Reflection type AR diffraction optical waveguide lens

Abstract

The invention relates to a reflective AR diffractive optical waveguide lens, which comprises a waveguide substrate, an input diffractive optical element, an output diffractive optical element, a low refractive index filling layer, a sub-wavelength diffractive microstructure and / or a diffractive optical film, and is characterized in that the input diffractive optical element couples a light beam into the waveguide substrate; coupled light beams are totally reflected in the waveguide substrate and then are coupled out by the output diffractive optical element step by step, the low-refractive filling layer is embedded in a grating gap between the input diffractive optical element and the output diffractive optical element, and the height of the low-refractive filling layer exceeds that of the input diffractive optical element and the output diffractive optical element. And the sub-wavelength diffraction microstructure and / or the diffraction optical film are / is arranged on the low-refractive-index filling layer and are / is arranged opposite to the output diffraction optical element. According to the invention, an air capping plate layer for protecting a grating in an AR lens is replaced, the size of the lens is reduced, and the sub-wavelength diffraction microstructure and / or the diffraction optical film on the low-refraction filling layer can solve the problems of rainbow lines, light leakage, transmittance and the like caused by diffraction optical waveguides on the basis of not influencing the optical performance.

Description

Technical Field

[0001] This invention relates to the technical field of optical elements, and in particular to a reflective AR diffractive waveguide lens. Background Technology

[0002] AR glasses, as a technology that integrates virtual information with the real world, have always attracted much attention. Diffractive waveguides, due to their mass production capabilities and yield rates, have become the mainstream approach for AR glasses. However, issues such as the size, rainbow effect, light leakage, and transmittance of diffractive waveguides hinder the commercialization of AR glasses. Although existing technologies have proposed various improvement methods through patent strategies, most only address single or partial problems, lacking a comprehensive solution that systematically addresses all core pain points. Here, we propose an integrated reflective lens architecture combining diffractive waveguides, a filling layer, and a microstructure, which can simultaneously solve problems related to waveguide size, weak rainbow effect, light leakage, and transmittance without compromising optical performance.

[0003] Chinese Patent CN114265138B discloses a diffractive waveguide device for eliminating rainbow effects. The device includes a light engine, a coupling grating, a waveguide assembly, an adjustment mechanism, and an output grating. The coupling grating, adjustment mechanism, and output grating are all fitted into the waveguide assembly. Specifically: the coupling grating couples the light emitted by the light engine into the waveguide assembly; the adjustment mechanism, a volume Bragg grating, is positioned opposite the output grating and reflects light within a preset angle range from the ambient light entering the waveguide assembly, causing the ambient light to exhibit zero-order diffraction after passing through the output grating, thus eliminating the rainbow effect; and the output grating couples the light transmitted through the waveguide assembly out to the human eye. However, the aforementioned diffractive waveguide, with a volume Bragg grating opposite the output grating, only reflects ambient light at a specific angle, failing to improve rainbow patterns caused by ambient light incident at large angles.

[0004] Chinese Patent Publication No. CN118091820A discloses a diffractive waveguide, which includes a waveguide substrate and a coupling grating region, a coupling out grating region, and a reflecting region disposed on the surface of the waveguide substrate. Light enters the waveguide substrate through the coupling grating region and undergoes total internal reflection within the waveguide substrate. After total internal reflection, the light reaches the coupling out grating region, generating first diffracted light and second diffracted light. The first diffracted light couples out of the waveguide substrate and enters the human eye. The reflecting region is disposed on the surface from which the second diffracted light exits the waveguide substrate, corresponding to the coupling out grating region. After reaching the reflecting region, the second diffracted light is selectively reflected back to the waveguide substrate. While the addition of a reflecting region opposite the coupling out grating in this diffractive waveguide achieves a light leakage prevention effect, light that does not undergo total internal reflection after diffraction through the coupling out grating will pass through the reflecting region and re-interact with the coupling out grating before entering the human eye, thus affecting the uniformity of the eye movement range.

