Lens unit and AR device comprising the same

Abstract

A lens unit, comprising a substrate (1) made of optical waveguide material, having a first optical plane and a second optical plane opposite to the first optical plane, and a first diffraction grating region (2) and a second diffraction grating region (3), wherein the diffraction grating region provided on the first optical plane of the substrate (1) constitutes the first diffraction grating region (2), and the diffraction grating region provided on the second optical plane opposite to the first optical plane of the substrate (1) constitutes the second diffraction grating region (3), wherein the first diffraction grating region (2) has a consistent first grating vector on the first optical plane of the substrate (1), and the second diffraction grating region (3) has a consistent second grating vector on the second optical plane opposite to the first optical plane of the substrate (1). An AR glasses comprising the lens unit, which improves the image quality input to the human eye, and has a simpler manufacturing process and lower cost compared with the traditional waveguide lens unit.

Description

Technical Field

[0001] This invention relates to a lens unit and an AR device including the lens unit. Background Technology

[0002] The description herein provides only background information in relation to the present invention and does not necessarily constitute prior art.

[0003] Augmented Reality (AR) technology is a new technology that seamlessly integrates real-world information with virtual-world information. It uses computer technology to simulate and overlay physical information that is difficult to experience in a specific time and space in the real world, thus providing people with a sensory experience that transcends reality. Because of its characteristic of overlaying virtual objects or images onto a real environment, AR technology has shown enormous application potential in numerous fields.

[0004] Optical waveguide lenses (lens units) are key components in next-generation augmented reality (AR) technology. They combine the principles of total internal reflection waveguides and diffraction elements to replicate and expand the exit pupil in an imaging system, offering advantages such as a large field of view, small size, and light weight. While transmitting image light laterally, optical waveguide lenses do not obstruct the viewer's vertical observation of the real-world scene; therefore, waveguide lenses have become an inevitable trend in the development of AR technology.

[0005] A typical optical waveguide technology involves projecting an image light source emitted from a microdisplay through a projection lens into the incident grating region of a waveguide sheet. Through total internal reflection transmission via the waveguide sheet and the effect of the diffraction grating, the incident light source is replicated and expanded in two directions, creating an extended exit pupil in the coupling grating region, thus increasing the field of view for the human eye. Currently, the most commonly used and representative diffractive optical elements are two-dimensional cross gratings and butterfly gratings, used for coupling the signal light source onto the waveguide sheet. A cross grating is a grating with periodicity in two dimensions, while a butterfly grating has transition grating regions on both sides of the incident grating. Cross gratings are more difficult to fabricate, and their design freedom is also lower than that of butterfly gratings (groove depth, tilt, fill factor, etc.). Butterfly gratings, due to their four diffraction grating regions, have higher tolerance requirements in fabrication, making their fabrication equally difficult.

[0006] In the optical design of waveguides, it is often required that the incident rays in the coupling and turning regions and the outgoing rays in the coupling and exiting regions remain parallel to transmit the image to the human eye completely and without distortion. This requires that the sum of the grating vectors in the coupling, turning, and exiting regions of the waveguide be zero, meaning that the sum of the grating vectors of the light passing through multiple diffraction gratings is zero. This places extremely high demands on the design and fabrication precision of the grating structure. On the one hand, the grating structure design must have high diffraction efficiency; on the other hand, there will inevitably be errors in grating fabrication, such as the direction, angle, and depth of the grating lines not perfectly matching the design, resulting in certain errors. Consequently, the sum of all relevant grating vectors in the actual manufactured waveguide may not be zero, and the incident and outgoing rays of the waveguide may not remain parallel, ultimately leading to aberrations and distortion in the image input to the human eye.

[0007] Conventional waveguide sheets employ three or more grating structures, including an input grating, a deflection grating, and an output grating. The vector sum of the three gratings must be zero to ensure that the input and output rays are parallel. However, there are always manufacturing tolerances in actual grating manufacturing, making it impossible to guarantee that the three grating structures manufactured will perfectly match the design values. Summary of the Invention

[0008] The purpose of this invention is to propose a lens unit and AR device that can improve the image quality input to the human eye. In particular, it can overcome the defects of the prior art, and can simply and effectively keep the outgoing light rays and the incoming light rays completely parallel. While achieving the integration of coupling in, pupil expansion and coupling out, it is simpler to manufacture and cheaper than traditional waveguide lens units.

[0009] Therefore, according to a first aspect of the present invention, a lens unit is provided, comprising: a substrate made of an optical waveguide material having a first optical plane and a second optical plane opposite to the first optical plane; and

[0010] A first diffraction grating region and a second diffraction grating region, wherein the diffraction grating region disposed on the first optical plane of the substrate constitutes the first diffraction grating region, and the diffraction grating region disposed on the second optical plane of the substrate opposite to the first optical plane constitutes the second diffraction grating region.

[0011] The first diffraction grating region has a consistent first grating vector on the first optical plane of the substrate, and the second diffraction grating region has a consistent second grating vector on the second optical plane of the substrate opposite to the first optical plane.

[0012] According to the technical solution of the present invention, the light emitted by the micro-projector is diffracted and coupled into the substrate by two diffraction grating surfaces, and then diffused and transmitted through multiple total internal reflections and diffractions, ultimately allowing the image to be seen in any area of ​​the working part of the grating. Because the lens unit of the present invention has only two grating vectors—namely, the first diffraction grating region has a consistent first grating vector on the first optical plane of the substrate, and the second diffraction grating region has a consistent second grating vector on the second optical plane of the substrate opposite to the first optical plane—it offers high design freedom, a simple structure, and is easy to mass-produce, thus possessing high industrial application value.

[0013] According to some embodiments of the first aspect of the present invention, a first diffraction grating region on a first optical plane of the substrate is a continuous region, and / or a second diffraction grating region on a second optical plane of the substrate opposite to the first optical plane is a continuous region.

[0014] According to some embodiments of the first aspect of the invention, the first diffraction grating region is continuous over the entire first optical plane of the substrate, and / or the second diffraction grating region is continuous over the entire second optical plane of the substrate.

[0015] According to some embodiments of the first aspect of the present invention, a first diffraction grating region on a first optical plane of the substrate is a discontinuous region, and / or a second diffraction grating region on a second optical plane of the substrate opposite to the first optical plane is a discontinuous region.

[0016] According to some embodiments of the first aspect of the present invention, the first grating vector of the first diffraction grating region is different from the second grating vector of the second diffraction grating region.

[0017] According to the present invention, light can be modulated by at least four gratings on the upper and lower surfaces, and the output light can maintain the same direction as the input light, thereby improving the image quality input to the human eye. According to some embodiments of the first aspect of the present invention, the incident light is coupled out after being modulated by four gratings within the lens unit.

[0018] According to some embodiments of the first aspect of the present invention, a first diffraction grating region disposed on a first optical plane of the substrate and a second diffraction grating region disposed on a second optical plane of the substrate opposite to the first optical plane modulate the incident light twice, respectively.

[0019] According to some embodiments of the first aspect of the present invention, a first diffraction grating region disposed on a first optical plane of the substrate and a second diffraction grating region disposed on a second optical plane of the substrate opposite to the first optical plane have the same grating period.

[0020] According to some embodiments of the first aspect of the present invention, in the plane where the lens unit is located, the grating groove lines of the first diffraction grating region and the grating groove lines of the second diffraction grating region have an angle of 40 to 90°.

[0021] According to some embodiments of the first aspect of the present invention, the grating groove lines of the first diffraction grating region and the grating groove lines of the second diffraction grating region have an angle of 60°.

[0022] According to some embodiments of the first aspect of the present invention, during the diffraction propagation of the lens unit, the diffraction angle of the diffracted light satisfies the formula:

[0023]

[0024] In the formula | k r | represents the amplitude of the target light wave vector, n is the refractive index of the optical waveguide material, λ0 is the center wavelength of the image light source, and θ max Indicates the maximum transmission angle.

[0025] According to some embodiments of the first aspect of the present invention, the optical waveguide material constituting the substrate is optical glass or optical resin.

