Freeform surface waveguide system and near-eye display device

Abstract

The application discloses a free-form surface waveguide system and a near-eye display device, which comprise a main mirror and a compensation mirror; a quarter-wave plate is attached to a first surface of the main mirror, and a polarization splitting film is arranged on a coupling-out splitting surface; the compensation mirror is bonded to the main mirror; first polarized light entering the main mirror through an incident surface is propagated in the direction of a second surface and a fourth surface after multiple reflections in the main mirror; wherein part of the first polarized light is reflected to the first surface after total reflection at the second surface, and part of the first polarized light is transmitted to the compensation mirror through the coupling-out splitting surface and is reflected to the first surface after total reflection at the fourth surface; then, the first polarized light reflected to the first surface is transmitted through the first surface and is totally reflected at the surface of the quarter-wave plate close to the human eye, the first polarized light becomes second polarized light after passing through the quarter-wave plate twice, and the second polarized light is reflected by the coupling-out splitting surface and is emitted from the first surface, so that the first polarized light entering the compensation mirror can participate in human eye imaging, and the field of view is expanded.

Description

Technical Field

[0001] This invention relates to a freeform waveguide system and also to a near-eye display device. Background Technology

[0002] Augmented reality (AR) technology has the ability to perfectly blend real and virtual scenes, and has become a hot topic of research and discussion in recent years. Its application scope is also constantly expanding, gradually penetrating into various fields such as consumer goods, medicine, and industry.

[0003] Optical see-through near-eye display technology is a core presentation method for augmented reality. In existing near-eye display optical solutions, to achieve both compact structure and see-through display, light typically needs to propagate within the optical element via total internal reflection and then merge with the see-through light path near the eye. Typical applications include freeform prism solutions and waveguide display solutions. These solutions usually include a primary mirror at a near-eye location to achieve the see-through display.

[0004] Freeform waveguide technology is a near-eye display technology that integrates freeform surface technology and waveguide technology. It allows light to propagate within the waveguide via total internal reflection, and then be reflected at the beam-splitting surface along the visual axis to form an image in the human eye. A typical application is the EPSON MOVERIOBT series of smart glasses. However, freeform waveguide technology, due to the limitation of the beam-splitting surface size, cannot achieve a large field of view, typically less than 35°. Furthermore, in freeform waveguide systems, the compensation lens used for perspective does not participate in the virtual image formation. When a larger field of view is required, the thickness of the beam-splitting surface used to form the virtual image is often significant, creating a clear conflict between expanding the field of view and achieving a thinner and lighter product. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a freeform waveguide system that combines freeform surface, waveguide and polarization to enable the image light entering the compensation mirror to participate in imaging, thereby allowing the light entering the human eye to break through the limitation of the beam splitter and obtain a larger field of view.

[0006] Another technical problem to be solved by the present invention is to provide an augmented reality near-eye display device.

[0007] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0008] A freeform waveguide system, comprising:

[0009] The primary mirror includes an incident surface, a first reflecting surface, a second reflecting surface, a first surface, a second surface, and a coupling beam-splitting surface; the first surface faces the human eye, and the second surface faces away from the human eye; the coupling beam-splitting surface is provided with a polarizing beam-splitting film, and a quarter-wave plate is attached to the first surface;

[0010] A compensating lens is disposed on one side of the main mirror and bonded to the coupling beam splitter of the main mirror; the compensating lens includes a third surface and a fourth surface, the third surface and the first surface together form the lens surface facing the human eye, and the fourth surface and the second surface together form the lens surface away from the human eye.

[0011] The incident surface is used to receive the first polarized light. The first polarized light that enters the main mirror through the incident surface undergoes multiple reflections within the main mirror and then propagates toward the second and fourth surfaces. Among them, part of the first polarized light undergoes total internal reflection on the second surface and then propagates toward the first surface; part of the first polarized light passes through the coupling beam splitter and enters the compensation mirror, undergoes total internal reflection on the fourth surface, passes through the coupling beam splitter and then propagates toward the first surface.

