Optical module and smart head-mounted device

Abstract

The embodiment of the application provides an optical module and an intelligent head-mounted device; wherein the optical module comprises a display screen, a first lens and a second lens arranged in sequence along the same optical axis; the first lens is a plano-convex lens, comprising a first surface and a second surface, the first surface is a plane and is glued with the display screen; the second lens is a meniscus lens, comprising a third surface and a fourth surface, the third surface is close to the second surface; a light splitting element is arranged between the second surface and the third surface, and a phase retarder and a polarization reflection element are arranged in sequence on one side of the fourth surface.

Description

Technical Field

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

[0002] Existing VR smart headsets mostly adopt a single-piece folded optical path design, which, while achieving some degree of portability, has several shortcomings. First, the field of view (FOV) of the optical module is usually limited to within 100°, making it difficult to meet users' needs for a larger field of view. Second, the curved lens coating process is difficult, and the overall lens thickness leads to a long annealing process, affecting production efficiency. At the same time, the total optical length (TTL) generally exceeds 20mm, which is not conducive to the miniaturization design of the device. In addition, during the assembly process, the screen is prone to particle contamination, resulting in a decrease in image quality. Summary of the Invention

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

[0004] In a first aspect, this application provides an optical module. The optical module includes a display screen, a first lens, and a second lens arranged sequentially along the same optical axis;

[0005] The first lens is a plano-convex lens, including a first surface and a second surface, wherein the first surface is a plane and is bonded to the display screen;

[0006] The second lens is a meniscus lens, including a third surface and a fourth surface, wherein the third surface is close to the second surface;

[0007] A beam splitting element is disposed between the second surface and the third surface, and a phase delayer and a polarization reflection element are disposed sequentially on one side of the fourth surface.

[0008] Optionally, both the third surface and the fourth surface are curved surfaces.

[0009] Optionally, the radius of curvature R of the fourth surface 22 >90mm.

[0010] Optionally, the beam-splitting element is disposed on the third surface;

[0011] The optical module further includes a polarization element, and the phase delayer and the polarization reflection element form a composite film with the polarization element and are disposed on the fourth surface.

[0012] Optionally, the optical module satisfies: 1.5 < EFL L2 / CA 12 <2, and 2 < EFL L1 / CA22 <2.5, where EFL L1 Let CA be the focal length of the first lens. 12 EFL is the optical effective aperture of the second surface. L2 CA is the focal length of the second lens. 22 The effective optical aperture of the fourth surface is given.

[0013] Optionally, the optical module satisfies: 18mm < EFL Lam-L2 <EFL ALL <20mm, and 4.5*EFL Lam-L2 <1.1*EFL L2 <EFL L1 Among them, EFL L1 EFL is the focal length of the first lens. L2 EFL is the focal length of the second lens. Lam-L2 EFL is the focal length of the second lens after coating. ALL The total focal length of the optical module is given.

[0014] Optionally, with an FOV of 110°, the total optical length (TTL) of the optical module is less than 17.5 mm.

[0015] Optionally, the optical module satisfies the following relationship:

[0016] 1.8 < R 22 / R 21 <2.2;

[0017] -1.2 < R 21 / R 12 <-1;

[0018] -1.2 < R 21 / R 12 <-1;

[0019] Among them, R 21 R is the radius of curvature of the third surface. 22 R is the radius of curvature of the fourth surface. 12 Let be the radius of curvature of the second surface.

[0020] Optionally, the optical module also satisfies:

[0021] 0.85 < (CT) L1 +CT L2 ) / TTL < 0.9;

[0022] 2 < CT L1 / CT L2 <2.5;

[0023] Among them, CT L1 The center thickness of the first lens, CT L2 The center thickness of the second lens is denoted by , and TTL is the total optical length of the optical module.

[0024] Optionally, the optical module has a spot size of <50μm across the entire field of view.

[0025] Secondly, this application also provides a smart head-mounted device, the smart head-mounted device comprising:

[0026] The outer casing; and

[0027] The optical module as described in the first aspect.

[0028] The beneficial effects of this application are as follows:

[0029] This application provides an optical module that, by employing a combination of plano-convex and meniscus lenses, along with a layout of beam splitters, phase delayers, and polarization reflectors, achieves a significant increase in field of view (FOV), reaching 110°, while maintaining a small object distance (i.e., a short distance from the display screen to the lens), providing users with a wider visual experience. Furthermore, this optical module effectively reduces the overall optical length while ensuring image quality, making the smart head-mounted device lighter and more comfortable to wear. In summary, the optical module of this application, with its ultra-short focal length, large field of view, excellent image quality, and compact design, brings a new design solution to VR smart head-mounted devices, offering significant benefits and broad application prospects.

