Hud display system based on retinal projection, three-dimensional image display method, and vehicle

Abstract

The application discloses a HUD display system based on retinal projection, a three-dimensional image display method and a vehicle, and belongs to the technical field of display products. The HUD display system comprises an image generation unit, which is used for generating a periodic left-handed polarization image and a right-handed polarization image; and a polarization volume holographic assembly, which comprises a left-handed polarization volume holographic element and a right-handed polarization volume holographic element arranged in layers. The left-handed polarization volume holographic element is used for receiving and diffracting the left-handed polarization image so that the left-handed polarization image converges to a first observation point. The right-handed polarization volume holographic element is used for receiving and diffracting the right-handed polarization image so that the right-handed polarization image converges to a second observation point. The application combines the retinal projection technology with the polarization volume holographic assembly, projects the parallax image signals into the human eyes without interference, and thus realizes three-dimensional display. The retinal projection technology has a large depth of field, and the human eyes can clearly see the image signals in a large depth range, so that the vergence accommodation conflict is avoided. Meanwhile, since the light path is simple and the optical system only comprises the image generation unit and the polarization volume holographic element, the volume and weight of the HUD display system are greatly reduced compared with mainstream schemes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of displaying products, and in particular to a HUD display system based on retinal projection, a three-dimensional image display method and a vehicle. BACKGROUND

[0002] A HUD (Head-Up Display) is an information display technology commonly used in cars, airplanes and other vehicles. The HUD display system projects information into the user's field of view, allowing the user to obtain key information without moving their attention away from the front. The HUD display system usually projects information onto the user's field of view through a transparent display screen or a reflector, so that the user can see the information on the HUD and the real-world scene at the same time. On a car, the HUD display system usually displays some basic driving information, such as speed, navigation instructions, vehicle warnings, etc.

[0003] In the related art, a patent with publication number CN108490613A discloses a head-up display device, a control method thereof and a vehicle. The head-up display device includes a display assembly, a first optical assembly, a second optical assembly and a combination assembly. The first optical assembly transmits or reflects light rays with different polarization directions or polarization states, separates the light rays for state information projection and augmented reality information projection, and thus realizes double-layer display. For example, augmented reality information can be displayed at a distance far from the driver's eyes, so that the focal length of the human eye does not need to be adjusted frequently during driving, making the viewing more comfortable, and thus eliminating safety hazards.

[0004] For the related art in the above, the principle is to make the first projection light and the second projection light enter the left and right eyes at the same time, and the first projection light and the second projection light carry different image information respectively, so that the left and right eyes can see different image information at the same time. However, in the above-mentioned scheme, there is a defect that three-dimensional display cannot be realized. SUMMARY

[0005] In order to facilitate the realization of three-dimensional display, the present application provides a HUD display system based on retinal projection, a three-dimensional image display method and a vehicle.

[0006] The HUD display system based on retinal projection provided by the present application adopts the following technical scheme:

[0007] In a first aspect,

[0008] A HUD display system based on retinal projection includes:

[0009] An image generation unit for generating periodic left-handed polarization images and right-handed polarization images;

[0010] A polarization volume holographic assembly includes a left-handed polarization volume holographic element and a right-handed polarization volume holographic element arranged in a stack, the left-handed polarization volume holographic element configured to receive and diffract the left-handed polarization image to converge the left-handed polarization image to a first observation point, and the right-handed polarization volume holographic element configured to receive and diffract the right-handed polarization image to converge the right-handed polarization image to a second observation point.

[0011] By using the above technical solution, the parallax image signals are projected into the human eyes without interfering with each other by using the retina projection technology and the polarization volume holographic assembly. Since the diffracted polarization image is the parallax image, three-dimensional display is realized. Meanwhile, the retina projection technology has a large depth of field, and the human eyes can clearly see the image signals in a large depth range, thereby avoiding the vergence accommodation conflict. Meanwhile, since the optical path is simple and the optical system only includes an image generation unit and a polarization volume holographic element, the volume and weight of the HUD display system are greatly reduced compared with mainstream solutions.