[0012] The first polarized light incident on the first surface passes through the first surface and undergoes total internal reflection on the quarter-wave plate near the human eye side surface. The first polarized light passes through the quarter-wave plate twice and becomes second polarized light. Then, the second polarized light is reflected by the coupled beam splitter and exits from the first surface to form an image in the human eye.

[0013] Preferably, the multiple reflections occurring within the primary mirror include sequential reflections on the first reflecting surface and total internal reflections on the second reflecting surface.

[0014] Preferably, the first reflective surface is concave to the incident surface, and the first reflective surface is covered with a reflective film.

[0015] Preferably, the first polarized light forms an intermediate image as it propagates towards the second surface and the fourth surface after being reflected by the second reflecting surface.

[0016] Preferably, the first surface is a plane.

[0017] Preferably, the incident surface and the second reflecting surface have the same shape and partially overlap.

[0018] Preferably, before the first polarized light is reflected by the coupled beam-splitting surface, the incident angles at the second reflecting surface, the second surface, and the quarter-wave plate all satisfy the condition of total internal reflection.

[0019] Preferably, the distance between the first surface and the second surface is less than the distance between the second reflective surface and the second surface; and the thickness between the first surface and the second surface is less than 10 mm.

[0020] Preferably, the surface shapes of the first reflecting surface and the coupled beam-splitting surface are freeform surfaces.

[0021] A near-eye display system includes the aforementioned freeform waveguide system, and further includes an image source and a relay optical system. The image source provides first polarized light to the relay optical system, and the first polarized light enters the primary mirror from the incident surface after being refracted by the relay optical system.

[0022] Preferably, the relay optical system is an off-axis optical system.

[0023] The freeform waveguide system provided by this invention includes a primary mirror and a compensating mirror. By setting a quarter-wave plate on the surface of the primary mirror facing the human eye and attaching a polarizing beam splitter film to the coupling beam splitter surface of the primary mirror, the virtual image light entering the compensating mirror can participate in human eye imaging without being limited by the coupling beam splitter surface. This achieves a large field of view while reducing the thickness of the lens in the visual axis direction, and at the same time improves the utilization rate of virtual image light. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall optical path of the near-eye display device provided in an embodiment of the present invention;

[0025] Figure 2 This is the MTF measurement value of the freeform waveguide system shown in the embodiment when the exit pupil is 4mm;

[0026] Figure 3 This is a distortion diagram of the freeform waveguide system shown in the embodiment;

[0027] Figure 4 This is a schematic diagram showing the distribution of the first polarized light entering the compensating lens in the human eye's field of vision;

[0028] Figure 5 This is a schematic diagram of the overall optical path of a near-eye display device provided in another embodiment of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. In the following description, the direction where the human eye is located is taken as the origin, the visual axis direction is taken as the Z-axis, the direction perpendicular to the Z-axis is taken as the Y-axis, and the direction perpendicular to the ZY plane is taken as the X-axis. Figure 1 The figure shows the ZY cross section of the near-eye display device.

[0030] like Figure 1 As shown, the near-eye display device provided in this embodiment of the invention includes an image source ( Figure 1The image plane position OI, lens group 40, and freeform waveguide are shown. The freeform waveguide includes a primary mirror 20 and a compensating mirror 30, which are cemented together to form a lens in front of the human eye. To fully utilize the different components, the freeform waveguide provided by this invention incorporates polarizing optical elements, introducing polarization technology into the freeform waveguide. This allows the compensating mirror 30, used for perspective, to also participate in the formation of virtual images, enabling the image light entering the compensating mirror 30 to participate in human eye imaging. This provides greater freedom in optical design, allowing for the design of products with a larger field of view and a thinner overall structure. For example, a freeform waveguide with a thickness of less than 10 mm can achieve a field of view of not less than 35°.

