Near-eye display system and display method based on retinal projection

Abstract

The application discloses a near-eye display system and a display method based on retinal projection, and belongs to the technical field of display products. The near-eye display system comprises an image generation unit, a waveguide device, a second phase element and a second polarization volume holographic element. The image generation unit is used for generating an imaging beam with image information. The waveguide device is used for receiving the imaging beam of the image generation unit and performing optical path folding on the imaging beam. The second phase element selectively converts the imaging beam into first polarized light or second polarized light. The second polarization volume holographic element is used for receiving the first polarized light or the second polarized light emitted by the second phase element. The second phase element selectively converts the first polarized light or the second polarized light to converge the first polarized light or the second polarized light to different view points through the second polarization volume holographic element. The application can increase the eye movement range and avoid image crosstalk and dark area phenomenon under the premise of solving the vergence accommodation conflict problem.

Description

Technical Field

[0001] This application relates to the technical field of display products, and in particular to a near-eye display system and display method based on retinal projection. Background Technology

[0002] Vergence-accommodation conflict (VAC) is a common problem in augmented reality (AR) and virtual reality (VR) technologies. It refers to the incoordination between convergence (the inward or outward rotation of the eyes to align with a target) and accommodation (the lens changing shape to focus on objects at different distances) when the human eye observes virtual objects. Normally, convergence and accommodation occur synchronously when a person observes an object. However, in AR and VR devices, because the screen is flat and lacks actual depth information, this mismatch between the eye's focusing accommodation and convergence causes a conflict, resulting in visual discomfort and dizziness.

[0003] Retinal projection displays are based on Maxwell's observation method. Because a narrow beam of light enters the eye, the eye can clearly see the image over a large depth range. When the eye focuses and the binoculars converge to observe natural objects at different distances, the virtual image can be clearly displayed independently of the lens's focusing, thus resolving the convergence-accommodation conflict.

[0004] However, in existing retinal projection technology, the convergence point of the thin beam needs to match the human eye's pupil, thus limiting the range of eye movement. Furthermore, existing pupil dilation methods often involve multiple viewpoints simultaneously, leading to image crosstalk or dark areas. Summary of the Invention

[0005] In order to increase the eye movement range and avoid image crosstalk and dark area phenomena while solving the convergence-accommodation conflict problem, this application provides a near-eye display system and display method based on retinal projection.

[0006] The near-eye display system based on retinal projection provided in this application adopts the following technical solution:

[0007] First aspect

[0008] A near-eye display system based on retinal projection, comprising:

[0009] An image generation unit is used to generate an imaging beam with image information;

[0010] A waveguide device is used to receive the imaging beam from the image generation unit and to fold the imaging beam in an optical path.

[0011] The second phase element is used to receive the imaging beam after optical path folding and selectively convert the imaging beam into first polarized light or second polarized light, wherein the polarization states of the first polarized light and the second polarized light are orthogonal.

[0012] A secondary polarizing holographic element is used to receive first polarized light or second polarized light emitted from the second phase element. The secondary polarizing holographic element includes a third polarizing diffraction element and a fourth polarizing diffraction element stacked together. The third polarizing diffraction element diffracts the first polarized light and transmits the second polarized light, and the fourth polarizing diffraction element diffracts the second polarized light and transmits the first polarized light.

[0013] The second phase element selectively transforms the first polarized light or the second polarized light to converge the first polarized light or the second polarized light to different viewpoints through the secondary polarizer holographic element.

[0014] By employing the above technical solution, this invention uses a polarization-selective holographic element to diffract an image beam, causing the beam to converge and form a viewpoint that enters the pupil of the human eye. A second phase element is used to change the polarization state of the image beam, allowing it to selectively diffract or transmit through different polarization holographic elements, thus forming different eyepoints. This expands the eyebox of the system, and only one eyepoint is formed per time period. Different eyepoints do not interfere with each other, thereby avoiding image crosstalk and dark area phenomena, and improving the user experience.

[0015] Optionally, the image generation unit for generating an imaging beam with image information includes:

[0016] The image generation unit is used to selectively generate first polarized light or second polarized light with image information, and the first polarized light or second polarized light is incident on the waveguide device.

