Near-to-eye display optical waveguide and near-to-eye display equipment

Abstract

The invention provides a near-to-eye display optical waveguide and near-to-eye display equipment. The near-to-eye display optical waveguide comprises at least one waveguide substrate and optical gratings arranged on the waveguide substrate, the optical gratings comprise a pre-coupling-in optical grating and at least one group of diffraction optical gratings, and the diffraction optical gratings comprise a coupling-in optical grating and a coupling-out optical grating; the coupling-in grating is located behind the pre-coupling-in grating in the transmission direction of the light beams, and the coupling-in grating is arranged close to the coupling-out grating relative to the pre-coupling-in grating in the direction of the center connecting line of the coupling-in grating and the coupling-out grating; wherein the pre-coupling-in grating is used for diffracting a light beam to the coupling-in grating, the coupling-in grating is used for coupling the light beam diffracted by the pre-coupling-in grating into the waveguide substrate and transmitting the light beam to the coupling-out grating along the waveguide substrate, and the coupling-out grating is used for coupling the light beam out of the waveguide substrate. Coupling efficiency is high, energy utilization rate is high, and processing cost is low.

Description

Technical Field

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

[0002] In recent years, the development of information display technology is no longer limited to flat panel displays, but is more focused on the integrated interaction between users, natural environment and displayed information. As a new generation of interactive display technology, virtual reality (VR) and augmented reality (AR) technologies provide people with a new way to perceive the world. Among them, AR technology uses a near-eye display device with a see-through vision to superimpose the virtual image emitted by the display with the real world, which greatly enriches the new acquisition efficiency of people's observation of the world and further improves the perception dimension of the user's interaction with the real world. With the rapid progress of near-eye display optical technology and the further improvement of user experience, AR display has shown its strong potential competitiveness in health detection, education, engineering design, advanced manufacturing, environmental protection, and game entertainment. Surface relief grating (SRG) optical waveguide technology is considered to be one of the most promising solutions for realizing near-eye display optical waveguides and related equipment, and has gradually demonstrated its excellent commercial value. Unlike refractive index modulated diffraction waveguide devices, SRG technology directly prepares micro-nano structures on the surface of the waveguide, which means that SRG waveguides can be mass-produced at low cost through nanoimprinting technology. Moreover, by utilizing the large refractive index difference between the SRG waveguide and the air, the surface micro-nano structure only needs a structural depth of hundreds of nanometers to achieve a certain diffraction efficiency. Some SRG surface relief grating (SRG) design schemes with large asymmetric shapes have been proposed in the related art. These schemes are complex in design and consume a lot of computing resources for the optimization of the initial structural parameters, which is very unfavorable to the improvement of the iteration speed of the SRG waveguide design scheme; in addition, they are difficult to process and have high mass production costs. Summary of the invention

[0003] The present application provides an improved near-eye display optical waveguide and a near-eye display device.

[0004] The present application provides a near-eye display optical waveguide, comprising: at least one waveguide substrate and a grating arranged on the waveguide substrate, the grating comprising a pre-coupling grating and at least one group of diffraction gratings, the diffraction grating comprising a coupling-in grating and a coupling-out grating; in the transmission direction along the light beam, the coupling-in grating is located behind the pre-coupling grating, and in the direction of the center line connecting the coupling-in grating and the coupling-out grating, the coupling-in grating is arranged close to the coupling-out grating relative to the pre-coupling grating; wherein the pre-coupling grating is used to diffract the light beam to the coupling-in grating, the coupling-in grating is used to couple the light beam diffracted by the pre-coupling grating into the waveguide substrate, and transmit it along the waveguide substrate to the coupling-out grating, and the coupling-out grating is used to couple the light beam out of the waveguide substrate.

[0005] Optionally, the pre-coupling grating and the coupling grating each provide a single grating vector, the coupling-out grating provides at least one grating vector, the sum of the grating vectors provided by the pre-coupling grating and the coupling-in grating is equal in magnitude to a grating vector or a combination of multiple grating vectors provided by the coupling-out grating, and has an opposite direction; wherein the magnitude of the grating vector is equal to 2π multiplied by the inverse of the grating period of the grating, and the direction of the grating vector is perpendicular to the grating period arrangement direction.

[0006] Optionally, the near-eye display optical waveguide includes a single layer of the waveguide substrate; the grating includes a group of the diffraction gratings, a group of the diffraction gratings includes one of the coupling-in gratings and one of the coupling-out gratings; the pre-coupling grating and the coupling-in grating are located on different surfaces of the waveguide substrate, and the coupling-out grating is located on any surface of the waveguide substrate.

[0007] Optionally, the near-eye display optical waveguide includes multiple layers of the waveguide substrate; the grating includes multiple groups of the diffraction gratings, each group of the diffraction gratings includes one coupling-in grating and one coupling-out grating; the pre-coupling grating is arranged on the waveguide substrate located at the top of the multiple layers of the waveguide substrate, and the multiple coupling-in gratings and multiple coupling-out gratings of the multiple groups of diffraction gratings are arranged on one of the layers of the waveguide substrate located below the top of the multiple layers of the waveguide substrate; wherein, in the direction of transmission along the light beam, the pre-coupling grating is located above the multiple groups of diffraction gratings and on any surface of the waveguide substrate at the top; the coupling-in grating and the coupling-out grating of each group of the diffraction gratings are located on the same layer of the waveguide substrate and are respectively located on the same surface or different surfaces of the same layer of the waveguide substrate.

[0008] Optionally, in the direction of the center line connecting the coupling-in grating and the coupling-out grating, a plurality of the coupling-in gratings are arranged close to the coupling-out grating relative to the pre-coupling grating.

[0009] Optionally, the coupling-in grating which is farther away from the pre-coupling grating is arranged closer to the coupling-out grating.

[0010] Optionally, the farther the coupling grating is from the pre-coupling grating, the larger the area of ​​the coupling grating is.

[0011] Optionally, the coupling-in grating and the coupling-out grating of a group of the diffraction gratings located on the same layer of the waveguide substrate both satisfy that the sum of the grating vectors provided by the pre-coupling grating and the coupling-in grating is equal in size to a grating vector or a combination of multiple grating vectors provided by the coupling-out grating, and have opposite directions.

[0012] Optionally, the thickness of the waveguide substrate at the top is smaller than the thickness of any layer of the waveguide substrate below the top.

[0013] Optionally, the thickness of the multiple layers of the waveguide substrate located below the top is equal.

[0014] Optionally, the pre-coupling grating and the coupling grating are located between two waveguide substrates in a stacked arrangement, and are spaced apart and not in contact in a stacking direction.

[0015] Optionally, two stacked layers of the waveguide substrates are connected by micro-bead glue, and the assembly size range of the micro-bead glue is 5 μm to 500 μm.

[0016] Optionally, the diffraction grating also includes a turning grating, and the coupling-in grating, the turning grating and the coupling-out grating are located on the same layer of the waveguide substrate, and in the direction of the center line connecting the coupling-in grating and the coupling-out grating, the turning grating is located between the coupling-in grating and the coupling-out grating.

[0017] Optionally, the near-eye display optical waveguide includes a single layer of the waveguide substrate; the grating includes a group of the diffraction gratings, a group of the diffraction gratings includes one of the coupling-in gratings, one of the turning gratings and one of the coupling-out gratings; the turning grating provides a plurality of grating vectors; the sum of the grating vectors provided by the pre-coupling grating and the coupling-in grating is equal in size to a grating vector or a combination of multiple grating vectors provided by the turning grating and the coupling-out grating, and has an opposite direction.

[0018] Optionally, the near-eye display optical waveguide includes multiple layers of the waveguide substrate; the grating includes multiple groups of the diffraction gratings, each group of the diffraction gratings includes one of the coupling-in gratings, one of the turning gratings and one of the coupling-out gratings; the turning gratings provide multiple grating vectors; the coupling-in gratings, the coupling-out gratings and the turning gratings located on the same layer of the waveguide substrate all satisfy that the sum of the grating vectors provided by the pre-coupling grating and the coupling-in grating is equal to the size of a grating vector or a combination of multiple grating vectors provided by the turning grating and the coupling-out grating, and are opposite in direction.

[0019] Optionally, the pre-coupling grating, the coupling grating and the out-coupling grating are all sub-wavelength optical structures;

[0020] Optionally, the sub-wavelength optical structure is a regular area surrounded by straight edges, or surrounded by arc edges, or surrounded by straight edges and arc edges.

[0021] Optionally, the surface of the sub-wavelength optical structure is provided with an optical coating; the material of the optical coating or the coating is one or a combination of at least two of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium oxide, and zirconium oxide.

[0022] Optionally, the material of the sub-wavelength optical structure includes at least one or more combinations of optical glass, optical resin and optical glass material.

[0023] Optionally, the refractive index of the sub-wavelength optical structure is the same as or different from the refractive index of the waveguide substrate.

[0024] Optionally, the pre-coupled grating includes at least one of a one-dimensional straight-tooth grating, a two-dimensional straight-tooth grating, a blazed grating or a tilted grating.

[0025] Optionally, the coupling-in grating includes at least one of a one-dimensional straight-tooth grating, a two-dimensional straight-tooth grating, a blazed grating or a tilted grating.

[0026] Optionally, the pre-coupled grating includes at least one of a photonic crystal, a metamaterial or a surface.

[0027] Optionally, the coupling-in grating comprises at least one of a photonic crystal, a metamaterial or a surface.

[0028] Optionally, the outcoupling grating comprises at least one of a photonic crystal, a metamaterial or a surface.

[0029] Optionally, the outcoupling grating includes a columnar structure, a conical structure, or a terraced structure.

[0030] Optionally, the near-eye display optical waveguide includes multiple layers of the waveguide substrate, and the refractive indexes of any two layers of the waveguide substrate are the same or different.

[0031] Optionally, the surface of the waveguide substrate is a plane or a curved surface, wherein the curved surface is a convex surface or a concave surface or an aspherical surface or a free-form surface.

[0032] Optionally, the surface of the waveguide substrate is provided with an optical coating; the material of the optical coating or the coating is one or a combination of at least two of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium oxide, and zirconium oxide.

[0033] The present application also provides a near-eye display device, comprising:

[0034] projection equipment; and

[0035] In the near-eye display light waveguide described in any one of the above embodiments, the projection device is arranged on one side of the near-eye display light waveguide; the projection device is used to emit a light beam containing image information to the pre-coupled grating of the near-eye display light waveguide.

