Diffraction waveguide structure and near-to-eye display device

Abstract

The invention provides a diffraction waveguide structure and a near-to-eye display device. The diffraction waveguide structure comprises a first waveguide, a coupling-in grating and a first coupling-out grating, wherein the coupling-in grating and the first coupling-out grating are arranged on the same side of the first waveguide; the selective transmission film layer and the second coupling-out grating are arranged on the other side of the first waveguide; the coupling-out directions of the first coupling-out grating and the second coupling-out grating are the same. The selective transmission film layer can reflect first light and transmit second light, and the propagation angle of the first light in the first waveguide is larger than that of the second light in the first waveguide; the second coupling-out grating is used for coupling out the second light penetrating through the selective transmission film layer; the first coupling-out grating is used for coupling out the first light and the second light which are transmitted in the first waveguide, so that the coupling-out number of the second light is increased, the difference between the coupling-out number of the first light and the coupling-out number of the second light is reduced as much as possible, and the display effect is improved.

Description

Technical Field

[0001] The present application relates to the field of mold technology, and in particular to a diffraction waveguide structure and a near-eye display device. Background Art

[0002] Augmented Reality (AR) technology is a technology that combines virtual scenes with the real world. AR devices based on the diffraction waveguide solution have the advantages of thin and light products, high transmittance, and low mass production cost. Therefore, the diffraction waveguide solution is one of the mainstream solutions for AR devices.

[0003] In the conventional diffraction waveguide layout, the light emitted by the optical machine enters the waveguide through diffraction at the coupling-in grating and changes the propagation direction. The light that meets the total reflection condition will propagate along the waveguide to the transition grating. The function of the transition grating is to increase the exit pupil range. The light diverted by the transition grating propagates to the coupling-out grating, where it diffracts and leaves the waveguide and enters the human eye, forming an image on the retina.

[0004] However, diffraction waveguides are extremely sensitive to wavelength, which results in different diffraction efficiencies for different colors of light, and ultimately leads to poor color uniformity in full-color AR devices based on diffraction waveguides. After the pattern is transmitted, the ratio of RGB colors will change, affecting the visual effect. Summary of the invention

[0005] The present application provides a diffraction waveguide structure and a near-eye display device, which are used to improve the display effect of the near-eye display device.

[0006] In a first aspect, the present application provides a diffraction waveguide structure, the diffraction waveguide structure comprising a first waveguide, an in-coupling grating and a first out-coupling grating arranged on the same side of the first waveguide; further comprising a selective transmission film layer arranged on a side of the first waveguide away from the in-coupling grating; and a second out-coupling grating arranged on a side of the selective transmission film layer away from the first waveguide; Along the thickness direction of the first waveguide, the first outcoupling grating and the second outcoupling grating are arranged opposite to each other, and the outcoupling directions of the first outcoupling grating and the second outcoupling grating are the same; The selective transmission film layer can reflect the first light and transmit the second light, and the propagation angle of the first light in the first waveguide is greater than the propagation angle of the second light in the first waveguide; The second out-coupling grating is used for out-coupling the second light beam passing through the selective transmission film layer; the first out-coupling grating is used for out-coupling the first light beam and the second light beam propagating in the first waveguide.

[0007] In the above technical solution, different light rays are reflected and transmitted by a selectively transmitted film layer, so that the second light ray with a large propagation angle can be coupled out through the second coupling grating, thereby increasing the amount of second light ray coupled out, thereby minimizing the difference in the amount of first light ray and second light ray coupled out, thereby improving the display effect.

[0008] In a specific embodiment, the invention further comprises a second waveguide stacked with the first waveguide; wherein the selective transmission film layer is sandwiched between the first waveguide and the second waveguide; and the thickness of the first waveguide is greater than the thickness of the second waveguide; The second outcoupling grating is arranged on a side of the second waveguide facing away from the first waveguide.

[0009] In a specific embodiment, the thickness of the second waveguide is greater than 0.1 mm.

