CN115485604A

CN115485604A - Lens unit and AR apparatus including the same

Info

Publication number: CN115485604A
Application number: CN202180031992.2A
Authority: CN
Inventors: 徐钦锋; 马珂奇; 杜佳玮
Original assignee: Ningbo Sunny Opotech Co Ltd
Current assignee: Ningbo Sunny Opotech Co Ltd
Priority date: 2020-04-29
Filing date: 2021-03-15
Publication date: 2022-12-16
Also published as: CN113568168A; WO2021218454A1; CN113568168B

Abstract

A lens unit comprises a substrate (1) made of an optical waveguide material, which has a first optical plane and a second optical plane opposite to the first optical plane, and a first diffraction grating area (2) and a second diffraction grating area (3), wherein the diffraction grating area provided on the first optical plane of the substrate (1) constitutes the first diffraction grating area (2) and the diffraction grating area provided on the second optical plane of the substrate (1) opposite to the first optical plane constitutes the second diffraction grating area (3), wherein the first diffraction grating area (2) has a uniform first grating vector on the first optical plane of the substrate (1) and the second diffraction grating area (3) has a uniform second grating vector on the second optical plane of the substrate (1) opposite to the first optical plane. An AR glasses including a lens unit that improves the quality of an image input to a human eye, and is simpler and less expensive to manufacture than a conventional waveguide lens unit.

Description

Lens unit and AR apparatus including the same

Technical Field

The present invention relates to a lens unit and an AR apparatus including the lens unit.

Background

The description herein is merely provided for background information related to the present invention and does not necessarily constitute prior art.

Augmented Reality (AR) technology is a new technology for seamlessly integrating real world information and virtual world information, and is to superimpose entity information which is difficult to experience in a certain time space range of the real world after simulation through scientific technologies such as computers, so that people can obtain sensory experience beyond Reality. Due to the characteristic that the augmented reality technology superposes virtual objects or pictures in a real environment, the augmented reality technology has great application potential in many fields.

The optical waveguide lens (lens unit) is a key core component in a new generation of augmented reality technology, combines a total reflection waveguide principle and a diffraction element, is used for copying an extended exit pupil in an imaging system, and has the advantages of large field of view, small volume, small weight and the like. The optical waveguide lens does not hinder people from observing a vertical real picture while transversely transmitting image light, so that the optical waveguide lens becomes an inevitable trend of the development of the AR technology.

In a typical optical waveguide technology, an image light source emitted from a microdisplay is projected into an incident grating region of a waveguide sheet through a projection lens. The entrance pupil light source is copied and expanded in two directions under the action of the total reflection transmission of the waveguide sheet and the diffraction grating, an expanded exit pupil is created in the coupling-out grating area, and the observation range of human eyes is enlarged. Typical diffraction optical elements that are currently used more often include two-dimensional cross gratings and butterfly-wing gratings, which are used for coupling in and out of a signal light source on a waveguide chip. The cross grating is a grating with a period in two dimensions, and the wing gratings are respectively provided with a turning grating area on two sides of the coupling grating. The cross grating is difficult to prepare, and the design freedom degree of the cross grating is lower than that of the butterfly wing grating (groove depth, inclination, filling factor and the like). The butterfly wing grating has four diffraction grating areas, so the tolerance requirement of the preparation is higher, and the preparation is also more difficult.

In the optical design of the waveguide plate, it is often required that the incident light of the in-coupling and turning region and the emergent light of the out-coupling region are kept parallel to transmit the image to human eyes completely without distortion, which requires that the sum of the grating vectors of the in-coupling and turning region and the out-coupling region related to the waveguide plate is zero, i.e. the sum of the grating vectors of the plurality of gratings of which the light is diffracted is zero. The design and preparation accuracy of the grating structure is very high, on one hand, the design of the grating structure needs to have high diffraction efficiency, and on the other hand, errors are bound to exist in the preparation of the grating, for example, the direction, the angle, the depth and the like of grating lines cannot be completely matched with the design, and certain errors exist. This results in the fact that the sum of all the associated grating vectors of the actually produced waveguide pieces is not necessarily zero, the incident light and the emergent light of the waveguide pieces cannot be kept parallel, and finally, the image input to the human eye has aberration and distortion.

The conventional waveguide plate adopts three or more grating structures including an incoupling grating, a turning grating and an outcoupling grating, the vector sum of the three gratings must be zero to ensure that input light and output light are parallel, however, manufacturing tolerance always exists when actually manufacturing the gratings, and the manufactured three grating structures cannot be completely matched with design values.

Disclosure of Invention

The present invention is directed to a lens unit and an AR device capable of improving the quality of an image input to human eyes, and more particularly, to a lens unit and an AR device capable of overcoming the defects of the prior art, simply and effectively keeping the outgoing light and the incoming light completely parallel, and achieving integration of coupling-in, pupil expanding, and coupling-out, and at the same time, having a simpler manufacturing process and lower cost compared to the conventional waveguide lens unit.

Thus, according to a first aspect of the present invention, a lens unit is presented comprising: a substrate composed of an optical waveguide material having a first optical plane and a second optical plane opposite the first optical plane; and

a first diffraction grating region and a second diffraction grating region, wherein the diffraction grating region provided on a first optical plane of the substrate constitutes the first diffraction grating region, and the diffraction grating region provided on a second optical plane of the substrate opposite to the first optical plane constitutes the second diffraction grating region;

wherein the first diffraction grating region has a uniform first grating vector on a first optical plane of the substrate and the second diffraction grating region has a uniform second grating vector on a second optical plane of the substrate opposite the first optical plane.

According to the technical scheme of the invention, after the light emitted by the micro projector is diffracted and coupled by the two diffraction grating surfaces, the light is diffused and transmitted through multiple total reflection and diffraction, and finally, an image can be seen in any area of the working part of the grating. According to the lens unit provided by the invention, as the lens unit only has two grating vectors, namely the first diffraction grating area has the consistent first grating vector on the first optical plane of the substrate and the second diffraction grating area has the consistent second grating vector on the second optical plane of the substrate opposite to the first optical plane, the lens unit has the advantages of high product design freedom, simple structure, easiness in mass production and processing and higher industrial application value.

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

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

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

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.

According to the invention, the light can be modulated by at least four times of gratings on the upper surface and the lower surface, the output light and the input light can keep consistent direction, and the image quality of the input human eyes is improved. According to some embodiments of the first aspect of the present invention, the incident light is coupled out after four grating modulations within the mirror plate unit.

According to some embodiments of the first aspect of the present invention, 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 modulate incident light twice, respectively.

According to some embodiments of the first aspect of the present invention, 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 have the same grating period.

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 40 to 90 ° in a plane in which the lens unit is located.

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

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

in the formula | k _r I represents the amplitude of the target light wave vector, n is the refractive index of the optical waveguide material, and lambda ₀ Is the center wavelength of the image light source, θ _max Representing the maximum transmission angle.

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

According to some embodiments of the first aspect of the present invention, 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 comprise surface relief gratings.

According to some embodiments of the first aspect of the present invention, 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 comprise a positive grating, a blazed grating, a tilted grating and/or a sinusoidal grating.

According to some embodiments of the first aspect of the present invention, 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 at least partially overlap with each other on both sides of the substrate.

According to some embodiments of the first aspect of the present invention, the grating vector of the first diffraction grating area and the grating vector of the second diffraction grating area are axisymmetric in a plane in which the lens unit lies.

According to some embodiments of the first aspect of the present invention, 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 have the same groove line structure.

According to some embodiments of the first aspect of the present invention, the lens unit is a see-through optical waveguide lens unit.

