AR optical modules and head-mounted display devices

Abstract

This application discloses an AR optical module and a head-mounted display device. The AR optical module includes a first lens and a second lens disposed along a first optical axis. The first lens includes a first surface, a second surface, and a third surface. The AR optical module also includes a liquid lens and a display screen disposed along a second optical axis. The liquid lens and the display screen are located on one side of the first surface. The display screen is configured to move relative to the liquid lens along the second optical axis. The liquid lens and the display screen are used to adjust the focal length of the AR optical module according to the user's viewing angle. The second lens is located on one side of the second surface, and a polarizing reflector is disposed between the second lens and the first lens.

Description

Technical Field

[0001] This application belongs to the field of optical display technology, specifically, it relates to an AR optical module and a head-mounted display device. Background Technology

[0002] In the current AR (Augmented Reality) technology field, traditional AR optical modules generally face a significant technical limitation: the lack of a flexible refractive adjustment mechanism. This deficiency directly leads to nearsighted or farsighted users having to wear glasses to correct their vision when using AR devices, which undoubtedly increases the burden on users. More importantly, this multi-layered visual correction method may introduce additional optical errors, such as increased aberrations, limited field of view, and image distortion, thereby adversely affecting the overall display effect of AR devices and the user's visual comfort. Summary of the Invention

[0003] The purpose of this application is to provide a new technical solution for an AR optical module and a head-mounted display device.

[0004] According to a first aspect of this application, an embodiment of this application provides an AR optical module, the AR optical module including a first lens and a second lens disposed along a first optical axis, wherein the first lens includes a first surface, a second surface and a third surface;

[0005] The AR optical module further includes a liquid lens and a display screen disposed along a second optical axis, and the liquid lens and the display screen are located on one side of the first surface. The display screen is configured to be movable relative to the liquid lens along the second optical axis. The liquid lens and the display screen are used to adjust the focal length of the AR optical module according to the user's viewing angle.

[0006] The second lens is located on one side of the second surface, and a polarizing reflector is disposed between the second lens and the first lens.

[0007] Optionally, the AR optical module further includes a polarizer disposed on the light-emitting surface of the display screen to convert the light emitted by the display screen into linearly polarized light.

[0008] Optionally, the incident light is folded twice within the first lens, thus passing through the first lens three times. The focal length of the light passing through the first lens three times is L1, and the focal length of the AR optical module is L, where 0.8 ≤ L1 / L ≤ 1.2.

[0009] Optionally, the first surface, the second surface, and the third surface are freeform surfaces.

[0010] Optionally, the second surface is the surface of the first lens away from the aperture stop, the second surface is bent toward the aperture stop, and the radius of curvature of the second surface is -200mm to -50mm.

[0011] Optionally, the polarizing reflector is disposed on the second surface;

[0012] The third surface is the surface of the first lens near the aperture stop, and the third surface is a total reflection surface.

[0013] Optionally, the focal length of the liquid lens is L3, 40mm≤L3≤80mm, and the moving distance of the display screen along the second optical axis is A, 0mm≤|A|≤3mm.

[0014] Optionally, the first lens and the second lens are cemented together to form a cemented lens assembly, wherein the transmitted light power of the cemented lens is 0.

[0015] Optionally, the surface of the second lens facing away from the first lens has the same surface shape as the third surface, wherein the third surface is the surface of the first lens near the aperture.

[0016] Optionally, the transmission axis of the polarizer is perpendicular to the transmission axis of the polarizing reflector.

[0017] According to a second aspect of this application, embodiments of this application provide a head-mounted display device, the head-mounted display device comprising:

[0018] The outer casing; and

[0019] The AR optical module as described in the first aspect.

[0020] One beneficial effect of the embodiments of this application is that:

[0021] This application provides a novel AR optical module design, characterized by its simple structure, high imaging clarity, and adjustable diopter. Specifically, the AR optical module of this application, through the design of a liquid lens and a movable display screen, achieves adaptive adjustment for users with different degrees of myopia, greatly improving the applicability of AR devices and the user experience.

