Patent Description:
An augmented reality (AR) near-to-eye display technology is a wearable display system that enables a human eye to see an external real scene, and also to see a virtual scene generated by a computer through a certain optical system. In the augmented reality system, a computing component analyzes and processes the real scene observed by a user, and then generated virtual enhancement information is superimposed into the real scene through the near-to-eye display technology, so as to realize a seamless integration of the real scene and the virtual scene, thus assisting the user in recognizing the real world deeply and comprehensively. The AR apparatus has been applied in many fields, including military, navigation, education, medical treatment, industry and so on, and has broad applications in the field of electronic consumption. As one of the core technologies of the AR apparatus, the near-to-eye display technology has also become a research hotspot in industry and academia.

<CIT> discloses an eyepiece waveguide for an augmented reality display system, which includes an optically transmissive substrate, an input coupling grating region, a multi-directional pupil expander region, and an exit pupil expander region. The input coupling grating region receives an input beam of light and couples the input beam into the substrate as a guided beam. The multi-directional pupil expander region is positioned to receive the guided beam from the input coupling grating region and to diffract it in a plurality of directions to create a plurality of diffracted beams. The exit pupil expander region is positioned to receive one or more of the diffracted beams and to out couple them from the optically transmissive substrate as output beams.

<CIT> discloses an optical component, in which a combination of diffractive beam splitting and total internal reflection within the optical component results in multiple versions of each input beam being outwardly diffracted from an exit surface relief grating along both the width and the height of an exit zone as output beams in respective outward directions that substantially match the respective inward direction of the corresponding input beam.

<CIT> discloses a waveguide display, in which a flexible border for a liquid lens serves as a transition to allow movement at an edge of a membrane that is part of the liquid lens. The flexible border allows vertical translation of an end of a membrane portion.

The present invention provides a waveguide display device and an augmented reality display apparatus. The waveguide display device has a large range of an exit pupil, a small volume and a light weight, which is conducive to a miniaturization design of products. The technical solutions of the present invention are shown as follows.

Embodiments of a first aspect of the present invention provide a waveguide display device. The waveguide display device includes a waveguide substrate and a first optical element, a second optical element and a third optical element coupled to the waveguide substrate. The first optical element is located on a first side of the waveguide substrate. The first optical element is adjacent to a first surface of the waveguide substrate and configured to couple an incident light into the waveguide substrate, and the first surface of the waveguide substrate is a surface of the waveguide substrate facing away from a human eye. The waveguide substrate is configured to couple the light coupled-in by the first optical element to the second optical element. The second optical element and the third optical element are located on a second side of the waveguide substrate. The second optical element is adjacent to a second surface of the waveguide substrate and is configured to couple the light coupled to it by the waveguide substrate to the third optical element in a first direction and a second direction when viewed in a direction perpendicular to a plane where the third optical element is located. The second surface of the waveguide substrate is a surface of the waveguide substrate facing the human eye. The third optical element is adjacent to the first surface of the waveguide substrate and is configured to couple the light coupled to it by the second optical element to the second optical element in the first direction or the second direction when viewed in the direction perpendicular to the plane where the third optical element is located, and to couple the light coupled to it by the second optical element out to the human eye. The light coupled to the second optical element continues to propagate many times between the second optical element and the third optical element in the first direction or the second direction.

Optionally, the second optical element is configured to couple the light coupled to it by the waveguide substrate to the third optical element in the first direction by total reflection, and to couple the light coupled to it by the waveguide substrate to the third optical element in the second direction by diffraction.

Optionally, the third optical element is configured to couple the light coupled to it by the second optical element to the second optical element in the first direction or the second direction by total reflection, and to couple the light coupled to it by the second optical element out to the human eye by diffraction.

Optionally, the waveguide substrate is configured to couple the light coupled-in by the first optical element to the second optical element after the light coupled-in by the first optical element goes through at least one total reflection inside the waveguide substrate.

Optionally, the second optical element and the third optical element are opposite to each other, and an area of the second optical element and an area of the third optical element are equal.

Optionally, the third optical element is configured to couple the light coupled to it by the second optical element out to the human eye in the direction perpendicular to the plane where the third optical element is located.

Optionally, the first direction is perpendicular to the second direction.

Optionally, the second optical element and the third optical element are parallel to each other.