[0036] The near-eye display optical waveguide and near-eye display device of the embodiments of the present application. The near-eye display optical waveguide is provided with a pre-coupling grating, the coupling grating is arranged behind the pre-coupling grating, and the coupling grating is arranged close to the coupling grating relative to the pre-coupling grating. The pre-coupling grating and the coupling grating together provide an angle for diffracting the outgoing light to meet the total reflection condition. Neither of them needs to provide a larger grating vector, that is, a larger grating period. The diffraction grating with a larger grating period can provide higher diffraction efficiency and capacity utilization, and its processing difficulty, processing time and processing cost are also low. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The diagram is a schematic structural diagram of an embodiment in which the near-eye display optical waveguide of the near-eye display device of the present application has a single-layer waveguide substrate.

[0038] Figure 2 Shown Figure 1 The near-eye display optical waveguide of the near-eye display device shown has a top-view structural schematic diagram of a single-layer waveguide substrate.

[0039] Figure 3 Shown Figure 2 The near-eye display optical waveguide of the near-eye display device shown has a bottom-up structural schematic diagram of a single-layer waveguide substrate.

[0040] Figure 4 Shown Figure 1 The near-eye display optical waveguide of the near-eye display device shown is a schematic structural diagram of another embodiment having a single-layer waveguide substrate.

[0041] Figure 5 Shown Figure 1 The near-eye display optical waveguide of the near-eye display device shown has a wave vector analysis diagram of a single-layer waveguide substrate.

[0042] Figure 6 Shown Figure 1 The structure of an embodiment of a pre-coupling grating for a near-eye display optical waveguide is shown.

[0043] Figure 7 Shown Figure 1 The structure of an embodiment of an in-coupling grating of a near-eye display optical waveguide is shown.

[0044] Figure 8 Shown Figure 1 A schematic structural diagram of an embodiment of an out-coupling grating of a near-eye display optical waveguide is shown.

[0045] Fig. 9 The diagram is a schematic structural diagram of an embodiment in which the near-eye display optical waveguide of the near-eye display device of the present application has two layers of waveguide substrates.

[0046] Fig.10 Shown Fig. 9 The near-eye display optical waveguide of the near-eye display device shown is a schematic structural diagram of another embodiment having two layers of waveguide substrates.

[0047] Fig.11 Shown Fig. 9 The structure diagram of another embodiment of a near-eye display optical waveguide of a near-eye display device shown has two layers of waveguide substrates.

[0048] Fig.12 The diagram is a schematic structural diagram of an embodiment in which the near-eye display optical waveguide of the near-eye display device of the present application has a three-layer waveguide substrate.

[0049] Fig.13 Shown Fig.12 A wave vector analysis diagram of an embodiment of a second waveguide substrate of a near-eye display optical waveguide of a near-eye display device is shown.

[0050] Fig.14 Shown Fig.12 A wave vector analysis diagram of an embodiment of a third waveguide substrate of a near-eye display optical waveguide of a near-eye display device is shown.

[0051] Fig.15 The diagram is a schematic structural diagram of an embodiment in which the near-eye display optical waveguide of the near-eye display device of the present application has a four-layer waveguide substrate.

[0052] Fig.16The figure shows a comparison of the energy distribution of the near-eye display device in the present application and the related art within the two-dimensional field of view distribution range. DETAILED DESCRIPTION

[0053] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0054] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. Unless otherwise defined, the technical terms or scientific terms used in this application should be understood by people with ordinary skills in the field to which this application belongs. The words "first", "second" and similar words used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantitative limit, but indicate that there is at least one. "Multiple" or "several" means at least two. Unless otherwise specified, words such as "front", "rear", "lower" and / or "upper" are only for the convenience of explanation and are not limited to a position or a spatial orientation. Words such as "include" or "comprise" mean that the elements or objects appearing in front of "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude the remaining elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, and can include electrical connections, whether direct or indirect.

[0055] As used in the specification and appended claims of this application, the singular forms "a", "said" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0056] The present application provides a near-eye display optical waveguide and a near-eye display device. The near-eye display optical waveguide includes: at least one waveguide substrate and a grating arranged on the waveguide substrate, the grating includes a pre-coupling grating and at least one group of diffraction gratings arranged on the waveguide substrate, the diffraction grating includes a coupling grating and an out-coupling grating; in the transmission direction along the light beam, the coupling grating is located behind the pre-coupling grating, and in the direction of the center line connecting the coupling grating and the out-coupling grating, the coupling grating is arranged close to the out-coupling grating relative to the pre-coupling grating; wherein the pre-coupling grating is used to diffract the light beam to the coupling grating, the coupling grating is used to couple the light beam diffracted by the pre-coupling grating into the waveguide substrate, and transmit it along the waveguide substrate to the out-coupling grating, and the out-coupling grating is used to couple the light beam out of the waveguide substrate.

[0057] The near-eye display optical waveguide and near-eye display device of the embodiments of the present application. The near-eye display optical waveguide is provided with a pre-coupling grating, the coupling grating is arranged behind the pre-coupling grating, and the coupling grating is arranged close to the coupling grating relative to the pre-coupling grating. The pre-coupling grating and the coupling grating together provide an angle for diffracting the outgoing light to meet the total reflection condition. Neither of them needs to provide a larger grating vector, that is, a larger grating period. The diffraction grating with a larger grating period can provide higher diffraction efficiency and capacity utilization, and its processing difficulty, processing time and processing cost are also low.

[0058] The present application provides a near-eye display optical waveguide and a near-eye display device. The near-eye display optical waveguide and the near-eye display device of the present application are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0059] In some embodiments, the near-eye display device 10 includes one of augmented reality glasses, augmented reality helmets, head-mounted displays, and projection display devices. Any of the above near-eye display devices 10 not only meets the user's wearable usage requirements, but also meets the requirements of lightweight and miniaturization.

[0060] Figure 1 It is a schematic structural diagram of an embodiment in which the near-eye display optical waveguide 200 of the near-eye display device 10 of the present application has a single-layer waveguide substrate 201 . Figure 2 Shown Figure 1 The near-eye display optical waveguide 200 of the near-eye display device 10 shown is a schematic top view of the structure having a single-layer waveguide substrate 201 .

[0061] Figure 3 Shown Figure 2 The near-eye display optical waveguide 200 of the near-eye display device 10 shown in the figure has a bottom-up structural schematic diagram of a single-layer waveguide substrate 201. Figures 1 to 3As shown, the near-eye display device 10 includes a projection device 100 and a near-eye display optical waveguide 200, and the projection device 100 is arranged on one side of the near-eye display optical waveguide 200. Near-eye display refers to displaying an image source in a near-eye field of view of a human eye through a light source device, a light guide device, a display panel and other devices. The projection device 100 is used to emit a light beam containing image information to the near-eye display optical waveguide 200. The near-eye display optical waveguide 200 is used to couple the light beam containing image information emitted by the projection device 100 into and transmit and couple out the light beam to the human eye 300. In some embodiments, the projection device 100 may be a projection optical machine or a projector.

[0062] In some embodiments, the near-eye display optical waveguide 200 includes at least one waveguide substrate 201 and a grating 202 disposed on the waveguide substrate 201, wherein the grating 202 includes a pre-coupling grating 2021 and at least one set of diffraction gratings, wherein the diffraction grating includes a coupling-in grating 2022 and an out-coupling grating 2023. The projection device 100 is used to emit a light beam containing image information to the pre-coupling grating 2021 of the near-eye display optical waveguide 200. The pre-coupling grating 2021 is used to diffract the light beam to the coupling-in grating 2022, and the coupling-in grating 2022 is used to couple the light beam diffracted by the pre-coupling grating 2021 into the waveguide substrate 201, and transmit the light beam along the waveguide substrate 201 to the out-coupling grating 2023, and the out-coupling grating 2023 is used to couple the light beam out of the waveguide substrate 201 and enter the human eye 300.

[0063] In some embodiments, the coupling-in grating 2022 and the coupling-out grating 2023 are located on the same side or different sides of the waveguide substrate 201. Figures 1 to 3In the illustrated embodiment, the near-eye display optical waveguide 200 includes a single-layer waveguide substrate 201. The projection device 100 and the human eye 300 are located on the same side of the near-eye display optical waveguide 200. The positive direction of the X-axis refers to the direction extending in the X-axis direction. The projection device 100 and the pre-coupling grating 2021 are located on the same side of the waveguide substrate 201. The projection device 100 and the coupling grating 2022 are located on different sides of the waveguide substrate 201. The coupling grating 2022 and the out-coupling grating 2023 are located on different sides of the waveguide substrate 201. The projection device 100 and the human eye 300 are distributed in the positive direction of the X-axis, and the pre-coupling grating 2021 and the coupling grating 2022 are arranged in the positive direction of the X-axis relative to the out-coupling grating 2023. The projection device 100 emits a light beam containing image information to the pre-coupling grating 2021 of the near-eye display optical waveguide 200. The pre-coupling grating 2021 is used to diffract the light beam to the coupling grating 2022, and the coupling grating 2022 is used to couple the light beam diffracted by the pre-coupling grating 2021 into the waveguide substrate 201, and transmit it in the waveguide substrate 201 along the positive direction of the X axis by total reflection without loss. When the light beam is transmitted to the coupling-out grating 2023, the two-dimensional exit pupil expansion is performed under the action of the coupling-out grating 2023, and the coupled-out light beam is transmitted into the human eye 300. In this process, the two-dimensional exit pupil expansion means that the display pupil range of the light beam emitted by the image source is expanded in the two-dimensional direction after being transmitted in the near-eye display optical waveguide 200.

[0064] Figure 4 Shown Figure 1 The schematic diagram of the structure of another embodiment of the near-eye display optical waveguide of the near-eye display device shown has a single-layer waveguide substrate. Figure 4 In the embodiment shown, Figure 1 The embodiment shown is similar, and the main difference is that the coupling-in grating 2022 and the coupling-out grating 2023 are located on the same side of the waveguide substrate 201. The projection device 100 emits a light beam containing image information to the pre-coupling grating 2021 of the near-eye display optical waveguide 200. The pre-coupling grating 2021 is used to diffract the light beam to the coupling-in grating 2022, and the coupling-in grating 2022 is used to couple the light beam diffracted by the pre-coupling grating 2021 into the waveguide substrate 201, and transmit it in the waveguide substrate 201 along the positive direction of the X-axis by total reflection without loss. When the light beam is transmitted to the coupling-out grating 2023, the two-dimensional exit pupil expansion is performed under the action of the coupling-out grating 2023, and the coupled-out light beam is transmitted into the human eye 300.

