Single light machine binocular near-eye display system and AR glasses

Abstract

The application relates to the technical field of optical display, in particular to a single-optical-machine binocular near-eye display system and AR glasses, which comprise an optical-machine module, a light-splitting module, waveguide lenses and an angle compensation module. The light-splitting module is arranged in the light-out direction of the optical-machine module and is used for splitting an image light beam into a first light beam and a second light beam, the propagation direction of the first light beam is defined as a first light path, and the propagation direction of the second light beam is defined as a second light path; a group of waveguide lenses is arranged in the first light path, and another group of waveguide lenses is arranged in the second light path; an adjustable included angle is formed between the waveguide lenses and the light-splitting module; the angle compensation module is arranged between the waveguide lenses and the light-splitting module, and the angle compensation module is used for compensating for the light incidence angle deviation caused by the change of the adjustable included angle when the adjustable included angle changes, so that the incidence angle of the light when the light is coupled into the waveguide lenses is kept within a design angle range. The application has the effect of keeping the imaging brightness and quality stable after angle adjustment.

Description

Technical Field

[0001] This application relates to the field of optical display technology, and in particular to a single-optical-engine binocular near-eye display system and AR glasses. Background Technology

[0002] Currently, augmented reality (AR) technology aims to overlay computer-generated virtual information onto the real world observed by users, thereby providing an enhanced interactive experience. AR glasses, as the primary carrier of this technology, have an optical display system as one of their core components. This system typically consists of a miniature projection engine for generating images and a waveguide lens for transmitting the image beam to the user's eyes. To provide users with an immersive stereoscopic visual experience, binocular display systems—systems that can simultaneously provide images to both eyes—are the mainstream direction for AR glasses development.

[0003] In related technologies, one technical approach to achieving binocular display in AR glasses is the "one-to-two" single-optical-engine solution. This solution uses a single optical engine and splits the image beam output from the optical engine into two beams via a beam splitter (such as a beam splitter prism or beam splitter waveguide), which are then directed into the left and right waveguide lenses respectively. Furthermore, to improve wearing comfort and adapt to different user face shapes or to meet the design requirements of different styles of glasses (such as sports or business styles), some solutions also incorporate an adjustable angle design, meaning the angle between the left and right waveguide lenses relative to the central component on the bridge of the nose can be adjusted.

[0004] Regarding the aforementioned technologies: when the angle between the waveguide lens and the beam splitter changes, the incident angle of the light rays coupled from the beam splitter entering the diffraction grating in the coupling region of the waveguide lens will deviate from the Bragg angle of the grating, resulting in a significant decrease in the diffraction efficiency of the coupling grating. This can easily cause uneven brightness between the left and right eyes and deterioration of image quality, and consequently, the inability to maintain stable image brightness and quality after angle adjustment. Summary of the Invention

[0005] In order to maintain stable imaging brightness and quality after angle adjustment, this application provides a single-optical-engine binocular near-eye display system and AR glasses.

[0006] In the first aspect, this application provides a single-optical binocular near-eye display system, which adopts the following technical solution:

[0007] A single-optical binocular near-eye display system includes:

[0008] Optomechanical module, used to output image beams;

[0009] A beam splitting module is disposed in the light output direction of the optomechanical module to split the image beam into a first beam and a second beam, wherein the propagation direction of the first beam is defined as the first optical path and the propagation direction of the second beam is defined as the second optical path.

[0010] Two sets of waveguide lenses are provided. One set of waveguide lenses is provided in the first optical path, and the other set of waveguide lenses is provided in the second optical path. An adjustable angle is formed between the waveguide lenses and the beam splitting module.

[0011] The angle compensation module is provided in two sets. One set of the angle compensation module is disposed between one of the waveguide mirrors and the beam splitting module and located in the first optical path. The other set of the angle compensation module is disposed between another waveguide mirror and the beam splitting module and located in the second optical path. The angle compensation module is used to compensate for the light incident angle shift caused by the change of the adjustable angle when the adjustable angle changes, so that the incident angle shift when the light couples into the waveguide mirror is reduced.

[0012] By adopting the above technical solution, the angle compensation module can compensate for this offset, thereby reducing the incident angle offset when light enters the waveguide lens. This ensures the diffraction efficiency of the waveguide lens coupling area under different adjustable angle settings, thus ensuring uniform brightness and stable imaging quality for both eyes. This solves the problem of decreased diffraction efficiency in the waveguide lens coupling area caused by angle changes in the prior art, and realizes stable operation of the single-optical-mechanical binocular display system under angle changes.

[0013] Optionally, the angle compensation module includes an elastic coupling block disposed between the waveguide lens and the beam splitting module. The elastic coupling block has a first optical surface and a second optical surface disposed opposite to each other. The first optical surface is connected to the beam splitting module, and the second optical surface is connected to the waveguide lens.

[0014] When the adjustable angle is zero, the first optical surface and the second optical surface are parallel, and the elastic coupling block is in the form of a parallel plate. When the adjustable angle is greater than zero, the second optical surface tilts with the waveguide lens, and the elastic coupling block undergoes shear deformation to form a wedge shape, which deflects the light passing through the elastic coupling block to compensate for the incident angle shift.

