Visible light lens and electronic equipment

Abstract

The invention relates to a visible light lens and electronic equipment, and belongs to the technical field of optical elements, the visible light lens is sequentially provided with a first lens, a second lens, a third lens and a fourth lens from an object plane to an image plane along an optical axis, the first lens, the third lens and the fourth lens are aspheric lenses, and the second lens is a metasurface lens. According to the invention, the total optical length is compressed by using the technical scheme of folding and super mixing, and the miniaturization and lightweight design is realized.

Description

Technical Field

[0001] The present invention belongs to the field of optical elements, and particularly relates to a visible light lens and an electronic device. Background Art

[0002] Visible light projection technology involves using the visible light band (about 400 - 700 nanometers) to project images, videos, or other content onto various surfaces, such as walls, screens, or other objects. Visible light projection is widely used in fields such as education, entertainment, commercial displays, advertising, and professional presentations, and has particularly seen rapid development in the AR / VR field in recent years.

[0003] Augmented reality (AR) and virtual reality (VR) are two rapidly developing technologies that have changed the way people interact with digital content and the real world. Augmented reality (AR): By superimposing digital information onto the view of the real world, it enhances the user's perception of the surrounding environment. For example, through a mobile phone camera or AR glasses, virtual objects, information, and animations can be seen in the real world. Virtual reality (VR): Creates a completely virtual environment for users to immerse themselves in. Users usually experience this virtual world through a head-mounted display (HMD) and sensing devices to interact with it.

[0004] In AR / VR devices, the visible light imaging lens plays a crucial role, and the size of the lens determines the compactness, light weight, and integration of the device.

[0005] However, for traditional visible light AR / VR projection lenses, multiple outer lenses are required to meet the imaging quality requirements, which results in a large number and complex assembly; moreover, traditional lenses are large in size and long in total optical length, making it impossible to achieve miniaturization, light weight, and integration. Summary of the Invention

[0006] This application provides a visible light lens and an electronic device to at least solve the above technical problems existing in the prior art.

[0007] In one aspect of the embodiments of this application, a visible light lens is provided. The visible light lens sequentially arranges a first lens, a second lens, a third lens, and a fourth lens along the optical axis from the object plane to the image plane. The first lens, the third lens, and the fourth lens are aspherical lenses, and the second lens is a metasurface lens.

[0008] In one implementable manner, the first lens is a lens with positive optical power, and its object side is convex; both the object side and the image side of the first lens are aspherical.

[0009] In one implementable manner, the distance from the optical axis center of the object side of the first lens to the image plane is TTL; wherein,

[0010] In an implementable embodiment, the second lens is a metasurface lens with positive optical power, its object side is a plane, and its image side has a microstructure arrangement; both the object side and the image side of the second lens are aspherical surfaces.

[0011] In an implementable embodiment, the third lens is a positive meniscus aspherical lens with positive optical power, and its object side is a convex surface.

[0012] In an implementable embodiment, the lens further includes a diaphragm, and the diaphragm is located on the side of the first lens close to the object surface;

[0013] Alternatively, the diaphragm is located between the first lens and the second lens;

[0014] Alternatively, the diaphragm is located between the second lens and the third lens.

[0015] In an implementable embodiment, the focal length f of the lens satisfies f≥5mm, the field of view angle FOV satisfies Fov≤30°, and the operating temperature is -30°C to 70°C.

[0016] In an implementable embodiment, the materials of the first lens, the third lens, and the fourth lens are resins.

[0017] In an implementable embodiment, the optical lens satisfies:

[0018]

[0019] where Y d is the maximum image height of the refractive - diffractive hybrid visible - light projection lens, Fno is the f - number, EFL is the focal length, and FOV is the diagonal field of view angle.

[0020] Another aspect of the embodiments of the present application provides an electronic device, including an image sensor and any one of the above - mentioned visible - light lenses, and the image sensor is disposed on the image plane of the visible - light lens.

[0021] Compared with the prior art, the present application has the following advantages:

[0022] 1. For traditional visible - light AR / VR projection lenses, multiple outer lenses are required to meet the imaging quality requirements, with a large number and complex assembly; while the present application adopts a refractive - diffractive hybrid technical solution, a four - element design, using three traditional resin - material lenses and one metasurface lens to achieve a large - aperture optical system.