[0031] Specifically, the image source provides first polarized light to the relay optical system 40. The first polarized light emitted by the image source is refracted by the relay optical system 40 and then enters the primary mirror 20 of the freeform waveguide. The image source can be a display device such as LCD, OLED, or LCOS. Preferably, an LCOS or OLED display device that allows for significant brightness adjustment is selected as the image source. Alternatively, a screen reflecting linearly polarized light can be selected as the image source, or a polarizer can be added in front of the screen.

[0032] A relay optical system is used to guide the first polarized light emitted from an image source to the incident surface of a freeform waveguide after refraction. A relay optical system can be, for example,... Figure 1 The off-axis optical lens group shown can also be implemented in other ways, and no restrictions are placed here. For example... Figure 1 The relay optical system 40 shown includes lenses 41 and 42, which are positioned off-axis to better correct aberrations. The surface profiles of lenses 41 and 42 can be spherical, aspherical, or freeform. Preferably, lenses with freeform or aspherical surface profiles are selected to correct advanced aberrations.

[0033] like Figure 1As shown, the freeform waveguide includes a primary mirror 20 and a compensating mirror 30. The primary mirror 20 includes an incident surface arranged from the image source towards the human eye (EY), a first reflecting surface S25, a second reflecting surface S24, a second surface S23, a coupling beam-splitting surface S22, and a first surface S21; the first surface S21 faces the human eye, and the second surface S23 is away from the human eye; the coupling beam-splitting surface S22 is provided with a polarizing beam-splitting film, and a quarter-wave plate 10 is attached to the first surface S21. The compensating mirror 30 includes an incident surface S33, a third surface S32, and a fourth surface S31. The incident surface S33 of the compensating mirror 30 and the coupling beam-splitting surface S22 of the primary mirror 20 are cemented together; the third surface S32 and the first surface S21 form the surface of the lens facing the human eye; the fourth surface S31 and the second surface S23 form the surface of the lens away from the human eye. Preferably, the first surface S21 and the third surface S32 use the same surface shape, and the second surface S23 and the fourth surface S31 use the same surface shape. While ensuring total internal reflection of the primary mirror 20 and the compensating mirror 30, the surface shapes of the lenses facing the human eye and those away from the human eye are either identical or differ to suit human visual acuity.

[0034] The incident surface receives the first polarized light. The first polarized light entering the primary mirror 20 through the incident surface undergoes multiple reflections within the primary mirror 20 before propagating towards the second surface S23 and the fourth surface S31. Part of the first polarized light undergoes total internal reflection at the second surface S23 and then propagates towards the first surface S21. Another part of the first polarized light passes through the coupling beam-splitting surface S22 into the compensating mirror 30, undergoes total internal reflection at the fourth surface S31, passes through the coupling beam-splitting surface S22 again, and propagates towards the first surface S21. Since the refractive indices of the primary mirror 20 and the quarter-wave plate 10 are similar, the first polarized light propagating towards the first surface S21 passes through the first surface S21 into the quarter-wave plate 10, undergoes total internal reflection at the surface of the quarter-wave plate 10 near the human eye, and becomes second polarized light after passing through the quarter-wave plate 10 twice. Then, the second polarized light is reflected by the coupling beam-splitting surface S22, passes through the first surface S21 and the quarter-wave plate 10, and exits to form an image in the human eye. The light rays reaching the human eye are circularly polarized.

[0035] The incident surface of the primary mirror 20 and the second reflecting surface S24 can be partially overlapping surfaces with identical surface shapes. For example... Figure 1 As shown, the incident surface is the part of the second reflecting surface S24 near the edge; the incident surface and the second reflecting surface S24 can be partially overlapping or completely non-overlapping surfaces; the second reflecting surface S24 is an approximately planar curved surface, and its surface shape can be spherical, aspherical, or freeform.