[0015] By adopting the above technical solution, when the adjustable angle is zero, the first and second optical surfaces of the elastic coupling block are parallel, forming a parallel plate shape. Light passes perpendicularly through the elastic coupling block without deflection, and is incident on the waveguide lens at the optimal angle, resulting in the highest diffraction efficiency. When the adjustable angle is greater than zero, the tilt of the waveguide lens causes the second optical surface of the elastic coupling block to tilt as well. The elastic coupling block undergoes shear deformation due to the angle difference between the two optical surfaces, forming a wedge shape. According to the refraction and deflection formula of a thin wedge prism, the deformed elastic coupling block forms a wedge prism with a wedge angle approximately equal to the change in the adjustable angle. Light passes through the wedge-shaped elastic coupling block and is deflected, thus facilitating approximate compensation for the incident angle shift. This reduces the incident angle shift when the light reaches the waveguide lens, thereby helping to reduce fluctuations in diffraction efficiency and improve imaging quality.

[0016] Optionally, the elastic coupling block is made of optical-grade polydimethylsiloxane or optical-grade thermoplastic polyurethane elastomer, and the side of the elastic coupling block is coated with a light-absorbing coating.

[0017] By adopting the above technical solution, optical-grade polydimethylsiloxane or optical-grade thermoplastic polyurethane elastomers possess excellent optical properties and elasticity, meeting the requirements of the elastic coupling block for optical transparency and elastic deformation capability. When the adjustable angle changes, the elastic coupling block can undergo shear deformation to form a wedge shape, deflecting the light to compensate for the incident angle shift. Furthermore, the light-absorbing coating on the side of the elastic coupling block can absorb stray light that may leak from the side, preventing stray light from interfering with the system's imaging and thus improving the imaging quality of the single-optical binocular near-eye display system.

[0018] Optionally, the refractive index of the elastic coupling block is greater than the refractive index of air and less than the refractive index of the beam splitter module and the waveguide lens.

[0019] By adopting the above technical solution, the refractive index of the elastic coupling block is greater than that of air, which enables the elastic coupling block to generate a larger refractive deflection angle when it undergoes wedge deformation. At the same time, it reduces the interface refractive index difference between the elastic coupling block and the beam splitter module and waveguide lens, thereby reducing interface reflection loss. The refractive index of the elastic coupling block is less than that of the waveguide lens, which ensures that the light still meets the total internal reflection condition inside the waveguide lens.

[0020] Optionally, the angle compensation module includes a liquid crystal coupling layer and a control component. The liquid crystal coupling layer is embedded in the elastic coupling block, and the control component is disposed on the side wall of the beam splitting module and electrically connected to the liquid crystal coupling layer. The control component is used to control the equivalent refractive index of the liquid crystal coupling layer so that light passes through the liquid crystal coupling layer and undergoes refraction deflection to compensate for the incident angle shift.

[0021] By adopting the above technical solution, the liquid crystal coupling layer works in conjunction with the control component. The control component controls the equivalent refractive index of the liquid crystal coupling layer, so that light is refracted and deflected when passing through the liquid crystal coupling layer. When the adjustable angle changes, it accurately compensates for the offset of the incident angle of the light caused by the angle change, ensuring that the incident angle of the light when it couples into the waveguide lens is kept within the design angle range. This ensures uniform brightness and stable imaging quality for the left and right eyes under different angle settings, and also results in low additional power consumption.

[0022] Optionally, the liquid crystal coupling layer includes a first substrate, a first transparent electrode, a first alignment layer, a liquid crystal layer, a second alignment layer, a second transparent electrode, and a second substrate, which are sequentially stacked within the elastic coupling block. The first substrate is disposed close to the first optical surface, and the second substrate is disposed close to the second optical surface. The control component is electrically connected to the first transparent electrode and the second transparent electrode, respectively, and the control component is used to adjust the equivalent refractive index of the liquid crystal layer.

[0023] By employing the above technical solution, the control component is electrically connected to the first and second transparent electrodes, respectively, and can apply a driving voltage to the liquid crystal layer. Due to the birefringence and electro-optic effects of the liquid crystal layer, the liquid crystal molecules align along the friction direction of the alignment layer (parallel alignment) when no electric field is present, and rotate along the direction of the electric field (perpendicular alignment) when an electric field is applied. By adjusting the driving voltage, the control component can cause the liquid crystal molecules to rotate, thereby continuously adjusting the equivalent refractive index of the liquid crystal layer. When the adjustable angle between the waveguide lens and the beam splitter changes, the incident angle of the light will shift. The control component adjusts the equivalent refractive index of the liquid crystal layer according to this change, causing refraction and deflection of the light as it passes through the liquid crystal layer. This compensates for the shift in the incident angle caused by the change in the adjustable angle, ensuring that the incident angle of the light entering the waveguide lens remains within the designed angle range. This guarantees stable diffraction efficiency in the coupling region of the waveguide lens and avoids problems such as uneven brightness between the left and right eyes and deterioration of image quality due to angle changes.

[0024] Optionally, the control component includes an angle sensor and a control circuit. The angle sensor is disposed on the side wall of the beam splitter module. The control circuit is electrically connected to the angle sensor, the first transparent electrode, and the second transparent electrode, respectively. The control circuit can apply a corresponding driving voltage to the liquid crystal coupling layer to change the equivalent refractive index of the liquid crystal layer according to the adjustable angle detected by the angle sensor.