[0026] According to some embodiments of the first aspect of the present invention, a first diffraction grating region disposed on a first optical plane of the substrate and a second diffraction grating region disposed on a second optical plane of the substrate opposite to the first optical plane include a surface relief grating.

[0027] According to some embodiments of the first aspect of the present invention, a first diffraction grating region disposed on a first optical plane of the substrate and a second diffraction grating region disposed on a second optical plane of the substrate opposite to the first optical plane include a positive grating, a blazed grating, a tilted grating and / or a sinusoidal grating.

[0028] According to some embodiments of the first aspect of the present invention, a first diffraction grating region disposed on a first optical plane of the substrate and a second diffraction grating region disposed on a second optical plane of the substrate opposite to the first optical plane at least partially overlap each other on both sides of the substrate.

[0029] According to some embodiments of the first aspect of the present invention, in the plane where the lens unit is located, the grating vector of the first diffraction grating region and the grating vector of the second diffraction grating region are axially symmetric.

[0030] According to some embodiments of the first aspect of the present invention, a first diffraction grating region disposed on a first optical plane of the substrate and a second diffraction grating region disposed on a second optical plane of the substrate opposite to the first optical plane have the same groove line structure.

[0031] According to some embodiments of the first aspect of the present invention, the lens unit is a light-transmitting waveguide lens unit.

[0032] According to some embodiments of the first aspect of the invention, coupling and turning regions for incident light are provided on a first optical plane and / or a second optical plane of the substrate.

[0033] According to a second aspect of the invention, an AR device is provided, which includes at least one of the aforementioned lens units. In some embodiments of the second aspect of the invention, the AR device is AR glasses. Attached Figure Description

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. In the drawings, unless otherwise specified, the same reference numerals are used to denote the same parts. Wherein:

[0035] Figure 1 This is a schematic diagram of the structure of a lens unit according to some embodiments of the present invention, wherein the image light emitted by the micro-projector is transmitted to the human eye through the lens unit;

[0036] Figure 2 This is a schematic diagram of the diffraction and transmission of incident light within a lens unit according to some embodiments of the present invention;

[0037] Figures 3(a)-(d) show the optical path diagrams at the grating interface at different diffraction transmission stages, respectively;

[0038] Figure 4 This is a three-dimensional schematic diagram of the diffraction transmission process in a waveguide sheet, taking fourth-order grating modulation as an example.

[0039] Figure 5 The grating vector k diagram of the diffraction propagation process within the waveguide sheet is shown;

[0040] Figure 6 This is a schematic diagram of the groove structure of the grating region according to some embodiments of the present invention;

[0041] Figures 7(a)-(d) are schematic diagrams of grating types according to some embodiments of the present invention;

[0042] Figure 8 This is a schematic diagram of the coupling-in and turning regions and the coupling-out region of a lens unit according to some embodiments of the present invention. Here, the coupling-in and turning regions are provided in one of the optical planes, and the coupling-in and turning regions are completely surrounded by the corresponding coupling-out regions.

[0043] Figure 9This is a schematic diagram of the coupling-in and turning regions and the coupling-out region of a lens unit according to some embodiments of the present invention. Here, a coupling-in and turning region are respectively provided in the first and second optical planes of the lens unit, and the coupling-in and turning regions are completely surrounded by the corresponding coupling-out regions.

[0044] Figure 10 This is a schematic diagram of the coupling-in and turning regions and the coupling-out region of a lens unit according to some embodiments of the present invention, wherein the coupling-in and turning regions are respectively connected to the corresponding coupling-out region portions.

[0045] Figure 11 This is a schematic diagram of the coupling-in and turning regions and the coupling-out regions of a lens unit according to some embodiments of the present invention, wherein the coupling-in and turning regions are not connected to the corresponding coupling-out regions.

[0046] Figure 12 This is a schematic diagram of AR glasses according to some embodiments of the present invention;

[0047] Figure 13 This is a schematic diagram of AR glasses according to some embodiments of the present invention, having a modified lens unit shape;

[0048] Figure 14 This is a schematic diagram of AR glasses according to some embodiments of the present invention, wherein a separate light guide element is provided;

[0049] Figure 15 This is a schematic diagram of AR glasses according to other embodiments of the present invention. Detailed Implementation

[0050] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the embodiments listed herein are merely for clearly illustrating the inventive concept of the present invention and should not be construed as limiting the present invention. The lens units and technical features of the AR devices involved herein, as long as they do not violate natural laws or technical specifications, can be arbitrarily combined or substituted within the framework of the present invention and are all within the scope of the present invention.

[0051] It should be noted that the embodiments shown in the accompanying drawings are merely examples used to specifically and vividly explain and illustrate the concept of the present invention. They are not necessarily drawn to scale in terms of size and structure, nor do they constitute a limitation on the concept of the present invention.

[0052] The terms "up," "down," "left," "right," "front," "back," "front," "back," "top," "bottom," "vertical," and "horizontal," mentioned or potentially used in this specification, are defined relative to the construction or normal use of the product as shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0053] The disclosed content provides a lens unit including a substrate made of optical waveguide material, having a first optical plane and a second optical plane opposite to the first optical plane. The lens unit further includes a first diffraction grating region and a second diffraction grating region, wherein the diffraction grating region disposed on the first optical plane of the substrate constitutes the first diffraction grating region, and the diffraction grating region disposed on the second optical plane of the substrate opposite to the first optical plane constitutes the second diffraction grating region. Here, the first diffraction grating region has a consistent first grating vector on the first optical plane of the substrate, and the second diffraction grating region has a consistent second grating vector on the second optical plane of the substrate opposite to the first optical plane.

[0054] In other words, according to the present invention, the diffraction grating regions on the first optical plane of the substrate all have the same grating vector, namely the first grating vector, while the diffraction grating regions on the second optical plane of the substrate opposite to the first optical plane all have the same grating vector, namely the second grating vector. Therefore, the lens unit (hereinafter also referred to as waveguide sheet) according to the present invention has a total of two grating vectors, which not only enables the outgoing and incoming rays to remain perfectly parallel in a simple and effective manner, but also allows for high design freedom, simple structure, and easy mass production, thus possessing high industrial application value.

[0055] Figure 1 This is a schematic diagram of the structure of a lens unit according to some embodiments of the present invention, wherein image light emitted by the microprojector 40 is transmitted to the human eye through the lens unit. Figure 1 As shown, the lens unit includes a substrate 1 made of an optical waveguide material, for example having a sheet-like or plate-like shape, and forming a total internal reflection diffractive optical waveguide. The substrate 1 has a first optical plane and a second optical plane opposite to the first optical plane. As an example, the optical waveguide material constituting the substrate 1 can be optical glass or optical resin.

[0056] A first diffraction grating region 2 and a second diffraction grating region 3 are respectively disposed on the substrate 1 made of optical waveguide material. The first diffraction grating region 2 is disposed on a first optical plane of the substrate 1, and the second diffraction grating region 3 is disposed on a second optical plane of the substrate 1 opposite to the first optical plane. With this arrangement, the first diffraction grating region 2 disposed on the first optical plane of the substrate 1 and the second diffraction grating region 3 disposed on the second optical plane of the substrate 1 opposite to the first optical plane are opposite to each other on both sides of the substrate 1, and preferably at least partially overlap. Thus, within the overlapping grating regions, light diffracts and propagates in the waveguide sheet between the two overlapping grating interfaces.

[0057] Furthermore, a first diffraction grating region 2, located on the first optical plane of the substrate 1, has a first grating vector, and a second diffraction grating region 3, located on the second optical plane of the substrate 1 opposite to the first optical plane, has a second grating vector. The incident light is coupled out after undergoing at least four grating modulations within the lens unit. Through this lens unit, or waveguide, a portion of the totally internally reflected light is diffracted and released into the eye each time it encounters the grating on the surface of the substrate 1, while the remaining portion continues to propagate in the waveguide until it hits the grating on the waveguide surface again.

