Anti-glare diffraction optical waveguide

Abstract

The utility model relates to an anti-dazzle diffraction optical waveguide, which comprises a waveguide substrate with at least two diffraction grating structures, the refractive index of the waveguide substrate is more than 1.8, and the at least two diffraction grating structures are respectively and independently arranged to be a one-dimensional grating structure or a two-dimensional grating structure. Gratings of the two-dimensional grating structure are arranged in a two-dimensional array along two mutually perpendicular directions, and the grating period of the diffraction grating structure is 230-320 nm, so that the diffraction optical waveguide is approximately free of ambient light coupling out within a predetermined FOV range. The grating parameters and the structure of the diffraction optical waveguide are optimized, after ambient light is modulated by the diffraction grating structure, the diffracted light is totally reflected in the waveguide substrate and is coupled out along the direction forming an included angle with the surface of the waveguide substrate, and the coupled-out ambient light does not enter a visual range (namely a preset FOV range) of human eyes. Therefore, the purpose of eliminating glare is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of diffractive optical waveguides, and in particular to an anti-glare diffractive optical waveguide. Background Art

[0002] Diffractive optical waveguide technology can image a virtual picture in front of the user's eyes through the turning of the optical path by setting periodic grating structures in different position regions, realizing seamless integration of virtual and reality. AR glasses adopting diffractive optical waveguide technology have become one of the most promising solutions in the AR field due to their thin and light design and mass production advantages. However, while the periodic grating array helps to achieve imaging, it also causes glare. Ambient light diffracts after passing through the periodic grating structure on the lens surface, resulting in colored bright areas in front of the user's eyes, which significantly reduces the user experience of AR glasses.

[0003] To address the glare challenge in AR diffractive optical waveguides, a number of patented technologies such as CN111886447A and CN214097983U have respectively proposed innovative solutions. These technologies start from multiple aspects to reduce the glare problem by adjusting the direction of the grating vector, optimizing the grating structure parameters, introducing suppression zones in specific grating regions, etc. However, adjusting the grating structure parameters must be carried out without compromising the good imaging effect of the waveguide and also meet other design requirements of the product, which limits the flexibility of the adjustment. In addition, although adding suppression zones in specific regions can alleviate the glare problem to a certain extent, this will increase the complexity of the manufacturing process, raise the production cost, and may affect the aesthetic appearance of the lens. Summary of the Utility Model

[0004] The problem to be solved by the utility model is to provide an anti-glare diffractive optical waveguide aiming at the above-mentioned deficiencies in the prior art. Through optimizing the grating parameters and structure of the diffractive optical waveguide, after the ambient light is modulated by the diffractive grating structure, the diffracted light 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, and the coupled-out ambient light does not enter the visible range of the human eye (i.e., the predetermined FOV range), thereby achieving the purpose of eliminating glare.

[0005] The above-mentioned utility model purpose of the utility model is achieved through the following technical solutions:

[0006] An anti-glare diffractive optical waveguide includes a waveguide substrate with a diffractive grating structure. The refractive index of the waveguide substrate is above 1.8. The diffractive grating structure is provided with at least two, and each is independently set as a one-dimensional grating structure or a two-dimensional grating structure. The gratings of the two-dimensional grating structure are arranged in a two-dimensional array along two mutually perpendicular directions. The grating period of the diffractive grating structure is 230-320 nm, so that the diffractive optical waveguide is approximately free of ambient light extraction within a predetermined FOV range.

[0007] By adopting the above technical solution, ambient light After passing through the diffractive grating structure Due to the existence of the periodic structure, it may cause the diffraction behavior of light, and the extracted light Satisfy ; For the human eye, there is a visible FOV angle range, that is, the light within a certain angle range can be observed, and the part beyond it actually cannot enter the human eye and be seen; as Figure 1 As shown in (a), assuming that the absolute value of k0 is 1, the maximum angle range θ that the human eye can observe is represented by the dotted circle in the figure, and the radius of the dotted circle represents the maximum field of view angle , if it is desired that the ambient light decays in the form of an evanescent wave after being modulated by the diffractive grating structure, then it should satisfy 1, as shown in the figure And Shown; actually, if the ambient light is diffracted and does not enter the human eye range, it can be not observed by the human eye, and the effect of completely suppressing the glare phenomenon can also be achieved, that is ; Due to , it can be seen from this that , λ min Is the minimum wavelength in the visible light range;