[0010] In a specific possible implementation, along the length direction of the first waveguide, the length of the selective transmission film layer is greater than or equal to the length of the first outcoupling grating and the second outcoupling grating.

[0011] In a specific possible implementation manner, along the length direction of the first waveguide, the length of the selective transmission film layer is equal to the length of the first waveguide, and two ends of the selective transmission film layer are flush with two ends of the first waveguide.

[0012] In a specific implementation manner, along the length direction of the first waveguide, the lengths of the first outcoupling grating and the second outcoupling grating are equal, and two ends of the first outcoupling grating are flush with two ends of the second outcoupling grating.

[0013] In a specific possible implementation manner, the first outcoupling grating is a transmissive grating; and the second outcoupling grating is a reflective grating.

[0014] In a specific implementation manner, the first out-coupling grating and the in-coupling grating are an integrated structure with the first waveguide; The second outcoupling grating and the second waveguide are an integrated structure.

[0015] In a specific embodiment, the selective transmission film layer is a Bragg reflector.

[0016] In a second aspect, a near-eye display device is provided, the near-eye display device comprising a display device and any of the above-mentioned diffractive waveguide structures; wherein: The light emitted from the display device couples the coupling grating into the first waveguide.

[0017] In the above technical solution, different light rays are reflected and transmitted by a selectively transmitted film layer, so that the second light ray with a large propagation angle can be coupled out through the second coupling grating, thereby increasing the amount of second light ray coupled out, thereby minimizing the difference in the amount of first light ray and second light ray coupled out, thereby improving the display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of an application scenario of the diffraction waveguide structure provided in an embodiment of the present application; Figure 2 A schematic diagram of light propagation in a diffraction waveguide structure in the prior art; Figure 3 A schematic structural diagram of a diffraction waveguide structure provided in an embodiment of the present application; Figure 4 A graph showing a corresponding relationship between the thickness ratio of the first waveguide and the second waveguide and the outcoupling amounts of the first light and the second light provided in an embodiment of the present application; Figure 5 A schematic diagram of another diffraction waveguide structure provided in an embodiment of the present application; Figure 6 It is a simulation schematic diagram of a diffraction waveguide structure in the prior art; Figure 7 A simulation schematic diagram of a diffraction waveguide structure provided in an embodiment of the present application; Figure 8 A simulation schematic diagram of another diffraction waveguide structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings.

[0020] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of this specification should be understood by people with ordinary skills in the field to which this disclosure belongs. The "first", "second" and similar words used in one or more embodiments of this specification do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] To facilitate understanding of the optical device provided in the embodiment of the present application, its application scenario is first described. The display device provided in the embodiment of the present application is applied to different near-eye display systems such as AR (Augmented Reality, enhanced display technology) or VR (Virtual Reality, virtual display technology) to realize virtual display. However, the current near-eye display system generally has the problem of uneven light when the light is coupled out of the light guide, which affects the customer's viewing.

[0022] like Figure 1 As shown in Figure 1 A schematic diagram of an application scenario of an optical device in the prior art is shown. The prior optical device includes a light guide 1, a light coupling device 2, a light coupling device 3 and a light generator 9. Among them, the light generator 9 is used to emit light for displaying an image. The light coupling device 2 is used to couple the light emitted by the light generator 9 into the light guide 1. The light guide 1 is used to propagate light, and it has two oppositely arranged total internal reflection surfaces. The light in the light guide 1 can propagate light through total internal reflection of the total internal reflection surfaces. The light coupling device 3 is used to couple the light in the light guide 1 into the user's eyes, so that the user can observe the image displayed by the light generator.