[0058] In the illustrated embodiment, a diffraction grating working area is respectively provided on two opposing optical surfaces, namely the first diffraction grating region 2 and the second diffraction grating region 3. Thus, the image light emitted by the micro-projector 40 is coupled into the lens unit, and after undergoing multiple total internal reflections and diffractions in the substrate 1 of the lens unit, it diffuses, transmits, and is coupled out, and finally the image can be seen in both diffraction grating working areas.

[0059] Figure 2 This is a schematic diagram of the diffraction and transmission optical path of incident light within a lens unit according to some embodiments of the present invention. (Followed by...) Figure 2 The diagram illustrates the diffraction transmission path of incident light within a lens unit according to some embodiments of the present invention. Here, the image light rays are coupled into the lens unit at an angle to the waveguide surface, particularly substantially perpendicular to it. The plane containing one diffraction grating region is referred to as the upper surface, and the plane containing the other diffraction grating region is referred to as the lower surface. It should be noted that the assumed orientation relationships described here are merely for illustrative purposes in describing the diffraction transmission path; the principles and processes are equally applicable to other orientation relationships and are also within the scope of the present invention.

[0060] like Figure 2As shown, the image ray 'a' from the micro-projector 40 forms an angle with the waveguide surface, particularly being essentially perpendicular to it, and couples into the lens unit. For example, after the light shines from the upper surface onto the overlapping area of ​​the diffraction grating, it undergoes diffraction by the lower surface grating, producing diffraction orders in the direction of 'b'. Simultaneously, after diffraction by the upper surface grating, diffraction orders in the direction of 'c' are also produced. Due to the high symmetry in the subsequent transmission of the diffracted beams 'b' and 'c', the subsequent transmission will be explained using the 'b' diffracted beam as an example.

[0061] As shown in the figure, the diffraction order in direction b, after being diffracted by the upper surface grating, produces the diffraction order in direction d, while the zeroth-order diffracted light continues to propagate in direction b. The diffracted light in direction d, after being diffracted by the lower surface, produces the diffracted light in direction e, and the zeroth-order diffracted light continues to propagate in direction d. The diffraction order in direction e, after being diffracted by the upper surface, couples out a portion of the light ray f, and the zeroth-order diffracted light continues to propagate in direction e. A portion of ray f couples out towards the upper surface, its propagation direction symmetrical to the incident light ray a about the waveguide normal. The other portion of ray f couples out towards the lower surface, its propagation direction consistent with the incident light ray a.

[0062] Therefore, in some embodiments of the present invention, the incident light is coupled out of the waveguide after undergoing at least four grating modulations. During this propagation process, the angle between the propagation directions of the diffraction orders b, d, and e and the normal to the waveguide surface is greater than the critical angle required for total internal reflection, thereby ensuring lossless propagation inside the waveguide. During propagation, the zeroth-order diffracted light continues to propagate through total internal reflection, for example, diffracting in the three directions b, d, and e. This diffraction is accompanied by diffraction coupling out; for example, the zeroth-order diffracted light in the d direction is diffracted out again after two diffractions in the g and h directions. This diffusion continues until light can be coupled out throughout the entire working area of ​​the grating, allowing the human eye to observe a complete, continuous, and clear image at any position on the lens.

[0063] To clearly illustrate the light diffraction transmission process of the lens unit according to the present invention, Figures 3(a)-(d) show schematic diagrams of the optical path at the grating interface at different diffraction transmission stages.

[0064] Figures 3(a)-(b) illustrate schematic diagrams of the first diffraction occurring in the first and second diffraction grating regions of the image light, respectively. As shown in Figure 3(a), when the incident light I is incident orthogonally on the working region of the grating on the upper surface of the waveguide sheet, a transmission diffraction order T is generated in the waveguide sheet. -1 T0, T1, where T1 is the diffraction order in the c direction. In Figure 3(a), d represents the grating pitch, i.e., the distance between adjacent slots, h represents the slot depth, and W represents the bulge width.

[0065] Figure 3(b) shows the R generated when the transmission diffraction order T0 is incident on the working area of ​​the lower surface grating. -1 The three reflection diffraction orders are R0, R1, and R2.-1 This refers to the diffraction order in the direction of b.

[0066] Figure 3(c) shows a schematic diagram of the intermediate diffraction process in the waveguide sheet. In Figure 3(c), the upper region represents the dielectric waveguide layer, and the lower region represents air. The diffracted light in direction b is the incident light I in this figure, which is incident at a spherical angle (θ, φ) on the working area of ​​the diffraction grating on the upper surface, producing the reflected diffraction order R. -1 R0, where R -1 This refers to the diffraction order in the d-direction. The diffracted light in the d-direction is incident on the working region of the lower surface diffraction grating. This process can also be represented by Figure 3(c), where R... -1 The diffraction order is in the direction of e. For example, when the image rays are modulated four times at the grating interface, Figure 3(c) illustrates the second and third diffraction processes.

[0067] Figure 3(d) shows a schematic diagram of the image light rays coupled out of the waveguide sheet. For example, Figure 2 The e-direction diffraction order is incident on the working region of the upper surface diffraction grating, and this diffraction process can be represented by Figure 3(d). At this point, the transmission diffraction order T is generated. -1 With reflection diffraction order R -1 R0. For example, when the image light undergoes four modulations at the grating interface, Figure 3(d) illustrates the fourth diffraction process.

[0068] Taking fourth-order grating modulation as an example, Figure 4 A three-dimensional schematic diagram of the diffraction transmission process within a waveguide sheet is shown. As illustrated, image rays are coupled into the waveguide sheet along, for example, a z-axis substantially perpendicular to the grating plane. After the first diffraction (first grating modulation) through the grating regions on the upper and lower surfaces of the waveguide sheet, the rays continue to undergo second and third modulations within the waveguide sheet via diffraction and / or total internal reflection at the upper and lower grating interfaces. Finally, the rays are coupled out of the waveguide sheet via a fourth diffraction at the grating interfaces. Clearly, the incident rays in the coupling and transition regions, as well as the outgoing rays in the coupling regions, are symmetrical about the normal to the waveguide sheet surface, thus achieving complete and distortion-free transmission of the image to the human eye.

[0069] It should be noted that when the incident ray entering the waveguide and the outgoing ray exiting the waveguide are on the same side of the waveguide, the incident and outgoing rays are symmetrical about the normal to the waveguide surface. When the incident ray entering the waveguide and the outgoing ray exiting the waveguide are on opposite sides of the waveguide, the incident and outgoing rays maintain the same direction. Figure 4 In this embodiment, the incident ray a is perpendicular to the waveguide surface, and the incident ray a and the outgoing ray f are on the same side of the waveguide. It should be noted that... Figure 4In the process, since the incident ray a in the coupling and turning region is perpendicular to the waveguide surface, the outgoing ray f, which is symmetrical to the incident ray a with respect to the normal of the waveguide surface, is also perpendicular to the waveguide surface. That is, the outgoing ray f is parallel to the incident ray a, but in the opposite direction.

[0070] Since the diffraction process involves multiple diffraction orders, the grating can be designed to retain only the required diffraction orders, while the energy of other diffraction orders is too low to be ignored. The above description only takes the zeroth and first order diffraction as an example, but its principle and process also apply to other diffraction orders and spatial direction processes, which will not be elaborated here.

[0071] Therefore, in some embodiments of the present invention, the incident light is coupled out after being modulated by gratings at least four times within the lens unit, wherein the first diffraction grating region 2 disposed on the first optical plane of the substrate 1 and the second diffraction grating region 3 disposed on the second optical plane of the substrate 1 opposite to the first optical plane are modulated at least twice. The grating modulation of the light is described in detail below. The light is diffracted by the grating into zero-order diffracted light and first-order diffracted light. The zero-order diffracted light does not change its wave vector component in the waveguide plane, while the first-order diffracted light changes its wave vector and its component in the waveguide plane. That is, in each diffraction of the light, the first-order diffracted light is considered to be modulated by the grating, while the zero-order light continues to propagate and undergoes the next diffraction. Furthermore, both the zero-order and first-order diffracted light alternately enter the two grating regions of the waveguide for diffraction, thereby achieving two-dimensional diffusion of the coupled light. It is understood that the first grating region and the second grating region can also be designed to retain zero-order diffraction rays and positive and negative first-order diffraction rays, or to retain other diffraction order rays. This can be changed by those skilled in the art as needed, but it is all within the framework of the technical solution of this invention.

