Optical module and intelligent head-mounted device

Abstract

The embodiment of the invention provides an optical module and intelligent head-mounted equipment. The optical module comprises a display screen, a first lens and a second lens which are sequentially arranged along the same optical axis. The first lens is a plano-convex lens and comprises a first surface and a second surface, and the first surface is a plane and is glued with the display screen; the second lens is a meniscus lens and comprises a third surface and a fourth surface, and 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 sequentially arranged on one side of the fourth surface.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical display technology. More specifically, the embodiments of the present application relate to an optical module and an intelligent head-mounted device. Background Art

[0002] Existing VR smart headsets mostly use a monolithic, folded optical path design. While this achieves a certain degree of lightweighting, it has numerous drawbacks. First, the optical module's FOV is typically limited to less than 100°, making it difficult to meet user demands for a wider field of view. Second, the process of laminating curved lens surfaces is difficult, and the overall thickness of the lens leads to a long annealing process, impacting production efficiency. Furthermore, the total optical length (TTL) often exceeds 20mm, hindering device miniaturization. Furthermore, during assembly, the screen is easily contaminated by particles, resulting in reduced image quality. Summary of the Invention

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

[0004] In a first aspect, the present application provides an optical module. The optical module includes a display screen, a first lens, and a second lens arranged in sequence 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 glued to the display screen;

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

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

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

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

[0010] Optionally, the light splitting element is provided on the third surface;

[0011] The optical module further includes a polarizing element. The phase retarder, the polarizing reflective element, and the polarizing element form a composite film 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, among which EFL L1 is the focal length of the first lens, CA 12 is the optical effective aperture of the second surface, EFL L2 is the focal length of the second lens, CA 22 is the optically effective aperture of the fourth surface.

[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 which EFL L1 is the focal length of the first lens, EFL L2 is the focal length of the second lens, EFL Lam-L2 is the focal length of the second lens after coating, EFL ALL is the total focal length of the optical module.

[0014] Optionally, the FOV of the optical module is 110°, and 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 is the radius of curvature of the third surface, R 22 is the radius of curvature of the fourth surface, R 12 is the radius of curvature of the second surface.

[0020] Optionally, the optical module further meets the following requirements:

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

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

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

[0024] Optionally, within the entire field of view of the optical module, the spot size is less than 50 μm.

[0025] In a second aspect, the present application further provides a smart head-mounted device, the smart head-mounted device comprising:

[0026] casing; and

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

[0028] The beneficial effects of this application are:

[0029] The embodiment of the present application provides an optical module. By adopting a combination of a plano-convex lens and a meniscus lens, and matching the layout of a spectrometer, a phase retarder, and a polarized reflective element, this optical solution achieves a significant improvement in the field of view (FOV) while maintaining a small object distance (i.e., a short distance from the display screen to the lens), such as reaching 110°, providing users with a wider visual experience; and, while ensuring the imaging quality, the optical module of the embodiment of the present application effectively reduces the total optical length of the optical module, thereby making the smart head-mounted device lighter and more comfortable to wear. In summary, the optical module of the embodiment of the present application, with its ultra-short focus, large field of view, excellent imaging quality, and compact design, brings a new design solution to VR smart head-mounted devices, which has significant beneficial effects and broad application prospects.

[0030] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0033] Figure 2 A dot array diagram of an optical module provided in an embodiment of the present application;

[0034] Figure 3 Field curvature and distortion diagram of the optical module provided in an embodiment of the present application.

[0035] Description of reference numerals:

[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 retarder; 6. Polarized reflective element; 7. Polarizing element; 8. Anti-reflection film. DETAILED DESCRIPTION

[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 arrangements of components and steps, numerical expressions and numerical values ​​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 in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0039] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0040] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0041] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

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

[0043] According to one embodiment of the present application, an optical module is provided. Figure 1 The optical module includes a display screen 3, a first lens 1 and a second lens 2 arranged in sequence along the same optical axis; the first lens 1 is a plano-convex lens, the first lens 1 includes a first surface 11 and a second surface 12, the first surface 11 is a plane and is glued to the display screen 3; the second lens 2 is a meniscus lens, 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; a spectrometer element 4 is arranged between the second surface 12 and the third surface 21, and a phase retarder 5 and a polarizing reflection element 6 are sequentially arranged on one side of the fourth surface 22.