[0023] For reference Figure 2 As shown in FIG. 1 , when the light is coupled into the waveguide 100 through the coupling grating 200 and propagates, the propagation angles of light of different wavelengths are different. The propagation angle refers to the angle formed by the light with the surface of the waveguide when propagating in the waveguide. Figure 2 The solid line shown in FIG. 1 is the first light 2000, and the dotted line is the second light 1000. When the first light 2000 and the second light 1000 propagate in the waveguide 100, the propagation angle of the first light 2000 is α, and the propagation angle of the second light 1000 is β, and the propagation angle α of the first light 2000 is greater than the propagation angle β of the second light 1000. Therefore, the first light 2000 is reflected more times in the waveguide 100, and the interval between two adjacent reflection positions on the same surface of the waveguide 100 is shorter, while the second light 1000 has a smaller propagation angle, so the second light 1000 is reflected less times in the waveguide 100, and the interval between two adjacent reflection positions on the same surface of the waveguide 100 is larger. When the first light 2000 and the second light 1000 propagate to the outcoupling grating 300, it can be intuitively seen that the outcoupling amount of the first light 2000 is greater than the outcoupling amount of the second light 1000, resulting in a large difference in the outcoupling amount of light of different wavelengths, affecting the viewing effect of the user. The first light 2000 and the second light 1000 can be lights of different colors. For example, the first light 2000 is blue light and the second light 1000 is red light.

[0024] To this end, the embodiment of the present application provides a diffraction waveguide structure to improve the viewing effect of users. Detailed description is given below in conjunction with specific drawings and embodiments.

[0025] refer to Figure 3 As shown, Figure 3 A schematic diagram of a diffraction waveguide structure provided in an embodiment of the present application is shown. The diffraction waveguide structure provided in an embodiment of the present application mainly includes a first waveguide 10, an input grating 20, a first output grating 30, a second output grating 60, and a selective transmission film layer 50. Among them, the first waveguide 10 is used to propagate light, so as to propagate the light coupled in by the input grating 20 to the output grating (the first output grating 30 and the second output grating 60). The selective transmission film layer 50 is used to selectively transmit and reflect different light. In an embodiment of the present application, the selective transmission film layer is used to reflect the first light 2000 and transmit the second light 1000. So that the first light 2000 and the second light 1000 are emitted along different output paths.

[0026] In a specific configuration, the coupling-in grating 20 and the first coupling-out grating 30 are disposed on the same side of the first waveguide 10. In a specific arrangement, the coupling-in grating 20 and the coupling-out grating may be located at opposite ends of the first waveguide 10. The light (including the first light 2000 and the second light 1000) coupled into the first waveguide 10 by the coupling-in grating 20 may propagate through the first waveguide 10 to the first coupling-out grating 30 and be coupled out. The functions and positions of the coupling-in grating 20 and the first coupling-out grating 30 are the same as those of the existing coupling-in grating 20, and will not be described in detail herein.

[0027] In the embodiment of the present application, the propagation angle of the first light 2000 in the first waveguide 10 is greater than the propagation angle of the second light 1000 in the first waveguide 10, so that the number of total reflections of the first light 2000 in the first waveguide 10 is greater than the number of total reflections of the second light 1000 in the first waveguide 10. Therefore, when the light is coupled out only through the first coupling grating 30, the coupling amount of the first light 2000 is greater than the coupling amount of the second light 1000.

[0028] In order to improve the outcoupling effect of the diffraction waveguide structure on light, the diffraction waveguide structure provided in the embodiment of the present application increases the outcoupling amount of the second light 1000 through the cooperation of the selective transmission film layer 50 and the second outcoupling grating 60 .

[0029] In the specific configuration, the selective transmission film layer 50 and the second outcoupling grating 60 are both located on the same side of the first waveguide 10 away from the incoupling grating 20. The selective transmission film layer 50 is disposed on the side of the first waveguide 10 away from the incoupling grating 20, and the second outcoupling grating 60 is disposed on the side of the selective transmission film layer 50 away from the first waveguide 10, that is, the second outcoupling grating 60, the selective transmission film layer 50, and the first waveguide 10 are stacked, and the selective transmission film layer 50 is located between the second outcoupling grating 60 and the first waveguide 10. The second outcoupling grating 60 is used to couple out the second light 1000 that passes through the selective transmission film layer 50.