[0012] Optionally, the image generation unit includes:

[0013] a laser emitter configured to emit a linear light beam of red, green and blue colors;

[0014] a polarization element arranged in an optical path of the laser emitter and configured to convert the linear light beam emitted by the laser emitter into linearly polarized light;

[0015] an optical phase modulator arranged in an optical path of the polarization element, the optical phase modulator configured to convert the linearly polarized light into left-handed polarization light in a first phase state and into right-handed polarization light in a second phase state, and the first phase state and the second phase state being continuously switched; and

[0016] an image generation unit arranged in an optical path of the optical phase modulator, the image generation unit configured to scan the left-handed polarization light to form the left-handed polarization image and to scan the right-handed polarization light to form the right-handed polarization image.

[0017] By using the above technical solution, the retina projection display is based on the Maxwell observation method. Since the fine linear light beam (generated by the laser emitter) enters the human eyes, the human eyes can clearly see the image in a large depth of field. When the human eyes focus and the binocular convergence vergence observe natural real objects with different distances, the virtual image can be clearly displayed independently of the focusing of the lens, thereby avoiding the vergence accommodation conflict. The solution is combined with the polarization volume holographic element, which can solve the vergence accommodation conflict problem on the basis of 3D display, making the viewing more comfortable and eliminating safety hazards.

[0018] Optionally, the polarization volume holographic assembly is in a curved surface structure or a planar structure, or

[0019] The polarization volume holographic component can be switched between a curved structure or a planar structure.

[0020] By adopting the technical scheme, the shape of the polarization volume holographic component can be selected according to the interpupillary distance of each person to focus the left-handed and right-handed polarized images to the appropriate observation positions, so that the person can observe the clearest three-dimensional image.

[0021] Optionally, the polarization volume holographic component is a reflective or transmissive polarization volume holographic component.

[0022] By adopting the technical scheme, the position of the image generation unit is changed correspondingly by using different polarization volume holographic components, so that the volume occupation position of the HUD display system can be adjusted according to the actual situation.

[0023] Optionally, the optical phase modulator is an electrically controlled liquid crystal 1 / 4 wave plate.

[0024] By adopting the technical scheme, the electrically controlled liquid crystal 1 / 4 wave plate has a first phase state and a second phase state that can be switched to each other, when in the first phase state, the electrically controlled liquid crystal 1 / 4 wave plate can convert linearly polarized light into left-handed polarized light, when in the second phase state, the electrically controlled liquid crystal 1 / 4 wave plate can convert linearly polarized light into right-handed polarized light, the two phase states are switched at a certain frequency, so that the linearly polarized light is divided into left-handed polarized light and right-handed polarized light after passing through the electrically controlled liquid crystal 1 / 4 wave plate, and the light beam emitted from the electrically controlled liquid crystal 1 / 4 wave plate is composed of left-handed polarized light and right-handed polarized light, which lays a foundation for the formation of subsequent two-dimensional images.

[0025] Optionally, the left-handed polarization volume holographic element and the right-handed polarization volume holographic element are both non-periodic structures.

[0026] By adopting the technical scheme, the non-periodic structure has a wider wavelength range performance, can diffract a wider wavelength range, and can reduce scattering effects during diffraction to improve the performance of the element.

[0027] Optionally, the position of the image generation unit relative to the polarization volume holographic component is adjustable.

[0028] By adopting the technical scheme, the positions of the first observation point and the second observation point can be changed, so that the person can see the display of the three-dimensional image at different observation points, and the adaptability is improved.