[0017] The near-eye display system also includes:

[0018] A primary polarizing holographic element is used to receive first polarized light or second polarized light generated by an image generation unit. The primary polarizing holographic element includes a first polarization diffraction element and a second polarization diffraction element stacked together. The first polarization diffraction element diffracts the first polarized light and transmits the second polarized light, and the second polarization diffraction element diffracts the second polarized light and transmits the first polarized light.

[0019] The first polarized light or the second polarized light diffracted by the first-stage polarizing holographic element is incident into the waveguide device.

[0020] By adopting the above technical solution and adjusting the polarization state of the beam in real time, dynamic viewpoint switching is achieved, further expanding the eye box range of the system and solving the problem of small eye movement range in traditional retinal projection technology.

[0021] Optionally, the image generation unit includes:

[0022] A laser emitter used to emit a line beam composed of red, green, and blue modulated light.

[0023] A polarization element is disposed in the output optical path of the laser emitter to convert the linear beam emitted by the laser emitter into linearly polarized light;

[0024] An optical phase modulator, disposed in the light output path of the polarization element, selectively converts the linearly polarized light into either first polarized light or second polarized light; and

[0025] A scanning galvanometer is disposed on the output light path of the optical phase modulator. The scanning galvanometer is used to scan the first polarized light or the second polarized light to convert the first polarized light or the second polarized light into a diverging spherical beam.

[0026] By adopting the above technical solution, the laser emitter generates a thin beam, effectively solving the problem of convergence adjustment conflict. The optical phase modulator and the first-order polarizer holographic element work together to further expand the eye movement range and solve the problem of small eye movement range in retinal projection technology.

[0027] Optionally, the optical phase modulator includes a first phase element and an electrically controlled half-wave plate arranged sequentially along the optical path transmission direction. The first phase element is used to convert linearly polarized light into first polarized light, and the electrically controlled half-wave plate has an on / off state to convert the first polarized light into second polarized light or not convert the first polarized light, or...

[0028] The first phase element is used to convert linearly polarized light into second polarized light, and the electrically controlled half-wave plate has an on / off state to convert the second polarized light into first polarized light or not convert the second polarized light.

[0029] By adopting the above technical solution, this design not only improves the flexibility of the system, but also ensures that the imaging beam can be precisely switched under different polarization states, thereby achieving fast and accurate switching between different viewpoints, further expanding the field of view of the system, and reducing image crosstalk and dark area phenomena.

[0030] Optionally, the near-eye display system further includes an eye-tracking device, wherein the second phase element has an on / off state to convert the imaging beam into first polarized light or second polarized light, and the eye-tracking device is signal-connected to the second phase element and the electronically controlled half-wave plate.

[0031] Optionally, the eye-tracking device can monitor the position of the pupil in real time and adjust the operating state of the second phase element and the electrically controlled half-wave plate according to the pupil position, ensuring that the imaging beam is converted to the required polarization state at the correct time, thereby converging the image beam to the correct eye point. This not only expands the effective eye box range of the system, but also avoids image crosstalk and dark area phenomena caused by multiple viewpoints existing simultaneously, improving the user experience.

[0032] Optionally, the near-eye display system further includes an eye-tracking device, wherein the second phase element has an on / off state to convert the imaging beam into first polarized light or second polarized light, and the eye-tracking device is signal-connected to the second phase element.

[0033] By adopting the above technical solution, the function of dynamically adjusting the viewpoint position is realized, effectively expanding the system's field of view and eyebox range. The eye-tracking device can monitor the changes in the pupil position in real time and control the opening and closing state of the second phase element according to the changes in pupil position, thereby causing the imaging beam to alternate between different polarization states, ensuring that the human eye can always receive a clear image. This design not only solves the problem of small eyebox range in traditional retinal projection technology, but also avoids image crosstalk and dark area phenomena caused by multiple viewpoints coexisting, significantly improving the user experience.

[0034] Optionally, the secondary polarizer holographic element is covered on the surface of the waveguide device or embedded in the waveguide device.