[0044] The optical module provided in the embodiment of the present application is shown in FIG. Figure 1, which at least includes a display screen 3, a first lens 1, a second lens 2, and multiple optical elements such as a beam splitter 4, a phase retarder 5, and a polarization reflection element 6. Each of the above optical components will be described below.

[0045] Display screen 3: As the light source part of the optical module of the present application, it can emit light for imaging display.

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

[0047] Specifically, the first surface 11 of the first lens 1 is flat and bonded to the light-emitting surface of the display screen 3, achieving a seamless connection. This tight fit eliminates the gap issues that can exist in traditional designs, effectively preventing the risk of tiny particles such as dust and impurities falling onto the display screen 3. In smart head-mounted devices, any minor contamination can seriously impact image quality, so this design enhances the reliability and durability of smart head-mounted devices.

[0048] It should be noted that in the optical module provided in the embodiments of this application, the display screen 3, as a core component, has a relatively fragile light-emitting surface. Once dirty, directly wiping or touching it is likely to cause irreversible damage, thereby affecting the display quality 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 maintenance cost and user risk of the product.

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

[0050] Furthermore, the plano-convex design of the first lens 1 offers several other advantages. Firstly, the alignment of the plano-convex lens's flat surface with 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. Secondly, the convex surface of the plano-convex lens performs preliminary modulation of the light, guiding it along a predetermined transmission path through its specific optical parameters, such as its curvature radius and thickness, laying the foundation for subsequent optical processing.

[0051] The second lens 2 is located on the side away from the display screen 3, see 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 the light.

[0053] The light splitting element 4 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 the light into different propagation paths.

[0054] For example, the light splitting element 4 is a semi-transmissive and semi-reflective film, which can transmit a portion of light and reflect a portion of light at the same time.

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

[0056] For example, the phase retarder 5 is a quarter wave plate.

[0057] Polarization reflection element 6: located after the phase retarder 5, capable of reflecting or transmitting light according to the polarization state of the light.

[0058] In the optical module provided in the embodiments of the present application, the combination of the beam splitter 4, the phase retarder 5, and the polarized reflector 6 forms a highly efficient folded optical path. This design not only shortens the optical module's time-to-live (TTL) but also enables multiple folding and modulation of light, thereby improving imaging quality and expanding the field of view.

[0059] Specifically, see Figure 1 When light is emitted from the display screen 3 and passes through the first lens 1 bonded to the display screen 3, it first encounters the beam splitter 4, which directs the light into different paths. This step lays the foundation for subsequent optical processing. Subsequently, a portion of the light can pass through the second lens 2 and project onto the phase retarder 5. Here, the phase retarder 5 is an optical element that can change the phase characteristics of light. By regulating the light, it changes the polarization state of the light, creating conditions for subsequent reflection and transmission. The light then encounters the polarization reflector 6, which selectively reflects or transmits the light based on its polarization state. At this time, some of the light is reflected back into the optical path by the polarization reflector 6, while the other part continues to propagate forward. In this process, the light is spatially folded during propagation. The light not only undergoes multiple folds and modulations, but also utilizes the polarization and phase properties of optical materials to achieve a dual improvement in imaging quality and field of view.

[0060] The optical module provided in the embodiments of the present application can achieve a short-focus effect. The specific analysis is as follows:

[0061] The entire optical module is sequentially provided with a display screen 3, a first lens 1 (plano-convex lens) and a second lens 2 (meniscus lens) along the same optical axis, wherein the plane surface (first surface 11) of the first lens 1 is glued 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 can be achieved, thereby enhancing the short-focus effect of the optical module; at the same time, the spectroscopic element 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 retarder 5 and the polarization reflection element 6 on the side of the fourth surface 22 of the second lens 2, so that the light can undergo multiple folding and polarization state changes inside the second lens 2. Through the multiple folding and polarization state changes of the light, the equivalent transmission path of the light can be effectively shortened, thereby achieving a short-focus effect.