[0025] By adopting the above technical solution, when the adjustable angle between the waveguide lens and the beam splitter changes, the angle sensor can detect the specific value of the adjustable angle in real time. This value is then fed back to the control circuit, which calculates the driving voltage to be applied to the liquid crystal coupling layer based on a preset angle-voltage correspondence. After the control circuit applies the corresponding driving voltage to the first and second transparent electrodes, the liquid crystal molecules in the liquid crystal layer rotate under the influence of the electric field, thereby changing the equivalent refractive index of the liquid crystal layer. This causes refraction and deflection when light passes through the liquid crystal coupling layer, compensating for the shift in the incident angle of light caused by the change in the adjustable angle. This ensures that the incident angle of light entering the waveguide lens remains within the designed angle range, thus stabilizing the diffraction efficiency of the waveguide lens coupling region and ensuring uniform brightness and stable image quality for both eyes under different angle settings. Simultaneously, the control circuit has low additional power consumption, minimizing the increase in system energy consumption.

[0026] Optionally, the coupling region of the waveguide lens is provided with a wide response grating, which includes at least three layers of volume holographic gratings stacked along the thickness direction of the waveguide lens. Each layer of the volume holographic grating has the same grating period and different tilt angles of the grating stripes, so that each layer of the volume holographic grating has a different Bragg angle.

[0027] By employing the above technical solution, when light is incident at different angles, volume holographic gratings with different Bragg angles can achieve high diffraction efficiency at their respective corresponding incident angles. For example, when the incident angle of light is at a certain angle, the volume holographic grating with the corresponding Bragg angle is in its most efficient state, responsible for completing the coupled diffraction. As the adjustable angle changes within the range of 0-6 degrees, the incident angle of light will also change accordingly, but there will always be one or more volume holographic gratings that can maintain high diffraction efficiency at that incident angle. Thus, high diffraction efficiency is maintained for different incident angles within the preset angle range, reducing diffraction efficiency fluctuations caused by changes in the adjustable angle, and improving the imaging quality and stability of the system under different angle settings.

[0028] Optionally, the difference in Bragg angle between any two adjacent volume holographic gratings is 1-3 degrees, and the coverage range of the Bragg angle of each volume holographic grating corresponds to the range of incident angle change when the adjustable angle changes within the range of 0-6 degrees.

[0029] By adopting the above technical solution, when the adjustable angle changes within the range of 0-6 degrees, since the difference in Bragg angle between two adjacent volume holographic gratings is 1-3 degrees, and the Bragg angle of each volume holographic grating covers the range of incident angle changes corresponding to this adjustable angle change, the light can always find a region on a certain volume holographic grating that matches its Bragg angle, regardless of how the adjustable angle changes. Thus, under different adjustable angles, there can be a suitable volume holographic grating to efficiently couple and diffract the light, ensuring that the diffraction efficiency of the light coupled into the waveguide lens fluctuates little when the adjustable angle changes. This achieves a high and stable diffraction efficiency in the waveguide lens coupling area within the adjustable angle range of 0-6 degrees, ensuring uniform brightness and stable imaging quality for both eyes under different angle settings.

[0030] Secondly, this application provides AR glasses, which adopt the following technical solution:

[0031] An AR glasses system includes an eyeglass frame and a single-optical binocular near-eye display system as described in any one of the above descriptions.

[0032] In summary, this application includes at least one of the following beneficial technical effects:

[0033] 1. By setting an angle compensation module, the incident angle shift of light is automatically compensated when the angle between the beam splitter and the waveguide lens changes, so that the diffraction efficiency of the waveguide lens remains stable, thereby maintaining stable imaging brightness and quality after angle adjustment.

[0034] 2. The elastic coupling block achieves angle compensation through passive adaptive deformation, reducing the incident angle shift when light reaches the waveguide lens, thereby reducing the fluctuation of diffraction efficiency and significantly improving imaging quality;

[0035] 3. The liquid crystal coupling layer achieves precise angle compensation through active electronic control, ensuring that the incident angle of light entering the waveguide lens remains within the design angle range, guaranteeing uniform brightness and stable image quality for both eyes under different angle settings, and with low additional power consumption. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the overall structure of a single-optical binocular near-eye display system according to Embodiment 1 of this application.

[0037] Figure 2 This is a top view of a single-optical binocular near-eye display system with an adjustable included angle of 0, as described in Embodiment 1 of this application.

[0038] Figure 3 This is a top view of a single-optical binocular near-eye display system with an adjustable included angle that is not 0, as described in Embodiment 1 of this application.

[0039] Figure 4It is along in Embodiment 2 of this application Figure 1 A partial structural cross-sectional view of line AA in the middle.

[0040] Figure 5 This is a partial structural schematic diagram of a single-optical binocular near-eye display system according to Embodiment 3 of this application.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Optomechanical module; 2. Beam splitting module; 21. First waveguide substrate; 22. First coupling region; 23. Internal beam splitting structure; 24. First coupling region; 3. Waveguide lens; 31. Second waveguide substrate; 32. Second coupling region; 33. Pupil expansion region; 34. Second coupling region; 4. Angle compensation module; 41. Elastic coupling block; 411. First optical surface; 412. Second optical surface; 413. Light-absorbing coating; 42. Liquid crystal coupling layer; 421. First substrate; 422. First transparent electrode; 423. First alignment layer; 424. Liquid crystal layer; 425. Second alignment layer; 426. Second transparent electrode; 427. Second substrate; 43. Control component; 431. Angle sensor; 5. Wide response grating. Detailed Implementation

[0043] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0044] This application discloses a single-optical binocular near-eye display system.