[0036] The first reflecting surface S25 is located away from the human eye and is concave to the incident surface. The surface shape of the first reflecting surface S25 can be spherical, aspherical, or freeform, preferably freeform. The first reflecting surface S25 is covered with a reflective film, which can be a total internal reflection film. The light rays reflected by the first reflecting surface S25 satisfy the total internal reflection condition at the incident angle of the second reflecting surface S24. Before being reflected by the coupled beam-splitting surface S22, the light rays reflected by the second reflecting surface S24 satisfy the total internal reflection condition at the incident angles of the second surface S23, the fourth surface S31, and the quarter-wave plate 10.

[0037] The first surface S21 faces the human eye, and the second surface S23 faces away from the human eye. The first surface S21 and the second surface S23 are the front and rear surfaces of the lens, and both have the same surface shape with no difference in power. Alternatively, the first surface S21 and the second surface S23 have a certain optical power to match the human eye's vision. The first surface S21 is preferably flat to facilitate the attachment of the quarter-wave plate 10. Under the condition that the film-coating process meets the requirements, the first surface S21 can also be curved, such as using an aspherical or freeform surface.

[0038] The surface design of the first surface S21 and the second surface S23 should ensure total internal reflection of light within the primary mirror 20 and the quarter-wave plate 10. The distance between the first surface S21 and the second surface S23 is less than the distance between the second reflecting surface S24 and the second surface S23. Specifically, the distance between the second reflecting surface S24 and the second surface S23 near the position of the first surface S21 is defined as the distance between the second reflecting surface S24 and the second surface S23. In other words, the thickness of the portion of the primary mirror 20 that transmits ambient light in front of the eye is less than the thickness of the portion located near the side of the face. The lens has a smaller thickness in the portion corresponding to the eye, with the thickness between the first surface S21 and the second surface S23 being less than 10 mm.

[0039] The beam-splitting surface S22 is located in front of the eye along the visual axis and intersects the visual axis at an angle. The two ends of the beam-splitting surface S22 are connected to the first surface S21 and the second surface S23, respectively. The surface shape of the beam-splitting surface S22 is preferably a free-form surface.

[0040] A compensating lens 30 is disposed on one side of the primary lens 20 and cemented to the output beam-splitting surface S22 of the primary lens 20. The compensating lens 30 includes an incident light surface S33, a third surface S32, and a fourth surface S31. The incident light surface S33 and the output beam-splitting surface S22 have the same surface shape and are cemented together. The third surface S32 has the same surface shape as the first surface S21 and forms the inner surface of the lens. The fourth surface S31 has the same surface shape as the second surface S22 and forms the outer surface of the lens.

[0041] In this embodiment, the beam splitting surface S22 is provided with a polarizing beam splitting film, and a quarter-wave plate 10 is attached to the first surface S21, so that the first polarized light entering the compensation mirror 30 through the beam splitting surface S22 can also participate in human eye imaging by total internal reflection and re-entering the primary mirror.

[0042] To facilitate the description of the optical principle of the freeform waveguide provided in this application, Figure 1 In this section, two representative rays, R1 and R2, emanating from the image plane OI, representing the edge of the field of view, are used for illustration. Ray R1 is the inner ray closer to the human eye, and ray R2 is the outer ray farther from the human eye. Both rays R1 and R2 are first-polarized light. The following description uses p-type polarized light as an example to illustrate the optical principle of the entire near-eye display system. It can be understood that using s-type polarized light as the image source can achieve the same imaging effect.

[0043] P-type polarized light R1 and R2, after being refracted by lens 40, are coupled into primary mirror 20 from surface S24. After passing through the first reflecting surface S25, which is coated with a total internal reflection film, the light undergoes total internal reflection on this surface and reaches surface S24 again. At this point, the incident angle of the incident light on surface S24 satisfies the condition for total internal reflection, resulting in total internal reflection. When the second reflecting surface and the incident surface do not coincide, a total internal reflection film can be applied to the surface of the second reflecting surface. In this case, the incident angle of the light reaching this surface may not satisfy the restriction of the total internal reflection angle condition. This application does not limit the type of total internal reflection of light on the second reflecting surface.

[0044] In this embodiment, when P-type polarized light propagates from the second reflecting surface S24 to the second surface S23, the propagation paths of beams R1 and R2 in the optical path are different, which will be described below.