[0030] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0032] Figure 1 The structure and optical path diagram of the optical module provided in the embodiments of this application;

[0033] Figure 2 A dot array diagram of the optical module provided in the embodiments of this application;

[0034] Figure 3 Field curvature and distortion diagrams of the optical module provided in the embodiments of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. First lens; 11. First surface; 12. Second surface; 2. Second lens; 21. Third surface; 22. Fourth surface; 3. Display screen; 4. Beam splitter; 5. Phase delayer; 6. Polarization reflector; 7. Polarization element; 8. Anti-reflection film. Detailed Implementation

[0037] 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.

[0038] 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.

[0039] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0040] 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.

[0041] 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.

[0042] The optical module and smart head-mounted device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0043] According to one embodiment of this application, an optical module is provided, see [link to relevant documentation]. Figure 1 The optical module includes a display screen 3, a first lens 1, and a second lens 2 arranged sequentially along the same optical axis; the first lens 1 is a plano-convex lens, and the first lens 1 includes a first surface 11 and a second surface 12, the first surface 11 being a plane and bonded to the display screen 3; the second lens 2 is a meniscus lens, and the second lens 2 includes a third surface 21 and a fourth surface 22, the third surface 21 being close to the second surface 12; a beam splitting element 4 is disposed between the second surface 12 and the third surface 21, and a phase delayer 5 and a polarization reflection element 6 are sequentially disposed on one side of the fourth surface 22.

[0044] The optical module provided in this application embodiment is referred to [reference needed]. Figure 1It includes at least a display screen 3, a first lens 1, a second lens 2, and multiple optical elements such as a beam splitter 4, a phase delayer 5, and a polarization reflector 6. The following describes each of the aforementioned optical devices.

[0045] Display screen 3: As the light source of the optical module of this application, it is capable of emitting light for imaging display.

[0046] First lens 1: It is located on the side close to the display screen 3, and the first lens 1 is designed as a plano-convex lens.

[0047] Specifically, the first surface 11 of the first lens 1 is a plane, which is bonded to the light-emitting surface of the display screen 3, achieving a gapless connection. This tight-fitting design eliminates the gap problems that may exist in traditional designs, thereby effectively avoiding the risk of dust, impurities, and other tiny particles falling onto the display screen 3. In smart head-mounted devices, any minute contamination can seriously affect image quality; therefore, this design enhances the reliability and durability of smart head-mounted devices.

[0048] It should be noted that in the optical module provided in this application embodiment, the display screen 3, as a core component, has a relatively fragile light-emitting surface. Direct wiping or touching it after it becomes dirty could potentially cause irreversible damage, thus affecting the display effect of the entire optical module. Given the high manufacturing precision and cost of the display screen 3, any form of physical damage will result in expensive repair or replacement costs, which undoubtedly increases the product's maintenance costs and usage risks.

[0049] Therefore, the protection of the display screen 3 was considered as one of the factors in the initial design of the optical solution of this application. By designing the first surface 11 of the first lens 1 as a plane and directly bonding it to the light-emitting surface of the display screen 3, the direct contact of the external environment with the display screen 3 is effectively isolated, thereby greatly reducing the risk of damage to it.

[0050] Furthermore, the plano-convex lens design of the first lens 1 brings several other advantages. On the one hand, the fit between the plano-convex lens and the display screen 3 ensures that light emitted from the display screen 3 can directly and efficiently enter the interior of the first lens 1, reducing light scattering and loss and improving light utilization. On the other hand, the convex surface of the plano-convex lens can be responsible for the initial modulation of light, guiding it onto a predetermined transmission path through its specific optical parameters such as radius of curvature and thickness, laying the foundation for subsequent optical processing.

[0051] Second lens 2: It is located on the side away from the display screen 3, see [link / reference] Figure 1 The second lens 2 is designed as a meniscus lens.

[0052] Specifically, the second lens 2 includes a third surface 21 and a fourth surface 22. The third surface 21 is close to the second surface 12 of the first lens 1 and receives light from the first lens 1. The fourth surface 22 is farther away from the display screen 3 than the third surface 21 and is responsible for further modulation and reflection of light.

[0053] Beam splitter 4: It is disposed between the second surface 12 of the first lens 1 and the third surface 21 of the second lens 2, and is used to split light into different propagation paths.

[0054] For example, the beam splitter 4 is a semi-transparent and semi-reflective film, which can transmit some light while reflecting some light.