[0072] After the image light emitted by the micro-projector 40 is coupled into the lens unit, it undergoes at least four total internal reflections and diffractions in the substrate 1 of the lens unit, achieving spatial expansion and coupling out. In other words, through the corresponding light transmission process, two-dimensional pupil expansion in at least two directions is achieved simultaneously, so that image light can be coupled out, for example, throughout the entire working area of ​​the diffraction grating.

[0073] It should be noted that the grating vector is a characteristic parameter of the diffraction grating, which depends on the orientation and spatial period of the grating. Specifically, the orientation of the grating vector is the positive and negative directions perpendicular to the grating grooves, and the magnitude of the grating vector is expressed as k = 2π / d, where d is the grating period.

[0074] The grating vector of the first diffraction grating region of the first optical plane of the lens unit, or the waveguide plate, can be denoted as two components k1=(±D) 1x±D 1y The grating vector of the second diffraction grating region of the second optical plane can be denoted as k2=(±D). 2x ±D 2y ).

[0075] According to the present invention, the grating period can be set to an appropriate size so that only 0th and 1st order diffracted light can be generated during the propagation and diffusion of image light in the waveguide sheet.

[0076] The amplitude of the incident light wave vector can be expressed in terms of the wave number: k r =2π / λ, where λ represents the wavelength of the diffracted light. It has two directional components k within the waveguide plane. rx and k ry The wave number in air can be denoted as k. r0 When it enters the medium, the wavenumber can be expressed as k. rn =k0*n, where n is the refractive index of the material.

[0077] Incident light k r0 The first-order diffracted light, after passing through the first diffraction grating region of the first optical plane of the waveguide, can have its wave vector expressed as k. r1 The diffraction inflection effect of the grating can be described by the diffraction equation, and its vector form in the waveguide plane can be expressed as:

[0078] (k) r1x k r1y ) = (k r0x +D 1x k r0y +D 1y )

[0079] Diffraction light k r1 The light received by the second diffraction grating region of the second optical plane produces first-order diffraction, and the resulting wave vector can be expressed as k. r2 Similarly, we have:

[0080] (k r2x k r2y )=(k r1x +D 2x k r1y +D 2y )

[0081] The first diffraction grating region of the first optical plane receives diffracted light k again. r2 The resulting first-order diffraction wave vector can be expressed as k r3 Similarly, we have:

[0082] (k r3x k r3y )=(k r2x +D1’x k r2y +D 1’y)

[0083] The second diffraction grating region of the second optical plane receives the diffracted light k. r3 The resulting first-order diffraction wave vector can be expressed as k r4 Similarly, we have:

[0084] (k r4x k r4y )=(k r3x +D 2’x k r3y +D 2’y )

[0085] =(k r0x +D 1x +D 2x +D 1’x +D 2’x k r0y +D 1y +D 2y +D 1’y +D 2’y )

[0086] Waveguides must meet the achromatic imaging condition, meaning that after image light of different wavelengths is diffused and propagated by the waveguide and finally coupled out, the direction of the outgoing light is the same as the direction of the incident light. In other words, the incident light wavenumber (k...) r0x k r0y ) and the emitted light wavenumber (k r4x k r4y )have:

[0087] (k) r0x k r0y ) = (k r4x k r4y )

[0088] Therefore, the grating vector of the waveguide plate must satisfy:

[0089] D 1x +D 2x +D 1’x +D 2’x = D 1y +D 2y +D 1’y +D 2’y =0

[0090] Due to the presence of a grating in the first optical plane region of the waveguide:

[0091] D 1x =- D 1’x D 1y =- D1’y

[0092] The existence of the grating in the second optical plane region is related to:

[0093] D 2x =- D 2’x D2y=- D 2’y

[0094] Therefore, it must satisfy the achromatic imaging condition (k) r0x k r0y ) = (k r4x k r4y Since the grating vectors k1 and k2 depend on the grating period and are independent of the light wavelength, according to the technical solution proposed by the present invention, the grating vectors satisfy this condition, and any wavelength also satisfies the achromatic imaging condition.

[0095] Figure 5 The diagram illustrates the grating vector k during the diffraction transmission process. The image light emitted by the micro-projector 40, for example, undergoes two diffractions coupled into the waveguide in the overlapping region of the gratings. The light reversal effect produced by these two diffractions can be represented by the superposition of the two coupled grating vectors: k incouple1 With k incouple2 After being coupled in, the light undergoes several total internal reflections and two (or more) decoupling diffractions before exiting the waveguide. The effect of this grating decoupling on the light's reversal can be represented by the superposition of two decoupling grating vectors: k decouple1 With k decouple2 The sum of the four grating vectors mentioned above is equal to or close to zero, that is, below a certain threshold. Therefore, the angle of the light rays coupled out of the waveguide remains basically unchanged, that is, consistent with (or negative of) the light rays coupled in, so that the image can be diffused and transmitted.

[0096] In the illustrated embodiment, since the periods on the two grating surfaces remain constant, the following relationship exists: |k incouple1 |=|k decouple1 |,|k incouple2 |=|k decouple2 The vectors are equal in magnitude but opposite in direction to the coupled and decoupled grating vectors on each grating surface. Therefore, their vector superposition diagram forms a parallelogram, particularly a rhombus, with the grating vectors returning to the origin, ensuring a zero vector sum. These measures avoid the image quality degradation caused by non-zero vector sums in traditional processes and waveguide structures, and reduce the requirements for lens unit design and manufacturing.

[0097] In some other embodiments, the grating vector k-map may not be a rhombus, but a conventional parallelogram. In these schemes, the sum of the four grating vectors is still guaranteed to be zero because the light rays are diffracted twice by the same grating in the four diffractions in the waveguide. That is, opposite sides in the grating vector k-map are always parallel and equal in magnitude (i.e., the coupled grating vector and the decoupled grating vector), so their vector sum must be zero. This ensures the parallelism of the incident and outgoing light rays of the waveguide, guaranteeing the image quality input to the human eye.

[0098] In some embodiments, the diffraction grating is designed as a coupling element, and it must be ensured that the diffraction angle of the generated target diffracted light is limited to the total reflection angle and the maximum propagation angle (θ). max Between ), this constraint can be expressed by the following physical relationship:

[0099]

[0100] Among them, |k r | represents the amplitude of the target light wave vector, n is the refractive index of the optical material, and λ0 is the center wavelength of the image light source. The left side of this inequality represents the lower limit of the light wave vector imposed by the total internal reflection angle, and the right side represents the upper limit of the light wave vector imposed by the maximum transmission angle of the waveguide. In some embodiments, the maximum transmission angle θ max It can reach up to 75°.

[0101] Specifically, the light wave vector |k r | Need to be less than Figure 5 Effective transmission can only be ensured if the outer radius of the waveguide, i.e., the upper limit, is greater than the inner radius, i.e., the lower limit. Therefore, during transmission, the end of the optical wave vector needs to be within the annular shadow region, returning to the origin only when coupled out. The outer radius is determined by the refractive index n of the waveguide material, the center wavelength λ0, and the maximum angle θ. max The function.

[0102] As an example, the thickness of the substrate 1 of the lens unit can be in the range of 0.3 to 2.5 mm, and the refractive index of the optical material can be 1.4 to 2.2, wherein the material can be optical glass or optical resin. The grating can be, for example, a surface relief grating, especially a one-dimensional surface relief grating, with a period of, for example, 200 to 600 nm.

[0103] The one-dimensional surface relief grating can be a positive grating, a blazed grating, a tilted grating, or a sinusoidal grating. The groove depth of the grating can be 40~500nm.