[0005] A recent Chinese patent application (CN222280875U) disclosed an optical waveguide lens, comprising at least two glass substrates, an optical waveguide sheet disposed between two adjacent glass substrates, a grating structure disposed on at least one surface of the optical waveguide sheet, and a filling layer embedded in the grating gaps of the grating structure. The glass substrates are composed of low-refractive-index glass, the optical waveguide sheet and grating structure are composed of silicon carbide, and the filling layer is composed of a low-refractive-index optical coating material. Furthermore, the outer surfaces of the filling layer and the grating structure are approximately on the same plane, and / or the filling layer covers the outer surface of the grating structure. This optical waveguide lens uses a low-refractive-index glass-diffractive waveguide-low-refractive-index glass approach, and uses a low-refractive-index coating material to fill the grating gaps, allowing the low-refractive-index glass to bond with the optical waveguide and removing the air layer to reduce the lens thickness. However, it still involves two layers of glass, limiting the improvement in thickness. Moreover, these patents address specific problems without providing a systematic and complete solution. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a reflective AR diffractive waveguide lens that addresses the above-mentioned shortcomings of the prior art. It not only replaces the air cover layer of the protective grating in the AR lens, reducing the size of the lens, but also solves the problems of rainbow patterns, light leakage and transmittance caused by diffractive waveguides by the subwavelength diffractive microstructure and / or diffractive optical film on the low-refractive filling layer without affecting the optical performance.

[0007] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0008] A reflective AR diffractive waveguide lens includes a waveguide substrate, an input diffractive optical element, an output diffractive optical element, a low-refractive filling layer, and a subwavelength diffractive microstructure and / or a diffractive optical thin film. The input diffractive optical element couples a light beam into the waveguide substrate. After total internal reflection in the waveguide substrate, the coupled light beam is coupled out stepwise by the output diffractive optical element. The low-refractive filling layer is embedded in the grating gap between the input and output diffractive optical elements and has a height exceeding that of the input and output diffractive optical elements. The subwavelength diffractive microstructure and / or diffractive optical thin film are arranged on the low-refractive filling layer and are arranged relative to the output diffractive optical element.

[0009] Furthermore, the waveguide substrate is one or a combination of several of optical glass, optical resin, Si3N4 and SiC;

[0010] And / or, the refractive index of the waveguide substrate exceeds 1.7;

[0011] And / or, the thickness of the waveguide substrate is 0.5~1.0 mm.

[0012] Furthermore, the input diffractive optical element and the output diffractive optical element are one or more of the following: straight grating, blazed grating, tilted grating, double-ridge grating, and one-dimensional multilayer grating;

[0013] And / or, the input diffractive optical element and the output diffractive optical element are respectively closely attached to the surface of the waveguide substrate or embedded in the material of the waveguide substrate;

[0014] And / or, the input diffractive optical element and the output diffractive optical element are one or a combination of several of optical glass, optical resin, Si3N4, TiO2 and SiC;

[0015] And / or, the refractive index of the input diffractive optical element exceeds 1.7, and the refractive index of the output diffractive optical element exceeds 1.7.

[0016] Furthermore, the input diffractive optical element is configured as a one-dimensional coupling grating; wherein,

[0017] The height of the one-dimensional coupling grating is 10~500nm; preferably 20~60nm.

[0018] And / or, the duty cycle of the one-dimensional coupling grating is 20~100%; preferably 40~80%;

[0019] And / or, the period of the one-dimensional coupling grating is 150~500nm; preferably 280~330nm;

[0020] And / or, when the one-dimensional coupling grating includes a tilted grating, the tilt angle of the tilted grating is 0~60°; preferably 30~45°;

[0021] And / or, when the one-dimensional coupled grating includes a blazed grating, the blazed angle of the blazed grating is 0~90°; preferably 45~60°.

[0022] Furthermore, the output diffraction optical element is configured as a two-dimensional coupling grating; wherein,

[0023] The height of the two-dimensional coupling grating is 10~500nm; preferably 60~100nm;

[0024] And / or, the duty cycle of the two-dimensional coupling grating is 20~100%; preferably 50~80%;

[0025] And / or, the period of the two-dimensional coupling grating is 150~500nm; preferably 300~350nm;

[0026] And / or, when the two-dimensional coupling grating includes a tilted grating, the tilt angle of the tilted grating is 0~60°; preferably 30~45°;

[0027] And / or, when the two-dimensional coupled grating includes a blazed grating, the blazed angle of the blazed grating is 0~90°; preferably 45~60°.

[0028] Alternatively, the output diffraction optical element can be configured as a one-dimensional folding grating and a one-dimensional coupling grating; wherein,

[0029] The height of the one-dimensional folding grating is 10~500nm; preferably 40~100nm;

[0030] And / or, the duty cycle of the one-dimensional folding grating is 20-100%; preferably 30-50%;

[0031] And / or, the period of the one-dimensional folding grating is 150~500nm; preferably 280~330nm;

[0032] And / or, when the one-dimensional folding grating includes a tilted grating, the tilt angle of the tilted grating is 0~60°; preferably 10~30°;

[0033] And / or, when the one-dimensional folding grating includes a blazed grating, the blazed angle of the blazed grating is 0~90°; preferably 60~80°.