[0055] Phase delayer 5: It is disposed on one side of the fourth surface 22 to adjust the phase of the light so as to cooperate with the subsequent polarization reflection element 6.

[0056] For example, the phase delayer 5 is a 1 / 4 waveplate.

[0057] Polarization reflection element 6: Located after the phase delayer 5, it can reflect or transmit light according to the polarization state of the light.

[0058] In the optical module provided in this application embodiment, the beam splitter 4, the phase delayer 5, and the polarization reflection element 6 are combined to form a highly efficient folded optical path. This design not only shortens the optical length (TTL) of the optical module but also enables multiple reflections and modulations of light, which helps to improve imaging quality and expand the field of view.

[0059] Specifically, see Figure 1 When light is emitted from the display screen 3, it passes through the first lens 1 attached to the display screen 3 and first encounters the beam splitter 4. The beam splitter 4 guides the light to different paths, laying the foundation for subsequent optical processing. Then, a portion of the light passes through the second lens 2 and is projected onto the phase retarder 5. The phase retarder 5 is an optical element capable of changing the phase characteristics of light. By controlling the light, it changes the polarization state of the light, creating conditions for subsequent reflection and transmission. Next, the light encounters the polarization reflection element 6, which selectively reflects or transmits the light according to its polarization state. At this point, a portion of the light is reflected back into the optical path by the polarization reflection element 6, while the other portion continues to propagate forward. In this process, the light undergoes spatial folding during propagation. The light not only undergoes multiple reflections and modulations but also utilizes the polarization and phase characteristics of optical materials, achieving a dual improvement in imaging quality and field of view.

[0060] The optical module provided in this application embodiment can achieve a short focal length effect. A detailed analysis follows:

[0061] The entire optical module is arranged along the same optical axis, consisting of a display screen 3, a first lens 1 (plano-convex lens), and a second lens 2 (meniscus lens). The planar surface (first surface 11) of the first lens 1 is bonded to the display screen 3, shortening the transmission distance of light from the display screen to the lens. Combined with the meniscus design of the second lens 2, a shorter focal length is achieved, enhancing the short-focal-length effect of the optical module. Meanwhile, the beam splitter 4 is arranged between the second surface 12 of the first lens 1 and the third surface 21 of the second lens 2. Combined with the phase delay 5 and polarization reflection element 6 on the fourth surface 22 side of the second lens 2, light can undergo multiple reflections and polarization state transitions within the second lens 2. Through these multiple reflections and polarization state transitions, the equivalent transmission path of light can be effectively shortened, thereby achieving the short-focal-length effect.

[0062] The optical module provided according to the embodiments of this application can bring the following technical effects:

[0063] (1) Achieving short focal length effect:

[0064] By tightly bonding the first lens 1 (plano-convex lens) to the display screen 3 (its first surface 11 is flat and glued to the display screen 3), the transmission distance of light from the display screen to the lens is significantly shortened, which is conducive to realizing the miniaturization and short focal length effect of the optical module.

[0065] The introduction of the second lens 2 (meniscus lens), with its unique shape and potentially shorter focal length, further enhances the short focal length performance, allowing the entire optical module to maintain high-quality imaging while significantly reducing the optical length.

[0066] (2) Improved image quality:

[0067] This application ensures that the spot size is controlled within 50μm across the entire field of view through optical design, including lens shape and coating treatment, effectively improving the clarity and resolution of the image.

[0068] By utilizing the combination and arrangement of optical elements such as beam splitter 4, phase delayer 5, and polarization reflection element 6, multiple reflections and polarization state changes of light are achieved inside the second lens 2, improving light utilization, reducing light energy loss, and thus enhancing image clarity.

[0069] Furthermore, since the display screen 3 and the first lens 1 are bonded together, the risk of defects caused by particles falling into the display screen during assembly is reduced. This optimization not only improves the overall reliability of the optical assembly but also significantly enhances the stability and durability of the final product, providing users with a more reliable and stable user experience.

[0070] In summary, the optical module provided in this application, by employing a combination of plano-convex and meniscus lenses, along with the arrangement of beam splitter 4, phase retarder 5, and polarization reflector 6, achieves a significant increase in field of view (FOV), such as reaching 110°, while maintaining a small object distance (i.e., a short distance from display screen 3 to first lens 1). (See [link to application]) Figure 1 With a mid-field-to-field angle θ of 55°, it provides users with a wider visual experience. Furthermore, the optical module of this embodiment effectively reduces the overall optical length while ensuring image quality, making the smart head-mounted device lighter and more comfortable to wear. In summary, the optical module of this embodiment, with its ultra-short focal length, wide field of view, excellent image quality, and compact design, brings a new design solution to VR smart head-mounted devices, with significant beneficial effects and broad application prospects.

