Diffractive optical waveguide and ar device
By placing a filler layer with a refractive index between the substrate and the protective layer, the refractive index ratio is adjusted, solving the problems of increased weight and reduced transmittance in the prior art. This results in higher light transmittance and lighter lenses, improving the user experience.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SEEV OPTOELECTRONICS TECHNOLOGY CO LTD
- Filing Date
- 2025-05-23
- Publication Date
- 2026-07-10
Smart Images
Figure CN224480588U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of diffractive waveguides, and more particularly to a diffractive waveguide and an AR device. Background Technology
[0002] With the development of AR technology, diffractive waveguide glasses, as one of the carriers of AR devices, have attracted much attention. A diffractive waveguide is a transparent display based on optical waveguide technology, which uses the principle of light diffraction to achieve image transmission and display.
[0003] Existing diffractive waveguide lenses frequently use high-refractive-index materials. However, the use of high-refractive-index materials leads to an increase in the overall weight of the lens and low transmittance, resulting in a poor user experience. Utility Model Content
[0004] This invention provides a diffractive waveguide and an AR device, which improves the transmittance of the diffractive waveguide, reduces the overall weight of the diffractive waveguide, and enhances the user experience by setting a filling layer with a refractive index between the substrate and the protective layer, and setting the refractive index ratio between the substrate and the filling layer and between the filling layer and the protective layer.
[0005] In a first aspect, the present invention provides a diffractive waveguide, comprising: a substrate, a grating structure located on one side surface of the substrate, a filling layer covering the grating structure, and a protective layer located on the side surface of the filling layer away from the substrate; the refractive index of the filling layer is between the refractive index of the substrate and the refractive index of the protective layer.
[0006] The refractive index ratio between the refractive index of the filling layer and the refractive index of the substrate is 0.3-0.95, and the refractive index ratio between the refractive index of the protective layer and the refractive index of the filling layer is 0.3-0.95.
[0007] Optionally, the refractive index difference between the substrate and the filling layer is 0.3-1.0, and the refractive index difference between the filling layer and the protective layer is 0.3-1.0.
[0008] Optionally, the refractive index of the filling layer is n1, the refractive index of the substrate is n2, and the refractive index of the protective layer is n3;
[0009] Among them, n1, n2 and n3 satisfy: n3<n1≤n2-0.3.
[0010] Optionally, the refractive index of the substrate is in the range of 1.5-3, and / or the thickness of the substrate is in the range of 0.1mm-1mm.
[0011] Optionally, the minimum thickness of the filler layer ranges from 200nm to 50um.
[0012] Optionally, the refractive index of the protective layer is in the range of 1.2-2.0, and / or the thickness of the protective layer is in the range of 25um-500um.
[0013] Optionally, the diffractive waveguide may also include a high-transmittance diffraction grating;
[0014] The high-transmittance diffraction grating is located on the surface of the protective layer away from the substrate.
[0015] Optionally, the period D of the high-transmission diffraction grating satisfies: D<λ / n2;
[0016] Where λ is the wavelength of the anti-transmission light from the high-transmission diffraction grating, and n2 is the refractive index of the substrate.
[0017] Optionally, the grating period of the high-transmission diffraction grating ranges from 25nm to 300nm, and / or the grating height of the high-transmission diffraction grating ranges from 20nm to 500nm.
[0018] Optionally, the morphology of the high-transmission diffraction grating includes at least straight gratings, blazed gratings, tilted gratings, polygonal gratings, quadratic curve gratings, or rotatable gratings.
[0019] Optionally, the diffractive waveguide may also include an antireflection coating;
[0020] The antireflective coating is located on the surface of the protective layer away from the substrate.
[0021] Optionally, the diffractive waveguide may further include a second filling layer, a third filling layer, and a fourth filling layer;
[0022] The second filler layer is located on the surface of the substrate facing away from the protective layer; the second filler layer is located on the side of the filler layer facing away from the substrate, and the second filler layer is framed and connected to the filler layer; the fourth filler layer is located on the surface of the protective layer facing away from the substrate.
[0023] Optionally, the refractive index of the substrate is greater than that of the filling layer and the second filling layer, and the refractive index of the protective layer is greater than that of the third filling layer and the fourth filling layer.
[0024] Secondly, this utility model provides an AR device, which is made using the aforementioned diffractive waveguide.
[0025] The technical solution of this utility model involves setting a filling layer between a substrate and a protective layer. This filling layer covers the grating structure, and the refractive index of the filling layer is between that of the substrate and the protective layer. The refractive index ratio between the filling layer and the substrate is set to 0.3-0.95, and the refractive index ratio between the protective layer and the filling layer is also set to 0.3-0.95. By utilizing this structure and setting the filling layer and the specific refractive index ratio ranges between the filling layer and the substrate and protective layer, the refractive index ratio between adjacent layers is increased, thereby improving the transmittance of light in the diffractive waveguide. Simultaneously, the weight of the diffractive waveguide is reduced, improving the user experience.
