Multi-focal-plane holographic optical waveguide display system

Abstract

The present application provides a multi-focal-plane holographic optical waveguide display system, comprising polarized image light sources, a first optical waveguide, and a second optical waveguide. At different moments, a holographic optical element responds to different polarization states, such that an optical waveguide AR display picture is imaged at different distances directly in front of human eyes, thereby forming a plurality of focal planes for display, effectively mitigating the problem of vergence-accommodation conflict of human eyes, and having the advantages such as high transmittance and diffraction efficiency, low process manufacturing cost, and an ultra-slim, lightweight form factor.

Description

A multi-focal holographic optical waveguide display system TECHNICAL FIELD

[0001] Embodiments of the present application belong to the technical field of optical waveguide display, and particularly relate to a multi-focal holographic optical waveguide display system. BACKGROUND

[0002] Optical waveguide display technology is an important development direction in the field of augmented reality (AR), which enables users to see virtual images provided by the device while seeing the real world, that is, to superimpose virtual information in the real world, thereby providing the user with an "enhanced" display effect, and the AR optical waveguide technology has the advantages of light and thin, and has become a hot spot in the field of wearable consumer electronics.

[0003] At present, in order to obtain 3D display effect, the near-eye display optical system usually displays independent pictures with a certain field of view for the left and right eyes to simulate a real scene, and the brain perceives the 3D display effect after fusion. However, this conventional technical solution will cause the distance of the eye lens adjustment to be always focused on the virtual image plane of the micro-display image source of the near-eye display optical system, that is, the eye adjustment distance is a fixed value, and on the other hand, due to the setting of the left and right eye pictures with parallax, the brain will feel the nearness and remoteness of the 3D picture object, causing the human eye vergence distance to change with the content of the built-in sheet source picture. Thus, the human eye focus adjustment and the screen information depth do not match, that is, vergence-accommodation conflict (hereinafter referred to as VAC) occurs, which causes human eye visual fatigue, dizziness, vomiting and other phenomena. TECHNICAL PROBLEM

[0004] In order to solve the problem of visual vergence-accommodation conflict, some existing technologies use multi-layer optical waveguide technology, but the disadvantage is that the volume is relatively large and the transmittance is low; some use micro-lens array (Micro-lens array) light field display technology, but the disadvantage is that it will seriously reduce the display resolution of the image. Some use electronic or mechanical zoom lens technology, but the disadvantage is that it is affected by factors such as zoom lens imaging quality and relative response speed. Therefore, there is an urgent need to develop a multi-focal display optical system to effectively solve the problem of visual vergence-accommodation conflict, thereby reducing the visual discomfort of the wearer. TECHNICAL SOLUTION

[0005] In order to solve or alleviate the problems in the prior art, the present application provides a multi-focal holographic optical waveguide display system, which can make the optical waveguide AR display image be formed at different distances in front of the human eye, forming multiple focal plane displays, effectively alleviating the visual vergence-accommodation conflict problem of the human eye, and having the advantages of high transmittance, high diffraction efficiency, low process preparation cost, light and thin volume, etc.

[0006] The embodiment of the present application provides a multi-focal-plane holographic optical waveguide display system, comprising a polarized image light source, a first optical waveguide and a second optical waveguide;

[0007] First and second gratings are arranged between the first and second optical waveguides;

[0008] First and second polarization state image light processing devices are arranged on the side of the second optical waveguide away from the first optical waveguide, and the first and second polarization state image light processing devices are arranged in regions corresponding to the positions of the first and second gratings;

[0009] The first polarization state image light processing device comprises first and second phase delay devices, third and fourth gratings;

[0010] The second polarization state image light processing device comprises third and fourth phase delay devices, first and second lenses;

[0011] After the polarized image light source emits first and second polarized light, the first polarized light is diffracted in the first grating after passing through the first optical waveguide, continues to be reflected in the first optical waveguide, and is output to the human eye to form an image after passing through the second grating and the first optical waveguide, thereby obtaining a first focal plane;

[0012] The second polarized light is diffracted in the first grating, passes through the second optical waveguide, the first phase delay device, the second phase delay device, the third or fourth grating, the second phase delay device, the first phase delay device, continues to be reflected in the second optical waveguide, then passes through the third phase delay device, the fourth phase delay device, the first or second lens, the fourth phase delay device, the third phase delay device, is transmitted to the second grating through the second optical waveguide, and is finally transmitted to the human eye through the first optical waveguide, the second polarized light is synchronously subjected to phase delay of different preset angles by adjusting the first and third phase delay devices, and then the second polarized light at different moments is output to the human eye through the second optical waveguide to form an image, thereby obtaining a second and third focal plane.

