Diffractive optical waveguide

Abstract

The utility model provides a kind of diffractive optical waveguide, including at least one waveguide substrate sheet and at least one protective sheet;Waveguide substrate sheet at least contains one grating area;Protective sheet is located the side of waveguide substrate sheet and is provided with grating area;Diffractive optical waveguide further includes light regulation layer;Light regulation layer is used to realize the regulation of visible light transmittance, and realize anti ultraviolet ray.The diffractive optical waveguide provided by the utility model can effectively shield the irradiation of outdoor strong light, avoid the damage caused by ultraviolet rays to human eyes and equipment, and improve the environmental adaptation ability and service life of diffractive optical waveguide.

Description

Technical Field

[0001] This utility model relates to the field of display technology, and in particular to a diffractive optical waveguide. Background Technology

[0002] Diffractive waveguides are widely used in augmented reality (AR) and head-up display (HUD) technologies. AR glasses and HUDs, as core terminal devices, are rapidly gaining popularity in the consumer market, with their application scenarios expanding from professional fields to everyday life. In this process, users' performance requirements for AR glasses and HUDs are no longer limited to clear display of virtual images; they also place higher demands on the environmental adaptability and user experience of AR glasses and HUDs.

[0003] In the existing technology, the protection design of diffractive waveguides for the ultraviolet band has obvious defects: on the one hand, the excessively high ultraviolet transmittance cannot provide effective ultraviolet protection for the user's eyes, and long-term use can easily pose a risk to the user's eye health; on the other hand, the glass substrate and adhesive materials used in the core optical structure of the diffractive waveguide are easily degraded when exposed to ultraviolet radiation for a long time, which affects the stability of the optical performance of the diffractive waveguide and also shortens the service life of the product. Utility Model Content

[0004] This invention provides a diffractive waveguide that can effectively shield against strong outdoor light, prevent ultraviolet rays from damaging human eyes and equipment, and improve the environmental adaptability and service life of the diffractive waveguide.

[0005] This invention provides a diffractive waveguide, comprising at least one waveguide substrate and at least one protective sheet; the waveguide substrate contains at least one grating region; the protective sheet is located on the side of the waveguide substrate where the grating region is located.

[0006] The diffractive waveguide also includes a light modulation layer; the light modulation layer is used to adjust the transmittance of visible light and to achieve UV resistance.

[0007] Optionally, the light-regulating layer includes a color-changing layer and / or an anti-ultraviolet layer.

[0008] Optionally, the color-changing layer includes a photochromic layer and / or an electrochromic layer;

[0009] The color-changing layer is located on the side of the protective sheet away from the waveguide substrate; or, the color-changing layer is located on the side of the waveguide substrate away from the protective sheet.

[0010] Optionally, the color-changing layer includes a photochromic layer;

[0011] The photochromic layer and the protective sheet form an integrated composite structure. The composite structure is used to achieve a visible light transmittance range of 20% to 100% and an absorption rate of 80% to 99% in the long ultraviolet band.

[0012] Alternatively, the photochromic layer and the waveguide substrate form an integrated composite structure, which is used to achieve visible light transmittance ranging from 20% to 100% and absorption rate of 80% to 99% in the long ultraviolet band.

[0013] Optionally, the color-changing layer is embedded inside the protective sheet; the thickness of the color-changing layer is less than the thickness of the protective sheet, and the color-changing layer is used to achieve a visible light transmittance range of 20% to 100% and an absorption rate of 80% to 99% in the long ultraviolet band.

[0014] Alternatively, the color-changing layer is embedded inside the waveguide substrate, and the thickness of the color-changing layer is less than the thickness of the waveguide substrate. The color-changing layer is used to achieve visible light transmittance ranging from 20% to 100% and absorption rate of 80% to 99% in the long ultraviolet band.

[0015] Optionally, the light modulation layer may further include an anti-ultraviolet layer;

[0016] When the color-changing layer is located on the side of the protective sheet away from the waveguide substrate, the UV-resistant layer is located on the surface of the protective sheet facing the waveguide substrate; or, the UV-resistant layer is located on the surface of the waveguide substrate.