[0034] The height of the one-dimensional coupling grating is 10~500nm; preferably 180~230nm.

[0035] And / or, the duty cycle of the one-dimensional coupling grating is 20~100%; preferably 50~70%;

[0036] And / or, the period of the one-dimensional coupling grating is 150~500nm; preferably 280~330nm;

[0037] And / or, when the one-dimensional coupling grating includes a tilted grating, the tilt angle of the tilted grating is 0~60°; preferably 10~30°.

[0038] And / or, when the one-dimensional coupled grating includes a blazed grating, the blazed angle of the blazed grating is 0~90°; preferably 75~90°.

[0039] Furthermore, the low-fold filling layer is disposed on at least one side surface of the waveguide substrate;

[0040] And / or, the low-refractive-index filler layer is a composite layer (preferably 1 to 4 layers) of one or more of SiO2, MgF2, perfluoroalkene, optical resin and polycarbonate.

[0041] And / or, the refractive index of the low-refractive-index filling layer does not exceed 1.5;

[0042] And / or, the thickness of the low-fold filling layer is 0.1~20μm.

[0043] Furthermore, the period (100~150nm) of the subwavelength diffraction microstructure is smaller than the period (150~500nm) of the output diffraction optical element.

[0044] Furthermore, the subwavelength diffraction microstructure is one or a combination of several of the following: straight grating, blazed grating, tilted grating, double-ridge grating, and one-dimensional multilayer grating;

[0045] And / or, the subwavelength diffraction microstructure is one or a combination of several of optical glass, optical resin, Si3N4, TiO2 and SiC;

[0046] And / or, the refractive index of the subwavelength diffraction microstructure exceeds 1.7;

[0047] And / or, the height of the subwavelength diffraction microstructure is 10~500 nm;

[0048] And / or, the duty cycle of the subwavelength diffraction microstructure is 20-100%;

[0049] And / or, the period of the subwavelength diffraction microstructure is 150~500nm;

[0050] And / or, when the one-dimensional coupling grating includes a tilted grating, the tilt angle of the tilted grating is 0~60°;

[0051] And / or, when the one-dimensional coupled grating includes a blazed grating, the blazed angle of the blazed grating is 0~90°.

[0052] Furthermore, the diffractive optical thin film is composed of several low-refractive-index film layers and high-refractive-index film layers stacked alternately;

[0053] And / or, the low refractive index film is a composite film of one or more of MgF2, SiO2, Si3N4, Al2O3 and HfO3;

[0054] And / or, the high refractive index film is a composite film of one or more of TiO2, Si, Ta2O5 and SiC;

[0055] And / or, the thickness of the diffractive optical film is 0.1~20μm.

[0056] Furthermore, the refractive indices of the waveguide substrate and the low-refractive-index filling layer satisfy the following condition:

[0057] ;

[0058] ;

[0059] ;

[0060] ;

[0061] ;

[0062] ;

[0063] ;

[0064] ;

[0065] ;

[0066] Wherein, n0, n1, n2, and n3 are the refractive indices of the beam incident environment, waveguide substrate, output diffractive optical element, and low-refractive filling layer, respectively; d1 and d2 are the periods of the input and output diffractive optical elements (one-dimensional folding gratings), respectively; β1 and β2 are the grating vector directions of the input and output diffractive optical elements (one-dimensional folding gratings), respectively; θ is the polar angle of the incident beam; φ is the azimuth angle of the incident beam; and DIFF_1 and DIFF_2 are the diffraction angles of the beam after passing through the input and output diffractive optical elements (one-dimensional folding gratings), respectively.

[0067] In summary, the beneficial technical effects of the present invention are as follows:

[0068] 1. This invention is based on a conventional diffractive waveguide architecture, and adds a low-refractive-index filling layer, as well as a subwavelength diffractive microstructure and / or a diffractive optical thin film architecture. This not only replaces the air cover layer that protects the grating in AR lenses, reducing the size of the lens, but also further improves the transmittance of the input and output diffractive optical element regions. The diffraction efficiency in the visible light region reaches more than 70-90%, and the overall diffraction efficiency is improved by about 3-10%. Without affecting the optical performance, it solves the problems of waveguide volume, weak rainbow patterns, light leakage, and transmittance.

