Optical system and intelligent head-mounted device

Abstract

The embodiment of the invention provides an optical system and intelligent head-mounted equipment. The optical system comprises an imaging assembly, a diffractive optical element and a display screen which are sequentially arranged along the same optical axis; the imaging assembly comprises a first lens, a reflection polarization element, a phase delay piece, a second lens and a light splitting element which are arranged in sequence; the first lens and the second lens are aspheric lenses; the diffractive optical element is glued with the display screen; the diffractive optical element is mainly composed of a substrate and a microstructure arranged on the substrate, and the microstructure is used for conducting phase modulation on light rays from the display screen, so that the light rays are bent and dispersed in the propagation process; through the phase modulation effect of the microstructure on the light, a chromatic aberration effect opposite to a vertical axis chromatic aberration generated by the imaging assembly can be generated. And after the light modulated by the microstructure enters the imaging assembly, the vertical axis chromatic aberration generated by the microstructure and the vertical axis chromatic aberration generated by the imaging assembly are mutually counteracted, so that the compensation of the vertical axis chromatic aberration of the imaging assembly is realized.

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 system and an intelligent head-mounted device. Background Art

[0002] With the development of virtual reality (VR) technology, VR optical display devices have been widely used in many fields. VR optical display devices provide an immersive experience, allowing users to isolate themselves from external interference and obtain a more realistic visual experience. However, most traditional VR optical systems use multiple aspheric lenses or Fresnel lenses, resulting in poor edge imaging quality and serious vertical chromatic aberration, which affects the user experience. To improve this problem, common methods include increasing the number of aspheric surfaces or using free-form surface off-axis systems, but these methods often increase the complexity and weight of the optical system. Summary of the invention

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

[0004] In a first aspect, the present application provides an optical system, the optical system comprising an imaging component, a diffractive optical element and a display screen arranged in sequence along the same optical axis;

[0005] The imaging assembly comprises a first lens, a reflective polarizing element, a phase delay plate, a second lens and a beam splitting element which are arranged in sequence;

[0006] The first lens and the second lens are both aspherical lenses;

[0007] The diffractive optical element and the display screen are glued to each other;

[0008] The diffractive optical element is mainly composed of a substrate and a microstructure arranged on the substrate, and the microstructure is used to perform phase modulation on the light from the display screen, so that the light is bent and dispersed during propagation; wherein, the phase modulation effect of the microstructure on the light can produce a chromatic aberration effect opposite to the vertical axis chromatic aberration produced by the imaging component;

[0009] When the light modulated by the microstructure enters the imaging component, the vertical axis chromatic aberration generated by the microstructure and the vertical axis chromatic aberration generated by the imaging component cancel each other out, thereby compensating for the vertical axis chromatic aberration of the imaging component and further correcting the vertical axis chromatic aberration of the optical system.

[0010] Optionally, the surface of the microstructure is a binary surface, and the expression of the binary surface is: M = (A1ρ 2 +A2ρ 4 +A3ρ 6 +A4ρ8 ), where M is the diffraction order, A1 is the quadratic phase coefficient used to correct chromatic aberration, A2, A3, A4 are aspheric phase coefficients, and ρ is the normalized polar coordinate radius.

[0011] Optionally, the diffraction order is 1, -1.07E+06≤ρ 2 ≤-1.04E+06, 2.39E+07≤ρ 4 ≤2.41E+07,-3.16E+08≤ρ 6 ≤-3.09E+08,1.04E+09≤ρ 8 ≤1.09E+09.

[0012] Optionally, the maximum thickness of the first lens is T 1Max , the minimum thickness of the first lens is T 1Mix , the first lens satisfies: 0.14<(T 1Max -T 1Mix ) / T 1Max <1;

[0013] The central thickness T2 of the second lens is: T2>8mm.

[0014] Optionally, a center thickness T1 of the first lens and a center thickness T2 of the second lens are respectively: 2mm≤T1≤10mm, 2mm≤T2≤10mm.

[0015] Optionally, a curvature radius of a surface of the first lens away from the display screen is R1, and a curvature radius of a surface of the first lens close to the display screen is R2, and R1 and R2 satisfy: 55 mm<|R1|+|R2|<80 mm.

[0016] Optionally, a curvature radius R1 of a surface of the first lens away from the display screen is -35 mm<R1<-20 mm, and a curvature radius R2 of a surface of the first lens close to the display screen is -45 mm<R2<-35 mm.

[0017] Optionally, a curvature radius R3 of a surface of the second lens close to the display screen is -40 mm<R3<-30 mm.

[0018] Optionally, the optical system satisfies: in, is the focal power of the first lens, is the focal power of the second lens, is the total optical power of the optical system.

[0019] Optionally, a straight-line distance between the first lens and an exit pupil position of the optical system is d, 0<d<15mm;

[0020] The exit pupil diameter of the optical system is D, 4mm<D<6mm.

[0021] Optionally, the total length of the optical system is L, 30 mm<L<40 mm, and the field of view FOV of the optical system is 140°<FOV<160°.

[0022] Optionally, the display screen has a size of 60 mm to 75 mm.

[0023] Optionally, the first lens and the second lens are glued to each other;

[0024] The beam splitter is arranged on a surface of the second lens close to the display screen; the phase delay plate and the reflective polarization element form a composite film material and are arranged on the bonding surface of the first lens and the second lens.

[0025] Optionally, the first lens and the second lens are made of resin material;

[0026] The first lens and the second lens are even-order aspheric lenses.

[0027] In a second aspect, the present application provides a smart head-mounted device, the smart head-mounted device comprising:

[0028] casing; and

[0029] An optical system as described in the first aspect.

[0030] The beneficial effects of this application are:

[0031] An optical system provided in an embodiment of the present application is a refractive-diffraction hybrid VR optical system with a large field of view and achromaticity. By using aspherical lenses and a variety of optical film materials to form imaging components, the various aberrations in the optical system are effectively corrected, especially the aberrations in the edge field of view, which greatly improves the imaging quality and ensures that the image seen by the user is clear and distortion-free. The entire optical system arranges a first lens, a reflective polarizing element, a phase delay plate, a second lens, a beam splitter and a diffractive optical element along the same optical axis to achieve folding and compact layout of the optical path. This design not only reduces the volume and weight of the system, but also improves the utilization rate of light. It is particularly suitable for VR devices with strict space requirements, providing users with a lighter and more comfortable wearing experience.

[0032] More importantly, the introduction of diffractive optical elements, the microstructure on which can modulate the incident light, thereby compensating for the vertical axis chromatic aberration produced by the imaging component itself. This design effectively reduces or even eliminates the vertical axis chromatic aberration of the optical system, significantly improving color reproduction and image clarity.

[0033] The bonding design of the diffractive optical element and the display not only simplifies the system structure, but also enhances the mechanical stability and durability of the optical system. This design enables the optical system to better resist external shocks and vibrations and maintain long-term stable performance.

[0034] 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

[0035] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0036] Figure 1 One of the schematic diagrams of the structure and optical path of the optical system provided in the embodiment of the present application;

[0037] Figure 2 A vertical axis aberration curve diagram of an optical system without adding a diffractive optical element;

[0038] Figure 3 for Figure 1 A vertical axis aberration curve diagram of the optical system (with added diffractive optical element) shown;

[0039] Figure 4 for Figure 1 Modulation transfer function diagram of the optical system shown (with added diffractive optical element);

[0040] Figure 5 The second schematic diagram of the structure and optical path of the optical system provided in the embodiment of the present application;

[0041] Figure 6 for Figure 5 A vertical axis aberration curve diagram of the optical system (with added diffractive optical element) shown;

[0042] Figure 7 for Figure 5 Modulation transfer function diagram of the optical system shown (with added diffractive optical element);

[0043] Figure 8 The third schematic diagram of the structure and optical path of the optical system provided in the embodiment of the present application;

[0044] Fig. 9 for Figure 8A vertical axis aberration curve diagram of the optical system (with added diffractive optical element) shown;

[0045] Fig.10 for Figure 8 Modulation transfer function diagram of the optical system shown (with added diffractive optical element);

[0046] Description of reference numerals:

[0047] 1. First lens; 2. Second lens; 3. Diffractive optical element; 4. Display screen; 5. Reflective polarizing element; 6. Phase retarder; 7. Spectral element; 01. Human eye. DETAILED DESCRIPTION

[0048] 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 of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0049] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0050] 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.

