Optical lens

Abstract

The invention provides an optical lens, and the optical lens sequentially comprises a first reflection element with positive focal power from an object side to an imaging surface, the first reflection element comprises an incident surface, a reflection surface and an emergent surface, the incident surface of the first reflection element is a convex surface, and the emergent surface of the first reflection element is a convex surface; included angles of 45 degrees are respectively formed between the reflecting surface of the first reflecting element and the optical axes of the incident surface and the emergent surface of the first reflecting element; the second lens has focal power; the third reflecting element has focal power and comprises an incident surface, a reflecting surface and an emergent surface; included angles of 45 degrees are respectively formed between the reflecting surface of the third reflecting element and the optical axes of the incident surface and the emergent surface of the third reflecting element; and the fourth lens has negative focal power. The optical lens provided by the invention adopts two reflecting elements with diopters as light path turning elements, so that a light path is turned twice to realize periscopic telephoto, and the optical lens has the characteristics of small volume, large aperture, large target surface and good performance.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging lenses, and particularly to an optical lens. Background Art

[0002] With the popularization and development of mobile intelligent devices, the functions and requirements of camera modules are constantly updated and improved. Among them, in order to capture distant objects more clearly, periscope telephoto lenses have received extensive attention due to their unique telephoto capabilities. However, such lenses usually require a longer and larger optical structure due to their longer focal lengths, occupying a relatively large volume in the entire camera module. Therefore, it is difficult to implement a periscope telephoto lens with a small volume, a large aperture, a large target surface, and a high-quality imaging effect in intelligent devices that pursue a thickness-to-width ratio. Summary of the Invention

[0003] Aiming at the above problems, the purpose of the present invention is to provide an optical lens with excellent imaging quality.

[0004] The technical solution adopted by the present invention is as follows: An optical lens is composed of two reflecting elements and two lenses, and successively includes from the object side to the imaging surface: A first reflecting element with a positive optical power, the first reflecting element includes an incident surface, a reflecting surface, and an exit surface, the incident surface of the first reflecting element is a convex surface, and the exit surface of the first reflecting element is a convex surface; the reflecting surface of the first reflecting element forms an angle of 45° with the optical axes of the incident surface and the exit surface of the first reflecting element respectively; A second lens with an optical power; A third reflecting element with an optical power, the third reflecting element includes an incident surface, a reflecting surface, and an exit surface; the reflecting surface of the third reflecting element forms an angle of 45° with the optical axes of the incident surface and the exit surface of the third reflecting element respectively; A fourth lens with a negative optical power; Wherein, the first reflecting element and the third reflecting element adopt an integrally formed structure; The optical axis of the optical lens includes a first optical axis and a second optical axis, the first optical axis is in the direction from the incident surface of the first reflecting element or the reflecting surface of the third reflecting element to the imaging surface, and the second optical axis is in the direction from the reflecting surface of the first reflecting element to the reflecting surface of the third reflecting element; The optical distance TL1 of the optical lens on the first optical axis satisfies: 12mm < TL1 < 15mm; the optical distance TL1 of the optical lens on the first optical axis and the sum TTL of the optical distances on the first optical axis and the second optical axis from the incident surface of the first reflecting element to the imaging surface satisfy: 0.52 < TL1 / TTL < 0.6.

[0005] More preferably, the incident surfaces and the exit surfaces of the first reflecting element and the third reflecting element are both aspherical surfaces, and the reflecting surfaces of the first reflecting element and the third reflecting element are both flat surfaces; the optical distance TL2 of the optical lens on the second optical axis and the sum TTL of the optical distances from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.4 < TL2 / TTL < 0.48.

[0006] More preferably, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.05 < BFL / f < 0.12; the back focal length BFL of the optical lens and the sum TTL of the optical distances from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.03 < BFL / TTL < 0.1.

[0007] More preferably, the effective focal length f of the optical lens and the focal length f1 of the first reflecting element satisfy: 0.3 < f1 / f < 1.