[0013] As a preferred embodiment of the present application, the first and third phase delay devices are electrically controlled 1 / 2 wave plates, and the second and fourth phase delay devices are electrically controlled 1 / 4 wave plates.

[0014] As a preferred embodiment of the present application, the third grating is a left-handed circularly polarized light response polarization volume holographic grating, the fourth grating is a right-handed circularly polarized light response polarization volume holographic grating, the first lens is a left-handed circularly polarized light response polarization volume holographic lens, and the second lens is a right-handed circularly polarized light response polarization volume holographic lens.

[0015] The first polarized light is P light, which is diffracted in the first grating in sequence after passing through the first optical waveguide, continues to be reflected in the first optical waveguide, and is output to the human eye to form an image in sequence after passing through the second grating and the first optical waveguide, thereby obtaining a first focal plane.

[0016] The second polarized light is S light, the first phase delay device and the third phase delay device are adjusted to perform phase delay at a first preset angle, so that the phase delay amount of the second polarized light is 0 phase, the second polarized light is diffracted by the first grating, and then sequentially passes through the second optical waveguide, the first phase delay device, the second phase delay device, the third grating, the second phase delay device, and the first phase delay device, continues to be reflected in the second optical waveguide, and then sequentially passes through the third phase delay device, the fourth phase delay device, the first lens, the fourth phase delay device, and the third phase delay device, is transmitted to the second grating through the second optical waveguide, and is finally transmitted to the human eye through the first optical waveguide, the first phase delay device and the third phase delay device are adjusted to perform phase delay at different preset angles on the second polarized light at the same time, thereby making the second polarized light output to the human eye through the second optical waveguide to form an image, and a second focal plane is obtained.

[0017] The second polarized light is S light, the first phase delay device and the third phase delay device are adjusted to perform phase delay at a first preset angle, so that the phase delay amount of the second polarized light is Pi phase, the second polarized light is diffracted by the first grating, and then sequentially passes through the second optical waveguide, the first phase delay device, the second phase delay device, the fourth grating, the second phase delay device, and the first phase delay device, continues to be reflected in the second optical waveguide, and then sequentially passes through the third phase delay device, the fourth phase delay device, the second lens, the fourth phase delay device, and the third phase delay device, is transmitted to the second grating through the second optical waveguide, and is finally transmitted to the human eye through the first optical waveguide, the first phase delay device and the third phase delay device are adjusted to perform phase delay at different preset angles on the second polarized light at the same time, thereby making the second polarized light output to the human eye through the second optical waveguide to form an image, and a third focal plane is obtained.

[0018] As a preferred embodiment of the present application, the polarized image light source comprises a first polarized image light source and a second polarized image light source, the first polarized image light source is used to emit first polarized light, and the second polarized image light source is used to emit second polarized light.

[0019] As a preferred embodiment of the present application, the first grating, the second grating, the third grating, the fourth grating, the first lens and the second lens are all reflective optical elements.

[0020] As a preferred embodiment of the present application, the polarized image light source is provided with an optical beam splitting device between the first optical waveguide. Advantages

[0021] Compared with the prior art, the embodiment of the present application provides a multi-focal-plane holographic optical waveguide display system. At different moments, the response of the holographic optical element to different polarization states makes the AR display image of the optical waveguide be imaged at different distances in front of the human eye, forming multi-focal-plane display, effectively relieving the visual vergence accommodation conflict problem of the human eye, and having the advantages of high transmittance, high diffraction efficiency, low process preparation cost, light and thin volume, etc. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, will be described in detail with reference to these accompanying drawings, in which specific embodiments of the application are illustrated and described, which are exemplary and not limiting of the application. Some embodiments of the application will be described in detail with reference to the drawings, wherein like reference numerals refer to like parts throughout the several views. The drawings are in simplified form and are not to precise scale. In the drawings:

[0023] Fig. 1 is a structure schematic diagram of an optical path of a multi-focal-plane holographic optical waveguide display system according to an embodiment of the present application;

[0024] Fig. 2 is a polarization conversion principle schematic diagram of a first polarization state image light processing device at t2;

[0025] Fig. 3 is a polarization conversion principle schematic diagram of a second polarization state image light processing device at t2;

[0026] Fig. 4 is a polarization conversion principle schematic diagram of a first polarization state image light processing device at t3;

[0027] Fig. 5 is a polarization conversion principle schematic diagram of a second polarization state image light processing device at t3. Best Mode for Carrying Out the Invention

[0028] In the following, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application, so that those skilled in the art can better understand the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should be within the scope of protection of the present application.