[0051] 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.

[0052] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0053] The optical system and the smart head-mounted device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0054] According to one embodiment of the present application, an optical system is provided. Figure 1 , Figure 5 and Figure 8, the optical system includes an imaging component, a diffractive optical element 3 and a display screen 4 arranged in sequence along the same optical axis; the imaging component includes a first lens 1, a reflective polarizing element 5, a phase delay plate 6, a second lens 2 and a beam splitter 7 arranged in sequence; the first lens 1 and the second lens 2 are both aspherical lenses; the diffractive optical element 3 and the display screen 4 are glued to each other; the diffractive optical element 3 is mainly composed of a substrate and a microstructure arranged on the substrate, and the microstructure is used to phase modulate the light from the display screen 4, so that the light is bent and dispersed during propagation; wherein, through the phase modulation effect of the microstructure on the light, a chromatic aberration effect opposite to the vertical axis chromatic aberration generated by the imaging component can be generated; when the light modulated by the microstructure enters the imaging component, the vertical axis chromatic aberration generated by the microstructure and the vertical axis chromatic aberration generated by the imaging component cancel each other out, thereby achieving compensation for the vertical axis chromatic aberration of the imaging component, and then achieving correction of the vertical axis chromatic aberration of the optical system.

[0055] The optical system provided in the embodiment of the present application is shown in FIG. Figure 1 , Figure 5 and Figure 8 The optical system has three major optical components arranged in sequence along the same optical axis from the human eye side (human eye 01) to the image source side (display screen 4): imaging component, diffractive optical element and display screen 4. Each optical component is described in detail below.

[0056] Regarding the design of the imaging component, it is a folded optical path structure including two lenses.

[0057] The imaging component includes a first lens 1 close to the human eye 01. The first lens 1 adopts an aspherical design and can control the refraction path of light. Compared with traditional spherical lenses, it can more effectively reduce aberrations, especially aberrations in the edge field of view, laying the foundation for high-quality imaging.

[0058] The imaging component includes a second lens 2, which also adopts an aspherical design. The second lens 2 is matched with the first lens 1, and the synergistic effect of the two aspherical lenses further corrects the aberration and improves the imaging quality.

[0059] It should be noted that the imaging component of the present application includes but is not limited to two lenses, and the number of lenses can be increased according to specific circumstances.

[0060] Optionally, the first lens 1 and the second lens 2 adopt an even-order aspheric design.

[0061] The imaging component in the present application adopts a folded optical path design, and in addition to optical lenses, also includes multiple optical elements, such as a reflective polarization element 5, a phase delay plate 6 and a spectroscopic element 7.

[0062] A reflective polarizing element (also called a polarized reflective element) is a polarized reflector that reflects horizontally polarized light and transmits vertically polarized light, or a polarized reflector that reflects linearly polarized light at any other specific angle and transmits linearly polarized light perpendicular to the angle. In other words, a reflective polarizing element can reflect or transmit light according to the polarization state of the light.

[0063] In the imaging assembly provided in the embodiment of the present application, the reflective polarizing element 5 interacts with a specific state of polarized light (such as S light or P light) to achieve specific path control of the light.

[0064] The phase retarder 6 can be used to change the polarization state of light, such as to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

[0065] The phase retarder 6 in the present application is, for example, a quarter-wave plate, which is located between the beam splitter element 7 and the reflective polarization element 5 and ensures that the light can be reflected or transmitted in the subsequent path by adjusting the phase of the light.

[0066] The light splitting element 7 is, for example, a film or coating with specific light splitting characteristics, and can be used to reflect and transmit incident light in a certain proportion.

[0067] The light splitting element 7 in the present application is, for example, a semi-transparent and semi-reflective film, which can allow a portion of light to be transmitted and another portion of light to be reflected.

[0068] It should be noted that the reflectivity and transmittance of the light splitting element 7 can be flexibly adjusted according to specific needs, and this is not limited in the embodiments of the present application.

[0069] In the optical system provided in the embodiment of the present application, the phase retarder 6 is to be located between the beam splitter 7 and the reflective polarization element 5. These three optical elements, together with the first lens 1 and the second lens 2, can form a folded optical path.

[0070] The introduction of the diffractive optical element 3 is an innovation in the optical system of the present application. The diffractive optical element 3 is mainly composed of a substrate and microstructures arranged on the substrate. These microstructures have specific shapes and arrangements and can phase modulate the incident light. Specifically, when the light passes through these microstructures, it bends and disperses. This phase modulation effect of the light is crucial for correcting the vertical axis aberration (including vertical chromatic aberration) of the entire optical system.

[0071] The diffraction phenomenon of light is that light bends and disperses when it encounters an obstacle or passes through a small hole. The diffractive optical element 3 introduced in this application uses this principle to phase modulate the incident light through the microstructure on its surface. The microstructure design on the surface of the diffractive optical element 3 can introduce a specific phase change, so that light of different wavelengths bends and disperses to different degrees during the propagation process. This phase modulation effect can accurately adjust the propagation path of the light, thereby achieving the correction of vertical axis aberration, especially vertical axis chromatic aberration.

[0072] Vertical axis aberration, such as vertical axis chromatic aberration, is caused by the focus point offset caused by different refractive indices when light of different wavelengths passes through the imaging component. The microstructure of the diffractive optical element 3 in the present application can perform phase regulation before the incident light of different wavelengths, so that they are bent and dispersed to different degrees during the propagation process, thereby ensuring that all wavelengths of light can be accurately focused on the same plane. This feature greatly improves color reproduction and image clarity, allowing users to enjoy a more realistic and natural visual effect.

[0073] In this application, see Figure 1 The diffractive optical element 3 is mainly composed of a substrate and a microstructure arranged on the substrate, and the microstructure is used to phase modulate the light from the display screen 4, so that the light is bent and dispersed during propagation; wherein, through the phase modulation effect of the microstructure on the light, a chromatic aberration effect opposite to the vertical axis chromatic aberration generated by the imaging component can be generated; when the light modulated by the microstructure enters the imaging component, the vertical axis chromatic aberration generated by the microstructure and the vertical axis chromatic aberration generated by the imaging component offset each other, thereby achieving compensation for the vertical axis chromatic aberration of the imaging component, and then achieving correction of the vertical axis chromatic aberration of the optical system.

[0074] It can be seen that the diffractive optical element 3 can correct the vertical axis aberration (including vertical axis chromatic aberration) of the imaging component to improve the color accuracy and clarity of the image. This is particularly important for VR optical display systems, because VR optical display systems formally require high color fidelity and high resolution to provide an immersive user experience.

[0075] The optical system provided in the embodiment of the present application has the following significant beneficial effects:

[0076] (1) Large field of view and anti-axis chromatic aberration design:

[0077] The optical system of the present application is designed as a large-field-of-view, achromatic refraction-diffraction hybrid VR optical system, with special emphasis on the correction of vertical axis aberrations. Specifically, by using a combination of aspheric lenses to form an imaging component, various aberrations in the optical system are effectively corrected, including but not limited to chromatic aberration (especially vertical axis chromatic aberration) and spherical aberration, coma, astigmatism and other edge field aberrations. These correction measures greatly improve the imaging quality, ensuring that the images seen by users are clear and distortion-free, and the color reproduction is accurate.