[0026] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 A schematic diagram of a diffractive optical waveguide provided for existing technology;
[0029] Figure 2 A schematic diagram of the deformation of a diffractive optical waveguide under stress, provided for the present technology;
[0030] Figure 3 A schematic diagram of a diffractive waveguide provided in an embodiment of this utility model;
[0031] Figure 4 A graph showing the relationship between the ratio of light transmittance to refractive index provided for an embodiment of this utility model;
[0032] Figure 5 A graph showing the relationship between the incident angle of light and different refractive index ratios, provided for an embodiment of this utility model;
[0033] Figure 6 A schematic diagram of the deformation of a diffractive waveguide under stress, provided for an embodiment of this utility model;
[0034] Figure 7 This is a schematic diagram of the structure of the second diffractive waveguide provided in an embodiment of the present invention;
[0035] Figure 8 A schematic diagram of a polygonal grating provided for an embodiment of this utility model;
[0036] Figure 9 A schematic diagram of a quadratic curve stereo grating provided for an embodiment of this utility model;
[0037] Figure 10 A schematic diagram of the structure of a rotating grating provided in an embodiment of this utility model;
[0038] Figure 11 A schematic diagram showing the relationship between the ratio of light transmittance to refractive index with and without a high-transmittance diffraction grating, provided for an embodiment of this utility model;
[0039] Figure 12 A schematic diagram of the relationship between incident angle and light transmittance under different refractive index ratios when using a high-transmittance diffraction grating, provided for an embodiment of this utility model;
[0040] Figure 13 This is a schematic diagram of the structure of the third type of diffractive waveguide provided in this embodiment of the present invention;
[0041] Figure 14 This is a schematic diagram of the structure of the fourth diffractive waveguide provided in this embodiment of the present invention;
[0042] Figure 15 A schematic diagram of a diffractive waveguide including a substrate is provided for an embodiment of this utility model;
[0043] Figure 16 A schematic diagram of a diffractive waveguide including a substrate and a high-transmittance diffraction grating, provided for an embodiment of this utility model;
[0044] Figure 17 This is a schematic diagram of a diffractive waveguide comprising a substrate, a filling layer, and a high-transmittance diffraction grating, provided for an embodiment of the present invention. Detailed Implementation
[0045] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.
[0046] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0047] Before introducing the technical solution of the present utility model embodiment, a brief description of the diffractive waveguide set in the prior art will be given first. Figure 1 A schematic diagram of a diffractive optical waveguide structure provided for the present technology. Figure 2 A schematic diagram of the deformation of a diffractive optical waveguide under stress, provided for reference in the prior art. Figure 1 and Figure 2 As shown, a diffractive waveguide includes a substrate, a grating structure (not shown) disposed on the substrate, and a protective layer. The protective layer is framed to the substrate. When subjected to stress, only the structures on both sides of the frame can offset the stress, while the middle portion lacks such stress-offsetting structures. This can lead to deformation and breakage of the diffractive waveguide. Therefore, to ensure that the diffractive waveguide does not break due to deformation, the thickness of the protective layer needs to be increased, which increases the weight of the final diffractive waveguide. Furthermore, in the fabrication of diffractive waveguides, the refractive index of the substrate is increasingly higher, while the refractive index of the protective layer remains relatively constant. This reduces the refractive index ratio of the air between the protective layer and the substrate to that of the substrate, resulting in a decrease in the transmittance of the diffractive waveguide.
[0048] To prevent deformation and breakage of the diffractive waveguide, and to reduce its overall weight and improve its light transmittance, this embodiment provides a diffractive waveguide structure. Figure 3 This is a schematic diagram of a diffractive waveguide provided in an embodiment of the present invention. Figure 4 A graph showing the relationship between the ratio of light transmittance to refractive index is provided for an embodiment of this utility model. Figure 5 This invention provides a graph showing the relationship between the incident angle of light and different refractive index ratios. Figure 6 This is a schematic diagram illustrating the deformation of a diffractive waveguide under stress, provided as an embodiment of the present invention. This embodiment is applicable to situations where the transmittance of a diffractive waveguide is improved and the overall weight of the diffractive waveguide is reduced, such as... Figures 3 to 6As shown, the diffractive waveguide includes: a substrate 1, a grating structure 11 located on one side surface of the substrate 1, a filling layer 2 covering the grating structure 11, and a protective layer 3 located on the side surface of the filling layer 2 away from the substrate 1; the refractive index of the filling layer 2 is between the refractive index of the substrate 1 and the refractive index of the protective layer 3; the refractive index ratio between the refractive index of the filling layer 2 and the refractive index of the substrate 1 is 0.3-0.95, and the refractive index ratio between the refractive index of the protective layer 3 and the refractive index of the filling layer 2 is 0.3-0.95.
[0049] The substrate 1 is the core supporting structure of the diffractive waveguide, typically made of a transparent material with a high refractive index, such as glass, resin, oxide wafers, SiC wafers, or glass-ceramics. The substrate 1 provides a medium environment for light transmission, allowing light to propagate through total internal reflection. The grating structure 11 is a crucial part of the diffractive waveguide used to control light propagation. It typically includes micro- and nano-scale periodic structures, and its main functions are to couple light into the substrate 1, allow total internal reflection within the substrate 1, and couple light out of the substrate 1 to enter the human eye. In this embodiment, the grating structure 11 may include an insertion grating, a transition grating, and an exit grating. The filling layer 2 is an optical medium layer, typically comprising a material with a specific refractive index between that of the substrate 1 and the protective layer 3, allowing the filling layer 2 to act as a transition and control layer in the optical system of the diffractive waveguide. The protective layer 3 is a material layer covering the surface of the filling layer 2, used to prevent the grating structure 11 from being affected by the external environment. The refractive index ratio is the ratio between the refractive index of the material with the smaller refractive index and the refractive index of the material with the larger refractive index.