[0029] As shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5, the present application provides a multi-focal holographic optical waveguide display system, which comprises a polarized image light source, a first optical waveguide 4 and a second optical waveguide 5;

[0030] The first optical waveguide 4 and the second optical waveguide 5 are spaced apart by a first grating 6 and a second grating 8;

[0031] The second optical waveguide 5 is spaced apart by a first polarization state image light processing device 7 and a second polarization state image light processing device 9 on the side away from the first optical waveguide 4, and the first polarization state image light processing device 7 and the second polarization state image light processing device 9 are arranged in the regions corresponding to the positions of the first grating 6 and the second grating 8, respectively;

[0032] The first polarization state image light processing device 7 comprises a first phase delay device 71, a second phase delay device 72, a third grating 73 and a fourth grating 74;

[0033] The second polarization state image light processing device 9 comprises a third phase delay device 91, a fourth phase delay device 92, a first lens 93 and a second lens 94;

[0034] After the polarized image light source emits first polarized light or second polarized light, the first polarized light is diffracted in the first grating 6 after passing through the first optical waveguide 4 in sequence, continues to be reflected in the first optical waveguide 4, and is output to the human eye 10 to form an image after passing through the second grating 8 and the first optical waveguide 4 in sequence, thereby obtaining a first focal plane;

[0035] The second polarized light is diffracted by the first grating 6, and then is reflected in the second optical waveguide 5, the first phase delay device 71, the second phase delay device 72, the third grating 73 or the fourth grating 74, the second phase delay device 72, the first phase delay device 71, and then is transmitted to the second grating 8 through the second optical waveguide 5, and finally is transmitted to the human eye 10 through the first optical waveguide 4. By adjusting the phase delay of the first phase delay device 71 and the third phase delay device 91 on the second polarized light at different preset angles, the second polarized light at different times is imaged as the second focal plane and the third focal plane when output to the human eye 10 through the second optical waveguide 5.

[0036] Specifically, the first phase delay device 71 and the third phase delay device 91 are both electrically controlled 1 / 2 wave plates, and the second phase delay device 72 and the fourth phase delay device 92 are both electrically controlled 1 / 4 wave plates.

[0037] Specifically, the third grating 73 is a left-handed circularly polarized light response polarization volume holographic grating, the fourth grating 74 is a right-handed circularly polarized light response polarization volume holographic grating, the first lens 93 is a left-handed circularly polarized light response polarization volume holographic lens, and the second lens 94 is a right-handed circularly polarized light response polarization volume holographic lens.

[0038] The first polarized light is P light, which is diffracted in the first grating 6 after passing through the first optical waveguide 4, and then is reflected in the first optical waveguide 4, and is output to the human eye 10 to form the first focal plane after passing through the second grating 8 and the first optical waveguide 4.

[0039] The second polarized light is S light, the first phase delay device 71 and the third phase delay device 91 are adjusted to have a first preset angle of phase delay, so that the phase delay of the second polarized light is 0 phase, after the first grating 6 diffracts the second polarized light, the second polarized light is sequentially reflected in the second optical waveguide 5, the first phase delay device 71, the second phase delay device 72, the third grating 73, the second phase delay device 72 and the first phase delay device 71, then sequentially passes through the third phase delay device 91, the fourth phase delay device 92, the first lens 93, the fourth phase delay device 92 and the third phase delay device 91, and is transmitted to the second grating 8 through the second optical waveguide 5, and finally is transmitted to the human eye 10 through the first optical waveguide 4, by adjusting the first phase delay device 71 and the third phase delay device 91 to have different preset angles of phase delay on the second polarized light, the second polarized light is imaged to the human eye 10 through the second optical waveguide 5, and a second focal plane is obtained.