[0017] When the color-changing layer is located on the side of the waveguide substrate away from the protective sheet, the UV-resistant layer is located on the surface of the waveguide substrate facing the protective sheet; or, the UV-resistant layer is located on the surface of the protective sheet.

[0018] Optionally, the light modulation layer includes the UV-resistant layer;

[0019] The UV-resistant layer is located on the surface of the protective sheet on the side away from the waveguide substrate;

[0020] Alternatively, the UV-resistant layer is located on the surface of the protective sheet on the side facing the waveguide substrate;

[0021] Alternatively, the UV-resistant layer is located on the surface of the waveguide substrate facing the protective sheet;

[0022] Alternatively, the UV-resistant layer may be located on the surface of the waveguide substrate on the side away from the protective sheet.

[0023] Optionally, the UV-resistant layer includes a UV-resistant grating structure, satisfying:

[0024]

[0025] Wherein, D is the period of the UV-resistant grating structure. The refractive index of air, The refractive index of the waveguide substrate or the protective sheet. For light wavelengths in the long ultraviolet band, The wavelength of light is defined as the visible light band. In one embodiment, the long ultraviolet band is the UV-A band, and the wavelength of the long ultraviolet band is 315 nm to 380 nm.

[0026] Optionally, the color-changing layer includes a photochromic layer;

[0027] The photochromic layer includes multiple partitions distributed sequentially from the center outwards. Each partition includes a first partition and a second partition. The second partition at least partially surrounds the first partition. The content of photochromic material in the second partition is greater than the content of photochromic material in the first partition.

[0028] Optionally, the color-changing layer includes a photochromic layer;

[0029] From the center of the photochromic layer outwards, the content of the photochromic material in the photochromic layer gradually increases.

[0030] The diffractive waveguide proposed in this invention uses at least one waveguide substrate and at least one protective sheet to couple virtual image light into the waveguide. The light is then guided by a grating to propagate within the waveguide and ultimately transmitted to the user's eye. Combined with a light control layer, it achieves adjustment of outdoor visible light transmittance and UV protection, effectively shielding against strong outdoor light and preventing UV damage to the eyes and equipment. This enhances the environmental adaptability and lifespan of the diffractive waveguide. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a diffractive optical waveguide proposed in an embodiment of this utility model;

[0032] Figure 2 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the utility model;

[0034] Figure 4 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0039] Figure 9 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0040] Figure 10 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0041] Figure 11 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0042] Figure 12 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention;

[0043] Figure 13 This is a schematic diagram of a photochromic layer partitioning structure proposed in an embodiment of this utility model. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0045] Figure 1 This is a schematic diagram of a diffractive optical waveguide according to an embodiment of the present invention. (Refer to...) Figure 1This invention provides a diffractive waveguide, comprising at least one waveguide substrate 10 and at least one protective sheet 20; the waveguide substrate 10 contains at least one grating region; the protective sheet 20 is located on the side of the waveguide substrate 10 where the grating region is located. The diffractive waveguide also includes a light modulation layer 30; the light modulation layer 30 is used to adjust the transmittance of outdoor visible light and to achieve ultraviolet (UV) protection. In one embodiment, the light modulation layer 30 is used to change the transmittance of visible light and the absorption rate of UV rays. In another embodiment, the light modulation layer 30 is used to change the transmittance of visible light and the reflectance of UV rays.

[0046] For example, the waveguide substrate 10 and the protective sheet 20 are assembled in a frame-mount or fully laminated manner, and the grating region includes at least one of a one-dimensional grating, a two-dimensional grating, and a metasurface structure. In other embodiments, there may be other assembly methods for the waveguide substrate 10 and the protective sheet 20, as well as other types of grating regions.