[0050] Specifically, in diffractive waveguides, a protective layer 3 is typically disposed on the surface of the grating structure 11 of the substrate 1, with air between the substrate 1 and the protective layer 3. Due to the small refractive index ratios between air and substrate 1, and between air and protective layer 3, the transmittance of existing diffractive waveguides is low. (Reference) Figure 4 It can be seen that there is a positive correlation between the light transmittance and the refractive index ratio η of the adjacent two structures. That is, the higher the refractive index ratio η, the higher the light transmittance, and the lower the refractive index ratio η, the lower the light transmittance. Based on the above principle, in order to improve the transmittance of the diffractive waveguide, this embodiment sets a filling layer 2 between the substrate 1 and the protective layer 3, so that the refractive index of the filling layer 2 is between the refractive index of the substrate 1 and the refractive index of the protective layer 3, and the refractive index ratio between the refractive index of the filling layer 2 and the refractive index of the substrate 1 is set to be 0.3-0.95, and the refractive index ratio between the refractive index of the protective layer 3 and the refractive index of the filling layer 2 is also set to be 0.3-0.95. In this way, by increasing the refractive index ratio of the adjacent two structures, the light transmittance in the diffractive waveguide is increased.
[0051] Furthermore, the refractive index ratio between the filling layer 2 and the substrate 1, and the refractive index ratio between the protective layer 3 and the filling layer 2, can preferably be set to 0.5-0.95 as needed. Figure 5 , Figure 5 The example illustrates the relationship between the angle of incidence and light transmittance when the refractive index ratio η is 0.5, 0.7, and 0.9. The horizontal axis represents the angle of incidence, and the vertical axis represents the light transmittance. It can be seen that, for a constant angle of incidence, the light transmittance is lowest when the refractive index ratio η is 0.5, highest when η is 0.9, and falls between the two when η is 0.7. This further verifies that the larger the refractive index ratio η, the higher the transmittance. Furthermore, for the same refractive index ratio η, the relationship between the angle of incidence and light transmittance initially remains constant and then decreases. During the decreasing phase, the larger the angle of incidence, the lower the light transmittance. This is because the light deviates too much from the interface normal, and since light is a transverse wave, it is more difficult for it to pass through. Furthermore, the larger the refractive index ratio η, the more the descending part of the curve is to the right. This means that under the same light transmittance, a diffractive waveguide with a larger refractive index ratio allows for a larger incident angle. In other words, a higher refractive index ratio can still maintain a higher light transmittance at a larger incident angle, showing better optical performance. That is to say, good optical display can also be obtained at a large field of view.
[0052] Additionally, refer to Figure 6 In this embodiment, by inserting a filler layer 2 with a refractive index between the substrate 1 and the protective layer 3 and having adhesive properties, the refractive index ratio of the two adjacent layers is increased. At the same time, the bonding method is changed from frame bonding to full bonding, which increases the toughness of the diffractive waveguide lens under stress and reduces the possibility of deformation and breakage. Therefore, in the case of full bonding, the thickness of the protective layer 3 can be reduced, making the protective layer 3 thinner, thereby reducing the overall weight of the diffractive waveguide.
[0053] It should be noted that the refractive index ratio between the substrate 1 and the filling layer 2 is 0.3-0.95. For example, the refractive index ratio between the substrate 1 and the filling layer 2 can be 0.3, 0.5, 0.7, 0.8, or 0.95, etc., and can be determined according to the actual situation; no limitation is imposed here. Similarly, the refractive index ratio between the filling layer 2 and the protective layer 3 is 0.3-0.95. For example, the refractive index ratio between the filling layer 2 and the protective layer 3 can be 0.3, 0.5, 0.7, 0.8, or 0.95, etc., and can be determined according to the actual situation; no limitation is imposed here.
[0054] The technical solution of this utility model embodiment involves setting a filling layer between the substrate and the protective layer. The filling layer covers the grating structure, and the refractive index of the filling layer is between that of the substrate and the protective layer. The refractive index ratio between the filling layer and the substrate is set to 0.3-0.95, and the refractive index ratio between the protective layer and the filling layer is also set to 0.3-0.95. Using this structure, by setting the filling layer and the specific refractive index ratio ranges between the filling layer and the substrate and protective layer, the refractive index ratio between adjacent layers is increased, thereby improving the transmittance of light in the diffractive waveguide. Simultaneously, the weight of the diffractive waveguide is reduced, improving the user experience.
[0055] In another specific embodiment, optionally, reference continues. Figure 3 The refractive index difference between the refractive index of the filling layer 2 and the refractive index of the substrate 1 is 0.3-1.0, and the refractive index difference between the refractive index of the protective layer 3 and the refractive index of the filling layer 2 is 0.3-1.0.
[0056] Specifically, the refractive index difference can be expressed as the difference between the refractive index of the material with a higher refractive index and the refractive index of the material with a lower refractive index. It can be understood that a larger refractive index difference indicates a greater difference in refractive indices between adjacent layers, resulting in a smaller calculated refractive index ratio; conversely, a smaller refractive index difference indicates a smaller difference in refractive indices between adjacent layers, resulting in a larger calculated refractive index ratio. In other words, the refractive index difference and the refractive index ratio are inversely proportional. That is, to improve the transmittance of the diffracted waveguide, it is necessary to reduce the refractive index difference between adjacent layers. In this embodiment, the refractive index difference between the filling layer 2 and the substrate 1 is set to 0.3-1.0. For example, the refractive index difference between the filling layer 2 and the substrate 1 can be 0.3, 0.5, 0.7, 0.9, or 1.0, etc., and can be determined according to the actual situation, without limitation here. The refractive index difference between the protective layer 3 and the filling layer 2 is 0.3-1.0. For example, the refractive index difference between the protective layer 3 and the filling layer 2 can be 0.3, 0.5, 0.7, 0.9, or 1.0, etc., which can be determined according to the actual situation and are not limited here. Preferably, the refractive index difference between the filling layer 2 and the substrate 1, and the refractive index difference between the protective layer 3 and the filling layer 2 are preferably in the range of 0.3-0.5.