[0069] 2. The thicknesses of the waveguide substrate, cover lens, and air gap in existing lenses are typically 0.5~1.0mm, 50~100μm, and 50~100μm, respectively. The total thickness of such lenses is also controlled at around 0.65~1.30mm. In contrast, the thickest structure design of this invention, which adopts the structure of "diffractive waveguide architecture - low-fold filling layer - subwavelength diffractive microstructure - diffractive optical thin film architecture", has a thickness of only 0.50~1.04mm, a thickness reduction of up to 0.15~0.26mm. This optimization makes the lens product thinner and more compact.

[0070] 3. Without subwavelength diffraction microstructures and diffraction optical films, ambient light will propagate along the dotted path, inevitably causing the wearer to observe rainbow patterns, severely impacting the visual experience. However, with subwavelength diffraction microstructures and / or diffraction optical films, ambient light will propagate along the actual path. Furthermore, when the periods of the input and output diffraction optical elements are controlled within the range of 250-400 nm, and the period of the subwavelength diffraction microstructure is within the range of 100-150 nm, the propagation path of ambient light changes significantly. Due to the extremely small period of the subwavelength diffraction microstructure, even ambient light incident from the edge will be diffracted into large angles and projected onto the grating surface. After the diffraction of the grating and the refraction process of the waveguide, these rays will deviate from the direction of the human eye, effectively eliminating the rainbow pattern phenomenon and significantly improving the wearer's visual comfort.

[0071] 4. Without subwavelength diffraction microstructures and diffraction optical films, the transmitted first-order light generated by waveguide substrate diffraction will propagate along the dotted path, easily entering the human eye and posing a risk of information leakage. However, this problem is effectively solved when subwavelength diffraction microstructures and diffraction optical films are incorporated. When the periods of the input and output diffraction optical elements are controlled within the range of 250–400 nm, and the period of the subwavelength diffraction microstructure is between 100 and 150 nm, the propagation path of the transmitted order light changes significantly, propagating along the realized path. When the period of the subwavelength diffraction microstructure is significantly reduced, at the same incident angle, the diffraction angle of the outgoing light is large after modulation by the microstructure, causing the outgoing direction to deviate significantly from the human eye's viewing angle. In this way, the structure can effectively block the light leakage path, significantly improving system confidentiality and security, and achieving efficient suppression of light leakage. Attached Figure Description

[0072] Figure 1 This is a schematic diagram of ambient light diffraction of the reflective AR diffraction waveguide lens of Embodiment 1 and Comparative Example 1 of the present invention.

[0073] Figure 2 This is a schematic diagram of image beam diffraction of the reflective AR diffraction waveguide lens of Embodiment 1 and Comparative Example 1 of the present invention.

[0074] Figure 3 This is a schematic diagram of the structure of the reflective AR diffractive waveguide lens of Embodiment 2 of the present invention.

[0075] Figure 4 This is a schematic diagram showing the connection relationship between the waveguide substrate, the input diffractive optical element, and the output diffractive optical element in Embodiment 2 of the present invention.

[0076] Figure 5 This is a schematic diagram of the structure of the reflective AR diffractive waveguide lens of Embodiment 7 of the present invention.

[0077] Figure 6 This is a schematic diagram of the structure of the reflective AR diffractive waveguide lens of Embodiment 11 of the present invention.

[0078] Figure 7 This is a schematic diagram showing the connection relationship between the waveguide substrate, the input diffractive optical element, and the output diffractive optical element in Embodiment 14 of the present invention.

[0079] Figure 8 These are the lens diffraction efficiency diagrams of embodiments 2-6 of the present invention.

[0080] Figure 9 These are the lens diffraction efficiency diagrams of Embodiments 7-8 and Comparative Example 1 of the present invention.

[0081] In the figure, 1 is the waveguide substrate; 2 is the input diffractive optical element; 21 is the one-dimensional coupling grating; 3 is the output diffractive optical element; 31 is the one-dimensional folding grating; 32 is the one-dimensional coupling grating; 33 is the two-dimensional coupling grating; 4 is the low-refractive filling layer; 5 is the subwavelength diffractive microstructure; and 6 is the diffractive optical thin film. Detailed Implementation

[0082] To make the technical means, creative features, objectives and effects of this invention clearer and easier to understand, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0083] Example

[0084] Example 1: Refer to Figure 1 and Figure 2 This invention discloses a reflective AR diffractive waveguide lens, comprising a waveguide substrate 1, an input diffractive optical element 2, an output diffractive optical element 3, a low-refractive-index filling layer 4, a subwavelength diffractive microstructure 5, and a diffractive optical thin film 6. The input diffractive optical element 2 couples a light beam into the waveguide substrate 1. After total internal reflection within the waveguide substrate 1, the coupled light beam is gradually coupled out by the output diffractive optical element 3. The low-refractive-index filling layer 4 is embedded in the grating gap between the input diffractive optical element 2 and the output diffractive optical element 3, and its height exceeds that of the input diffractive optical element 2 and the output diffractive optical element 3. The subwavelength diffractive microstructure 5 and the diffractive optical thin film 6 are arranged on the low-refractive-index filling layer 4 and are positioned relative to the output diffractive optical element 3.