[0078] (2) Efficient optical path folding and compact layout:

[0079] The entire optical system carefully arranges the first lens 1, reflective polarization element 5, phase delay plate 6, second lens 2, beam splitter 7 and diffractive optical element 3 along the same optical axis, achieving efficient folding and compact layout of the optical path. This design not only significantly reduces the volume and weight of the optical system, but also improves the utilization rate of light. It is particularly suitable for VR devices with strict space requirements, providing users with a lighter and more comfortable wearing experience.

[0080] (3) Vertical axis chromatic aberration correction:

[0081] The introduction of the diffractive optical element 3 is a highlight of the optical system provided by the present application. The microstructure on the diffractive optical element 3 can modulate the incident light, thereby compensating for the vertical axis chromatic aberration generated by the imaging component itself. This design effectively reduces or even eliminates the vertical axis chromatic aberration of the optical system, further improves the color reproduction and image clarity, and brings a more realistic and delicate visual experience to the user.

[0082] (4) Enhance the mechanical stability and durability of the optical system:

[0083] The bonding design of the diffractive optical element 3 and the display screen 4 not only simplifies the structure of the optical system, but also enhances the mechanical stability and durability of the optical system. This is because the diffractive optical element 3 itself is relatively thin and requires additional support elements to ensure strength. In the present application, the bonding design of the diffractive optical element 3 and the display screen 4 enables the optical system to better resist external shocks and vibrations, maintain long-term stable performance, reduce the user's maintenance costs, and protect the display screen.

[0084] In summary, the optical system provided in the embodiments of the present application achieves multiple beneficial effects such as a large field of view, comprehensive elimination of vertical axis chromatic aberration, optical path folding, compact layout, and enhanced mechanical stability, which effectively improves the overall performance of VR devices.

[0085] In some examples of the present application, the surface of the microstructure is a binary surface, and the expression of the binary surface is: M = (A1ρ 2 +A2ρ4 +A3ρ 6 +A4ρ 8 ), where M is the diffraction order, A1 is the quadratic phase coefficient used to correct chromatic aberration, A2, A3, A4 are aspheric phase coefficients, and ρ is the normalized polar coordinate radius.

[0086] According to this example of the present application, by introducing the quadratic phase coefficient A1, the two-element surface design can effectively correct the vertical axis chromatic aberration (a type of vertical axis aberration) of the optical system. This has a significant effect on improving the imaging quality, especially in the scenario of multi-wavelength color imaging.

[0087] The introduction of the aspheric phase coefficients A2, A3, and A4 enables the diffractive optical element 3 to compensate for the aspheric aberration of the optical system while correcting the vertical axis chromatic aberration, that is, to perform aspheric aberration correction, which helps to improve the imaging performance of the optical system, especially in the marginal field of view area.

[0088] In addition, the two-element surface design can flexibly control the phase and intensity distribution of light by adjusting various coefficients to meet different optical design requirements, which provides more possibilities for the optimization design of optical systems.

[0089] In some examples of the present application, the diffraction order is 1, -1.07E+06≤ρ 2 ≤-1.04E+06, 2.39E+07≤ρ 4 ≤2.41E+07,-3.16E+08≤ρ 6 ≤-3.09E+08,1.04E+09≤ρ 8 ≤1.09E+09.

[0090] By strictly limiting the value range of the normalized polar coordinate radius ρ, the microstructure size and shape of the diffractive optical element 3 can be controlled, which helps to ensure that the optical performance of the diffractive optical element 3 meets the design requirements and improves the overall imaging quality of the optical system.

[0091] In a specific diffraction order, such as order 1 in this example, by optimizing the range of the normalized polar coordinate radius ρ, the diffraction efficiency of the diffractive optical element 3 can be maximized. This means that more light will be guided to a predetermined direction, thereby improving the light energy utilization rate and imaging brightness of the optical system.

[0092] Precisely controlling the microstructure parameters of the diffractive optical element 3 helps to enhance the stability of the optical system, which can reduce the sensitivity of the optical system to changes in the external environment and improve the reliability and durability of the optical system.

[0093] In summary, the above two examples of the present application significantly improve the performance of the diffractive optical element 3 in correcting vertical axis chromatic aberration, aspherical aberration, and improving light energy utilization by introducing a binary surface design and controlling the value range of the diffraction order and the normalized polar coordinate radius. These technical effects work together on the entire optical system, helping to achieve better imaging quality and user experience.

[0094] The structural design of the surface of the diffractive optical element 3 is based on a comprehensive formula, which combines Snell's law and the light deflection effect caused by the diffraction additional phase.

[0095] Specifically, the formula is: n2sinθ2-n1sinθ1=MλT, where n1 represents the refractive index of the incident medium, n2 represents the refractive index of the exiting medium, θ1 represents the incident angle of the light, θ2 represents the exiting angle of the light, M represents the diffraction order, λ represents the wavelength of the incident light, and T represents the grating period of the diffractive optical element 3. This formula quantifies the deflection of light when passing through the microstructure of the diffractive optical element, ensuring the accuracy of the optical path design.

[0096] In the technical solution provided in the embodiment of the present application, the microstructure surface of the diffractive optical element 3 adopts a Binary2 surface design, which is a surface that accurately defines the grating shape by a polynomial in a polar coordinate system. This design can introduce continuous phase changes on the cross section of the microstructure surface, thereby achieving fine control of the diffraction light focal length. The Binary2 surface not only provides a high degree of design flexibility, but also ensures the optimization of the diffraction efficiency, further enhancing the performance of the entire optical system.

[0097] Through the above design, the diffractive optical element 3 of the present application can effectively correct the vertical axis aberration and significantly improve the imaging quality of the optical system. At the same time, this surface design also provides a new technical path for the development of large field of view VR optical systems, which helps to achieve a more compact, lightweight and high-performance optical system design.

[0098] In some examples of the present application, the maximum thickness of the first lens 1 is T 1Max , the minimum thickness of the first lens 1 is T 1Mix , the first lens 1 satisfies: 0.14<(T 1Max -T 1Mix ) / T 1Max <1; the central thickness T2 of the second lens 2 is: T2>8mm.

[0099] In this example of the present application, the maximum thickness T of the first lens 1 is 1Max is the size of the thickest part of its physical structure, and the minimum thickness T 1MixBased on this, the thickness variation of the first lens 1 needs to satisfy: 0.14<(T 1Max -T 1Mix ) / T 1Max <1. This means that there is a certain proportional relationship between the thickness variation of the first lens 1 and its maximum thickness, so that the first lens 1 is neither too flat (to avoid limited optimization of optical performance) nor too steep (to avoid excessive manufacturing difficulty) in terms of shape.

[0100] Meanwhile, the central thickness T2 of the second lens 2 is designed to be greater than 8 mm. This requirement is intended to ensure that the second lens 2 has sufficient thickness to support its optical design, especially for those surfaces that contribute significantly to optical path folding and aberration correction, while maintaining structural stability and superior optical performance.

[0101] That is to say, the thickness design of the first lens 1 takes into account the thickness variation at different positions, while the second lens 2 emphasizes the sufficient thickness of its central part, both of which are intended to take into account the manufacturing feasibility and the overall performance of the system while meeting specific optical performance requirements.

[0102] In this example of the present application, the design of the first lens 1 and the second lens 2 can reduce the field curvature and distortion of the entire optical system to a certain extent.

[0103] In some examples of the present application, a center thickness T1 of the first lens 1 and a center thickness T2 of the second lens 2 are: 2 mm ≤ T1 ≤ 10 mm, 2 mm ≤ T2 ≤ 10 mm.