[0047] Among them, such as Figure 1 In the example shown, the diffractive waveguide includes a waveguide substrate 10 and a protective sheet 20. For AR devices with different optical requirements, the diffractive waveguide may also include multiple waveguide substrates 10 and multiple protective sheets 20. This embodiment of the present invention does not limit this. This embodiment of the present invention takes each diffractive waveguide as an example, which includes a waveguide substrate 10 and a protective sheet 20, for exemplary description.

[0048] The material of the protective sheet 20 can be glass, resin, polycarbonate, nylon, etc., and this embodiment of the present invention does not limit this. The waveguide substrate 10 and the protective sheet 20 are assembled by frame bonding or full bonding. Frame bonding means that only the edge frame of the waveguide substrate 10 and the protective sheet 20 is glued and fixed, leaving an air layer in the middle. Frame bonding is simple, but air and dust can easily enter inside, and the optical loss is high. Full bonding means that the entire contact surface of the waveguide substrate 10 and the protective sheet 20 is seamlessly bonded using optical grade adhesive. The full bonding process can eliminate the air layer between the two and has excellent optical performance and strong protection.

[0049] For example, the diffractive waveguide also includes a light modulation layer 30. The proportion of visible light passing through the light modulation layer 30 in outdoor environments varies from 20% to 100%. In strong light environments, the visible light transmittance decreases to block strong light and achieve the function of sunglasses; in low light environments, the visible light transmittance increases to ensure clear vision. Long-wave ultraviolet rays in the long ultraviolet band are more harmful to human eyes and substrates. 80% to 99% of ultraviolet rays in this band can be absorbed by the light modulation layer 30, which can protect human eyes and extend the service life of the lens.

[0050] The diffractive waveguide proposed in this embodiment uses at least one waveguide substrate 10 and at least one protective sheet 20 to couple virtual image light into the waveguide. The light is then guided by a grating to propagate within the waveguide and finally transmitted to the user's eye. Combined with the light control layer 30, the transmittance of visible light is adjusted and ultraviolet rays are absorbed and protected. This effectively shields the user from strong outdoor light, preventing ultraviolet rays from damaging the eyes and equipment, and improving the environmental adaptability and service life of the diffractive waveguide.

[0051] For example, a diffractive waveguide may include a diffractive waveguide lens.

[0052] Optionally, the light-regulating layer 30 may include a color-changing layer and / or an anti-ultraviolet layer 33.

[0053] The color-changing layer includes a photochromic layer 31 and / or an electrochromic layer 32. The light-regulating layer 30 includes at least one of the photochromic layer 31, the electrochromic layer 32, and the UV-resistant layer 33.

[0054] The photochromic layer 31 refers to a material layer whose color or properties change due to variations in ambient light intensity. The photochromic layer 31 can be made of materials such as NCC#82, OP057, OP058, TW02, and TW10 to achieve the photochromic function. For example, taking NCC#82 as an example, when the NCC#82 content in the formulation is 3%-40%, it can achieve a maximum visible light transmittance of 99.8%, a minimum visible light transmittance of 60.0%, a visible light transmittance variation range of 30.0%, and an absorption rate of 80%-95% for the long ultraviolet (UV-A) band. When the NCC#82 content in the formulation is 40%-70%, it can achieve a maximum visible light transmittance of 98.0%, a minimum visible light transmittance of 20.0%, a visible light transmittance variation range of 70.0%, and an absorption rate of 95%-99% for the long ultraviolet band.

[0055] When energized, ions within the electrochromic layer 32 migrate, enabling faster adjustment of visible light transmittance. However, the electrochromic layer 32 lacks ultraviolet absorption capabilities and must be used in conjunction with other light-regulating layers 30 to achieve effective ultraviolet protection.

[0056] The UV protection layer 33 is a micro-grating structure that utilizes the diffraction and filtering properties of the grating to achieve UV protection. The UV protection layer 33 can reflect or scatter ultraviolet rays, reducing the transmittance of ultraviolet rays, while not affecting the transmission of visible light, thus ensuring clear image display.