[0022] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.

[0024] Figure 1This is a schematic diagram of the structure of the AR optical module provided in the embodiments of this application;

[0025] Figure 2 This is one of the MTF diagrams of the AR optical module provided in the embodiments of this application;

[0026] Figure 3 The second MTF diagram of the AR optical module provided in the embodiments of this application;

[0027] Figure 4 The third MTF diagram of the AR optical module provided in the embodiments of this application.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. First optical axis; 2. Aperture; 3. First lens; 31. First surface; 32. Second surface; 33. Third surface; 4. Display screen; 5. Light beam; 6. Second lens; 7. Polarizing reflector; 8. Polarizer; 9. Liquid lens. Detailed Implementation

[0030] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0031] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0032] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0033] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0034] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0035] The AR optical module and head-mounted display device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0036] According to one embodiment of this application, an AR optical module is provided, see [link to relevant documentation]. Figure 1The AR optical module includes a first lens 3 and a second lens 6 disposed along a first optical axis 1, wherein the first lens 3 includes a first surface 31, a second surface 32 and a third surface 33; the AR optical module also includes a liquid lens 9 and a display screen 4 disposed along a second optical axis, wherein the liquid lens 9 and the display screen 4 are located on one side of the first surface 31, and the display screen 4 is configured to be movable relative to the liquid lens 9 along the second optical axis, wherein the liquid lens 9 and the display screen 4 are used to adjust the focal length of the AR optical module according to the user's viewing angle; the second lens 6 is located on one side of the second surface 32, and a polarizing reflector 7 is disposed between the second lens 6 and the first lens 3.

[0037] The AR optical module provided in this application mainly includes the following key components.

[0038] First lens 3: The first lens 3 has at least three surfaces, see [link to documentation]. Figure 1 That is, the first surface 31, the second surface 32 and the third surface 33; wherein the third surface 33 (the side away from the aperture 2) is, for example, a free-form surface that bends toward the aperture 2, which helps to reduce the volume of the AR optical module.

[0039] The first lens 3 is used to participate in the transmission and folding of light, display the virtual image at a specific distance, and achieve a clear imaging effect through multiple reflections and transmissions of light through its surface.

[0040] Second lens 6: The second lens 6 is located on one side of the second surface 32 of the first lens 3 in the entire optical structure, and a polarizing reflector 7 is also provided between it and the first lens 3.

[0041] Polarizing reflector 7: Polarizing reflector 7 is disposed between the first lens 3 and the second lens 6. Polarizing reflector 7 is used to reflect light, and works with the total reflection surface (third surface 33) of the first lens 3 to realize the folding and transmission of light, thereby improving the energy utilization of the virtual optical path.

[0042] Liquid Lens 9: See Figure 1 The liquid lens 9 is set along another optical axis, namely the second optical axis, and is located on one side of the first surface 31 (the light incident surface of the first lens 3) of the first lens 3.

[0043] Display screen 4: Also located on one side of the first surface 31 of the first lens 3, it is adjacent to the liquid lens 9 and arranged along the second optical axis. Display screen 4 is used to display images, and the light emitted by it should be linearly polarized light; otherwise, the emitted light needs to be processed to convert it into linearly polarized light. Subsequently, the linearly polarized light undergoes optical path folding and transmission through the liquid lens 9 and the first lens 3.

[0044] This application introduces a dynamic adjustment mechanism between the liquid lens 9 and the display screen 4, enabling personalized refractive power adjustment based on the user's myopia degree. The liquid lens 9, as an advanced adjustable focusing element, allows for flexible focal length adjustment to meet the needs of users with different visual conditions. Simultaneously, the display screen 4 is designed to move back and forth along a direction perpendicular to its surface, further enhancing the accuracy of focal length adjustment.