According to some embodiments of the first aspect of the present invention, a incoupling and turning region for incident light is provided on the first optical plane and/or on the second optical plane of the substrate.

According to a second aspect of the invention, an AR device is proposed, comprising at least one said lens unit. According to some embodiments of the second aspect of the present invention, the AR device is AR glasses.

Drawings

The technical solution of the present invention will be described in further detail with reference to the accompanying drawings and examples. In the drawings, like reference numerals are used to refer to like parts unless otherwise specified. Wherein:

FIG. 1 is a schematic structural view of a lens unit through which image light from a micro projector is transmitted to a person's eye, according to some embodiments of the present invention;

FIG. 2 is a schematic diagram of the diffractive transmission of incident light rays within a lens unit according to some embodiments of the invention;

FIGS. 3 (a) - (d) show schematic diagrams of the optical paths at the grating interface at different diffraction transmission stages, respectively;

FIG. 4 is a perspective view of a diffractive transmission process within a waveguide sheet, for example, with four grating modulations;

FIG. 5 shows a grating vector k plot of the diffraction propagation process within a waveguide slab;

FIG. 6 is a schematic illustration of a groove line structure of a grating region according to some embodiments of the present invention;

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

FIG. 8 is a schematic structural view of the coupling-in and inflection regions and the coupling-out region of a lens unit according to some embodiments of the present invention, where the coupling-in and inflection regions are disposed in one of the optical planes, where the coupling-in and inflection regions are completely surrounded by the corresponding coupling-out region;

FIG. 9 is a schematic structural view of the coupling-in and inflection regions and the coupling-out region of a lens unit where a coupling-in and inflection region are respectively provided in the first and second optical planes of the lens unit where the coupling-in and inflection regions are respectively completely surrounded by the corresponding coupling-out region according to some embodiments of the present invention;

FIG. 10 is a schematic structural view of the coupling-in and inflection regions and the coupling-out region of a lens unit according to some embodiments of the present invention, where the coupling-in and inflection regions are respectively connected to corresponding coupling-out region portions;

FIG. 11 is a schematic diagram of the structure of the coupling-in and turning regions and the coupling-out region of a lens unit according to some embodiments of the present invention, where neither the coupling-in nor turning regions is connected to the corresponding coupling-out region;

fig. 12 is a schematic illustration of AR glasses according to some embodiments of the invention;

FIG. 13 is a schematic view of AR eyewear having a modified lens unit profile according to some embodiments of the present invention;

FIG. 14 is a schematic view of AR glasses according to some embodiments of the present invention, where a separate light guiding element is provided;

fig. 15 is a schematic view of AR glasses according to further embodiments of the present invention.

Detailed Description

The concept of the invention will be described in further detail below with reference to specific embodiments. It should be noted that the examples set forth herein are merely illustrative of the inventive concepts of the present invention and should not be construed as limiting the invention. The technical features of the lens unit and the AR device referred to herein can be combined or substituted at will within the framework of the inventive concept, without departing from natural laws or technical norms, and are within the scope of the inventive concept.

It is to be noted that the embodiments shown in the drawings are only for the purpose of illustration and description of the inventive concept in a concrete and tangible manner, and are not necessarily to scale nor constitute a limitation of the inventive concept in terms of their dimensional structure.

The terms of orientation, up, down, left, right, front, rear, front, back, top, bottom, vertical, horizontal, etc., referred to or may be referred to in this specification are defined relative to the configuration shown in the various drawings or the normal use condition of the product, and are relative terms, and thus may be changed correspondingly according to the position and the use condition of the product. Therefore, these and other directional terms should not be construed as limiting terms.

By the present disclosure, a lens unit is provided that includes a substrate formed of an optical waveguide material having a first optical plane, a second optical plane opposite the first optical plane. The lens unit further comprises a first diffraction grating area and a second diffraction grating area, wherein the diffraction grating area arranged on the first optical plane of the substrate forms the first diffraction grating area, and the diffraction grating area arranged on the second optical plane of the substrate opposite to the first optical plane forms the second diffraction grating area. The first diffraction grating region has a first uniform grating vector in a first optical plane of the substrate, and the second diffraction grating region has a second uniform grating vector in a second optical plane of the substrate opposite the first optical plane.

That is, according to the present invention, the diffraction grating regions on a first optical plane of the substrate all have the same grating vector, i.e., a first grating vector, and the diffraction grating regions on a second optical plane of the substrate opposite to the first optical plane all have the same grating vector, i.e., a second grating vector. Therefore, the lens unit (hereinafter also referred to as a waveguide plate) according to the present invention has two grating vectors in total, so that not only can emergent light and incident light be kept completely parallel, but also the product design freedom is high, the structure is simple, mass production processing is easy, and the present invention has a high industrial application value.

Fig. 1 is a schematic diagram of a lens unit through which image light emitted by the micro projector 40 is transmitted to a person's eye, according to some embodiments of the present invention. As shown in fig. 1, the lens unit comprises a substrate 1 made of an optical waveguide material, for example having a sheet or plate-like shape, and forming a total-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 may be optical glass or optical resin.

A first diffraction grating area 2 and a second diffraction grating area 3 are respectively arranged on a substrate 1 made of optical waveguide materials, wherein the first diffraction grating area 2 is arranged on a first optical plane of the substrate 1, and the second diffraction grating area 3 is arranged on a second optical plane of the substrate 1 opposite to the first optical plane. With this arrangement, a first diffraction grating region 2 provided on a first optical plane of the substrate 1 and a second diffraction grating region 3 provided on a second optical plane of the substrate 1 opposite the first optical plane are opposite to each other on both sides of the substrate 1 and preferably overlap at least partially, whereby light is diffractively propagated in the waveguide plate between two oppositely overlapping grating interfaces within the range of grating regions that overlap each other.

Furthermore, a first diffraction grating area 2, which is arranged in a first optical plane of the substrate 1, has a first grating vector, and a second diffraction grating area 3, which is arranged in a second optical plane of the substrate 1 opposite the first optical plane, has a second grating vector, wherein incident light is coupled out in the lens unit after at least four grating modulations. With such an optic unit or waveguide, a portion of the totally reflected light can be released by diffraction into the eye each time it encounters a grating on the surface of the substrate 1, and the remaining portion of the light continues to propagate in the waveguide until it next hits the grating on the surface of the waveguide.

In the embodiment shown, one diffraction grating active area, namely a first diffraction grating area 2 and a second diffraction grating area 3, is provided on each of the two opposite optical surfaces. Thus, after the image light emitted from the micro projector 40 is coupled into the lens unit, the image light is diffused, transmitted and coupled out after being totally reflected and diffracted for a plurality of times in the substrate 1 of the lens unit, and finally, the image can be seen in the diffraction grating working area.

FIG. 2 is a schematic diagram of a diffracted transmitted light path of an incident light ray within a lens unit according to some embodiments of the present invention. The diffractive transmission path of incident light within the lens unit according to some embodiments of the invention is described subsequently in conjunction with the schematic diagram of fig. 2. The image light is coupled into the lens unit at an angle to the surface of the waveguide plate, in particular substantially perpendicular to the surface of the waveguide plate, wherein the plane of one diffraction grating area is referred to as the upper surface and the plane of the other diffraction grating area is referred to as the lower surface. It should be noted that the orientation assumed herein is merely used to describe the diffractive transmission path in terms of aspects, and the principles and processes are equally applicable to other orientations and are within the scope of the disclosure and description of the present invention.