[0071] See some examples in this application. Figure 1 Both the third surface 21 and the fourth surface 22 are curved surfaces.

[0072] The third surface 21 and the fourth surface 22 are two surfaces of the second lens 2. The second lens 2 is a meniscus lens. (See [link]) Figure 1 The third surface 21 is adjacent to and spaced apart from the second surface 12 of the first lens 1, and the fourth surface 22 is away from the second surface 12 of the first lens 1.

[0073] In this example of the application, both the third surface 21 and the fourth surface 22 are described as curved surfaces, a design that enhances the optical performance of the optical module. Specifically, the curved surface design allows light to undergo smoother refraction and reflection when passing through these two surfaces (the third surface 21 and the fourth surface 22), which helps reduce aberrations and distortions, thereby improving image quality.

[0074] The curved surface design of the lens allows for more flexible control over the propagation path of light. In this application, the curved surface design of the two surfaces of the second lens 2 helps to achieve multiple reflections and polarization state changes of light within the second lens 2, thereby shortening the equivalent focal length and achieving a short focal length effect.

[0075] Furthermore, the two surfaces of the second lens 2 are curved, which allows the optical module to be more adaptable and meet the needs of different application scenarios. For example, in VR smart head-mounted devices, this design helps to achieve a wider field of view, higher resolution, and lower distortion rate, thereby improving the user's immersion and comfort.

[0076] In some examples of this application, the radius of curvature R of the fourth surface 22 22 >90mm.

[0077] In traditional VR optical module design, the process of applying coatings to curved lenses is quite challenging, especially when the radius of curvature of the lens is small (e.g., less than 60mm).

[0078] In the optical module design provided in this application, the radius of curvature R of one surface of the second lens 2—the fourth surface 22—is... 22 Designed with a radius greater than 90mm, this parameter significantly increases the radius of curvature of the surface, making the film application process easier and reducing the technical difficulty and cost of production. Lower process difficulty and a higher yield rate help reduce product production costs and selling prices, allowing users to obtain high-quality smart head-mounted devices at more affordable prices.

[0079] It should be noted that the phase delayer 5 and the polarization reflection element 6 in this application can both be attached to the fourth surface 22 of the second lens 2.

[0080] The simplified film application process reduces the scrap rate caused by improper processes. At the same time, a larger radius of curvature helps reduce image quality degradation caused by uneven film application or air bubbles, thereby improving the overall product yield.

[0081] See some examples in this application. Figure 1 The beam splitter 4 is disposed on the third surface 21; the optical module also includes a polarization element 7, and the phase delayer 5 and the polarization reflection element 6 form a composite film with the polarization element 7 and are disposed on the fourth surface 22.

[0082] Among them, the beam splitting element 4 is, for example, a semi-transparent and semi-reflective film, the phase delayer 5 is, for example, a quarter-wave plate, the polarization reflection element 6 is, for example, a polarization reflection film, and the polarization element 7 is, for example, a polarizing film.

[0083] The beam-splitting element 4 is a semi-transparent, semi-reflective film, which is deposited on the third surface 21 of the second lens 2. This allows light to be split according to a specific ratio when passing through the third surface 21, which helps to achieve reasonable distribution of light within the optical module, thereby optimizing the overall optical path structure. Simultaneously, the composite film (including the phase retarder 5, polarization reflection element 6, and polarization element 7 stacked sequentially) can be directly attached to the fourth surface 22 of the second lens 2, further controlling the polarization state and reflection path of the light. This allows the light to undergo multiple reflections and polarization state transitions within the second lens 2, thereby shortening the equivalent focal length and improving image quality.

[0084] The composite film formed by the phase delayer 5, the polarization reflection element 6, and the polarization element 7 can precisely control the polarization direction and reflection path of light, reducing light loss and interference. This design helps to eliminate or reduce image distortion and ghosting caused by polarization mismatch, thereby improving image clarity.

[0085] In the optical module provided in this application embodiment, the combination of the beam-splitting element 4 and the composite film allows light to travel a longer propagation path inside the second lens 2, thereby achieving a shorter equivalent focal length while maintaining high-quality imaging. This is particularly important for applications such as VR smart head-mounted devices, as the short focal length design helps reduce the size and weight of the device, improving wearing comfort and portability.