[0057] Optional, continue to refer to Figure 3 The refractive index of the filling layer 2 is n1, the refractive index of the substrate 1 is n2, and the refractive index of the protective layer 3 is n3; wherein, n1, n2, and n3 satisfy: n3 < n1 ≤ n2 - 0.3.
[0058] Specifically, the refractive index of the filling layer 2 is set to be less than or equal to the difference between the refractive index of the substrate 1 and 0.3. This is to ensure that the light transmitted in the substrate 1 can maintain total internal reflection and ultimately exit from the coupling grating of the grating structure 11 to the human eye, while also ensuring light uniformity. Furthermore, the refractive index of the protective layer 3 is set to be less than that of the filling layer 2. This is to ensure that the refractive index of the filling layer 2 is between the refractive index of the substrate 1 and the refractive index of the protective layer 3, thereby improving light transmittance.
[0059] Optional, continue to refer to Figure 3 The refractive index of substrate 1 is in the range of 1.5-3, and / or the thickness of substrate 1 is in the range of 0.1mm-1mm.
[0060] Specifically, the refractive index of substrate 1 ranges from 1.5 to 3. For example, the refractive index of substrate 1 can be 1.5, 2, 2.5, or 3, and can be determined according to the actual situation, without limitation. In addition, in this embodiment, the thickness of substrate 1 is set to range from 0.1mm to 1mm. For example, the thickness of substrate 1 can be 0.1mm, 0.3mm, 0.5mm, 0.8mm, or 1mm, and can be determined according to the actual situation, without limitation.
[0061] Optional, continue to refer to Figure 3 The refractive index of the protective layer 3 is in the range of 1.2-2.0, and / or the thickness of the protective layer 3 is in the range of 25um-500um.
[0062] Specifically, the refractive index of the protective layer 3 ranges from 1.2 to 2.0. For example, the refractive index of the protective layer 3 can be 1.2, 1.5, 1.8, or 2.0, and can be determined according to the actual situation; no limitation is imposed here. Furthermore, in this embodiment, the thickness of the protective layer 3 is set to range from 25µm to 500µm. For example, the thickness of the protective layer 3 can be 25µm, 100µm, 200µm, 300µm, 400µm, or 500µm, and can be determined according to the actual situation; no limitation is imposed here.
[0063] Optional, continue to refer to Figure 3 As shown, the minimum thickness of the filling layer 2 ranges from 200nm to 50um.
[0064] The minimum thickness range of the filling layer 2 represents the distance between the side of the filling layer 2 away from the substrate 1 and the highest point of the grating structure 11. In this embodiment, the minimum thickness range H of the filling layer 2 is 200nm-50um. For example, the minimum thickness of the filling layer 2 can be 200nm, 500nm, 1um, 10um, 30um, or 50um, which can be determined according to the actual situation and is not limited here. It should be noted that if the minimum thickness of the filling layer 2 is set to less than 200nm, the filling layer 2 will affect the diffraction modulation of the light effect, resulting in poor diffraction modulation effect; it may also make it easier for photons to tunnel through the waveguide interface due to insufficient barrier height for tunneling, resulting in non-total internal reflection and affecting the optical performance of the diffractive waveguide.
[0065] In another specific embodiment, optionally, Figure 7 This is a schematic diagram of the structure of the second diffractive waveguide provided in this embodiment of the present invention. Figure 8 This is a schematic diagram of the structure of a polygonal grating provided in an embodiment of the present invention. Figure 9 This is a schematic diagram of the structure of a quadratic curve stereo grating provided in an embodiment of the present invention. Figure 10 This is a schematic diagram of the structure of a rotating grating provided in an embodiment of the present invention. Figure 11 This is a schematic diagram illustrating the relationship between the ratio of light transmittance to refractive index with and without a high-transmittance diffraction grating, provided as an embodiment of this utility model. Figure 12 A schematic diagram illustrating the relationship between incident angle and light transmittance at different refractive index ratios for a high-transmittance diffraction grating, provided as an embodiment of this utility model, is shown below. Figures 7 to 12 As shown, the diffraction waveguide also includes a high-transmittance diffraction grating 4; the high-transmittance diffraction grating 4 is located on the surface of the protective layer 3 away from the substrate 1.
[0066] Optionally, the period D of the high-transmission diffraction grating satisfies: D < λ / n2; where λ is the wavelength of the anti-transmission ray of the high-transmission diffraction grating 4, and n2 is the refractive index of the substrate 1.
[0067] Optionally, the morphology of the high-transmission diffraction grating 4 includes at least a straight grating, a blazed grating, a tilted grating, a polygonal grating, a quadratic curve grating, or a gyratory grating.