As shown in fig. 2, the image light a from the micro projector 40 is coupled into the lens unit at an angle to the waveguide sheet surface, in particular substantially perpendicular to the waveguide sheet surface. For example, when the diffraction grating overlap region is irradiated from the upper surface, light is diffracted by the lower surface grating, and a diffraction order in the b direction is generated. Meanwhile, through diffraction of the upper surface grating, diffraction orders towards the c direction are generated. Because the subsequent transmission of the b and c diffracted lights has high symmetry, the subsequent transmission is explained by taking the b diffracted light as an example.

As shown, the b-direction diffraction order is diffracted by the upper surface grating to generate d-direction diffraction order, and the zero-order diffraction light is transmitted to the b direction continuously. The d-direction diffraction light is diffracted by the lower surface to generate e-direction diffraction light, and the zero-order diffraction light is continuously transmitted to the d direction. The e-direction diffraction order light is diffracted by the upper surface and then coupled out partial light f, and the zero-order diffraction light is continuously transmitted to the e direction. The light f is partially coupled out towards the upper surface and its transmission direction is symmetrical to the incident light a about the normal of the waveguide plate. The other part of the light f is coupled out towards the lower surface and its transmission direction is identical to the incident light a.

Therefore, in some embodiments of the present invention, the incident light is coupled out of the waveguide after at least four grating modulations, during which the light propagation direction of the diffraction orders b, d, e is at an angle larger than the critical angle required for total reflection with respect to the normal of the surface of the waveguide, thus ensuring no loss during transmission inside the waveguide. During the propagation process, the zero-order diffracted light will continue to be transmitted by total internal reflection, for example, diffuse towards 3 directions b, d, e, and the diffusion is accompanied by diffraction coupling, for example, the zero-order diffracted light in the direction d is diffracted and coupled out again after being diffracted twice by g and h, and then, after the diffusion, light can be coupled out in the whole grating working area finally, so that the human eye can observe complete and continuous clear images at any position of the lens.

For clarity of explanation of the light diffraction transmission process of the lens unit according to the present invention, fig. 3 (a) - (d) show schematic diagrams of the light paths at the grating interface at different diffraction transmission stages, respectively.

Fig. 3 (a) - (b) show schematic diagrams of the first diffraction occurring on the first diffraction grating region and the second diffraction grating region, respectively, of the image light. As shown in FIG. 3 (a), when the incident light I is normally incident on the upper surface grating work area of the waveguide plate, the transmission diffraction order T is generated in the waveguide plate _-1 、T ₀ 、T ₁ Wherein T is ₁ I.e. the diffraction order in the c-direction. In fig. 3 (a), d denotes a pitch of the grating, i.e., a distance between adjacent grooves, h denotes a groove depth, and W denotes a protrusion width.

FIG. 3 (b) shows the transmission diffraction order T ₀ When the light is incident on the lower surface grating work area, R is generated _-1 、R ₀ 、R ₁ Three reflection diffraction orders, wherein R _-1 I.e. the diffraction order in the b direction.

Fig. 3 (c) shows a schematic diagram of an intermediate diffraction process performed in the waveguide sheet. In FIG. 3 (c)The upper area is a medium waveguide layer, and the lower area is air. The b-direction diffraction light is incident light I in the figure, which is incident on the upper surface diffraction grating working area at a spherical angle (theta, phi) to generate a reflection diffraction order R _-1 、R ₀ Wherein R is _-1 I.e. the diffraction order in the d-direction. The diffracted light in the d-direction is incident on the lower surface diffraction grating active area, and this process can be similarly represented by FIG. 3 (c), where R _-1 The diffraction order is in the e-direction. The diagram of fig. 3 (c) shows the second and third diffraction processes for the case where the image light is modulated four times, for example, at the grating interface.

Fig. 3 (d) shows a schematic diagram of the image light out of the waveguide sheet. For example, the e-direction diffraction order in fig. 2 is incident on the upper surface diffraction grating active area, and the diffraction process can be represented by fig. 3 (d). Now the transmitted diffraction order T is generated _-1 And reflection diffraction order R _-1 、R ₀ . The diagram of fig. 3 (d) shows a fourth diffraction process for the case where the image light is modulated, for example, four times at the grating interface.

Taking the example of four grating modulations as an example, fig. 4 shows a perspective view of the diffraction transmission process in the waveguide sheet. As shown in the figure, the image light is coupled into the waveguide sheet along, for example, a z-axis substantially perpendicular to the grating plane, after the first diffraction is performed on the grating regions of the upper surface and the lower surface of the waveguide sheet, respectively, i.e., the first grating modulation, the second and third modulation are performed on the waveguide sheet continuously through the diffraction and/or total reflection of the upper and lower grating interfaces, and finally the fourth diffraction on the grating interface is coupled out of the waveguide sheet. Obviously, the incident light of the coupling-in and turning region and the emergent light of the coupling-out region are symmetrical with respect to the normal of the surface of the waveguide sheet, so that the complete and distortion-free image is transmitted to human eyes.

It should be noted that, when the incident light ray coupled into the waveguide sheet and the emergent light ray coupled out of the waveguide sheet are on the same side of the waveguide sheet, the incident light ray and the emergent light ray are symmetrical with respect to the normal of the surface of the waveguide sheet. When the incident light of the coupling-in waveguide sheet and the emergent light of the coupling-out waveguide sheet are on different sides of the waveguide sheet, the directions of the incident light and the emergent light are kept consistent. In the embodiment of fig. 4, the incident ray a is incident perpendicular to the surface of the waveguide sheet, and the incident ray a and the emergent ray f are on the same side of the waveguide sheet. It should be noted that, in fig. 4, since the incident light ray a coupled into and turning region is incident perpendicularly to the surface of the waveguide sheet, the emergent light ray f symmetrical to the incident light ray a about the normal of the surface of the waveguide sheet is also kept perpendicular to the surface of the waveguide sheet, i.e. the emergent light ray f is kept parallel to the incident light ray a and in the opposite direction.

Since the diffraction process includes a plurality of diffraction orders, the grating can only retain the required diffraction orders through design, and the energy of other diffraction orders can be ignored, and the above description only takes zero order and first order diffraction as an example, but the principle and process are also applicable to other diffraction orders and processes in the spatial direction, and are not repeated herein.

Thus, in some embodiments according to the invention, the incident light is coupled out after at least four grating modulations in the lens unit, wherein a first diffraction grating area 2 provided on a first optical plane of the substrate 1 and a second diffraction grating area 3 provided on a second optical plane of the substrate 1 opposite to the first optical plane are each modulated at least twice. As will be described in detail below, the light is modulated by the grating, and the light is diffracted by the grating into zero-order diffraction light and first-order diffraction light, wherein the zero-order diffraction light does not change the component of the light wave vector in the plane of the waveguide plate, while the first-order diffraction light changes the light wave vector of the light, and the component of the light in the plane of the waveguide plate is also changed, that is, in each diffraction of the light, the first-order diffraction light is regarded as being modulated by the grating, while the zero-order light continues to propagate and is diffracted next time, and the zero-order diffraction light and the first-order diffraction light are both alternately incident on two grating regions of the waveguide plate to be diffracted, so that the two-dimensional diffusion of the coupled-in light is realized. It is understood that the first grating region and the second grating region can be designed to retain zero-order diffraction light and plus-minus one-order diffraction light, or other diffraction order light, which can be changed as required by those skilled in the art, but all fall within the technical solution of the present invention.

After the image light emitted by the micro projector 40 is coupled into the lens unit, the image light is expanded and coupled out in the spatial direction after being totally reflected and diffracted at least four times in the substrate 1 of the lens unit. In other words, a two-dimensional pupil expansion in at least two directions is simultaneously achieved by the corresponding light transmission process, so that, for example, the image light can be coupled out over the entire diffraction grating operating region.