[0035] By adopting the above technical solution, the secondary polarizer holographic element can be overlaid on the surface of the waveguide device or embedded in the waveguide device, which can effectively reduce optical path loss, improve optical efficiency, simplify the system's structural design, and reduce manufacturing costs. Furthermore, this integrated design can also improve the system's stability and reliability, ensuring normal operation in various environments.

[0036] Second aspect

[0037] A near-eye display method based on retinal projection includes the following steps:

[0038] Generate an imaging beam containing image information;

[0039] Receive the imaging beam and fold the imaging beam in the optical path;

[0040] It receives the imaging beam after optical path folding and selectively converts the imaging beam into first polarized light or second polarized light, wherein the polarization states of the first polarized light and the second polarized light are orthogonal.

[0041] A secondary polarization holographic element is provided, comprising a third polarization diffraction element and a fourth polarization diffraction element stacked together. The third polarization diffraction element diffracts first polarized light and transmits second polarized light, while the fourth polarization diffraction element diffracts second polarized light and transmits first polarized light, so as to converge the first polarized light or the second polarized light to different viewpoints.

[0042] By adopting the above technical solution, the eye-tracking range of retinal projection technology can be effectively increased, solving the problem of limited eye movement range in traditional retinal projection technology. Simultaneously, this method selectively converts the imaging beam into either first-polarized or second-polarized light, and utilizes a secondary polarizer holographic element to converge the beam to different viewpoints, ensuring that no single viewpoint exists simultaneously. This avoids image crosstalk and dark areas, improving the user experience.

[0043] Optionally, the step of generating the imaging beam with image information includes:

[0044] Selectively generate either first-polarized light or second-polarized light carrying image information;

[0045] Before the step of receiving the imaging beam and performing optical path folding on the imaging beam, the method further includes:

[0046] A primary polarizing holographic element is provided. The primary polarizing holographic element is used to receive first polarized light or second polarized light carrying image information. The primary polarizing holographic element includes a first polarization diffraction element and a second polarization diffraction element stacked together. The first polarization diffraction element diffracts the first polarized light and transmits the second polarized light. The second polarization diffraction element diffracts the second polarized light and transmits the first polarized light. The optical path of the diffracted first polarized light or second polarized light is folded.

[0047] By employing the above technical solution, selective diffraction and transmission of first and second polarized light can be achieved through a first-order polarizing holographic element during retinal projection display, further optimizing the optical path folding process. This not only ensures the effective transmission of the image beam but also improves the stability and reliability of the system. Specifically, the combined use of the first and second polarization diffraction elements enables precise control of beams with different polarization states, effectively expanding the eyebox range of the system, avoiding image crosstalk and dark area phenomena, and enhancing the user's visual experience.

[0048] Optionally, the following steps may also be included:

[0049] An eye-tracking device is provided, which tracks the position of the pupil in real time and converts the imaging beam into first polarized light or second polarized light according to the position of the pupil.

[0050] By adopting the above technical solution, the eye-tracking device can track the position of the pupil in real time and dynamically adjust the polarization state of the imaging beam according to the pupil position, ensuring that the image beam always converges at the current position of the human eye, effectively expanding the system's field of view and improving the comfort of the user experience.

[0051] In summary, this application includes at least one of the following beneficial technical effects:

[0052] 1. This invention uses a polarization-selective holographic element to diffract an image beam, causing the beam to converge and form a viewpoint that enters the pupil of the human eye. A second phase element is used to change the polarization state of the image beam, allowing it to selectively diffract or transmit through different polarization holographic elements, thus forming different eyepoints. This expands the eyebox of the system, and only one eyepoint is formed per time period. Different eyepoints do not interfere with each other, thus avoiding image crosstalk and dark areas, and improving the user experience.

[0053] 2. By adjusting the polarization state of the beam in real time, dynamic viewpoint switching is achieved, further expanding the eye box range of the system and solving the problem of small eye movement range in traditional retinal projection technology.

[0054] 3. The laser emitter generates a narrow beam, effectively solving the problem of convergence and accommodation conflict. The optical phase modulator and the first-order polarizer holographic element work together to further expand the eye movement range and solve the problem of small eye movement range in retinal projection technology.