[0045] It should be noted that, in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] Example 1: Refer to Figure 1 and Figure 2A single-optical-engine binocular near-eye display system includes an optical-mechanical module 1, a beam splitter module 2, waveguide lenses 3, and an angle compensation module 4. The optical-mechanical module 1 outputs an image beam. The beam splitter module 2 is positioned in the light-emitting direction of the optical-mechanical module 1 to split the image beam into a first beam and a second beam. Two sets of waveguide lenses 3 are provided, with the first and second beams respectively incident on the two sets of waveguide lenses 3. The angle compensation module 4 is positioned between the waveguide lenses 3 and the beam splitter module 2 to compensate for the deviation of the light incident angle, ensuring that the incident angle of the light entering the waveguide lenses 3 remains within the designed angle range. This allows the system to maintain good optical coupling efficiency even when the angle changes, guaranteeing the brightness and quality of the image.

[0047] The light output port of the optical engine module 1 faces the beam splitter module 2, and there is an air gap between the light output port of the optical engine module 1 and the beam splitter module 2. The optical engine module 1 has a built-in collimating lens group, so that the emitted beam is a near-parallel beam. In this embodiment, the optical engine module 1 is an LCoS micro projection optical engine, and the optical engine module 1 is located above the bridge area of ​​the eyeglass frame and is fixedly mounted on the eyeglass frame by a rigid bracket. The bracket and the eyeglass frame are connected by screws. In other embodiments, the optical engine module 1 can also be replaced by other projection devices that can produce high-quality image beams, as long as they can meet the system's requirements for image beam output.

[0048] The beam splitter module 2 is fixed to the nose bridge support of the eyeglass frame by adhesive bonding or mechanical clamping, and is connected to the waveguide lens 3 through the angle compensation module 4. The beam splitter module 2 includes a first waveguide substrate 21, a first coupling region 22, an internal beam splitting structure 23, and two first coupling out regions 24. The first waveguide substrate 21 is made of high refractive index optical glass plate, such as with a refractive index between 1.7 and 2.0.

[0049] The first coupling region 22 is located at the upper center of the first waveguide substrate 21, and a surface relief grating is provided in the first coupling region 22 to receive the image beam output by the optomechanical module 1. In other embodiments, the surface relief grating can also be replaced by a volume holographic grating or a coupling prism.

[0050] An internal beam-splitting structure 23 is disposed on the first waveguide substrate 21 and located below the first coupling region 22, which can split the coupled light into two paths. In this embodiment, the internal beam-splitting structure 23 adopts a beam-splitting grating, which can split the incident light into diffracted light in two directions through diffraction. In other embodiments, the internal beam-splitting structure 23 may also adopt a beam-splitting film or a beam-splitting mirror.

[0051] Two first coupling regions 24 are respectively disposed on the first waveguide substrate 21 and symmetrically arranged along the inner beam splitting structure 23, so that the two first coupling regions 24 can couple and output the beams that propagate to the left and right after beam splitting. In this embodiment, a surface relief grating or a volume holographic grating is disposed in the first coupling region 24.

[0052] The propagation direction of the first beam is defined as the first optical path, and the propagation direction of the second beam is defined as the second optical path. One set of waveguide mirrors 3 is disposed in the first optical path, and another set of waveguide mirrors 3 is disposed in the second optical path.

[0053] The waveguide lens 3 includes a second waveguide substrate 31 and a second coupling region 32, a pupil expansion region 33, and a second coupling out region 34 disposed on the second waveguide substrate 31. The second coupling region 32 is located on the side of the second waveguide substrate 31 closest to the first waveguide substrate 21, and the second coupling region 32 and the first coupling out region 24 are disposed opposite each other in the horizontal direction. A coupling grating is disposed in the second coupling region 32.

[0054] The pupil expansion region 33 is located in the middle of the second waveguide substrate 31, and a deflection grating is provided within the pupil expansion region 33 to perform one-dimensional pupil expansion of light. The second coupling region 34 is located on the side of the second waveguide substrate 31 away from the first waveguide substrate 21 and corresponds to the user's pupil position. A coupling grating is provided within the second coupling region 34 to couple the light propagating within the second waveguide substrate 31 to the user.

[0055] In this embodiment, an adjustable angle θ is formed between the first waveguide substrate 21 and the second waveguide substrate 31. The adjustable angle θ is the angle at which the second waveguide substrate 31 rotates relative to the first waveguide substrate 21 about the vertical axis in the horizontal plane, that is, the angle at which the second waveguide substrate 31 opens outward.

[0056] The adjustable angle θ has an adjustment range of 0-6 degrees. When the adjustable angle θ is equal to 0 degrees, the first waveguide substrate 21 and the second waveguide substrate 31 are coplanar or parallel; when the adjustable angle θ is greater than 0 degrees, the second waveguide substrate 31 is tilted outward relative to the first waveguide substrate 21. The two second waveguide substrates 31 can be adjusted independently, that is, the two adjustable angles θ can be different values ​​to adapt to the asymmetrical facial contours.

[0057] The angle compensation module 4 is provided in two sets. One set of angle compensation module 4 is located between a second waveguide substrate 31 and a first waveguide substrate 21 and in the first optical path. The other set of angle compensation module 4 is located between another second waveguide substrate 31 and a first waveguide substrate 21 and in the second optical path.