[0068] The high-transmittance diffraction grating 4 is an optical element that modulates light using the principle of light diffraction. The high-transmittance diffraction grating 4 typically includes a series of equally spaced scribes or grooves. These scribes or grooves can cause light of a specific wavelength to diffract, thereby achieving beam splitting, redirection, and energy modulation of the light. In this embodiment, the high-transmittance diffraction grating 4 may include one-dimensional and two-dimensional gratings, with arbitrary grating shapes, including but not limited to straight gratings, blazed gratings, tilted gratings, polygonal gratings, quadratic curve gratings, or solid-of-rotation gratings. (Reference) Figure 8 As shown, a polygonal grating is a grating whose horizontal cross-section can be decomposed into a closed shape consisting of three or more straight lines connected end to end. (Reference) Figure 9 As shown, a quadratic curve grating is a cylindrical, frustum, or conical grating whose horizontal cross-section is a quadratic curve such as a circle or ellipse. (Reference) Figure 10 As shown, the rotary grating is a three-dimensional grating formed by a closed two-dimensional image around an axis.
[0069] Specifically, the period D of the high-transmittance diffraction grating 4 satisfies: D < λ / n², where λ is the wavelength of the light transmitted through the high-transmittance diffraction grating 4, and n² is the refractive index of the substrate 1. When the period of the high-transmittance diffraction grating 4 satisfies the above condition, and the refractive index ratio between the refractive index of the protective layer 3 and the refractive index of the filling layer 2 is within the range of 0.3-0.95, the light transmittance can be further improved by utilizing the modulation effect of the high-transmittance diffraction grating 4. (Reference) Figure 10 Let η be the refractive index ratio and the incident angle be 0°. It can be seen that when the high-transmittance diffraction grating 4 is not set on the surface of the protective layer 3 away from the substrate 1, the light transmittance gradually increases for different refractive index ratios; that is, the larger the refractive index ratio, the higher the light transmittance. After the refractive index ratio reaches a certain value, the light transmittance remains constant. When the high-transmittance diffraction grating 4 is set on the surface of the protective layer 3 away from the substrate 1, the light transmittance for different refractive index ratios remains basically unchanged and is higher than the light transmittance without the high-transmittance diffraction grating 4. In other words, setting the high-transmittance diffraction grating 4 can further improve the light transmittance, thereby improving the optical performance of the diffraction waveguide.
[0070] Additionally, refer to Figure 12 , Figure 12The example demonstrates the relationship between the incident angle and light transmittance when the high-transmittance diffraction grating 4 is set, with refractive index ratios η being 0.5, 0.7, and 0.9. The horizontal axis represents the incident angle, and the vertical axis represents the light transmittance. It can be seen that when the incident angle is between 0° and 56°, the light transmittance corresponding to different refractive index ratios η is approximately equal, and the light transmittance is approximately 100%. In the latter half of the incident angle range, i.e., between 56° and 88°, the light transmittance corresponding to different refractive index ratios η gradually decreases with increasing incident angle. Specifically, the light transmittance is highest when the refractive index ratio η is 0.9, lowest when the refractive index ratio η is 0.5, and intermediate when η is 0.7. This further verifies that the larger the refractive index ratio η, the higher the transmittance. In other words, for the same refractive index ratio η, the relationship between the incident angle and light transmittance initially remains constant and then decreases. For the latter half of the decreasing curve, the larger the incident angle, the smaller the light transmittance. This is because the light deviates too much from the interface normal, and since light is a transverse wave, it is more difficult to pass through. Furthermore, the larger the refractive index ratio η, the further to the right the decreasing portion of the curve, meaning that for the same light transmittance, a diffractive waveguide with a larger refractive index ratio allows for a larger incident angle. In other words, a higher refractive index ratio maintains higher light transmittance even at larger incident angles, exhibiting better optical performance.
[0071] Optional, continue to refer to Figure 7 As shown, the grating period of the high-transmittance diffraction grating 4 ranges from 25nm to 300nm, and / or the grating height of the high-transmittance diffraction grating 4 ranges from 20nm to 500nm.
[0072] Specifically, the grating period of the high-transmittance diffraction grating 4 ranges from 25nm to 300nm. For example, the grating period range of the high-transmittance diffraction grating 4 can be 25nm, 100nm, 200nm, 250nm, or 300nm, and can be determined according to actual conditions; no limitation is imposed here. Furthermore, in this embodiment, the grating height of the high-transmittance diffraction grating 4 is set to a range of 20nm to 500nm. For example, the grating height range of the high-transmittance diffraction grating 4 can be 20nm, 100nm, 200nm, 300nm, 400nm, or 500nm, and can be determined according to actual conditions; no limitation is imposed here.
[0073] In another specific embodiment, optionally, Figure 13 This is a schematic diagram of the third type of diffractive waveguide provided in this embodiment of the present invention, with reference to... Figure 13 As shown, the diffractive waveguide also includes an antireflection film 5; the antireflection film 5 is located on the surface of the protective layer 3 away from the substrate 1.
[0074] The anti-reflective coating (AR) 5 is a thin film coated on the surface of an optical element. Its main function is to reduce light reflection loss when passing through the medium and improve light transmittance. In this embodiment, when the refractive index ratio between the refractive index of the protective layer 3 and the refractive index of the filling layer 2 is in the range of 0.3-0.95, the anti-reflective coating is easier to design. At this time, by increasing the refractive index ratio, setting the anti-reflective coating 5 will further improve the light transmittance effect, achieving high transmittance. That is to say, a thinner anti-reflective coating 5 with fewer layers can achieve the same or better transmittance effect.