[0085] Example 2: Refer to Figure 3 and Figure 4 This invention discloses a reflective AR diffractive waveguide lens, which differs from Embodiment 1 in that it includes a subwavelength diffractive microstructure 5 and does not include a diffractive optical thin film 6.

[0086] First, the waveguide substrate 1 is optical glass with a refractive index of 2.0 and a thickness of 1.0 mm.

[0087] Secondly, the input diffractive optical element 2 and the output diffractive optical element 3 are straight gratings that are closely attached to the surface of the waveguide substrate 1 and are made of TiO2 with a refractive index of 2.4.

[0088] The input diffraction optical element 2 is configured as a one-dimensional coupling grating 21, which is tightly bonded to the surface of the waveguide substrate 1.

[0089] The one-dimensional coupling grating 32 has a height of 40 nm, a period of 300 nm, and a duty cycle of 50%.

[0090] The output diffraction optical element 3 is configured as a one-dimensional bend grating 31 and a one-dimensional coupling grating 32, which are tightly bonded to the surface of the waveguide substrate 1.

[0091] The one-dimensional lattice grating 31 has a height of 100 nm, a period of 300 nm, and a duty cycle of 42%.

[0092] The one-dimensional coupling grating 32 has a height of 205 nm, a period of 300 nm, and a duty cycle of 68%.

[0093] Furthermore, a low-refractive-index filling layer 4 is disposed on one side surface of the waveguide substrate 1, and is made of optical resin with a refractive index of 1.45 and has a thickness of 15 μm.

[0094] Finally, the subwavelength diffraction microstructure 5 is a straight grating, made of TiO2 with a refractive index of 2.4, with a height of 80 nm, a period of 110 nm, and a duty cycle of 40%.

[0095] Examples 3-6: These are reflective AR diffractive waveguide lenses disclosed in this invention. The difference from Example 2 is that the low-refractive filling layer 4 is disposed on one side surface of the waveguide substrate 1, and is made of optical resin with a refractive index of 1.45, with thicknesses of 1, 3, 5, and 7 μm, respectively.

[0096] Example 7: Refer to Figure 5 This invention discloses a reflective AR diffractive waveguide lens, which differs from Embodiment 2 in that it does not include the subwavelength diffractive microstructure 5, but includes a diffractive optical thin film 6.

[0097] The input diffractive optical element 2 and the output diffractive optical element 3 are made of SiC with a refractive index of 2.7.

[0098] The diffractive optical thin film 6 is composed of two layers of low refractive index film (HfO3 film) and two layers of high refractive index film (TiO2 film) stacked alternately. Along the thickness direction of the waveguide substrate 1, from bottom to top, the layers are 0.05 μm HfO3 film, 0.10 μm TiO2 film, 0.07 μm HfO3 film, and 0.16 μm TiO2 film. The total thickness of the diffractive optical thin film 6 is 0.38 μm.

[0099] Example 8: This is a reflective AR diffractive waveguide lens disclosed in this invention. The difference between it and Examples 2 and 7 is that it includes a subwavelength diffractive microstructure 5 and a diffractive optical film 6. The diffractive optical film 6 is embedded in the grating gap of the subwavelength diffractive microstructure 5 and completely covers the surface of the subwavelength diffractive microstructure 5.

[0100] The input diffractive optical element 2, the output diffractive optical element 3, and the subwavelength diffractive microstructure 5 are made of SiC with a refractive index of 2.7.

[0101] Example 9: This is a reflective AR diffractive waveguide lens disclosed in this invention. The difference from Example 2 is that the low-reflection filling layer 4 is disposed on both sides of the waveguide substrate 1.

[0102] Example 10: This is a reflective AR diffractive waveguide lens disclosed in this invention. The difference from Example 7 is that the low-reflection filling layer 4 is disposed on both sides of the waveguide substrate 1.