[0104] In some embodiments of the present invention, a grating structure is respectively provided in the first diffraction grating region 2 and the second diffraction grating region 3 of the waveguide sheet. Light is output to the human eye after being modulated by the gratings at least four times within the waveguide sheet, wherein the two grating structures modulate the light at least twice, for example... Figure 5 The light wave k-diagram shown is a parallelogram-shaped vector superposition. Figure 5 In the vector superposition diagram shown, the opposite sides of the parallelogram are the same grating structure, thus ensuring that the opposite sides are always parallel and equal in size. Therefore, the superposition of the four grating vectors is always zero, guaranteeing that the input and output light rays of the waveguide are parallel, thereby improving the image quality input to the human eye. In other words, in this invention, the light rays undergo at least four grating modulations through the first diffraction grating region 2 and the second diffraction grating region 3 on the upper and lower surfaces, ensuring that the output light rays maintain the same direction as the input light rays, thus guaranteeing the image quality input to the human eye.

[0105] Figure 6 This is a schematic diagram of the groove structure of the grating region 6 according to some embodiments of the present invention. Figure 6 In the schematic diagram, the vertical direction is used as the y-axis of the rectangular plane coordinate system, and the horizontal direction is used as the x-axis of the rectangular plane coordinate system. Here, within the plane of the waveguide sheet, the grating vector of the first diffraction grating region 2 and the grating vector of the second diffraction grating region 3 of the waveguide sheet can be set to be axisymmetric, especially about the vertical direction, or the y-axis.

[0106] In some embodiments, the first diffraction grating region 2 and the second diffraction grating region 3 may have the same grating periods T1 and T2, and / or the first diffraction grating region 2 and the second diffraction grating region 3 may have the same grating structure. However, the first grating vector of the first diffraction grating region 2 may be different from the second grating vector of the second diffraction grating region 3.

[0107] like Figure 6 As shown, solid lines represent the grating groove lines of the first diffraction grating region 2, and dashed lines represent the grating groove lines of the second diffraction grating region 3. For example, the grating groove lines of two linear diffraction grating regions can form an acute angle θ, especially within the range of 40° to 90°, particularly 60°. Therefore, assuming that one of the diffraction grating regions is flipped 180° around the x-axis or y-axis, the grating structure of this flipped diffraction grating region should overlap or at least partially overlap with the grating structure of the other diffraction grating region.

[0108] By making the grating structures in the diffraction grating regions completely or at least partially overlap symmetrically about the xy plane, the same mold or process can be used to fabricate the grating structure in the first diffraction grating region 2 and the second diffraction grating region 3. This simplifies the imprinting mold for fabricating the grating, simplifying the process, reducing production costs, and facilitating stable mass production. Furthermore, since this invention can set only two grating vectors, it offers greater freedom in process design, a simpler structure, and is easier to process stably in mass production, thus possessing high industrial application value.

[0109] It should be noted that, according to some embodiments of the present invention, the first diffraction grating region 2 disposed on the first optical plane of the substrate 1 can be a continuous region, and / or the second diffraction grating region 3 disposed on the second optical plane of the substrate 1 opposite to the first optical plane can also be a continuous region. That is, the diffraction grating regions on each optical plane form a whole region without interruption.

[0110] Here, for example, it is also possible to choose a diffraction grating region that is continuous across the entire optical plane, i.e., continuously covering the entire optical plane, and all grating regions on the same optical plane have a consistent grating vector. For example, the first diffraction grating region 2 has a consistent first grating vector and is continuous across the entire first optical plane of the substrate 1, i.e., continuously covering the entire first optical plane, and / or the second diffraction grating region 3 has a consistent second grating vector and is continuous across the entire second optical plane of the substrate 1, i.e., continuously covering the entire second optical plane.

[0111] According to other embodiments of the present invention, the first diffraction grating region 2 disposed on the first optical plane of the substrate 1 may also be a discontinuous region, and / or the second diffraction grating region 3 disposed on the second optical plane of the substrate 1 opposite to the first optical plane may be a discontinuous region. That is, the diffraction grating regions on a particular optical plane may be constructed as multiple separate grating regions, with a substrate region without a grating structure between these separate grating regions. According to the present invention, the multiple separate grating regions on the first optical plane all have a consistent first grating vector, while the multiple separate grating regions on the second optical plane all have a consistent second grating vector.

[0112] Of course, depending on the product design requirements and photoelectric performance needs, the first diffraction grating region 2 on the first optical plane of the substrate 1 and the second diffraction grating region 3 on the second optical plane of the substrate 1 opposite to the first optical plane can be constructed as continuous and / or discontinuous, that is, on the optical planes on both sides of the substrate, the diffraction grating regions can be arbitrarily combined in a continuous or discontinuous structural form.

[0113] Figures 7(a)-(d) are schematic diagrams of grating types according to some embodiments of the present invention. The diffraction grating according to the present invention is an optical element with a periodic structure. The periodic structure can be peaks and valleys embossed on the surface of a material, i.e., a surface relief grating (SRG), or "bright and dark interference fringes" formed by holographic exposure inside the material, i.e., a volume holographic grating (VHG). Both ultimately cause a periodic change in the refractive index n.

[0114] According to some embodiments of the present invention, the specific grating structure may be, for example, a surface relief grating, including but not limited to a positive grating, a blazed grating, a tilted grating, or a sinusoidal grating, as shown in Figures 7(a)-(d), respectively. For example, a tilted grating or a triangular blazed grating can maximize the coupling efficiency of light diffracted in the direction of the eye.

[0115] It should be noted that the diffraction angle corresponding to each diffraction order is determined by the incident angle of the light, the period of the grating, and the groove angle along the grating direction. By designing other parameters of the grating, including but not limited to the material refractive index n, grating shape, thickness, and duty cycle, the diffraction efficiency of a certain diffraction order (i.e., a certain direction) can be optimized to the highest level, so that most of the light propagates mainly along this direction after diffraction. Therefore, by appropriately designing the grating structure and optical path, the technical solution proposed in this invention can simultaneously achieve optimal FOV, optical efficiency, and image sharpness.

[0116] In addition, the groove depth, duty cycle or shape of the single-sided coupling grating of the waveguide sheet can be modulated, or both sides of the coupling grating of the waveguide sheet can be modulated to make the light coupling intensity uniformity in each region better.

[0117] The disclosed content also provides a lens unit, including a substrate made of optical waveguide material having a first optical plane and a second optical plane opposite to the first optical plane. The lens unit further includes a first diffraction grating region and a second diffraction grating region, wherein the diffraction grating region disposed on the first optical plane of the substrate constitutes the first diffraction grating region, and the diffraction grating region disposed on the second optical plane of the substrate opposite to the first optical plane constitutes the second diffraction grating region. Here, a coupling and deflection region for incident light is provided on the first optical plane of the substrate, wherein the coupling and deflection region disposed on the first optical plane of the substrate has a consistent grating vector with the coupling and deflection region disposed on the first optical plane of the substrate. In some variations, a coupling and deflection region for incident light may also be additionally or alternatively provided on the second optical plane of the substrate, wherein the coupling and deflection region disposed on the second optical plane of the substrate has a consistent grating vector with the coupling and deflection region disposed on the second optical plane of the substrate.

[0118] In some variations, the portion of the diffraction grating region outside the coupling-in and turning regions constitutes a coupling-out region for light to be coupled out of the lens unit. Thus, the first diffraction grating region on the first optical plane of the substrate consists of the coupling-in and turning regions and the coupling-out region located on the first optical plane, and / or the second diffraction grating region on the second optical plane of the substrate opposite to the first optical plane consists of the coupling-in and turning regions and the coupling-out region located on the second optical plane.

[0119] Therefore, coupling and turning regions for coupling and turning image rays and coupling and detaching regions for coupling out image rays can be arbitrarily set in the substrate 1 of the lens unit or waveguide sheet. For the proposed lens unit, the coupling and turning regions can be set in any way and shape according to the optical design and structural design requirements. Outside the coupling and turning regions, the remaining parts of the first diffraction grating region 2 and the second diffraction grating region 3 are used as the coupling out regions.