[0104] The lower limit of the center thickness of the lens is set at 2mm, mainly for structural strength and manufacturing process considerations. The lens needs to have a certain thickness to ensure its physical stability and durability. At the same time, a lens that is too thin may make it difficult to ensure the accuracy and flatness of the optical surface during the manufacturing process.

[0105] The upper limit of the lens center thickness is set to 10mm based on the overall size and weight of the optical system. In a VR optical system, the thickness of the lens will directly affect the overall size and weight of the system. Too thick a lens will increase the volume and weight of the system, reducing the wearing comfort and portability.

[0106] The center thickness of the lens will affect its optical properties such as focal power, aberration characteristics and transmittance. Increasing the thickness of the lens will usually enhance its focal power while keeping the refractive index of the lens material unchanged, but it may also introduce more aberrations. By designing the center thickness of the two lenses within the range of 2mm to 10mm, it is possible to control aberrations by optimizing the surface shape and material selection of each lens while ensuring sufficient focal power, ensuring that the optical performance of the optical system meets the design requirements.

[0107] In this example of the present application, the thickness range design of the two lenses helps to reduce the overall weight and volume of the optical system, thereby improving the wearing comfort of the user. The lighter weight and smaller volume can reduce the pressure on the head and face and improve the comfort of long-term wearing.

[0108] Sufficient lens thickness can ensure its structural stability and prevent deformation or breakage due to external forces during use. This is crucial to ensure the long-term stable operation of the optical system.

[0109] In addition, setting a reasonable center thickness range can reduce the manufacturing difficulty and cost of the lens. Lenses that are too thin or too thick may increase the technical difficulty and cost of the manufacturing process. Selecting a lens center thickness within the range of 2mm to 10mm can improve manufacturing efficiency and yield while ensuring performance.

[0110] It can be seen that the selection of 2 mm to 10 mm as the center thickness range of the first lens 1 and the second lens 2 is a decision made after comprehensive consideration of many factors such as structural strength, manufacturing process, optical performance and wearing comfort. This design choice helps to achieve high performance, light weight and good manufacturing feasibility of the optical system.

[0111] In some examples of this application, see Figure 1 The curvature radius of the surface of the first lens 1 away from the display screen 4 is R1, and the curvature radius of the surface of the first lens 1 close to the display screen 4 is R2, and R1 and R2 satisfy: 55mm<|R1|+|R2|<80mm.

[0112] According to this example of the present application, this condition is intended to optimize the imaging quality of the optical system and reduce the tolerance sensitivity of the optical system, thereby reducing the difficulty of processing.

[0113] See also Figure 1, R1 and R2 refer to the curvature radii of the two surfaces of the first lens 1, respectively. Specifically, R1 refers to the curvature radius of the surface of the first lens 1 close to the human eye side (close to the human eye 01), and R2 refers to the curvature radius of the surface of the first lens 1 close to the image source side (close to the display screen 4). The curvature radii of the two surfaces of the first lens 1 are both negative. |R1|+|R2| represents the sum of the absolute values ​​of R1 and R2, that is, the sum of the absolute values ​​of the curvature radii of the two surfaces.

[0114] Furthermore, 55mm<|R1|+|R2|<80mm. This condition limits the range of the sum of the absolute values ​​of R1 and R2, which cannot be too small or too large.

[0115] A too small |R1|+|R2| value may cause the surface of the first lens 1 to be too steep, increase the difficulty of manufacturing, and may introduce larger aberrations, affecting the imaging quality.

[0116] A too large |R1|+|R2| value may make the surface of the first lens 1 too flat and unable to effectively converge or diverge light, which will also affect the imaging quality and may increase the total volume and weight of the optical system.

[0117] By setting a suitable curvature radius range, it can be ensured that the first lens 1 can effectively converge or diverge light, thereby improving the imaging quality of the entire optical system. A suitable curvature radius helps to correct various aberrations, such as chromatic aberration, spherical aberration, etc., making the final image clearer and sharper.

[0118] It should be noted that the tolerance sensitivity of an optical system refers to the sensitivity of the optical system to errors during the manufacturing and assembly processes.

[0119] By optimizing the curvature radius of the lens included in the optical system, the sensitivity of the optical system to errors can be reduced, so that even if there are certain manufacturing and assembly errors, the optical system can still maintain good imaging performance. This helps to reduce processing difficulty and cost, and improve product yield and consistency.

[0120] The condition of 55mm<|R1|+|R2|<80mm proposed in this example of the present application reduces the tolerance sensitivity and processing difficulty of the optical system while improving the optical imaging quality by optimizing the curvature radius range of the first lens 1. This is of great significance for the development of high-performance, low-cost large-field VR optical systems.

[0121] In some examples of this application, see Figure 1The curvature radius R1 of the surface of the first lens 1 away from the display screen 4 is -35mm<R1<-20mm, and the curvature radius R2 of the surface of the first lens 1 close to the display screen 4 is -45mm<R2<-35mm.

[0122] According to this example of the present application, the curvature radii of the two surfaces of the first lens 1 are R1 and R2, respectively, and the range of R1 is -35mm<R1<-20mm, and the range of R2 is -45mm<R2<-35mm. By setting R1 and R2 within the above range, it can be ensured that the first lens 1 has moderate convergence and divergence effects on light, neither too strong nor too weak, thereby optimizing the imaging quality. The appropriate curvature radius helps to reduce aberrations, such as chromatic aberration, spherical aberration, etc., and improve the clarity and contrast of the image.

[0123] Under the premise of satisfying the imaging quality, by setting a reasonable curvature radius range, the size of the first lens 1 can be controlled, and then the size of the entire optical system can be controlled. This helps to achieve a compact and lightweight design of the optical system and improve user experience.

[0124] In addition, setting a reasonable curvature radius range helps improve the manufacturing feasibility of the lens. A curvature radius that is too large may cause the lens surface to be too flat, increasing the difficulty of manufacturing; while a curvature radius that is too small may make the lens surface too steep, also increasing the difficulty of manufacturing.

[0125] In some examples of this application, see Figure 1 , the curvature radius R3 of the surface of the second lens 2 close to the display screen 4 is -40mm<R3<-30mm.

[0126] The second lens 2 is one of the important components in the optical system, and the setting of its curvature radius R3 has an important influence on the imaging quality. By setting R3 within the range of this example of the present application, it can be ensured that the second lens 2 works in coordination with the first lens 1, further reducing aberrations and improving imaging quality.

[0127] The range of the curvature radius R3 provided in this example of the present application helps to enhance the stability of the optical system. When the curvature radius R3 of the second lens 2 is within a reasonable range, the sensitivity of the optical system to the external environment is reduced, such as the impact of changes in temperature, humidity, etc. on the imaging quality is reduced.

[0128] The design of the curvature radius of the first lens 1 and the second lens 2, especially the design that the curvature radius of both surfaces of the first lens 1 is negative, and the curvature radius of the surface of the second lens 2 close to the image source is negative, has the following advantages:

[0129] (1) Ability to optimize imaging quality

[0130] The two surface curvature radii of the first lens 1 are both negative, which means that the first lens 1 is a double concave lens. This design helps to converge the light emitted from the display screen 4 on the image source side, so that the light is properly focused before entering the human eye 01, thereby reducing aberrations and improving imaging quality. Especially for a large field of view optical system, the design of the double concave lens can better correct the aberration of the edge field of view and improve the overall visual experience.

[0131] The curvature radius of the surface of the second lens 2 close to the image source is negative, indicating that the surface is a concave surface, which helps to further converge or adjust the light emitted from the display screen 4, and works together with the first lens 1 to jointly optimize the imaging quality.