[0057] Optional, Figure 2 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention, for reference. Figure 1 and Figure 2 The color-changing layer includes a photochromic layer 31 and / or an electrochromic layer 32; the color-changing layer (i.e., the photochromic layer 31 and / or the electrochromic layer 32) is located on the side of the protective sheet 20 away from the waveguide substrate 10; or, the color-changing layer (i.e., the photochromic layer 31 and / or the electrochromic layer 32) is located on the side of the waveguide substrate 10 away from the protective sheet 20.

[0058] In one example, refer to Figure 1 The color-changing layer includes a photochromic layer 31, which is located on the side of the protective sheet 20 away from the waveguide substrate 10, that is, the photochromic layer 31 is located on the upper surface of the protective sheet 20.

[0059] In one example, refer to Figure 2 The color-changing layer includes a photochromic layer 31, which is located on the side of the waveguide substrate 10 away from the protective sheet 20. That is, the photochromic layer 31 is located on the lower surface of the waveguide substrate 10.

[0060] In one example, the color-changing layer includes a photochromic layer 31 and an electrochromic layer 32. The photochromic layer 31 and the electrochromic layer 32, as a whole, can be located together on the side of the protective sheet 20 away from the waveguide substrate 10, or both can be located on the side of the waveguide substrate 10 away from the protective sheet 20. The positions of the photochromic layer 31 and the electrochromic layer 32 can be set according to requirements. For example, when the photochromic layer 31 and the electrochromic layer 32 are both located on the side of the protective sheet 20 away from the waveguide substrate 10, the photochromic layer 31 can be located between the electrochromic layer 32 and the protective sheet 20, or the electrochromic layer 32 can be located between the photochromic layer 31 and the protective sheet 20.

[0061] The color-changing layer may include a photochromic layer 31 and / or an electrochromic layer 32. This embodiment of the invention uses a photochromic layer 31 as an example for illustrative explanation. The protective sheet 20 has two surfaces: the inner surface is connected to the waveguide substrate 10 via frame bonding or full bonding, and the outer surface faces the external environment. Figure 1 As shown, a photochromic material coating can be applied to the outer surface of the protective sheet 20 away from the waveguide substrate 10 to form a photochromic layer 31. The photochromic layer 31 can directly receive external light intensity and effectively absorb ultraviolet light. The waveguide substrate 10 has two surfaces: the inner surface is connected to the protective sheet 20 via a frame or full lamination, while the outer surface faces the external environment. Figure 2 As shown, a photochromic material coating can be applied to the outer surface of the waveguide substrate 10 on the side away from the protective sheet 20, which simplifies the thickness of the protective sheet 20 while effectively absorbing ultraviolet rays.

[0062] Optional, Figure 3 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention. Figure 4 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention, for reference. Figure 3 and Figure 4 The color-changing layer includes a photochromic layer 31; the photochromic layer 31 and the protective sheet 20 form an integrated composite structure, the composite structure is used to achieve a visible light transmittance range of 20% to 100% and an absorption rate of 80% to 99% in the long ultraviolet band; or, the photochromic layer 31 and the waveguide substrate 10 form an integrated composite structure, the composite structure is used to achieve a visible light transmittance range of 20% to 100% and an absorption rate of 80% to 99% in the long ultraviolet band.

[0063] The color-changing layer may include a photochromic layer 31 and / or an electrochromic layer 32. This embodiment of the invention uses a photochromic layer 31 as an example for illustrative explanation. Figure 3 As shown, the color-changing layer and the protective film 20 form an integrated composite structure, meaning that photochromic materials are added during the production of the protective film 20; as Figure 4 As shown, the color-changing layer can also form an integrated composite structure with the waveguide substrate 10, that is, photochromic material is added during the production of the waveguide substrate 10. Both the waveguide substrate 10 and the protective sheet 20 can achieve low visible light transmittance in strong light environment and high visible light transmittance in weak light environment. While reducing strong light glare, it ensures clear imaging, and at the same time achieves a high absorption rate of 80% to 99% in the long ultraviolet band, protecting the human eye and equipment.