[0062] The optical module provided by the embodiments of the present application can bring the following technical effects:

[0063] (1) Short-focus effect realization:

[0064] By closely fitting 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 achieving the miniaturization and short-focus effect of the optical module.

[0065] The introduction of the second lens 2 (meniscus lens) further enhances the short-focus performance by utilizing its unique shape and possible shorter focal length, so that the optical length of the entire optical module is greatly reduced while maintaining high-quality imaging.

[0066] (2) Improved imaging quality:

[0067] This application ensures that the spot size is controlled within 50μm in the full field of view through optical design, including the shape of the lens and film processing, effectively improving the clarity and resolution of the imaging.

[0068] Among them, by utilizing the combination and position layout of optical elements such as the spectrometer 4, the phase retarder 5 and the polarization reflection element 6, multiple reflections of light and changes in polarization state inside the second lens 2 are achieved, thereby improving the utilization rate of light, reducing light energy loss, and thus improving the clarity of imaging.

[0069] Furthermore, because the display screen 3 and the first lens 1 are bonded together, the risk of display screen defects caused by particles entering 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 general, the optical module provided in the embodiment of the present application adopts a combination of a plano-convex lens and a meniscus lens, and is equipped with a layout of a beam splitter 4, a phase retarder 5, and a polarizing reflective element 6. This optical solution achieves a significant improvement in the field of view (FOV) while maintaining a small object distance (i.e., a short distance from the display screen 3 to the first lens 1), for example, reaching 110° (see Figure 1 The optical module of the embodiment of the present application effectively reduces the total optical length of the optical module while ensuring imaging quality, thereby making the smart head-mounted device lighter and more comfortable to wear. In short, the optical module of the embodiment of the present application, with its ultra-short focus, large field of view, excellent imaging quality, and compact design, brings a new design solution to VR smart head-mounted devices, with significant benefits and broad application prospects.

[0071] In some examples of this application, see Figure 1 , the third surface 21 and the fourth surface 22 are both 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. Figure 1 The third surface 21 is adjacent to and spaced 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 present application, both the third surface 21 and the fourth surface 22 are curved surfaces, a design that enhances the optical performance of the optical module. Specifically, the curved surface design allows for smoother refraction and reflection of light as it passes through these two surfaces (third surface 21 and fourth surface 22), helping to reduce aberrations and distortion, thereby improving imaging quality.

[0074] The curved surface design of the lens allows for more flexible control of the propagation path of light. In this application, the curved surfaces of the second lens 2 facilitate multiple folding and polarization state transitions of light within the second lens 2, thereby shortening the equivalent focal length and achieving a short-focus effect.

[0075] Furthermore, the curved surfaces of the second lens 2 enhance the adaptability of the optical module, enabling it to meet the needs of various application scenarios. For example, in VR headsets, this design helps achieve a wider field of view, higher resolution, and lower distortion, thereby enhancing user immersion and comfort.

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

[0077] In traditional VR optical module design, the process of applying film to curved lens surfaces is quite difficult, especially when the curvature radius of the lens is small (such as less than 60mm).

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

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

[0080] The simplified lamination process reduces scrap rates due to improper processes. At the same time, the larger radius of curvature also helps reduce image quality degradation caused by uneven lamination or bubbles, thereby improving the overall product yield.

[0081] In some examples of this application, see Figure 1 , the spectroscopic element 4 is arranged on the third surface 21 ; the optical module further includes a polarizing element 7 , the phase retarder 5 and the polarizing reflective element 6 form a composite film with the polarizing element 7 and are arranged on the fourth surface 22 .

[0082] The beam splitter 4 is, for example, a semi-transmissive and semi-reflective film, the phase retarder 5 is, for example, a quarter-wave plate, the polarized reflective element 6 is, for example, a polarized reflective film, and the polarizing element 7 is, for example, a polarizing film.