[0132] (2) Realize compact system design

[0133] The design of negative curvature radius usually means that the lens surface tends to be more concave, which helps to reduce the thickness of the lens, thereby making the entire optical system more compact while achieving the same optical performance. For VR optical display devices, compact design not only helps to improve wearing comfort, but also reduces the size and weight of the device, making it easier to use and carry.

[0134] It can be seen that the design that the curvature radius of the two surfaces of the first lens 1 is negative, and the curvature radius of the surface of the second lens 2 close to the image source is negative, has obvious advantages in optimizing imaging quality, compact design and improving visual experience.

[0135] In some examples of the present application, the optical system satisfies: in, is the focal length of the first lens 1, is the focal length of the second lens 2, is the total optical power of the optical system.

[0136] When the optical system satisfies This condition ensures that the sum of the focal powers of the first lens 1 and the second lens 2 is within a reasonable ratio to the total focal power of the optical system. This optimized focal power distribution helps balance the imaging contributions of each lens, avoids a single lens from taking on too many imaging tasks, and thus reduces the generation of aberrations.

[0137] Under the condition of a large field of view, light is incident on various surfaces of the optical system at a larger angle. By reasonably allocating the optical power of the first lens 1 and the second lens 2, the light can be refracted and focused more smoothly when passing through the two lenses, thereby reducing the incident angle of the light on various surfaces of the optical system. A lower incident angle helps to reduce reflection and scattering, and further improve the transmittance of light.

[0138] A lower light incident angle is beneficial for correcting various aberrations, especially off-axis aberrations. Off-axis aberrations are a common problem in large field of view optical systems, which can cause blurring and distortion at the edges of the image. By optimizing the distribution of optical power and reducing the light incident angle, the optical system in this application can better correct off-axis aberrations and improve the imaging quality of the entire field of view.

[0139] Spot size is one of the important indicators for measuring the imaging quality of an optical system. A smaller spot size means that the image points are more concentrated and the image is clearer. By optimizing the distribution of optical power and improving aberration correction, the optical system in this application can effectively reduce the spot size and improve the resolution and contrast of the image.

[0140] when When it is less than 0.15, it means that the sum of the optical powers of the first lens 1 and the second lens 2 is relatively small, which may lead to insufficient correction of aberrations and reduced image quality, especially under large field of view conditions. Smaller optical power distribution may also increase the sensitivity of the optical system to manufacturing tolerances and assembly errors. Minor manufacturing deviations or improper assembly may have a significant impact on image quality and increase production difficulty and cost.

[0141] when When it is greater than 0.2, the sum of the optical powers of the first lens 1 and the second lens is relatively large, which may mean that more lenses or optical elements are needed to balance the optical power of the optical system, which will increase the complexity and volume of the optical system and is not conducive to achieving a compact design.

[0142] More lenses or optical elements mean higher material costs and manufacturing costs. In addition, complex optical systems may also require more sophisticated assembly and debugging processes, further increasing costs.

[0143] Larger focal power distribution may increase the incident angle of light on each lens surface, thereby increasing the difficulty of aberration correction. Especially under large field of view conditions, the aberration of the edge field of view may be more serious, affecting the image quality. Larger incident angles may also cause more light to be reflected and scattered on the lens surface, causing light loss. This will not only reduce the transmittance of light, but may also introduce additional stray light, affecting the image quality.

[0144] Therefore, the example proposed in this application This range is based on comprehensive consideration of the optical system performance.

[0145] In some examples of the present application, the straight-line distance between the first lens 1 and the exit pupil position of the optical system is d, 0<d<15mm; the exit pupil diameter of the optical system is D, 4mm<D<6mm.

[0146] Setting the straight-line distance d between the first lens 1 and the exit pupil position of the optical system within the range of 0<d<15mm helps to achieve a compact design of the optical system. A smaller d value means that the optical path can be folded more compactly, reducing the overall length and volume of the optical system, making it more suitable for space-constrained application scenarios such as VR optical display devices.

[0147] For VR optical display devices, smaller optical system size and weight can significantly improve the wearing comfort of users. The compact optical design can reduce the pressure and discomfort of the device on the face, allowing users to wear VR optical display devices for longer and more comfortably.

[0148] In this example of the present application, the exit pupil diameter D is set within the range of 4mm<D<6mm, ensuring that the optical system can provide a larger exit pupil diameter. A larger exit pupil diameter can accommodate the variation in pupil distance of different users, reduce the black edge phenomenon during viewing, and improve the continuity and immersion of the visual experience.

[0149] In some examples of the present application, the total length of the optical system is L, 30 mm<L<40 mm, and the field of view FOV of the optical system is 140°<FOV<160°.

[0150] The optical system provided in the embodiment of the present application has a total system length L between 30 mm and 40 mm, which ensures the compactness of the optical system as a whole. In VR optical display devices, a compact optical system means a smaller device size and weight, which is crucial to improving the wearing comfort of users.

[0151] The optical system provided in the embodiment of the present application has a field of view FOV set between 140° and 160°, achieving the design goal of a large field of view. A larger field of view can provide users with a wider field of view and enhance the immersiveness of virtual reality.

[0152] Compared with the traditional optical system based on folded optical path, the FOV of the optical system of the present application can be increased to 1.5 times or more of the FOV of the traditional optical system. In VR applications, a large field of view is particularly important because it can reduce the distortion and blur of the edge field of view when the user is watching, and improve the overall visual experience.

[0153] In the optical system provided in the embodiment of the present application, see Figure 1 The display screen 4 is located at the image source side, and the display screen 4 is used to emit light for imaging display.

[0154] Optionally, a screen protection glass may be provided on the light-emitting surface of the display screen 4 .

[0155] The screen protection glass can effectively isolate external dust, fingerprints and other dirt, thereby keeping the surface of the display screen 4 clean. This is crucial for the optical system, because any dirt on the screen surface may affect light transmission and image quality. The screen protection glass can not only isolate dirt, but also effectively prevent the display screen 4 from physical damage such as scratches and collisions. This is of great significance for extending the service life of the display screen 4 and improving the overall durability of the device.

[0156] In some examples of the present application, the size of the display screen 4 is 60 mm to 75 mm.

[0157] The size of the display screen 4 is designed mainly to match the large field of view effect. Such a size not only provides a wider field of view, allowing users to immerse themselves in a more realistic and three-dimensional visual experience, but also ensures that the image details are fully displayed, so that every subtle detail can be clearly seen. At the same time, the large-size display screen can better match the overall design of the optical system, optimize the light propagation path, reduce aberrations, and further improve the imaging quality.

[0158] In some examples of this application, see Figure 1 The first lens 1 and the second lens 2 are glued to each other; the splitter element 7 is arranged on the side surface of the second lens 2 close to the display screen 4; the phase delay plate 6 and the reflective polarization element 5 form a composite film material and are arranged on the glued surface of the first lens 1 and the second lens 2.

[0159] In the imaging assembly provided in this application, see Figure 1 The spectroscopic element 7 can be arranged on the surface of the second lens 2 on one side close to the display screen 4 by plating or bonding; the phase delay plate 6 and the reflective polarizing element 5 form a composite film material and are arranged on the bonding surface of the first lens 1 and the second lens 2 by bonding.

[0160] The beam splitter 7 is, for example, a semi-transmissive and semi-reflective film (BS), the phase retarder 6 is, for example, a quarter wave plate (QWP), and the reflective polarization element 5 is a polarized reflective film (RP).

[0161] In this example of the present application, the imaging assembly is a glued assembly, and all optical elements are glued together, which simplifies the assembly process. At the same time, the gluing of the first lens 1 and the second lens 2, that is, the gluing of two aspherical lenses, is also conducive to reducing chromatic aberration and improving image quality.

[0162] In some examples of the present application, the first lens 1 and the second lens 2 are made of resin material; the first lens 1 and the second lens 2 are even-order aspheric lenses.