[0055] 4. The eye-tracking device can monitor the position of the pupil in real time and adjust the working state of the second phase element and the electronically controlled half-wave plate according to the pupil position. This ensures that the imaging beam is converted to the required polarization state at the correct time, thereby converging the image beam to the correct eye point. This not only expands the effective eye box range of the system but also avoids image crosstalk and dark area phenomena caused by multiple viewpoints existing simultaneously, improving the user experience. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of a near-eye display system based on retinal projection provided in a specific embodiment of this application (the dashed lines in the figure indicate the direction of the light path);

[0057] Figure 2 This is a schematic diagram of a near-eye display system based on retinal projection provided in another specific embodiment of this application (the dashed line in the figure indicates the direction of the light path).

[0058] Explanation of reference numerals in the attached figures:

[0059] 10. Image generation unit; 11. Laser emitter; 12. Polarization element; 13. Optical phase modulator; 131. First phase element; 132. Electrically controlled half-wave plate; 14. Scanning galvanometer; 20. Waveguide device; 30. First-order polarizing holographic element; 31. First polarization diffraction element; 32. Second polarization diffraction element; 40. Second phase element; 50. Second-order polarizing holographic element; 51. Third polarization diffraction element; 52. Fourth polarization diffraction element; 60. Eye tracking device; 70. First eye point; 71. Second eye point; 72. Third eye point; 73. Fourth eye point. Detailed Implementation

[0060] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0061] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only possible technical implementations of the present invention and not all possible implementations. Those skilled in the art can obtain other embodiments in conjunction with the embodiments of the present invention without creative effort, and these embodiments are also within the protection scope of the present invention.

[0062] The inventors of this application discovered that mainstream augmented reality optical display schemes cause convergence-accommodation conflict in the human eye. Retinal projection displays can resolve this conflict, but their range of eye movement is very small. Therefore, this application mainly adopts the following near-eye display system based on retinal projection, which achieves the effect of expanding the range of eye movement. The following is a further detailed description of this application.

[0063] Example 1

[0064] The near-eye display system based on retinal projection provided in this application embodiment refers to... Figure 1In one embodiment, the near-eye display system includes an image generation unit 10, a waveguide device 20, a coupling element (not shown), a second phase element 40, and a secondary polarizer holographic element 50. The image generation unit 10 generates an imaging beam carrying image information; the coupling element couples the imaging beam from the image generation unit 10 into the waveguide device 20, which receives the imaging beam and performs optical path folding; the second phase element 40 receives the optically folded imaging beam and selectively converts it into first polarized light or second polarized light, the polarization states of which are orthogonal; the secondary polarizer holographic element 50 receives the first polarized light or second polarized light emitted from the second phase element 40, and includes a stacked third polarization diffraction element 51 and a fourth polarization diffraction element 52. The third polarization diffraction element 51 diffracts the first polarized light and transmits the second polarized light, while the fourth polarization diffraction element 52 diffracts the second polarized light and transmits the first polarized light. By selectively changing the first polarized light or the second polarized light through the second phase element 40, the first polarized light or the second polarized light is converged to two different viewpoints through the secondary polarizer holographic element 50, thereby expanding the eye movement range.

[0065] Reference Figure 2 In another preferred embodiment, the image generation unit 10 selectively generates first polarized light or second polarized light carrying image information. The first polarized light or second polarized light is incident on the waveguide device 20, and the coupling element is a first-stage polarizing holographic element 30. The first-stage polarizing holographic element 30 receives the first polarized light or second polarized light generated by the image generation unit 10. The first-stage polarizing holographic element 30 includes a first polarization diffraction element 31 and a second polarization diffraction element 32 stacked together. The first polarization diffraction element 31 diffracts the first polarized light and transmits the second polarized light, while the second polarization diffraction element 32 diffracts the second polarized light and transmits the first polarized light. By selectively generating the first polarized light or second polarized light by the image generation unit 10 and selectively transforming the first polarized light or second polarized light by the second phase element 40, the first polarized light or second polarized light is converged to four different viewpoints by the second-stage polarizing holographic element 50, further expanding the eye-tracking range. In other embodiments, the eye-tracking range can also be further expanded by increasing the number of polarizing holographic elements or by other means. In addition, the coupling element can also be a geometric element, a surface relief diffraction element, etc.