[0045] When a user wears the AR optical module of this application for visual experience, the system containing the AR optical module, such as an AR system, first identifies and records the user's myopia degree. Subsequently, by precisely controlling the focal length change of the liquid lens 9 and adjusting the front and back position of the display screen 4, the AR optical module can present the user with a clear, distortion-free image in real time. In this process, the focal length of the liquid lens 9 is intelligently adjusted according to the user's myopia degree, while the fine-tuning of the display screen 4 ensures the optimal focus of the image, thereby achieving personalized diopter adjustment.

[0046] This design not only greatly enhances the applicability and user experience of AR optical modules, but also breaks through the limitations of traditional AR optical modules in terms of vision adaptability. Users with different visual acuity can obtain a clear visual experience through the AR optical module of this application.

[0047] It should be noted that the first lens 3 and the second lens 6 are connected in series along the first optical axis 1, and the liquid lens 9 and the display screen 4 are connected in series along the second optical axis. The first optical axis 1 and the second optical axis form a certain angle.

[0048] The AR optical module provided in this application embodiment is referred to... Figure 1 When the display screen 4 emits light, the light is first converted into linearly polarized light, then passes through the liquid lens 9 and enters the first lens 3. Inside the first lens 3, the light is folded twice and passes through the first lens 3 three times, finally undergoing total internal reflection on the third surface 33 of the first lens 3, and is reflected back to the first lens 3 by the polarizing reflector 7, ultimately entering the aperture 2 (or the human eye). By adjusting the focal length of the liquid lens 9 and the front and rear positions of the display screen 4, clear imaging can be achieved for users with different degrees of myopia.

[0049] The AR optical module provided in this application embodiment has a liquid lens 9 disposed on the light-emitting side of the display screen 4. The liquid lens 9, with its dynamic adjustment capability, can adapt to the myopia or hyperopia of different users, adjusting the focal length of the module in real time to achieve refractive power matching. This feature avoids the inconvenience of users wearing additional glasses.

[0050] The focal length adjustment function of the liquid lens 9 works in coordination with the display screen 4 and the first lens 3 (whose unique three-surface design is particularly crucial), ensuring that light is optimized at every stage of its propagation path. This not only improves light transmittance but also helps reduce aberrations and distortions, guaranteeing excellent image quality.

[0051] The AR optical module provided in this application embodiment has diversified functions and optimized structural design to maintain overall compactness and meet the needs of portable devices.

[0052] See some examples in this application. Figure 1 The AR optical module also includes a polarizer 8, which is disposed on the light-emitting surface of the display screen 4 and is used to convert the light emitted by the display screen 4 into linearly polarized light.

[0053] According to this example of the application, a polarizer 8 is also introduced into the AR optical module. The function of the polarizer 8 is to convert the natural light emitted by the display screen 4 into linearly polarized light. This conversion step is crucial in the AR optical module because it allows subsequent optical elements (such as the liquid lens 9, the first lens 3, etc.) to process and utilize this light more effectively. When linearly polarized light passes through polarization-sensitive elements such as the polarizing reflector 7, light scattering and loss are reduced, thereby improving light utilization and image clarity.

[0054] In this application, the introduction of polarizer 8 can also enhance the fusion effect of virtual and real images. Specifically, in AR (Augmented Reality) applications, the good fusion of virtual and real images is crucial. By converting the light from the display screen 4 into linearly polarized light through polarizer 8, and in conjunction with other components in the AR optical module, the propagation direction and intensity of the light can be better controlled, thereby achieving a natural transition and fusion between virtual images and real scenes, and improving the user experience.

[0055] It should be noted that natural light contains light rays of various directions and wavelengths. If these rays are directly irradiated into the human eye or optical module without processing, they may cause glare or interference. In this application, a polarizer 8 is introduced. This polarizer 8 effectively reduces the interference of light rays from other directions by selectively transmitting light rays in a specific direction (i.e., linearly polarized light), thereby improving the anti-interference capability and stability of the AR optical module.

[0056] See some examples in this application. Figure 1 The incident light folds twice within the first lens 3, thus passing through the first lens 3 three times. The focal length of the light passing through the first lens 3 three times is L1. The focal length of the AR optical module is L, and 0.8 ≤ L1 / L ≤ 1.2.