[0065] exist Figures 1 to 4In the illustrated embodiment, in the transmission direction of the light beam, the coupling-in grating 2022 is located behind the pre-coupling grating 2021, and in the direction of the center line of the coupling-in grating 2022 and the out-coupling grating 2023, the coupling-in grating 2022 is arranged close to the out-coupling grating 2023 relative to the pre-coupling grating 2021. In the present embodiment, the projection device 100 emits a light beam containing image information, and the transmission direction of the light beam may be a direction perpendicular to the waveguide substrate 201. The center line direction of the coupling-in grating 2022 and the out-coupling grating 2023 may be the positive direction of the X-axis. The light beam containing image information emitted by the projection device 100 is first modulated by the pre-coupling grating 2021. After diffraction by the pre-coupling grating 2021, the central field light beam is deflected in the positive direction of the X-axis. The light beam modulated by the pre-coupling grating 2021 is then propagated to the coupling grating 2022. After the second diffraction by the coupling grating 2022, all the field light beams meet the total reflection condition in the waveguide substrate 201 and propagate in the waveguide substrate 201 in the direction of the coupling grating 2023 in a total reflection manner. In the positive direction of the X-axis, the coupling grating 2022 is arranged close to the coupling grating 2023 relative to the pre-coupling grating 2021, so that the light beam deflected after diffraction by the pre-coupling grating 2021 is propagated to the coupling grating 2022 as much as possible to reduce loss.

[0066] The near-eye display optical waveguide 200 of the near-eye display device 10 of the present embodiment is provided with a pre-coupling grating 2021, and the coupling grating 2022 is arranged behind the pre-coupling grating 2021, and the coupling grating 2022 is arranged close to the coupling grating 2023 relative to the pre-coupling grating 2021. The pre-coupling grating 2021 and the coupling grating 2022 jointly provide an angle for diffracting the outgoing light to satisfy the total reflection condition. Both do not need to provide a larger grating vector, that is, have a larger grating period. The diffraction grating with a larger grating period can provide higher diffraction efficiency and capacity utilization, and its processing difficulty, processing time and processing cost are also low.

[0067] Figure 5 Shown Figure 1 The near-eye display optical waveguide 200 of the near-eye display device 10 shown has a wave vector analysis diagram of a single-layer waveguide substrate 201 . Figure 6 Shown Figure 1 The structure schematic diagram of an embodiment of a pre-coupling grating 2021 of a near-eye display optical waveguide 200 is shown. Figure 7 Shown Figure 1 The structure of an embodiment of the coupling-in grating 2022 of the near-eye display optical waveguide 200 is shown. Figure 8 Shown Figure 1 FIG. 2 is a schematic diagram of a structure of an embodiment of an outcoupling grating 2023 of a near-eye display optical waveguide 200. Figures 1 to 8As shown, the pre-coupling grating 2021 and the coupling grating 2022 both provide a single grating vector. The pre-coupling grating 2021 has a single grating vector. The coupling grating 2022 has a single grating vector. The coupling-out grating 2023 provides at least one grating vector. The coupling-out grating 2023 has one or more grating vectors. The sum of the grating vectors provided by the pre-coupling grating 2021 and the coupling-in grating 2022 is equal in magnitude to a grating vector or a combination of multiple grating vectors provided by the coupling-out grating 2023, and has an opposite direction. The magnitude of the grating vector is equal to 2π times the inverse of the grating period of the grating, and the direction of the grating vector is perpendicular to the grating period arrangement direction.

[0068] exist Figure 5 In the illustrated embodiment, the pre-coupling grating 2021, the coupling grating 2022 and the coupling-out grating 2023 form a first wave vector circle 203 in the waveguide substrate 201. The first wave vector circle 203 includes a first wave vector inner circle 2031 and a first wave vector outer circle 2032. The radius of the first wave vector inner circle 2031 is 1.00, indicating that the waveguide substrate 201 is in an air environment with a refractive index of about 1.00. The radius of the first wave vector outer circle 2032 is 1.90, indicating that the refractive index of the waveguide substrate 201 is 1.90. The first wave vector circle 203 includes an incident light field of view / an outgoing light field of view 2033, a pre-coupling modulation field of view 2034, a coupling-in modulation field of view 2035 and a coupling-out turning field of view 2036.

[0069] exist Figure 5 In the illustrated embodiment, the incident light field of view 2033 is represented by a dotted rectangular frame at the center of the first wave vector circle 203. After the modulation effect of the pre-coupling grating 2021, the incident light field of view 2033 moves along the positive direction of the X-axis, and the moving distance is the wave vector k_pre of the pre-coupling grating. It should be noted that the pre-coupling modulated field of view 2034 after modulation by the pre-coupling grating 2021 must be located inside the first wave vector inner circle 2031. Afterwards, the light beam modulated by the pre-coupling grating 2021 continues to be incident on the coupling grating 2022. After the second modulation effect of the coupling grating 2022, the field of view area continues to move along the positive direction of the X-axis to the coupling modulated field of view 2035, and the moving distance is the wave vector k_in of the coupling grating 2022. It should be noted that the coupled modulated field of view 2035 after the second modulation by the coupled grating 2022 is located within the first wave vector outer circle 2032 and outside the first wave vector inner circle 2031. At this time, the light beams in all fields of view meet the total reflection condition and can be transmitted losslessly in the waveguide substrate 201.

[0070] When the light beam is transmitted to the outcoupling grating 2023, a two-dimensional exit pupil expansion is achieved and the light beam transmitted by total reflection in the waveguide substrate 201 is coupled out to the air and captured by the human eye 300. Since the outcoupling grating 2023 is a two-dimensional grating, the light beam in the waveguide substrate 201 can be coupled out of the waveguide substrate 201 via two main wave vector paths and enter the human eye 300. The first outcoupling path is to directly couple out via the wave vector k_out_1 to reach the output light field of view 2033, and the second outcoupling path is to first reach the outcoupling turning field of view 2036 via the wave vector k_out_21, and then reach the output light field of view 2033 via the wave vector k_out_22. Regardless of whether the light beam transmitted in the outcoupling region is coupled out via the first outcoupling path or the second outcoupling path, since the near-eye display optical waveguide 200 provided in this embodiment requires that the incident light field / the outgoing light field 2033 must completely overlap, the sum of the grating vectors of the pre-coupled grating 2021 and the coupled grating 2022 is equal in magnitude to the grating vector of the outcoupling grating 2023 and has an opposite direction, that is,

[0071]

[0072] At this time, the sum of the overall grating vectors of the near-eye display optical waveguide 200 is 0, which meets the wave vector requirement of the near-eye display optical waveguide 200.

[0073] In some embodiments, the pre-coupled grating 2021 includes at least one of a one-dimensional straight tooth grating, a two-dimensional straight tooth grating, a blazed grating, or a tilted grating. Figure 6 In the embodiment shown, the pre-coupled grating 2021 may be a one-dimensional straight tooth grating. The grating period of the pre-coupled grating 2021 is represented by Figure 6 In some embodiments, the coupling grating 2022 includes at least one of a one-dimensional straight tooth grating, a two-dimensional straight tooth grating, a blazed grating, or a tilted grating. Figure 7 In the embodiment shown, the coupling-in grating 2022 may be a one-dimensional straight tooth grating. The grating period of the coupling-in grating 2022 is represented by Figure 7 In the present embodiment, the grating period of the one-dimensional straight tooth grating of the pre-coupled grating 2021 is slightly larger than the grating period of the one-dimensional straight tooth grating of the coupled grating 2022. In some embodiments, the coupling-out grating 2023 includes a columnar structure, a cone structure, or a terrace structure. Figure 8 In the embodiment shown, the outcoupling grating 2023 comprises a two-dimensional straight grating of a rhombus column array. The rhombus column array is arranged in a two-dimensional hexagonal lattice, unfolded in the X-Y plane, and the ratio of the period in the X-axis direction to the period in the Y-axis direction is The X-axis direction intersects and is perpendicular to the Y-axis direction.

[0074] Compared with the conventional two-grating near-eye display optical waveguide 200 of coupling-in grating 2022 and coupling-out grating 2023, since coupling-in grating 2022 needs to provide a larger wave vector to directly move the grating of the overall field of view from incident light field of view 2033 to coupling-in modulation field of view 2035, coupling-in grating 2022 needs to provide a larger grating vector, which means a smaller grating period. In this embodiment, pre-coupling grating 2021 and coupling-in grating 2022 jointly provide a method for diffracting the outgoing light of projection device 100 to an angle that satisfies the total reflection condition, and neither of them needs to provide a larger grating vector, which means a larger grating period. A diffraction grating with a larger grating period can provide a higher diffraction efficiency, and its processing difficulty, processing time and processing cost will also be significantly reduced. Therefore, the near-eye display device 10 prepared by using the near-eye display optical waveguide 200 of this embodiment can have a higher energy utilization rate and better cost economy.

[0075] exist Figures 1 to 4 In the illustrated embodiment, the near-eye display optical waveguide 200 includes a single-layer waveguide substrate 201. The grating 202 includes a group of diffraction gratings, and the group of diffraction gratings includes a coupling grating 2022 and a coupling grating 2023. The pre-coupling grating 2021 and the coupling grating 2022 are located on different surfaces of the waveguide substrate 201, and the coupling grating 2023 is located on any surface of the waveguide substrate 201. The waveguide substrate 201 includes a first surface 2011 and a second surface 2012 that are arranged opposite to each other. The projection device 100 and the human eye 300 are located on one side of the first surface 2011. Figures 1 to 3 In the illustrated embodiment, the pre-coupling grating 2021 and the out-coupling grating 2023 are disposed on the first surface 2011. The coupling grating 2022 is disposed on the second surface 2012. Figure 4 In the embodiment shown, the pre-coupling grating 2021 is disposed on the first surface 2011. The coupling grating 2022 and the coupling-out grating 2023 are disposed on the second surface 2012. The arrangement is simple and reduces the difficulty of processing.