[0064] Optional, Figure 5 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention, for reference. Figure 5 The color-changing layer may include a photochromic layer 31 and / or an electrochromic layer 32. The color-changing layer (i.e., the photochromic layer 31 and / or the electrochromic layer 32) is embedded within the protective sheet 20; the thickness of the color-changing layer is less than the thickness of the protective sheet 20. The color-changing layer is used to achieve a visible light transmittance variation within the range of 20% to 100%, and an absorption rate of 80% to 99% in the long ultraviolet band. No color-changing material (including photochromic material and / or electrochromic material) is disposed within the thickness of the upper and lower portions of the protective sheet 20, while color-changing material is disposed within the thickness of the inner portion of the protective sheet 20.

[0065] Figure 6 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention, for reference. Figure 6The color-changing layer is embedded inside the waveguide substrate 10. The thickness of the color-changing layer (i.e., the photochromic layer 31 and / or the electrochromic layer 32) is less than the thickness of the waveguide substrate 10. The color-changing layer is used to achieve a visible light transmittance range of 20% to 100% and an absorption rate of 80% to 99% in the long ultraviolet band. No color-changing material (including photochromic material and / or electrochromic material) is disposed within the thickness of the upper and lower portions of the waveguide substrate 10, but color-changing material is disposed within the thickness of the inner portion of the waveguide substrate 10.

[0066] In summary, the color-changing layer can also be embedded in the inner intermediate layer of the protective sheet 20 or the waveguide substrate 10. Embedding the color-changing layer inside the protective sheet 20 or the waveguide substrate 10 can enhance the protective properties of the color-changing material and effectively shield it from strong outdoor light, preventing ultraviolet rays from damaging human eyes and equipment.

[0067] Optional, Figure 7 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention, for reference. Figure 7 The light modulation layer 30 also includes an anti-ultraviolet (UV) layer 33; when the photochromic layer (i.e., the photochromic layer 31 and / or the electrochromic layer 32) is located on the side of the protective sheet 20 away from the waveguide substrate 10, the UV-resistant layer 33 is located on the surface of the protective sheet 20 facing the waveguide substrate 10. In an example where the photochromic layer includes both the photochromic layer 31 and the UV-resistant layer 33, when the photochromic layer 31 is located on the side of the protective sheet 20 away from the waveguide substrate 10, the UV-resistant layer 33 is located on the surface of the protective sheet 20 facing the waveguide substrate 10. Exemplarily, the UV-resistant layer 33 includes an anti-UV grating.

[0068] For example, refer to Figure 7 The photochromic layer 31 and the UV-resistant layer 33 are located on both sides of the protective sheet 20 and are positioned opposite to each other about the protective sheet 20.

[0069] Figure 8 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention, for reference. Figure 8 When the photochromic layer (i.e., photochromic layer 31 and / or electrochromic layer 32) is located on the side of the waveguide substrate 10 away from the protective sheet 20, the UV-resistant layer 33 is located on the surface of the waveguide substrate 10 facing the protective sheet 20. In an example where the photochromic layer includes both the photochromic layer 31 and the UV-resistant layer 33, when the photochromic layer 31 is located on the side of the waveguide substrate 10 away from the protective sheet 20, the UV-resistant layer 33 is located on the surface of the waveguide substrate 10 facing the protective sheet 20. Exemplarily, refer to... Figure 8 The photochromic layer 31 and the UV-resistant layer 33 are located on both sides of the waveguide substrate 10 and are positioned opposite to the waveguide substrate 10.

[0070] The UV-resistant layer 33 reflects or scatters ultraviolet rays, reducing their transmittance. Combined with the photochromic layer 31 and / or the electrochromic layer 32, it provides better UV protection. This embodiment uses the combined use of the photochromic layer 31 and the UV-resistant layer 33 as an example. The UV-resistant layer 33 and the photochromic layer 31 are alternately arranged, such as... Figure 7 As shown, the photochromic layer 31 is located on the upper surface of the protective sheet 20, while the UV-resistant layer 33 is located on the lower surface of the protective sheet 20; Figure 8 As shown, the photochromic layer 31 is located on the lower surface of the waveguide substrate 10, while the UV-resistant layer 33 is located on the upper surface of the waveguide substrate 10. The UV-resistant layer 33, combined with the photochromic layer 31 and / or the electrochromic layer 32, can effectively shield against strong outdoor light, preventing UV damage to human eyes and equipment.