[0030] In addition, when the second outcoupling grating 60 is specifically arranged, the second outcoupling grating 60 is arranged opposite to the first outcoupling grating 30 along the thickness direction of the first waveguide 10. Moreover, the outcoupling directions of the first outcoupling grating 30 and the second outcoupling grating 60 are the same.

[0031] Continue to refer Figure 3 As shown, for ease of understanding, two opposite surfaces of the first waveguide 10 are defined as a first surface 11 and a second surface 12. The first out-coupling grating 30 and the in-coupling grating 20 are both disposed on the first surface 11, the selective transmission film layer 50 is disposed on the second surface 12, and the second out-coupling grating 60 is disposed on the selective transmission film layer 50. When the first light 2000 and the second light 1000 are incident from the in-coupling grating 20 into the first waveguide 10, the first light 2000 and the second light 1000 are totally reflected and propagated between the first surface 11 and the second surface 12. When the first light 2000 and the second light 1000 are irradiated to the selective transmission film layer 50, the first light 2000 is reflected by the selective transmission film layer 50 and continues to propagate in the first waveguide 10, while when the second light 1000 passes through the selective transmission film layer 50, the second light 1000 is transmitted through the selective transmission film layer 50 and propagates to the second outcoupling grating 60, and the second outcoupling grating 60 couples out the second light 1000. Since the first outcoupling grating 30 and the second outcoupling grating 60 are located opposite to each other, the second light 1000 coupled out by the second outcoupling grating 60 passes through the selective transmission film layer 50, the first waveguide 10 and the first outcoupling grating 30 and then is emitted. In addition, when both the first light 2000 and the second light 1000 are irradiated to the first outcoupling grating 30, the first outcoupling grating 30 couples out the first light 2000 and the second light 1000.

[0032] like Figure 3 As shown in FIG. 1 , the number of first light rays 2000 coupled out through the first coupling grating 30 is 4, the number of second light rays 1000 coupled out through the first coupling grating 30 is 2, and the number of second light rays 1000 coupled out through the second coupling grating 60 is 1. Figure 3It can be seen that in the embodiment of the present application, the second light 1000 is added with a coupling-out grating (second coupling-out grating 60 ), so as to increase the coupling-out amount of the second light 1000 and reduce the difference between the light coupled out of the first light 2000 and the second light 1000 .

[0033] It can be seen from the above description that in the diffraction waveguide structure provided in the embodiment of the present application, the selective transmission film layer 50 is set to reflect and transmit different light rays, so that the second light 1000 with a large propagation angle can be coupled out through the second coupling grating 60, thereby increasing the number of second light rays 1000 coupled out, thereby minimizing the difference in the number of first light rays 2000 and second light rays 1000 coupled out, thereby improving the display effect.

[0034] Specifically, different arrangements may be used when arranging the selective transmission film layer 50 and the second outcoupling grating 60. For ease of understanding, they are described in detail below with reference to specific drawings.

[0035] The diffraction waveguide structure provided in the embodiment of the present application may further include a second waveguide 40. The first waveguide 10 and the second waveguide 40 have the same material and function, and are used to propagate the first light 2000 and the second light 1000 by total reflection.

[0036] In the specific arrangement, the second waveguide 40 is stacked with the first waveguide 10, and the second waveguide 40 is located on the side of the first waveguide 10 away from the coupling-in grating 20. The selective transmission film layer 50 is sandwiched between the first waveguide 10 and the second waveguide 40, and the second coupling-out grating 60 is arranged on the side of the second waveguide 40 away from the first waveguide 10. When the light propagates, the first light 2000 is totally reflected only in the first waveguide 10 by the reflection of the selective transmission film layer 50. For the second light 1000, since the selective transmission film layer 50 can transmit the second light 1000, the first waveguide 10 and the second waveguide 40 can be regarded as one waveguide, and the second light 1000 is totally reflected in the first waveguide 10 and the second waveguide 40. In the above scheme, although the second waveguide 40 is added, the arrangement of the second coupling-out grating 60 is facilitated.