[0029] The left-handed polarization volume holographic element can diffract left-handed polarization light and has no effect on right-handed polarization light, and the right-handed polarization volume holographic element can diffract right-handed polarization light and has no effect on left-handed polarization light. In this way, left-handed polarization light and right-handed polarization light with different two-dimensional images are diffracted to different eyes, so as to form a stereoscopic effect. In addition, diffracting left-handed polarization light and right-handed polarization light to the eyes can help to avoid interference or cross images.

[0030] The second aspect,

[0031] A three-dimensional image display method, comprising:

[0032] Providing an image generation unit, so that the image generation unit generates periodic left-handed polarization images and right-handed polarization images; and

[0033] Providing a polarization volume holographic assembly, the polarization volume holographic assembly comprising left-handed polarization volume holographic elements and right-handed polarization volume holographic elements arranged in layers, the left-handed polarization volume holographic elements being used to receive and diffract the left-handed polarization images so that the left-handed polarization images converge to a first observation point, and the right-handed polarization volume holographic elements being used to receive and diffract the right-handed polarization images so that the right-handed polarization images converge to a second observation point.

[0034] By adopting the above technical solution, parallax images are provided for the first observation point and the second observation point, so that depth information is provided for the first observation point and the second observation point, and three-dimensional stereoscopic display is realized.

[0035] Optionally, the first observation point is a first eye point, and the second observation point is a second eye point.

[0036] By adopting the above technical solution, the first eye point and the second eye point correspond to the eyes of a person respectively, so that the eyes can observe different depth information, and three-dimensional image display is realized.

[0037] The third aspect,

[0038] A vehicle comprising a windshield and the above-mentioned HUD display system based on retinal projection, the polarization volume holographic assembly being arranged on the windshield.

[0039] By adopting the above technical solution, the driver can observe external information through the windshield and also observe vehicle state information such as vehicle speed, oil temperature, etc. through the holographic element, so as to improve the convenience and safety of driving.

[0040] In summary, the present application has at least one of the following beneficial technical effects:

[0041] 1. The application uses retinal projection technology combined with polarization volume holographic components to project parallax image signals into the human eye without interference. Since the diffracted polarization image is a parallax image, three-dimensional display is achieved. At the same time, the retinal projection technology has a large depth of field, and the human eye can clearly see the image signal in a large depth range, thus avoiding the vergence accommodation conflict. At the same time, due to the simple optical path, the optical system only includes an image generation unit and a polarization volume holographic element, and the volume and weight of the HUD display system are greatly reduced compared to mainstream solutions.

[0042] 2. The scheme is combined with a polarization volume holographic element, which can solve the vergence accommodation conflict problem on the basis of 3D display, making the viewing more comfortable and eliminating safety hazards.

[0043] 3. The positions of the first observation point and the second observation point can be changed, so that personnel at different observation points can see three-dimensional image display, improving its adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a structural schematic diagram of the HUD display system of the application.

[0045] Figure 2 is a structural schematic diagram of the polarization volume holographic component of the HUD display system of the application.

[0046] Figure 3 is a schematic diagram of the polarization volume holographic component attached to the windshield.

[0047] BRIEF DESCRIPTION OF DRAWINGS

[0048] 100, laser emitter; 200, polarization element; 201, linearly polarized light; 300, optical phase modulator; 400, image generation unit; 401, diverging spherical beam; 500, polarization volume holographic component; 510, left-handed polarization volume holographic element; 511, first converging spherical beam; 520, right-handed polarization volume holographic element; 521, second converging spherical beam; 610, first observation point; 620, second observation point; 700, windshield. DETAILED DESCRIPTION

[0049] The following will be described in detail in combination with the accompanying drawings Figures 1-3 The application will be further described in detail.

[0050] In the related art, vergence is the function of the eyes to maintain a single perspective by means of adduction (convergence) and abduction (divergence). The vergence function converges the lines of sight of the eyes on the same object, while the accommodation function focuses on the same object at the same distance. Over time, the brain has become accustomed to the rule that the line of sight and the focus point are always in the same place. However, when watching a 3D movie, the distance between the viewer and the screen is constant, so the focal length cannot change. This causes the accommodation function to be unable to focus on the same distance as the vergence function as in daily life. In turn, this breaks the long-standing rule, causing the vergence and accommodation to be separated, which is the vergence-accommodation conflict.