[0023] 2. For traditional lenses, the thermal - aberration correction technology uses the thermal property differences of multiple materials to cooperate to achieve thermal - aberration correction, with a large number of materials used, a large number of lenses, relatively complex structures, and high costs. The temperature insensitivity of the metasurface lens can greatly reduce the design and processing difficulties; while the present application uses the negative - dispersion characteristic of the metasurface lens to achieve chromatic aberration correction and high - resolution imaging.

[0024] 3. Traditional lenses are large in size and long in overall optical length, making it impossible to achieve miniaturization, lightweight, and integration. However, the present application uses a refractive-diffractive hybrid technical solution to compress the overall optical length and achieve miniaturized and lightweight designs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of a visible light lens in an embodiment of the present application;

[0026] Figure 2 is an MTF schematic diagram of a visible light lens in an embodiment of the present application;

[0027] Figure 3 is a spot diagram of a visible light lens in an embodiment of the present application;

[0028] Figure 4 is a relative illumination schematic diagram of a visible light lens in an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0031] The present application discloses a visible light lens, Figure 1 is a schematic structural diagram of the visible light lens provided for the embodiment. In this embodiment, the visible light lens is set to satisfy The refractive-diffractive hybrid visible light projection lens has a relatively large focal length in the central region (the focal length can reach more than 5 mm), and can identify distant objects; and the overall field of view angle of the visible light lens is also relatively large (the field of view angle can reach more than 30°); where Y d is the maximum image height of the refractive-diffractive hybrid visible light projection lens, Fno is the f-number, EFL is the focal length, and FOV is the diagonal field of view angle.

[0032] In AR / VR devices, the visible light imaging lens plays a crucial role, and the size of the lens determines the compactness, lightweight, and integration of the device.

[0033] A metasurface is an artificial material with a thickness less than the wavelength, composed of a series of two-dimensional structural units at the micron scale. The manufacturing process of the metasurface is relatively simple, and conventional lithography, sputtering, spraying and other methods can be used, with low cost. By reasonably designing the metasurface, light field information can be collected to obtain an image of an object. Therefore, the lens prepared by using the metasurface technology is beneficial to miniaturize the device and save costs. The breakthrough of this technology will be widely applied in the fields of artificial intelligence, virtual reality, industrial manufacturing, etc.

[0034] This application uses a metasurface lens and a traditional lens to form a refractive-metamaterial hybrid system, which can well solve the problems existing in traditional lenses. The refractive-metamaterial hybrid lens can usually achieve a relatively high focal length and optical path folding, so as to realize the required optical path length within a relatively small optical system. This helps to reduce the volume and size of the optical system and make it more suitable for compact application scenarios.

[0035] As Figure 1 shown, along the optical axis from the object plane to the image plane of the visible light lens, a first lens 110, a second lens 120, a third lens 130 and a fourth lens 140 are sequentially arranged;

[0036] Among them, at least one of the first lens 110, the second lens 120, the third lens 130 and the fourth lens 140 is a metasurface lens. Since the metasurface lens has the function of achromatism, by setting at least one lens in the visible light lens as a metasurface lens, chromatic aberration can be effectively corrected, thereby improving the image quality of the visible light lens.

[0037] In this embodiment, the second lens 120 is a metasurface lens, and the first lens 110, the third lens 130 and the fourth lens 140 are aspherical lenses.

[0038] As a feasible implementation manner, the first lens 110 is an aspherical lens with positive optical power, its object side is a convex surface, and both its object side and image side are aspherical surfaces.

[0039] As a feasible implementation manner, the third lens 130 is an aspherical lens with positive optical power, and both its object side and image side are aspherical surfaces.

[0040] As a feasible implementation manner, the materials of the first lens 110, the second lens 130, and the third lens 140 are resin materials, and the material of the second lens 120 is silicon dioxide.

[0041] Among them, by setting the materials of the first lens 110, the third lens 120, and the fourth lens 140 to be resin and the material of the second lens 120 to be silica, the refractive - diffractive hybrid visible - light projection lens has an achromatic aberration function, so that the imaging quality of the visible - light projection lens remains unchanged within a certain range. At the same time, through the cooperation of materials and the optical powers of each lens, an athermal design is achieved, which not only reduces the material cost but also shrinks the volume of the system.