[0103] Example 11: Refer to Figure 6 This invention discloses a reflective AR diffractive waveguide lens, which differs from Embodiment 8 in that the low-reflection filling layer 4 is disposed on both sides of the waveguide substrate 1.

[0104] Example 12: This is a reflective AR diffractive waveguide lens disclosed in this invention. The difference from Example 2 is that the input diffractive optical element 2 and the output diffractive optical element 3 are tilted gratings. Wherein,

[0105] The one-dimensional coupling grating 21 has a height of 40nm, a period of 300nm, a duty cycle of 50%, and a tilt angle of 40°.

[0106] The one-dimensional folding grating 31 has a height of 100nm, a period of 300nm, a duty cycle of 42%, and a tilt angle of 10°.

[0107] The one-dimensional coupling grating 21 has a height of 205 nm, a period of 300 nm, a duty cycle of 68%, and a tilt angle of 25°.

[0108] Example 13: This is a reflective AR diffractive waveguide lens disclosed in this invention. The difference from Example 2 is that the input diffractive optical element 2 and the output diffractive optical element 3 are blazed gratings. Wherein,

[0109] The one-dimensional coupling grating 21 has a height of 40 nm, a period of 300 nm, a duty cycle of 50%, and a blaze angle of 55°.

[0110] The one-dimensional lattice 31 has a height of 40nm, a period of 300nm, a duty cycle of 42%, and a blaze angle of 70°.

[0111] The one-dimensional coupling grating 21 has a height of 205 nm, a period of 300 nm, a duty cycle of 68%, and a blaze angle of 90°.

[0112] Example 14: Refer to Figure 7This invention discloses a reflective AR diffractive waveguide lens, which differs from Embodiment 2 in that the output diffractive optical element 3 is configured as a two-dimensional coupling grating 33, which is embedded within the material of the cutoff layer.

[0113] The two-dimensional coupling grating 33 has a height of 80 nm, a period of 320 nm, and a duty cycle of 61%.

[0114] Comparative Example

[0115] Comparative Example 1: Reference Figure 1 and Figure 2 This invention discloses a reflective AR diffractive waveguide lens, which differs from Embodiment 7 in that it does not include the subwavelength diffractive microstructure 5 and the diffractive optical thin film 6.

[0116] Performance testing

[0117] Experimental Example 1: By simulating the ambient beam transmission path in the lenses of Example 1 and Comparative Example 1, referring to... Figure 1 Without the subwavelength diffraction microstructure 5 and the diffraction optical film 6, ambient light propagates along the dotted path, inevitably causing the wearer to observe rainbow patterns and severely impacting their visual experience. However, with the subwavelength diffraction microstructure 5 and / or the diffraction optical film 6, ambient light propagates along the actual path. Furthermore, when the periods of the input and output diffraction optical elements 3 are controlled within the range of 250–400 nm, and the period of the subwavelength diffraction microstructure 5 is between 100 and 150 nm, the propagation path of ambient light changes significantly. Due to the extremely small period of the subwavelength diffraction microstructure 5, even ambient light incident from the edge is diffracted at a large angle and projected onto the grating surface. After diffraction by the grating and refraction by the waveguide, these rays deviate from the direction of the human eye, effectively eliminating the rainbow pattern and significantly improving the wearer's visual comfort.

[0118] By simulating the image beam transmission path in the lens of Example 1 and Comparative Example 1, referring to Figure 2Without the subwavelength diffraction microstructure 5 and the diffraction optical film 6, the transmitted first-order light generated by the waveguide substrate 1 will propagate along the dotted path, easily entering the human eye and posing a risk of information leakage. However, this problem is effectively solved when the subwavelength diffraction microstructure 5 and the diffraction optical film 6 are included. When the periods of the input and output diffraction optical elements 3 are controlled within the range of 250-400 nm, and the period of the subwavelength diffraction microstructure 5 is within the range of 100-150 nm, the propagation path of the transmitted order light changes significantly, propagating along the realized path. When the period of the subwavelength diffraction microstructure 5 is significantly reduced, at the same incident angle, the diffraction angle of the outgoing light is large after modulation by the microstructure, causing the outgoing direction to deviate significantly from the human eye's viewing angle. In this way, the structure can effectively block the light leakage path, significantly improving the system's confidentiality and security, and achieving efficient suppression of light leakage.

[0119] Experimental Example 2: The diffraction efficiency of the lenses in Examples 2-6 was tested, and the results are as follows: Figure 8 As shown.