[0075] In another specific embodiment, optionally, Figure 14 This is a schematic diagram of the fourth type of diffractive waveguide provided in this embodiment of the present invention, with reference to... Figure 14 As shown, the diffractive waveguide also includes a second filling layer 6, a third filling layer 7, and a fourth filling layer 8; the second filling layer 6 is located on the surface of the substrate 1 away from the protective layer 3; the third filling layer 7 is located on the filling layer 2 away from the substrate 1, and the third filling layer 7 is frame-connected to the filling layer 2; the fourth filling layer 8 is located on the surface of the protective layer 3 away from the substrate 1.
[0076] In this structure, the side of the substrate 1 away from the protective layer 3 is filled with air, the space between the filling layer 2 and the protective layer 3 is filled with air, the side of the protective layer 3 away from the substrate is filled with air, the second filling layer 6 is used to modulate the refractive index between the substrate 1 and the air, the third filling layer 7 is used to modulate the refractive index between the air and the protective layer 3, and the fourth filling layer 8 is used to modulate the refractive index between the air and the protective layer 3 to improve the refractive index ratio.
[0077] Optional, continue to refer to Figure 14 The refractive index of substrate 1 is greater than that of filling layer 2 and the second filling layer 6, and the refractive index of protective layer 3 is greater than that of the third filling layer 7 and the fourth filling layer 8. The refractive indices of the second filling layer 6 and the filling layer 2 may be equal or unequal, and this is not a restriction. Similarly, the refractive indices of the third filling layer 7 and the fourth filling layer 8 may be equal or unequal, and this is not a restriction.
[0078] In one specific embodiment, reference is made to Figure 14The refractive index of substrate 1 is n2 = 2.0, and the refractive index of protective layer 3 is n3 = 1.5. A third filling layer 7 and a fourth filling layer 8 are inserted at the air interface on both sides of protective layer 3. The refractive indices of the third filling layer 7 and the fourth filling layer 8 are equal, both n4 = 1.3. A filling layer 2 and a second filling layer 6 are inserted at the air interface on both sides of substrate 1. The refractive indices of filling layer 2 and the second filling layer 6 are equal, both n1 = 1.7. The third filling layer 7 is attached using a frame-mount method, and its light transmittance is determined by the interface... The transmittance calculations for the surfaces yielded the following results: the air refractive index n5 = 1, the refractive index ratio between air and the fourth filling layer 8 η1 = 1 / 1.3 = 0.77, and the interfacial transmittance T1 between air and the fourth filling layer 8 = 98.30%; the refractive index ratio between the fourth filling layer 8 and the protective layer 3 η2 = 1.3 / 1.5 = 0.87, and the interfacial transmittance T2 between the fourth filling layer 8 and the protective layer 3 = 99.50%; the refractive index ratio between the protective layer 3 and the third filling layer 7 η3 = ... 1.3 / 1.5 = 0.87, the interfacial transmittance T3 between protective layer 3 and third filler layer 7 is 99.50%; the refractive index ratio η4 between third filler layer 7 and air is 1 / 1.3 = 0.77, the interfacial transmittance T4 between third filler layer 7 and air is 98.30%; the refractive index ratio η5 between air and filler layer 2 is 1 / 1.7 = 0.59, the interfacial transmittance T5 between air and filler layer 2 is 93.28%; the refractive index ratio between filler layer 2 and substrate 1 is... The refractive index ratio η6 = 1.7 / 2 = 0.85, and the interfacial transmittance between the filling layer 2 and the substrate 1 is T6 = 99.34%; the refractive index ratio between the substrate 1 and the second filling layer 6 is η7 = 1.7 / 2 = 0.85, and the interfacial transmittance between the substrate 1 and the second filling layer 6 is T7 = 99.34%; the refractive index ratio between the second filling layer 6 and air is η8 = 1 / 1.7 = 0.59, and the interfacial transmittance between the second filling layer 6 and air is T8 = 93.28%. Therefore, the total transmittance T of this diffractive waveguide can be expressed as T = T1*T2*T3*T4*T5*T6*T7*T8 = 98.30%*99.50%*99.50%*98.30%*93.28%*99.34%*99.34%*93.28% = 82.14%, which greatly improves the light transmittance of the diffractive waveguide.
[0079] In one specific embodiment, in the prior art, reference is made to... Figure 1The substrate has a refractive index of 2.0, and the protective layer has a refractive index of 1.5. The bonding method is frame bonding. The transmittance is calculated by multiplying the transmittance of each interface: the refractive index ratio between air n1.0 and the protective layer n1.5 is 0.67, and the transmittance of the interface between air n1.0 and the protective layer n1.5 is 96.00%; the refractive index ratio between air n1.0 and the substrate n2.0 is 0.5, and the transmittance of the interface between air n1.0 and the substrate n2.0 is 88.89%. At this time, the overall transmittance of the diffractive waveguide is T = 96.00% * 96.00% * 88.89% * 88.89% = 72.82%.