[0057] Based on this example in this application, see [link to example]. Figure 1 The incident light first passes through the first surface 31 of the first lens 3 and then enters its third surface 33. It is then reflected by the third surface 33 to the second surface 32, reflected again by the polarizer 7 on one side of the second surface 32, and then passes through the first lens 3 once more. Finally, it exits through the third surface 33 to the aperture 2 (i.e., the human eye). This means that after the light is emitted from the display screen 4, it is reflected twice inside the first lens 3 before entering the aperture 2 (the human eye), thus forming a folded path for the light. This design helps to reduce the size of the AR optical module while ensuring that the light can be transmitted to the user's eye along a predetermined path and maintaining image quality.

[0058] Based on this example in this application, see [link to example]. Figure 1 The light emitted from the display screen 4 needs to pass through the first lens 3 three times during transmission. This is because after the light is reflected inside the first lens 3, it needs to pass through the first lens 3 again before reaching the human eye. This design can achieve specific optical effects such as increasing the viewing angle, adjusting the direction of light, or improving image quality.

[0059] According to this example, the ratio of the focal length of the incident light passing through the first lens 3 three times to the focal length of the AR optical module ranges from 0.8 to 1.2 (inclusive). This ratio describes the influence of the focal length of the first lens 3 during light transmission on the overall focal length of the AR optical module. Specifically, it refers to the ratio between the total focal length of the light passing through the first lens 3 three times and the focal length of the AR optical module. This ratio, ranging from 0.8 to 1.2, means that the focal length of the first lens 3 accounts for a relatively significant proportion of the focal length of the AR optical module, while this proportion is controlled within a reasonable range to ensure overall optical performance and imaging quality.

[0060] Based on the ratio range design in this example of the application, at least the following technical effects can be achieved:

[0061] (1) Reduce the size of the AR optical module:

[0062] The design of folding light twice and passing it through three times within the first lens 3 allows the AR optical module to reduce its overall size while maintaining image quality. This is especially important for AR devices that prioritize portability and lightweight design.

[0063] (2) Optimize image quality:

[0064] By precisely controlling the number of times light folds and passes through the first lens 3, as well as the range of the focal length ratio L1 / L, the propagation path of light and image quality can be optimized. Within this specific focal length ratio range, the propagation of light within the first lens 3 is more stable, reducing aberrations and distortions, thereby improving the sharpness and accuracy of the image.

[0065] It should be noted that although this design itself does not directly involve vision adjustment, it works in conjunction with components such as the liquid lens 9 to achieve clear imaging for users with different visual acuity. The liquid lens 9 adjusts the focal length according to the user's vision, while the folding and transmission design of light within the first lens 3 ensures the stability and clarity of light during transmission. Together, these two elements enhance the applicability and user experience of the AR optical module.

[0066] In some examples of this application, the first surface 31, the second surface 32 and the third surface 33 are freeform surfaces.

[0067] Designing all three surfaces of the first lens 3 as freeform surfaces is a technical highlight of this application. This design not only improves image quality and the flexibility of optical path design, but also adapts to the needs of different application scenarios and enhances the user experience. A detailed analysis follows:

[0068] Compared to traditional spherical or aspherical lenses, freeform surfaces offer greater design freedom, enabling more precise control of light paths and reducing aberrations and distortion. In this application, all three surfaces of the first lens 3 are designed as freeform surfaces, allowing for better control of light propagation and thus improving image clarity and sharpness. This is crucial for AR optical modules, as it directly affects the quality of the image seen by the user.

[0069] The freeform surface design allows for more flexible and precise optical path design. By adjusting the parameters of the freeform surface (such as radius of curvature and surface shape), the transmission path of light can be optimized, enabling more complex optical functions. In this application, this design facilitates the folding and multiple transmission of light within the first lens 3, thereby reducing the size of the AR optical module and improving image quality.

[0070] High-quality imaging and optimized optical path design directly enhance the user's visual experience when using AR devices. Users can see clearer and more stable images. In addition, freeform lenses may help reduce glare and ghosting, further improving user comfort.