[0008] More preferably, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: -9 < f4 / f < -0.3.

[0009] More preferably, the effective focal length f of the optical lens and the combined focal length f123 of the first reflecting element, the second lens and the third reflecting element satisfy: 0.65 < f123 / f < 1.1.

[0010] More preferably, the combined focal length f123 of the first reflecting element, the second lens and the third reflecting element and the focal length f4 of the fourth lens satisfy: -2 < f123 / f4 < -0.1.

[0011] More preferably, the radius of curvature R1 of the incident surface of the first reflecting element and the effective focal length f of the optical lens satisfy: 0.5 < R1 / f < 0.8; the radius of curvature R2 of the exit surface of the first reflecting element and the effective focal length f of the optical lens satisfy: -1.2 < R2 / f < -0.2.

[0012] More preferably, the sum ΣCT of the propagation length of the light on the optical axis of the first reflecting element, the central thickness of the second lens, the propagation length of the light on the optical axis of the third reflecting element and the central thickness of the fourth lens and the sum TTL of the optical distances from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.8 < ΣCT / TTL < 0.9.

[0013] Further preferably, the effective aperture DM11 of the incident surface of the first reflecting element and the effective aperture DM42 of the image side surface of the fourth lens satisfy: 0.72 < DM11 / DM42 < 0.9.

[0014] Further preferably, the sum TTL of the optical distances from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis and the effective focal length f of the optical lens satisfy: 1.25 < TTL / f < 1.4; the sum TTL of the optical distances from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.9 < TTL / IH < 2.2.

[0015] Compared with the prior art, the optical lens of the present invention uses two reflecting elements with diopters as the optical path turning elements, so that the optical path turns twice to achieve periscope telephoto, and at the same time effectively reduces the number of lenses (only two additional lenses are needed to achieve high-performance imaging effects), greatly compresses the volume of the lens in the horizontal and vertical directions, and can effectively solve the requirements of small volume, large aperture, and large target surface for periscope telephoto lenses. Description of the Drawings

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and easy to understand from the description of the embodiments in conjunction with the following drawings, where: Figure 1 is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0017] Figure 2 is an axial aberration curve diagram of the optical lens in Embodiment 1 of the present invention.

[0018] Figure 3 is a longitudinal chromatic aberration curve diagram of the optical lens in Embodiment 1 of the present invention.

[0019] Figure 4 is a distortion curve diagram of the optical lens in Embodiment 1 of the present invention.

[0020] Figure 5 is a schematic structural diagram of the optical lens in Embodiment 2 of the present invention.

[0021] Figure 6 is an axial aberration curve diagram of the optical lens in Embodiment 2 of the present invention.

[0022] Figure 7 is a longitudinal chromatic aberration curve diagram of the optical lens in Embodiment 2 of the present invention.

[0023] Figure 8 is a distortion curve diagram of the optical lens in Embodiment 2 of the present invention.

[0024] Fig. 9 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0025] Fig.10 Graph showing the axial aberration of the optical lens in Embodiment 3 of the present invention.

[0026] Fig.11 Graph showing the magnification chromatic aberration of the optical lens in Example 3 of the present invention.

[0027] Fig.12 3 is a distortion curve diagram of the optical lens in Example 3 of the present invention.

[0028] Fig.13 Schematic diagram of the structure of the optical lens in Example 4 of the present invention.

[0029] Fig.14 4 is an axial aberration curve diagram of the optical lens in Example 4 of the present invention.

[0030] Fig.15 4 is a graph showing the magnification chromatic aberration of the optical lens in Example 4 of the present invention.

[0031] Fig.16 This is a distortion curve diagram of the optical lens in Example 4 of the present invention.

[0032] Fig.17 Schematic diagram of the structure of the optical lens in Example 5 of the present invention.

[0033] Fig.18 Graph showing the axial aberration of the optical lens in Embodiment 5 of the present invention.

[0034] Fig.19 Graph showing the magnification chromatic aberration of the optical lens in Embodiment 5 of the present invention.