[0045] R1 beam emitted from the image source, close to the human eye ( Figure 1The solid line beam (R1) is reflected by the second reflecting surface S24 and then strikes the second surface S23. The angle of incidence on this surface satisfies the condition for total internal reflection, resulting in all rays undergoing total internal reflection and striking the first surface S21. Because the refractive index difference between the quarter-wave plate 10 and the primary mirror 20 is small, the R1 ray, after reaching the first surface S21, enters the quarter-wave plate 10 bonded to it. Total internal reflection occurs at the surface S11 of the quarter-wave plate 10 closest to the human eye, returning to the first surface S21 and striking the coupling beam-splitting surface S22. During this process, the R1 beam passes through the quarter-wave plate 10 twice, changing its polarization state from P-type to S-type polarization. The polarized R1 ray reaches the coupling beam-splitting surface S22, which is coated with a PBS beam-splitting film. This film transmits P-type polarized light and reflects S-type polarized light, so the R1 ray is reflected and finally exits from the surface S11 of the quarter-wave plate 10, entering the human eye to form an image. At this point, because the S-polarized light has passed through a quarter-wave plate, the human eye ultimately sees the R1 ray with circular polarization.

[0046] The R2 beam emitted from the image source, away from the human eye ( Figure 1 The dashed beam (as shown in the image) is reflected by the second reflecting surface S24 and then directed towards the coupling beam splitter S22 and the fourth surface S31. The coupling beam splitter S22 is coated with a polarizing film that transmits P-type polarized light and reflects S-type polarized light. The R2 beam passes through the coupling beam splitter S22 and enters the compensating mirror 30. The fourth surface S31 of the compensating mirror 30 and the second surface S23 of the freeform prism are the same surface. The R2 beam undergoes total internal reflection on the fourth surface S31, passes through the coupling beam splitter S22 again, enters the primary mirror 20, reaches the first surface S21, and then enters the quarter-wave plate 10. The R2 ray undergoes total internal reflection on the surface S11 of the quarter-wave plate 10 near the human eye. The R2 ray passes through the quarter-wave plate 10 twice, and the P-type polarized light becomes S-type polarized light. The S-type polarized light R2 ray is reflected at the coupling beam splitter S22 and exits through the first surface S21 and the quarter-wave plate 10. Ultimately, the human eye sees the R2 beam as having a circularly polarized state.

[0047] Rays R1 and R2 form an intermediate image within the primary mirror 20. Figure 1 In the embodiment shown, all light rays form an intermediate image as they propagate from the second reflecting surface S24 toward the second surface S23 and the fourth surface S31.

[0048] The above example illustrates the propagation path of the first polarized light provided by the image source in the primary mirror 20 and the compensation mirror 30, using two edge-positioned light rays R1 and R2 as examples. For the light ray located between R1 and R2, after being reflected by the second reflecting surface S24, during its propagation towards the second surface S23 and the fourth surface S31, part of the first polarized light is directed towards the second surface S23, undergoes total internal reflection at the second surface S23, and then propagates towards the first surface S21; another part of the first polarized light passes through the coupling beam-splitting surface S22 into the compensation mirror 30, undergoes total internal reflection at the fourth surface S31, passes through the coupling beam-splitting surface S22, and then propagates towards the first surface S21. It can be understood that the light emitted from the image source is continuously distributed, rather than... Figure 1 The specific portion of the separated light beams shown, which rays strike the second surface S23 and which rays pass through the coupling beam-splitting surface S22 and strike the fourth surface S31, depends on the direction of light propagation. Since all the first polarized light entering the primary mirror 20 undergoes total internal reflection by the first reflecting surface S25 and the second reflecting surface S24, and the first polarized light, after passing through the first surface S21, undergoes total internal reflection at the quarter-wave plate 10 near the eye, and its subsequent propagation path is the same for all rays, it will not be described further here.