[0086] By distributing the beam-splitting element 4 and the composite film onto two surfaces of the second lens 2, the number of steps and components in the assembly process can be reduced, thus lowering assembly difficulty and cost. This helps improve production efficiency and reduce defect rates. For example, multiple elements can be assembled simultaneously in a single process.

[0087] Optionally, an anti-reflective film 8 may be deposited on the second surface 12 of the first lens 1.

[0088] The main function of anti-reflective coatings is to increase the amount of light passing through a lens by reducing light reflection on the lens surface. In devices such as virtual reality (VR), increased light transmittance helps improve image brightness and clarity.

[0089] It should be noted that reducing reflected light can reduce the direct stimulation of light on the eyes, especially in bright light environments, thereby reducing eye fatigue and improving the comfort of wearing VR devices for extended periods.

[0090] In addition, anti-reflective coatings can maintain the color balance of light, reduce color distortion caused by reflection, and make the transmitted light closer to the color of the original light source, thereby improving the color reproduction of the image.

[0091] In some examples of this application, the optical module satisfies: 1.5 < EFL L2 / CA 12 <2, and 2 < EFL L1 / CA 22 <2.5, where EFL L1 CA is the focal length of the first lens 1. 12 EFL is the effective optical aperture of the second surface 12. L2 CA is the focal length of the second lens 2. 22 The effective optical aperture of the fourth surface 22 is given.

[0092] In this example of the application, a specific range of focal length to effective optical aperture ratios is proposed, namely 1.5 < EFL. L2 / CA 12 <2, and 2 < EFL L1 / CA 22 <2.5, where EFL L1 and EFL L2 These are the focal lengths of the first lens 1 and the second lens 2, respectively, while CA 12 and CA 22 These are the effective optical apertures of the second surface 12 (i.e., the rear surface of the first lens 1) and the fourth surface 22 (i.e., the rear surface of the second lens 2), respectively. This design is primarily aimed at expanding the field of view (FOV), specifically:

[0093] (1) By controlling the ratio between the focal length of the lens and the effective optical aperture of its corresponding surface, this application can effectively expand the field of view without sacrificing image quality. This design enables the optical module to provide clear images over a wider range of viewing angles, thereby improving the user experience.

[0094] (2) Within the ratio range given in the above example, the design of the two lenses can better balance the propagation characteristics of light at different angles, reduce aberrations and distortions, and improve the uniformity and stability of imaging. This is crucial for achieving a high-quality visual experience.

[0095] (3) In smart head-mounted devices, optical modules need to meet complex imaging requirements, such as large field of view, high definition, and low distortion. The range of focal length to effective optical aperture ratio proposed in this application provides a reference and guidance for designing high-performance optical modules.

[0096] In some examples of this application, the optical module satisfies: 18mm < EFL Lam-L2 <EFL ALL <20mm, and 4.5*EFL Lam-L2 <1.1*EFL L2 <EFLL1 Among them, EFL L1 EFL is the focal length of the first lens 1. L2 EFL is the focal length of the second lens 2. Lam-L2 EFL is the focal length of the second lens 2 after the coating is applied. ALL The total focal length of the optical module is given.

[0097] In this example of the application, an optical module design is proposed that satisfies a specific focal length condition: 18mm < EFL. Lam-L2 <EFL ALL <20mm, and 4.5*EFL Lam-L2 <1.1*EFL L2 <EFL L1 This achieves the effect of keeping the total optical length (TTL) of the optical module below 17.5mm in a 110° field of view.

[0098] According to this example in this application, EFL Lam-L2 With EFL ALL Relationship:

[0099] EFL Lam-L2 EFL is the focal length of the second lens 2 after the coating is applied. ALL This is the total focal length of the entire optical module. This is achieved by controlling the EFL. Lam-L2 Between 18mm and 20mm, and ensure EFL ALL Also within this range but greater than EFL Lam-L2 This can effectively balance the effect of the second lens 2 on light modulation after the film is applied and the focal length performance of the entire optical module.

[0100] According to this example in this application, EFL Lam-L2 EFL L2 With EFL L1 Relationship:

[0101] Furthermore, by setting 4.5*EFL Lam-L2 <1.1*EFL L2 <EFL L1 This condition ensures the focal length (EFL) of the first lens 1. L1 The focal length of the second lens 2 is much greater than that of the EFL (whether in the uncoated state or not). L2 EFL after applying the screen protector Lam-L2 This design helps to achieve initial beam expansion of light at the first lens 1, while the second lens 2 is mainly responsible for further modulation and imaging of light, thereby achieving a large field of view while maintaining a small overall optical length.

