glass-plastic hybrid optical waveguide lens. Background Art

[0002] A diffractive optical waveguide is an optical element that uses a diffraction grating structure to guide light waves along a specific path. In applications such as virtual reality (VR), augmented reality (AR), and mixed reality (MR), optical waveguide lenses are widely used to achieve lightweight and high-resolution display systems. However, existing optical waveguide lenses still face many challenges in terms of optical performance, manufacturing cost, and reliability. For example, users' performance requirements and application scenarios for products vary. The diffractive optical waveguide structure needs to be adjusted according to corresponding technical indicators. Therefore, diffractive optical waveguides have long faced the problem of customized development, resulting in a long iteration cycle and high cost for diffractive optical waveguides.

[0003] During the customized development process, existing diffractive optical waveguides must be configured in cooperation with an optical engine with a specific field of view (FOV). If the FOV of the optical engine is adjusted, the structure of the diffractive optical waveguide also needs to be redesigned and optimized. This leads to the update and iteration of diffractive optical waveguide products being extremely dependent on customized waveguide solutions to meet the one-to-one matching with the optical engine. However, due to the high processing cost and long production cycle of grating templates, this also brings a high economic cost to the development of waveguide products. Currently, most diffractive optical waveguides that can meet the transmission conditions of a large FOV can support smaller FOV transmission conditions, that is, the waveguide solution can be downward compatible but not upward compatible. However, diffractive optical waveguides with a large FOV usually have a very large turning area, which will cause a significant increase in the volume of the optical waveguide lens, affecting the user's wearing experience and aesthetics. Moreover, as the area of the diffraction grating structure increases, the processing cost and difficulty also increase.

[0004] Based on the above problems, the utility model proposes a diffractive optical waveguide that can be upward compatible with multiple FOV transmission conditions. Users only need to adjust the specifications of the projection optical engine to achieve different FOV visual experiences without changing the optical waveguide lens, which can reduce the manufacturing cost of the diffractive optical waveguide and achieve one structure with multiple uses. In addition, the upward compatibility mentioned in the utility model can ensure good imaging quality at different FOVs while ensuring beauty and low manufacturing cost. Summary of the Utility Model

[0005] The problem to be solved by the utility model is to provide a glass-plastic hybrid optical waveguide lens for the above-mentioned deficiencies in the prior art, which has the advantages of being thin and light, having good optical performance, and being able to be upward compatible with optical engines within the range of 20° to 50° FOV.

[0006] The above utility model object of the utility model is achieved through the following technical solutions:

[0007] A glass-plastic hybrid optical waveguide lens comprises a waveguide substrate with a diffraction grating structure, and plasticized film layers symmetrically arranged on both sides of the waveguide substrate, the refractive index of the waveguide substrate is 1.5-2.0, the grating period of the diffraction grating structure is 200-450nm, the refractive index of the plasticized film layer is 1.2-1.8, and the light transmission path of the optical waveguide lens passes through the waveguide substrate, the diffraction grating structure and at least one plasticized film layer to complete the coordination with an optical machine within a FOV range of 20-50°.

[0008] By adopting the above technical solution, the waveguide substrate is composed of an inorganic transparent material with a relatively high refractive index of 1.5~2.0, and a coupling-in area, a turning area and / or a coupling-out area are arranged on the surface of at least one side of the waveguide substrate, and a diffraction grating structure is manufactured by means of embossing, etching, etc., so that the light from the optical machine within the FOV range of 20~50° is imaged on the diffraction grating structure in the coupling-out area after two-dimensional pupil expansion; wherein the area of ​​the diffraction grating structure is designed according to the transmission requirements of the minimum FOV, and under a smaller FOV, the plasticized film layer on the side of the incident light plays a refracting role, and the plasticized film layers on both sides only play a protective role, and when the FOV increases, the plasticized film layer on the side away from the incident light also plays a refracting role, assisting in completing the complete total reflection, thereby regulating the light transmission path, so that The total reflection distance of light propagating in the waveguide is increased, which is conducive to adjusting the problem of large light efficiency loss caused by too short total reflection distance in some edge FOVs, thereby ensuring the uniformity of the overall transmission of the waveguide; in addition, for the plasticized film layer obtained by spin coating or coating, it is equivalent to filling the inside of the grating ridge of the diffraction grating structure, which is also conducive to improving the uniformity of the coupled light to a certain extent; by adopting the above structure, the optical waveguide lens itself has the characteristics of being extremely light and thin, and the total weight is approximately equal to the weight of the waveguide substrate. For a single-layer waveguide, the weight is usually not more than 0.5g, and because the refractive index of the waveguide substrate can be relatively large, it can simultaneously support the total reflection of RGB three colors in the waveguide, so that the lens can be extremely light and thin, with an overall thickness of no more than 1mm.