Optionally, the first optical element covers at least a part of the first surface of the waveguide substrate.

Optionally, the second optical element covers at least a part of the second surface of the waveguide substrate, the third optical element covers at least a part of the first surface of the waveguide substrate, and the second optical element is opposite to the third optical element.

Optionally, the first optical element is a one-dimensional grating, and the second optical element and the third optical element are two-dimensional gratings.

Optionally, the first optical element and the third optical element are on the first surface of the waveguide substrate and spaced apart from each other, and the second optical element is on the second surface of the waveguide substrate and opposite to the third optical element.

Embodiments of a second aspect of the present invention provide an augmented reality display apparatus. The augmented reality display apparatus includes a waveguide display device according to any one of the above embodiments and an optical machine configured to emit a light to the first optical element.

Optionally, the augmented reality display apparatus includes one of AR glasses, an AR head-mounted display apparatus and a head-up display apparatus.

The technical solutions according to the embodiments of the present invention bring at least the following beneficial effects.

In the embodiments of the present invention, the waveguide display device includes the waveguide substrate and the first optical element, the second optical element and the third optical element on the waveguide substrate. The first optical element is configured to couple the incident light into the waveguide substrate. The waveguide substrate is configured to couple the light coupled-in by the first optical element to the second optical element. The second optical element is configured to couple the light coupled to it by the waveguide substrate to the third optical element in the first direction and the second direction when viewed in the direction perpendicular to a plane where the third optical element is located. The third optical element is configured to couple the light coupled to it by the second optical element to the second optical element in the first direction or the second direction when viewed in the direction perpendicular to a plane where the third optical element is located, and to couple the light coupled to it by the second optical element out to the human eye. The second optical element and the third optical element are arranged at the first and second surfaces of the waveguide substrate, respectively. A relay optical element is omitted, thus reducing a volume and a weight of the waveguide display device. Moreover, the light coupled to the second optical element continues to propagate many times between the second optical element and the third optical element along the first direction or the second direction, so as to realize a two-dimensional mydriasis.

It should be understood that the above general description and the following detailed description are only exemplary and explanatory and do not limit the present invention.

Accompanying drawings herein are incorporated into the specification and constitute a part of the specification. The accompanying drawings show embodiments consistent with the present invention, and together with the specification are used to explain the principle of the present invention. However, they do not constitute an improper limitation to the present invention.

In order to enable those ordinary skilled in the art to better understand the technical solutions of the present invention, the technical solutions in embodiments of the present invention will be clearly and completely described below in combination with the accompanying drawings.

It should be noted that the terms "first," "second" and the like in the descriptions, claims and the above accompanying drawings of the present invention are used to distinguish similar objects, and not necessary be used to describe a specific sequence or order. It should be understood that the terms used in this manner can be interchanged where appropriately so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. The implementations described in the following embodiments do not represent all possible implementations consistent with the present invention. On the contrary, they are only examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

A core task of AR near-to-eye display technology is for virtual and real superimposition, that is, to allow a light of the real world and a light of a virtual image to pass through and reach the human eye simultaneously. The near-to-eye display technology includes a geometrical optics superimposer technology and the near-to-eye display technology is based on diffractive optics.

At present, the near-to-eye display technology based on diffractive optics has a small range of an exit pupil, a volume of the apparatus is large, and a weight of the apparatus is relatively large.

Specifically a waveguide display device of the near-to-eye display technology based on diffractive optics includes: an in-coupling diffractive element, a relay diffractive element and an out-coupling diffractive element. The relay diffractive element is located above the out-coupling diffractive element. A remaining space of the out-coupling diffractive element is small, and a range of an exit pupil is small. A space occupied by the relay diffractive element is large. A volume and a weight of the waveguide display device are relatively large, which is not conducive to the miniaturization design of the waveguide display device.

The basic principle of the near-to-eye display technology is described below.

There are two kinds of the near-to-eye display technology based on diffractive optics, namely a waveguide device based on a surface relief grating and a waveguide device based on a volume holographic grating. The embodiments of the present invention mainly describe the waveguide device of the volume holographic grating.