[0051] Embodiments of the present application disclose a HUD display system based on retinal projection. Referring to Figure 1 The HUD display system comprises an image generation unit and a polarization volume holographic assembly 500 arranged in sequence along the propagation direction of the light path. The image generation unit is configured to generate periodic left-handed polarization images and right-handed polarization images. The polarization volume holographic assembly 500 comprises left-handed polarization volume holographic elements 510 and right-handed polarization volume holographic elements 520 arranged in layers. The left-handed polarization volume holographic elements 510 are configured to receive and diffract the left-handed polarization images to converge the left-handed polarization images to a first observation point 610. The right-handed polarization volume holographic elements 520 are configured to receive and diffract the right-handed polarization images to converge the right-handed polarization images to a second observation point 620.

[0052] In a preferred embodiment, the image generation unit comprises a laser emitter 100, a polarization element 200, an optical phase modulator 300 and a scanning galvanometer 400 arranged in sequence along the propagation direction of the light path.

[0053] The laser emitter 100 emits a linear light beam. The polarization element 200 converts the linear light beam emitted by the laser emitter 100 into linearly polarized light 201. The optical phase modulator 300 converts the linearly polarized light 201 into left-handed polarization light and right-handed polarization light. The scanning galvanometer 400 scans the left-handed polarization light and the right-handed polarization light to form left-handed polarization images and right-handed polarization images. The left-handed polarization volume holographic elements 510 receive and diffract the left-handed polarization images to converge the left-handed polarization images to the first observation point 610. The right-handed polarization volume holographic elements 520 receive and diffract the right-handed polarization images to converge the right-handed polarization images to the second observation point 620. Since the left-handed polarization images and the right-handed polarization images are parallax images, the polarization images carry depth information, so that a three-dimensional stereoscopic image is observed at the observation point.

[0054] In one embodiment, the laser emitter 100 comprises a red light chip, a green light chip and a blue light chip, which respectively emit red light, green light and blue light. The three kinds of light form a color image light with depth of field after modulation, and enter the left and right eyes of a person, so that the image observed by the person's eyes is a three-dimensional color image. In other embodiments, the laser emitter 100 can also be a solid laser, a gas laser or a semiconductor laser, etc.

[0055] With reference to Figure 1 The polarization element 200 is one of a polarizer, a polarization beam splitter, a polarization prism and a full wave plate. Preferably, the polarization element 200 is a polarizer, which can reduce the light reflected or refracted back from the surface by selecting the polarized light in a specific direction, and improve the transmittance. Moreover, the polarizer has small volume and low price. The linear light beam becomes linearly polarized light 201 after passing through the polarization element 200.

[0056] In a preferred embodiment, the optical phase modulator 300 is an electrically controlled liquid crystal 1 / 4 wave plate, which has a first phase state and a second phase state capable of being switched to each other. When in the first phase state, the electrically controlled liquid crystal 1 / 4 wave plate converts the linearly polarized light 201 into left-handed polarized light, and when in the second phase state, the electrically controlled liquid crystal 1 / 4 wave plate converts the linearly polarized light into right-handed polarized light. The two phase states are switched at a certain frequency, and the switching frequency of the two phase states is greater than or equal to 30 Hz, which is the minimum refresh frequency of the human eye. The linearly polarized light 201 is divided into left-handed polarized light and right-handed polarized light after passing through the electrically controlled liquid crystal 1 / 4 wave plate, and the light beam emitted from the electrically controlled liquid crystal 1 / 4 wave plate is composed of left-handed polarized light and right-handed polarized light.