[0040] The second polarized light is S light, the first phase delay device 71 and the third phase delay device 91 are adjusted to have a first preset angle of phase delay, so that the phase delay of the second polarized light is Pi phase, after the first grating 6 diffracts the second polarized light, the second polarized light is sequentially reflected in the second optical waveguide 5, the first phase delay device 71, the second phase delay device 72, the fourth grating 74, the second phase delay device 72 and the first phase delay device 71, then sequentially passes through the third phase delay device 91, the fourth phase delay device 92, the second lens 94, the fourth phase delay device 92 and the third phase delay device 91, and is transmitted to the second grating 8 through the second optical waveguide 5, and finally is transmitted to the human eye 10 through the first optical waveguide 4, by adjusting the first phase delay device 71 and the third phase delay device 91 to have different preset angles of phase delay on the second polarized light, the second polarized light is imaged to the human eye 10 through the second optical waveguide 5, and a second focal plane is obtained.

[0041] That is, when the second polarized light is S light, the second polarized light after diffracting through the first grating 6 enters the first polarization state image light processing device 7 for processing, and the first phase delay device 71 is set to have a phase delay greater than 0 angle, after adjusting the phase delay of different angles, the second polarized light is imaged in the human eye 10, and a third focal plane is obtained.

[0042] When the first polarized light is P light, the first polarized light only reflects in the first optical waveguide 4, and when the first polarized light is coupled out of the first optical waveguide 4, it is imaged at the human eye 10, and a first focal plane is obtained.

[0043] Further, the polarized image light source comprises a first polarized image light source 1 and a second polarized image light source 2, the first polarized image light source 1 is used for emitting first polarized light, and the second polarized image light source 2 is used for emitting second polarized light.

[0044] In the embodiment of the present application, the first grating 6, the second grating 8, the third grating 73, the fourth grating 74, the first lens 93 and the second lens 94 are all reflective optical elements. Among them, the first grating 6, the third grating 73 and the fourth grating 74 are in-coupling optical elements, and the second grating 8, the first lens 93 and the second lens 94 are out-coupling optical elements.

[0045] As a preferred embodiment of the present application, the first phase delay device 71 and the third phase delay device 91 are both electrically controlled 1 / 2 wave plates, and the second phase delay device 72 and the fourth phase delay device 92 are both electrically controlled 1 / 4 wave plates.

[0046] The following takes forming three focal planes as an example to explain the technical solution of the present application in detail:

[0047] The specific implementation of the optical path principle is shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5, which mainly includes a polarized image light source (composed of a micro display and a collimating lens assembly), a light beam splitter 3, a first optical waveguide 4, a first phase delay device 71, a second phase delay device 72, a third phase delay device 91 and a fourth phase delay device 92, and in-coupling and out-coupling optical elements; among them, the polarized image light source includes two, which respectively outputs P light and S light, and at different moments, the image information required for the corresponding focal plane is cyclically output; and the first phase delay device 71, the second phase delay device 72, the third phase delay device 91 and the fourth phase delay device 92 are used for phase delay modulation of the polarized light incident to the second optical waveguide 5; the in-coupling and out-coupling optical elements all include the third grating 73, the fourth grating 74, the first lens 93 and the second lens 94; among them, the third grating 73 is a left-handed circularly polarized light response polarization volume holographic grating, the fourth grating 74 is a right-handed circularly polarized light response polarization volume holographic grating, the first lens 93 is a left-handed circularly polarized light response polarization volume holographic lens, and the second lens 94 is a right-handed circularly polarized light response polarization volume holographic lens.

[0048] The in-coupling and out-coupling optical elements are all of the reflective type.

[0049] Firstly, a polarized image light source (P light is taken as an example, LCD, OLED, LCOS and other polarized display light sources) is selected, one of the polarized image light sources emits first polarized light as P light, and the other polarized image light source emits second polarized light as S light.

[0050] At t1, the first polarized light emitted by the first polarized image light source 1 is P light, and the second polarized image light source 2 does not emit polarized light. The first polarized light entering the first optical waveguide 4 is diffracted by the first grating 6 and propagates in the first optical waveguide 4 in the form of total reflection until it propagates to the second grating 8. The first polarized light is diffracted and coupled out of the first optical waveguide 4 by the second grating 8 and enters the human eye 10, and is imaged at infinity to obtain the first focal plane viewed by the human eye 10;