[0071] For example, refer to Figure 8 When the UV-resistant layer 33 is located on the surface of the waveguide substrate 10 facing the protective sheet 20, the grating region is also located on the surface of the waveguide substrate 10 facing the protective sheet 20. The UV-resistant layer 33 has a clearance area (e.g., an opening), and the grating region is located within the clearance area. That is, the UV-resistant layer 33 is located away from the grating region.

[0072] Optionally, in other embodiments not illustrated, when the photochromic layer 31 and / or the electrochromic layer 32 are located on the side of the protective sheet 20 away from the waveguide substrate 10, the UV-resistant layer 33 is located on the surface of the waveguide substrate 10; or, when the photochromic layer 31 and / or the electrochromic layer 32 are located on the side of the waveguide substrate 10 away from the protective sheet 20, the UV-resistant layer 33 is located on the surface of the protective sheet 20. That is, the photochromic layer 31 and / or the electrochromic layer 32 are disposed on one of the protective sheet 20 and the waveguide substrate 10, and correspondingly, the UV-resistant layer 33 is disposed on the other of the protective sheet 20 and the waveguide substrate 10.

[0073] Optional, Figure 9 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention. Figure 10 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention. Figure 11 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention. Figure 12 This is a schematic diagram of another diffractive waveguide structure proposed in this embodiment of the present invention, for reference. Figures 9 to 12The light control layer 30 includes an anti-ultraviolet layer 33; the anti-ultraviolet layer 33 is located on the surface of the protective sheet 20 away from the waveguide substrate 10; or, the anti-ultraviolet layer 33 is located on the surface of the protective sheet 20 facing the waveguide substrate 10; or, the anti-ultraviolet layer 33 is located on the surface of the waveguide substrate 10 facing the protective sheet 20; or, the anti-ultraviolet layer 33 is located on the surface of the waveguide substrate 10 away from the protective sheet 20.

[0074] For example, refer to Figures 9 to 12 The light control layer 30 includes an anti-ultraviolet layer 33. The visible light transmittance of the light control layer 30 is 90% to 99%, and the reflectivity of the light control layer 30 in the long ultraviolet band is 30% to 70%.

[0075] For example, refer to Figures 7 to 8 The light control layer 30 includes an anti-ultraviolet layer 33 and a color-changing layer. The visible light transmittance of the light control layer 30 varies in the range of 20% to 100%, and it achieves an absorption rate of 80% to 99% in the long ultraviolet band.

[0076] Among them, such as Figure 9 As shown, the UV-resistant layer 33 can be located on the outer surface of the protective sheet 20 to directly intercept ultraviolet rays incident on the diffraction waveguide; as Figure 10 As shown, the UV-resistant layer 33 can be located on the inner surface of the protective sheet 20 to reflect residual UV rays that have passed through the protective sheet 20; as Figure 11 As shown, the UV-resistant layer 33 can be located on the inner surface of the waveguide substrate 10 to specifically protect the optical functional areas of the waveguide substrate 10 and prevent ultraviolet rays from further damaging the diffraction performance of the waveguide substrate 10; as Figure 12 As shown, the UV-resistant layer 33 can be located on the outer surface of the waveguide substrate 10 to ultimately reflect residual ultraviolet rays that have passed through the entire diffraction waveguide structure, thus preventing ultraviolet rays from damaging the human eye.

[0077] Optionally, the UV-resistant layer 33 includes a UV-resistant grating structure that satisfies:

[0078]

[0079] Where D is the period of the UV-resistant grating structure. Let $\frac{ ... The refractive index of waveguide substrate 10 is given when the UV grating structure is located on the surface of the protective sheet. To protect the refractive index of sheet 20, For light wavelengths in the long ultraviolet band, The wavelength of light is in the visible light band.