[0083] The beam splitter element 4 is a semi-transparent, semi-reflective film, which is applied to the third surface 21 of the second lens 2. This allows light to be split according to a specific ratio as it passes through the third surface 21. This helps to achieve a reasonable distribution of light within the optical module, thereby optimizing the overall optical path structure. Furthermore, the composite film (including the aforementioned sequentially stacked phase retarder 5, polarizing reflective element 6, and polarizing element 7) 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 folds and polarization state transitions within the second lens 2, thereby shortening the equivalent focal length and improving imaging quality.

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

[0085] In the optical module provided in the embodiments of the present application, the combination of the beam splitter element 4 and the composite film allows light to travel a longer propagation path within 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 headsets, as the short-focus design helps reduce the size and weight of the device, improving wearing comfort and portability.

[0086] Placing the light-splitting element 4 and the composite film on both surfaces of the second lens 2 can reduce the number of steps and components in the assembly process, lowering assembly difficulty and cost. This helps improve production efficiency and reduce defect rates. For example, multiple components can be installed simultaneously in a single assembly.

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

[0088] The main function of anti-reflective coating is to increase the amount of light passing through the lens by reducing reflections from 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 direct stimulation of light to the eyes, especially in strong light environments, reduce eye fatigue, and improve the comfort of wearing VR equipment for a long time.

[0090] In addition, the anti-reflective film 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, among which EFL L1 is the focal length of the first lens 1, CA 12 is the optical effective aperture of the second surface 12, EFL L2 is the focal length of the second lens 2, CA 22 is the optically effective aperture of the fourth surface 22 .

[0092] In this example of the present application, a specific range of focal length to optical effective aperture ratio is proposed, namely 1.5<EFL L2 / CA 12 <2, and 2<EFL L1 / CA 22 <2.5, among which EFL L1 and EFL L2 are the focal lengths of the first lens 1 and the second lens 2, respectively, and CA 12 and CA 22 These are the optically effective 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). This design is mainly to expand the field of view (FOV), specifically:

[0093] (1) By controlling the ratio between the focal length of the lens and the optically effective aperture of its corresponding surface, the present 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 viewing angle, 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 distortion, and improve imaging uniformity and stability. 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 the ratio of focal length to optical effective aperture proposed in this application provides a reference and guidance for the design of 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 which EFL L1 is the focal length of the first lens 1, EFL L2 is the focal length of the second lens 2, EFL Lam-L2 is the focal length of the second lens 2 after coating, EFL ALL is the total focal length of the optical module.

[0097] In this example of the present application, an optical module design is proposed by satisfying a specific focal length condition: 18mm<EFL Lam-L2 <EFL ALL <20mm, and 4.5*EFL Lam-L2 <1.1*EFL L2 <EFL L1 , achieving the effect of controlling the total optical length (TTL) of the optical module to less than 17.5mm under a 110° field of view.

[0098] According to this example of the application, EFL Lam-L2 with EFL ALL Relationship:

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

[0100] According to this example of the 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 that the focal length of the first lens 1 (EFL L1 ) is much larger than the focal length of the second lens 2 (regardless of the EFL state without film) L2 Or the state after film application EFL Lam-L2 This design helps achieve initial light expansion at the first lens 1, while the second lens 2 is mainly responsible for further light modulation and imaging, thereby achieving a large field of view while maintaining a small total optical length.

[0102] The parameter design in this example of the present application can increase the field of view (FOV) of the optical module to 110°, which is significantly better than the FOV performance of the traditional single-piece folded optical path design (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) as it can significantly improve the wearing comfort and portability of the device.

[0104] In some examples of the present 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 example of the present application, the FOV of the optical module can be extended to 110°, while the total optical length of the optical module can be controlled below 17.5 mm.

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

[0107] Although the total optical length of the optical module is significantly shortened, this application achieves a wide field of view of 110° by optimizing the parameters of the lens. This provides users with a wider field of view and enhances the immersive and interactive experience.