[0057] Specifically, if the frequency of the image signal carried by the linearly polarized light 201 is 120 Hz, and the switching frequency of the electrically controlled liquid crystal 1 / 4 wave plate in the two phase states is 60 Hz, then the frequency of the image signal carried by the left-handed polarized light and the right-handed polarized light is 60 Hz.

[0058] In other embodiments, the optical phase modulator 300 can also be a liquid crystal modulator, or other optical phase modulators 300 capable of converting the linearly polarized light 201 into left-handed polarized light and right-handed polarized light, which are all within the protection scope of the present application.

[0059] In a preferred embodiment, the scanning mirror 400 is a two-dimensional scanning mirror, which can rotate controllably in horizontal and vertical directions, and the left-circularly polarized light and the right-circularly polarized light are reflected by the two-dimensional scanning mirror 400 to form a divergent spherical light beam 401, so as to construct a two-dimensional image. That is, the left-circularly polarized light and the right-circularly polarized light are reflected by the two-dimensional scanning mirror 400 to form a left-circularly polarized image and a right-circularly polarized image respectively, and the left-circularly polarized image and the right-circularly polarized image are diffracted by the left-circularly polarized volume holographic element 510 and the right-circularly polarized volume holographic element 520 to enter the human eye.

[0060] In other embodiments, the scanning mirror 400 can also be an optical lens array or a spatial light modulator (LCOS) and the like.

[0061] In the embodiment, the left-circularly polarized volume holographic element 510 can diffract the left-circularly polarized image and has no effect on the right-circularly polarized image, and the right-circularly polarized volume holographic element 520 can diffract the right-circularly polarized image and has no effect on the left-circularly polarized image.

[0062] Therefore, the diffracted left-circularly polarized light enters the first observation point 610, and the diffracted right-circularly polarized light enters the second observation point 620. In the embodiment, the first observation point 610 is a first eye point, and the second observation point 620 is a second eye point. The first eye point is the position of the left pupil of the human eye, and the second eye point is the position of the right pupil of the human eye. The diffracted left-circularly polarized image is a first convergent spherical light beam 511, and the convergent point of the first convergent spherical light beam 511 is the first eye point. The diffracted right-circularly polarized image is a second convergent spherical light beam 521, and the convergent point of the second convergent spherical light beam 521 is the second eye point.

[0063] In this way, the left eye of the human eye receives the left-circularly polarized image, and the right eye of the human eye receives the right-circularly polarized image. The left-circularly polarized image and the right-circularly polarized image respectively carry two two-dimensional images, one of which enters the left eye, and the other of which enters the right eye. Since the two two-dimensional images are parallax images carrying depth information, the human eye can see a three-dimensional image. At the same time, since the light beam has a large depth of field, the human eye can clearly see the image signal in a large depth range, so as to avoid the vergence accommodation conflict.

[0064] In the embodiment, the polarization volume holographic assembly 500 is a reflective or transmissive polarization volume holographic assembly, and the polarization volume holographic assembly 500 is a curved surface structure or a planar structure and can be switched between the curved surface structure and the planar structure. Figure 1 In the embodiment, the polarization volume holographic assembly 500 is a reflective polarization volume holographic assembly, and the polarization volume holographic assembly 500 is a curved surface structure. The left-circularly polarized image and the right-circularly polarized image are diffracted by the reflective polarization volume holographic assembly 500 to enter the human eye.

[0065] In other embodiments, the polarization volume holographic assembly 500 is a transmissive polarization volume holographic assembly, and the polarization volume holographic assembly 500 is a planar structure. The left-circularly polarized image and the right-circularly polarized image are diffracted by the transmissive polarization volume holographic assembly 500 to enter the human eye.Figure 2 The polarization volume holographic component 500 is a transmission type polarization volume holographic component, and the left-handed polarization image and the right-handed polarization image are diffracted by the transmission type polarization volume holographic component 500 and enter the human eyes.