[0058] The angle compensation module 4 includes an elastic coupling block 41, which is disposed between the waveguide lens 3 and the beam splitter module 2. In this embodiment, the elastic coupling block 41 is an optical-grade elastic transparent body made of optical-grade polydimethylsiloxane (PDMS), with a refractive index of 1.43, a Young's modulus of 8 MPa, and a visible light transmittance of 93%, thus giving the elastic coupling block 41 good optical performance and elasticity. In other embodiments, the elastic coupling block 41 may also be made of materials such as optical-grade thermoplastic polyurethane elastomer (TPU).

[0059] The elastic coupling block 41 has a first optical surface 411 and a second optical surface 412 disposed opposite to each other. The first optical surface 411 is bonded to the coupling surface of the first coupling region 24 on the first waveguide substrate 21 by optical-grade UV curable adhesive, and the adhesive layer has a thickness of 10 μm. The refractive index of the adhesive layer matches the refractive index of the elastic coupling block 41, with a difference of less than 0.05. The bonding area is rectangular, covering the position directly opposite the first coupling region 24, and extending outward by a margin of 3 mm.

[0060] The second optical surface 412 is bonded to the coupling surface of the second coupling region 32 on the second waveguide substrate 31 using optical-grade UV-curable adhesive. The bonding method, adhesive layer thickness, and bonding area are the same as those of the first optical surface 411. The bonding area covers the position directly opposite the second coupling region 32 and extends outward by a margin of 3 mm.

[0061] The sides of the elastic coupling block 41 are not bonded to any structure and remain free surfaces, allowing the elastic coupling block 41 to deform freely when the adjustable included angle θ changes. Furthermore, the sides of the elastic coupling block 41 are coated with a black light-absorbing coating 413 to absorb stray light that may leak from the sides.

[0062] The refractive index of the elastic coupling block 41 is greater than the air refractive index of 1.0 and less than the refractive index of the first waveguide substrate 21 and the second waveguide substrate 31, so that the light still satisfies the total internal reflection condition inside the first waveguide substrate 21 and the second waveguide substrate 31, and the light will not leak from the side of the waveguide due to the presence of the elastic coupling block 41.

[0063] Reference Figure 1 and Figure 2 When the adjustable angle θ is 0, the coupling surface of the first waveguide substrate 21 is parallel to the coupling surface of the second waveguide substrate 31. At this time, the first optical surface 411 and the second optical surface 412 are parallel to each other, and the elastic coupling block 41 is in the shape of a parallel plate.

[0064] After the light rays are coupled out from the first coupling region 24, when they pass through the elastic coupling block 41 which is in the shape of a parallel plate, the direction of light propagation does not change because the first optical surface 411 and the second optical surface 412 are parallel to each other. Only a parallel displacement occurs, so that the light rays are incident on the second coupling region 32 at the optimal angle of 45° (i.e., the Bragg angle), at which point the diffraction efficiency is the highest.

[0065] Reference Figure 1 and Figure 3When the adjustable angle θ increases to Δθ, the tilt angle of the second waveguide substrate 31 relative to the first waveguide substrate 21 is Δθ. Since the first optical surface 411 is bonded to the coupling surface of the first waveguide substrate 21 and remains stationary, the second optical surface 412 tilts Δθ together with the second waveguide substrate 31, resulting in an angular deviation Δθ between the second optical surface 412 and the first optical surface 411. Due to the angular difference between the first optical surface 411 and the second optical surface 412, the elastic coupling block 41 undergoes shear deformation, transforming from a parallel plate into a wedge shape, with the wedge angle approximately equal to Δθ.

[0066] The deformed elastic coupling block 41 forms a wedge-shaped prism with a wedge angle approximately equal to Δθ. According to the refraction and deflection formula of a thin wedge prism, the deflection angle generated when light passes through the wedge is (refractive index - 1) × wedge angle = (1.43 - 1) × Δθ = 0.43 × Δθ. This deflection angle partially compensates for the incident angle shift Δθ caused by the change in the adjustable angle θ, reducing the actual incident angle shift when the light reaches the second coupling region 32 from Δθ to approximately 0.57 × Δθ, thereby mitigating the decrease in diffraction efficiency.

[0067] In this embodiment, the overall diffraction efficiency is 88% when the adjustable angle θ is 0 degrees; when the adjustable angle θ is 2 degrees, the incident angle shift is approximately 1.14 degrees after compensation by the elastic coupling block 41, and the overall diffraction efficiency is approximately 78%; when the adjustable angle θ is 4 degrees, the incident angle shift is approximately 2.28 degrees after compensation, and the overall diffraction efficiency is approximately 65%. Compared to the approximately 40% diffraction efficiency when the adjustable angle θ is 4 degrees without compensation, the elastic coupling block 41 improves the diffraction efficiency by approximately 25 percentage points.

[0068] It should be noted that in this embodiment, within the small angular deformation range of 0-6 degrees, the PDMS material is within the linear elastic deformation range, and the deformed first optical surface 411 and second optical surface 412 still remain approximately planar. Finite element analysis estimates that when the adjustable angle θ is 6 degrees, the non-planarity of the optical surface (i.e., the maximum deviation of each point on the optical surface from the ideal plane) is less than 5 μm, and the corresponding wavefront error is less than λ / 10 (calculated with a visible light center wavelength of 550 nm). The impact of this wavefront error on imaging quality is negligible.