[0080] in, The refractive index of air, Since the period of the UV-resistant layer 33 is approximately 1, it is less than the wavelength of light in the long ultraviolet band. This means the maximum period at which the UV-resistant layer 33 can provide UV protection is less than the wavelength of light in the long ultraviolet band. In this case, long-wave ultraviolet light incident on the UV-resistant layer 33 will undergo diffraction or scattering, and most of the long-wave ultraviolet light cannot penetrate the diffraction waveguide, thus achieving the function of UV protection. Because... ,therefore, The period of the UV-resistant layer 33 is greater than the wavelength of light in the long ultraviolet band divided by the refractive index of the protective film 20. In other words, the minimum period at which the UV-resistant layer 33 can achieve UV protection is greater than the wavelength of light in the long ultraviolet band divided by the refractive index of the protective film 20. Because... Based on the above conditions, the periodic range of the UV-resistant layer 33 can be determined as follows:

[0081]

[0082] When the periodic range of the UV-resistant layer 33 is within the above-mentioned range, that is At that time, the UV-resistant layer 33 can effectively absorb light in the long ultraviolet band, achieving the function of UV protection. Because... ,therefore, The period of the UV-resistant layer 33 is less than the wavelength of visible light divided by the refractive index of the protective film 20. In other words, the maximum period of the UV-resistant layer 33 that does not affect visible light is less than the wavelength of visible light divided by the refractive index of the protective film 20. This range ensures that when visible light is incident on the UV-resistant layer 33, the diffraction of visible light will not be blocked by the UV-resistant layer 33. That is, visible light can efficiently pass through the UV-resistant layer 33, thereby ensuring that visible light from AR virtual images and the real environment can pass through smoothly without affecting the user's visual experience.

[0083] Optional, Figure 13 This is a schematic diagram of a photochromic layer with partitioned configuration according to an embodiment of this utility model. (Refer to...) Figure 13 The color-changing layer includes a photochromic layer 31; the photochromic layer 31 includes multiple partitions A distributed sequentially from the center to the outside, the multiple partitions A include a first partition A1 and a second partition A2, the second partition A2 at least partially surrounds the first partition A1, and the content of photochromic material in the second partition A2 is greater than the content of photochromic material in the first partition A1.

[0084] The photochromic layer 31 includes multiple partitions A distributed sequentially from the center outwards. Partition A may include a first partition A1, a second partition A2, ..., an nth partition An. This embodiment of the invention uses the first partition A1 and the second partition A2 as an example for illustrative explanation. The first partition A1 is located in the central region of the photochromic layer 31, and the second partition A2 surrounds the first partition A1, i.e., it is located in the edge region of the photochromic layer 31. The content of photochromic material in the second partition A2 is greater than that in the first partition A1, meaning the visible light transmittance of the first partition A1 is greater than that of the second partition A2. The low content of photochromic material in the first partition A1 results in less absorption of virtual image light, ensuring high visible light transmittance within the common field of vision of the human eye and guaranteeing clear display of virtual images. The high content of photochromic material in the second partition A2 results in stronger absorption of strong edge light, ensuring effective protection against ultraviolet rays in sunlight at large angles and improving the environmental adaptability of the AR glasses.

[0085] Optionally, the color-changing layer includes a photochromic layer 31; the content of photochromic material in the photochromic layer 31 gradually increases from the center outwards.

[0086] In this process, the content of photochromic material in the photochromic layer 31 gradually increases from the center outwards, meaning that the photochromic material in the photochromic layer 31 has a gradient design. This gradient design ensures that the content of photochromic material in the central area of ​​the photochromic layer 31 is the lowest and the light transmittance is the highest, ensuring that the user's core field of vision can observe clear AR images and real scenes. As the center extends outwards, the content of photochromic material in the photochromic layer 31 gradually increases and the light transmittance gradually decreases. This reduces the stimulation of strong edge light on the human eye while ensuring clear imaging, thus improving the user experience.