[0163] Optionally, the first lens 1 and the second lens 2 are both made of optical resin material, and their refractive indices n are 1.5<n<1.6, and their Abbe numbers v are 55<v<57.

[0164] The first lens 1 and the second lens 2 are made of optical resin material. Compared with traditional glass materials, resin materials have lower density, so they can significantly reduce the overall weight of the entire optical system. In VR optical display devices, reducing weight is crucial to improving user wearing comfort and reducing the burden on the neck and head.

[0165] Resin materials have good processability and are easy to mass-produce through processes such as injection molding. This not only reduces the difficulty of lens processing, but also improves production efficiency and helps reduce production costs. In addition, the easy processability of resin materials also makes the surface shape of the lens more flexible and diverse, making it easier to achieve aspheric design.

[0166] In this example of the present application, both the first lens 1 and the second lens 2 are even-order aspheric lenses. The even-order aspheric design can provide a more flexible optical surface shape, thereby better correcting aberrations and improving imaging quality. Compared with spherical lenses, aspheric lenses have significant advantages in correcting aberrations, especially at large field angles. Aspheric lenses can significantly reduce aberrations such as field curvature and distortion, providing a clearer and more realistic visual experience.

[0167] In this application, the imaging quality of the optical system is further improved by combining the low dispersion characteristics of the resin material with the even-order aspheric design. The low dispersion of the resin material helps to reduce chromatic aberration, while the even-order aspheric design can correct other types of aberrations. This design enables the optical system to maintain good imaging performance over a wider wavelength range, providing more realistic color reproduction and detail performance.

[0168] VR optical display devices need to support a larger field of view to provide an immersive visual experience. The design of even-order aspheric lenses can better meet the needs of a large field of view, reduce aberrations and distortions in the edge field of view, and provide uniform imaging quality. At the same time, the lightweight and easy processing of resin materials also help to achieve a more complex optical system structure to meet the dual needs of VR devices for high imaging quality and lightness.

[0169] See also Figure 1 , Figure 5 and Figure 8 , the light transmission path of the optical system provided in the embodiment of the present application is as follows:

[0170] The left-handed circularly polarized light from the display screen 4 is first modulated by the diffractive optical element 3 and then incident on the right surface of the second lens 2 (the surface close to the display screen 4). After half of the light is transmitted by the beam splitter 7, it is incident on the left surface of the second lens 2 (the surface close to the human eye 01). The left surface of the second lens 2 is attached with the phase delay plate 6 and the reflective polarizing element 5. The left-handed circularly polarized light first passes through the phase delay plate 6 to become vertical linear polarized light. When it is incident on the reflective polarizing element 5, the reflective polarizing element 5 has a reflective vertical linear polarized light. According to the characteristics of polarized light, the light is reflected and passes through the phase retarder 6 again to become left-handed circularly polarized light, and is transmitted through the second lens 2 and reflected at the beam splitter 7 to become right-handed polarized light; the right-handed polarized light passes through the second lens 2 again and is converted into horizontal linear polarized light by the phase retarder 5. At this time, the reflective polarizing element 5 no longer reflects it, so that it can continue to be transmitted to the first lens 1, and is refracted by the right surface (the surface close to the display screen 4) and the left surface (the surface close to the human eye 01) of the first lens 1 in turn, and finally enters the human eye 01 to form an image.

[0171] In the present application, the diffractive optical element 3 is designed to adopt the first order of diffraction and specially optimize its coefficient structure, wherein the maximum coefficient is as high as 4. Before the diffractive optical element 3 is introduced, the vertical axis aberration of the optical system is quite significant. Specifically, see Figure 2 , Figure 2 FIG. 1 shows an optical module without the diffractive optical element 3. It can be clearly seen that the vertical axis aberration of the optical system exceeds 160 μm. However, by introducing the diffractive optical element 3 into the optical system, Figure 3 , greatly reducing the vertical axis aberration of the optical system to below 30μm, achieving a significant aberration correction effect.

[0172] The optical system provided in the embodiment of the present application shows excellent performance in color control, and its maximum chromatic aberration is controlled within 25μm. Compared with the traditional VR optical system, the present application has made significant progress in improving the quality of multi-wavelength color imaging. In addition, the modulation transfer function (MTF) of the optical system can still maintain an excellent level above 0.3 at a spatial frequency of 30 line pairs / mm, further demonstrating its outstanding ability in high-resolution imaging.

[0173] From the perspective of combining the optimization of the imaging component with the diffractive optical element 3, the optical system of the present application has the following beneficial effects:

[0174] From the perspective of the benefits of imaging component optimization:

[0175] The imaging component adopts a design of aspheric lenses glued together, which can effectively correct various aberrations in the optical system, such as spherical aberration, coma, astigmatism, etc., especially the aberration of the edge field of view. Compared with traditional spherical lenses, aspheric lenses have higher design freedom and can more accurately control the propagation path of light, thereby significantly improving the imaging quality and ensuring clear and distortion-free images.

[0176] The tight bonding of the internal components of the imaging assembly not only simplifies the system structure, but also realizes efficient folding and compact layout of the optical path, reducing the volume and weight of the system. This compact layout makes the entire optical system more suitable for occasions with strict space requirements, such as VR equipment.

[0177] From the benefits brought by the introduction of diffractive optical element 3:

[0178] The microstructure on the diffractive optical element can modulate the incident light and produce a chromatic aberration effect opposite to the vertical axis chromatic aberration produced by the imaging component, thereby compensating for the vertical axis chromatic aberration. This compensation mechanism effectively reduces or even eliminates the vertical axis chromatic aberration of the optical system, significantly improves color reproduction and image clarity, and makes the images seen by users more realistic and delicate.

[0179] The bonding design of the diffractive optical element and the display enhances the mechanical stability and durability of the system, making the optical system better able to withstand external shocks and vibrations. This improved stability ensures that the optical system maintains stable performance output during long-term use.

[0180] The combination of the optimization of the imaging assembly and the diffractive optical element 3 realizes the comprehensive correction of various aberrations (including chromatic aberration, spherical aberration, coma, astigmatism, etc.), significantly improving the imaging quality of the optical system. Users can enjoy clearer, distortion-free, and accurate color reproduction images. The compact layout of the imaging assembly and the introduction of the diffractive optical element make the entire optical system more efficient and stable. The optical system of the present application can better adapt to various use environments and conditions and maintain long-term stable performance output.

[0181] In summary, the optical system of the present application achieves a comprehensive improvement in imaging quality and enhancement of system performance and stability through the optimization of imaging components and the combination of diffractive optical elements, providing a more excellent optical solution for application scenarios such as VR equipment.

[0182] The optical system provided by the present application is further described below through Examples 1 to 3.

[0183] Example 1

[0184] See also Figure 1 The optical system provided in this embodiment 1 includes a first lens 1, a reflective polarizing element 5, a phase retarder 6, a second lens 2, a beam splitter 7, a diffractive optical element 3 and a display screen 4, which are arranged in sequence along the same optical axis from the human eye side to the image source side;

[0185] The first lens 1 and the second lens 2 are even-order aspheric lenses, the first lens 1 and the second lens 2 are glued to each other and both are made of resin material;

[0186] The light splitting element 7 is arranged on a side surface of the second lens 2 close to the image source surface;

[0187] The phase retarder 6 and the reflective polarizing element 5 form a composite film and are arranged on the bonding surface of the first lens 1 and the second lens 2;

[0188] The diffractive optical element 3 is mainly composed of a substrate and a microstructure arranged on the substrate, and the microstructure can modulate the incident light so that the light is bent and dispersed during propagation, thereby correcting vertical axis chromatic aberration;

[0189] The display screen 4 emits light for imaging display, and the diffractive optical element 3 and the light-emitting surface of the display screen 4 are glued to each other.