[0069] In addition to the passive compensation method of the elastic coupling block 41 mentioned above, angle compensation can also be achieved in other ways, such as: using a mechanical wedge prism with an adjustable wedge angle, adjusting the wedge angle of the wedge prism according to the change of the adjustable angle θ through a mechanical mechanism; or using an electro-optic crystal (such as a lithium niobate crystal), changing the refractive index of the crystal by applying an electric field to achieve light deflection compensation. However, the above methods have problems such as complex structure, large size, and high cost, and are not as simple and efficient as the passive adaptive method of the elastic coupling block 41.

[0070] The implementation principle of a single-optical-engine binocular near-eye display system according to an embodiment of this application is as follows: The image beam generated by the optical-engine module 1 is coupled into the interior of the first waveguide substrate 21 through the first coupling region 22, and then split into two paths by the internal beam splitting structure 23, which propagate to the left and right respectively, and are coupled out from the two first coupling out regions 24 respectively. The coupled light rays pass through the elastic coupling block 41 and enter the second coupling region 32. When the adjustable angle θ changes, the elastic coupling block 41 automatically undergoes shear deformation to form a wedge, passively compensating for the incident angle shift through refraction and deflection. After the light rays are coupled into the second waveguide substrate 31 through the second coupling region 32, they undergo pupil dilation in the pupil dilation region 33, and finally are coupled out from the second coupling out region 34 to the user's eye, realizing a single-optical-engine binocular AR display.

[0071] Example 2: Refer to Figure 1 and Figure 4 The difference between this embodiment and embodiment 1 is that the coupling grating in the second coupling region 32 is replaced with a wide response grating 5.

[0072] The wide-response grating 5 includes at least three layers of volume holographic gratings stacked along the thickness direction of the second waveguide substrate 31. In this embodiment, the volume holographic gratings are provided in three layers, and adjacent layers of volume holographic gratings are bonded together by optical adhesive.

[0073] Each layer of the volumetric holographic grating has the same grating period but different grating fringes tilt angles, resulting in different Bragg angles for each layer. The difference in Bragg angle between two adjacent layers is 1-3 degrees, and the coverage range of the Bragg angle of each layer corresponds to the range of incident angle variation when the adjustable angle θ varies within the range of 0-6 degrees.

[0074] The Bragg angle of the first-layer volume holographic grating is the incident angle at the design center minus an angular offset, such as 1-3 degrees; the Bragg angle of the second-layer volume holographic grating is the incident angle at the design center; the Bragg angle of the third-layer volume holographic grating is the incident angle at the design center plus the angular offset.

[0075] For example, the first-layer volume holographic grating has a Bragg angle of 43 degrees, a thickness of 12 μm, and a peak diffraction efficiency of 88%; the second-layer volume holographic grating has a Bragg angle of 45 degrees, a thickness of 12 μm, and a peak diffraction efficiency of 90%; and the third-layer volume holographic grating has a Bragg angle of 47 degrees, a thickness of 12 μm, and a peak diffraction efficiency of 88%.

[0076] The three-layer volume holographic gratings have the same grating period of 430 nm to ensure consistent diffraction direction. The grating fringes of the three layers are tilted at different angles, corresponding to Bragg angles of 43 degrees, 45 degrees, and 47 degrees respectively. The difference in Bragg angle between adjacent layers is 2 degrees.

[0077] It should be noted that in this embodiment, the total thickness of the three-layer volume holographic grating is 36μm (excluding the optical adhesive layer). After adding the two optical adhesive layers (each layer is about 5μm), the total thickness is about 46μm, which is much smaller than the thickness of the second waveguide substrate 31 of 500μm and will not significantly affect the overall thickness of the waveguide lens 3.

[0078] The overall angular response range of the three-layer volume holographic grating is 41-49 degrees (8 degrees at half maximum and full width at half maximum). When the adjustable angle θ is 0, the light is incident at a 45-degree angle, and the second-layer volume holographic grating is in its most efficient state. The coupling diffraction is mainly completed by the second-layer volume holographic grating, and the overall diffraction efficiency is about 88%.

[0079] When the adjustable angle θ is 2 degrees, the incident angle shift is approximately 1.14 degrees after compensation by the elastic coupling block 41, and the actual incident angle is approximately 46.14 degrees. The second and third volume holographic gratings together provide high diffraction efficiency, with a combined diffraction efficiency of approximately 83%. When the adjustable angle θ is 4 degrees, the incident angle shift is approximately 2.28 degrees after compensation, and the actual incident angle is approximately 47.28 degrees. The third volume holographic grating is in a state close to its maximum efficiency, with a combined diffraction efficiency of approximately 74%.

[0080] The implementation principle of Example 2 is as follows: the elastic coupling block 41 provides about 43% angle compensation, and the wide response grating 5 maintains a high diffraction efficiency in the remaining angle offset range. The combination of the two makes the overall diffraction efficiency fluctuation within 14% in the adjustable angle θ range of 0-6 degrees.

[0081] Example 3: Reference Figure 1 and Figure 5 The difference between this embodiment and embodiment 1 is that the angle compensation module 4 also includes a liquid crystal coupling layer 42 and a control component 43.