The mathematical expression of the coupled wave theory includes coupling differential equations derived from the wave equation, whose main principle is that individual light waves continuously exchange energy in the process of propagation inside the hologram. Kogelnik coupled wave theory is widely used to analyze diffraction characteristics of various volume gratings and give a quantitative result. Since the Kogelnik theory implies the assumption that a wavefront size of a light participating in diffraction is infinite, only a change of the light during propagation along a thickness direction of the grating is studied under this assumption. Thus, the Kogelnik theory is essentially a one-dimensional theory. A two-dimensional theory assumes that properties of a material and properties of the light wave are all unchanged in a direction along a grating fringe plane. Usually, this direction is designated as a direction of an electric vector of the light wave. A size of the grating is limited in two directions perpendicular to the grating fringe plane, so that the light waves couple with each other and change uniformly in the two directions.

<FIG> is a schematic view of various geometric parameters in a formation stage of a two-dimensional confined volume grating. <FIG> is a schematic view of various geometric parameters in a readout stage of a two-dimensional confined volume grating. A reference light with a width of WR and a signal light with a width of WS are incident into a medium and interfere with each other inside the medium to form a volume grating. A coordinate system is selected so that the reference light and the signal light are incident at an angle φ0 and an angle -φ0 relative to an X axis, respectively. The formed grating is denoted as a periodic change of a dielectric constant εr of the medium:
<MAT>.

In the equation, εr<NUM> is an average dielectric constant, and εr<NUM> is an amplitude of a change of the dielectric constant. εr<NUM> and εr<NUM> can be a complex value, an imaginary part of which represents a change of an average absorptivity and a modulation amplitude of the absorption grating, respectively. pi<NUM> is a wavefront phase function of a plane light wave, and is denoted in the X-Y coordinate system as pi<NUM> = x cos φ<NUM> - (-<NUM>)i y sin φ<NUM>, in which i (i = <NUM>, <NUM>) represents the reference light and the signal light, respectively. a<NUM> and a<NUM> represents normalized complex amplitude distributions on wave fronts of two writing light waves respectively, and β<NUM> is a propagation constant of the writing light wave.

For the two-dimensional grating, the category of the Bragg diffraction is considered, and a grating vector k is denoted as:
<MAT>.

A Bragg mismatch parameter δ in the grating vector k is denoted as:
<MAT>.

In the equation, β= 2π/λ is a propagation constant of a readout light wave, λ is a wavelength of the readout light wave, and Δφ and Δβ represent deviations of an angle and a wavelength of the readout light wave from the Bragg condition, respectively.

When discussing the diffraction characteristics of fully overlapped uniform grating (A* is constant), for a two-dimensional finite-size volume grating, a grating diffraction efficiency is defined as:
<MAT>.

In view of the above existing technical problems, in some embodiments of the present invention, a waveguide display device includes: a waveguide substrate and a first optical element, a second optical element and a third optical element arranged coupled to the waveguide substrate. The first optical element is configured to couple an incident light into the waveguide substrate. The waveguide substrate is configured to couple the light coupled-in by the first optical element to the second optical element. The second optical element is configured to couple the light coupled to it by the waveguide substrate to the third optical element in a first direction and a second direction. The third optical element is configured to couple the light coupled to it by the second optical element to the second optical element in the first direction or the second direction, and to couple the light coupled to it by the second optical element out to a human eye. The second optical element and the third optical element are arranged at a first surface and a second surface of the waveguide substrate, respectively, and a relay optical element is omitted, so that the second optical element and the third optical element provide a large design space, thus reducing a volume and a weight of the waveguide display device. Moreover, the light coupled to the second optical element continues to propagate many times between the second optical element and the third optical element in the first direction or the second direction, so as to realize a two-dimensional mydriasis.

In this embodiment, an augmented reality display apparatus includes but is not limited to AR glasses, an AR head-mounted display apparatus and a head-up display apparatus. When the augmented reality display apparatus includes the AR glasses, the type of the AR glasses is not limited, which can be monocular AR glasses or binocular AR glasses.

In an embodiment, when the augmented reality display apparatus includes the AR glasses, the AR glasses include a frame, a waveguide display device and an optical machine. The waveguide display device and the optical machine are arranged on the frame. The waveguide display device serves as a lens of the AR glasses, and the optical machine sends an image light to the waveguide display device. The optical machine is not limited in the present invention, as long as it can emit a light to the waveguide display device. That is, any light emitter known in the related art may be used herein. The waveguide display device will be described in detail in subsequent embodiments, and will not be repeated in this embodiment.