[0051] At t2, the second polarized light emitted by the second polarized image light source 2 is S light, and the first polarized image light source 1 does not emit polarized light. At this time, the second polarized light directly transmits through the first grating 6 and is incident on the first polarization state image light processing device 7 on the side surface of the second optical waveguide 5. At the same time, the first phase delay device 71 is set to 0 phase delay (45° angle with the optical axis), so that the second polarized light does not change polarization when passing through the first phase delay device 71 (electrically controlled 1 / 2 wave plate) and is incident on the second phase delay device 72 (electrically controlled 1 / 4 wave plate) to be modulated into left circularly polarized light. After being diffracted and reflected by the third grating 73, the second polarized light is converted into second polarized light again after passing through the second phase delay device 72 (electrically controlled 1 / 4 wave plate) and the first phase delay device 71 (electrically controlled 1 / 2 wave plate) and is transmitted in the second optical waveguide 5 to the third phase delay device 91 (electrically controlled 1 / 2 wave plate) and the fourth phase delay device 92 (electrically controlled 1 / 4 wave plate) in the form of total reflection. The first phase delay device 71 and the third phase delay device 91 have the same phase delay angle and are synchronized to perform phase delay. Subsequently, the second polarized light is converted into left circularly polarized light again and passes through the first lens 93, and is modulated by the fourth phase delay device 92 (electrically controlled 1 / 4 wave plate) and the third phase delay device 91 (electrically controlled 1 / 2 wave plate) again, so that the left circularly polarized light is converted into second polarized light again and can directly transmit through the second grating 8 to enter the human eye 10. Since the first lens 93 is a holographic optical element with lens divergence function, the coupled-out second polarized light will converge at a specific distance to obtain the second focal plane viewed by the human eye 10;

[0052] At time t3, the second polarized light emitted by the second polarized image light source 2 is S light, and the first polarized image light source 1 does not emit polarized light. At this time, the first polarized light directly transmits through the first grating 6 and is incident on the first polarization state image light processing device 7 of the second waveguide; at the same time, the first phase delay device 71 is set to have a phase delay amount of Pi phase (45° angle with the optical axis), so that the second polarized light is converted from S light to P light when passing through the first phase delay device 71 (electrically controlled 1 / 2 wave plate), and then is incident on the second phase delay device 72 (electrically controlled 1 / 4 wave plate) to be modulated into right circularly polarized light. After being diffracted by the fourth grating 74, the right circularly polarized light passes through the second phase delay device 72 (electrically controlled 1 / 4 wave plate) and the first phase delay device 71 (electrically controlled 1 / 2 wave plate) in turn, is reconverted into S light, and is transmitted in the form of total reflection in the second optical waveguide 5 to the third phase delay device 91 (electrically controlled 1 / 2 wave plate), wherein the first phase delay device 71 and the third phase delay device 91 have the same phase delay angle and perform phase delay synchronously. Subsequently, the S light is converted into P light, and continues to be incident on the fourth phase delay device 92 (electrically controlled 1 / 4 wave plate). The P light is again converted into right circularly polarized light, which is diffracted by the second lens 94, and is reconverted into S light by the fourth phase delay device 92 (electrically controlled 1 / 4 wave plate) and the third phase delay device 91 (electrically controlled 1 / 2 wave plate), and can directly transmit through the second grating 8 in the first optical waveguide 4 to enter the human eye 10.

[0053] Since the first lens 93 and the second lens 94 are both holographic optical elements with lens divergence function, but have different corresponding lens focal lengths, the coupled-out S light will converge at another specific distance to form a third focal plane viewed by the human eye 10.

[0054] When the times t1, t2 and t3 are within the range of the visual persistence time of the human eye 10, real-time display of three focal plane images can be realized, so that the human eye 10 can automatically focus at different positions, thereby effectively relieving the visual accommodation-vergence conflict problem of the human eye 10 and further improving the viewing comfort of the holographic optical waveguide AR display device.

[0055] The conversion of the polarization state of the incident light between the corresponding optical elements of the first polarization state image light processing device 7 and the second polarization state image light processing device 9 at times t2 and t3 is shown in Figures 2, 3, 4 and 5; the black dots in the figures represent S light, and the horizontal black double arrows represent P light.