[0082] Two sets of liquid crystal coupling layers 42 are provided, each corresponding to one of the two elastic coupling blocks 41. The liquid crystal coupling layers 42 are embedded inside the corresponding elastic coupling blocks 41, and the area of ​​the liquid crystal coupling layers 42 is smaller than the cross-sectional area of ​​the elastic coupling blocks 41.

[0083] The liquid crystal coupling layer 42 includes a first substrate 421, a first transparent electrode 422, a first alignment layer 423, a liquid crystal layer 424, a second alignment layer 425, a second transparent electrode 426, and a second substrate 427, which are stacked sequentially. The first substrate 421 is disposed near the first optical surface 411, and the second substrate 427 is disposed near the second optical surface 412.

[0084] The first substrate 421 and the second substrate 427 are flexible PET film substrates, which makes the liquid crystal coupling layer 42 flexible enough to adapt to the deformation of the elastic coupling block 41 within a small angle range, and will not significantly limit the overall deformation capability of the elastic coupling block 41.

[0085] The first transparent electrode 422 and the second transparent electrode 426 are ITO (indium tin oxide) thin film electrodes used to apply voltage to control the liquid crystal layer 424. The first alignment layer 423 and the second alignment layer 425 are polyimide (PI) thin films, which are rubbed aligned to control the initial alignment direction of the liquid crystal molecules. The liquid crystal layer 424 is a nematic liquid crystal material, in which the liquid crystal molecules align along the rubbing direction of the alignment layer when there is no electric field, and rotate along the direction of the electric field when an electric field is applied.

[0086] In this embodiment, the first transparent electrode 422 and the second transparent electrode 426 are respectively led out through a flexible circuit board. The flexible circuit board is arranged along the edge of the beam splitter module 2 or the corresponding waveguide lens 3, without obstructing the optical path. The other end of the flexible circuit board is connected to the control component 43.

[0087] The control component 43 includes an angle sensor 431 and a control circuit. The angle sensor 431 is disposed on the sidewall of the first waveguide substrate 21. In this embodiment, the angle sensor 431 is a Hall effect angle sensor, which detects the current adjustable angle θ by means of changes in the magnetic field. In other embodiments, the angle sensor 431 may also be a resistive angle sensor or a photoelectric encoder.

[0088] The control circuit includes a low-power MCU and a voltage drive circuit, integrated on a flexible circuit board. The control circuit is mounted on the inner side of the nose bridge support of the eyeglass frame, above the first waveguide substrate 21, and is fixed to the inner wall of the nose bridge support by adhesive bonding.

[0089] The control circuit is electrically connected to the first transparent electrode 422 and the second transparent electrode 426 through a flexible circuit board. After the flexible circuit board is laid along the upper edge of the first waveguide substrate 21, it extends to the liquid crystal coupling layer 42 inside the elastic coupling block 41 on both sides, without blocking the light path.

[0090] The control circuit is electrically connected to the angle sensor 431 via a signal line that runs along the edge of the first waveguide substrate 21. The control circuit is powered by a battery installed inside the temple of the eyeglasses, connected via a power line that runs along the eyeglass frame.

[0091] It should be noted that in this embodiment, the MCU can determine the required driving voltage based on a pre-stored angle and voltage lookup table. The specific method for establishing the angle and voltage lookup table is as follows: During the product factory calibration stage, the adjustable angle θ is gradually increased from 0 degrees to 6 degrees in 0.5-degree increments. At each angle, the optical power at the output end of the waveguide lens 3 is measured using an optical power meter. The driving voltage V of the liquid crystal coupling layer 42 is adjusted to maximize the optical power. The optimal driving voltage V at that angle is recorded, forming an angle-voltage correspondence table, which is then stored in the MCU's non-volatile memory.

[0092] The specific angle and voltage data are shown in the table below. It should be noted that the following data is the combined result of the passive compensation of the elastic coupling block 41 and the active compensation of the liquid crystal coupling layer 42:

[0093] Adjustable angle θ Drive voltage V Liquid crystal equivalent refractive index Overall diffraction efficiency (%) 0 0 1.74 87 1 0.8 1.70 86 2 1.5 1.66 85 3 2.2 1.62 84 4 3.0 1.58 83 5 3.6 1.55 82 6 4.2 1.53 82

[0094] The implementation principle of Example 3 is as follows: Angle sensor 431 detects the current adjustable angle θ value and outputs it to MCU; MCU calculates the change Δθ of the adjustable angle θ relative to the initial value of 0 degrees; MCU determines the required driving voltage according to the pre-stored angle and voltage lookup table; voltage driving circuit applies voltage between the first transparent electrode 422 and the second transparent electrode 426; liquid crystal molecules in liquid crystal layer 424 rotate under the action of electric field, causing the equivalent refractive index of liquid crystal layer 424 to change from the extraordinary refractive index to the ordinary refractive index to the target value; when light passes through liquid crystal layer 424, it is refracted and deflected due to the change in refractive index, compensating for the incident angle shift.

[0095] This application also discloses an AR glasses embodiment.

[0096] Reference Figure 1 An AR glasses system includes an eyeglass frame and the aforementioned monooptic binocular near-eye display system. The optical engine module 1 is rigidly mounted above the bridge of the eyeglass frame via a bracket, with its light-emitting port facing downwards and pointing towards the first coupling region 22 of the first waveguide substrate 21. In other embodiments, the optical engine module 1 may also be mounted at the base of the temple of the eyeglass frame.