[0035] Fig. 20 This is a distortion curve diagram of the optical lens in Example 5 of the present invention.

[0036] Fig.21 A schematic diagram of the light propagation path in an optical lens provided by an embodiment of the present invention.

[0037] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0038] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0039] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0040] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0041] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0042] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0043] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0044] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] The optical lens provided by the embodiment of the present invention is composed of two reflective elements and two lenses, and includes, from the object side to the imaging surface, a first reflective element, a second lens, a third reflective element, and a fourth lens. The present invention uses two reflective elements with refractive power as optical path turning elements, so that the optical path is turned twice to achieve periscope telephoto, while effectively reducing the number of lenses (only two additional lenses are added to achieve high-performance imaging effects), greatly compressing the volume of the lens in the horizontal and vertical directions, so that the optical lens has the characteristics of small volume, large aperture, large target surface, and strong performance.

[0046] Specifically, the first reflecting element may have a positive optical focal length, and the first reflecting element includes an incident surface, a reflecting surface and an exit surface. The incident surface of the first reflecting element is a convex surface, and the exit surface of the first reflecting element is a convex surface; the reflecting surface of the first reflecting element forms an angle of 45° with the optical axes of the incident surface and the exit surface of the first reflecting element respectively.

[0047] The second lens may have positive or negative refractive power, its object-side surface may be concave or convex, and its image-side surface may be concave or convex.

[0048] The third reflective element may have positive or negative optical power, and the third reflective element includes an incident surface, a reflecting surface, and an exiting surface. The incident surface of the third reflective element may be a concave surface or a convex surface, and the exiting surface of the third reflective element may be a concave surface or a convex surface. The reflecting surface of the third reflective element forms an angle of 45° with the optical axes of the incident surface and the exiting surface of the third reflective element, respectively.

[0049] The fourth lens element may have negative refractive power, and its object-side surface may be concave or convex, and its image-side surface may be concave or convex.

[0050] The first reflective element and the third reflective element both adopt an integrated structure, and can adopt a folding prism structure to bend the light, and can specifically be a right-angle triangular prism. The incident surface and the exit surface of the first reflective element and the third reflective element are both aspherical surfaces, and the reflective surfaces of the first reflective element and the third reflective element are both flat surfaces, which is conducive to reducing the weight and manufacturing cost of the prism, and provides advantages for achieving anti-shake of a larger prism.

[0051] In the embodiment of the present invention, the optical axis of the optical lens includes a first optical axis and a second optical axis, the first optical axis is along the direction from the incident surface of the first reflecting element or the reflecting surface of the third reflecting element to the imaging surface, the second optical axis is along the direction from the reflecting surface of the first reflecting element to the reflecting surface of the third reflecting element, and the first optical axis and the second optical axis are perpendicular to each other. Fig.21, The incident light enters the first reflecting element from the incident surface of the first reflecting element along the direction of the first optical axis, is reflected by the reflecting surface of the first reflecting element at a 90° turn, and then exits from the exit surface to the second lens, and then enters the third reflecting element from the incident surface of the third reflecting element, and is reflected by the reflecting surface of the third reflecting element at a 90° turn and exits from the exit surface to the fourth lens and then to the imaging surface. When the optical lens of the present invention is mounted on an imaging device, the first optical axis is parallel to the thickness direction of the imaging device, and the second optical axis is perpendicular to the thickness direction of the imaging device.

[0052] In some embodiments, the optical lens may further include a diaphragm, and the diaphragm may be located between the object side and the first reflecting element. It can be understood that the diaphragm is used to limit the amount of incident light to change the brightness of the image.

[0053] In some embodiments, the optical lens may further include a filter, and the filter may be disposed between the fourth lens and the imaging surface. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0054] In some embodiments, the optical distance TL1 of the optical lens on the first optical axis satisfies: 12mm < TL1 < 15mm; satisfying the above conditions can greatly reduce the size of the lens in the thickness direction of the imaging device. Specifically, the present application uses a double-reflecting lens to achieve two optical reflections, which can place the image sensor in the direction perpendicular to the thickness direction of the mobile phone in a periscope telephoto lens, effectively solving the problem that the traditional periscope lens cannot achieve a large target surface due to the thickness limitation of the device, and at the same time providing the possibility for implementing the optical image stabilization technology of the image sensor.