[0102] The parameter design in this example of the application can improve the field of view (FOV) of the optical module to 110°, which is significantly better than the FOV performance of traditional monolithic folded optical path designs (generally within 100°).

[0103] Furthermore, the optical module of this application achieves a wide field of view while keeping the total optical length (TTL) below 17.5mm through focal length control and optical layout design. This is particularly important for smart head-mounted devices (such as VR smart head-mounted devices) because it can significantly improve the wearing comfort and portability of the device.

[0104] In some examples of this application, the FOV of the optical module is 110°, and the total optical length (TTL) of the optical module is less than 17.5 mm.

[0105] According to the above examples of this application, the FOV of the optical module can be extended to 110°, while the total optical length of the optical module can be controlled to be less than 17.5 mm.

[0106] By keeping the total optical length of the optical module below 17.5mm, the entire optical module becomes more compact and lightweight. This is especially important for smart head-mounted devices (such as VR smart head-mounted devices), as smaller size and weight can significantly improve user comfort and reduce fatigue during prolonged wear.

[0107] Although the overall optical length of the optical module has been significantly shortened, this application achieves a wide field of view of 110° by optimizing the lens parameters. This provides users with a wider field of view, enhancing immersion and interactive experience.

[0108] In some examples of this application, the optical module satisfies the following relationship:

[0109] 1.8 < R 22 / R 21 <2.2;

[0110] -1.2 < R 21 / R 12 <-1;

[0111] Among them, R 21 R is the radius of curvature of the third surface 21. 22 R is the radius of curvature of the fourth surface 22. 12 The radius of curvature of the second surface 12 is given.

[0112] In this example of the application, the constraints between the radii of curvature jointly optimize the propagation path of light in the two lenses. Specifically:

[0113] By controlling the ratio R of the radii of curvature of the two surfaces (third surface 21 and fourth surface 22) of the second lens 2 22 / R 21 Between 1.8 and 2.2, and the ratio R of the radius of curvature of the third surface 21 to the second surface 2 of the first lens 1. 21 / R 12 Between -1.2 and -1, it can be ensured that light can still maintain good focusing performance and small aberrations after undergoing multiple refractions and reflections inside the two lenses.

[0114] A well-designed radius-of-curvature ratio helps reduce aberrations in a lens system composed of two lenses, such as spherical aberration and coma, thereby improving image sharpness and resolution. This is especially important for smart head-mounted devices, as high-quality imaging enhances the user's visual experience.

[0115] While maintaining image quality, optimizing the radius of curvature ratio can further reduce the overall size of the lens system composed of two lenses, achieving a compact design for the optical module. This is crucial for the portability and wearing comfort of smart head-mounted devices.

[0116] In some examples of this application, the optical module also satisfies:

[0117] 0.85 < (CT) L1 +CT L2 ) / TTL < 0.9;

[0118] 2 < CT L1 / CT L2 <2.5;

[0119] Among them, CT L1 The center thickness of the first lens 1, CT L2 The center thickness of the second lens 2 is denoted by TTL, and the total optical length of the optical module is denoted by TTL.

[0120] Based on the two sets of parameters in this example, the following objectives are achieved together:

[0121] (1) Optimize lens structure: By controlling the total thickness of the two lenses (CT) L1 +CT L2 The ratio of the optical length to the total optical length (TTL) is between 0.85 and 0.9, and the ratio of the center thicknesses of the two lenses is CT. L1 / CT L2 A value between 2 and 2.5 ensures that the lens system composed of these two lenses has a reasonable structural layout. This layout maintains the rigidity and stability of the lenses while avoiding unnecessary material waste and increased size.

[0122] (2) Achieve miniaturization design: Under the premise of meeting the lens performance and imaging quality, by optimizing the thickness and proportion of the lens, the overall size of the optical module can be further reduced, thus achieving miniaturization design of the device.

[0123] In a specific example of this application, the optical module should simultaneously meet the following four conditions:

[0124] 1.8 < R 22 / R 21 <2.2;

[0125] -1.2 < R 21 / R 12 <-1;

[0126] 0.85 < (CT) L1 +CT L2 ) / TTL < 0.9;

[0127] 2 < CT L1 / CT L2 <2.5;

[0128] Among them, R 21 R is the radius of curvature of the third surface 21. 22 R is the radius of curvature of the fourth surface 22. 12 CT is the radius of curvature of the second surface 12. L1 The center thickness of the first lens 1, CT L2 The center thickness of the second lens 2 is denoted by TTL, and the total optical length of the optical module is denoted by TTL.