It is noted that the grating vector is a characterizing parameter of a diffraction grating, which depends on the orientation of the grating and the spatial period of the grating. In particular, the orientation of the grating vector is perpendicular to the positive and negative directions of the grating groove lines, while the magnitude of the grating vector is denoted as k =2 pi/d, where d is the grating period.

The grating vector of the first diffraction grating region of the first optical plane of the lens unit or waveguide plate can be marked as two components k ₁ ＝(±D _1x ,±D _1y ) The grating vector of the second diffraction grating region of the second optical plane may be denoted as k ₂ ＝(±D _2x ,±D _2y )。

According to the invention, the grating period can be set to be proper, so that the image light can only generate 0-order and 1-order diffraction light in the process of transmission and diffusion of the waveguide piece.

The amplitude of the wave vector of the incident light can be expressed in wavenumbers: k is a radical of _r =2 pi/λ, where λ represents the wavelength of diffracted light. Which has a component k in two directions in the plane of the waveguide plate _rx And k _ry . The wave number in air can be labeled k _r0 The wavenumber can be expressed as k as it enters the medium _rn ＝k ₀ * n, where n is the refractive index of the material.

Incident light k _r0 The light wave vector of the 1 st order diffracted light diffracted by the first diffraction grating region of the first optical plane of the waveguide sheet can be represented as k _r1 The effect of the grating on its diffraction break can be described by the diffraction equation, and its vector form in the plane of the waveguide sheet can be expressed as:

(k _r1x ，k _r1y )＝(k _r0x +D _1x ，k _r0y +D _1y )

diffracted light k _r1 Received by the second diffraction grating region of the second optical plane to produce 1 st order diffraction, the resulting light wave vector can be represented as k _r2 The same principle is as follows:

(k _r2x ，k _r2y )＝(k _r1x +D _2x ，k _r1y +D _2y )

the first diffraction grating area of the first optical plane receives the diffracted light k again _r2 The resulting diffracted 1-order wave vector can be expressed as k _r3 The same principle is as follows:

(k _r3x ，k _r3y )＝(k _r2x +D _1’x ，k _r2y +D _1’y)

the second diffraction grating region of the second optical plane receives the diffracted light k _r3 The resulting diffracted 1-order wave vector can be expressed as k _r4 The same principle is as follows:

(k _r4x ，k _r4y )＝(k _r3x +D _2’x ，k _r3y +D _2’y )＝(k _r0x +D _1x +D _2x +D _1’x +D _2’x ，k _r0y +D _1y +D _2y +D _1’y +D _2’y )

the waveguide sheet must satisfy achromatic imaging conditions, that is, after image lights with different wavelengths are diffused and transmitted by the waveguide sheet and finally coupled out, the direction of emergent light is consistent with that of incident light. In other words, the incident light wave number (k) _r0x ，k _r0y ) And the number of emitted light waves (k) _r4x ，k _r4y ) Comprises the following steps:

(k _r0x ，k _r0y )＝(k _r4x ，k _r4y )

therefore, the grating vector of the waveguide sheet must satisfy:

D _1x +D _2x +D _1’x +D _2’x ＝D _1y +D _2y +D _1’y +D _2’y ＝0

due to the grating of the first optical plane area of the waveguide sheet there is a relationship:

D _1x ＝-D _1’x ，D _1y ＝-D _1’y

the grating of the second optical plane area has the relationship:

D _2x ＝-D _2’x ，D2y＝-D _2’y

therefore, the achromatic imaging condition (k) is necessarily satisfied _r0x ，k _r0y )＝(k _r4x ，k _r4y ). Due to the raster vector k ₁ And k ₂ Depending on the grating period, independent of the wavelength of the light, the grating vector satisfies this condition and any wavelength satisfies the achromatic imaging condition according to the solution proposed by the present invention.

Figure 5 shows a graph of the grating vector k for the diffractive transmission process. The image light emitted by the micro-projector 40 passes through the double diffraction-coupled waveguide plate in the grating overlapping region, for example, and the light turning effect generated by the double diffraction can be represented by the superposition of two coupled grating vectors: k is a radical of _incouple1 And k is _incouple2 . The coupled light is totally reflected for several times and is coupled out of the waveguide sheet by two (or more than two) times of decoupling diffraction, and the effect of the grating decoupling on the light turning can be represented by the superposition of two decoupling grating vectors: k is a radical of _decouple1 And k is _decouple2 . The sum of the four grating vectors is equal to zero or close to zero, i.e. below a certain threshold value, so that the angle of the light outcoupled from the final waveguide plate is substantially constant, i.e. mutually coincident with (or mutually negative with respect to) the light in-coupled, and the image is diffusely transmitted.

In the illustrated embodiment, this is present because the period on both grating faces remains constantThe relationship is as follows: | k _incouple1 |＝|k _decouple1 |，|k _incouple2 |＝|k _decouple2 I.e. the corresponding incoupling grating vector and decoupling grating vector on each grating surface are equal in size and opposite in direction. Therefore, the vector superposition graph just encloses a parallelogram, especially a rhombus, and the grating vector returns to the origin, so that the vector sum is ensured to be zero. By adopting the measures, the problem of image quality reduction caused by non-zero vector sum in the traditional process and waveguide slice structure is avoided, and the requirements on the design and manufacture of the lens unit are reduced.

In other embodiments, the grating vector k diagram may not be a diamond but a regular parallelogram, and in these schemes, the sum of the four grating vectors is still guaranteed to be zero, because the light will be diffracted twice by the same grating in the four diffractions in the waveguide sheet, i.e. the opposite sides in the grating vector k diagram are always parallel and equal in size (i.e. the in-coupling grating vector and the out-coupling grating vector), so the sum of the vectors must be zero. And further ensures the parallel of the incident light and the emergent light of the waveguide plate and ensures the image quality of the input human eyes.

In some embodiments, the diffraction grating is designed as a coupling element, which must ensure that the diffraction angle of the resulting target diffracted light is limited to the total reflection angle and the maximum transmission angle (θ) _max ) This limitation can be expressed by the following physical relationship:

wherein, | k _r I represents the amplitude of the target wave vector, n is the refractive index of the optical material, and lambda ₀ Is the center wavelength of the image light source. The left side of the inequality represents a lower limit value generated by the total reflection angle for limiting the light wave vector, and the right side represents an upper limit value generated by the maximum transmission angle of the waveguide sheet for limiting the light wave vector. In some embodiments, the maximum transmission angle θ _max And may be as high as 75.

Specifically, light wave vector | k _r I needs to be smaller than the outer circle radius in fig. 5, i.e., the upper limit value, and larger than the inner circle radius, i.e., the lower limit value, to ensure effective transmission. Thus, the end of the light wave vector needs to be within the annular shadow during transmission, returning to the origin if and only if coupled out. The outer radius is the refractive index n and the central wavelength lambda of the waveguide material ₀ And a maximum angle theta _max Is measured as a function of (c).

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

The one-dimensional surface relief grating can be a positive grating, a blazed grating, an inclined grating or a sinusoidal grating. The grating groove depth can be 40-500 nm.

In some embodiments of the present invention, a grating structure is disposed in each of the first diffraction grating region 2 and the second diffraction grating region 3 of the waveguide sheet, and light is output to the human eye after being subjected to at least four grating modulations in the waveguide sheet, where the two grating structures respectively perform at least two modulations on the light, such as a vector superposition in a parallelogram shape in a light wave k diagram shown in fig. 5. In the vector superposition diagram shown in fig. 5, the opposite sides of the parallelogram are of the same grating structure, so that the opposite sides can be ensured to be always parallel and have the same size, thereby ensuring that the superposition of the four grating vectors is necessarily zero, ensuring that the input light and the output light of the waveguide sheet are parallel, and improving the image quality of input human eyes. In other words, in the present invention, the light is modulated by the first diffraction grating region 2 and the second diffraction grating region 3 on the upper and lower surfaces for at least four times, and the output light and the input light are in the same direction, thereby ensuring the quality of the image input to human eyes.