[0008] However, at the same time, the grating vector of the diffractive grating structure also needs to ensure that the conventional light satisfies the total reflection condition during transmission in the diffractive optical waveguide. As Figure 1 As shown in (b), the gray circle represents the FOV of the virtual image. Let the maximum field of view angle (i.e., the diagonal field of view angle) be α, then the radius of the gray circle , to satisfy the total reflection condition, it is necessary to ensure , n represents the refractive index of the waveguide substrate, then there is , λ is the wavelength of the virtual image; thus, the value range of the grating vector of the diffractive grating structure is determined. It can be seen that for a specific waveguide substrate (with a refractive index above 1.8), there is a theoretical minimum value (≥230 nm) for the grating period to meet the total reflection requirement, and at the same time, there is a maximum value (≤320 nm) to ensure that the human eye cannot observe the glare phenomenon; in actual selection, these two conditions should be matched, that is ; If there is a contradiction between the two, that is When it comes to this, first ensure that the diffraction grating structure can meet the total reflection condition;

[0009] In the waveguide substrate, except for the decoupling region, there is also a periodic diffraction grating structure in the turning region, which can theoretically diffract ambient light as well. Therefore, during the design process, it is also necessary to suppress the diffraction phenomenon of some structures at the same time; as Figure 1 As shown in the k diagram of the diffraction optical waveguide in (c), assuming that the grating vector G3 in the decoupling region has been set according to the above-mentioned period requirements, which not only meets the total reflection condition but also has no glare phenomenon at all; then, the grating vector G2 in the turning region can also be modulated accordingly to ensure ; As can be seen from the figure, by jointly controlling the directions of G1 and G2, this condition can be easily achieved, and at the same time, the grating vectors satisfy the closed relationship, and the diffraction optical waveguide can normally couple out the light in the virtual image; as Figure 1 Shown in (d), it represents that according to Figure 1 the grating vector direction set in (c), the direction of the wave vector of the ambient light after being modulated by G2 and G3 can be obtained. It can be seen that the ambient light modulated by the grating does not enter the visible range of the human eye, that is, the glare phenomenon is completely eliminated.

[0010] The present utility model is further configured such that: the refractive index of the waveguide substrate is 1.9 to 2.7.

[0011] By adopting the above technical solution, it is ensured that while eliminating glare, good imaging effects and low production costs are maintained. Specifically, by precisely controlling the refractive index of the waveguide substrate within the range of 1.9 to 2.7, the diffraction efficiency can be further improved while reducing unnecessary light loss.

[0012] The present utility model is further configured such that: the grating period of the diffraction grating structure is 237 to 310 nm.

[0013] By adopting the above technical solution, the grating period of the diffraction grating structure is further optimized, which can effectively suppress the glare phenomenon while meeting the total reflection condition; specifically, by setting the grating period within the range of 237 to 310 nanometers (237~310nm), it can be ensured that the diffraction optical waveguide has almost no ambient light coupled out within the predetermined field of view (FOV), so as to achieve the purpose of eliminating glare.

[0014] The present utility model is further configured such that: there are three diffraction grating structures, and the three diffraction grating structures are sequentially arranged as a one-dimensional coupling grating, a one-dimensional turning grating, and a one-dimensional decoupling grating along the light transmission path.

[0015] By adopting the above technical solutions, the performance and efficiency of the optical waveguide are further improved; specifically, by sequentially arranging three diffraction grating structures on the optical transmission path, namely, a one-dimensional coupling grating, a one-dimensional turning grating, and a one-dimensional output grating, the propagation path and diffraction behavior of light can be more precisely controlled; the one-dimensional coupling grating is responsible for effectively coupling external light into the waveguide substrate, while the one-dimensional turning grating is responsible for changing the propagation direction of light inside the waveguide. Finally, the one-dimensional output grating guides the light out of the waveguide substrate and projects it into the user's eyes; this phased grating structure design not only improves the utilization rate of light but also reduces unnecessary scattering and loss caused by the grating structure, thus ensuring a high-quality image display effect.