[0037] In this structure, when the incident angle of the light entering the first waveguide 10 is θ1, the propagation angle after passing through the coupling grating 20 becomes , the interval between the two outcouplings of the first light 2000 is , the interval between the two outcouplings of the second light 1000 is ; where λ 1 is the wavelength of the incident light, T is the grating period, n 1 、n 2 are the refractive indices of air and the first waveguide 10, d 1is the rear end of the first waveguide 10, d 2 is the thickness of the second waveguide 40 .

[0038] When the second waveguide 40 has the same thickness as the first waveguide 10, the outcoupling times of the second light 1000 are the same as those of the diffraction waveguide structure in the prior art. When the second waveguide is thicker than the first waveguide, the outcoupling times of the second light 1000 begin to decrease. Therefore, in order to increase the outcoupling times, the upper limit of the thickness of the second waveguide 40 is less than the thickness of the first waveguide 10, and the thinner the second waveguide 40 is, the more outcoupling times of the second light 1000 are.

[0039] It can be seen from the above description that the second waveguide 40 increases the path length of the second light 1000 during total reflection. Therefore, when the first waveguide 10 and the second waveguide 40 are specifically set, the thickness of the first waveguide 10 is greater than the thickness of the second waveguide 40, so that the added second waveguide 40 can minimize the impact on the second light 1000, ensuring that the number of second light rays 1000 increased by coupling out through the second coupling grating 60 is greater than the number of second light rays 1000 reduced due to the increase in the total reflection path of the second light 1000.

[0040] When the first waveguide 10 and the second waveguide 40 are specifically arranged, the thickness of the first waveguide 10 and the second waveguide 40 directly affects the outcoupling amount of the first light 2000 and the second light 1000, as shown in FIG. Figure 4 As shown, Figure 4 FIG. 4 is a schematic diagram showing the relationship between the ratio of the thickness of the first waveguide 10 and the second waveguide 40 and the ratio of the outcoupling amount of the first light 2000 to the second light 1000. Figure 4 It can be seen that the smaller the thickness of the second waveguide 40 is, the greater the outcoupling amount of the second light 1000 is. Therefore, in the specific setting, the second waveguide 40 is made as small as possible under the premise of satisfying the processing. However, it should be understood that in the embodiment of the present application, the thickness of the second waveguide 40 is greater than 0.1 mm to ensure that the second waveguide 40 meets the minimum size for processing and facilitates the processing and preparation of the second waveguide 40.

[0041] As an example, the selective transmission film layer 50 provided in the embodiment of the present application is a Bragg reflector, which can select the first light 2000 and the second light 1000, reflect the first light 2000, and transmit the second light 1000.

[0042] In addition, as for the length of the selective transmission film layer 50, along the length direction of the first waveguide 10, the length of the selective transmission film layer 50 is greater than or equal to the length of the first outcoupling grating 30 and the second outcoupling grating 60. This ensures that when the first light 2000 and the second light 1000 irradiate the first outcoupling grating 30 and the second outcoupling grating 60, the first light 2000 and the second light 1000 can be screened by the selective transmission film layer 50.

[0043] In an implementable solution, along the length direction of the first waveguide 10, the length of the selective transmission film layer 50 is equal to the length of the first waveguide 10, and both ends of the selective transmission film layer 50 are flush with both ends of the first waveguide 10. In this state, the first light 2000 propagates only in the first waveguide 10, and the second light 1000 propagates in both the first waveguide 10 and the second waveguide 40.

[0044] Of course, in addition to the above examples, the length of the selective transmission film layer 50 may be smaller than the length of the first waveguide 10. When this method is adopted, it is equivalent to increasing the propagation path of the first light 2000, reducing the number of total reflections in the first waveguide 10, reducing the outcoupling amount of the first light 2000, and to a certain extent, reducing the difference in the outcoupling amount of the first light 2000 and the second light 1000.