[0076] In some embodiments, the pre-coupling grating 2021, the coupling grating 2022 and the coupling-out grating 2023 are all sub-wavelength optical structures. In some embodiments, the sub-wavelength optical structure is a regular area surrounded by straight edges, or surrounded by arc edges, or surrounded by straight edges and arc edges, for example, it can be a rectangle, a pentagon, a hexagon or a circle. The sub-wavelength optical structure can have the same geometric shape and size, or different geometric shapes and sizes. With such a setting, the responsiveness of the light beam can be flexibly adjusted to improve the uniformity of the field of view.

[0077] In some embodiments, the surface of the sub-wavelength optical structure is provided with an optical coating or coating. In some embodiments, the coating or coating material may be a metal material, a dielectric material and / or a composite material composed of a metal and a dielectric. The material of the optical coating or coating is one or a combination of at least two of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium oxide, and zirconium oxide, and the thickness of the optical film or coating of each material is generally less than the working wavelength of the near-eye display optical waveguide 200. In this way, the diffraction efficiency can be controlled and the energy utilization rate can be improved by coating or setting the coating, and the ratio of light energy transmitted and reflected into the human eye 300 can also be effectively changed.

[0078] In some embodiments, the material of the sub-wavelength optical structure includes at least one or more combinations of optical glass, optical resin and optical glass material, and the refractive index thereof is between 1.40 and 2.30. In this way, the uniformity of the field of view can be flexibly adjusted.

[0079] In some embodiments, there is a filling medium between two adjacent sub-wavelength optical structures, and the refractive index of the filling medium is between 1.40 and 2.30. The filling medium can be a continuous air or inert gas structure, and its refractive index is near 1.00. The filling medium can also be a liquid with a refractive index slightly greater than 1.00. The refractive index value of the gap position of two adjacent sub-wavelength optical structures is different from the refractive index value of the sub-wavelength optical structure. The sub-wavelength optical structure array and / or its gap position is a sub-wavelength medium structure with surface relief characteristics, which can be prepared on the surface of the waveguide substrate 201 with high precision, low cost and large area through a nano-imprinting process. In this way, the diffraction efficiency can be controlled and the energy utilization rate can be improved, and the ratio of light energy transmitted and reflected into the human eye 300 can also be effectively changed.

[0080] In some embodiments, the sub-wavelength optical structure may have a height distribution, and its height value is generally between 10nm and 1000nm. In some embodiments, the height range of the sub-wavelength optical structure is 10nm or 50nm or 100nm or 150nm or 200nm or 250nm or 300nm or 350nm or 400nm or 450nm or 500nm or 550nm or 600nm or 650nm or 700nm or 750nm or 800nm ​​or 850nm or 900nm or 950nm or 1000nm. When the height of the sub-wavelength optical structure is in the range of 10nm to 1000nm, the function of two-dimensional exit pupil expansion can be achieved.

[0081] In some embodiments, the sub-wavelength optical structure may have a distribution of refractive index values. The refractive index of the sub-wavelength optical structure may be the same as or different from the refractive index of the waveguide substrate 201. In some embodiments, the refractive indexes of the pre-coupling grating 2021, the coupling grating 2022, and the coupling-out grating 2023 may be the same or different. The refractive index values ​​of the sub-wavelength optical structure at different coordinate positions in a specific diffraction region of the sub-wavelength optical structure may be the same or different, and may have a specific functional relationship with the plane coordinate position. In the present embodiment, the refractive indexes of the pre-coupling grating 2021, the coupling grating 2022, and the coupling-out grating 2023 are the same, and are all 1.90. Such an arrangement can further reduce the mass production manufacturing cost.

[0082] In some embodiments, the pre-coupling grating 2021 includes at least one of a photonic crystal, a metamaterial, or a surface. In some embodiments, the coupling-in grating 2022 includes at least one of a photonic crystal, a metamaterial, or a surface. In some embodiments, the coupling-out grating 2023 includes at least one of a photonic crystal, a metamaterial, or a surface. By selecting appropriate materials, the function of two-dimensional exit pupil expansion can be achieved.

[0083] In some embodiments, the surface of the waveguide substrate 201 is a plane or a curved surface, wherein the curved surface is a convex surface or a concave surface or an aspherical surface or a free-form surface. In some embodiments, the waveguide substrate 201 is a plane lens. In some other embodiments, the waveguide substrate 201 may be a convex mirror, a concave mirror, an aspherical lens or a free-form lens, or a combination of the above lenses. In some embodiments, the waveguide substrate 201 may have a refractive index value distribution, and its refractive index value may be between 1.40 and 2.30. The material of the waveguide substrate 201 may be one or a combination of optical glass, optical resin and optical glass tree materials. In some embodiments, the surface of the waveguide substrate 201 is provided with an optical coating. The material of the optical coating or coating is one or a combination of at least two of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium oxide, and zirconium oxide. The thickness of the optical film or coating of each material is generally less than the working wavelength of the near-eye display optical waveguide 200. In this way, the diffraction efficiency can be controlled and the energy utilization rate can be improved by coating or setting a coating, and the ratio of light energy transmitted and reflected into the human eye 300 can be effectively changed. In some embodiments, the waveguide substrate 201 can have a variety of geometric configurations, which are not limited in this application.

[0084] In the processing technology of the optical waveguide with surface relief grating, the grating 202 is prepared on the waveguide substrate 201 by nanoimprinting process. Nanoimprinting can only be prepared on one side of the waveguide substrate 201, and double-sided nanoimprinting often requires more expensive imprinting equipment and more complicated imprinting process. Therefore, the process cost of the solution of arranging the pre-coupled grating 2021 and the coupled grating 2022 on two surfaces of the same layer of waveguide substrate 201 is high. Therefore, in this embodiment, a multi-layer (for example, two layers or more) waveguide substrate 201 is arranged, and the pre-coupled grating 2021 is prepared on one surface of a waveguide substrate 201, and the coupled grating 2022 and the coupled-out grating 2023 are prepared on one surface of another waveguide substrate 201. With such a configuration, the multi-layer waveguide substrate 201 can be prepared by a single-sided imprinting process, and its processing technology is simpler and the processing cost is also lower. After the multiple waveguide substrates 201 are all embossed, they are assembled by gluing with micro-bead glue to form an overall near-eye display optical waveguide 200 .

[0085] In some embodiments, the near-eye display optical waveguide 200 includes a multilayer waveguide substrate 201. The near-eye display optical waveguide 200 includes two or more layers of waveguide substrates 201. The grating 202 includes multiple groups of diffraction gratings. Each group of diffraction gratings includes a coupling-in grating 2022 and a coupling-out grating 2023. The multiple groups of diffraction gratings include multiple coupling-in gratings 2022 and multiple coupling-out gratings 2023. The pre-coupling grating 2021 is disposed in the waveguide substrate 201 located at the top of the multilayer waveguide substrate 201, and the multiple coupling-in gratings 2022 and multiple coupling-out gratings 2023 of the multiple groups of diffraction gratings are disposed in one of the layers of the waveguide substrate 201 located below the top of the multilayer waveguide substrate 201. In the direction of light beam transmission, the pre-coupling grating 2021 is located above the multiple groups of diffraction gratings (multiple coupling gratings 2022 and multiple coupling gratings 2023) and on any surface of the top waveguide substrate 201. The coupling grating 2022 and coupling grating 2023 of each group of diffraction gratings are located on the same layer of waveguide substrate 201 and are respectively located on the same surface or different surfaces of the same layer of waveguide substrate 201. In some embodiments, the coupling grating 2022 and coupling grating 2023 of a group of diffraction gratings located on the same layer of waveguide substrate 201 satisfy that the sum of the grating vectors provided by the pre-coupling grating 2021 and the coupling grating 2022 is equal to the combination of one grating vector or multiple grating vectors provided by the coupling grating 2023 and the direction is opposite. With such a configuration, the near-eye display optical waveguide 200 has a high coupling efficiency for the light beam, a high energy utilization rate, a simple structure, and a simple processing technology.

[0086] In some embodiments, the thickness of the waveguide substrate 201 at the top is less than the thickness of any layer of the waveguide substrate 201 below the top. This arrangement can reduce costs and reduce the weight of the entire device. In some embodiments, the thickness of the multiple layers of waveguide substrates 201 below the top is equal. This arrangement facilitates batch processing.

[0087] In some embodiments, in the direction of the center line of the coupling-in grating 2022 and the coupling-out grating 2023, the plurality of coupling-in gratings 2022 are arranged close to the coupling-out grating 2023 relative to the pre-coupling grating 2021. The center line direction of the coupling-in grating 2022 and the coupling-out grating 2023 may be the positive direction of the X-axis. In the positive direction of the X-axis, the plurality of coupling-in gratings 2022 are arranged close to the coupling-out grating 2023 relative to the pre-coupling grating 2021, so that the light beam deflected after diffraction by the pre-coupling grating 2021 is propagated to the plurality of coupling-in gratings 2022 as much as possible, thereby reducing light loss.

[0088] In some embodiments, the coupling grating 2022 that is farther from the pre-coupling grating 2021 is arranged closer to the coupling grating 2023. In this way, the coupling efficiency and energy utilization rate are improved. In some embodiments, the area of ​​the coupling grating 2022 that is farther from the pre-coupling grating 2021 is larger. In this way, the coupling efficiency and energy utilization rate are improved.

[0089] In some embodiments, the refractive indexes of any two layers of the waveguide substrate 201 of the multilayer waveguide substrate 201 are the same or different. In some embodiments, the refractive indexes of any two layers of the waveguide substrate 201 of the multilayer waveguide substrate 201 are the same. In other embodiments, the refractive indexes of any two layers of the waveguide substrate 201 of the multilayer waveguide substrate 201 are different. In this way, the diffraction efficiency can be flexibly controlled and the energy utilization rate can be improved, and the ratio of the light energy transmitted and reflected into the human eye 300 can also be effectively changed.

[0090] In some embodiments, the pre-coupled grating 2021 and the coupled grating 2022 are located between two stacked waveguide substrates 201, and are spaced apart and not in contact in the direction of the stack. Such a configuration is conducive to the transmission of light. In some embodiments, the two stacked waveguide substrates 201 are connected by microbead glue 204, and the assembly size range of the microbead glue 204 can be 5μm to 500μm. The two stacked waveguide substrates 201 are connected by microbead glue 204, and the assembly method is simple and the process cost is low. In some embodiments, the assembly scale control mechanism of the microbead glue 204 can be a spherical structure, and its size can be 5μm or 10μm or 15μm or 20μm or 25μm or 30μm or 40μm or 45μm or 50μm or 55μm or 60μm or 65μm or 70μm or 75μm or 80μm or 85μm or 90μm or 95μm or 100μm, or 150μm or 200μm or 250μm or 300μm or 350μm or 400μm or 450μm or 500μm. When the assembly size of the microbead glue 204 is set appropriately, the two layers of waveguide substrates arranged in the stacking direction can be spaced apart and not in contact, which is conducive to the crosstalk-free transmission of light.