In another embodiment, when the augmented reality display apparatus is the head-up display apparatus, the head-up display apparatus includes a body, a waveguide display device and an optical machine. The body and the optical machine are arranged on the body. The optical machine is not limited in the present invention, as long as it can emit a light to the waveguide display device. That is, any light emitter known in the related art may be used herein. The waveguide display device will be described in detail in subsequent embodiments, and will not be repeated in this embodiment.

In the above embodiments, the optical machine provides a collimated image source by projection.

<FIG> is a schematic view of a waveguide display device <NUM> according to an embodiment of the present invention. <FIG> is an exploded view of a waveguide display device according to an embodiment of the present invention. As shown in <FIG> and <FIG>, a waveguide display device <NUM> includes a waveguide substrate <NUM> and a first optical element <NUM>, a second optical element <NUM> and a third optical element <NUM> arranged coupled to the waveguide substrate <NUM>. As used herein the first and second sides of waveguide substrate <NUM> are relative to the X axis of <FIG>. The first and second surfaces of waveguide substrate <NUM> are relative to the Z axis of <FIG>. The first optical element <NUM> is located on a first side of the waveguide substrate <NUM>. For example, the first optical element <NUM> is located at a right part of the waveguide substrate <NUM> in <FIG> and <FIG>. The first optical element <NUM> is arranged adjacent to a first surface of the waveguide substrate <NUM> and configured to couple an incident light into the waveguide substrate <NUM>. The first surface of the waveguide substrate <NUM> is a side surface of the waveguide substrate <NUM> facing away from the human eye. The waveguide substrate <NUM> is configured to couple the light coupled-in by the first optical element <NUM> to the second optical element <NUM>. The second optical element <NUM> and the third optical element <NUM> are located on a second side of the waveguide substrate <NUM>. For example, the second optical element <NUM> and the third optical element <NUM> are located at a left part of the waveguide substrate <NUM> in <FIG> and <FIG>. The second optical element <NUM> is arranged adjacent to a second surface of the waveguide substrate <NUM> and is configured to couple the light coupled to it by the waveguide substrate <NUM> to the third optical element <NUM> in a first direction and a second direction when viewed in a direction perpendicular to a plane where the third optical element <NUM> is located. The second surface of the waveguide substrate <NUM> is a side surface of the waveguide substrate <NUM> facing the human eye. The first direction and the second direction are directions defined in the plane where the third optical element <NUM> is located. That is, the first direction and the second direction have no component in the direction perpendicular to the plane where the third optical element <NUM> is located. The third optical element <NUM> is arranged adjacent to the first surface of the waveguide substrate <NUM> and configured to couple the light coupled to it by the second optical element <NUM> to the second optical element <NUM> in the first direction or the second direction when viewed in a direction perpendicular to the plane where the third optical element <NUM> is located, and to couple the light coupled to it by the second optical element <NUM> out to the human eye. Moreover, the light coupled to the second optical element <NUM> continues to propagate many times between the second optical element <NUM> and the third optical element <NUM> in the first direction or the second direction.

In some embodiments, the first optical element <NUM> and the third optical element <NUM> are on the first surface of the waveguide substrate <NUM> and spaced apart from each other, and the second optical element <NUM> is on the second surface of the waveguide substrate <NUM> and opposite to the third optical element <NUM>.

The waveguide display device according to the embodiments of the present invention includes the waveguide substrate and the first optical element, the second optical element and the third optical element coupled to the waveguide substrate. The first optical element is configured to couple the incident light into the waveguide substrate. The waveguide substrate is configured to couple the light coupled-in by the first optical element to the second optical element. The second optical element is configured to couple the light coupled to it by the waveguide substrate to the third optical element in the first direction and the second direction. The third optical element is configured to couple the light coupled to it by the second optical element to the second optical element in the first direction or the second direction, and to couple the light coupled to it by the second optical element out to the human eye. The second optical element and the third optical element are arranged at the first surface and the second surface of the waveguide substrate, respectively, and a relay optical element is omitted, so that a volume and a weight of the waveguide display device are reduced. Moreover, the light coupled to the second optical element continues to propagate many times between the second optical element and the third optical element in the first direction or the second direction, so as to realize a two-dimensional mydriasis.