[0009] The utility model is further configured as follows: the waveguide substrate is a composite sheet of one or more of optical glass, silicon carbide wafer and lithium niobate wafer.

[0010] By adopting the above technical solutions, the material selection of the waveguide substrate has a crucial impact on the performance of the optical waveguide lens. Optical glass has good transparency and a relatively high refractive index, making it suitable for manufacturing high-quality waveguide substrates. Silicon carbide wafers have excellent thermal conductivity and mechanical strength, capable of withstanding high temperatures and mechanical stresses, and are suitable for use in harsh environments. Lithium niobate wafers, due to their excellent electro-optic effect and nonlinear optical properties, have broad application prospects in optical waveguide lenses. By using these materials selectively, their respective advantages can be fully utilized to improve the comprehensive performance of the waveguide substrate.

[0011] The present utility model is further configured as: the grating in the diffraction grating structure is a combined grating composed of one or several of an inclined grating, a trapezoidal grating, a blazed grating, a curved grating, and a rectangular grating.

[0012] By adopting the above technical solutions, the grating in the diffraction grating structure can be a one-dimensional grating or a two-dimensional grating. The specific shape of the diffraction grating structure is not restricted by any conditions. It is only necessary to control the grating period within the range of 200nm to 450nm according to the selection of the glass material.

[0013] The present utility model is further configured as: the diffraction grating structure includes a one-dimensional coupling grating, a one-dimensional turning grating, and a one-dimensional output grating arranged in sequence along the light transmission path. The grating period of the one-dimensional coupling grating is 200 - 450nm, the grating height is 30 - 500nm, and the duty cycle is 20 - 80%. The grating period of the one-dimensional turning grating is 200 - 450nm, the grating height is 10 - 300nm, and the duty cycle is 20 - 80%. The grating period of the one-dimensional output grating is 200 - 450nm, the grating height is 10 - 300nm, and the duty cycle is 20 - 80%.

[0014] By adopting the above technical solutions, upward compatibility with opto-mechanics within the range of 20 - 50° FOV can be achieved.

[0015] The present utility model is further configured as: the diffraction grating structure includes a one-dimensional coupling grating and a two-dimensional output grating arranged in sequence along the light transmission path. The grating period of the one-dimensional coupling grating is 200 - 450nm, the grating height is 30 - 500nm, and the duty cycle is 20 - 80%. The grating period of the two-dimensional output grating is 200 - 450nm, the grating height is 10 - 300nm, and the duty cycle is 20 - 80%.

[0016] By adopting the above technical solutions, upward compatibility with opto-mechanics within the range of 20 - 50° FOV can be achieved.

[0017] The present utility model is further configured such that: the plasticized film layer is a combined film layer of one or several of an optical resin coating, a PC hardening liquid coating, a polyethylene film layer, and a polypropylene film layer.

[0018] By adopting the above technical solution, the plasticized film layer is covered on the surface of the waveguide substrate by means of spin coating, film laminating, injection molding, coating, dipping, etc. The refractive index is usually between 1.2 and 1.8, which is lower than the refractive index of the waveguide substrate, and can assist in achieving upward compatibility of the FOV.

[0019] The present utility model is further configured such that: the thickness of the plasticized film layer is 3 to 500 μm.

[0020] By adopting the above technical solution, the waveguide lens can be protected from scratches, dirt, etc.

[0021] The present utility model is further configured such that: the thickness of the optical waveguide lens is within 1.0 mm.

[0022] By adopting the above technical solution, while being as thin and light as possible, the optical performance of the optical waveguide lens can be ensured.

[0023] The present utility model is further configured such that: the optical waveguide lens further includes an anti-reflection film disposed on the plasticized film layer.

[0024] By adopting the above technical solution, the film system design of the anti-reflection film is related to the substrate material selected for the optical waveguide, and can further improve the transmittance of external ambient light.

[0025] The present utility model is further configured such that: the anti-reflection film layer is a combined film layer of at least two of a silicon dioxide film layer, a titanium dioxide film layer, and a silicon nitride film layer.

[0026] By adopting the above technical solution, the anti-reflection film layer is stacked by the above materials with refractive index differences, and can further improve the transmittance of external ambient light.