[0045] In an optional solution, along the length direction of the first waveguide 10, the lengths of the first outcoupling grating 30 and the second outcoupling grating 60 are equal, and the two ends of the first outcoupling grating 30 are flush with the two ends of the second outcoupling grating 60. That is, the first outcoupling grating 30 and the second outcoupling grating 60 are completely aligned in the thickness of the first waveguide 10. When this method is adopted, on the one hand, it is convenient to fix the first outcoupling grating 30 and the second outcoupling grating 60 on the first waveguide 10 and the second waveguide 40. In addition, when the first outcoupling grating 30 and the second outcoupling grating 60 of the same length are adopted, it can also be ensured that the second light 1000 coupled out by the second grating can be emitted through the first outcoupling grating 30, thereby improving the outcoupling effect of the second light 1000.

[0046] The first outcoupling grating 30 and the second outcoupling grating 60 provided in the embodiment of the present application may adopt different types of outcoupling gratings. Exemplarily, the first outcoupling grating 30 is a transmissive grating, and the second outcoupling grating 60 is a reflective grating. This ensures that the outcoupling directions of the first outcoupling grating 30 and the second outcoupling grating 60 are consistent, and ensures that the second light 1000 coupled out by the second outcoupling grating 60 can be emitted after passing through the first outcoupling grating 30.

[0047] When the first out-coupling grating 30 and the second out-coupling grating 60 are specifically prepared, the first out-coupling grating 30 and the in-coupling grating 20 are integrated with the first waveguide 10, and the second out-coupling grating 60 is integrated with the second waveguide 40. That is, when specifically set, the first out-coupling grating 30 is directly prepared on the first waveguide 10, and the second out-coupling grating 60 is directly prepared on the second out-coupling grating 60. When this structure is adopted, on the one hand, the structural strength between the various parts of the diffraction waveguide structure is improved, and on the other hand, the interface of the first light 2000 and the second light 1000 during propagation can be reduced, thereby improving the effect of light propagation.

[0048] In a variant embodiment, Figure 5 As shown, the diffraction waveguide structure provided in the embodiment of the present application may not include the second waveguide 40, that is, the second outcoupling grating 60 is directly connected to the selective transmission film layer 50. When this structure is adopted, the selective transmission film layer 50 is directly disposed on the second surface 12 of the first waveguide 10. In addition, the length of the selective transmission film layer 50 is the same as the length of the second outcoupling grating 60, and the ends of the two are aligned. When the second light 1000 propagates in the diffraction waveguide structure, the propagation path of the second light 1000 is basically the same as that of the diffraction waveguide structure in the prior art, but the outcoupling amount of the second light 1000 is equivalent to doubled, which can effectively improve the outcoupling amount of the second light 1000, reduce the difference in the outcoupling amount of the first light 2000 and the second light 1000, and improve the display effect of the near-eye display device.

[0049] To facilitate understanding of the effect of the diffraction waveguide structure provided in the embodiment of the present application, the structure in which the diffraction waveguide structure includes a first waveguide 10 and a second waveguide 40 is taken as an example, and it is simulated and compared with the diffraction waveguide structure in the prior art. Among them, the parameters of the diffraction waveguide structure provided in the embodiment of the present application are as follows: the thickness of the first waveguide 10 is 0.8 mm, and the refractive index is 2.0; the thickness of the second waveguide 40 is 0.3 mm, and the refractive index is 2.0. The thickness of the waveguide in the prior art is 0.8 mm, and the refractive index is 2.0. For light with a field of view angle of 30° in the horizontal direction, the relationship between the outcoupling times of the first light ray and the second light ray and the incident angle is as follows: Figure 6 and Figure 7 Reference Figure 6 It can be seen that by Figure 6 It can be seen that the average outcoupling times of the first light 2000 in the diffractive waveguide structure in the prior art is 2.05 times the average outcoupling times of the second light 1000. Figure 7 As shown, the average outcoupling times of the first light 2000 in the diffraction waveguide structure provided in the embodiment of the present application is 1.41 times the average outcoupling times of the second light 1000.

[0050] For reference Figure 8 As shown, Figure 8 The figure shows the outcoupling times of the first light 2000 and the second light 1000 when a thinner second waveguide 40 is used. When the thickness of the second waveguide 40 is 0.1 mm, the average outcoupling times of the first light 2000 is 1.15 times the average outcoupling times of the second light 1000.