<FIG> is a scene view of a waveguide display device <NUM> according to an embodiment of the present invention. As shown in <FIG>, the light is incident on a surface of the first optical element <NUM>, and the first optical element <NUM> forwards the incident light to go through action of the waveguide substrate <NUM>, the second optical element <NUM> and the third optical element <NUM>, so as to realize the two-dimensional mydriasis in a X-axis direction and a Y-axis direction shown in <FIG>. Then, the light is incident on the human eye, and a virtual field of view is formed in front of the human eye.

It should be noted that, in <FIG>, a X axis of a coordinate system is parallel to a length direction of the waveguide display device <NUM> or a horizontal axis of the virtual field of view, a Y axis of the coordinate system is parallel to a width direction of the waveguide display device <NUM>, and a Z axis of the coordinate system is perpendicular to the waveguide display device or parallel to a thickness direction of the waveguide display device <NUM>.

<FIG> is a schematic view of light propagation of a waveguide display device <NUM> according to an embodiment of the present invention. <FIG> is a schematic view of light propagation in a X-axis direction and a Z-axis direction according to an embodiment of the present invention. <FIG> is a schematic view of light propagation in a Y-axis direction and a Z-axis direction according to an embodiment of the present invention.

It should be noted that, for an illustrative purpose, embodiments of <FIG> and <FIG> take any one (a light L1) of lights emitted by the optical machine as an example. A light <MAT> in <FIG> is the light incident on the second optical element <NUM> from the waveguide substrate <NUM>. The following embodiments are described with reference to any light L1.

In the above embodiments, as shown in <FIG>, the light L1 emitted by the optical machine is incident on the first optical element <NUM> and is diffracted into the waveguide substrate <NUM> by the first optical element <NUM>. The waveguide substrate <NUM> is configured to couple the light coupled-in by the first optical element <NUM> to the second optical element <NUM>. A method in which the waveguide substrate <NUM> couples the light coupled-in by the first optical element <NUM> to the second optical element <NUM>, includes but is not limited to following light processing methods.

First Light processing method: the waveguide substrate <NUM> is configured to directly couple the light coupled-in by the first optical element <NUM> to the second optical element <NUM>. In this light processing method, a relative position of the first optical element <NUM> and the second optical element <NUM> may be adjusted, so as to directly couple the light coupled-in by the first optical element <NUM> to the second optical element <NUM> through the waveguide substrate <NUM>.

Second light processing method: the waveguide substrate <NUM> is configured to couple the light coupled-in by the first optical element <NUM> to the second optical element <NUM> after the light coupled-in by the first optical element <NUM> goes through at least one total reflection inside the waveguide substrate <NUM>. As shown in <FIG>, the light coupled-in by the first optical element <NUM> meets a condition of the total reflection in the waveguide substrate <NUM>, and the light coupled-in by the first optical element <NUM> forms the light <MAT> after the total reflection and the light <MAT> is incident on the second optical element <NUM>.

In some embodiments, the first direction is perpendicular to the second direction. In some embodiments, the first direction is parallel to the X axis of the coordinate system, and the second direction is parallel to the Y axis of the coordinate system. It should be noted that the first direction and the second direction may not be parallel to the X axis of the coordinate system or the Y axis of the coordinate system. In this case, an inclined virtual field of view is formed in front of the human eye.

In some embodiments, the first optical element <NUM>, the second optical element <NUM> and the third optical element <NUM> are nanostructures to diffract the incident light.

In the above embodiments, the second optical element <NUM> is configured to couple the light coupled to it by the waveguide substrate <NUM> to the third optical element <NUM> by total reflection in the first direction, and to couple the light coupled to it by the waveguide substrate <NUM> to the third optical element <NUM> by diffraction in the second direction. As shown in <FIG>, <FIG>, the light coupled-in by the first optical element <NUM> forms the light <MAT> after the total reflection and the light <MAT> is incident on the second optical element <NUM> at a point A1. The light <MAT> meets the condition of the total reflection at the point A1. The second optical element <NUM> reflects the light <MAT> at the point A1 to a point B of the third optical element <NUM> along the X-axis direction of the coordinate system by total reflection, and the light reflected by the second optical element <NUM> at the point A1 is a zero order light. The second optical element <NUM> couples the light <MAT> at the point A1 out to a point C of the third optical element <NUM> along the Y-axis direction of the coordinate system by diffraction, and the light generated by the second optical element <NUM> at the point A1 by the diffraction is a diffraction order light.