[0071] See some examples in this application. Figure 1The second surface 32 is the surface of the first lens 3 away from the aperture 2. The second surface 32 is bent toward the aperture 2, and the radius of curvature of the second surface 32 is -200mm to -50mm.

[0072] The second surface 32 of the first lens 3 is designed to be curved toward the aperture 2, and its radius of curvature is designed to be in the range of -200mm to -50mm. This design helps to reduce the size of the AR optical module.

[0073] Because the curvature direction of the second surface 32 of the first lens 3 is opposite to the direction of human eye line of sight, the propagation path of light inside the lens is more compact, thereby achieving miniaturization and weight reduction of the AR optical module. This is of great significance for improving the portability and wearing comfort of AR devices.

[0074] Specifically, when the third surface 33 of the first lens 3 bends towards the aperture 2 (actually towards the human eye), it can reduce the thickness of the first lens 3 (thickness along the first optical axis) while maintaining the necessary optical performance, thereby effectively compressing the overall volume of the AR optical module. This is crucial for AR devices that prioritize lightweight and portability. Furthermore, the freeform surface bending towards the aperture 2 (the human eye) can better guide light into the eye, reducing the transmission distance and number of reflections of light within the AR optical module, minimizing light loss, and improving optical path efficiency.

[0075] In addition, the freeform surface that bends toward the human eye helps to expand the field of view of the AR optical module, allowing users to observe a wider virtual scene.

[0076] In this example of the application, by precisely controlling the radius of curvature of the second surface 32 of the first lens 3, the refraction and reflection paths of light can be optimized, reducing light loss and distortion, thereby improving the imaging effect. This design allows light to be distributed more evenly inside the first lens 3, reducing problems such as light intensity attenuation and image blurring caused by excessively long light propagation paths. Furthermore, the specific curvature design of the second surface 32 also helps to enhance the stability of the entire AR optical module.

[0077] In this example of the application, although the design itself primarily focuses on optimizing the size and imaging quality of the AR optical module, its combination with adjustment elements such as the liquid lens 9 enables adaptation to users with different vision. The liquid lens 9 is responsible for adjusting the focal length according to the user's refractive power, while the precise design of the surface of the first lens 3 ensures the stability and clarity of light during transmission. The two complement each other, improving the applicability of the AR optical module and the user experience.

[0078] See some examples in this application. Figure 1The polarizing reflector 7 is disposed on the second surface 32; the third surface 33 is the surface of the first lens 3 near the aperture 2, and the third surface 33 is a total reflection surface.

[0079] Light is totally reflected at the third surface 33 of the first lens 3 to the polarizing reflector 7 disposed on the second surface 32, and then reflected again by the polarizing reflector 7 before passing back through the first lens 3 and finally entering the aperture 2. In this process, the utilization rate of light is significantly improved. The third surface 33 of the first lens 3 is a total reflection surface, a design that ensures that light is reflected with almost no loss, while the polarizing reflector 7 selectively reflects light according to its polarization state, further enhancing the utilization rate of light. This design helps to improve the optical efficiency of the entire AR optical module, making virtual images brighter and clearer.

[0080] For example, in this application, a 50% energy utilization rate of the virtual optical path is achieved by combining a total internal reflection surface and a polarizing reflector 7. The combined use of the total internal reflection surface and the polarizing reflector 7 achieves high energy utilization of the virtual optical path, improving the overall performance of the AR optical module.

[0081] By combining the third surface 33 (total reflection surface) of the first lens 3 with the polarizing reflector 7 disposed on the second surface 32, multiple folding and reflection of the linearly polarized light emitted from the display screen 4 are achieved. This design makes the optical path more compact, which helps to reduce the size and weight of the AR optical module.

[0082] In this application, the third surface 33 of the first lens 3 is designed as a total reflection surface, ensuring the stability and consistency of light during reflection. Simultaneously, the introduction of the polarizing reflector 7 increases the control over the polarization state of light, helping to reduce interference and distortion caused by mismatched polarization states. These measures collectively improve image quality, resulting in clearer images.