[0091] Fig. 9 The structure diagram of an embodiment of the near-eye display optical waveguide 200 of the near-eye display device 10 of the present application having two layers of waveguide substrate 201 is shown. Fig. 9 In the illustrated embodiment, the near-eye display optical waveguide 200 includes a two-layer waveguide substrate 201. The two-layer waveguide substrate 201 includes a first waveguide substrate 201A and a second waveguide substrate 201B. The first waveguide substrate 201A is located above the second waveguide substrate 201B. The first waveguide substrate 201A includes a first surface 2011A and a second surface 2012A that are oppositely disposed. The first surface 2011A may be the upper surface of the first waveguide substrate 201A, and the second surface 2012A may be the lower bottom surface of the first waveguide substrate 201A. The second waveguide substrate 201B includes a third surface 2011B and a fourth surface 2012B that are oppositely disposed. The third surface 2011B may be the upper surface of the second waveguide substrate 201B, and the fourth surface 2012B may be the lower surface of the second waveguide substrate 201B.

[0092] exist Fig. 9In the illustrated embodiment, the first waveguide substrate 201A and the second waveguide substrate 201B are fixed together by a microbead glue 204 disposed between the second surface 2012A and the third surface 2011B. In the near-eye display optical waveguide 200, a pre-coupling grating 2021 and a group of diffraction gratings (one coupling grating 2022 and one coupling grating 2023) are disposed on different waveguide substrates 201. The coupling grating 2022 and the coupling grating 2023 of the same group of diffraction gratings are disposed on the same surface of the same waveguide substrate 201. Specifically, the pre-coupling grating 2021 is disposed on the first surface 2011A of the first waveguide substrate 201A, and the coupling grating 2022 and the coupling grating 2023 are disposed on the third surface 2011B of the second waveguide substrate 201B. The light beam containing image information emitted by the projection device 100 is first modulated by the pre-coupling grating 2021. After diffraction by the pre-coupling grating 2021, the central field of view light beam is deflected toward the positive direction of the X-axis. The light beam modulated by the pre-coupling grating 2021 is then propagated to the coupling grating 2022. After the second diffraction by the coupling grating 2022, all field of view light beams meet the total reflection condition in the waveguide substrate 201 and propagate toward the coupling grating 2023 in the waveguide substrate 201 in a total reflection manner. When the light beam is transmitted to the coupling grating 2023, a two-dimensional exit pupil expansion is achieved, and the light beam transmitted by total reflection is coupled out into the air to be captured by the human eye 300.

[0093] Fig.10 Shown Fig. 9 The near-eye display optical waveguide 200 of the near-eye display device 10 shown is a schematic structural diagram of another embodiment having two layers of waveguide substrates 201 . Fig.10 The embodiment shown is Fig. 9 The embodiment shown is similar, the main difference is that the coupling grating 2022 and the coupling-out grating 2023 are arranged on the fourth surface 2012B of the second waveguide substrate 201B. The light beam containing the image information emitted by the projection device 100 is first modulated by the pre-coupling grating 2021, and after the diffraction of the pre-coupling grating 2021, the central field of view light beam is deflected in the positive direction of the X-axis. The light beam modulated by the pre-coupling grating 2021 is then propagated to the coupling grating 2022, and after the second diffraction of the coupling grating 2022, all the field of view light beams meet the total reflection condition in the waveguide substrate 201, and propagate in the waveguide substrate 201 in the direction of the coupling-out grating 2023 in a total reflection manner. When the light beam is transmitted to the coupling-out grating 2023, a two-dimensional exit pupil expansion is achieved, and the light beam transmitted by total reflection is coupled out into the air to be captured by the human eye 300.

[0094] Fig.11 Shown Fig. 9 The near-eye display optical waveguide 200 of the near-eye display device 10 shown is a schematic structural diagram of another embodiment having a two-layer waveguide substrate 201 . Fig.11The embodiment shown is Fig. 9 The embodiment shown is similar, the main difference is that the pre-coupling grating 2021 is arranged on the second surface 2012A of the first waveguide substrate 201A. The pre-coupling grating 2021 and the coupling grating 2022 are spaced apart in the stacking direction of the two layers of the waveguide substrate 201, and are not in contact. This can be specifically adjusted by setting the assembly size of the microbead glue 204. The light beam containing the image information emitted by the projection device 100 is first modulated by the pre-coupling grating 2021, and after the diffraction of the pre-coupling grating 2021, the central field of view light beam is deflected in the positive direction of the X-axis. The light beam modulated by the pre-coupling grating 2021 is then propagated to the coupling grating 2022, and after the second diffraction of the coupling grating 2022, all the field of view light beams meet the total reflection condition in the waveguide substrate 201, and propagate in the waveguide substrate 201 in the direction of the coupling grating 2023 in a total reflection manner. When the light beam is transmitted to the outcoupling grating 2023 , a two-dimensional exit pupil expansion is achieved, and the light beam transmitted by total reflection is coupled out into the air to be captured by the human eye 300 .

[0095] exist Fig.11 In the illustrated embodiment, the near-eye display optical waveguide 200 is provided with a double-layer waveguide substrate 201, and is bonded and fixed by microbead glue 204, so that the pre-coupled grating 2021, the coupled grating 2022 and the coupled-out grating 2023 are sealed in the gap between the two layers of the waveguide substrate 201. During use, any one of the pre-coupled grating 2021, the coupled-in grating 2022 and the coupled-out grating 2023 cannot be directly contacted. Therefore, the near-eye display device made of the near-eye display optical waveguide 200 of this embodiment does not need to be provided with a protective glass or a protective resin lens on the periphery of the near-eye display optical waveguide 200, and thus has the characteristics of being light and thin.

[0096] Since the wave vectors of incident light of different wavelengths of the same grating 202 are different, the field of view of the near-eye display optical waveguide 200 provided with a set of diffraction gratings, the coupling-in grating 2022-coupling-out grating 2023, is limited. In order to improve the field of view, it is necessary to provide a coupling-in grating 2022 and a coupling-out grating 2023 that are larger than a set of diffraction gratings. The coupling-in grating 2022 and the coupling-out grating 2023 that are larger than a set of diffraction gratings can be provided on different waveguide substrates 201, and integrated by gluing with microbead glue 204 to achieve the function of wavelength splicing or field of view splicing, thereby achieving a larger field of view and a wider display color gamut. In this embodiment, multiple coupling-in gratings 2022 and multiple coupling-out gratings 2023 of multiple sets of diffraction gratings can be further introduced in addition to the pre-coupling grating 2021, thereby achieving the expansion of the field of view and the display wavelength range.

[0097] Fig.12It is a schematic structural diagram of an embodiment in which the near-eye display optical waveguide 200 of the near-eye display device 10 of the present application has a three-layer waveguide substrate 201 . Fig.12 The embodiment shown, with Fig. 9 The embodiment shown is similar, the main difference is that the near-eye display optical waveguide 200 includes a three-layer waveguide substrate 201. The three-layer waveguide substrate 201 includes a first waveguide substrate 201A, a second waveguide substrate 201B and a third waveguide substrate 201C. The first waveguide substrate 201A is located above the second waveguide substrate 201B, and the second waveguide substrate 201B is located above the third waveguide substrate 201C. Among them, the first waveguide substrate 201A includes a first surface 2011A and a second surface 2012A that are oppositely arranged. The first surface 2011A can be the upper surface of the first waveguide substrate 201A, and the second surface 2012A can be the lower bottom surface of the first waveguide substrate 201A. The second waveguide substrate 201B includes a third surface 2011B and a fourth surface 2012B that are oppositely arranged. The third surface 2011B can be the upper surface of the second waveguide substrate 201B, and the fourth surface 2012B can be the lower surface of the second waveguide substrate 201B. The third waveguide substrate 201C includes a fifth surface 2011C and a sixth surface 2012C that are arranged opposite to each other, the fifth surface 2011C may be the upper surface of the third waveguide substrate 201C, and the sixth surface 2012C may be the lower surface of the third waveguide substrate 201C. The grating 202 includes two groups of diffraction gratings, each group of diffraction gratings includes an in-coupling grating 2022 and an out-coupling grating 2023. The two groups of diffraction gratings include two in-coupling gratings 2022 and two out-coupling gratings 2023. The two groups of in-coupling gratings 2022 and out-coupling gratings 2023 include a first in-coupling grating 2022A and a first out-coupling grating 2023A, and a second in-coupling grating 2022B and a second out-coupling grating 2023B.

[0098] exist Fig.12In the illustrated embodiment, the first waveguide substrate 201A and the second waveguide substrate 201B are fixed together by micro-bead glue 204 disposed between the second surface 2012A and the third surface 2011B. The second waveguide substrate 201B and the third waveguide substrate 201C are fixed together by micro-bead glue 204 disposed between the fourth surface 2012B and the fifth surface 2011C. In the near-eye display optical waveguide 200, the pre-coupled grating 2021 and the coupling grating 2022 and the coupling grating 2023 of the two groups of diffraction gratings are disposed on different waveguide substrates 201. The coupling grating 2022 and the coupling grating 2023 disposed on the same layer of the waveguide substrate 201 are disposed on the same surface of the same waveguide substrate 201. Specifically, the pre-coupling grating 2021 is arranged on the second surface 2012A of the first waveguide substrate 201A, and the first coupling grating 2022A and the first coupling grating 2023A of the first group of diffraction gratings are arranged on the third surface 2011B of the second waveguide substrate 201B. The second coupling grating 2022B and the second coupling grating 2023B of the second group of diffraction gratings are arranged on the fifth surface 2011C of the third waveguide substrate 201C. The light beam containing image information emitted by the projection device 100 is first modulated by the pre-coupling grating 2021, and after diffraction by the pre-coupling grating 2021, the central field of view light beam is deflected toward the positive direction of the X-axis. The light beam modulated by the pre-coupling grating 2021 is then propagated to the first coupling grating 2022A. The first coupling-in grating 2022A mainly couples all the blue light of the field of view and part of the green light of the field of view into the second waveguide substrate 201B. After the second diffraction of the first coupling-in grating 2022A, all the blue light of the field of view and part of the green light of the field of view meet the total reflection condition in the second waveguide substrate 201B, and propagate in the second waveguide substrate 201B in the direction of the first coupling-out grating 2023A in a total reflection manner. When all the blue light of the field of view and part of the green light of the field of view are transmitted to the first coupling-out grating 2023A, two-dimensional exit pupil expansion is achieved, and the light beam transmitted by total reflection in the second waveguide substrate 201B is coupled out into the air and captured by the human eye 300. At the same time, all the red light of the field of view and part of the green light of the field of view modulated by the pre-coupling grating 2021 continue to propagate to the second coupling-in grating 2022B after penetrating the first coupling-in grating 2022A. The second coupling-in grating 2022B mainly couples all the red light in the field of view and part of the green light in the field of view into the third waveguide substrate 201C. After the second diffraction of the second coupling-in grating 2022B, all the red light in the field of view and part of the green light in the field of view meet the total reflection condition in the third waveguide substrate 201C, and propagate in the third waveguide substrate 201C in a total reflection manner toward the second coupling-out grating 2023B. When all the red light in the field of view and part of the green light in the field of view are transmitted to the second coupling-out grating 2023B, two-dimensional exit pupil expansion is achieved, and the light beam transmitted by total reflection in the third waveguide substrate 201C is coupled out into the air and captured by the human eye 300.At this time, the human eye can observe the light beams of all three colors of red, green and blue in the field of view at the same time, realizing the full-color display function with a large field of view.