[0190] Table 1 shows the surface parameters of each element of the optical system of this embodiment 1.

[0191] Table 1

[0192]

[0193]

[0194] With reference to Table 1: S1 is the surface of the first lens 1 close to the human eye 01 (left surface), and S2 is the surface of the first lens 1 close to the display screen 4 (right surface);

[0195] S3 is the reflective polarization element 5, and S4 is the phase delay plate 6;

[0196] S5 is the surface of the second lens 2 close to the human eye 01 (left surface), and S6 is the surface of the second lens 2 close to the display screen 4 (right surface);

[0197] S7 is the surface of the diffractive optical element 7 close to the human eye 01 (left surface), and S8 is the surface of the diffractive optical element 3 close to the display screen 4 (right surface).

[0198] Table 2 shows the aspheric high-order coefficients.

[0199] Table 2

[0200] Serial number 4th 6th 8th 10th 12th 14th 16th S1 -3.41E-05 -2.32E-06 1.62E-08 -1.15E-11 -7.83E-14 -1.10E-15 4.18E-18 S2 -9.59E-05 1.00E-07 8.97E-11 -1.77E-12 -1.05E-14 7.80E-17 -1.14E-19 S5 -1.68E-05 -6.00E-09 -3.09E-11 1.08E-13 -5.86E-16 1.48E-18 -1.57E-21

[0201] Table 3 shows various coefficients of the microstructure surface of the diffractive optical element.

[0202] Table 3

[0203] Diffraction order Maximum number of terms <![CDATA[ρ 2 Item]]> <![CDATA[ρ 4 Item]]> <![CDATA[Ρ 6 Item]]> <![CDATA[Ρ 8 Item]]> 1 4 -1.05E+06 2.41E+07 -3.16E+08 1.08E+09

[0204] Figure 2 This is a vertical axis aberration curve of the optical system before adding a diffractive optical element. It can be clearly seen that the vertical axis aberration of the optical system exceeds 160μm.

[0205] See also Figure 1 In the optical system of this embodiment 1, a diffractive optical element 3 is introduced, see Figure 3 The vertical axis aberration curve of the optical system provided in Example 1 shows that the vertical axis aberration of the optical system is 26.7 μm, that is, the vertical axis aberration of the optical system is greatly reduced to below 30 μm, achieving a significant aberration correction effect.

[0206] Figure 4 for Figure 1 As shown in the modulation transfer function diagram of the optical system, the MTF average value of the optical system provided by this embodiment 1 is greater than 0.3 at 60lp / mm.

[0207] Example 2

[0208] See also Figure 5The optical system shown in this embodiment 2 includes a first lens 1, a reflective polarizing element 5, a phase retarder 6, a second lens 2, a beam splitter 7, a diffractive optical element 3 and a display screen 4, which are arranged in sequence along the same optical axis from the human eye side to the image source side;

[0209] The first lens 1 and the second lens 2 are even-order aspheric lenses, the first lens 1 and the second lens 2 are glued to each other and both are made of resin material;

[0210] The light splitting element 7 is arranged on a side surface of the second lens 2 close to the image source surface;

[0211] The phase retarder 6 and the reflective polarizing element 5 form a composite film and are arranged on the bonding surface of the first lens 1 and the second lens 2;

[0212] The diffractive optical element 3 is mainly composed of a substrate and a microstructure arranged on the substrate, and the microstructure can modulate the incident light so that the light is bent and dispersed during propagation, thereby correcting vertical axis chromatic aberration;

[0213] The display screen 4 emits light for imaging display, and the diffractive optical element 3 and the light-emitting surface of the display screen 4 are glued to each other.

[0214] The optical architecture of the optical system shown in this embodiment 2 is basically the same as the optical architecture of the optical system shown in the above-mentioned embodiment 1. Please refer to Tables 4 to 6 for the differences.

[0215] Table 4 shows the surface parameters of each element of the optical system of this embodiment 2.

[0216] Table 4

[0217] Serial number Surface type Curvature radius (mm) Thickness(mm) Refractive Index Abbe number S1 even aspherical surface -31 2.6 1.5447 56.251 S2 even aspherical surface -40 0.1 / / S3 even aspherical surface -40 0.1 1.4918 57.441 S4 even aspherical surface -40 / 1.4918 57.441 S5 even aspherical surface -40 9.1 1.5447 56.251 S6 even aspherical surface -32.1 3.759 / / S7 Binary2 Inf 2 1.5168 64.167 S8 flat Inf / / /

[0218] With respect to Table 4: S1 is the surface of the first lens 1 close to the human eye 01 (left surface), and S2 is the surface of the first lens 1 close to the display screen 4 (right surface);

[0219] S3 is the reflective polarization element 5, and S4 is the phase delay plate 6;

[0220] S5 is the surface of the second lens 2 close to the human eye 01 (left surface), and S6 is the surface of the second lens 2 close to the display screen 4 (right surface);

[0221] S7 is the surface of the diffractive optical element 7 close to the human eye 01 (left surface), and S8 is the surface of the diffractive optical element 3 close to the display screen 4 (right surface).

[0222] Table 5 shows the aspheric high-order coefficients.

[0223] Table 5

[0224] Serial number 4th 6th 8th 10th 12th 14th 16th S1 -4.35E-05 -2.31E-06 1.63E-08 -1.12E-11 -7.76E-14 -1.10E-15 4.15E-18 S2 -9.43E-05 1.00E-07 6.66E-11 -1.75E-12 -1.04E-14 7.81E-17 -1.14E-19 S5 -1.72E-05 -5.90E-09 -2.95E-11 1.09E-13 -5.91E-16 1.48E-18 -1.56E-21

[0225] Table 6 shows various coefficients of the microstructure surface of the diffractive optical element.

[0226] Table 6

[0227] Diffraction order Maximum number of terms <![CDATA[ρ 2 Item]]> <![CDATA[ρ 4 Item]]> <![CDATA[Ρ 6 Item]]> <![CDATA[Ρ 8 Item]]> 1 4 -1.07E+06 2.40E+07 -3.09E+08 1.04E+09

[0228] See also Figure 6 The vertical axis aberration curve of the optical system provided in Example 2 shows that the vertical axis aberration of the optical system is 23.9 μm, achieving a significant aberration correction effect.

[0229] Figure 7 for Figure 5 As shown in the modulation transfer function diagram of the optical system, the optical system provided by this embodiment 5 has an MTF average value greater than 0.3 at 57lp / mm.

[0230] Example 3

[0231] See also Figure 8 The optical system shown in this embodiment 3 includes a first lens 1, a reflective polarizing element 5, a phase retarder 6, a second lens 2, a beam splitter 7, a diffractive optical element 3 and a display screen 4, which are arranged in sequence along the same optical axis from the human eye side to the image source side;

[0232] The first lens 1 and the second lens 2 are even-order aspheric lenses, the first lens 1 and the second lens 2 are glued to each other and both are made of resin material;

[0233] The light splitting element 7 is arranged on a side surface of the second lens 2 close to the image source surface;

[0234] The phase retarder 6 and the reflective polarizing element 5 form a composite film and are arranged on the bonding surface of the first lens 1 and the second lens 2;

[0235] The diffractive optical element 3 is mainly composed of a substrate and a microstructure arranged on the substrate, and the microstructure can modulate the incident light so that the light is bent and dispersed during propagation, thereby correcting vertical axis chromatic aberration;

[0236] The display screen 4 emits light for imaging display, and the diffractive optical element 3 and the light-emitting surface of the display screen 4 are glued to each other.

[0237] The optical architecture of the optical system shown in this embodiment 3 is basically the same as the optical architecture of the optical system shown in the above-mentioned embodiment 1. Please refer to Tables 7 to 9 for the differences.