[0042] Reference Figure 1 , optionally, the visible - light projection provided by the embodiment of the present invention further includes a diaphragm 150. The diaphragm 150 is located on the side of the first lens 110 close to the object surface, or in the optical path between the first lens 110 and the second lens 120, or the diaphragm 150 is located in the optical path between the second lens 120 and the third lens 130.

[0043] As a feasible implementation manner, the diaphragm 150 is located in the optical path between the first lens 110 and the second lens 120.

[0044] Such as Figure 1 shown, the incident light enters through the object side surface of the first lens 110, passes through the diaphragm 140, and then passes through the second lens 120, the third lens 130, and the fourth lens 140 and finally converges on the imaging surface 160.

[0045] Exemplarily, Table 1 details the specific optical data parameters of each lens in the refractive - diffractive hybrid visible - light projection lens provided by the embodiment of the present invention in a feasible implementation manner. The optical data parameters in Table 1 correspond to Figure 1 the refractive - diffractive hybrid visible - light projection lens shown.

[0046] Among them, the first lens 110 is an aspherical lens with a positive optical power, and its object side surface is convex; both the object side surface and the image side surface of the first lens 110 are set as aspherical surfaces; the second lens 120 is a metasurface lens that can have a positive optical power, its object side surface is flat, and its image side surface is a micro - structured surface; the third lens 130 is a meniscus lens with a positive optical power, and its object side surface is convex; the diaphragm 150 is located between the first lens 110 and the second lens 120.

[0047] Table 1

[0048] Surface Number Surface Type Radius of Curvature (mm) Spacing (mm) Material Aperture (mm) 1 Standard Inf Infinity Infinity 2 Even Asphere 1.99 0.603 Resin 1.5 3 STOP Even Asphere 4.89 0.102 1.5 4 Standard inf 0.1 4 Standard inf 0.5 SI 1.6 5 Binary 2 inf 0.673 1.6 6 Even Asphere 1.71 0.576 Resin 1.1 7 Even Asphere 1.39 0.649 1.1 8 Even Asphere -6.58 0.965 Resin 0.8 9 Even Asphere -473.15 0.481 0.8 10 Standard Infinity - 1.7

[0049] Among them, the surface numbers are numbered according to the surface order of each lens. For example, surface number 1 represents the object side of the first lens 110, surface number 2 represents the image side of the first lens 110, and so on. Among them, the radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface bends towards the image side, and a negative value represents that the surface bends towards the object side. "Infinity" represents that the surface is a plane; the spacing represents the central axial distance from the current surface to the next surface. The units of both the radius of curvature and the spacing are millimeters (mm).

[0050] The even aspheric surface profile satisfies the following equation:

[0051]

[0052] Among them, z is the distance along the optical axis from the vertex of the even aspheric surface, r is the height from the optical axis, c is the curvature 1 / R, and R is the radius of curvature at the vertex of the lens; k is the conic coefficient -e2, and a2, a3, a4, a5, a6, a7, a8 are the high-order aspheric coefficients.

[0053] Exemplarily, Table 2 details the conic coefficient k and the high-order term coefficients a2, a3, a4, a5, a6, a7, a8 of the aspheric lens surface in this embodiment in a feasible implementation manner.

[0054] Table 2

[0055] Surface Number a2 a3 a4 a5 a6 a7 a8 3 -1.11E-02 -1.27E-02 2.81E-03 -2.37E-03 1.16E-05 5.04E-04 -3.71E-04 4 4.27E-02 -2.27E-02 -8.47E-03 8.70E-03 3.86E-06 -1.84E-03 3.62E-04 5 -5.22E-02 1.70E-03 -8.35E-02 2.51E-01 -3.40E-01 2.14E-01 -5.27E-02 6 -9.37E-02 2.26E-03 -2.01E-01 5.71E-01 -9.35E-01 6.77E-01 -2.12E-01 -1.74E-01 -1.30E-01 6.27E-02 -1.22E-01 -1.64E-01 1.81E-01 -1.83E-01 -7.65E-02 -5.23E-02 8.97E-03 1.20E-02 -8.14E-03 1.75E-03 1.81E-04

[0056] Among them, -4.12E-4 means that the coefficient a2 of surface number 3 is -4.12E-4, and so on.