[0055] In some embodiments, the optical distance TL1 of the optical lens on the first optical axis and the sum TTL of the optical distances from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.52 < TL1 / TTL < 0.6. Satisfying the above conditions, by controlling the optical distance of the optical lens on the first optical axis, the thickness of the periscope lens on the imaging device it is mounted on can be greatly reduced, and the longitudinal thickness of the lens can be compressed to a great extent, which is beneficial to better mounting on a thin and light imaging device.

[0056] In some embodiments, the optical distance TL2 of the optical lens on the second optical axis and the sum TTL of the optical distances from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.4 < TL2 / TTL < 0.48. Satisfying the above conditions can make the optical lens have a smaller optical distance on the second optical axis, and it is significantly shorter than the periscope scheme with a single reflection, which has obvious advantages in compressing the thickness of the lens in the transverse direction and the volume of the module.

[0057] In some embodiments, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.05 < BFL / f < 0.12; the back focal length BFL of the optical lens and the total optical distance TTL from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.03 < BFL / TTL < 0.1. By satisfying the above conditions, by reasonably controlling the back focus of the lens, while ensuring the compatibility between the lens and the fuselage, the telephoto performance of the lens can be better realized, and the structure of the lens can be made more compact and the telephoto performance can be balanced.

[0058] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first reflecting element satisfy: 0.3 < f1 / f < 1. By satisfying the above conditions, the first reflecting element can have a large positive refractive power, which is beneficial to collecting light at large angles while realizing the perpendicular turning of the incident light, and at the same time reducing the height of the light incident on the first reflecting element and the thickness of the lens on the first optical axis, thereby better realizing the thinning of the lens.

[0059] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: -9 < f4 / f < -0.3. By satisfying the above conditions, the fourth lens can have a large negative refractive power, which is convenient for greatly diverging the incident light, making the peripheral light and the central light turn upwards to reach a higher imaging position, which is beneficial to realizing large-format imaging of the lens and improving the imaging quality.

[0060] In some embodiments, the effective focal length f of the optical lens and the combined focal length f123 of the first reflecting element, the second lens and the third reflecting element satisfy: 0.65 < f123 / f < 1.1. By satisfying the above conditions, on the one hand, it is beneficial to the convergence of light, enabling the light entering the reflecting element at the front end to smoothly enter the subsequent optical system, making the overall light path more gentle, and on the other hand, it is beneficial to optimizing aberrations and improving the overall resolution of the lens.

[0061] In some embodiments, the combined focal length f123 of the first reflecting element, the second lens and the third reflecting element and the focal length f4 of the fourth lens satisfy: -2 < f123 / f4 < -0.1. By satisfying the above conditions, it helps the object-side light beam to smoothly transition to the subsequent lens after two turns by the above reflecting elements, thereby ensuring high-quality imaging and low sensitivity of the optical lens.

[0062] In some embodiments, the radius of curvature R1 of the incident surface of the first reflecting element and the effective focal length f of the optical lens satisfy: 0.5 < R1 / f < 0.8; the radius of curvature R2 of the exit surface of the first reflecting element and the effective focal length f of the optical lens satisfy: -1.2 < R2 / f < -0.2. Meeting the above conditions, by reasonably controlling the radii of curvature of the incident surface and the exit surface of the first reflecting element, it helps the object-side light beam to smoothly transition to the subsequent lens after being refracted and converged by the first reflecting element, thus ensuring high-quality imaging and low sensitivity of the optical lens.

[0063] In some embodiments, the sum ΣCT of the propagation length of the light on the optical axis of the first reflecting element, the central thickness of the second lens, the propagation length of the light on the optical axis of the third reflecting element, and the central thickness of the fourth lens and the total optical distance TTL from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.8 < ΣCT / TTL < 0.9. Meeting the above conditions can effectively compress the total length of the optical lens and is conducive to the structural design and production process of the optical lens.