[0108] In some examples of the present 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 is the curvature radius of the third surface 21, R 22 is the curvature radius of the fourth surface 22, R 12 is the curvature radius of the second surface 12 .

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

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

[0114] A reasonable curvature radius ratio design helps reduce aberrations in the lens system composed of two lenses, such as spherical aberration and coma, thereby improving image clarity and resolution. This is particularly important for smart head-mounted devices, as high-quality imaging can enhance the user's visual experience.

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

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

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

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

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

[0120] The two sets of parameters in this example of the present application are put together to achieve the following goals:

[0121] (1) Optimize the lens structure: By controlling the total thickness of the two lenses (CT L1 +CT L2 ) to the total optical length TTL is between 0.85 and 0.9, and the ratio of the center thickness of the two lenses CT L1 / CT L2 When the ratio is between 2 and 2.5, the lens system composed of the two lenses can be ensured to have a reasonable structural layout, which can maintain the rigidity and stability of the lens while avoiding unnecessary material waste and volume increase.

[0122] (2) Achieve miniaturized 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 miniaturized design of the equipment.

[0123] In a specific example of the present 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 is the curvature radius of the third surface 21, R 22 is the curvature radius of the fourth surface 22, R 12 is the curvature radius of the second surface 12, CT L1 is the center thickness of the first lens 1, CT L2 is the center thickness of the second lens 2, and TTL is the total optical length of the optical module.

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

[0130] According to this example of the present application, the central thickness CT of the first lens 1 is L1 The center thickness CT of the second lens 2 L2 The ratio CT L1 / CT L2The ratio is controlled between 2 and 2.5, which helps maintain sufficient thickness for the first lens 1 (closest to the screen) while properly controlling the thickness of the second lens 2. 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 imaging quality.

[0131] According to this example of the present application, the ratio (CTL1 + CTL2) / TTL of the total thickness of the two lenses to the total optical length (TTL) of the optical module is designed to be between 0.85 and 0.9. This condition ensures that the total thickness of all lenses accounts for the majority of the total length of the optical module, which is conducive to achieving efficient light modulation and imaging within a limited space. At the same time, by adjusting this ratio, the total optical length (TTL) of the optical module can be further controlled, achieving miniaturization and lightweighting of the optical module.

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

[0133] The proportional relationship set in this application example not only takes into account the optimization of optical performance but also the feasibility of engineering implementation. For example, by increasing the curvature radius of the second lens 2 curved surface film, the film application process can be reduced in difficulty; by properly controlling the thickness of the two lenses and the coating and film application method, the annealing process time can be reduced.

[0134] Optical modules designed with the aforementioned proportional relationships in mind offer greater stability and reliability, which helps extend product lifespan and user experience.

[0135] In some examples of the present application, the optical module has a spot size of less than 50 μm within the entire field of view.

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

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

[0138] Example 1

[0139] See also Figure 1 The optical module includes a display screen 3, a first lens 1 and a second lens 2 arranged in sequence 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 flat and glued to the display screen 3. The second surface 12 is convex and an anti-reflection film can be applied to the second surface 12.

[0141] The second lens 2 is a meniscus lens, which includes a third surface 21 and a fourth surface 22. The third surface 21 and the fourth surface 22 are curved surfaces. The third surface 21 is close to the second surface 12. The third surface 21 is plated with a light splitting element 4. The curvature radius R of the fourth surface 22 is 22 >90mm, a composite film is attached to the fourth surface 22, and the composite film includes a phase retarder 5, a polarizing reflective element 6 and a polarizing element 7 stacked in sequence;

[0142] Wherein, 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 is the curvature radius of the third surface 21, R 22 is the curvature radius of the fourth surface 22, R 12 is the curvature radius of the second surface 12, CT L1 is the center thickness of the first lens 1, CT L2 is the center thickness of the second lens 2, TTL is the total optical length of the optical module; on this basis, the optical module meets the following conditions: 18mm<EFL Lam-L2 <EFL ALL <20mm, and 4.5*EFL Lam-L2 <1.1*EFL L2 <EFL L1 , among which EFL L1 is the focal length of the first lens 1, EFL L2 is the focal length of the second lens 2, EFL Lam-L2 is the focal length of the second lens 2 after coating, EFL ALL is the total focal length of the optical module, so that when the FOV of the optical module is 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 less than 50 μm within the entire field of view.