In the above embodiments, the third optical element <NUM> is configured to couple the light coupled to it by the second optical element <NUM> to the second optical element <NUM> in the first direction or the second direction by total reflection, and to couple the light coupled to it by the second optical element <NUM> out to the human eye by diffraction. The third optical element <NUM> is configured to couple the light coupled to it by the second optical element <NUM> out to the human eye in the direction perpendicular to the plane where the third optical element <NUM> is located. As shown in <FIG>, <FIG>, the light coupled by the second optical element <NUM> meets the condition of the total reflection at the point B, the third optical element <NUM> is configured to reflect the light coupled to it by the second optical element <NUM> at the point B to a point A2 of the second optical element <NUM> along the X-axis direction of the coordinate system by total reflection, and also, the third optical element <NUM> is configured to couple the light coupled to it by the second optical element <NUM> at the point B out to the human eye by diffraction. The light coupled by the second optical element <NUM> meets the condition of the total reflection at the point C, the third optical element <NUM> is configured to reflect the light coupled to it by the second optical element <NUM> at the point C to a point A5 of the second optical element <NUM> along the Y-axis direction of the coordinate system by total reflection, and also, the third optical element <NUM> is configured to couple the light coupled to it by the second optical element <NUM> at the point C out to the human eye by diffraction.

It may be understood that, for convenient and easy understanding of the present invention, a travel path of the light is mainly described in the plane where the third optical element <NUM> is located, i.e. a projection of the travel path of the light on the plane where the third optical element <NUM> is located is mainly described.

However, in the above embodiments, the light coupled to the second optical element <NUM> from the third optical element <NUM> continues to propagate many times between the second optical element <NUM> and the third optical element <NUM> in the first direction or the second direction, that is, the light actually has a displacement in the direction (i.e. the Z-axis direction) perpendicular to the plane where the third optical element <NUM> is located. As shown in <FIG>, the light coupled to the second optical element <NUM> from the third optical element <NUM> continues to propagate many times between the second optical element <NUM> and the three optical elements <NUM> along the X-axis direction and the Z-axis direction of the coordinate system, and as shown in <FIG>, the light coupled to the second optical element <NUM> from the third optical element <NUM> continues to propagate many times between the second optical element <NUM> and the three optical elements <NUM> along the Y-axis direction and the Z-axis direction of the coordinate system, so as to realize the two-dimensional mydriasis.

It should be noted that, as shown in <FIG>, the zero order light and the diffraction order light are subject to exactly identical modulation at the point A1, the point A2, a point A3, a point A4 and the point A5 in the drawings. A light intensity may be adjusted according to requirements of a brightness uniformity of an actual field of view. In the actual processing, a photomask may be arranged to control a grating efficiency.

In some embodiments, the second optical element <NUM> and the third optical element <NUM> are opposite to each other, and an area of the second optical element <NUM> and an area of the third optical element <NUM> are equal. The second optical element <NUM> and the third optical element <NUM> are opposite to each other, so that a relay optical element does not need to be arranged, so as to reserve a design space for the second optical element <NUM> and the third optical element <NUM>. In this way, the second optical element <NUM> and the third optical element <NUM> may adopt a larger area, thus improving a range of the mydriasis, reasonably setting a position of an exit pupil area and ensuring a reasonable observation range. The area of the second optical element <NUM> and the area of the third optical element <NUM> are equal, so that the second optical element <NUM> and the third optical element <NUM> may be processed simultaneously, thus improving the production efficiency of the elements.