[0099] exist Fig.12 In the embodiment shown, the coupling-in grating 2022 and the coupling-out grating 2023 of the same group of diffraction gratings can be arranged on any surface of the same layer of waveguide substrate 201 according to actual needs, and the coupling-in grating 2022 and the coupling-out grating 2023 of the same group of diffraction gratings can be on the same side or on different sides, but the coupling-in grating 2022 and the coupling-out grating 2023 of the same group of diffraction gratings must be arranged on the same layer of waveguide substrate 201. Fig.12 In the illustrated embodiment, the near-eye display optical waveguide 200 is provided with a three-layer waveguide substrate 201, and is bonded and fixed by microbead glue 204, so that the pre-coupled grating 2021, the first coupled grating 2022A, the first coupled out grating 2023A, the second coupled grating 2022B, and the second coupled out grating 2023B are sealed in the gap between the three-layer waveguide substrate 201 stacked layers, and any one of the pre-coupled grating 2021, the first coupled grating 2022A, the first coupled out grating 2023A, the second coupled grating 2022B, and the second coupled out grating 2023B cannot be directly contacted during use. Therefore, the near-eye display device made of the near-eye display optical waveguide 200 of this embodiment does not need to be provided with a protective glass or a protective resin lens on the periphery of the near-eye display optical waveguide 200, and thus has the characteristics of being light and thin.

[0100] Fig.13 Shown Fig.12 The wave vector analysis diagram of an embodiment of the second waveguide substrate 201B of the near-eye display optical waveguide 200 of the near-eye display device 10 is shown. Fig.13 In the illustrated embodiment, the pre-coupling grating 2021, the first coupling grating 2022A and the first coupling grating 2023A form a second wave vector circle 205 in the second waveguide substrate 201B. The second wave vector circle 205 represents the propagation of all the field of view blue light and part of the field of view green light in the second waveguide substrate 201B in the second waveguide substrate 201B. The second wave vector circle 205 includes a second wave vector inner circle 2051 and a second wave vector outer circle 2052. The radius of the second wave vector inner circle 2051 is 1.00, indicating that the second waveguide substrate 201B is in an air environment with a refractive index of about 1.00. The radius of the second wave vector outer circle 2052 is 1.90, indicating that the refractive index of the second waveguide substrate 201B is 1.90. The second wave vector circle 205 includes an incident light field / an outgoing light field 2053, a blue light pre-coupling modulation field 2054, a green light pre-coupling modulation field 2055, a blue light coupling modulation field 2056, a green light coupling modulation field 2057, a blue light out-coupling turning field 2058 and a green light out-coupling turning field 2059.

[0101] exist Fig.13 In the illustrated embodiment, the incident light field of view 2053 is represented by a solid rectangular frame at the center of the wave vector circle of the second wave vector circle 205, the dashed rectangular frame represents the field of view distribution of green light, and the dashed rectangular frame represents the field of view distribution of blue light. After the modulation of the pre-coupling grating 2021, the incident light field of view 2053 moves along the positive direction of the X-axis, and the moving distance is the wave vector k_pre of the pre-coupling grating 2021. It should be noted that the blue light pre-coupling modulation field of view 2054 and the green light pre-coupling modulation field of view 2055 after modulation by the pre-coupling grating 2021 must be located within the second wave vector circle 205. Afterwards, all the field of view blue light and part of the field of view green light after modulation by the pre-coupling grating 2021 continue to be incident on the first coupling grating 2022A. After the second modulation of the first coupling grating 2022A, the blue light field area continues to move along the positive direction of the X axis to the blue light coupling modulation field of view 2056, and the green light field area continues to move along the positive direction of the X axis to the green light coupling modulation field of view 2057. The moving distance is the wave vector k_in_1 of the first coupling grating 2022A. At this time, the light beams of the entire field of view blue light and part of the field of view green light meet the total reflection condition and can be transmitted losslessly in the second waveguide substrate 201B.

[0102] When the light beam is transmitted to the first outcoupling grating 2023A, a two-dimensional exit pupil expansion is achieved, and the light beam transmitted by total reflection in the second waveguide substrate 201B is coupled out to the air to be captured by the human eye 300. Since the first outcoupling grating 2023A is a two-dimensional grating, the entire field of view blue light and part of the field of view green light in the second waveguide substrate 201B can be coupled out of the second waveguide substrate 201B via two main wave vector paths and enter the human eye 300. The first outcoupling path is to directly couple out via the wave vector k_out_11 to reach the output light field of view 2053, and the second outcoupling path is to first reach the blue light outcoupling turning field of view 2058 and the green light outcoupling turning field of view 2059 (related to the wavelength) via the wave vector k_out_121, and then reach the output light field of view 2058 via the wave vector k_out_122. It should be noted that the blue light out-coupling turning field 2058 after the second modulation by the first coupling grating 2022A and the turning by the first coupling grating 2023A is entirely located within the second wave vector outer circle 2052 of the second wave vector circle 205 and outside the second wave vector inner circle 2051, and the green light out-coupling turning field 2059 after the second modulation by the first coupling grating 2022A and the turning by the first coupling grating 2023A is partially located within the second wave vector outer circle 2052 of the second wave vector circle 205 and outside the second wave vector inner circle 2051. In the second waveguide substrate 201B, no matter the light beam transmitted in the outcoupling region is coupled out via the first outcoupling path or the second outcoupling path, for the first coupling-in grating 2022A and the first outcoupling grating 2023A, the sum of the grating vectors of the pre-coupling grating 2021 and the first coupling-in grating 2022A is equal in magnitude and opposite in direction to the grating vector of the first outcoupling grating 2023A, that is,

[0103]

[0104] At this time, the sum of the overall grating wave vectors of the pre-coupling grating 2021 , the first coupling grating 2022A, and the first coupling out grating 2023A is 0, which meets the wave vector requirement of the near-eye display optical waveguide 200 .

[0105] Fig.14 Shown Fig.12 The wave vector analysis diagram of an embodiment of the third waveguide substrate 201C of the near-eye display optical waveguide 200 of the near-eye display device 10 is shown. Fig.14In the illustrated embodiment, the pre-coupling grating 2021, the second coupling grating 2022B and the second coupling-out grating 2023B form a third wave vector circle 206 in the third waveguide substrate 201C. The third wave vector circle 206 represents the propagation of all the field of view red light and part of the field of view green light in the third waveguide substrate 201C in the third waveguide substrate 201C. The third wave vector circle 206 includes a third wave vector inner circle 2061 and a third wave vector outer circle 2062. The radius of the third wave vector inner circle 2061 is 1.00, indicating that the third waveguide substrate 201C is in an air environment with a refractive index of about 1.00. The radius of the third wave vector outer circle 2062 is 1.90, indicating that the refractive index of the third waveguide substrate 201C is 1.90. The third wave vector circle 206 includes an incident light field / an outgoing light field 2063, a green light pre-coupling modulation field 2064, a red light pre-coupling modulation field 2065, a green light coupling modulation field 2066, a red light coupling modulation field 2067, a green light out-coupling turning field 2068 and a red light out-coupling turning field 2069.

[0106] exist Fig.14 In the illustrated embodiment, the incident light field of view 2063 is represented by a solid rectangular frame at the center of the third wave vector circle 206, the dashed rectangular frame represents the field of view distribution of green light, and the double-dash rectangular frame represents the field of view distribution of red light. After the modulation of the pre-coupling grating 2021, the incident light field of view 2063 moves along the positive direction of the X-axis, and the moving distance is the wave vector k_pre of the pre-coupling grating 2021. It should be noted that the green light pre-coupling modulation field of view 2064 and the red light pre-coupling modulation field of view 2065 after modulation by the pre-coupling grating 2021 must be located inside the third wave vector circle 206. Afterwards, all the field of view red light and part of the field of view green light after modulation by the pre-coupling grating 2021 continue to be incident on the second coupling grating 2022B. After the second modulation by the second coupling grating 2022B, the red light field of view area continues to move along the positive direction of the X axis to the red light coupling modulation field of view 2067, and the green light field of view area continues to move along the positive direction of the X axis to the green light coupling modulation field of view 2066. The moving distance is the wave vector k_in_12 of the second coupling grating 2022B. At this time, the light beams of the entire field of view red light and part of the field of view green light meet the total reflection condition and can be transmitted losslessly in the third waveguide substrate 201C.