Figure 6 is a schematic diagram of a groove line structure of grating region 6 according to some embodiments of the present invention. In the schematic diagram of fig. 6, the vertical direction is taken as the y-axis of the rectangular plane coordinate system, and the horizontal direction is taken as the x-axis of the rectangular plane coordinate system. In this case, the grating vectors of the first diffraction grating region 2 and of the second diffraction grating region 3 of the waveguide plate can be arranged in the plane of the waveguide plate in an axially symmetrical manner, in particular with respect to the vertical direction or the y-axis.

In some embodiments, the first and second

diffraction grating regions

2 and 3 may have the same grating periods T1 and T2, and/or the first and second

diffraction grating regions

2 and 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.

As shown in fig. 6, the solid lines indicate the grating groove lines of the first diffraction grating region 2, and the broken lines indicate the grating groove lines of the second diffraction grating region 3. For example, the grating groove lines of two linear diffraction grating regions may form an acute angle θ, in particular the angle θ may be in the range of 40 ° to 90 °, in particular 60 °. Thus, assuming that one of the diffraction grating regions is flipped 180 ° around the x-axis or the y-axis, the grating structure of this flipped diffraction grating region should overlap or at least partly overlap the grating structure of the other diffraction grating region.

The grating structures in the diffraction grating regions are completely symmetrically overlapped or at least partially symmetrically overlapped about the xy plane, so that the same mold or process can be used for manufacturing the grating structures in the first diffraction grating region 2 and the second diffraction grating region 3, the imprinting mold for manufacturing the grating is simplified, the process is simplified, the production cost is reduced, and meanwhile, the mass production with stable quality is easy to realize. Meanwhile, because only two grating vectors can be arranged, the invention has higher process design freedom degree, simple structure and easy and stable mass production processing, thereby having higher industrial application value.

It is noted that according to some embodiments of the present invention, the first diffraction grating area 2 provided on a first optical plane of the substrate 1 may be a continuous area, and/or the second diffraction grating area 3 provided on a second optical plane of the substrate 1 opposite to the first optical plane may also be a continuous area. That is, the diffraction grating regions on each optical plane form an integral region without interruption regions.

In this case, for example, it is also possible to choose the diffraction grating area to be continuous over the entire optical plane, i.e. to cover the entire optical plane continuously, and to have a uniform grating vector for the grating areas in the same optical plane. For example, the first diffraction grating area 2 has a uniform first grating vector over the entire first optical plane of the substrate 1 and is continuous, i.e. continuously covers the entire first optical plane, and/or the second diffraction grating area 3 has a uniform second grating vector over the entire second optical plane of the substrate 1 and is continuous, i.e. continuously covers the entire second optical plane.

According to further embodiments of the present invention, the first diffraction grating area 2 provided on a first optical plane of the substrate 1 may also be a non-continuous area, and/or the second diffraction grating area 3 provided on a second optical plane of the substrate 1 opposite to the first optical plane may be a non-continuous area. That is, the diffraction grating region on a particular optical plane may be configured as a plurality of separate grating regions between which there is a substrate region where no grating structure is disposed. According to the invention, the plurality of separate grating regions lying on the first optical plane all have a uniform first grating vector, and the plurality of separate grating regions lying on the second optical plane all have a uniform second grating vector.

Of course, 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 may be respectively configured to be continuous and/or discontinuous, that is, the diffraction grating regions may be combined in any form of continuous or discontinuous structures on the optical planes on both sides of the substrate, according to the product design requirements and the photoelectric performance requirements.

Fig. 7 (a) - (d) are schematic diagrams of grating types according to some embodiments of the present invention. The diffraction grating according to the invention is an optical element with a periodic structure, which can be peaks and valleys embossed from the surface of the material, i.e. a Surface Relief Grating (SRG), or "bright-dark interference fringes" formed by the holographic technique by exposure inside the material, i.e. a holographic volume grating (VHG), both of which ultimately cause a periodic variation in the refractive index n.

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 fig. 7 (a) - (d), respectively. For example, a tilted grating or a triangular blazed grating, can maximize the optical coupling efficiency for diffraction toward the eye.

It should be noted that the diffraction angle of each diffraction order is determined by the incident angle of the light, the period of the grating, the groove angle in the groove direction, etc., and the diffraction efficiency of a certain diffraction order (i.e. a certain direction) can be optimized to the highest by designing other parameters of the grating, including but not limited to the refractive index n of the material, the shape of the grating, the thickness, the duty cycle, etc., so that most of the light propagates in this direction after diffraction. Therefore, by properly designing the grating structure and the light path, the optimal FOV, light efficiency, image definition and the like can be simultaneously realized by utilizing the technical scheme provided by the invention.

In addition, the single-side coupling-out grating of the waveguide sheet can be subjected to modulation of groove depth, duty ratio or shape, and the double-side coupling-out grating of the waveguide sheet can also be modulated, so that the uniformity of the coupling-out intensity in each area is better.

By the present disclosure, there is also provided a lens unit comprising a substrate of optical waveguide material having a first optical plane, a second optical plane opposite the first optical plane. The lens unit further comprises a first diffraction grating area and a second diffraction grating area, wherein the diffraction grating area arranged on the first optical plane of the substrate forms the first diffraction grating area, and the diffraction grating area arranged on the second optical plane of the substrate opposite to the first optical plane forms the second diffraction grating area. In this case, an incoupling and deflecting region for incident light is provided on the first optical plane of the substrate, wherein the incoupling and deflecting region provided on the first optical plane of the substrate and the outcoupling region provided on the first optical plane of the substrate have a uniform grating vector. In some variants, it is also possible additionally or alternatively to provide an incoupling and deflecting region for incident light on the second optical plane of the substrate, wherein the incoupling and deflecting region provided on the second optical plane of the substrate has a uniform grating vector with the outcoupling region provided on the second optical plane of the substrate.

In some variants, the portion of the diffraction grating area outside the coupling-in and turning area constitutes a coupling-out area for light out of the lens unit. Thus, a first diffraction grating region on a first optical plane of the substrate consists of the in-and turn regions and the out-coupling region on the first optical plane, and/or a second diffraction grating region on a second optical plane of the substrate opposite the first optical plane consists of the in-and turn regions and the out-coupling region on the second optical plane.

Thereby, a coupling-in and turning region for coupling-in and turning-over of image light and a coupling-out region for coupling-out of image light can be arbitrarily provided in the substrate 1 of the lens unit or waveguide, wherein for the proposed lens unit, the coupling-in and turning region can be provided in an arbitrary manner and shape according to optical design and structural design requirements, and the remaining portions of the first diffraction grating region 2 and the second diffraction grating region 3 outside the coupling-in and turning region are used as coupling-out regions.

In other words, fixed coupling-in and turning areas can be provided on the substrate 1 of the lens unit, while the remaining diffraction grating area serves as coupling-out area. The coupling-in and deflecting region serves to couple image light into the lens element or waveguide on the one hand and to deflect the image light into the desired design propagation direction after modulation by the coupling-in and deflecting region on the other hand.