[0066] In other embodiments, the polarization volume holographic component 500 can also be a planar structure, and the polarization volume holographic component 500 can be switched between the curved structure and the planar structure, and the switching can be performed by a thermo-optic modulation. The thermo-optic modulation uses the photothermal effect to adjust the surface shape by heating or cooling different regions of the polarization volume holographic component 500. This method can locally change the optical properties of the material, thereby realizing the switching between the planar structure and the curved structure. Such a setting can select a suitable shape of the polarization volume holographic component 500 according to the interpupillary distance of each person to focus the left-handed polarization image and the right-handed polarization image to a suitable observation position, so that the human eyes can observe the clearest three-dimensional image.

[0067] Meanwhile, the left-handed polarization volume holographic element 510 and the right-handed polarization volume holographic element 520 are both non-periodic structures, and the non-periodic structure has a wider wavelength range performance, can diffract a wider wavelength range, and can reduce the scattering effect during the diffraction process and improve the utilization rate of image light.

[0068] In addition, the position of the image generation unit relative to the polarization volume holographic component 500 is adjustable. The image generation unit can be controllably rotated in the horizontal direction and the vertical direction, so that the position of the polarization volume holographic component 500 relative to the image generation unit changes. At this time, by controlling the movement of the image generation unit, the polarization volume holographic component 500 diffracts the image to different observation points, so that the human eyes can see three-dimensional images at different observation points.

[0069] In other embodiments, the HUD display system further includes a visual tracking system, which determines the position of the human eyes and adjusts the position of the image generation unit, so that the image diffracted by the polarization volume holographic component 500 falls into the human eyes.

[0070] The implementation principle of the HUD display system based on retinal projection according to the embodiments of the present application is as follows: the HUD display system includes an image generation unit and a polarization volume holographic component 500. The image generation unit generates a left-handed polarization image and a right-handed polarization image in time sequence control. The left-handed polarization image and the right-handed polarization image are both two-dimensional images, and the two two-dimensional images enter the left eye and the right eye, respectively. Since the two two-dimensional images are parallax images carrying depth information, the human eyes can see a three-dimensional image. Meanwhile, the optical system of the present application only includes the image generation unit and the polarization volume holographic component 500, the optical path is simple, and the volume and weight of the HUD display system are greatly reduced compared with mainstream solutions.

[0071] The embodiment of the present application further discloses a three-dimensional image display method, comprising:

[0072] The image generation unit is provided to generate the periodic left-handed polarized image and the right-handed polarized image; and

[0073] The polarized volume holographic assembly 500 comprises a left-handed polarized volume holographic element 510 and a right-handed polarized volume holographic element 520 arranged in a stack, the left-handed polarized image is received and diffracted by the left-handed polarized volume holographic element 510 so as to converge to a first observation point 610, and the right-handed polarized image is received and diffracted by the right-handed polarized volume holographic element 520 so as to converge to a second observation point 620. The first observation point 610 is a first eye point, and the second observation point 620 is a second eye point.

[0074] The embodiment of the present application further discloses a vehicle, referring to Figure 3 , comprising a windshield 700 and the HUD display system based on the retinal projection, and the polarized volume holographic assembly 500 is arranged on the windshield 700.

[0075] In the embodiment, the windshield 700 is a curved windshield. In other embodiments, the windshield 700 can be an automobile windshield, a train windshield, an aircraft windshield, etc.