[0083] In some examples of this application, the focal length of the liquid lens 9 is L3, 40mm≤L3≤80mm, and the moving distance A of the display screen 4 along the second optical axis 10 is 0mm≤|A|≤3mm.

[0084] The parameter settings for the focal length (denoted as L3) of the liquid lens 9 and the movement distance A of the display screen 4 along the second optical axis 10 reflect considerations for user adaptability. Specifically, the focal length L3 of the liquid lens 9 is set between 40mm and 80mm (including the two endpoints of 40mm and 80mm), a range that can fully cover the myopia adjustment needs of most users (the refractive error of general users is between -5D and 0D). At the same time, the movement distance A of the display screen 4 is limited to within ±3mm, ensuring that the image can still maintain high clarity and stability when adjusting the focal length to suit different users.

[0085] According to the AR optical module provided in this application embodiment, by adjusting the focal length L3 of the liquid lens 9, the AR optical module can adapt to the myopia or hyperopia of different users in real time, providing clear imaging. The limitation on the movement distance A of the display screen 4 reduces imaging jitter and blurring caused by changes in the display screen's position. Fine-tuning the position of the display screen 4 within a limited range can further optimize the optical path, ensuring that light remains stable during transmission, thereby reducing aberrations and distortion, and improving image quality.

[0086] Users can clearly view virtual images through the AR optical module provided in this application without wearing additional glasses, greatly improving the convenience and comfort of use.

[0087] Furthermore, the focal length of the liquid lens 9 and the position of the display screen 4 can be automatically adjusted, eliminating the need for tedious manual adjustments during use and further enhancing the user experience.

[0088] See some examples in this application. Figure 1 The first lens 3 and the second lens 6 are cemented together to form a cemented lens assembly, and the transmitted light power of the cemented lens is 0.

[0089] In the AR optical module provided in this application, the first lens 3 and the second lens 6 form a cemented lens assembly. The key design feature of this cemented lens assembly is that its transmittance is 0, meaning that the cemented lens assembly does not produce any additional converging or diverging effect on the transmitted light, thereby maintaining the original path and characteristics of the light. Furthermore, the design of the cemented lens assembly helps to reduce aberrations introduced by individual lenses, such as spherical aberration and coma.

[0090] It should be noted that since the transmitted light power of the cemented lens assembly composed of the first lens 3 and the second lens 6 is 0, it will not produce any additional focusing or diverging effect on light, thereby avoiding aberration problems caused by lens power mismatch. This helps to improve the clarity of the AR optical module when displaying images, allowing users to obtain a more realistic visual experience.

[0091] The cemented lens assembly design reduces the number of components in the AR optical module, mitigating image quality issues caused by loose or misaligned components. Simultaneously, the tight bonding of the cemented surfaces contributes to improved stability and reliability of the entire AR optical module.

[0092] In addition, the bonding design of the first lens 3 and the second lens 6 can simplify the structure of the AR optical module and facilitate the assembly of the AR optical module.

[0093] In the AR optical module provided in this application, the second lens 6 and the first lens 3 are cemented together to form a cemented lens group, and the transmitted light power of the cemented lens is 0, which helps to improve the overall imaging quality; at the same time, the cemented surfaces of the second lens 6 and the first lens 3 are matched to ensure the stability of light transmission.

[0094] In some examples of this application, the surface of the second lens 6 facing away from the first lens 3 has the same shape as the third surface 33, which is the surface of the first lens 3 near the aperture 2.

[0095] In this design, the second lens 6 matches the surface profile of the first lens 3 on a specific surface, meaning that the two surfaces are consistent in shape and curvature. This design helps reduce light scattering and aberrations caused by surface mismatch, thereby improving the imaging quality of the AR optical module.

[0096] When light enters the second lens 6 from the first lens 3, the light can transition more smoothly due to the similarity of the surface shape, reducing light loss and imaging distortion caused by abrupt changes in surface shape.