[0027] In summary, the beneficial technical effects of the present utility model are as follows:

[0028] 1. By optimizing the waveguide substrate material and diffraction grating structure design, efficient coupling of the optical machine within a wide field of view (FOV) range is achieved, thereby improving the transmission efficiency and uniformity of the optical waveguide lens;

[0029] 2. By adopting a thin and light waveguide substrate material, the optical waveguide lens has an extremely low weight, is suitable for long-term wearing, especially for head-mounted display devices, and reduces the burden on users;

[0030] 3. By using a combination of materials with different refractive indices, total internal reflection of RGB three-color light is achieved, ensuring color accuracy and clarity, and providing users with a high-quality visual experience;

[0031] 4. Utilizing the protective effect of the plasticized film layer effectively prevents the waveguide lens from being scratched and contaminated during use, extending the service life of the product;

[0032] 5. The introduction of the anti-reflection film layer further improves the light transmittance of the optical waveguide lens, reduces the reflection and scattering of ambient light, makes the image clearer, and at the same time reduces the interference of glare and reflected light on the user's vision;

[0033] 6. By precisely controlling the period and angle of the diffraction grating structure, compatibility with different FOVs is achieved, enabling the optical waveguide lens to adapt to a variety of different application scenarios and improving the product's scope of application;

[0034] 7. The design of the optical waveguide lens of the present utility model not only meets the requirements of modern display technology for thinness, high definition, and high efficiency, but also has good environmental adaptability and durability, providing a solid technical foundation for the further development of head-mounted display devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of the plastic hybrid optical waveguide lens of Embodiment 1 of the present utility model.

[0036] Figure 2 is a k-space schematic diagram of the plastic hybrid optical waveguide lens of Embodiment 1 of the present utility model.

[0037] Figure 3 is a schematic diagram of the light transmission path of the plastic hybrid optical waveguide lens of Embodiment 1 of the present utility model at 30° FOV.

[0038] Figure 4 is a schematic diagram of the light transmission path of the plastic hybrid optical waveguide lens of Embodiment 1 of the present utility model at 50° FOV.

[0039] Figure 5 is a k-space schematic diagram of the plastic hybrid optical waveguide lens of Embodiment 2 of the present utility model.

[0040] Figure 6 is a schematic structural diagram of the diffraction grating structure of the existing optical waveguide lens of Embodiment 2 of the present utility model.

[0041] Figure 7 is a k-space schematic diagram of the plastic hybrid optical waveguide lens of Embodiment 3 of the present utility model.

[0042] Figure 8Schematic diagram of the imaging effect of the plastic hybrid optical waveguide lens in Embodiment 3 of the present utility model at 35° FOV.

[0043] Figure 9 Schematic diagram of the imaging effect of the plastic hybrid optical waveguide lens in Embodiment 3 of the present utility model at 50° FOV.

[0044] In the figure, 1 is the waveguide substrate; 2 is the diffraction grating structure; 21 is the one-dimensional coupling grating; 22 is the one-dimensional turning grating; 23 is the one-dimensional output grating; 24 is the two-dimensional output grating; 3 is the plasticized film layer; 4 is the antireflection film layer. Detailed implementation manners

[0045] 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 drawings and specific implementation manners.

[0046] Embodiment 1: Refer to Figure 1 , a glass-plastic hybrid optical waveguide lens disclosed by the present utility model, includes a waveguide substrate 1 with a diffraction grating structure 2, and a plasticized film layer 3 and an antireflection film layer 4 symmetrically arranged on both sides of the waveguide substrate 1 in sequence. Among them, the light transmission path of the optical waveguide lens passes through the waveguide substrate 1, the diffraction grating structure 2, at least one plasticized film layer 3, and the antireflection film layer 4. In order to complete the upward compatibility and cooperation with the optical engine within the range of 30° to 50° FOV, the technical parameters of the above are as follows.

[0047] First of all, the waveguide substrate 1 is an optical glass with a refractive index of 2.0.

[0048] Secondly, the grating in the diffraction grating structure 2 is a rectangular grating, and the diffraction grating structure 2 includes a one-dimensional coupling grating 21, a one-dimensional turning grating 22 and a one-dimensional output grating 23 arranged in sequence along the light transmission path. Among them, the coupling area of the waveguide substrate 1 is a circle with a radius R = 2 mm to facilitate the matching of the mouth of the optical engine; the grating period of the one-dimensional coupling grating 21 is 300 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 90°, the grating height is 272 nm, and the duty cycle is 38%; the grating period of the one-dimensional turning grating 22 is 212.2 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 45°, the grating height is 110 nm, and the duty cycle is 45%; the grating period of the one-dimensional output grating 23 is 300 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 0°, the grating height is 80 nm, and the duty cycle is 48%.