[0016] The present utility model is further configured such that: the grating period of the one-dimensional coupling grating (21) is 200 - 350 nm, the grating height is 30 - 500 nm, and the duty cycle is 20 - 80%.

[0017] By adopting the above technical solutions, by optimizing the direction and structural parameters of the grating vector, the present utility model realizes effective suppression of the glare phenomenon without adding an additional suppression area.

[0018] The present utility model is further configured such that: the grating period of the one-dimensional turning grating is 200 - 350 nm, the grating height is 10 - 300 nm, and the duty cycle is 20 - 80%.

[0019] By adopting the above technical solutions, by optimizing the direction and structural parameters of the grating vector, the present utility model realizes effective suppression of the glare phenomenon without adding an additional suppression area.

[0020] The present utility model is further configured such that: the grating period of the one-dimensional coupling grating is 200 - 350 nm, the grating height is 10 - 300 nm, and the duty cycle is 20 - 80%.

[0021] By adopting the above technical solutions, by optimizing the direction and structural parameters of the grating vector, the present utility model realizes effective suppression of the glare phenomenon without adding an additional suppression area.

[0022] The present utility model is further configured such that: there are two diffraction grating structures, and the two diffraction grating structures are sequentially arranged as a one-dimensional coupling grating and a two-dimensional output grating along the optical transmission path.

[0023] By adopting the above technical solutions, the performance and efficiency of the optical waveguide are further improved. Specifically, by sequentially arranging three diffraction grating structures, namely a one-dimensional coupling grating and a two-dimensional coupling-out grating, on the optical transmission path, the propagation path and diffraction behavior of light can be controlled more precisely. The one-dimensional coupling grating is responsible for effectively coupling external light into the waveguide substrate, while the two-dimensional coupling-out grating is responsible for guiding the light out of the waveguide substrate and projecting it into the user's eyes, and at the same time realizing more complex light regulation to meet different display requirements. This phased grating structure design not only improves the utilization rate of light, but also reduces unnecessary scattering and loss caused by the grating structure, thus ensuring a high-quality image display effect.

[0024] The present utility model is further configured such that: the grating period of the one-dimensional coupling grating is 200 - 350 nm, the grating height is 30 - 300 nm, and the duty cycle is 20 - 80%.

[0025] By adopting the above technical solutions, by optimizing the direction and structural parameters of the grating vector, the present utility model realizes effective suppression of the glare phenomenon without adding an additional suppression area.

[0026] The present utility model is further configured such that: the grating period of the two-dimensional coupling-out grating is 200 - 350 nm, the grating height is 10 - 300 nm, and the duty cycle is 20 - 80%.

[0027] By adopting the above technical solutions, by optimizing the direction and structural parameters of the grating vector, the present utility model realizes effective suppression of the glare phenomenon without adding an additional suppression area.

[0028] In summary, the beneficial technical effects of the present utility model are as follows: by optimizing the grating parameters and structure of the diffractive optical waveguide, after the ambient light is modulated by the diffraction grating structure, the diffracted light 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, and the coupled-out ambient light does not enter the visible range of the human eye (i.e., the predetermined FOV range), thereby achieving the purpose of eliminating glare. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the grating vector of the diffractive optical waveguide of the present utility model.

[0030] Figure 2 is a schematic structural diagram of the diffractive optical waveguide according to Embodiment 1 of the present utility model.

[0031] Figure 3 is a schematic structural diagram of the diffractive optical waveguide according to Embodiment 2 of the present utility model.

[0032] Figure 4 is a schematic structural diagram of the diffractive optical waveguide according to Embodiment 3 of the present utility model.

[0033] Figure 5 It is a schematic structural diagram of the diffractive optical waveguide of Comparative Example 1 of the present utility model.

[0034] Figure 6 It is the ambient light distribution diagram coupled out by the diffractive optical waveguides of Examples 1 to 3 and Comparative Example 1 of the present utility model.

[0035] 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. Detailed implementation manners

[0036] 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 with reference to the accompanying drawings and specific implementation manners.