[0057] Exemplarily, Table 3 details the phase of the metasurface in this embodiment in a feasible implementation manner.

[0058] Table 3

[0059] Surface Number R1 A1 A2 A3 A4 A5 6 1 -1.10E+02 -4.90E+01 1.98E+01 1.85E+01 -1.01E+01

[0060] Among them, R1 is the normalized radius of the binary surface.

[0061] In this embodiment, the focal length, the field of view angle, and the maximum image height satisfy The total length of the optical lens TTL and the focal length f satisfy

[0062] The working wavelength band of the visible light projection lens provided in this embodiment is 528nm ± 30nm, the F number is 1.3, the focal length is 5.8mm, and the maximum full field of view angle is 30°, meeting the usage requirements of AR glasses.

[0063] Figure 3 It is the MTF schematic diagram of the visible light projection lens provided by the embodiment of the present invention. In the embodiment of the present invention, the MTF of the central field of view is close to the diffraction limit at 100 lp / mm, and the MTF of the edge field of view is >0.25, enabling clear imaging.

[0064] Figure 3 It is the spot diagram of the visible light projection lens provided by the embodiment of the present invention. The refractive-diffractive visible light projection lens provided by the embodiment of the present invention has a relatively concentrated and uniform spot pattern in the entire long wavelength band, meeting the requirements of high-resolution imaging.

[0065] Figure 4 It is the relative illumination schematic diagram of the visible light projection lens provided by the embodiment of the present invention, which represents the relative illumination values corresponding to different fields of view. As Figure 4 shown, in the working wavelength band of the visible light projection lens provided by the embodiment of the present invention, the relative illumination within a 0.8 field of view is greater than 60%, and the brightness is uniform.

[0066] In summary, the visible light projection lens provided by the embodiment of the present invention has a large relative aperture, clear imaging, and a small TTL, meeting the requirements of high-resolution imaging and integrated lightweight.

[0067] The above is only the specific implementation manner of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily think of changes or substitutions, which should be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. A visible light lens, characterized in that: The visible light lens is provided with a first lens, a second lens, a third lens and a fourth lens in sequence along the optical axis from the object plane to the image plane, the first lens, the third lens and the fourth lens are aspherical lenses, and the second lens is a hypersurface lens.

2. The visible light lens according to claim 1, characterized in that: The first lens is a lens with positive refractive power, and the object side surface thereof is a convex surface; the object side surface and the image side surface of the first lens are both aspherical surfaces.

3. The visible light lens according to claim 2, characterized in that: The distance from the optical axis center of the object side of the first lens to the image plane is TTL; wherein, 4. The visible light lens according to claim 1, characterized in that: The second lens is a metasurface lens with positive optical power, the object side surface of which is a plane and the image side surface has a microstructure arrangement; the object side surface and the image side surface of the second lens are both aspherical surfaces.

5. The visible light lens according to claim 1, characterized in that: The third lens is a positive meniscus aspheric lens with positive optical power, and the object side surface of the third lens is a convex surface.

6. The visible light lens according to claim 1, characterized in that: The lens further comprises an aperture, and the aperture is located on a side of the first lens close to the object plane; Alternatively, the aperture is located between the first lens and the second lens; Alternatively, the aperture stop is located between the second lens and the third lens.

7. The visible light lens according to claim 1, characterized in that: The focal length f of the lens satisfies f≥5mm, the field of view FOV satisfies Fov≤30°, and the operating temperature is -30°C to 70°C.

8. The visible light lens according to claim 1, characterized in that: The first lens, the third lens and the fourth lens are made of resin.

9. The visible light lens according to claim 1, characterized in that: The optical lens meets the following requirements: Among them, Y d is the maximum image height of the refractive super hybrid visible light projection lens, Fno is the aperture number, EFL is the focal length, and FOV is the diagonal field of view.

10. An electronic device, characterized in that: The invention comprises an image sensor and a visible light lens according to any one of claims 1 to 9, wherein the image sensor is arranged on the image plane of the visible light lens.

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