[0120] from Figure 8 It can be seen that the thickness of the low-refractive index filling layer 4 has a negligible effect on the diffraction efficiency of the lens. However, the refractive indices of the waveguide substrate 1 and the low-refractive index filling layer 4 satisfy the following condition to ensure that the coupled beam undergoes total internal reflection in the waveguide substrate 1.

[0121] ;

[0122] ;

[0123] ;

[0124] ;

[0125] ;

[0126] ;

[0127] ;

[0128] ;

[0129] ;

[0130] Wherein, n0, n1, n2, and n3 are the refractive indices of the beam incident environment, waveguide substrate 1, output diffractive optical element 3, and low-refractive filling layer 4, respectively; d1 and d2 are the periods of the input diffractive optical element 2 and the output diffractive optical element 3 (one-dimensional folding grating 31), respectively; β1 and β2 are the grating vector directions of the input diffractive optical element 2 and the output diffractive optical element 3 (one-dimensional folding grating 31), respectively; θ is the polar angle of the incident beam; φ is the azimuth angle of the incident beam; and DIFF_1 and DIFF_2 are the beam diffraction angles after passing through the input diffractive optical element 2 and the output diffractive optical element 3 (one-dimensional folding grating 31), respectively.

[0131] Experimental Example 3: The diffraction efficiency of the lenses in Examples 7-8 and Comparative Example 1 was tested, and the results are as follows: Figure 9 As shown.

[0132] from Figure 9 It can be seen that, compared with a grating waveguide consisting only of waveguide substrate 1, input diffractive optical element 2, and output diffractive optical element 3, by adding a low-reflection filling layer 4 (spacer layer), and subwavelength diffractive microstructure 5 (microstructure) / subwavelength diffractive microstructure 5 and diffractive optical thin film 6 (microstructure + film layer), the transmittance of the input diffractive optical element 2 and output diffractive optical element 3 regions can be further improved, the diffraction efficiency in the visible light region can reach more than 70-90%, and the overall diffraction efficiency can be improved by about 3-10%.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A reflective AR diffractive waveguide lens, characterized in that: The device includes a waveguide substrate (1), an input diffractive optical element (2), an output diffractive optical element (3), a low-refractive-index filling layer (4), and a subwavelength diffractive microstructure (5) and / or a diffractive optical film (6). The input diffractive optical element (2) couples a light beam into the waveguide substrate (1). After total reflection in the waveguide substrate (1), the coupled light beam is coupled out stepwise by the output diffractive optical element (3). The low-refractive-index filling layer (4) is embedded in the grating gap between the input diffractive optical element (2) and the output diffractive optical element (3) and its height exceeds that of the input diffractive optical element (2) and the output diffractive optical element (3). The subwavelength diffractive microstructure (5) and / or the diffractive optical film (6) are arranged on the low-refractive-index filling layer (4) and are arranged relative to the output diffractive optical element (3).

2. The reflective AR diffractive waveguide lens according to claim 1, characterized in that: The input diffractive optical element (2) and the output diffractive optical element (3) are one or more of the following: straight grating, blazed grating, tilted grating, double-ridge grating and one-dimensional multilayer grating; And / or, the input diffractive optical element (2) and the output diffractive optical element (3) are respectively closely attached to the surface of the waveguide substrate (1) or embedded in the material of the waveguide substrate (1); And / or, the input diffractive optical element (2) and the output diffractive optical element (3) are one or more of optical glass, optical resin, Si3N4, TiO2 and SiC; And / or, the refractive index of the input diffractive optical element (2) exceeds 1.7, and the refractive index n1 of the output diffractive optical element (3) exceeds 1.

7.

3. The reflective AR diffractive waveguide lens according to claim 2, characterized in that: The input diffraction optical element (2) is configured as a one-dimensional coupling grating (21); wherein, The height of the one-dimensional coupling grating (21) is 10~500nm; And / or, the duty cycle of the one-dimensional coupling grating (21) is 20~100%; And / or, the period of the one-dimensional coupling grating (21) is 150~500nm; And / or, when the one-dimensional coupling grating (21) includes a tilt grating, the tilt angle of the tilt grating is 0~60°; And / or, when the one-dimensional coupled grating (21) includes a blazed grating, the blazed angle of the blazed grating is 0~90°.