[0080] To improve the transmittance of the diffractive waveguide, refer to Figure 3 In this embodiment, a filler layer 2 with a refractive index between the substrate 1 and the protective layer 3 is provided. The refractive index of the substrate 1 is 2.0, the refractive index of the protective layer 3 is 1.5, and the refractive index of the filler layer 2 is 1.7. The bonding method is full bonding. The transmittance is calculated from the transmittance of each interface: the refractive index of air is 1.0, the refractive index ratio between air and the protective layer 3 is 0.67, and the transmittance of the interface between air and the protective layer 3 is 96.00%; the refractive index ratio between the protective layer 3 and the filler layer 2 is 0.88, and the transmittance of the interface between the protective layer 3 and the filler layer 2 is 99.60%; the refractive index ratio between the filler layer 2 and the substrate 1 is 0.85, and the transmittance of the interface between the filler layer 2 and the substrate 1 is 99.34%; the refractive index ratio between air and the substrate 1 is 0.5, and the transmittance of the interface between air and the substrate 1 is 88.89%. At this point, the overall transmittance of the diffractive waveguide is T = 96.00% * 99.60% * 99.34% * 88.89% = 84.43%. It can be seen that the transmittance of the diffractive waveguide is greatly improved compared with the existing technology.
[0081] In another embodiment, reference Figure 14By setting filling layers on both sides of the substrate 1 and the protective layer 3, the refractive index of the substrate 1 is n2 = 2.0 and the refractive index of the protective layer 3 is n3 = 1.5. A third filling layer 7 and a fourth filling layer 8 are inserted at the air interface on both sides of the protective layer 3. The refractive indices of the third filling layer 7 and the fourth filling layer 8 are equal, both n4 = 1.3. A filling layer 2 and a second filling layer 6 are inserted at the air interface on both sides of the substrate 1. The refractive indices of the filling layer 2 and the second filling layer 6 are equal, both n1 = 1.7. The third filling layer 7 is attached... The bonding method is frame bonding, and its light transmittance is calculated from the transmittance of each interface: the refractive index of air is n5 = 1, the refractive index ratio between air and the fourth filling layer 8 is η1 = 1 / 1.3 = 0.77, and the transmittance of the interface between air and the fourth filling layer 8 is T1 = 98.30%; the refractive index ratio between the fourth filling layer 8 and the protective layer 3 is η2 = 1.3 / 1.5 = 0.87, and the transmittance of the interface between the fourth filling layer 8 and the protective layer 3 is T2 = 99.50%; the transmittance of the interface between the third filling layer 7 and the protective layer 3 is... The refractive index ratio between the protective layer 3 and the third filling layer 7 is η3 = 1.3 / 1.5 = 0.87, and the interfacial transmittance T3 between the protective layer 3 and the third filling layer 7 is 99.50%; the refractive index ratio between air and the third filling layer 7 is η4 = 1 / 1.3 = 0.77, and the interfacial transmittance T4 between the third filling layer 7 and air is 98.30%; the refractive index ratio between air and filling layer 2 is η5 = 1 / 1.7 = 0.59, and the interfacial transmittance T5 between air and filling layer 2 is 93.28%; the refractive index ratio between filling layer 2 and the base layer 7 ...3 = 1.3 / 1.5 = 0.87, and the interfacial transmittance T3 between the protective layer 3 and the third filling layer 7 is 99.50%; the refractive index ratio between air and filling layer 2 is η5 = 1 / 1.7 = 0.59, and the interfacial transmittance T5 between air and filling layer 2 is 93.28%; the refractive index ratio between filling layer 2 and the base layer 7 is η4 = 1 / 1.3 = 0.77, and the interfacial transmittance T4 between the third filling layer 7 and air is 98.30%; the refractive index ratio between air and filling layer 2 is η5 = 1 / 1.7 = 0.59, and the interfacial transmittance T5 between air and filling layer 2 is 93.28%; the refractive index ratio between filling layer 2 and the base layer The refractive index ratio between the two layers is η6 = 1.7 / 2 = 0.85, and the interfacial transmittance between the filling layer 2 and the substrate 1 is T6 = 99.34%; the refractive index ratio between the second filling layer 6 and the substrate 1 is η7 = 1.7 / 2 = 0.85, and the interfacial transmittance between the substrate 1 and the second filling layer 6 is T7 = 99.34%; the refractive index ratio between air and the second filling layer 6 is η8 = 1 / 1.7 = 0.59, and the interfacial transmittance between the second filling layer 6 and air is T8 = 93.28%. Therefore, the total transmittance T of the diffractive waveguide can be expressed as T = T1*T2*T3*T4*T5*T6*T7*T8 = 98.30%*99.50%*99.50%*98.30%*93.28%*99.34%*99.34%*93.28% = 82.14%, which greatly improves the light transmittance of the diffractive waveguide compared with the existing technology.
[0082] In another embodiment, Figure 15 A schematic diagram of a diffractive waveguide including a substrate is provided for an embodiment of this utility model. (Refer to...) Figure 15As shown, the substrate is surrounded by air on both sides. The refractive index of the substrate is 2, and the refractive index of the air is 1. The refractive index ratio between air n1.0 and substrate n2.0 is 0.5. When light rays at a large angle of 80° are incident on the diffractive waveguide, the transmittance at the interface between air n1.0 and substrate n2.0 is 57.27%. Therefore, the total transmittance T of the diffractive waveguide can be expressed as T = 57.27% * 57.27% = 32.8%.
[0083] When a high-transmission diffraction grating is set on one side of the substrate, Figure 16 A schematic diagram of a diffraction waveguide including a substrate and a high-transmittance diffraction grating is provided for an embodiment of this utility model. (Refer to...) Figure 16 As shown, the refractive index of the substrate is 2, the refractive index of air is 1, and the refractive index ratio between air n1.0 and substrate n2.0 is 0.5. When light rays at a large angle of 80° are incident on the diffractive waveguide, the transmittance at the interface between air n1.0 and substrate n2.0 is 57.27%. Because a high-transmittance diffraction grating is provided on one side of the substrate, the transmittance at the interface between substrate n2.0 and air n1.0 is 74.15%. Therefore, the total transmittance T of the diffractive waveguide can be expressed as T = 57.27% * 74.15% = 42.47%. It can be seen that compared with the diffractive waveguide without a high-transmittance diffraction grating, its light transmittance is increased by 9.67%.