[0238] Table 7 shows the surface parameters of each element of the optical system of this embodiment 3.

[0239] Table 7

[0240] Serial number Surface type Curvature radius (mm) Thickness(mm) Refractive Index Abbe number S1 even aspherical surface -25.3 2.6 1.5447 56.251 S2 even aspherical surface -40.5 0.1 / / S3 even aspherical surface -40 0.1 1.4918 57.441 S4 even aspherical surface -40 / 1.4918 57.441 S5 even aspherical surface -40 9.1 1.5447 56.251 S6 even aspherical surface -31.4 3.949 / / S7 Binary2 Inf 2 1.5168 64.167 S8 flat Inf / / /

[0241] With respect to Table 7: S1 is the surface of the first lens 1 close to the human eye 01 (left surface), and S2 is the surface of the first lens 1 close to the display screen 4 (right surface);

[0242] S3 is the reflective polarization element 5, and S4 is the phase delay plate 6;

[0243] S5 is the surface of the second lens 2 close to the human eye 01 (left surface), and S6 is the surface of the second lens 2 close to the display screen 4 (right surface);

[0244] S7 is the surface of the diffractive optical element 7 close to the human eye 01 (left surface), and S8 is the surface of the diffractive optical element 3 close to the display screen 4 (right surface).

[0245] Table 8 shows the aspheric high-order coefficients.

[0246] Table 8

[0247] Serial number 4th 6th 8th 10th 12th 14th 16th S1 -2.51E-05 -2.31E-06 1.62E-08 -1.15E-11 -7.83E-14 -1.10E-15 4.18E-18 S2 -9.43E-05 1.00E-07 8.97E-11 -1.77E-12 -1.05E-14 7.81E-17 -1.14E-19 S5 -1.72E-05 -6.77E-09 -3.29E-11 1.08E-13 -5.83E-16 1.48E-18 -1.57E-21

[0248] Table 9 shows various coefficients of the microstructure surface of the diffractive optical element.

[0249] Table 9

[0250] Diffraction order Maximum number of terms <![CDATA[ρ 2 Item]]> <![CDATA[ρ 4 Item]]> <![CDATA[Ρ 6 Item]]> <![CDATA[Ρ 8 Item]]> 1 4 -1.04E+06 2.39E+07 -3.16E+08 1.09E+09

[0251] See also Fig. 9 The vertical axis aberration curve of the optical system provided in Example 3 shows that the vertical axis aberration of the optical system is 29.3 μm, achieving a significant aberration correction effect.

[0252] Fig.10 for Figure 8 As shown in the modulation transfer function diagram of the optical system, the optical system provided by this embodiment 5 has an MTF average value greater than 0.3 at 57lp / mm.

[0253] According to another embodiment of the present application, a smart head-mounted device is provided, wherein the smart head-mounted device includes a housing and the optical system as described above.

[0254] The smart head-mounted device provided in the embodiment of the present application is, for example, a VR optical display device.

[0255] The VR optical display device is in the form of, for example, VR smart glasses or VR smart helmets.

[0256] In the smart head-mounted device provided in an embodiment of the present application, two optical systems can be provided, one of which corresponds to the user's left eye and the other corresponds to the user's right eye.

[0257] The specific implementation of the intelligent head mounted device of the embodiment of the present application can refer to the various embodiments of the above-mentioned optical system, 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.

[0258] 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.

[0259] 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 only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments 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 system, characterized in that: It comprises an imaging component, a diffractive optical element (3) and a display screen (4) which are arranged in sequence along the same optical axis; The imaging component comprises a first lens (1), a reflective polarizing element (5), a phase retarder (6), a second lens (2) and a beam splitting element (7) which are arranged in sequence; The first lens (1) and the second lens (2) are both aspherical lenses; The diffractive optical element (3) and the display screen (4) are glued to each other; The diffractive optical element (3) is mainly composed of a substrate and a microstructure arranged on the substrate, wherein the microstructure is used to perform phase modulation on the light from the display screen (4) so ​​that the light is bent and dispersed during propagation; wherein the phase modulation effect of the microstructure on the light can generate a chromatic aberration effect opposite to the vertical axis chromatic aberration generated by the imaging component; When the light modulated by the microstructure enters the imaging component, the vertical axis chromatic aberration generated by the microstructure and the vertical axis chromatic aberration generated by the imaging component cancel each other out, thereby compensating for the vertical axis chromatic aberration of the imaging component and further correcting the vertical axis chromatic aberration of the optical system.

2. The optical system according to claim 1, characterized in that The surface of the microstructure is a binary surface, and the expression of the binary surface is: M = (A1ρ 2 +A2ρ 4 +A3ρ 6 +A4ρ 8 ), where M is the diffraction order, A1 is the quadratic phase coefficient used to correct chromatic aberration, A2, A3, A4 are aspheric phase coefficients, and ρ is the normalized polar coordinate radius.

3. The optical system according to claim 2, characterized in that The diffraction order is 1, -1.07E+06≤ρ 2 ≤-1.04E+06, 2.39E+07≤ρ 4 ≤2.41E+07,-3.16E+08≤ρ 6 ≤-3.09E+08,1.04E+09≤ρ 8 ≤1.09E+09.

4. The optical system according to claim 1, characterized in that The maximum thickness of the first lens (1) is T 1Max , the minimum thickness of the first lens (1) is T 1Mix , the first lens (1) satisfies: 0.14<(T 1Max -T 1Mix ) / T 1Max <1; The central thickness T2 of the second lens (2) is: T2>8mm.

5. The optical system according to claim 4, characterized in that The center thickness T1 of the first lens (1) and the center thickness T2 of the second lens (2) are respectively: 2mm≤T1≤10mm, 2mm≤T2≤10mm.

6. The optical system according to claim 1, characterized in that The curvature radius of the surface of the first lens (1) away from the display screen (4) is R1, and the curvature radius of the surface of the first lens (1) close to the display screen (4) is R2, and R1 and R2 satisfy: 55mm<|R1|+|R2|<80mm.

7. The optical system according to claim 6, characterized in that The curvature radius R1 of the surface of the first lens (1) away from the display screen (4) is -35mm<R1<-20mm, and the curvature radius R2 of the surface of the first lens (1) close to the display screen (4) is -45mm<R2<-35mm.

8. The optical system according to claim 6 or 7, characterized in that: The curvature radius R3 of the surface of the second lens (2) close to the display screen (4) is -40mm<R3<-30mm.

9. The optical system according to claim 1, characterized in that The optical system satisfies: 0.15<(|φ1|+|φ2|) / φ<0.2; wherein φ1 is the optical focal length of the first lens (1), φ2 is the optical focal length of the second lens (2), and φ is the total optical focal length of the optical system.

10. The optical system according to claim 1, characterized in that The straight-line distance between the first lens (1) and the exit pupil position of the optical system is d, 0<d<15mm; The exit pupil diameter of the optical system is D, 4mm<D<6mm.

11. The optical system according to claim 1, characterized in that The total length of the optical system is L, 30 mm < L < 40 mm, and the field of view FOV of the optical system is 140° < FOV < 160°.

12. The optical system according to claim 11, characterized in that The size of the display screen (4) is 60 mm to 75 mm.

13. The optical system according to claim 1, characterized in that The first lens (1) and the second lens (2) are glued together; The light splitting element (7) is arranged on a side surface of the second lens (2) close to the display screen (4); the phase delay plate (6) and the reflective polarizing element (5) form a composite film material and are arranged on the bonding surface of the first lens (1) and the second lens (2).

14. The optical system according to claim 1, characterized in that The first lens (1) and the second lens (2) are made of resin material; The first lens (1) and the second lens (2) are even-order aspheric lenses.

15. A smart head mounted device, characterized in that: include: shell; and An optical system as claimed in any one of claims 1 to 14.

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