[0129] Specifically, by controlling the ratio R of the radii of curvature of the two surfaces of the second lens 2 22 / R 21 The ratio R between 1.8 and 2.2, and the ratio R between the third surface 21 and the second surface 12 of the first lens 1. 21 / R 12 Between -1.2 and -1, these two conditions work together to optimize the curvature of the two surfaces of the second lens 2, helping to optimize the propagation path of light within the second lens 2. Combined with the folded optical path design, this results in a smaller effective focal length (EFL). A smaller EFL helps reduce the overall length of the optical module while maintaining good image quality.

[0130] According to this example of the application, the center thickness CT of the first lens 1 L1 With the center thickness CT of the second lens 2 L2 The ratio of CT L1 / CT L2The thickness is controlled between 2 and 2.5, which helps to reasonably control the thickness of the second lens 2 while maintaining sufficient thickness for the first lens 1 (near the screen side). By adjusting the center thickness ratio of the two lenses, the overall structure of the optical module can be optimized and made more compact while ensuring image quality.

[0131] According to this example of the application, the design with a ratio (CTL1+CTL2) / TTL of the total thickness of the two lenses to the total optical length (TTL) of the optical module between 0.85 and 0.9 ensures that the total thickness of all lenses accounts for a large portion of the total length of the optical module, which is beneficial for achieving efficient light modulation and imaging within a limited space. Furthermore, by adjusting this ratio, the total optical length (TTL) of the optical module can be further controlled, enabling miniaturization and weight reduction of the optical module.

[0132] Based on this example in the application, and taking into account engineering feasibility, the specific analysis is as follows:

[0133] The proportional relationships set in the examples of this application not only take into account the optimization of optical performance, but also the feasibility of engineering implementation. For example, by increasing the radius of curvature of the curved film on the second lens 2, the difficulty of the film application process can be reduced; by reasonably controlling the thickness of the two lenses and the coating and film application methods, problems such as annealing process time can be reduced.

[0134] Optical modules designed to meet the aforementioned proportional relationships exhibit better stability and reliability. This contributes to improved product lifespan and user experience.

[0135] In some examples of this application, the optical module has a spot size of <50μm across the entire field of view.

[0136] The optical module provided in this application embodiment has high imaging quality. The spot size is controlled within approximately 50 micrometers across the entire field of view, ensuring image clarity and providing users with a more realistic visual experience.

[0137] The present application will be described in detail below through Example 1.

[0138] Example 1

[0139] See Figure 1 The optical module includes a display screen 3, a first lens 1, and a second lens 2 arranged sequentially along the same optical axis;

[0140] The first lens 1 is a plano-convex lens, which includes a first surface 11 and a second surface 12. The first surface 11 is a plane and is bonded to the display screen 3. The second surface 12 is a convex surface, and an anti-reflective film can be attached to the second surface 12.

[0141] The second lens 2 is a meniscus lens, comprising a third surface 21 and a fourth surface 22, both of which are curved surfaces. The third surface 21 is close to the second surface 12, and a beam-splitting element 4 is deposited on the third surface 21. The radius of curvature R of the fourth surface 22 is... 22 >90mm, a composite film is attached to the fourth surface 22, the composite film including a phase retarder 5, a polarization reflection element 6 and a polarization element 7 stacked in sequence;

[0142] The optical module satisfies: 1.8 < R 22 / R 21 <2.2, -1.2<R 21 / R 12 <-1, 0.85<(CT) L1 +CT L2 ) / TTL < 0.9, 2 < CT L1 / CT L2 <2.5; R 21 R is the radius of curvature of the third surface 21. 22 R is the radius of curvature of the fourth surface 22. 12 CT is the radius of curvature of the second surface 12. L1 The center thickness of the first lens 1, CT L2 Here, is the center thickness of the second lens 2, and TTL is the total optical length of the optical module; based on this, the optical module satisfies the following condition: 18mm < EFL Lam-L2 <EFL ALL <20mm, and 4.5*EFL Lam-L2 <1.1*EFL L2 <EFL L1 Among them, EFL L1 EFL is the focal length of the first lens 1. L2 EFL is the focal length of the second lens 2. Lam-L2 EFL is the focal length of the second lens 2 after the coating is applied. ALL The total focal length of the optical module is such that, with a field of view (FOV) of 110°, the total optical length (TTL) of the optical module is less than 17.5 mm.

[0143] The optical module has a spot size of <50μm across the entire field of view.