[0107] When the light beam is transmitted to the second outcoupling grating 2023B, a two-dimensional exit pupil expansion is achieved, and the light beam transmitted by total reflection in the third waveguide substrate 201C is coupled out to the air to be captured by the human eye 300. Since the second outcoupling grating 2023B is a two-dimensional grating, all the red light of the field of view and part of the green light of the field of view in the third waveguide substrate 201C can be coupled out of the third waveguide substrate 201C via two main wave vector paths and enter the human eye 300. The first outcoupling path is to directly couple out via the wave vector k_out_21 to reach the output light field of view 2063, and the second outcoupling path is to first reach the green light outcoupling turning field of view 2068 or the red light outcoupling turning field of view 2069 (related to the wavelength) via the wave vector k_out_221, and then reach the red light outcoupling turning field of view 2069 via the wave vector k_out_222. It should be noted that the light out-coupling turning field 2069 after the second modulation by the second coupling-in grating 2022B and the turning by the second coupling-out grating 2023B is entirely located within the third wave vector outer circle 2062 of the third wave vector circle 206 and outside the third wave vector inner circle 2061, and the green light out-coupling turning field 2068 after the second modulation by the second coupling-in grating 2022B and the turning by the second coupling-out grating 2023B is partially located within the third wave vector outer circle 2062 and outside the third wave vector inner circle 2061. In the third waveguide substrate 201C, no matter the light beam transmitted in the out-coupling region is coupled out via the first coupling-out path or the second coupling-out path, for the second coupling-in grating 2022B and the second coupling-out grating 2023B, the sum of the grating vectors of the pre-coupling grating 2021 and the second coupling-in grating 2022B is equal in magnitude and opposite in direction to the grating vector of the second coupling-out grating 2023B, that is,

[0108]

[0109] At this time, the sum of the overall grating wave vectors of the pre-coupled grating 2021, the second coupled grating 2022B, and the second coupled out grating 2023B is 0, which meets the wave vector requirements of the near-eye display optical waveguide 200.

[0110] exist Fig.13 and Fig.14 In the illustrated embodiment, the near-eye display optical waveguide 200 has two coupling-in gratings 2022 and two coupling-out gratings 2023 of two groups of diffraction gratings. The introduction of the pre-coupling grating 2021 can make the near-eye display optical waveguide 200 have the advantages of a larger viewing angle and a wider incident light wavelength range, and can greatly improve the coupling efficiency of the near-eye display optical waveguide 200. In addition, the two coupling-in gratings 2022 and two coupling-out gratings 2023 of the two groups of diffraction gratings can share the same pre-coupling grating 2021, and the pre-coupling grating 2021 can be directly prepared on the first waveguide substrate 201A as a grating protection glass, without the need for additional waveguide costs, and has extremely high cost-effectiveness while significantly improving performance.

[0111] In order to further expand the field of view of the near-eye display optical waveguide 200, the near-eye display optical waveguide 200 includes a four-layer waveguide substrate, and three coupling-in gratings 2022 and three coupling-out gratings 2023 of three groups of diffraction gratings disposed on the four-layer waveguide substrate. In this way, the field of view and the display wavelength range can be further expanded.

[0112] Fig.15 It is a schematic structural diagram of an embodiment in which the near-eye display optical waveguide 200 of the near-eye display device 10 of the present application has a four-layer waveguide substrate 201. Fig.15 The embodiment shown, with Fig.12 The embodiment shown is similar, with the main difference being that the near-eye display optical waveguide 200 includes a four-layer waveguide substrate 201. The four-layer waveguide substrate 201 includes a first waveguide substrate 201A, a second waveguide substrate 201B, a third waveguide substrate 201C, and a fourth waveguide substrate 201D. The first waveguide substrate 201A is located above the second waveguide substrate 201B, and the second waveguide substrate 201B is located above the third waveguide substrate 201C. The first waveguide substrate 201A includes a first surface 2011A and a second surface 2012A that are oppositely disposed, the first surface 2011A may be the upper surface of the first waveguide substrate 201A, and the second surface 2012A may be the lower bottom surface of the first waveguide substrate 201A. The second waveguide substrate 201B includes a third surface 2011B and a fourth surface 2012B that are arranged opposite to each other. The third surface 2011B may be the upper surface of the second waveguide substrate 201B, and the fourth surface 2012B may be the lower surface of the second waveguide substrate 201B. The third waveguide substrate 201C includes a fifth surface 2011C and a sixth surface 2012C that are arranged opposite to each other. The fifth surface 2011C may be the upper surface of the third waveguide substrate 201C, and the sixth surface 2012C may be the lower surface of the third waveguide substrate 201C. The fourth waveguide substrate 201D includes a seventh surface 2011D and an eighth surface 2012D that are arranged opposite to each other. The seventh surface 2011D may be the upper surface of the fourth waveguide substrate 201D, and the eighth surface 2012D may be the lower surface of the fourth waveguide substrate 201D. The grating 202 includes three groups of diffraction gratings, each group of diffraction gratings includes an in-coupling grating 2022 and an out-coupling grating 2023. The three groups of diffraction gratings include three coupling-in gratings 2022 and three coupling-out gratings 2023. The three groups of diffraction gratings include a first coupling-in grating 2022A and a first coupling-out grating 2023A, a second coupling-in grating 2022B and a second coupling-out grating 2023B, and a third coupling-in grating 2022C and a third coupling-out grating 2023C.

[0113] exist Fig.15In the illustrated embodiment, the first waveguide substrate 201A and the second waveguide substrate 201B are fixed together by micro-bead glue 204 disposed between the second surface 2012A and the third surface 2011B. The second waveguide substrate 201B and the third waveguide substrate 201C are fixed together by micro-bead glue 204 disposed between the fourth surface 2012B and the fifth surface 2011C. The third waveguide substrate 201C and the fourth waveguide substrate 201D are fixed together by micro-bead glue 204 disposed between the sixth surface 2012C and the seventh surface 2011D. In the near-eye display optical waveguide 200, the pre-coupled grating 2021 and the three coupling gratings 2022 and the three coupling gratings 2023 of the three groups of diffraction gratings are disposed on different waveguide substrates 201. The coupling grating 2022 and the coupling grating 2023 disposed on the same layer of the waveguide substrate 201 are disposed on the same surface of the same waveguide substrate 201. Specifically, the pre-coupling grating 2021 is arranged on the second surface 2012A of the first waveguide substrate 201A, and the first coupling grating 2022A and the first coupling grating 2023A of the first group of diffraction gratings are arranged on the third surface 2011B of the second waveguide substrate 201B. The second coupling grating 2022B and the second coupling grating 2023B of the second group of diffraction gratings are arranged on the fifth surface 2011C of the third waveguide substrate 201C. The third coupling grating 2022C and the third coupling grating 2023C of the third group of diffraction gratings are arranged on the seventh surface 2011D of the fourth waveguide substrate 201D. The light beam containing the image information emitted by the projection device 100 is first modulated by the pre-coupling grating 2021, and after diffraction by the pre-coupling grating 2021, the central field of view light beam is deflected toward the positive direction of the X-axis.

[0114] The light beam modulated by the pre-coupling grating 2021 then propagates to the first coupling grating 2022A. The first coupling grating 2022A mainly couples all the blue light in the field of view and the red and green light in part of the field of view into the second waveguide substrate 201B. After the second diffraction of the first coupling grating 2022A, all the blue light in the field of view and the red and green light in part of the field of view meet the total reflection condition in the second waveguide substrate 201B, and propagate in the second waveguide substrate 201B in a total reflection manner toward the first coupling grating 2023A. Afterwards, the uncoupled light beam penetrates the second waveguide substrate 201B and continues to propagate to the second coupling grating 2022B. The second coupling grating 2022B mainly couples all the green light in the field of view and the red and blue light in part of the field of view into the third waveguide substrate 201C. After the second diffraction of the second coupling grating 2022B, all the green light in the field of view and the red and blue light in part of the field of view meet the total reflection condition in the third waveguide substrate 201C, and propagate in the third waveguide substrate 201C in a total reflection manner toward the second coupling grating 2023B. Afterwards, the light beam that has not been coupled in penetrates the third waveguide substrate 201C and continues to propagate to the third coupling-in grating 2022C. The third coupling-in grating 2022C mainly couples all the red light in the field of view and the blue-green light in part of the field of view into the fourth waveguide substrate 201D. After the second diffraction of the third coupling-in grating 2022C, all the red light in the field of view and the blue-green light in part of the field of view meet the total reflection condition in the fourth waveguide substrate 201D, and propagate in the fourth waveguide substrate 201D in a total reflection manner toward the third coupling-out grating 2023C. At this time, the human eye 300 can observe the light beams in all the fields of view of red, green and blue at the same time, and can achieve ultra-large field of view full-color wide color gamut display performance.

[0115] exist Fig.15 In the embodiment shown, the coupling-in grating 2022 and the coupling-out grating 2023 of the same group of diffraction gratings can be arranged on any surface of the same layer of waveguide substrate 201 according to actual needs, and the coupling-in grating 2022 and the coupling-out grating 2023 of the same group of diffraction gratings can be on the same side or on different sides, but the coupling-in grating 2022 and the coupling-out grating 2023 of the same group of diffraction gratings must be arranged on the same layer of waveguide substrate 201. Fig.15In the embodiment shown, the near-eye display optical waveguide 200 is provided with four layers of waveguide substrate 201, and is bonded and fixed by micro-bead glue 204, so that the pre-coupled grating 2021, the first coupled grating 2022A, the first coupled grating 2023A, the second coupled grating 2022B, the second coupled grating 2023B, the third coupled grating 2022C and the third coupled grating 2023D are sealed in the gaps of the stacked layers of the four layers of waveguide substrate 201, and cannot be directly It contacts any one of the pre-coupling grating 2021, the first coupling grating 2022A, the first coupling grating 2023A, the second coupling grating 2022B, the second coupling grating 2023B, the third coupling grating 2022C and the third coupling grating 2023D. Therefore, the near-eye display device made of the near-eye display optical waveguide 200 of this embodiment does not need to set a protective glass or a protective resin lens on the periphery of the near-eye display optical waveguide 200, so it has the characteristics of being light and thin.