[0076] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A retinal projection based HUD display system, characterized by, Comprising: an image generating unit for generating periodic left-handed polarized images and right-handed polarized images; a polarization volume holographic assembly (500) comprising a left-handed polarization volume holographic element (510) and a right-handed polarization volume holographic element (520) arranged in a stack, the left-handed polarization volume holographic element (510) being configured to receive and diffract the left-handed polarized images to converge the left-handed polarized images to a first observation point (610), the right-handed polarization volume holographic element (520) being configured to receive and diffract the right-handed polarized images to converge the right-handed polarized images to a second observation point (620); the image generating unit comprising: a laser emitter (100) configured to emit a linear light beam of red, green and blue colors; a polarization element (200) arranged in an optical path of the laser emitter (100) and configured to convert the linear light beam emitted by the laser emitter (100) into linearly polarized light (201); an optical phase modulator (300) arranged in an optical path of the polarization element (200), the optical phase modulator (300) being configured to convert the linearly polarized light (201) into left-handed polarized light in a first phase state and into right-handed polarized light in a second phase state, the first phase state and the second phase state being switched continuously; and a scanning galvanometer (400) arranged in an optical path of the optical phase modulator (300), the scanning galvanometer (400) being configured to scan the left-handed polarized light to form the left-handed polarized images and to scan the right-handed polarized light to form the right-handed polarized images, the left-handed polarized light and the right-handed polarized light being reflected by the scanning galvanometer (400) to form a divergent spherical light beam (401) propagating along the same optical path, the left-handed polarization volume holographic element (510) and the right-handed polarization volume holographic element (520) being non-periodic structures.

2. The retinal projection-based HUD display system of claim 1, wherein: the polarization volume holographic assembly (500) is a curved surface structure or a planar structure, or the polarization volume holographic assembly (500) is switchable between a curved surface structure and a planar structure.

3. The retinal projection-based HUD display system of claim 1, wherein: the polarization volume holographic assembly (500) is a reflective polarization volume holographic assembly or a transmissive polarization volume holographic assembly.

4. The retinal projection-based HUD display system of claim 1, wherein: the optical phase modulator (300) is an electrically controlled liquid crystal 1 / 4 wave plate.

5. The retinal projection-based HUD display system of claim 1, wherein: the image generating unit is adjustable relative to the polarization volume holographic assembly (500).

6. A three-dimensional image display method characterized by Comprising: providing an image generating unit, the image generating unit being configured to generate periodic left-handed polarized images and right-handed polarized images, the image generating unit comprising: a laser emitter (100) configured to emit a linear light beam of red, green and blue colors; a polarization element (200) arranged in an optical path of the laser emitter (100) and configured to convert the linear light beam emitted by the laser emitter (100) into linearly polarized light (201); An optical phase modulator (300) is arranged in the light path of the polarizing element (200), the optical phase modulator (300) is used to convert the linearly polarized light (201) into left-handed polarized light in a first phase state and convert the linearly polarized light (201) into right-handed polarized light in a second phase state, and the first phase state and the second phase state are continuously switched; A scanning galvanometer (400) is arranged in the light path of the optical phase modulator (300), the scanning galvanometer (400) is used to scan the left-handed polarized light to form the left-handed polarized image and scan the right-handed polarized light to form the right-handed polarized image, and the left-handed polarized light and the right-handed polarized light are reflected by the scanning galvanometer (400) to form a divergent spherical light beam (401) transmitted along the same light path; A polarization volume holographic assembly (500) is provided, the polarization volume holographic assembly (500) comprises a left-handed polarization volume holographic element (510) and a right-handed polarization volume holographic element (520) arranged in layers, the left-handed polarization volume holographic element (510) is used to receive and diffract the left-handed polarized image to converge the left-handed polarized image to a first observation point (610), and the right-handed polarization volume holographic element (520) is used to receive and diffract the right-handed polarized image to converge the right-handed polarized image to a second observation point (620); the left-handed polarization volume holographic element (510) and the right-handed polarization volume holographic element (520) are both non-periodic structures.

7. The three-dimensional image display method according to claim 6, wherein The first observation point (610) is a first eye point, and the second observation point (620) is a second eye point.

8. A vehicle characterized by comprising: The HUD display system based on retinal projection comprises a windshield (700) and the HUD display system based on retinal projection of any one of claims 1-5, and the polarization volume holographic assembly (500) is arranged on the windshield (700).

Images