[0097] In some examples of this application, the transmission axis of the polarizer 8 is perpendicular to the transmission axis direction of the polarizing reflector 7.

[0098] Both the polarizer 8 and the polarizing reflector 7 are elements used to control the direction of polarized light. The polarizer 8 allows polarized light of a specific direction to pass through while blocking polarized light of other directions. The polarizing reflector 7 reflects polarized light of a specific direction.

[0099] The polarizer 8 is, for example, a polarizing film, and the polarizing reflector 7 is, for example, a polarizing reflective film.

[0100] The transmission axis of the polarizer 8 is designed to be perpendicular to the transmission axis of the polarizing reflector 7. This means that after the light emitted from the display screen 4 becomes linearly polarized light after passing through the polarizer 8, its polarization direction will be perpendicular to the reflection direction of the polarizing reflector 7. This design ensures efficient polarization state control of the light during subsequent transmission.

[0101] When light passes through the polarizer 8 and enters the polarizing reflector 7 with a specific polarization direction, most of the light can be reflected back into the AR optical module as expected, thereby achieving efficient light energy utilization.

[0102] The AR optical module of this application is described below through a specific example.

[0103] In a specific example, see Figure 1 The AR optical module includes a first lens 3 and a second lens 6 arranged along a first optical axis 1. The first lens 3 includes a first surface 31, a second surface 32, and a third surface 33, all of which are free-form surfaces. The second surface 32 of the first lens 3 is bonded to the second lens, and a polarizing reflector 7 is provided on the bonding surface. The second surface 32 is bent toward the aperture stop 2. The third surface 33 is a total reflection surface.

[0104] The first lens 3 and the second lens 6 are cemented together to form a cemented lens assembly, and the transmitted light power of the cemented lens is 0; the surface of the second lens 6 facing away from the first lens 3 has the same surface shape as the third surface 33.

[0105] The incident light folds twice within the first lens 3, thus passing through the first lens 3 three times. The focal length of the light passing through the first lens 3 three times is L1. The focal length of the AR optical module is L, and 0.8 ≤ L1 / L ≤ 1.2.

[0106] The AR optical module also includes a liquid lens 9 and a display screen 4 arranged along the second optical axis. The liquid lens 9 and the display screen 4 are located on one side of the first surface 31. The light-emitting surface of the display screen 4 is provided with a polarizer 8. The display screen 4 can move relative to the liquid lens 9 along the second optical axis. The liquid lens 9 and the display screen 4 are used to adjust the focal length of the AR optical module according to the user's vision.

[0107] Wherein, the focal length of the liquid lens 9 is L3, 40mm≤L3≤80mm, and the moving distance of the display screen 4 along the second optical axis 10 is A, 0mm≤|A|≤3mm;

[0108] The transmission axis of the polarizer 8 is perpendicular to the transmission axis of the polarizing reflector 7.

[0109] Table 1 below shows the optical parameters for this specific example.

[0110] Table 1

[0111]

[0112] Figure 2 , Figure 3 , Figure 4 The modulation transfer function (MTF) curves of the AR optical module are shown in this specific example at 450nm, 540nm, and 610nm, respectively. Figures 2 to 4 It can be seen from this:

[0113] At a spatial frequency of 15 lp / mm, the MTF value of the AR optical module is higher than 0.7 at a wavelength of 450 nm, at a wavelength of 540 nm, and at a wavelength of 610 nm.

[0114] Specifically, the MTF (Modulation Transfer Function) value is an important indicator for measuring the optical performance of an AR optical module. It reflects the module's ability to transmit image details (i.e., high-frequency information). The higher the MTF value, the stronger the module's ability to transmit image details, and the better the image quality.

[0115] MTF value at 450nm wavelength: At a spatial frequency of 15 lp / mm, the MTF value of the AR optical module is higher than 0.7. This indicates that in the blue light region (450nm is close to the blue light wavelength), the AR optical module can transmit high-frequency details of the image well and has high imaging clarity.