[0116] In some other embodiments, the diffraction grating further includes a turning grating (not shown), the coupling-in grating 2022, the turning grating and the coupling-out grating 2023 are located on the same layer of the waveguide substrate 201, and in the direction of the center line of the coupling-in grating 2022 and the coupling-out grating 2023, the turning grating is located between the coupling-in grating 2022 and the coupling-out grating 2023. Such an arrangement improves the coupling efficiency. In some embodiments, the near-eye display optical waveguide 200 includes a single-layer waveguide substrate 201. The grating 202 includes a group of diffraction gratings, and the group of diffraction gratings includes a coupling-in grating 2022, a turning grating and a coupling-out grating 2023. The turning grating provides a variety of grating vectors. The sum of the grating vectors provided by the pre-coupling grating 2021 and the coupling-in grating 2022 is equal in size and opposite in direction to a grating vector or a combination of multiple grating vectors provided by the turning grating and the coupling-out grating 2023. Such an arrangement improves the energy utilization rate. In some embodiments, the near-eye display optical waveguide 200 includes a multilayer waveguide substrate 201. The near-eye display optical waveguide 200 includes two or more layers of waveguide substrates 201. The grating 202 includes multiple groups of diffraction gratings, each group of diffraction gratings includes a coupling-in grating 2022, a turning grating and a coupling-out grating 2023. The multiple groups of diffraction gratings include multiple coupling-in gratings 2022, multiple turning gratings and multiple coupling-out gratings 2023. The turning grating provides multiple grating vectors. The coupling-in grating 2022, the coupling-out grating 2023 and the turning grating located on the same layer of waveguide substrate 201 all satisfy that the sum of the grating vectors provided by the pre-coupling grating 2021 and the coupling-in grating 2022 is equal to the sum of the grating vectors provided by the turning grating and the coupling-out grating 2023 or the combination of multiple grating vectors is equal in size and opposite in direction. This arrangement improves energy utilization.

[0117] Fig.16The figure shows a comparison of the energy distribution of the near-eye display device 10 in the present application and the related art within the two-dimensional field of view distribution range. Fig.16 As shown, the left figure is a two-dimensional field of view energy distribution 2071 of the near-eye display device 10 prepared using the near-eye display optical waveguide 200 provided in this embodiment, and the right figure is a two-dimensional field of view energy distribution 2072 of the near-eye display device prepared based on the SRG technology in the related art. For the convenience of comparison, the vertical axes of the two figures are normalized and consistent. From the comparison, it can be seen that the energy coupling value of the near-eye display device 10 prepared using the near-eye display optical waveguide 200 provided in this embodiment within the entire two-dimensional field of view is approximately two to three times the energy coupling value of the near-eye display device prepared based on the SRG technology in the related art. This means that for the same projection device 100, the near-eye display optical waveguide 200 provided in this embodiment has an energy utilization rate of about two to three times that of the AR optical waveguide in the related art, which means a significant improvement in display brightness.

[0118] The present embodiment provides a solution of a near-eye display optical waveguide 200 having a pre-coupling grating 2021 and at least one group of diffraction gratings (coupling grating 2022 and out-coupling grating 2023). By establishing a grating vector limitation between the wave vectors of a pre-coupling grating 2021 and at least one group of diffraction gratings (coupling grating 2022 and out-coupling grating 2023), a near-eye display optical waveguide 200 with higher energy utilization and lower manufacturing cost is realized, thereby realizing a near-eye display device 10 with better near-eye display performance.

[0119] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A near-eye display optical waveguide, characterized in that: include: At least one waveguide substrate and a grating arranged on the waveguide substrate, the grating includes a pre-coupling grating and at least one group of diffraction gratings, the diffraction grating includes a coupling-in grating and a coupling-out grating; in the transmission direction along the light beam, the coupling-in grating is located behind the pre-coupling grating, and in the direction of the center line connecting the coupling-in grating and the coupling-out grating, the coupling-in grating is arranged close to the coupling-out grating relative to the pre-coupling grating; wherein the pre-coupling grating is used to diffract the light beam to the coupling-in grating, the coupling-in grating is used to couple the light beam diffracted by the pre-coupling grating into the waveguide substrate, and transmit it along the waveguide substrate to the coupling-out grating, and the coupling-out grating is used to couple the light beam out of the waveguide substrate.

2. The near-eye display optical waveguide according to claim 1, characterized in that: The pre-coupling grating and the coupling-in grating each provide a single grating vector, the coupling-out grating provides at least one grating vector, the sum of the grating vectors provided by the pre-coupling grating and the coupling-in grating is equal in magnitude to a grating vector or a combination of multiple grating vectors provided by the coupling-out grating, and has an opposite direction; wherein the magnitude of the grating vector is equal to 2π multiplied by the inverse of the grating period of the grating, and the direction of the grating vector is perpendicular to the grating period arrangement direction.

3. The near-eye display optical waveguide according to claim 1 or 2, characterized in that: The near-eye display optical waveguide includes a single layer of the waveguide substrate; the grating includes a group of the diffraction gratings, and the group of the diffraction gratings includes a coupling-in grating and a coupling-out grating; the pre-coupling grating and the coupling-in grating are located on different surfaces of the waveguide substrate, and the coupling-out grating is located on any surface of the waveguide substrate.

4. The near-eye display optical waveguide according to claim 1 or 2, characterized in that: The near-eye display optical waveguide includes multiple layers of the waveguide substrate; the grating includes multiple groups of the diffraction gratings, each group of the diffraction gratings includes one coupling-in grating and one coupling-out grating; the pre-coupling grating is arranged on the waveguide substrate located at the top of the multiple layers of the waveguide substrate, and the multiple coupling-in gratings and multiple coupling-out gratings of the multiple groups of the diffraction gratings are arranged on one of the layers of the waveguide substrate located below the top of the multiple layers of the waveguide substrate; wherein, in the direction of transmission along the light beam, the pre-coupling grating is located above the multiple groups of the diffraction gratings and on any surface of the waveguide substrate at the top; the coupling-in grating and the coupling-out grating of each group of the diffraction gratings are located on the same layer of the waveguide substrate and are respectively located on the same surface or different surfaces of the same layer of the waveguide substrate.

5. The near-eye display optical waveguide according to claim 4, characterized in that: In the direction of the center line connecting the coupling-in grating and the coupling-out grating, a plurality of the coupling-in gratings are arranged close to the coupling-out grating relative to the pre-coupling grating; The coupling-in grating which is farther from the pre-coupling grating is arranged closer to the coupling-out grating; and / or The farther the coupling grating is from the pre-coupling grating, the larger the area of ​​the coupling grating is.

6. The near-eye display optical waveguide according to claim 4, characterized in that: The coupling-in grating and the coupling-out grating of a group of the diffraction gratings located on the same layer of the waveguide substrate all satisfy that the sum of the grating vectors provided by the pre-coupling grating and the coupling-in grating is equal in magnitude to a grating vector or a combination of multiple grating vectors provided by the coupling-out grating and has an opposite direction; and / or The thickness of the waveguide substrate at the top is smaller than the thickness of any layer of the waveguide substrate below the top; and / or The thickness of the multiple layers of the waveguide substrate located below the top portion is equal.

7. The near-eye display optical waveguide according to claim 4, characterized in that: The pre-coupling grating and the coupling grating are located between the two waveguide substrates in a stacked arrangement, and are spaced apart and not in contact with each other in the stacking direction.

8. The near-eye display optical waveguide according to claim 7, characterized in that: The two stacked waveguide substrates are connected by micro-bead glue, and the assembly size range of the micro-bead glue is 5 μm to 500 μm.

9. The near-eye display optical waveguide according to claim 1 or 2, characterized in that: The diffraction grating also includes a turning grating. The coupling-in grating, the turning grating and the coupling-out grating are located on the same layer of the waveguide substrate, and in the direction of the center line connecting the coupling-in grating and the coupling-out grating, the turning grating is located between the coupling-in grating and the coupling-out grating.

10. The near-eye display optical waveguide according to claim 9, characterized in that: The near-eye display optical waveguide comprises a single-layer waveguide substrate; the grating comprises a group of diffraction gratings, and the group of diffraction gratings comprises one coupling-in grating, one turning grating and one coupling-out grating; the turning grating provides a plurality of grating vectors; the sum of the grating vectors provided by the pre-coupling grating and the coupling-in grating is equal in magnitude to a grating vector or a combination of multiple grating vectors provided by the turning grating and the coupling-out grating, and has an opposite direction; or The near-eye display optical waveguide includes multiple layers of the waveguide substrate; the grating includes multiple groups of the diffraction gratings, each group of the diffraction gratings includes one coupling-in grating, one turning grating and one coupling-out grating; the turning grating provides multiple grating vectors; the coupling-in grating, the coupling-out grating and the turning grating located in the same layer of the waveguide substrate all satisfy that the sum of the grating vectors provided by the pre-coupling grating and the coupling-in grating is equal in size to a grating vector or a combination of multiple grating vectors provided by the turning grating and the coupling-out grating, and the directions are opposite.

11. The near-eye display optical waveguide according to claim 1, characterized in that: The pre-coupling grating, the coupling grating and the out-coupling grating are all sub-wavelength optical structures; The sub-wavelength optical structure is a regular area surrounded by straight edges, or surrounded by arc edges, or surrounded by straight edges and arc edges; and / or The surface of the sub-wavelength optical structure is provided with an optical coating or a coating; the material of the optical coating or the coating is one or a combination of at least two of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium oxide, and zirconium oxide; and / or The material of the sub-wavelength optical structure comprises at least one or more combinations of optical glass, optical resin and optical glass material; and / or The refractive index of the sub-wavelength optical structure is the same as or different from the refractive index of the waveguide substrate.

12. The near-eye display optical waveguide according to claim 1, characterized in that: The pre-coupling grating comprises at least one of a one-dimensional straight tooth grating, a two-dimensional straight tooth grating, a blazed grating or a tilted grating; and / or The coupling-in grating comprises at least one of a one-dimensional straight tooth grating, a two-dimensional straight tooth grating, a blazed grating or a tilted grating; and / or The pre-coupled grating comprises at least one of a photonic crystal, a metamaterial or a surface; and / or The coupling-in grating comprises at least one of a photonic crystal, a metamaterial or a surface; and / or The outcoupling grating comprises at least one of a photonic crystal, a metamaterial or a surface; and / or The outcoupling grating comprises a columnar structure, a cone structure or a terrace structure; and / or The near-eye display optical waveguide includes multiple layers of the waveguide substrate, and the refractive indexes of any two layers of the waveguide substrate are the same or different.

13. The near-eye display optical waveguide according to claim 1, characterized in that: The surface of the waveguide substrate is a plane or a curved surface, wherein the curved surface is a convex surface, a concave surface, an aspherical surface, or a free-form surface; and / or The surface of the waveguide substrate is provided with an optical coating; the material of the optical coating or the coating is one of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium oxide, and zirconium oxide, or a combination of at least two thereof.

14. A near-eye display device, characterized in that: include: Projection device; and The near-eye display light waveguide according to any one of claims 1 to 13, wherein the projection device is disposed on one side of the near-eye display light waveguide; the projection device is used to emit a light beam containing image information to the pre-coupled grating of the near-eye display light waveguide.

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