[0037] Example 1: Refer to Figure 2 , a glare-proof diffractive optical waveguide disclosed by the present utility model, includes a waveguide substrate 1 with a diffraction grating structure 2. Among them, for the waveguide substrate 1 with a specific refractive index, by optimizing the direction and structural parameters of the grating vector, the diffractive optical waveguide is approximately free of ambient light coupling output within a predetermined FOV range.

[0038] First, the refractive index of the waveguide substrate 1 is 1.9.

[0039] Secondly, three diffraction grating structures 2 are provided, and the three diffraction grating structures 2 are sequentially arranged as a one-dimensional coupling grating 21, a one-dimensional turning grating 22, and a one-dimensional output grating 23 along the light transmission path.

[0040] The one-dimensional coupling grating 21 is set as a one-dimensional rectangular grating. The grating period of the one-dimensional coupling grating 21 is 310 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is ~70°, the grating height is 320 nm, and the duty ratio is 65%.

[0041] The one-dimensional turning grating 22 is set as a one-dimensional rectangular grating. The grating period of the one-dimensional turning grating 22 is 237 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 59°, the grating height is 100 nm, and the duty ratio is 50%.

[0042] The one-dimensional output grating 23 is set as a one-dimensional rectangular grating. 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 10°, the grating height is 80 nm, and the duty ratio is 52%.

[0043] Example 2: Refer to Figure 3, an anti-glare diffractive optical waveguide disclosed by the present utility model, includes a waveguide substrate 1 with a diffraction grating structure 2. Among them, for the waveguide substrate 1 with a specific refractive index, by optimizing the direction and structural parameters of the grating vector, the diffractive optical waveguide approximately has no ambient light coupled out within a predetermined FOV range.

[0044] First, the refractive index of the waveguide substrate 1 is 2.7.

[0045] Secondly, three diffraction grating structures 2 are provided, and the three diffraction grating structures 2 are sequentially arranged as a one-dimensional coupling grating 21, a one-dimensional turning grating 22, and a one-dimensional coupling-out grating 23 along the light transmission path.

[0046] The one-dimensional coupling grating 21 is arranged as a one-dimensional rectangular grating. The grating period of the one-dimensional coupling grating 21 is 260 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is ~60°, the grating height is 220 nm, and the duty cycle is 55%.

[0047] The one-dimensional turning grating 22 is arranged as a one-dimensional rectangular grating. The grating period of the one-dimensional turning grating 22 is 260 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 60°, the grating height is 120 nm, and the duty cycle is 47%.

[0048] The one-dimensional coupling-out grating 23 is arranged as a one-dimensional rectangular grating. The grating period of the one-dimensional coupling grating 21 is 260 nm, the included angle between the grating vector and the length direction of the waveguide substrate 1 is 0°, the grating height is 53 nm, and the duty cycle is 60%.

[0049] Example 3: Refer to Figure 4 , an anti-glare diffractive optical waveguide disclosed by the present utility model, includes a waveguide substrate 1 with a diffraction grating structure 2. Among them, for the waveguide substrate 1 with a specific refractive index, by optimizing the direction and structural parameters of the grating vector, the diffractive optical waveguide approximately has no ambient light coupled out within a predetermined FOV range.

[0050] First, the refractive index of the waveguide substrate 1 is 2.3.

[0051] Secondly, two diffraction grating structures 2 are provided, and the two diffraction grating structures 2 are sequentially arranged as a one-dimensional coupling grating 21 and a two-dimensional coupling-out grating 24 along the light transmission path. The gratings of the two-dimensional coupling-out grating 24 are arranged in a two-dimensional array along two mutually perpendicular directions.

[0052] The one-dimensional coupling grating 21 is arranged as a one-dimensional rectangular grating. The grating period of the one-dimensional coupling grating 21 is 302 nm, the grating height is 180 nm, and the duty cycle is 56%.

[0053] The two-dimensional output grating 24 is set as a two-dimensional rectangular grating. The grating period of the two-dimensional output grating 24 is 302 nm, the grating height is 32 nm, and the duty cycle is 50%.

[0054] Comparative Example 1: Refer to Figure 5 , which is an anti-glare diffractive optical waveguide disclosed by the present utility model. The difference from Example 3 is that the gratings of the two-dimensional output grating 24 are arranged in a two-dimensional array along two directions with an included angle of 120°.