Fig. 8 is a schematic structural view of the coupling-in and inflection regions and the coupling-out region of a lens unit according to some embodiments of the present invention, where the coupling-in and inflection regions a are disposed in only one of the optical planes. In the embodiment of fig. 8, for example, the first diffraction grating area of the lens unit includes an incoupling and turning area, as shown by the area a enclosed by the solid lines, and the only incoupling and turning area a is closely connected with and completely enclosed by the outcoupling area b of the optical plane. In fact, outside the coupling-in and turning region a, the remaining working area of the diffraction grating may be used as the whole coupling-out region for the outgoing light rays for gradually ejecting the image light rays out of the waveguide sheet into the human eye during diffraction. In this embodiment, since the in-coupling and turning area a is provided only in the first diffraction grating area of the lens unit, the out-coupling area may include a portion of the first diffraction grating area outside the in-coupling and turning area a and the entire second diffraction grating area at the opposite side.

Since the portions of the diffraction grating region outside the coupling-in and turning regions a can be used as coupling-out regions, and the coupling-in and turning regions a are completely surrounded by the coupling-out regions b on the optical plane, no total reflection surface exists between the coupling-in and turning regions and the coupling-out regions included in the diffraction grating region in the embodiment, and phase shift caused by the light beam striking the boundary between the grating structure and the total reflection surface can be avoided, so that the light in the embodiment does not generate phase jump in the propagation process, and the embodiment has the advantage of higher image definition compared with the conventional waveguide plate.

In the exemplary embodiment shown, a coupling-in and deflecting region for incident light is arranged in a first optical plane of the substrate 1, wherein this coupling-in and deflecting region arranged in the first optical plane of the substrate 1 has the same or identical grating vector as the coupling-out region in the first optical plane of the substrate 1. In addition or alternatively, an incoupling and return region for incident light can also be provided on the second optical plane of the substrate 1, wherein the incoupling and return region provided on the second optical plane of the substrate 1 has a uniform grating vector with an outcoupling region lying on the second optical plane of the substrate 1.

It is considered that the first and second diffraction regions that the incident light undergoes are set as the incoupling and inflection regions as shown by region a in fig. 8, and the portion of the outcoupling region that is in the same optical plane is shown by region b in fig. 8 (excluding region a).

In some embodiments, the gratings of the coupling-in and turning regions and the coupling-out region portion in the optical plane may have the same groove depth and duty cycle, so that the process may be simplified during the grating fabrication process, but still achieve satisfactory optical performance. In addition, in some variations, the grating groove depth and the duty ratio of the coupling-in and turning region may be greater than those of the coupling-out region located at the periphery thereof, and thus, the coupling-in efficiency, the angle of view, and the like of the light source may be increased. The arrangement of the grating groove depth and the change of the duty ratio can effectively increase the coupling-in efficiency of the light source, increase the light energy utilization rate and enlarge the coupling-in field angle. Note that adjustment of the grating groove depth and duty cycle does not change the grating vector, but affects diffraction efficiency. The groove depth and duty cycle relationships of the gratings of the coupling-in and turning-over regions and the coupling-out region in the optical plane described here also apply to the following embodiments presented in this application.

By the scheme provided by the invention, any diffraction grating area can be set as the coupling-in and turning area, and the rest of the diffraction grating area can be used as the coupling-out area. For example, the grating groove depth of the incoupling and turning regions may be 150-600 nm, while the grating period and grating orientation may coincide with the outcoupling region in the optical plane.

Fig. 9 is a schematic structural view of the coupling-in and inflection regions and the coupling-out region of the lens unit according to some embodiments of the present invention, where one coupling-in and inflection region is provided in the first and second diffraction grating regions of the lens unit, respectively. In this embodiment, since the portions of the diffraction grating region 6 outside the coupling-in and turning regions can be used as the coupling-out regions, the coupling-in and turning regions on both sides of the waveguide piece are completely surrounded by the corresponding coupling-out regions b, respectively. The main difference compared to the embodiment of fig. 8 is that an in-coupling and turning region for the incident light is additionally provided on the second optical plane of the substrate 1, wherein this in-coupling and turning region provided on the second optical plane of the substrate 1 and the out-coupling region at the second optical plane of the substrate 1 have a uniform grating vector.

The coupling-in and inflection regions may be present in both the first and second diffraction grating regions. There is an intersection where the incoupling and turning regions of the two faces can overlap, i.e. in the plane of the lens unit, the incoupling and turning region provided on the first optical plane of the substrate 1 has an at least partially overlapping region with the incoupling and turning region provided on the second optical plane of said substrate 1, as shown in fig. 9. In fig. 9, a hatched area c indicates a superimposed area, an area d indicates a remaining area of the first optical plane after the coupling-in and turning area of the first optical plane removes the superimposed area, and an area e indicates a remaining area of the second optical plane after the coupling-in and turning area of the second optical plane removes the superimposed area.

Here, for example, the overlapping region c can be used as the coupling-in region of the incident light, and the regions d and e can be used as the turning regions of the light. That is, the coupling-in and turning region includes a coupling-in region c and turning regions d, e. The coupling-in area c may be circular as shown, or may be triangular, rectangular, or elliptical. The turning regions d and e may have the shapes shown in the drawings, or may be any polygonal shapes. In some variations, the coupling-in and turning region profiles of the waveguide sheet on the two surfaces may have mirror symmetry, that is, after the waveguide sheet is turned 180 ° up and down around the x axis or the y axis, the grating regions 6 on the two surfaces are completely overlapped, so that the manufacturing mold can be saved, and the preparation and processing are facilitated. Of course, the coupling-in and turning region profiles and/or positions of the waveguide sheet on the two surfaces can be completely consistent according to the design and performance requirements.

In this embodiment, since the portions 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 region in the optical plane, no total reflection surface exists between the coupling-in and turning regions and the coupling-out region included in the diffraction grating region, and a phase shift caused by the light beam striking the boundary between the grating structure and the total reflection surface can be avoided, so that the light in this embodiment does not generate a phase jump during propagation, and has an advantage of higher image definition compared with a conventional waveguide plate.

Fig. 10 is a schematic structural view of the coupling-in and inflection regions and the coupling-out region of the lens unit according to some embodiments of the present invention, where the coupling-in and inflection regions are respectively connected to corresponding coupling-out region portions. In this embodiment, the coupling-in and turning regions on both sides of the waveguide sheet are only partially connected to the corresponding coupling-out region b in the optical plane, as shown, rather than being completely surrounded by the coupling-out region b.

Fig. 11 is a schematic structural view of the coupling-in and turning regions and the coupling-out region of the lens unit according to some embodiments of the present invention, where the coupling-in and turning regions are completely outside the coupling-out region in the optical plane, i.e. 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 regions on both sides of the waveguide sheet can be used as the coupling-out regions b. In this case, both 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 configured to be discontinuous or intermittent and divided into the coupling-in and turning regions and the coupling-out region, respectively.

As shown in fig. 11, the coupling-in and turning regions are not directly connected to or adjacent to the coupling-out region of the optical plane, but are separated from each other. Although the grating structures of the coupling-in and the turning region and the grating structures of the coupling-out region in the optical plane form regions that are separate from one another, all grating structures in the same optical plane still have identical or identical grating vectors.

According to some embodiments of the present invention, the outcoupling region b may be provided as a uniform grating, i.e. e.g. with a uniform groove depth and duty cycle, if the uniformity is not high for the outcoupling pupil. If there is a high uniformity requirement for the outcoupling pupil, the outcoupling region can be provided as a varying grating, i.e. the grating groove depth and the duty cycle are larger, for example, the farther the outcoupling region b is from the incoupling region c. Furthermore, the single-side coupling-out grating can be subjected to modulation of groove depth, duty ratio or tooth shape, and two coupling-out grating surfaces can be modulated, so that the uniformity of the light coupling-out intensity in each area is good.