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

[0145] Table 1

[0146]

[0147]

[0148] The optical module provided in this specific example has optical properties such as Figure 2 and Figure 3 As shown: Figure 2 is a point diagram diagram. Figure 3 This is the field curvature distortion diagram.

[0149] A spot diagram is a diffuse pattern formed when many light rays emitted from one point pass through an optical system and their intersection with the image plane is no longer concentrated at the same point due to aberrations. Instead, it forms a diffuse pattern spread over a certain range. It is used to evaluate the imaging quality of the projection optical system. Figure 2 In the optical module provided in this specific example, the maximum value of the image point in the point array diagram is less than 47 μm, which means that the optical module can maintain good imaging clarity at different viewing angles (for smart head-mounted devices, the clarity is sufficient to meet user needs).

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

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

[0152] The smart head-mounted device provided in the embodiments of the present application is, for example, a VR smart head-mounted device, such as VR smart glasses or a VR smart helmet.

[0153] The specific implementation of the intelligent head-mounted device of the embodiment of the present application can refer to the above-mentioned embodiments of the optical module, and therefore at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0154] The above embodiments focus on 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. Considering the simplicity of the text, they will not be repeated here.

[0155] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An optical module, characterized in that: It comprises a display screen (3), a first lens (1) and a second lens (2) which are arranged in sequence along the same optical axis; The first lens (1) is a plano-convex lens, comprising a first surface (11) and a second surface (12); the first surface (11) is a plane and is glued to the display screen (3); The second lens (2) is a meniscus lens, comprising a third surface (21) and a fourth surface (22), wherein the third surface (21) is close to the second surface (12); A beam splitter element (4) is arranged between the second surface (12) and the third surface (21), and a phase retarder (5) and a polarization reflection element (6) are arranged in sequence on one side of the fourth surface (22).

2. The optical module according to claim 1, characterized in that: The third surface (21) and the fourth surface (22) are both 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 light splitting element (4) is arranged on the third surface (21); The optical module further comprises a polarizing element (7), and the phase retarder (5) and the polarizing reflecting element (6) form a composite film with the polarizing element (7) and are arranged on the fourth surface (22).

5. The optical module according to claim 4, characterized in that: The optical module satisfies: 1.5<EFL L2 / CA 12 <2, and 2<EFL L1 / CA 22 <2.5, among which, EFL L1 is the focal length of the first lens (1), CA 12 is the optical effective aperture of the second surface (12), EFL L2 is the focal length of the second lens (2), CA 22 is the optically effective aperture of the fourth surface (22).

6. The optical module according to claim 4, characterized in that: The optical module meets the following requirements: 18 mm < EFL Lam-L2 <EFL ALL <20mm, and 4.5*EFL Lam-L2 <1.1*EFL L2 <EFL L1 , among which, EFL L1 is the focal length of the first lens (1), EFL L2 is the focal length of the second lens (2), EFL Lam-L2 is the focal length of the second lens (2) after film application, EFL ALL is the total focal length of the optical module.

7. The optical module according to claim 6, characterized in that: The FOV of the optical module is 110°, and the total optical length TTL of the optical module is less than 17.5 mm.

8. The optical module according to claim 6, 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 is the radius of curvature of the third surface (21), R 22 is the radius of curvature of the fourth surface (22), R 12 is the radius of curvature of the second surface (12).

9. The optical module according to claim 8, 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 is the center thickness of the first lens (1), CT L2 is the central thickness of the second lens (2), and TTL is the total optical length of the optical module.

10. The optical module according to claim 1, characterized in that: The optical module has a spot size of less than 50 μm within the entire field of view.

11. A smart head mounted device, characterized in that: include: shell; and An optical module as claimed in any one of claims 1 to 10.

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