In some embodiments, the first optical element <NUM>, the second optical element <NUM> and the third optical element <NUM> are arranged adjacent to the surfaces of the waveguide substrate <NUM>. As shown in <FIG>, the first optical element <NUM> covers at least a part of the first surface of the waveguide substrate <NUM>, the second optical element <NUM> covers at least a part of the second surface of the waveguide substrate <NUM>, and the third optical element <NUM> covers at least another part of the first surface of the waveguide substrate <NUM>. In the embodiments of the present invention, the first optical element <NUM>, the second optical element <NUM> and the third optical element <NUM> may be adjusted according to the actual situation. For example, the first optical element <NUM>, the second optical element <NUM> and the third optical element <NUM> may be embedded inside the waveguide substrate <NUM> in a totally enclosed form. In some embodiments, the surface of the waveguide substrate <NUM> is provided with a groove, and the first optical element <NUM>, the second optical element <NUM> and the third optical element <NUM> are mounted in the groove in the surface of the waveguide substrate <NUM> in a semi-enclosed form.

In some embodiments, the second optical element <NUM> and the third optical element <NUM> are parallel to each other. The second optical element <NUM> and the third optical element <NUM> may adopt same grating structure parameters, so as to symmetrically modulate the light.

In some embodiments, the first optical element <NUM> is a one-dimensional grating. The one-dimensional grating includes but is not limited to any one of the following gratings: an inclined grating, a rectangular grating, a blazed grating and a volume grating. The second optical element <NUM> and the third optical element <NUM> are the two-dimensional gratings. The first optical element <NUM> is a holographic one-dimensional grating, and the second optical element <NUM> and the third optical element <NUM> are holographic two-dimensional gratings. The second optical element <NUM> and the third optical element <NUM> in the present invention adopt the holographic two-dimensional grating, so that the efficiency of the diffraction waveguide can be greatly improved.

The technical solution of the embodiments of the present invention is described in detail below in combination with <FIG>.

As shown in <FIG>, the light coupled-in by the first optical element <NUM> meets the condition of the total reflection in the waveguide substrate <NUM>, the light coupled-in by the first optical element <NUM> forms the light <MAT> after the total reflection and the light <MAT> is incident on the second optical element <NUM>.

As shown in <FIG> and <FIG>, the light coupled-in by the first optical element <NUM> forms the light <MAT> after the total reflection and the light is incident on the point A1 of the second optical element <NUM>. The light <MAT> meets the condition of total reflection at the point A1. The second optical element <NUM> reflects the light <MAT> at the point A1 to the point B of the third optical element <NUM> along the X-axis direction of the coordinate system by total reflection, and the light reflected by the second optical element <NUM> at the point A1 is the zero order light. The second optical element <NUM> couples the light <MAT> at the point A1 to the point C of the third optical element <NUM> along the Y-axis direction of the coordinate system by diffraction, and the light generated by the second optical element <NUM> at the point A1 by diffraction is the diffraction order light.

As shown in <FIG> and <FIG>, the light coupled by the second optical element <NUM> meets the condition of total reflection at the point B, the third optical element <NUM> is configured to reflect the light coupled to it by the second optical element <NUM> at the point B to the point A2 of the second optical element <NUM> along the X-axis direction of the coordinate system by total reflection, and also, the third optical element <NUM> is configured to couple the light coupled to it by the second optical element <NUM> at the point B out to the human eye. The light coupled by the second optical element <NUM> meets the condition of total reflection at the point C, the third optical element <NUM> is configured to reflect the light coupled to it by the second optical element <NUM> at the point C to the point A5 of the second optical element <NUM> along the Y-axis direction of the coordinate system by total reflection, and also, the third optical element <NUM> is configured to couple the light coupled to it by the second optical element <NUM> at the point C out to the human eye by diffraction.

As shown in <FIG>, the light coupled to the second optical element <NUM> from the third optical element <NUM> continues to propagate many times between the second optical element <NUM> and the three optical element <NUM> along the X-axis direction and Z-axis direction of the coordinate system, and as shown in <FIG>, the light coupled to the second optical element <NUM> from the third optical element <NUM> continues to propagate many times between the second optical element <NUM> and the three optical elements <NUM> along the Y-axis direction and the Z-axis direction of the coordinate system, so as to realize the two-dimensional mydriasis.

<FIG> is a schematic view of AR glasses according to an embodiment of the present invention. Taking a scene of the AR glasses as an example, the technical solution of the present invention is described in combination with <FIG>.