[0049] Thirdly, the plasticized film layer 3 is a PC hardening liquid coating with a refractive index of 1.4, and the thickness of the plasticized film layer 3 is 200 μm, and the thickness of the optical waveguide lens is within 0.7 mm.

[0050] Finally, the anti-reflection film layer 4 is a combined film layer obtained by sequentially coating a 76.86 nm titanium dioxide film layer, a 2210 nm silicon dioxide film layer, a 20.12 nm titanium dioxide film layer, a 105.88 nm silicon dioxide film layer, a 5.04 nm titanium dioxide film layer, and a 5.69 nm silicon dioxide film layer, and its transmittance in the visible light range is above 85%.

[0051] Referring to Figure 2 , under the condition of 30° FOV, the grating period of the one-dimensional coupling grating 21 in the coupling region is determined in advance. From the maximum and minimum values k1 and k2 of the k-vector distribution in the FOV of the coupling region, the boundaries AB and CD on the left and right sides of the one-dimensional turning grating 22 in the turning region can be obtained. Due to the coupling and decoupling relationships, the specific position of the one-dimensional decoupling grating 23 in the decoupling region can be determined. Referring to Figure 3 , according to the light transmission path of 30° FOV, total internal reflection of all the light rays of the optical machine only occurs on the waveguide substrate 1, and the plasticized film layer 3 only plays a role in protecting the grating here.

[0052] The above optical waveguide lens can also be applied to an optical machine with a 50° FOV. The left and right boundaries of the one-dimensional turning grating 22 in the theoretically obtained turning region are obtained by the same method as above, that is, the two lines EF and GH corresponding to the maximum and minimum values k3 and k4 of the k-vector distribution respectively. Since the coupling and decoupling relationships remain unchanged, the gratings in the coupling region and the decoupling region can remain unadjusted. That is, in principle, when the FOV of the optical machine increases from 30° to 50°, the size of the one-dimensional turning grating 22 in the turning region should be appropriately enlarged. However, the enlarged size of the turning region is significantly smaller than the size of the incident light spot, that is, if no enlargement is performed, the part larger than 30° FOV can still be diffracted by the one-dimensional turning grating 22 in the turning region. Referring to Figure 4 , from the perspective of k-space, after the FOV increases, total internal reflection of the light rays in some of the marginal FOVs will be completed through the plasticized film layer 3. The light rays complete a complete total internal reflection through the plasticized film layer 3, which increases the total internal reflection distance of the light rays propagating in the waveguide substrate 1. This is beneficial to adjusting the problem of large optical efficiency loss caused by too short total internal reflection distance in some of the marginal FOVs, thereby ensuring the uniformity of the overall waveguide transmission. In addition, for the plasticized film layer 3 obtained by spin coating or coating PC hardening liquid, it is equivalent to filling inside the grating ridges, which also helps to improve the uniformity of the decoupled light rays to a certain extent.

[0053] Example 2: Referring to Figure 5, a glass-plastic hybrid optical waveguide lens disclosed by the present utility model. The difference from Embodiment 1 is that to achieve upward compatibility with an optical engine within a 20-50° FOV, the grating period of the one-dimensional coupling grating 21 is 320 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is -72°, the grating height is 280 nm, and the duty cycle is 67%; the grating period of the one-dimensional turning grating 22 is 253 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 57°, the grating height is 50 nm, and the duty cycle is 37%; the grating period of the one-dimensional output grating 23 is 310 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 8°, the grating height is 40 nm, and the duty cycle is 60%.

[0054] It can be foreseen that if the optical waveguide lens structure proposed in this embodiment is not adopted, waveguides with a large FOV can be downward compatible with those with a small FOV. However, the problem brought about by this is that the area of the diffraction grating structure 2 will be very large. Refer to Figure 6 , for a 60° FOV, the area of the turning region will be very large, which has an adverse impact on the overall aesthetics and the total area of the lens. However, if the optical waveguide lens structure proposed in this embodiment is adopted, referring to the case mentioned above, the structural area of the turning region will be significantly reduced, which not only improves the aesthetics of the optical waveguide but also reduces the manufacturing cost and processing difficulty of the lens.