[0097] The first waveguide substrate 21 is fixedly mounted on the nose bridge support by adhesive bonding. One second waveguide substrate 31 is mounted in the left frame of the eyeglasses frame, and another second waveguide substrate 31 is mounted in the right frame of the eyeglasses frame. The second waveguide substrate 31 and the first waveguide substrate 21 are connected at an adjustable angle by an elastic coupling block 41.

[0098] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A single-optical binocular near-eye display system, characterized in that, include: Optomechanical module (1), used to output image beam; The beam splitting module (2) is set in the light output direction of the optical-mechanical module (1) to split the image beam into a first beam and a second beam, and the propagation direction of the first beam is defined as the first optical path and the propagation direction of the second beam is defined as the second optical path. Two sets of waveguide lenses (3) are provided. One set of waveguide lenses (3) is provided in the first optical path, and the other set of waveguide lenses (3) is provided in the second optical path. An adjustable angle is formed between the waveguide lenses (3) and the beam splitting module (2). Angle compensation module (4) is provided in two sets. One set of angle compensation module (4) is located between one waveguide lens (3) and the beam splitting module (2) and in the first optical path. The other set of angle compensation module (4) is located between another waveguide lens (3) and the beam splitting module (2) and in the second optical path. The angle compensation module (4) is used to compensate for the light incident angle shift caused by the change of the adjustable angle when the adjustable angle changes, so that the incident angle shift when the light couples into the waveguide lens (3) is reduced.

2. The single-optical binocular near-eye display system according to claim 1, characterized in that: The angle compensation module (4) includes an elastic coupling block (41), which is disposed between the waveguide lens (3) and the beam splitting module (2). The elastic coupling block (41) has a first optical surface (411) and a second optical surface (412) disposed opposite to each other. The first optical surface (411) is connected to the beam splitting module (2), and the second optical surface (412) is connected to the waveguide lens (3). When the adjustable angle is zero, the first optical surface (411) and the second optical surface (412) are parallel, and the elastic coupling block (41) is in the form of a parallel plate. When the adjustable angle is greater than zero, the second optical surface (412) tilts with the waveguide lens (3), and the elastic coupling block (41) undergoes shear deformation to form a wedge shape, which deflects the light passing through the elastic coupling block (41) to compensate for the incident angle shift.

3. The single-optical binocular near-eye display system according to claim 2, characterized in that: The elastic coupling block (41) is made of optical grade polydimethylsiloxane or optical grade thermoplastic polyurethane elastomer, and the side of the elastic coupling block (41) is coated with a light-absorbing coating (413).

4. The single-optical binocular near-eye display system according to claim 3, characterized in that: The refractive index of the elastic coupling block (41) is greater than that of air and less than that of the beam splitter module (2) and the waveguide lens (3).

5. The single-optical binocular near-eye display system according to claim 2, characterized in that: The angle compensation module (4) includes a liquid crystal coupling layer (42) and a control component (43). The liquid crystal coupling layer (42) is embedded in the elastic coupling block (41). The control component (43) is disposed on the side wall of the beam splitting module (2) and electrically connected to the liquid crystal coupling layer (42). The control component (43) is used to control the equivalent refractive index of the liquid crystal coupling layer (42) so that light is refracted and deflected when passing through the liquid crystal coupling layer (42) to compensate for the incident angle shift.

6. The single-optical binocular near-eye display system according to claim 5, characterized in that: The liquid crystal coupling layer (42) includes a first substrate (421), a first transparent electrode (422), a first alignment layer (423), a liquid crystal layer (424), a second alignment layer (425), a second transparent electrode (426), and a second substrate (427) stacked sequentially within the elastic coupling block (41). The first substrate (421) is disposed close to the first optical surface (411), and the second substrate (427) is disposed close to the second optical surface (412). The control component (43) is electrically connected to the first transparent electrode (422) and the second transparent electrode (426), respectively. The control component (43) is used to adjust the equivalent refractive index of the liquid crystal layer (424).

7. The single-optical binocular near-eye display system according to claim 6, characterized in that: The control component (43) includes an angle sensor (431) and a control circuit. The angle sensor (431) is disposed on the side wall of the beam splitting module (2). The control circuit is electrically connected to the angle sensor (431), the first transparent electrode (422) and the second transparent electrode (426) respectively. The control circuit can apply a corresponding driving voltage to the liquid crystal coupling layer (42) to change the equivalent refractive index of the liquid crystal layer (424) according to the adjustable angle detected by the angle sensor (431).

8. The single-optical binocular near-eye display system according to claim 1, characterized in that: The coupling region of the waveguide lens (3) is provided with a wide response grating (5). The wide response grating (5) includes at least three layers of volume holographic gratings stacked along the thickness direction of the waveguide lens (3). The grating period of each layer of the volume holographic grating is the same and the tilt angle of the grating stripes is different, so that each layer of the volume holographic grating has a different Bragg angle.

9. The single-optical binocular near-eye display system according to claim 8, characterized in that: The difference in Bragg angle between any two adjacent layers of the volume holographic grating is 1-3 degrees, and the coverage range of the Bragg angle of each layer of the volume holographic grating corresponds to the range of incident angle change when the adjustable angle changes within the range of 0-6 degrees.

10. An AR glasses, characterized in that: Includes eyeglass frames and a single-vision binocular near-eye display system as described in any one of claims 1-9.

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