[0120] In other words, fixed coupling and turning regions can be set on the substrate 1 of the lens unit, while the remaining diffraction grating region is used as the coupling out region. Here, the function of the coupling and turning regions is to, on the one hand, couple the image light into the lens unit or waveguide, and on the other hand, turn the image light to the desired propagation direction after being modulated by the coupling and turning regions.

[0121] Figure 8 This is a schematic diagram of the coupling-in and turning regions and the coupling-out region of a lens unit according to some embodiments of the present invention, wherein the coupling-in and turning region a is provided only in one of the optical planes. Figure 8 In one embodiment, for example, the first diffraction grating region of the lens unit includes an ingress and transition region, as shown by region a enclosed by solid lines. This single ingress and transition region a is tightly connected to and completely surrounded by the outgress region b of the optical plane. In fact, outside of the ingress and transition region a, the remaining working area of ​​the diffraction grating can be entirely used as the outgress region for the emitted light rays, gradually guiding the image light rays out of the waveguide and into the human eye during diffraction. In this embodiment, since the ingress and transition region a is only provided in the first diffraction grating region of the lens unit, the outgress region can include the portion of the first diffraction grating region outside the ingress and transition region a, as well as the entire second diffraction grating region opposite it.

[0122] Since the portion of the diffraction grating region outside the coupling-in and turning regions a can be used as the coupling-out regions, and the coupling-in and turning regions a are completely surrounded by the coupling-out regions b on the optical plane, there is no total reflection surface between the coupling-in and turning regions and the coupling-out regions contained in the diffraction grating region in this embodiment. This avoids the phase shift caused by the light beam hitting the boundary between the grating structure and the total reflection surface. Therefore, the light in this embodiment does not produce a phase change during propagation, and has the advantage of higher image clarity compared to traditional waveguide sheets.

[0123] In the illustrated embodiment, a coupling and deflection region for incident light is provided on a first optical plane of substrate 1, wherein this coupling and deflection region on the first optical plane of substrate 1 has the same or identical grating vector as the coupling and deflection region on the first optical plane of substrate 1. Alternatively or additionally, a coupling and deflection region for incident light may also be provided on a second optical plane of substrate 1, wherein the coupling and deflection region on the second optical plane of substrate 1 has the same grating vector as the coupling and deflection region on the second optical plane of substrate 1.

[0124] One approach is to define the first and second diffraction regions experienced by the incident light as the coupling and transition regions, such as... Figure 8 As shown in region a, the coupling region portion in the same optical plane is as follows: Figure 8 The region b is shown in the diagram (excluding region a).

[0125] In some embodiments, the gratings in the coupling-in and transition regions and the coupling-out regions in the optical plane can have the same groove depth and duty cycle. This simplifies the manufacturing process while still achieving the required optical performance. Furthermore, in some variations, the grating groove depth and duty cycle in the coupling-in and transition regions can be greater than those in the surrounding coupling-out regions. This increases the coupling efficiency and field of view of the light source. Variations in the grating groove depth and duty cycle can effectively increase the coupling efficiency of the light source, increase light energy utilization, and expand the coupling field of view. It should be noted that adjusting the grating groove depth and duty cycle does not change the grating vector but does affect the diffraction efficiency. The relationship between the groove depth and duty cycle of the gratings in the coupling-in and transition regions and the coupling-out regions in the optical plane described herein also applies to the following embodiments provided in this application.

[0126] The solution proposed in this invention allows any diffraction grating region to be configured as the coupling-in and transition regions, while the remaining portion of the diffraction grating region can be used as the coupling-out region. For example, the grating groove depth of the coupling-in and transition regions can be 150~600nm, and the grating period and grating orientation can be consistent with the coupling-out region in the optical plane.

[0127] Figure 9 This is a schematic diagram of the coupling-in and transition regions and the coupling-out region of a lens unit according to some embodiments of the present invention. Here, a coupling-in and transition region are respectively provided in the first and second diffraction grating regions of the lens unit. In this embodiment, since the portion of the diffraction grating region 6 outside the coupling-in and transition regions can be used as the coupling-out region, the coupling-in and transition regions on both sides of the waveguide sheet are completely surrounded by the corresponding coupling-out region b. Figure 8 The main difference compared to the embodiment is that an additional coupling and turning region for incident light is provided on the second optical plane of the substrate 1, wherein this coupling and turning region on the second optical plane of the substrate 1 has the same grating vector as the coupling out region on the second optical plane of the substrate 1.

[0128] The coupling and turning regions can coexist in the first and second diffraction grating regions simultaneously. The coupling and turning regions of the two surfaces have an overlap, meaning that in the plane where the lens unit is located, the coupling and turning regions on the first optical plane of substrate 1 and the coupling and turning regions on the second optical plane of substrate 1 have at least partial overlap, such as... Figure 9 As shown. In Figure 9 In the diagram, shaded region c represents the superimposed region, region d represents the region remaining after removing the superimposed region from the coupling and turning regions of the first optical plane, and region e represents the region remaining after removing the superimposed region from the coupling and turning regions of the second optical plane.

[0129] Here, for example, the superimposed region c can serve as the coupling region of the incident light, while regions d and e can serve as the turning regions of the light. That is, the coupling and turning regions include the coupling region c and the turning regions d and e. The coupling region c can be a circle as shown in the diagram, or it can be a triangle, rectangle, ellipse, etc. The turning regions d and e can be the shapes shown in the diagram, or they can be any polygon. In some variations, the contours of the coupling and turning regions on the two surfaces of the waveguide sheet can have a mirror symmetry relationship. That is, when the waveguide sheet is rotated 180° around the x-axis or y-axis, the structures of the grating regions 6 on both surfaces completely overlap, thereby saving on manufacturing molds and facilitating fabrication. Of course, depending on the design and performance requirements, the contours and / or positions of the coupling and turning regions on the two surfaces of the waveguide sheet can also be made to correspond perfectly.

[0130] In this embodiment, since the portion of the diffraction grating region outside the coupling-in and turning regions can be used as the coupling-out region, and the coupling-in and turning regions are completely surrounded by the coupling-out regions in the optical plane, there is no total reflection surface between the coupling-in and turning regions and the coupling-out regions contained in the diffraction grating region. This avoids the phase shift caused by the light beam hitting the boundary between the grating structure and the total reflection surface. Therefore, the light in this embodiment does not produce a phase change during propagation, and has the advantage of higher image clarity compared to traditional waveguide sheets.

[0131] Figure 10 This is a schematic diagram of the coupling-in and turning regions and the coupling-out region of a lens unit according to some embodiments of the present invention. Here, the coupling-in and turning regions are respectively connected to the corresponding coupling-out regions. In this embodiment, as shown in the figure, the coupling-in and turning regions on both sides of the waveguide sheet are only partially connected to the corresponding coupling-out regions b in the optical plane, rather than being completely surrounded by the coupling-out regions b.

[0132] Figure 11 This is a schematic diagram of the coupling-in and turning regions and the coupling-out region of a lens unit according to some embodiments of the present invention. Here, the coupling-in and turning regions are completely outside the coupling-out region in the optical plane, that is, they are not connected to the corresponding coupling-out region. In this embodiment, since the coupling-in and turning regions are completely separated from the corresponding coupling-out regions, the entire diffraction grating region on both sides of the waveguide sheet can be used as the coupling-out region b. In this case, the first diffraction grating region provided on the first optical plane of the substrate and the second diffraction grating region provided on the second optical plane of the substrate opposite to the first optical plane are both constructed as discontinuous or discontinuous, and are respectively divided into the coupling-in and turning regions and the coupling-out region.

[0133] like Figure 11 As shown, the coupling-in and turning regions are not directly connected to or adjacent to the coupling-out regions of the optical plane, but are separated from each other. Although the grating structures in the coupling-in and turning regions form separate regions from the grating structures in the coupling-out regions of the optical plane, all grating structures on the same optical plane still have the same or identical grating vector.