4. A reflective AR diffractive waveguide lens according to claim 2, characterized in that: The output diffraction optical element (3) is configured as a two-dimensional coupling grating (33); wherein, The height of the two-dimensional coupling grating (33) is 10~500nm; And / or, the duty cycle of the two-dimensional coupling grating is 20~100%; And / or, the period of the two-dimensional coupling grating is 150~500nm; And / or, when the two-dimensional coupled grating includes a tilted grating, the tilt angle of the tilted grating is 0~60°; And / or, when the two-dimensional coupled grating includes a blazed grating, the blazed angle of the blazed grating is 0~90°.

5. A reflective AR diffractive waveguide lens according to claim 2, characterized in that: The output diffraction optical element (3) is configured as a one-dimensional folding grating (31) and a one-dimensional coupling grating (32); wherein, The height of the one-dimensional folding grating (31) is 10~500nm; And / or, the duty cycle of the one-dimensional folding grating (31) is 20~100%; And / or, the period of the one-dimensional folding grating (31) is 150~500nm; And / or, when the one-dimensional folding grating (31) includes a tilt grating, the tilt angle of the tilt grating is 0~60°; And / or, when the one-dimensional folding grating (31) includes a blazing grating, the blazing angle of the blazing grating is 0~90°; The height of the one-dimensional coupling grating (32) is 10~500nm; And / or, the duty cycle of the one-dimensional coupling grating (32) is 20~100%; And / or, the period of the one-dimensional coupling grating (32) is 150~500nm; And / or, when the one-dimensional coupling grating (32) includes a tilt grating, the tilt angle of the tilt grating is 0~60°; And / or, when the one-dimensional coupled grating (32) includes a blazed grating, the blazed angle of the blazed grating is 0~90°.

6. A reflective AR diffractive waveguide lens according to claim 5, characterized in that: The low-fold filling layer (4) is disposed on at least one side surface of the waveguide substrate (1); And / or, the low-fold filler layer (4) is a composite layer of one or more of SiO2, MgF2, polyfluoroalkylene, optical resin and polycarbonate; And / or, the refractive index of the low-refractive-index filling layer (4) does not exceed 1.5; And / or, the thickness of the low-fold filling layer (4) is 0.1~20μm.

7. A reflective AR diffractive waveguide lens according to claim 5, characterized in that: The period of the subwavelength diffraction microstructure (5) is smaller than the period of the output diffraction optical element (3).

8. A reflective AR diffractive waveguide lens according to claim 7, characterized in that: The subwavelength diffraction microstructure (5) is a combination of one or more of the following: straight grating, blazed grating, tilted grating, double-ridge grating, and one-dimensional multilayer grating; And / or, the subwavelength diffraction microstructure (5) is one or a combination of several of optical glass, optical resin, Si3N4, TiO2 and SiC; And / or, the refractive index of the subwavelength diffraction microstructure (5) exceeds 1.7; And / or, the height of the subwavelength diffraction microstructure (5) is 10~500 nm; And / or, the duty cycle of the subwavelength diffraction microstructure (5) is 20~100%; And / or, the period of the subwavelength diffraction microstructure (5) is 150~500nm; And / or, when the subwavelength diffraction microstructure (5) includes a tilted grating, the tilt angle of the tilted grating is 0~60°; And / or, when the subwavelength diffraction microstructure (5) includes a blazed grating, the blazed angle of the blazed grating is 0~90°.

9. A reflective AR diffractive waveguide lens according to claim 5, characterized in that: The diffractive optical thin film (6) is composed of several low-refractive-index film layers and high-refractive-index film layers stacked alternately; And / or, the low refractive index film is a composite film of one or more of MgF2, SiO2, Si3N4, Al2O3 and HfO3; And / or, the high refractive index film is a composite film of one or more of TiO2, Si, Ta2O5 and SiC; And / or, the thickness of the diffractive optical thin film (6) is 0.1~20μm.

10. A reflective AR diffractive waveguide lens according to claim 5, characterized in that: The refractive indices of the waveguide substrate (1) and the low-refractive filling layer (4) satisfy the following condition: ； ； ； ； ； ； ； ； ； Wherein, n0, n1, n2, and n3 are the refractive indices of the beam incident environment, waveguide substrate (1), output diffractive optical element (3), and low-refractive filling layer (4), respectively; d1 and d2 are the periods of the input diffractive optical element (2) and the output diffractive optical element (3), respectively; β1 and β2 are the grating vector directions of the input diffractive optical element (2) and the output diffractive optical element (3), respectively; θ is the polar angle of the incident beam; φ is the azimuth angle of the incident beam; and DIFF_1 and DIFF_2 are the diffraction angles of the beam after passing through the input diffractive optical element (2) and the output diffractive optical element (3), respectively.

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