[0066] Reference Figure 2Specifically, the image generation unit 10 includes a laser emitter 11, a polarization element 12, an optical phase modulator 13, and a scanning mirror 14. The laser emitter 11 emits a line beam composed of red, green, and blue modulated light; the polarization element 12 is disposed in the output optical path of the laser emitter 11 to convert the line beam emitted by the laser emitter 11 into linearly polarized light; the optical phase modulator 13 is disposed in the output optical path of the polarization element 12, and selectively converts the linearly polarized light into first polarized light or second polarized light; the scanning mirror 14 is disposed in the output optical path of the optical phase modulator 13, and scans the first polarized light or the second polarized light to convert the first polarized light or the second polarized light into a diverging spherical beam.

[0067] The laser emitter 11 emits a fine beam, which refers to a beam of light emitted from the same object point (or virtual image point) that reaches the pupil of the human eye, forming a beam with a cross-section of less than 2 mm and an angle difference of less than 5°. Because the light entering the eye is a fine beam, the human eye can clearly see the image over a large depth of field. When the human eye focuses and the binoculars converge to observe natural objects at different distances, the virtual image can be clearly displayed independently of the lens's focusing, thus resolving the convergence-accommodation conflict.

[0068] Optionally, the polarization element 12 can be a wire grid polarizer, a dichroic polarizer, or a birefringent polarizer, etc.

[0069] Meanwhile, the optical phase modulator 13 includes a first phase element 131 and an electrically controlled half-wave plate 132 arranged sequentially along the optical path transmission direction. The first phase element 131 can be a liquid crystal phase modulator used to convert linearly polarized light into first polarized light. The electrically controlled half-wave plate 132 has an on / off state to selectively convert the first polarized light into second polarized light or not convert the first polarized light. For example, in the off state, the electrically controlled half-wave plate 132 has no phase modulation function for the beam, and the first polarized light remains the first polarized light after passing through the electrically controlled half-wave plate 132. In the on state, the electrically controlled half-wave plate 132 has a phase modulation function for the beam, and the first polarized light is converted into second polarized light after passing through the electrically controlled half-wave plate 132.

[0070] Preferably, the scanning galvanometer 14 is a two-dimensional scanning galvanometer, which can be rotated controllably in two directions, typically the horizontal and vertical directions. The beam is reflected by the two-dimensional scanning galvanometer to form a diverging spherical beam.

[0071] A diverging spherical beam is incident on a first-order polarizer holographic element 30. In this embodiment, the first-order polarizer holographic element 30 is overlaid on the surface of the waveguide device 20 and faces the coupling region of the waveguide device 20. The first polarized light or the second polarized light diffracted by the first-order polarizer holographic element 30 is coupled into the waveguide device 20 through the coupling region, and the waveguide device 20 performs optical path folding on the beam. Optionally, the waveguide device 20 can be a grating waveguide, which is used to receive the imaging beam generated by the image generation unit 10 and perform optical path folding on the imaging beam.

[0072] In this embodiment, the second phase element 40 is embedded within the waveguide device 20. The second phase element 40 can be an electrically controlled phase element, used to receive the imaging beam after optical path folding and selectively convert the imaging beam into first polarized light or second polarized light. The electrically controlled phase element can be a liquid crystal phase modulator, which changes the alignment of liquid crystal molecules by applying voltage, thereby changing the polarization state of the beam. Alternatively, the electrically controlled phase element can also be a magneto-optical modulator, which uses changes in the magnetic field to change the polarization state of the beam.

[0073] The secondary polarizer holographic element 50 is disposed in the coupling region within the waveguide device 20. The secondary polarizer holographic element 50 is covered on the surface of the coupling region or embedded in the waveguide device 20. Specifically, the secondary polarizer holographic element 50 can be embedded into the waveguide device 20 by adhesive bonding or thin film embedding molding process. The third polarization diffraction element 51 and the fourth polarization diffraction element 52 can also be fixed together by adhesive bonding or other methods to form a composite structure.