[0134] According to some embodiments of the present invention, if the uniformity of the output pupil is not high, the output region b can be set as a uniform grating, i.e., having a consistent groove depth and duty cycle. If a high uniformity requirement is required for the output pupil, the output region can be set as a variable grating, i.e., the farther the output region b is from the input region c, the greater its grating groove depth and duty cycle. Furthermore, the groove depth, duty cycle, or tooth profile of a single-sided output grating can be modulated, or both output grating surfaces can be modulated to achieve better uniformity of light output intensity in each region.

[0135] exist Figures 8 to 11 Based on the illustrated embodiment, one or more coupling and turning regions may be provided on each optical plane, and the coupling and turning regions on both sides of the waveguide sheet may be arranged in a mirror symmetry or in an axially symmetric manner in the plane of the waveguide sheet. In some modified embodiments, one or more, especially two, coupling and turning regions may be provided on one optical plane, while the other optical plane may not have coupling and turning regions.

[0136] According to the present invention, the relative positional relationship between the coupling-in and turning regions and the coupling-out regions on the optical plane can also be varied. For example, the coupling-in and turning regions can be completely located in the coupling-out regions, partially connected to the coupling-out regions, or completely separated from the coupling-out regions. In other words, since the portion of the diffraction grating region outside the coupling-in and turning regions can be used as the coupling-out regions, the coupling-in and turning regions c, d, and e can be included in, partially included in, or separated from the grating coupling-out region b.

[0137] According to the present invention, when viewed in a direction perpendicular to the waveguide plate plane, the coupling and turning regions provided on the first optical plane of the substrate 1 and the coupling and turning regions provided on the second optical plane of the substrate 1 preferably have corresponding overlapping regions. That is, although the coupling and turning regions are located on both sides of the waveguide plate, the projections of these coupling and turning regions on the waveguide plate plane can have overlapping regions.

[0138] Furthermore, the first diffraction grating region 2 disposed on the first optical plane of the substrate 1 can be configured as a continuous region, and / or the second diffraction grating region 3 disposed on the second optical plane of the substrate 1 opposite to the first optical plane can also be configured as a continuous region. In this case, the corresponding coupling-in and turning regions can be completely or partially contained in the corresponding coupling-out regions, that is, become part of the overall grating structure.

[0139] It should also be noted that the first diffraction grating region 2 on the first optical plane of the substrate 1 and the second diffraction grating region 3 on the second optical plane of the substrate 1 opposite to the first optical plane can have the same or different structures and shapes. Similarly, the coupling-in and turning regions and coupling-out regions on both sides of the substrate 1 can also have the same or different structures and shapes. Their specific arrangement, structure, shape and optical parameters can be adjusted and different combinations can be adopted according to specific design and performance requirements. All of these are within the scope of this invention.

[0140] The technical solution proposed in this invention can significantly simplify the design and manufacturing difficulty of lens units and AR devices, enabling the waveguide sheet structure to flexibly and reliably match optical performance requirements and mechanical structure needs, thus meeting the dual requirements of product performance and manufacturing cost.

[0141] The lens unit proposed in this invention can be flexibly applied to various augmented reality (AR) devices, such as AR glasses, head-up displays, and other wearable electronic devices.

[0142] According to the present invention, an AR device, particularly AR glasses, is also proposed, which includes, for example, a frame for mounting lens units, temples for wearing AR glasses, a left lens unit and a right lens unit mounted in the frame, a computing unit for data processing and generating image signals, and a micro projector, wherein the micro projector outputs an image based on the image signal generated by the computing unit.

[0143] Using the technical solution proposed in this invention, coupling and transition regions can be arbitrarily set on the optical plane of the substrate of the lens unit. The following detailed description, using AR glasses as an example, illustrates an AR device employing the aforementioned lens unit.

[0144] Figure 12 This is a schematic diagram of AR glasses according to some embodiments of the present invention, wherein the AR device described herein is AR glasses.

[0145] As shown in the figure, the AR glasses include a frame 60 for mounting lens units, temples 90 for wearing the AR glasses, and a left lens unit 10 and a right lens unit 20 mounted in the frame 60. The temples 90 can be connected to the frame 60 in any manner, such as flexibly or by hinges, to form the main body of the AR glasses. Electronic and optical components of the AR glasses can be selectively mounted on the temples 90 and / or the frame 60, or embedded / embedded in their material. These electronic and optical components include, but are not limited to, a computing unit 50 for data processing and generating image signals, a camera 30, a microprojector 40 for outputting images based on the image signals generated by the computing unit 50, a microdisplay, a spatial sensor, and a position sensor.

[0146] The lens unit (waveguide sheet) is the display component in the AR device. Figure 12 In the illustrated embodiment, the AR glasses include a left lens unit 10 (left eye waveguide display system) and a right lens unit 20 (right eye waveguide display system), wherein the camera 30 can be positioned in the center between the left lens unit 10 and the right lens unit 20, that is, approximately in the center above the bridge of the nose. A microprojector 40 and a computing unit 50 are, for example, located in the temple 90.

[0147] It should be noted that the optical and electronic components included in AR glasses can be flexibly selected according to design requirements and arranged arbitrarily according to structural conditions, and are not limited to the forms given in the examples. For example, the left lens unit 10 and the right lens unit 20 can be constructed as two separate lens units, or as two components of a single integral lens unit. Figure 12 In the example, the camera 30 is positioned in the center between the left lens unit 10 and the right lens unit 20, but other suitable optical and electronic components can also be positioned in this location, as will be described in detail in later embodiments.

[0148] During operation, the microdisplay in the microprojector 40 displays an image, which is then input through the projection lens to the coupling and deflection area of ​​the optical waveguide lens, and then transmitted to the human eye through a series of light transmissions. The computing unit 50 can not only provide image signals to the microdisplay, but also communicate with other components in the system, such as the camera 30, space sensor, position sensor, and microprojector 40.

[0149] The microdisplays that can be used here include, but are not limited to, digital light processors (DLP), liquid crystal on silicon (LCoS), organic light-emitting diodes (OLEDs), and micro LEDs. The high transmittance of the waveguide lens allows users to clearly observe the real world.

[0150] Camera 30 and the spatial sensor can be an RGB camera, a monochrome camera, an eye-tracking sensor, and a depth camera, or a combination thereof. The RGB or monochrome camera can capture environmental images of the real scene, the eye-tracking sensor can realize eye tracking, and the depth camera can acquire depth information of the scene to realize functions such as face and gesture recognition.

[0151] The position sensor can be a combination of an accelerometer, gyroscope, magnetometer, and GPS receiver. After processing the signals from the position sensor, the computing unit 50 can more accurately overlay virtual images onto the real environment.

[0152] Figure 13 This is a schematic diagram of AR glasses according to some embodiments of the present invention, featuring a modified glasses shape. For example... Figure 13 As shown, the AR glasses include a frame 60 for mounting lens units, temples 90 for wearing the AR glasses, and a left lens unit 10 and a right lens unit 20 mounted in the frame 60. Here, as an example, the left lens unit 10 and the right lens unit 20 are configured as two separate lens units, each mounted in the frame 60.

[0153] and Figure 12 The difference in the illustrated embodiment is that, in Figure 13In the illustrated embodiment, the lens unit mounted in the frame 60 employs a chamfered design. That is, for example, based on a basic rectangular shape, the lens unit has a chamfered shape at at least one right angle. Correspondingly, the frame 60 of the AR glasses can also adopt a chamfered shape that matches the chamfered shape of the lens unit. For example, the waveguide sheet can be constructed as a square with a notched corner, thereby matching the shape of the waveguide sheet's transition area. This not only reduces the size of the AR glasses but also accommodates the structural space requirements of different components and allows for more flexible and varied product designs. Of course, the waveguide sheet can also be constructed as any other shape with a notched corner or chamfer, such as a rectangle or polygon.

[0154] In some modified designs, the frame 60 may not have a chamfered shape. Instead, the frame 60 may have space for mounting components at a location corresponding to the chamfered shape of the lens unit. Thus, electronic components or other devices can be installed at the chamfered corner of the lens unit of the frame.