In addition to the embodiments shown in fig. 8 to 11, for example, one or more coupling-in and turning regions may be provided on each optical plane, respectively, and here, the coupling-in and turning regions on both sides of the waveguide sheet may be arranged in mirror symmetry or in axial symmetry in the plane of the waveguide sheet. In some variants, one or more, in particular both, coupling-in and transition regions can also be provided on one optical plane, while the other optical plane is not provided with a coupling-in and transition region.

The relative position of the coupling-in and transition region with respect to the coupling-out region in the optical plane can also be varied according to the invention, for example the coupling-in and transition region can be located completely in the coupling-out region, partially connected to the coupling-out region or completely separated from the coupling-out region. In other words, since the portions of the diffraction grating regions outside the coupling-in and turning regions can be used as the coupling-out regions, the coupling-in and turning regions c, d, e can be included in, semi-included in, or separated from the grating coupling-out region b.

According to the present invention, the coupling-in and turning region provided on the first optical plane of the substrate 1 and the coupling-in and turning region provided on the second optical plane of the substrate 1 preferably have partial regions that overlap each other correspondingly, as viewed in a direction perpendicular to the plane of the waveguide sheet. That is, although the incoupling and turning regions are located on both sides of the waveguide sheet, respectively, the projections of these incoupling and turning regions in the plane of the waveguide sheet may have overlapping regions.

Furthermore, the first diffraction grating area 2 provided on a first optical plane of the substrate 1 may be configured as a continuous area, and/or the second diffraction grating area 3 provided on a second optical plane of the substrate 1 opposite to the first optical plane may also be configured as a continuous area. In this case, the corresponding coupling-in and turning regions may be completely or partly comprised in the corresponding coupling-out region, i.e. be part of the overall grating structure.

It should be further noted that 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 may have the same or different structures and shapes, and the coupling-in and turning-over regions and the coupling-out region disposed on both sides of the substrate 1 may also have the same or different structures and shapes, and the specific arrangement, structure, shape, optical parameters, etc. thereof may be adjusted and adopted in different combinations according to specific design and performance requirements, which are all within the scope of the present disclosure.

By the technical scheme provided by the invention, the design and processing difficulty of the lens unit and the AR equipment can be obviously simplified, so that the structure of the waveguide sheet can flexibly and reliably match the optical performance requirement and the mechanical structure requirement, and the dual requirements of product performance and manufacturing cost are met.

The lens unit provided by the invention can be flexibly applied to various different reality augmentation devices (AR devices), such as AR glasses, head-up displays and other wearable electronic devices.

According to the present invention, there is also proposed an AR apparatus, in particular AR glasses, which includes, for example, a frame for mounting lens units, temples for wearing the AR glasses, left and right lens units mounted in the frame, a calculation unit for data processing and generating image signals, and a micro projector that outputs an image based on the image signals generated by the calculation unit.

By means of the solution proposed by the invention, it is possible to realize an arbitrary arrangement of the coupling-in and turning regions on the optical plane of the substrate of the lens unit. The following takes AR glasses as an example, and an AR device using the lens unit is exemplarily described in detail.

Fig. 12 is a schematic diagram of AR glasses, where the AR device is AR glasses, according to some embodiments of the invention.

As shown, the AR glasses include a frame 60 for mounting the lens units, temples 90 for wearing the AR glasses, and left and

right lens units

10 and 20 mounted in the frame 60. Here, the temples 90 may be connected to the frame 60 in any manner, for example, in a flexible manner, or in a folded form, thereby forming a main body portion of the AR glasses. The electronics and optics of the AR glasses may optionally be mounted on the temple 90 and/or the frame 60 or embedded/buried in the material thereof. The 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 micro projector 40 outputting images based on the image signals generated by the computing unit 50, a micro display, a spatial sensor, a position sensor, and the like.

The lens unit (optical waveguide sheet) is a display member in the AR device. In the embodiment shown in fig. 12, the AR glasses include a left lens unit 10 (left eye optical waveguide display system) and a right lens unit 20 (right eye optical waveguide display system), wherein the camera 30 may be disposed at a midpoint position between the left lens unit 10 and the right lens unit 20, that is, at a midpoint position substantially above the bridge of the nose. The micro projector 40 and the calculation unit 50 are provided in the temple 90, for example.

It should be noted that the AR glasses include optical components and electronic components that can be flexibly selected according to design requirements and arbitrarily arranged according to structural conditions, and are not limited to the forms given by way of example. For example, the left lens unit 10 and the right lens unit 20 may be constructed as two separate lens units or may be two integral parts of one unitary lens unit. In the example of fig. 12, the camera 30 is provided at the midpoint between the left lens unit 10 and the right lens unit 20, but it is also conceivable to provide other suitable optical components and electronic components at this position, which will be described in detail in the following embodiments.

In operation, the micro-display in the micro-projector 40 displays an image, which is input through the projection lens to the in-coupling and turning region of the optical waveguide lens, and then is transmitted through the series of lights into the human eye. The computing unit 50 may not only provide image signals to the microdisplay, but may also communicate with other components in the system, such as the camera 30, spatial sensors, position sensors, micro projector 40, etc.

Micro-displays that may be used herein include, but are not limited to, digital Light Processors (DLPs), liquid crystal on silicon (LCoS), organic Light Emitting Diodes (OLEDs), and Micro light emitting diodes (Micro LEDs). The optical waveguide lens has a high transmittance to allow a user to clearly view the real world.

The camera 30 and the spatial sensor may 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 acquire environment pictures in a real scene, the eyeball tracking sensor can realize the eyeball tracking function, and the depth camera can acquire depth information of the scene, realize the functions of face and gesture recognition and the like.

The position sensor may be a combination of an accelerometer, a gyroscope, a magnetometer, and a global positioning system receiver. After the computing unit 50 processes the signals from the position sensors, the virtual picture can be more accurately superimposed in the real environment.

Fig. 13 is a schematic view of AR glasses according to some embodiments of the invention, with a modified glasses profile. As shown in fig. 13, the AR glasses include a frame 60 for mounting the lens units and temples 90 for wearing the AR glasses, and left and

right lens units

10 and 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, respectively mounted in the frame 60.

The difference from the embodiment shown in fig. 12 is that in the embodiment shown in fig. 13, the lens units mounted in the frame 60 are subjected to chamfering. That is to say, the lens unit has a corner cut shape at least one of its right angles, for example on the basis of a rectangular basic shape. Accordingly, the frame 60 of the AR glasses may also adopt a chamfered shape matching the chamfered shape of the lens unit. For example, the waveguide sheet is constructed into a square with unfilled corners, so that the shape of the waveguide sheet turning region is matched, the size of the AR glasses can be reduced, the structural space requirements of different components can be matched, and more flexible and variable product design models can be adopted. Of course, the waveguide plate can also be designed in any other shape with missing or chamfered corners, for example rectangular and polygonal.

In some modifications, the frame 60 may not be provided with a chamfered shape, but the frame 60 may leave a mounting space for components at a portion corresponding to the chamfered shape of the lens unit, whereby electronic components or other devices may be provided at the chamfered portion of the lens unit of the frame.

Fig. 14 is a schematic view of AR glasses according to some embodiments of the invention. As shown in fig. 14, the overall structure of the AR eyeglasses is similar to that of the previous embodiment, and the AR eyeglasses include a frame 60 for mounting lens units, temples 90 for wearing the AR eyeglasses, and left and

right lens units

10 and 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 one integral lens unit. In other words, the left lens unit 10 and the right lens unit 20 are formed of different components of one unique lens unit, respectively. Therefore, the substrate 1 of the optical waveguide material of the left lens unit 10 and the right lens unit 20 is continuous and integral.