[0055] Test Example 1: The diffractive optical waveguides of Examples 1 to 3 and Comparative Example 1 were tested for diffraction conditions to determine the distribution of light rays diffracted by the environmental light by the diffraction grating structure 2. The results are as Figure 6 shown.

[0056] From Figure 6 Figures (a) to (b), it can be seen that in Example 1, after the environmental light is modulated by the gratings in the turning area and the output area, very few light rays that can meet the diffraction conditions will exist, and no diffraction pattern generated by the environmental light can be observed within the Eye-box range;

[0057] From Figure 6 Figures (c) to (d), it can be seen that in Example 2, only a small part of the blue light with a shorter wavelength can be output through the grating area. These light rays have a large diffraction angle and cannot enter the Eye-box range;

[0058] From Figure 6 Figures (e) to (f), it can be seen that in Figure 6 Figure (f), for Comparative Example 1, the gratings in the output area are arranged in a common diamond-shaped period. Under this condition, some light rays in the peripheral field of view will be received by the human eye. The period arrangement of the two-dimensional grating will also affect the diffraction of the environmental light to a certain extent. Under the condition that the period values are equal, while in Figure 6 Figure (e), the glare phenomenon caused by the rectangular period distribution in Example 3 will be weakened, and some diffraction of the environmental light will be eliminated due to the period arrangement of the grating (the diffracted light at the top corner position of the rectangle in the figure disappears); therefore, under the same period calculation method, for the two-dimensional grating structure, choosing the rectangular period arrangement is more beneficial for preventing glare.

[0059] 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 purpose 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. An anti-glare diffraction optical waveguide, characterized in that: The invention comprises a waveguide substrate (1) with a diffraction grating structure (2), wherein the refractive index of the waveguide substrate (1) is above 1.8, the diffraction grating structure (2) is provided with at least two, and each is independently provided as a one-dimensional grating structure or a two-dimensional grating structure, the gratings of the two-dimensional grating structure are arranged in a two-dimensional array along two directions perpendicular to each other, and the grating period of the diffraction grating structure (2) is 230-320nm, so that the diffraction light waveguide has approximately no ambient light outcoupling within a predetermined FOV range.

2. The anti-glare diffraction optical waveguide according to claim 1, characterized in that: The refractive index of the waveguide substrate (1) is 1.9-2.

7.

3. The anti-glare diffraction optical waveguide according to claim 2, characterized in that: The grating period of the diffraction grating structure (2) is 237-310 nm.

4. The anti-glare diffraction optical waveguide according to claim 3, characterized in that: The diffraction grating structures (2) are provided in three numbers, and the three diffraction grating structures (2) are sequentially arranged along the light transmission path as a one-dimensional coupling-in grating (21), a one-dimensional turning grating (22), and a one-dimensional coupling-out grating (23).

5. The anti-glare diffraction optical waveguide according to claim 4, characterized in that: The one-dimensional coupling grating (21) has a grating period of 200-350 nm, a grating height of 30-500 nm, and a duty cycle of 20-80%.

6. The anti-glare diffraction optical waveguide according to claim 4, characterized in that: The one-dimensional turning grating (22) has a grating period of 200-350 nm, a grating height of 10-300 nm, and a duty cycle of 20-80%.

7. The anti-glare diffraction optical waveguide according to claim 4, characterized in that: The one-dimensional coupling grating (21) has a grating period of 200-350 nm, a grating height of 10-300 nm, and a duty cycle of 20-80%.

8. The anti-glare diffraction optical waveguide according to claim 3, characterized in that: Two diffraction grating structures (2) are provided, and the two diffraction grating structures (2) are sequentially arranged as a one-dimensional coupling-in grating (21) and a two-dimensional coupling-out grating (24) along a light transmission path.

9. The anti-glare diffraction optical waveguide according to claim 8, characterized in that: The one-dimensional coupling grating (21) has a grating period of 200-350 nm, a grating height of 30-300 nm, and a duty cycle of 20-80%.

10. The anti-glare diffraction optical waveguide according to claim 8, characterized in that: The grating period of the two-dimensional outcoupling grating (24) is 200-350nm, the grating height is 10-300nm, and the duty cycle is 20-80%.

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