[0074] Meanwhile, the near-eye display system also includes an eye-tracking device 60. The second phase element 40 has an on / off state to convert the imaging beam into first polarized light or second polarized light. The eye-tracking device 60 is signal-connected to the second phase element 40 and the electrically controlled half-wave plate 132. The eye-tracking device 60 can monitor the position of the human pupil in real time and adjust the working state of the second phase element 40 and the electrically controlled half-wave plate 132 according to the pupil position to ensure that the imaging beam can be converted into the required polarization state at the correct time, so that the image beam can be focused on the correct eye point.

[0075] The implementation principle of this embodiment is as follows: This system has 4 states, namely state 1 / 2 / 3 / 4.

[0076] In state 1, the electrically controlled half-wave plate 132 is off. The beam emitted from the scanning galvanometer 14 is first-polarized light and is incident on the first-order polarizer holographic element 30. The first polarization diffraction element 31 diffracts the first-polarized light, and its outgoing light is still first-polarized light. The second polarization diffraction element 32 has no effect on the first-polarized light. The second phase element 40 is off. After the first-polarized light exits through the second phase element 40, its polarization state remains unchanged, still being first-polarized light. The third polarization diffraction element 51 diffracts the incident first-polarized light into a converging spherical beam of first polarization, with its convergence point being the first eye point 70. The fourth polarization diffraction element 52 has no effect on the first-polarized light. If the pupil of the human eye is at the first eye point 70, the observer will see the image.

[0077] In state 2, the electrically controlled half-wave plate 132 is in the open state. The beam emitted from the scanning mirror 14 is second-polarized light and is incident on the first-order polarizer holographic element 30. The first polarization diffraction element 31 has no effect on the second-polarized light, while the second polarization diffraction element 32 diffracts the second-polarized light, and its outgoing light is still second-polarized light. Since the diffraction directions of the outgoing light from the first polarization diffraction element 31 and the second polarization diffraction element 32 are different for incident light in the same direction, the beam directions emitted from the polarization-selective diffraction element are different in state 2 and state 1. The second phase element 40 is in the open state, and the second-polarized light is converted into first-polarized light after exiting the second phase element 40. The third polarization diffraction element 51 diffracts the incident first-polarized light into a converging spherical beam of first polarization, with its convergence point being the second eye point 71. The fourth polarization diffraction element 52 has no effect on the first-polarized light. If the pupil of the human eye is at the second eye point 71, the observer will see an image.

[0078] In state 3, the electrically controlled half-wave plate 132 is in the off state. The beam emitted from the scanning galvanometer 14 is first polarized light and is incident on the first-order polarizer holographic element 30. The first polarization diffraction element 31 diffracts the first polarized light, and its outgoing light is still first polarized light. The second polarization diffraction element 32 has no effect on the first polarized light. The second phase element 40 is in the on state, and the first polarized light is converted into second polarized light after exiting through the second phase element 40. The third polarization diffraction element 51 has no effect on the second polarized light, and the fourth polarization diffraction element 52 diffracts the incident second polarized light into a converging spherical beam of second polarization. Its convergence point is the third eye point 72. If the pupil of the human eye is at the third eye point 72, the observer will see the image.

[0079] In state 4, the electrically controlled half-wave plate 132 is in the on state. The beam emitted from the scanning galvanometer 14 is second-polarized light and is incident on the first-order polarizer holographic element 30. The first polarization diffraction element 31 has no effect on the second-polarized light, while the second polarization diffraction element 32 diffracts the second-polarized light, and its outgoing light is still second-polarized light. The second phase element 40 is in the off state, and the polarization state of the second-polarized light remains unchanged after exiting through the second phase element 40. The third polarization diffraction element 51 has no effect on the second-polarized light, while the fourth polarization diffraction element 52 diffracts the incident second-polarized light into a converging spherical beam of second polarization, with its convergence point being the fourth eye point 73. If the pupil of the human eye is at the fourth eye point 73, the observer will see the image.

[0080] Furthermore, the eye-tracking device 60 tracks the position of the pupils in real time, determining the system's state (1 / 2 / 3 / 4) based on the pupil position to ensure the eye receives the image. The system can only be in one of these states, meaning only one of the following eye points—first eye point 70, second eye point 71, third eye point 72, or fourth eye point 73—has an image. This prevents two images from entering the eye simultaneously, thus avoiding image crosstalk. This method not only expands the eye-tracking range but also avoids image crosstalk and dark areas, significantly improving the user experience.