[0051] It can be seen from the above description that in the diffraction waveguide structure provided in the embodiment of the present application, by adopting a thinner second waveguide or not adopting a second waveguide, the outcoupling amount of the second light can be increased, the difference between the outcoupling amounts of the first light and the second light can be improved, and the display effect of the near-eye display device can be improved.

[0052] The embodiment of the present application further provides a near-eye display device, which includes a display device and any of the above-mentioned diffractive waveguide structures; wherein the light emitted by the display device couples the coupling grating 20 into the first waveguide 10. The diffractive waveguide structure can refer to any of the above-mentioned diffractive waveguide structures.

[0053] In the above technical solution, the selective transmission film layer 50 is set to reflect and transmit different light rays, so that the second light 1000 with a large propagation angle can be coupled out through the second coupling grating 60, thereby increasing the number of second light rays 1000 coupled out, thereby minimizing the difference in the number of first light rays 2000 and second light rays 1000 coupled out, thereby improving the display effect.

[0054] One or more embodiments of this specification are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification should be included in the scope of protection of this disclosure.

[0055] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A diffractive waveguide structure, characterized in that: The invention comprises a first waveguide, an in-coupling grating and a first out-coupling grating arranged on the same side of the first waveguide; a selective transmission film layer arranged on a side of the first waveguide away from the in-coupling grating; and a second out-coupling grating arranged on a side of the selective transmission film layer away from the first waveguide; Along the thickness direction of the first waveguide, the first outcoupling grating and the second outcoupling grating are arranged opposite to each other, and the outcoupling directions of the first outcoupling grating and the second outcoupling grating are the same; The selective transmission film layer can reflect the first light and transmit the second light, and the propagation angle of the first light in the first waveguide is greater than the propagation angle of the second light in the first waveguide; The second out-coupling grating is used for out-coupling the second light beam passing through the selective transmission film layer; the first out-coupling grating is used for out-coupling the first light beam and the second light beam propagating in the first waveguide.

2. The diffractive waveguide structure according to claim 1, characterized in that: Also includes a second waveguide stacked with the first waveguide; wherein the selective transmission film layer is sandwiched between the first waveguide and the second waveguide; and the thickness of the first waveguide is greater than the thickness of the second waveguide; The second outcoupling grating is arranged on a side of the second waveguide facing away from the first waveguide.

3. The diffractive waveguide structure according to claim 2, characterized in that: The thickness of the second waveguide is greater than 0.1 mm.

4. The diffractive waveguide structure according to claim 2, characterized in that: Along the length direction of the first waveguide, the length of the selective transmission film layer is greater than or equal to the length of the first outcoupling grating and the second outcoupling grating.

5. The diffractive waveguide structure according to claim 4, characterized in that: Along the length direction of the first waveguide, the length of the selective transmission film layer is equal to the length of the first waveguide, and two ends of the selective transmission film layer are flush with two ends of the first waveguide.

6. The diffractive waveguide structure according to claim 2, characterized in that: Along the length direction of the first waveguide, the lengths of the first outcoupling grating and the second outcoupling grating are equal, and two ends of the first outcoupling grating are flush with two ends of the second outcoupling grating.

7. The diffractive waveguide structure according to claim 2, characterized in that: The first outcoupling grating is a transmissive grating; the second outcoupling grating is a reflective grating.

8. The diffractive waveguide structure according to any one of claims 2 to 7, characterized in that: The first out-coupling grating and the in-coupling grating are an integrated structure with the first waveguide; The second outcoupling grating and the second waveguide are an integrated structure.

9. The diffractive waveguide structure according to claim 8, characterized in that: The selective transmission film layer is a Bragg reflector.

10. A near-eye display device, characterized in that: A display device and a diffraction waveguide structure as claimed in any one of claims 1 to 9; wherein: The light emitted from the display device couples the coupling grating into the first waveguide.

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