[0049] Tables 1 and 2 show the surface shape parameters of each surface in the first embodiment of this application. To reduce the difficulty of design and manufacturing, the surface S11 of the quarter-wave plate 10, the first surface S21 and the second surface S23 of the primary mirror, and the third surface S32 and the fourth surface S31 of the compensating mirror 30 are all represented by a unified surface shape expression, and are preferably planar. The surface shape of the second reflecting surface S24 can be spherical, aspherical, or freeform; the coupling surface S22 and the first reflecting surface S25 are surfaces represented by a unified surface shape expression, and are preferably freeform.

[0050] The primary mirror 20 and the compensation surface 30 have surfaces S22 and S33 with the same surface shape. After the two surfaces are glued together, the optical power of the glued prism is close to 0, and the perspective distortion is less than 2%. It does not affect the human eye's view of the external environment.

[0051] Table 1. Surface shape parameters of each surface in the freeform waveguide system.

[0052] EY spherical unlimited refraction S21 / S32 spherical unlimited 1.651 21.5 refraction S22 XY polynomial 1256.59 1.651 21.5 reflection S23 / S31 spherical unlimited 1.651 21.5 reflection S24 spherical -300.14 1.651 21.5 reflection S25 XY polynomial -86.42 1.651 21.5 reflection 411 aspherical -9.44 1.573 67.8 refraction 412 spherical -26.49 refraction 421 aspherical -6.09 1.593 67.3 refraction 422 aspherical -43.46 refraction

[0053] Table 2. Eccentricity data for each surface in the freeform waveguide system.

[0054]

[0055]

[0056] The near-eye display device provided in the above embodiments can achieve an optical scheme with a field of view of 37°, an exit pupil distance of 18mm, an exit pupil diameter of 8mm, and a lens thickness of 9.3mm at the exit pupil, which is less than 10mm.

[0057] The MTF and distortion of the near-eye display device, such as Figure 2 As shown, when the exit pupil diameter is 4mm, the transfer function values ​​for all fields of view are greater than 0.4 at 30 line pairs / mm, fully meeting the needs of the human eye. The distortion of this near-eye display device is as follows: Figure 3 As shown, the system distortion rate is approximately 13%. System distortion can be pre-corrected during image display using electronic correction methods, without affecting the final viewing effect.

[0058] The horizontal field of view distribution of this near-eye display device is as follows: Figure 4 As shown, the field of view θ formed by the light rays after the first polarized light is reflected by the second mirror S24 and then reflected by the second surface S23 to the first surface S21 at the exit pupil position satisfies the following relationship between the light rays after entering the compensation mirror 30 and being reflected by the fourth surface S31 to the first surface S21 at the exit pupil position: α≥θ / 4. In other words, by setting polarizing optical elements, the light rays entering the compensation mirror can participate in the human eye imaging, thereby increasing the exit pupil field of view by at least 1 / 4.

[0059] like Figure 5 As shown, the present invention also provides another embodiment where the first surface S21 is a curved surface (spherical, aspherical, or freeform). Tables 3 and 4 provide surface shape parameters for different optical surfaces in a specific embodiment, wherein the first surface S21, the second surface S23, the third surface S31, and the fourth surface S32 are all spherical. When the first surface S21, the second surface S23, the third surface S31, and the fourth surface S32 are aspherical or freeform, the image quality of the virtual image can be improved.

[0060] Table 3. Surface shape parameters of each surface in the freeform waveguide system.

[0061]

[0062]

[0063] Table 4. Eccentricity data for each surface in the freeform waveguide system.

[0064]

[0065] Figure 4 The imaging principles of different light rays in the embodiments shown are as follows: Figure 1 Similarly, details will not be elaborated here. The near-eye display device provided in this embodiment can also achieve a diagonal field of view of more than 35°.