[0081] Example 2

[0082] This embodiment also discloses a near-eye display method based on retinal projection, including the following steps:

[0083] S10, Generate an imaging beam containing image information. This includes:

[0084] S11. The image generation unit 10 can selectively generate either first polarized light or second polarized light carrying image information. Specifically, the electronically controlled half-wave plate 132 can selectively generate either first polarized light or second polarized light.

[0085] S12. A primary polarizing holographic element 30 is provided. The primary polarizing holographic element 30 is used to receive first polarized light or second polarized light carrying image information. The primary polarizing holographic element 30 includes a first polarizing diffraction element 31 and a second polarizing diffraction element 32 stacked together. The first polarizing diffraction element 31 diffracts the first polarized light and transmits the second polarized light, and the second polarizing diffraction element 32 diffracts the second polarized light and transmits the first polarized light, thereby folding the optical path of the diffracted first polarized light or second polarized light.

[0086] S20. Receive the imaging beam and fold the imaging beam in the optical path.

[0087] Specifically, the imaging beam can be received and transmitted through the waveguide device 20.

[0088] S30. Receive the imaging beam after optical path folding, and selectively convert the imaging beam into a first polarized light or a second polarized light, wherein the polarization states of the first polarized light and the second polarized light are orthogonal.

[0089] Specifically, the second phase element 40 is used to receive the imaging beam after it has been folded in the optical path. The second phase element 40 can be an electrically controlled phase element.

[0090] S40. Provide a secondary polarization holographic element 50, the secondary polarization holographic element 50 including a third polarization diffraction element 51 and a fourth polarization diffraction element 52 stacked together, the third polarization diffraction element 51 diffracts first polarized light and transmits second polarized light, the fourth polarization diffraction element 52 diffracts second polarized light and transmits first polarized light, so as to converge the first polarized light or the second polarized light to different viewpoints.

[0091] S50. Provide an eye-tracking device 60, which tracks the position of the pupil in real time and converts the imaging beam into first polarized light or second polarized light according to the position of the pupil.

[0092] Specifically, the eye-tracking device 60 controls the state of the image generation unit 10 and the second phase element 40 to select the first polarized light or the second polarized light for transmission and diffraction according to the position of the pupil, so that the first polarized light or the second polarized light can converge to different viewpoints, avoiding the problem of image crosstalk caused by two images entering the human eye at the same time.

[0093] This application enables the imaging beam to be selectively diffracted or transmitted through different polarization diffraction elements, thereby forming different eye points in real time and thus expanding the eyebox of the system.

[0094] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A near-eye display system based on retinal projection, characterized in that, include: An image generation unit (10) is used to generate an imaging beam with image information; Waveguide device (20) is used to receive the imaging beam of the image generation unit (10) and fold the imaging beam in the optical path; The second phase element (40) is used to receive the imaging beam after optical path folding and selectively convert the imaging beam into first polarized light or second polarized light, wherein the polarization states of the first polarized light and the second polarized light are orthogonal. A secondary polarizer holographic element (50) is used to receive the first polarized light or the second polarized light emitted from the second phase element (40). The secondary polarizer holographic element (50) includes a third polarization diffraction element (51) and a fourth polarization diffraction element (52) stacked together. The third polarization diffraction element (51) diffracts the first polarized light and transmits the second polarized light, and the fourth polarization diffraction element (52) diffracts the second polarized light and transmits the first polarized light. The second phase element (40) selectively transforms the first polarized light or the second polarized light to converge the first polarized light or the second polarized light to different viewpoints through the secondary polarizer holographic element (50); The image generation unit (10) for generating an imaging beam with image information includes: The image generation unit (10) is used to selectively generate first polarized light or second polarized light with image information, and the first polarized light or second polarized light is incident on the waveguide device (20); The near-eye display system also includes: A primary polarizing holographic element (30) is used to receive first polarized light or second polarized light generated by the image generation unit (10). The primary polarizing holographic element (30) includes a first polarizing diffraction element (31) and a second polarizing diffraction element (32) stacked together. The first polarizing diffraction element (31) diffracts the first polarized light and transmits the second polarized light, and the second polarizing diffraction element (32) diffracts the second polarized light and transmits the first polarized light. The first polarized light or the second polarized light diffracted by the first-level polarizing holographic element (30) is incident into the waveguide device (20).