For this purpose, a separate light guide element 70 may be provided which guides the image light of the micro projector 40 or micro display to the coupling-in and turning region 35 of the lens unit. With the light guide element 70 provided, the left lens unit 10 and the right lens unit 20 can share a single micro projector 40 or micro display. The coupling-in and turning region 35 may alternatively be arranged at the geometrical centre of the waveguide plate, for example on the axis of symmetry. The light guide element 70 is connected to the micro projector 40 at one end and to the coupling-in and turning region 35 of the lens unit at the other end, thereby transferring image light from the micro projector 40 or micro display to the lens unit.

In the illustrated embodiment, the coupling-in and hinge region 35 is disposed at a neutral position between the left lens unit 10 and the right lens unit 20, that is, at a neutral position substantially above the bridge of the nose, whereby a uniform and coordinated image transmission effect of the left lens unit 10 and the right lens unit 20 can be easily achieved. Meanwhile, components such as the computing unit 50, the micro projector 40 or the micro display of the display system can be arranged at appropriate positions of the AR device by using the appropriately shaped light guide element 70, for example, in the form of an optical fiber, so that the structural space is reasonably utilized, the design is flexible, and the image transmission and display quality is ensured. In the embodiment of fig. 14, the micro projector 40 and the calculation unit 50 are arranged on one of the temples 90, and the image light is transmitted from the micro projector 40 through the light guide element 70 to the coupling-in and turning region 35 of the lens unit, enters the lens unit through the coupling-in and turning region 35, and finally exits the human eye through the coupling-out region by means of total reflection and diffraction propagation.

Fig. 15 is a schematic view of AR glasses according to further embodiments of the present invention. In this embodiment, the possibility of arranging the optical components and the electronic components in different ways is given as an example. In the embodiment shown in fig. 12-11, the camera 30 is disposed at a central position between the left lens unit 10 and the right lens unit 20, i.e., at a central position approximately above the bridge of the nose. In contrast, in the embodiment of fig. 15, instead of the camera 30, the micro projector 40 or micro display may be disposed directly at a center position between the left lens unit 10 and the right lens unit 20, that is, at a center position approximately above the bridge of the nose. Thus, image light from the micro projector 40 or micro display can enter the lens unit directly through the incoupling and turning region, omitting the intermediate additional light guiding element 70.

Similarly, changes in the placement and manner of other optical and electronic components may also be considered, in conjunction with the particular shape and spatial structure of the AR device. For example, in the example of fig. 15, sensors 80, including position sensors and/or spatial sensors, etc., may be disposed in one or both of temples 90. Obviously, on the premise of meeting the structural and working requirements of optical components and electronic components of AR equipment, the shape of the structural lens unit can be changed, and the positions of different components and parts can be flexibly set.

It should be noted that the technical solutions proposed herein are not limited to the contents in the above description, and those skilled in the art can make various modifications and changes to the above embodiments without departing from the inventive idea of the present invention, and these modifications and changes all fall into the protection scope of the present invention.

Claims

A lens unit, comprising:

a substrate composed of an optical waveguide material having a first optical plane and a second optical plane opposite the first optical plane; and

a first diffraction grating region and a second diffraction grating region, wherein the diffraction grating region provided on a first optical plane of the substrate constitutes the first diffraction grating region, and the diffraction grating region provided on a second optical plane of the substrate opposite to the first optical plane constitutes the second diffraction grating region;

wherein the first diffraction grating region has a uniform first grating vector on a first optical plane of the substrate and the second diffraction grating region has a uniform second grating vector on a second optical plane of the substrate opposite the first optical plane.
The lens unit according to claim 1, wherein the first diffraction grating area provided on a first optical plane of the substrate is a continuous area and/or the second diffraction grating area provided on a second optical plane of the substrate opposite to the first optical plane is a continuous area.
The lens unit according to claim 2, wherein the first diffraction grating area is continuous over the entire first optical plane of the substrate and/or the second diffraction grating area is continuous over the entire second optical plane of the substrate.
The lens unit according to claim 1, wherein the first diffraction grating area provided on a first optical plane of the substrate is a non-continuous area and/or the second diffraction grating area provided on a second optical plane of the substrate opposite to the first optical plane is a non-continuous area.
The lens unit of any one of claims 1 to 4, wherein a first grating vector of the first diffraction grating area is different from a second grating vector of the second diffraction grating area.
The lens unit of any one of claims 1 to 5, wherein incident light is coupled out within the lens unit after at least four grating modulations.
The lens unit according to any one of claims 1 to 6, wherein a first diffraction grating area provided on a first optical plane of the substrate and a second diffraction grating area provided on a second optical plane of the substrate opposite to the first optical plane modulate incident light at least twice, respectively.
The lens unit according to any one of claims 1 to 7, wherein a first diffraction grating area provided on a first optical plane of the substrate and a second diffraction grating area provided on a second optical plane of the substrate opposite to the first optical plane have the same grating period.
The lens unit according to any one of claims 1 to 8, wherein the grating groove lines of the first diffraction grating area and the grating groove lines of the second diffraction grating area have an angle of 40 to 90 ° in the plane of the lens unit.
The lens unit of claim 9, wherein the grating groove lines of the first diffraction grating region have an angle of 60 ° with the grating groove lines of the second diffraction grating region.
The lens unit according to any one of claims 1 to 10, wherein, in the diffraction propagation process of the lens unit, the diffraction angle of the diffracted light satisfies the formula:

in the formula | k _r I represents the amplitude of the target light wave vector, n is the refractive index of the optical waveguide material, and λ ₀ Is the central wavelength, θ, of the image light source _max Representing the maximum transmission angle.
The lens unit according to any one of claims 1 to 11, wherein the optical waveguide material constituting the substrate is optical glass or optical resin.
The lens unit according to any one of claims 1 to 12, wherein a first diffraction grating area provided on a first optical plane of the substrate and a second diffraction grating area provided on a second optical plane of the substrate opposite to the first optical plane comprise surface relief gratings.
The lens unit according to claim 13, wherein the first diffraction grating area provided on the first optical plane of the substrate and the second diffraction grating area provided on the second optical plane of the substrate opposite to the first optical plane comprise a positive grating, a blazed grating, a tilted grating and/or a sinusoidal grating.
The lens unit according to any one of claims 1 to 14, wherein a first diffraction grating area provided on a first optical plane of the substrate and a second diffraction grating area provided 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 opposite to each other.
The lens unit according to any one of claims 1 to 15, wherein the grating vector of the first diffraction grating area and the grating vector of the second diffraction grating area are axisymmetric in the plane of the lens unit.
The lens unit according to any one of claims 1 to 15, wherein a first diffraction grating area provided on a first optical plane of the substrate and a second diffraction grating area provided on a second optical plane of the substrate opposite to the first optical plane have the same groove line structure.
The lens unit according to claim 16, wherein a first diffraction grating area provided on a first optical plane of the substrate and a second diffraction grating area provided on a second optical plane of the substrate opposite to the first optical plane have the same groove line structure.
The lens unit of any one of claims 1 to 18, wherein the lens unit is a see-through optical waveguide lens unit.
The lens unit according to any one of claims 1 to 19, wherein a coupling-in and turning region for incident light is provided on a first optical plane and/or on a second optical plane of the substrate.
An AR device comprising at least one lens unit of any one of claims 1-20.
The AR device of claim 21, wherein the AR device is AR glasses.