[0087] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A diffractive optical waveguide, characterized in that, It includes at least one waveguide substrate and at least one protective sheet; the waveguide substrate contains at least one grating region; the protective sheet is located on the side of the waveguide substrate where the grating region is located. The diffractive waveguide also includes a light modulation layer; the light modulation layer is used to adjust the transmittance of visible light and to achieve UV resistance.

2. The diffractive waveguide according to claim 1, characterized in that, The light-regulating layer includes a color-changing layer and / or an anti-ultraviolet layer.

3. The diffractive waveguide according to claim 2, characterized in that, The color-changing layer includes a photochromic layer and / or an electrochromic layer; The color-changing layer is located on the side of the protective sheet away from the waveguide substrate; or, the color-changing layer is located on the side of the waveguide substrate away from the protective sheet.

4. The diffractive waveguide according to claim 2, characterized in that, The color-changing layer includes a photochromic layer; The photochromic layer and the protective sheet form an integrated composite structure. The composite structure is used to achieve a visible light transmittance range of 20% to 100% and an absorption rate of 80% to 99% in the long ultraviolet band. Alternatively, the photochromic layer and the waveguide substrate form an integrated composite structure, which is used to achieve visible light transmittance ranging from 20% to 100% and absorption rate of 80% to 99% in the long ultraviolet band.

5. The diffractive waveguide according to claim 2, characterized in that, The color-changing layer is embedded inside the protective sheet; the thickness of the color-changing layer is less than the thickness of the protective sheet, and the color-changing layer is used to achieve a visible light transmittance range of 20% to 100% and an absorption rate of 80% to 99% in the long ultraviolet band. Alternatively, the color-changing layer is embedded inside the waveguide substrate, and the thickness of the color-changing layer is less than the thickness of the waveguide substrate. The color-changing layer is used to achieve visible light transmittance ranging from 20% to 100% and absorption rate of 80% to 99% in the long ultraviolet band.

6. The diffractive waveguide according to claim 3, characterized in that, The light modulation layer also includes an anti-ultraviolet layer; When the color-changing layer is located on the side of the protective sheet away from the waveguide substrate, the UV-resistant layer is located on the surface of the protective sheet facing the waveguide substrate; or, the UV-resistant layer is located on the surface of the waveguide substrate. When the color-changing layer is located on the side of the waveguide substrate away from the protective sheet, the UV-resistant layer is located on the surface of the waveguide substrate facing the protective sheet; or, the UV-resistant layer is located on the surface of the protective sheet.

7. The diffractive waveguide according to any one of claims 2, 4, and 5, characterized in that, The light modulation layer includes the UV-resistant layer; The UV-resistant layer is located on the surface of the protective sheet on the side away from the waveguide substrate; Alternatively, the UV-resistant layer is located on the surface of the protective sheet on the side facing the waveguide substrate; Alternatively, the UV-resistant layer is located on the surface of the waveguide substrate facing the protective sheet; Alternatively, the UV-resistant layer may be located on the surface of the waveguide substrate on the side away from the protective sheet.

8. The diffractive waveguide according to claim 7, characterized in that, The UV-resistant layer includes a UV-resistant grating structure, satisfying the following: Wherein, D is the period of the UV-resistant grating structure. The refractive index of air, The refractive index of the protective sheet or the waveguide substrate. For long ultraviolet wavelengths, The wavelength of light is in the visible light band.

9. The diffractive waveguide according to claim 2, characterized in that, The color-changing layer includes a photochromic layer; The photochromic layer includes multiple partitions distributed sequentially from the center outwards. Each partition includes a first partition and a second partition. The second partition at least partially surrounds the first partition. The content of photochromic material in the second partition is greater than the content of photochromic material in the first partition.

10. The diffractive waveguide according to claim 2, characterized in that, The color-changing layer includes a photochromic layer; From the center of the photochromic layer outwards, the content of the photochromic material in the photochromic layer gradually increases.

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