[0144] The optical parameters of the optical module are detailed in Table 1 below.

[0145] Table 1

[0146]

[0147]

[0148] The optical module provided in this specific example has the following optical performance: Figure 2 and Figure 3 As shown: Figure 2 This is a schematic diagram of a dot-matrix diagram. Figure 3 This is a field distortion diagram.

[0149] A dot plot refers to a pattern of light rays emanating from a single point that, after passing through an optical system, intersect the image plane at a point different from the initial point due to aberrations, forming a diffuse pattern scattered over a certain area. This pattern is used to evaluate the imaging quality of the projection optical system. See also... Figure 2 The optical module provided in this specific example has a maximum image size of less than 47μm in the dot matrix diagram, which means that the optical module can maintain good image clarity at different viewing angles (the clarity is sufficient to meet the needs of users for smart head-mounted devices).

[0150] See Figure 3 The optical module provided in this specific example has a field curvature of less than 0.81 mm and an absolute distortion of less than 32.6% in the full field of view (e.g., 110°, half field of view θ is 55°). This indicates that the distortion generated during the imaging process of this optical module is small and can fully meet the imaging requirements of users for smart head-mounted devices.

[0151] According to another embodiment of this application, a smart head-mounted device is provided, the smart head-mounted device including a housing and an optical module as described above.

[0152] The smart head-mounted devices provided in this application are, for example, VR smart head-mounted devices, such as VR smart glasses or VR smart helmets.

[0153] The specific implementation of the smart head-mounted device in this application can refer to the above-described embodiments of the 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.

[0154] 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.

[0155] 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 optical module, characterized in that, It includes a display screen (3) and a lens group arranged sequentially along the same optical axis, wherein the lens group consists of a first lens (1) and a second lens (2); The first lens (1) is a plano-convex lens, including a first surface (11) and a second surface (12). The first surface (11) is a plane and is bonded to the display screen (3). The second lens (2) is a meniscus lens, including a third surface (21) and a fourth surface (22), wherein the third surface (21) is close to the second surface (12), and the convex surface of the second lens (2) faces the first lens (1); A beam splitting element (4) is disposed between the second surface (12) and the third surface (21), and a phase delayer (5) and a polarization reflection element (6) are disposed sequentially on one side of the fourth surface (22). The optical module satisfies: 1.5 < EFL L2 / CA 12 <2, and 2 < EFL L1 / CA 22 <2.5, where EFL L1 CA is the focal length of the first lens (1). 12 For the optical effective aperture of the second surface (12), EFL L2 CA is the focal length of the second lens (2). 22 The effective optical aperture of the fourth surface (22) is given.

2. The optical module according to claim 1, characterized in that, Both the third surface (21) and the fourth surface (22) are curved surfaces.

3. The optical module according to claim 2, characterized in that, The radius of curvature R of the fourth surface (22) 22 >90mm.

4. The optical module according to claim 2 or 3, characterized in that, The beam splitter (4) is disposed on the third surface (21); The optical module also includes a polarization element (7), and the phase delayer (5) and the polarization reflection element (6) form a composite film with the polarization element (7) and are disposed on the fourth surface (22).

5. The optical module according to claim 1, characterized in that, The optical module satisfies: 18mm < EFL Lam-L2 <EFL ALL <20mm, and 4.5*EFL Lam-L2 <1.1*EFL L2 <EFL L1 Among them, EFL L1 EFL is the focal length of the first lens (1). L2 EFL is the focal length of the second lens (2). Lam-L2 The focal length of the second lens (2) after coating is applied is EFL. ALL The total focal length of the optical module is given.

6. The optical module according to claim 5, characterized in that, With an FOV of 110°, the total optical length (TTL) of the optical module is less than 17.5 mm.

7. The optical module according to claim 5, characterized in that, The optical module satisfies the following relationship: 1.8<R 22 / R 21 <2.2; -1.2<R 21 / R 12 <-1; Among them, R 21 R is the radius of curvature of the third surface (21). 22 R is the radius of curvature of the fourth surface (22). 12 Let be the radius of curvature of the second surface (12).

8. The optical module according to claim 7, characterized in that, The optical properties also satisfy: 0.85<(CT L1 +CT L2 ) / TTL<0.9; 2<CT L1 / CT L2 <2.5; Among them, CT L1 The center thickness of the first lens (1), CT L2 The center thickness of the second lens (2) is TTL, and the total optical length of the optical module is TTL.

9. The optical module according to claim 1, characterized in that, The optical module has a spot size of <50μm across the entire field of view.

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

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