2. The near-eye display system based on retinal projection according to claim 1, characterized in that, The image generation unit (10) includes: A laser emitter (11) is used to emit a line beam composed of red, green, and blue modulated beams; A polarization element (12) is disposed in the light output path of the laser emitter (11) to convert the line beam emitted by the laser emitter (11) into linearly polarized light. An optical phase modulator (13) is disposed in the light output path of the polarization element (12), and the optical phase modulator (13) selectively converts the linearly polarized light into first polarized light or second polarized light; and A scanning galvanometer (14) is disposed on the light output path of the optical phase modulator (13). The scanning galvanometer (14) is used to scan the first polarized light or the second polarized light to convert the first polarized light or the second polarized light into a diverging spherical beam.

3. The near-eye display system based on retinal projection according to claim 2, characterized in that: The optical phase modulator (13) includes a first phase element (131) and an electrically controlled half-wave plate (132) arranged sequentially along the optical path transmission direction. The first phase element (131) is used to convert linearly polarized light into first polarized light. The electrically controlled half-wave plate (132) has an on / off state to convert the first polarized light into second polarized light or not to convert the first polarized light, or... The first phase element (131) is used to convert linearly polarized light into second polarized light, and the electrically controlled half-wave plate (132) has an on / off state to convert the second polarized light into first polarized light or not to convert the second polarized light.

4. The near-eye display system based on retinal projection according to claim 3, characterized in that, The near-eye display system further includes an eye-tracking device (60), the second phase element (40) having an on / off state to convert the imaging beam into a first polarized light or a second polarized light, and the eye-tracking device (60) being signal-connected to the second phase element (40) and the electronically controlled half-wave plate (132).

5. The near-eye display system based on retinal projection according to claim 1, characterized in that, The near-eye display system further includes an eye-tracking device (60), the second phase element (40) having an on / off state to convert the imaging beam into a first polarized light or a second polarized light, and the eye-tracking device (60) being signal-connected to the second phase element (40).

6. The near-eye display system based on retinal projection according to claim 1, characterized in that: The secondary polarizer holographic element (50) is covered on the surface of the waveguide device (20) or embedded in the waveguide device (20).

7. A near-eye display method based on retinal projection, characterized in that, Includes the following steps: Generate an imaging beam containing image information; Receive the imaging beam and fold the imaging beam in the optical path; It receives the imaging beam after optical path folding and selectively converts the imaging beam into first polarized light or second polarized light, wherein the polarization states of the first polarized light and the second polarized light are orthogonal. A secondary polarization holographic element (50) is provided, the secondary polarization holographic element (50) includes a third polarization diffraction element (51) and a fourth polarization diffraction element (52) stacked together. The third polarization diffraction element (51) diffracts first polarized light and transmits second polarized light, and the fourth polarization diffraction element (52) diffracts second polarized light and transmits first polarized light, so as to converge the first polarized light or the second polarized light to different viewpoints; The step of generating an imaging beam with image information includes: Selectively generate either first-polarized light or second-polarized light carrying image information; Before the step of receiving the imaging beam and performing optical path folding on the imaging beam, the method further includes: A primary polarizing holographic element (30) is provided. The primary polarizing holographic element (30) is used to receive first polarized light or second polarized light with image information. The primary polarizing holographic element (30) includes a first polarizing diffraction element (31) and a second polarizing diffraction element (32) stacked together. The first polarizing light is diffracted by the first polarizing diffraction element (31) and the second polarized light is transmitted. The second polarizing light is diffracted by the second polarizing diffraction element (32) and the first polarized light is transmitted. The optical path of the first polarized light or the second polarized light after diffraction is folded.

8. The near-eye display method based on retinal projection according to claim 7, characterized in that, It also includes the following steps: An eye-tracking device (60) is provided, which tracks the position of the pupil in real time and converts the imaging beam into first polarized light or second polarized light according to the position of the pupil.

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