As shown in <FIG>, the AR glasses <NUM> include a frame <NUM>, the waveguide display device <NUM> according to any one of the above embodiments and an optical machine <NUM>, and the waveguide display device <NUM> and the optical machine <NUM> are arranged on the frame <NUM>. The frame <NUM> includes an eyeglass frame <NUM> and lens legs <NUM> connected to two sides of the eyeglass frame <NUM>. The optical machine <NUM> may be arranged on the eyeglass frame <NUM> or on the lens leg <NUM> on either side.

In the waveguide display device <NUM> according to the embodiments of the present invention, the second optical element <NUM> and the third optical element <NUM> are arranged at the first surface and the second surface of the waveguide substrate <NUM>, respectively. The relay optical element is omitted, so that a large design space is provided for the second optical element <NUM> and the third optical element <NUM>, a range of the mydriasis of the waveguide display device <NUM> is increased, and an observable range for the human eye to watch a virtual image in a real scene through the AR glasses is increased. The virtual image in the real scene can be watched through the AR glasses no matter the AR glasses are offset upwards, downwards, leftwards or rightwards relative to human eye, thus improving the user experience. The AR glasses may be adapted to users having different habits of wearing AR glasses.

<FIG> is a scene view of a head-up display apparatus according to an embodiment of the present invention. Taking the scene of the head-up display apparatus as an example, the technical solution of the present invention is described in combination with <FIG>.

The augmented reality display apparatus is arranged on a front windshield of a vehicle. The augmented reality display apparatus includes the waveguide display device <NUM> according to any one of the above embodiments and an optical machine. Part of the front glass of the vehicle may be configured as the waveguide substrate <NUM> of the augmented reality display apparatus. The first optical element <NUM>, the second optical element <NUM> and the third optical element <NUM> may be arranged on a surface of the part of the glass.

In the waveguide display device <NUM> according to the embodiments of the present invention, the second optical element <NUM> and the third optical element <NUM> are arranged at the first surface and the second surface of the waveguide substrate <NUM>, respectively. The relay optical element is omitted, so that a large design space is provided for the second optical element <NUM> and the third optical element <NUM>, a range of the mydriasis of the waveguide display device <NUM> is increased, and an observable range for the human eye to watch a virtual image in a real scene through the head-up display apparatus is increased. Moreover, the observable range for the human eye to watch the virtual image in the real scene through the head-up display apparatus may be adjusted by reasonably setting positions and sizes of the second optical element <NUM> and the third optical element <NUM>.

Claim 1:
A waveguide display device (<NUM>), comprising a waveguide substrate (<NUM>) and a first optical element (<NUM>), a second optical element (<NUM>) and a third optical element (<NUM>) coupled to the waveguide substrate (<NUM>), wherein
the first optical element (<NUM>) is located on a first side of the waveguide substrate (<NUM>), the first optical element (<NUM>) is adjacent to a first surface of the waveguide substrate (<NUM>) and configured to couple an incident light into the waveguide substrate (<NUM>), and the first surface of the waveguide substrate (<NUM>) is a surface of the waveguide substrate (<NUM>) facing away from a human eye;
the waveguide substrate (<NUM>) is configured to couple the light coupled-in by the first optical element (<NUM>) to the second optical element (<NUM>);
the second optical element (<NUM>) and the third optical element (<NUM>) are located on a second side of the waveguide substrate (<NUM>); and
the third optical element (<NUM>) is configured to couple the light coupled to it by the second optical element (<NUM>) to the second optical element (<NUM>) in the first direction or the second direction when viewed in the direction perpendicular to the plane where the third optical element (<NUM>) is located, and to couple the light coupled to it by the second optical element (<NUM>) out to the human eye, and the light coupled to the second optical element (<NUM>) continues to propagate many times between the second optical element (<NUM>) and the third optical element (<NUM>) in the first direction or the second direction,
characterized in that,
the second optical element (<NUM>) is adjacent to a second surface of the waveguide substrate (<NUM>), the second optical element (<NUM>) is configured to couple the light coupled to it by the waveguide substrate (<NUM>) to the third optical element (<NUM>) in a first direction and a second direction when viewed in a direction perpendicular to a plane where the third optical element (<NUM>) is located, and the second surface of the waveguide substrate (<NUM>) is a surface of the waveguide substrate (<NUM>) facing the human eye,
the third optical element (<NUM>) is arranged adjacent to the first surface of the waveguide substrate (<NUM>).