[0116] MTF value at 540nm wavelength: At a spatial frequency of 15 lp / mm, the MTF value of the AR optical module is higher than 0.7. In the green light region (540nm is within the green light wavelength range), the AR optical module maintains high imaging quality, further verifying its excellent performance over a wide spectral range.

[0117] MTF value at 610nm wavelength: In the red light region (610nm is close to the red light wavelength), the MTF value of the AR optical module at a spatial frequency of 15lp / mm is still higher than 0.7. This indicates that the AR optical module can effectively transmit high-frequency information of the image in the red light band, ensuring the clarity and color reproduction of the full-color image.

[0118] In summary, Figures 2 to 4 The MTF curve analysis shows that this AR optical module has excellent imaging performance in the visible light range (especially at wavelengths of 450nm, 540nm, and 610nm), maintaining a high MTF value across different wavelengths, thus ensuring image clarity and color accuracy. This is crucial for augmented reality (AR) applications, as AR optical modules are required to accurately and clearly reproduce the fusion of virtual information and the real world.

[0119] According to another embodiment of this application, a head-mounted display device is provided, the head-mounted display device including a housing and an AR optical module as described above.

[0120] The head-mounted display device provided in this application embodiment is, for example, AR smart glasses or AR smart helmet.

[0121] The specific implementation of the head-mounted display device in this application can refer to the above-described embodiments of the AR optical module. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0122] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0123] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. An AR optical module, characterized in that, It includes a first lens (3) and a second lens (6) arranged along a first optical axis (1), wherein the first lens (3) includes a first surface (31), a second surface (32) and a third surface (33); The AR optical module further includes a liquid lens (9) and a display screen (4) arranged along a second optical axis, and the liquid lens (9) and the display screen (4) are located on one side of the first surface (31). The display screen (4) is configured to be movable relative to the liquid lens (9) along the second optical axis. The liquid lens (9) and the display screen (4) are used to adjust the focal length of the AR optical module according to the user's viewing angle. The second lens (6) is located on one side of the second surface (32), and a polarizing reflector (7) is provided between the second lens (6) and the first lens (3); The AR optical module also includes a polarizer (8), which is disposed on the light-emitting surface of the display screen (4) and is used to convert the light emitted by the display screen (4) into linearly polarized light. The incident light folds twice inside the first lens (3), thus passing through the first lens (3) three times. The focal length of the light passing through the first lens (3) three times is L1. The focal length of the AR optical module is L, and 0.8≤L1 / L≤1.

2.

2. The AR optical module according to claim 1, characterized in that, The first surface (31), the second surface (32) and the third surface (33) are freeform surfaces.

3. The AR optical module according to claim 2, characterized in that, The second surface (32) is the surface of the first lens (3) away from the aperture (2). The second surface (32) bends toward the aperture (2), and the radius of curvature of the second surface (32) is -200mm to -50mm.

4. The AR optical module according to claim 3, characterized in that, The polarizing reflector (7) is disposed on the second surface (32); The third surface (33) is the surface of the first lens (3) near the aperture (2), and the third surface (33) is a total reflection surface.

5. The AR optical module according to claim 1, characterized in that, The focal length of the liquid lens (9) is L3, 40mm≤L3≤80mm, and the moving distance of the display screen (4) along the second optical axis (10) is A, 0mm≤|A|≤3mm.

6. The AR optical module according to claim 1, characterized in that, The first lens (3) and the second lens (6) are cemented together to form a cemented lens assembly, and the transmitted light power of the cemented lens is 0.

7. The AR optical module according to claim 6, characterized in that, The surface of the second lens (6) facing away from the first lens (3) has the same shape as the third surface (33), wherein the third surface (33) is the surface of the first lens (3) near the aperture (2).

8. The AR optical module according to claim 1, characterized in that, The transmission axis of the polarizer (8) is perpendicular to the transmission axis of the polarizing reflector (7).

9. A head-mounted display device, characterized in that, include: shell; and The AR optical module as described in any one of claims 1-8.

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