[0084] Figure 17 A schematic diagram of a diffractive waveguide comprising a substrate, a filling layer, and a high-transmittance diffraction grating, provided for an embodiment of this utility model, is shown below. Figure 17 As shown, the refractive index of the substrate is 2, the refractive index of air is 1, and the refractive index of the filling layer is 1.5. The refractive index ratio between air n1.0 and substrate n2.0 is 0.5. When light rays at a large angle of 80° are incident on the diffractive waveguide, the transmittance at the interface between air n1.0 and substrate n2.0 is 57.27%, the refractive index ratio between filling layer n1.5 and substrate n2.0 is 0.75, and the transmittance at the interface between filling layer n1.5 and substrate n2.0 is 97.49%. Because a high-transmittance diffraction grating is provided on the side of the substrate facing the filling layer, the transmittance between air n1.0 and the filling layer... The refractive index ratio between n1.5 is 0.67, and the interfacial transmittance between air n1.0 and the filling layer n1.5 is 81.18%. Therefore, the total transmittance T of the diffractive waveguide can be expressed as T = 57.27% * 97.49% * 81.18% = 45.32%. It can be seen that compared with the diffractive waveguide without a high-transmittance diffraction grating, its light transmittance is increased by 12.52%, and compared with the diffractive waveguide with a high-transmittance diffraction grating only on one side of the substrate, its light transmittance is increased by 2.85%, which greatly improves the transmittance of the diffractive waveguide.
[0085] Based on the same inventive concept, this utility model provides an AR device, which is made using the above-mentioned diffractive waveguide and has the corresponding functional modules and beneficial effects of the diffractive waveguide.
[0086] It should be understood that the various forms of the process shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this utility model can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this utility model can be achieved, and this is not limited herein.
[0087] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.
Claims
1. A diffractive optical waveguide, characterized in that, include: A substrate, a grating structure located on one side surface of the substrate, a filling layer covering the grating structure, and a protective layer located on the side surface of the filling layer away from the substrate; The refractive index of the filling layer is between that of the substrate and the refractive index of the protective layer; The refractive index ratio between the refractive index of the filling layer and the refractive index of the substrate is 0.3-0.95, and the refractive index ratio between the refractive index of the protective layer and the refractive index of the filling layer is 0.3-0.
95.
2. The diffractive waveguide according to claim 1, characterized in that, The refractive index difference between the substrate and the filling layer is 0.3-1.0, and the refractive index difference between the filling layer and the protective layer is 0.3-1.
0.
3. The diffractive waveguide according to claim 1, characterized in that, The refractive index of the filling layer is n1, the refractive index of the substrate is n2, and the refractive index of the protective layer is n3. Among them, n1, n2 and n3 satisfy: n3<n1≤n2-0.
3.
4. The diffractive waveguide according to claim 1, characterized in that, The refractive index of the substrate is in the range of 1.5-3, and / or the thickness of the substrate is in the range of 0.1mm-1mm.
5. The diffractive waveguide according to claim 1, characterized in that, The minimum thickness of the filling layer ranges from 200 nm to 50 μm.
6. The diffractive waveguide according to claim 1, characterized in that, The refractive index of the protective layer is in the range of 1.2-2.0, and / or the thickness of the protective layer is in the range of 25um-500um.
7. The diffractive waveguide according to claim 1, characterized in that, It also includes high-transmission diffraction gratings; The high-transmittance diffraction grating is located on the surface of the protective layer away from the substrate.
8. The diffractive waveguide according to claim 7, characterized in that, The period D of the high-transmittance diffraction grating satisfies: D<λ / n2; Wherein, λ is the wavelength of the anti-transmission light of the high-transmission diffraction grating, and n2 is the refractive index of the substrate.
9. The diffractive waveguide according to claim 8, characterized in that, The grating period of the high-transmittance diffraction grating is in the range of 25nm-300nm, and / or the grating height of the high-transmittance diffraction grating is in the range of 20nm-500nm.
10. The diffractive waveguide according to claim 7, characterized in that, The morphology of the high-transmittance diffraction grating includes at least a straight grating, a blazed grating, a tilted grating, a polygonal grating, a quadratic curve grating, or a rotatable grating.
11. The diffractive waveguide according to claim 1, characterized in that, It also includes antireflective coatings; The antireflective film is located on the surface of the protective layer away from the substrate.
12. The diffractive waveguide according to claim 1, characterized in that, It also includes a second filler layer, a third filler layer, and a fourth filler layer; The second filling layer is located on the surface of the substrate facing away from the protective layer; the second filling layer is located on the side of the filling layer facing away from the substrate, and the second filling layer is framedly connected to the filling layer; the fourth filling layer is located on the surface of the protective layer facing away from the substrate.
13. The diffractive waveguide according to claim 12, characterized in that, The refractive index of the substrate is greater than that of the filling layer and the second filling layer, and the refractive index of the protective layer is greater than that of the third filling layer and the fourth filling layer.
14. An AR device, characterized in that, It is prepared using the diffractive waveguide described in any one of claims 1-13.