[0066] In summary, the freeform waveguide system provided by this invention, by placing a quarter-wave plate on the surface of the primary mirror near the human eye and polarizing elements such as a polarizing beam splitter on the coupling beam splitter surface, allows the first polarized light entering the compensation mirror to simultaneously participate in the human eye's imaging process. This increases the design freedom and has the potential to achieve higher performance requirements. Therefore, the field of view can be expanded without increasing the lens thickness, making it applicable to a wider range of scenarios.

[0067] The aforementioned freeform waveguide system uses side projection, which expands the human eye's field of vision in the vertical direction. Furthermore, the image source and relay optical system can be embedded in the temple support, making the overall design more similar to the shape of eyeglasses.

[0068] The freeform waveguide system and near-eye display device provided by this invention have been described in detail above. Any obvious modifications made by those skilled in the art without departing from the essence of this invention will constitute an infringement of the patent rights of this invention and will incur corresponding legal liability.

Claims

1. A freeform waveguide system, characterized in that... include: The primary mirror includes an incident surface, a first reflecting surface, a second reflecting surface, a first surface, a second surface, and a beam-splitting surface. The first surface faces the human eye, and the second surface is away from the human eye; The beam splitting surface is provided with a polarizing beam splitting film, and a quarter-wave plate is attached to the first surface; A compensating lens is disposed on one side of the main mirror and bonded to the coupling beam splitter of the main mirror; the compensating lens includes a third surface and a fourth surface, the third surface and the first surface together form the lens surface facing the human eye, and the fourth surface and the second surface together form the lens surface away from the human eye. The incident surface is used to receive the first polarized light. The first polarized light that enters the main mirror through the incident surface is reflected multiple times in the main mirror and then propagates in the direction of the second and fourth surfaces. In this process, a portion of the first polarized light undergoes total internal reflection on the second surface and then strikes the first surface; another portion of the first polarized light passes through the coupling beam splitter and enters the compensation mirror, undergoes total internal reflection on the fourth surface, passes through the coupling beam splitter, and then strikes the first surface. The two portions of first polarized light incident on the first surface pass through the first surface and undergo total internal reflection on the quarter-wave plate near the human eye. The first polarized light becomes second polarized light after passing through the quarter-wave plate twice. Then, the second polarized light is reflected by the coupled beam splitter and exits from the first surface to image the human eye. The field of view θ formed by the light rays reflected from the second surface to the first surface at the exit pupil position and the field of view α formed by the light rays reflected from the fourth surface to the first surface after entering the compensating mirror at the exit pupil position satisfy the following relationship: α≥θ / 4.

2. The freeform waveguide system as described in claim 1, characterized in that: The multiple reflections occurring within the primary mirror include reflections at the first reflecting surface and total internal reflections at the second reflecting surface.

3. The freeform waveguide system as described in claim 2, characterized in that: The first polarized light forms an intermediate image as it propagates towards the second and fourth surfaces after being reflected by the second reflecting surface.

4. The freeform waveguide system as described in claim 2, characterized in that: The first surface is a plane, an aspherical surface, or a freeform surface.

5. The freeform waveguide system as described in claim 1, characterized in that: The first reflective surface is concave to the incident surface, and the first reflective surface is covered with a reflective film.

6. The freeform waveguide system as described in claim 1, characterized in that: The surface shapes of the first reflecting surface and the coupled beam-splitting surface are freeform surfaces.

7. The freeform waveguide system as described in claim 1, characterized in that: The incident surface and the second reflecting surface have the same shape and partially overlap.

8. The freeform waveguide system as described in claim 1, characterized in that: Before being reflected by the coupled beam-splitting surface, the first polarized light satisfies the total internal reflection condition at the incident angles of the second reflecting surface, the second surface, and the quarter-wave plate.

9. The freeform waveguide system as described in claim 1, characterized in that: The thickness between the first surface and the second surface is less than 10 mm.

10. A near-eye display system, characterized in that: The system includes a freeform waveguide system as described in any one of claims 1-9, and further includes an image source and a relay optical system, wherein the image source provides first polarized light to the relay optical system, and the first polarized light enters the primary mirror from the incident surface after being refracted by the relay optical system.

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