[0155] Figure 14 This is a schematic diagram of AR glasses according to some embodiments of the present invention. Figure 14 As shown, the overall structure of the AR glasses is similar to that in the previous embodiment. The AR glasses include a frame 60 for mounting the lens units, temples 90 for wearing the AR glasses, and a left lens unit 10 and a right lens unit 20 mounted in the frame 60. In this embodiment, the left lens unit 10 and the right lens unit 20 mounted in the frame 60 are constructed as a single lens unit. In other words, the left lens unit 10 and the right lens unit 20 are formed by different components of a single lens unit. Therefore, the substrate 1 made of optical waveguide material for the left lens unit 10 and the right lens unit 20 is continuous and integral.

[0156] For this purpose, a separate light guide element 70 can be provided, which guides the image light from the microprojector 40, or microdisplay, to the coupling and turning region 35 of the lens unit. Through the light guide element 70, the left lens unit 10 and the right lens unit 20 can share a single microprojector 40 or microdisplay. Alternatively, the coupling and turning region 35 can be positioned at the geometric center of the waveguide sheet, for example, on the axis of symmetry. One end of the light guide element 70 is connected to the microprojector 40, and the other end is connected to the coupling and turning region 35 of the lens unit, thereby transmitting image light from the microprojector 40 or microdisplay to the lens unit.

[0157] In the illustrated embodiment, the coupling and turning region 35 is positioned at the center between the left lens unit 10 and the right lens unit 20, roughly at the center above the bridge of the nose. This facilitates uniform and coordinated image transmission between the left and right lens units 10 and 20. Simultaneously, by utilizing a suitably shaped light guide element 70, such as an optical fiber, components such as the display system's computing unit 50, micro-projector 40, or microdisplay can be positioned appropriately within the AR device. This allows for efficient use of structural space, flexible design, and ensures high-quality image transmission and display. Figure 14 In one embodiment, the micro-projector 40 and the computing unit 50 are mounted on one of the temples 90. The image light is transmitted from the micro-projector 40 through the light guide element 70 to the coupling and turning region 35 of the lens unit, enters the lens unit through the coupling and turning region 35, and finally enters the human eye through the coupling region by means of total internal reflection and diffraction propagation.

[0158] Figure 15 This is a schematic diagram of AR glasses according to other embodiments of the present invention. In this embodiment, the possibility of arranging optical and electronic components in different ways is shown as an example. Figure 12-11 In the illustrated embodiment, the camera 30 is positioned in the center between the left lens unit 10 and the right lens unit 20, roughly in the center above the bridge of the nose. In contrast, in... Figure 15 In this embodiment, instead of camera 30, microprojector 40 or microdisplay can be directly positioned in the center between left lens unit 10 and right lens unit 20, roughly in the center above the bridge of the nose. Therefore, the image light emitted by microprojector 40 or microdisplay can directly enter the lens unit through the coupling and turning area, eliminating the need for the intermediate light guide element 70.

[0159] Similarly, considering the specific shape and spatial structure of the AR device, the arrangement and method of other optical and electronic components can also be changed. For example, in Figure 15 In the example, sensors 80, including position sensors and / or spatial sensors, can be arranged in one or both temples 90. Clearly, while meeting the structural and operational requirements of the optical and electronic components of the AR device, the shape of the lens unit can be changed, and the positions of different components can be flexibly set.

[0160] It should be noted that the technical solutions presented herein are not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the inventive concept of this invention, and all such modifications and variations fall within the protection scope of this invention.

Claims

1. A lens unit, characterized in that, include: A substrate (1) made of optical waveguide material has a first optical plane and a second optical plane opposite to the first optical plane; as well as The first diffraction grating region (2) and the second diffraction grating region (3) are provided on the first optical plane of the substrate (1) to form the first diffraction grating region (2), and the diffraction grating region provided on the second optical plane of the substrate (1) opposite to the first optical plane to form the second diffraction grating region (3). The light is modulated by the first diffraction grating region and the second diffraction grating region at least four times, and the angle of the coupled light is the same as or negative of the coupled light. In this embodiment, coupling and turning regions for incident light are provided on the first optical plane and / or the second optical plane of the substrate (1), and the part of the diffraction grating region outside the coupling and turning regions is the coupling out region, and the coupling and turning regions are completely surrounded by the coupling out region on the optical plane.

2. The lens unit according to claim 1, wherein, The first diffraction grating region (2) on the first optical plane of the substrate (1) is a continuous region, and / or the second diffraction grating region (3) on the second optical plane opposite to the first optical plane of the substrate (1) is a continuous region.

3. The lens unit according to claim 2, wherein, The first diffraction grating region (2) is continuous on the entire first optical plane of the substrate (1), and / or the second diffraction grating region (3) is continuous on the entire second optical plane of the substrate (1).

4. The lens unit according to claim 1, wherein, The first grating vector of the first diffraction grating region (2) is different from the second grating vector of the second diffraction grating region (3).

5. The lens unit according to claim 1, wherein, The first diffraction grating region (2) on the first optical plane of the substrate (1) and the second diffraction grating region (3) on the second optical plane of the substrate (1) opposite to the first optical plane modulate the incident light at least twice.

6. The lens unit according to claim 1, wherein, The first diffraction grating region (2) on the first optical plane of the substrate (1) and the second diffraction grating region (3) on the second optical plane opposite to the first optical plane of the substrate (1) have the same grating period.

7. The lens unit according to claim 1, wherein, In the plane where the lens unit is located, the grating groove line of the first diffraction grating region (2) and the grating groove line of the second diffraction grating region (3) have an angle of 40~90°.

8. The lens unit according to claim 7, wherein, The grating groove lines of the first diffraction grating region (2) and the grating groove lines of the second diffraction grating region (3) have an angle of 60°.

9. The lens unit according to claim 1, wherein, During the diffraction propagation process of the lens unit, the diffraction angle of the diffracted light satisfies the formula: In the formula | k r | represents the amplitude of the target light wave vector, n is the refractive index of the optical waveguide material, λ0 is the center wavelength of the image light source, and θ max Indicates the maximum transmission angle.

10. The lens unit according to any one of claims 1 to 9, wherein, The optical waveguide material constituting the substrate (1) is optical glass or optical resin.

11. The lens unit according to any one of claims 1 to 9, wherein, The first diffraction grating region (2) on the first optical plane of the substrate (1) and the second diffraction grating region (3) on the second optical plane opposite to the first optical plane of the substrate (1) include surface relief gratings.

12. The lens unit according to claim 11, wherein, The first diffraction grating region (2) on the first optical plane of the substrate (1) and the second diffraction grating region (3) on the second optical plane opposite to the first optical plane of the substrate (1) include positive grating, blazed grating, tilted grating or sinusoidal grating.

13. The lens unit according to any one of claims 1 to 9, wherein, The first diffraction grating region (2) disposed on the first optical plane of the substrate (1) and the second diffraction grating region (3) disposed on the second optical plane of the substrate (1) opposite to the first optical plane at least partially overlap each other on both sides of the substrate (1).

14. The lens unit according to any one of claims 1 to 9, wherein, In the plane where the lens unit is located, the grating vector of the first diffraction grating region (2) and the grating vector of the second diffraction grating region (3) are axially symmetric.

15. The lens unit according to any one of claims 1 to 9, wherein, The first diffraction grating region (2) on the first optical plane of the substrate (1) and the second diffraction grating region (3) on the second optical plane opposite to the first optical plane of the substrate (1) have the same groove structure.

16. The lens unit according to claim 14, wherein, The first diffraction grating region (2) on the first optical plane of the substrate (1) and the second diffraction grating region (3) on the second optical plane opposite to the first optical plane of the substrate (1) have the same groove structure.

17. The lens unit according to any one of claims 1 to 9, wherein, The lens unit is a transparent waveguide lens unit.

18. An AR device comprising at least one lens unit according to any one of claims 1 to 17.

19. The AR device according to claim 18, wherein, The AR device is AR glasses.

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