[0056] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A multi-focal holographic optical waveguide display system, characterized in that, The polarization image light source, the first light waveguide, and the second light waveguide are provided; The first grating and the second grating are arranged between the first light waveguide and the second light waveguide; The first polarization state image light processing device and the second polarization state image light processing device are arranged on the side of the second light waveguide away from the first light waveguide; The first polarization state image light processing device comprises a first phase delay device, a second phase delay device, a third grating, and a fourth grating; The second polarization state image light processing device comprises a third phase delay device, a fourth phase delay device, a first lens, and a second lens; After the polarization image light source emits the first polarization light or the second polarization light, the first polarization light is diffracted in the first grating after passing through the first light waveguide, continues to reflect in the first light waveguide, and is output to the human eye to form an image after passing through the second grating and the first light waveguide, thereby obtaining a first focal plane; After the second polarization light is diffracted in the first grating, it passes through the second light waveguide, the first phase delay device, the second phase delay device, the third grating or the fourth grating, the second phase delay device, the first phase delay device, continues to reflect in the second light waveguide, and then passes through the third phase delay device, the fourth phase delay device, the first lens or the second lens, the fourth phase delay device, and the third phase delay device, is transmitted to the second grating through the second light waveguide, and is finally transmitted to the human eye through the first light waveguide. By adjusting the first phase delay device and the third phase delay device to perform phase delay with different preset angles on the second polarization light at the same time, the second polarization light at different times is output to the human eye through the second light waveguide to form an image, thereby obtaining a second focal plane and a third focal plane.

2. A multi-focal holographic optical waveguide display system according to claim 1, wherein, The first phase delay device and the third phase delay device are electrically controlled 1 / 2 wave plates, and the second phase delay device and the fourth phase delay device are electrically controlled 1 / 4 wave plates.

3. A multi-focal holographic optical waveguide display system according to claim 1, wherein, The third grating is a left-handed circularly polarized light response polarization volume holographic grating, the fourth grating is a right-handed circularly polarized light response polarization volume holographic grating, the first lens is a left-handed circularly polarized light response polarization volume holographic lens, and the second lens is a right-handed circularly polarized light response polarization volume holographic lens; The first polarization light is P light, which is diffracted in the first grating after passing through the first light waveguide, continues to reflect in the first light waveguide, and is output to the human eye to form an image after passing through the second grating and the first light waveguide, thereby obtaining a first focal plane; The second polarized light is S light, the first phase delay device and the third phase delay device are adjusted to perform phase delay of a first preset angle, so that the phase delay amount of the second polarized light is 0 phase, after the second polarized light is diffracted by the first grating, the second polarized light is sequentially reflected in the second optical waveguide, the first phase delay device, the second phase delay device, the third grating, the second phase delay device and the first phase delay device, and then the second polarized light is sequentially transmitted to the second grating through the third phase delay device, the fourth phase delay device, the first lens, the fourth phase delay device and the third phase delay device, and then the second polarized light is transmitted to the second optical waveguide, and finally the second polarized light is transmitted to the human eye through the first optical waveguide, the first phase delay device and the third phase delay device are adjusted to perform phase delay of different preset angles on the second polarized light, and then the second polarized light is output to the human eye through the second optical waveguide to form an image, and a second focal plane is obtained. The second polarized light is S light, the first phase delay device and the third phase delay device are adjusted to perform phase delay of a first preset angle, so that the phase delay amount of the second polarized light is Pi phase, after the second polarized light is diffracted by the first grating, the second polarized light is sequentially reflected in the second optical waveguide, the first phase delay device, the second phase delay device, the fourth grating, the second phase delay device and the first phase delay device, and then the second polarized light is sequentially transmitted to the second grating through the third phase delay device, the fourth phase delay device, the second lens, the fourth phase delay device and the third phase delay device, and then the second polarized light is transmitted to the second optical waveguide, and finally the second polarized light is transmitted to the human eye through the first optical waveguide, the first phase delay device and the third phase delay device are adjusted to perform phase delay of different preset angles on the second polarized light, and then the second polarized light is output to the human eye through the second optical waveguide to form an image, and a third focal plane is obtained.

4. A multi-focal holographic optical waveguide display system according to claim 1, wherein, The polarized image light source comprises a first polarized image light source and a second polarized image light source, the first polarized image light source is used to emit first polarized light, and the second polarized image light source is used to emit second polarized light.

5. A multifocal holographic optical waveguide display system according to claim 1, wherein, The first grating, the second grating, the third grating, the fourth grating, the first lens and the second lens are all reflective optical elements.

6. A multifocal holographic optical waveguide display system according to claim 1, wherein, The polarized image light source and the first optical waveguide are provided with an optical beam splitting device.

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