[0055] Embodiment 3: Refer to Figure 7 , a glass-plastic hybrid optical waveguide lens disclosed by the present utility model. The difference from Embodiment 1 is that to achieve upward compatibility with an optical engine within a 35-50° FOV, the waveguide substrate 1 is an optical glass with a refractive index of 1.9, and the plasticized film layer 3 is a polyethylene film layer with a refractive index of 1.4.

[0056] The grating in the diffraction grating structure 2 is a rectangular grating, and the diffraction grating structure 2 includes a one-dimensional coupling grating 21 and a two-dimensional output grating 24 arranged in sequence along the optical transmission path. Among them. The two-dimensional diffraction grating structure 2 adopted in the output region can simultaneously play the roles of turning and output. The grating period of the one-dimensional coupling grating 21 is 260 nm, the grating height is 150 nm, and the duty cycle is 68%. The gratings of the two-dimensional output grating 24 are arranged in a two-dimensional array along two mutually perpendicular directions, and the grating period of the two-dimensional output grating 24 is 260 nm, the grating height is 30 nm, and the duty cycle is 50%.

[0057] Refer to Figure 8 and Figure 9, the above optical waveguide lens structure can simultaneously support the requirements of 35° FOV and 50° FOV optical engines, obtaining imaging effect diagrams, so as to ensure that the light transmission requirements of different FOVs are met without changing the diffraction grating structure 2, and further proving the feasibility of the optical waveguide lens structure proposed by the present utility model in terms of compatible multi-FOV. In particular, by reasonably partitioning and designing the light extraction area, the light extraction efficiency and uniformity of the waveguide under different FOV conditions can be further improved.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and not to limit them. 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 purpose and scope of the technical solutions of the present utility model, and they should all be covered by the scope of the claims of the present utility model.

Claims

1. A glass-plastic hybrid optical waveguide lens, characterized in that: The invention comprises a waveguide substrate (1) with a diffraction grating structure (2), and plasticized film layers (3) symmetrically arranged on both sides of the waveguide substrate (1), wherein the refractive index of the waveguide substrate (1) is 1.5-2.0, the grating period of the diffraction grating structure (2) is 200-450 nm, and the refractive index of the plasticized film layer (3) is 1.2-1.

8. The light transmission path of the optical waveguide lens passes through the waveguide substrate (1), the diffraction grating structure (2) and at least one plasticized film layer (3), so as to complete the coordination with an optical machine within a FOV range of 20-50°.

2. The glass-plastic hybrid optical waveguide lens according to claim 1, characterized in that: The waveguide substrate (1) is a composite sheet of one or more of optical glass, silicon carbide wafer and lithium niobate wafer.

3. The glass-plastic hybrid optical waveguide lens according to claim 1, characterized in that: The grating in the diffraction grating structure (2) is 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.

4. The glass-plastic hybrid optical waveguide lens according to claim 3, characterized in that: The diffraction grating structure (2) comprises a one-dimensional coupling-in grating (21), a one-dimensional turning grating (22) and a one-dimensional coupling-out grating (23) which are sequentially arranged along a light transmission path; the one-dimensional coupling-in grating (21) has a grating period of 200-450 nm, a grating height of 30-500 nm and a duty cycle of 20-80%; the one-dimensional turning grating (22) has a grating period of 200-450 nm, a grating height of 10-300 nm and a duty cycle of 20-80%; and the one-dimensional coupling-out grating (23) has a grating period of 200-450 nm, a grating height of 10-300 nm and a duty cycle of 20-80%.

5. The glass-plastic hybrid optical waveguide lens according to claim 3, characterized in that: The diffraction grating structure (2) comprises a one-dimensional coupling-in grating (21) and a two-dimensional coupling-out grating (24) which are sequentially arranged along a light transmission path; the one-dimensional coupling-in grating (21) has a grating period of 200-450 nm, a grating height of 30-500 nm, and a duty cycle of 20-80%; and the two-dimensional coupling-out grating (24) has a grating period of 200-450 nm, a grating height of 10-300 nm, and a duty cycle of 20-80%.

6. The glass-plastic hybrid optical waveguide lens according to claim 1, characterized in that: The plasticized film layer (3) is a film layer composed of one or more of an optical resin coating, a PC hardening liquid coating, a polyethylene film layer and a polypropylene film layer.

7. The glass-plastic hybrid optical waveguide lens according to claim 6, characterized in that: The thickness of the plasticized film layer (3) is 3-500 μm.

8. The glass-plastic hybrid optical waveguide lens according to claim 7, characterized in that: The thickness of the optical waveguide lens is within 1.0 mm.

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