[0064] In some embodiments, the effective aperture DM11 of the incident surface of the first reflecting element and the effective aperture DM42 of the image side surface of the fourth lens satisfy: 0.72 < DM11 / DM42 < 0.9. Meeting the above conditions can make the lens have the characteristics of being thin, light, and having a large image surface, which is convenient for laying the lens group horizontally inside the mobile phone, conducive to improving the limitation problem brought by the external structure of the lens barrel, and thus improving the adaptability of the lens to the module motor.

[0065] In some embodiments, the total optical distance TTL from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis and the effective focal length f of the optical lens satisfy: 1.25 < TTL / f < 1.4; the total optical distance TTL from the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.9 < TTL / IH < 2.2. Meeting the above conditions ensures that the lens has a large image surface while having a small volume, can match a large-size imaging chip to achieve high-definition imaging, and better realizes the balance between the small total length and the large image surface of the lens.

[0066] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the optical lens and the effective focal length f of the optical lens satisfy: 0.6 < IH / f < 0.71. Meeting the above conditions can not only achieve the telephoto characteristics of the lens to meet the local shooting requirements, but also achieve the large image surface characteristics of the lens to better carry a large-size imaging chip and realize high-definition imaging of the lens.

[0067] In some embodiments, the optical distance TL1 of the optical lens on the first optical axis and the optical distance TL2 of the optical lens on the second optical axis satisfy: 1.1 < TL1 / TL2 < 1.5. Meeting the above conditions, by reasonably setting the distance relationship of the optical lens on the first and second optical axes, there are obvious advantages in reducing the size of the lens and the volume of the module. The lens can be much shorter in the second optical axis direction than the traditional periscope solution, better meeting the mounting requirements of thin and light electronic devices.

[0068] In some embodiments, the refractive index Nd1 of the first reflecting element satisfies: 1.5 < Nd1 < 1.6; the Abbe number Vd1 of the first reflecting element satisfies: 50 < Vd1 < 60. The refractive index Nd3 of the third reflecting element satisfies: 1.5 < Nd3 < 1.7; the Abbe number Vd3 of the third reflecting element satisfies: 18 < Vd3 < 60. Meeting the above conditions, by restricting the refractive index and Abbe number of the catadioptric lens, the two catadioptric lenses can be made of plastic material, and the integral molding of the product can be realized by injection molding process, which is beneficial to reducing the weight and manufacturing cost of the catadioptric lens, providing advantages for realizing large prism anti-shake. At the same time, by reasonably matching the refractive index and Abbe number of the catadioptric lens, it is beneficial to balance the purple wavelength aberration of the optical lens, helping to improve the purple fringing effect existing in the actual shooting effect of the periscope telephoto lens.

[0069] In some embodiments, the entrance pupil diameter EPD of the optical lens and the f-number Fno of the optical lens satisfy: 3.3 mm < EPD / Fno < 4.2 mm; the true image height IH corresponding to the maximum field of view angle of the optical lens and the f-number Fno of the optical lens satisfy: 5 mm < IH / Fno < 5.7 mm. Meeting the above conditions, by controlling the light passing aperture, f-number, and image height of the lens, while ensuring that the optical lens has a large image plane, it can have a larger light passing amount, which is beneficial to the realization of optical anti-shake technology in the periscope telephoto module and improves the imaging quality of the optical lens.

[0070] In some embodiments, the optical lens satisfies the following conditional expressions: 16 mm < f < 20 mm; 33° < FOV < 40°; 21.5 mm < TTL < 25.5 mm; 2.1 < Fno < 2.3; 11 mm < IH < 13 mm. In the above conditional expressions, f represents the effective focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, TTL represents the sum of the optical distances from the incident surface of the first reflecting element to the imaging surface on the first and second optical axes (i.e., the propagation path length of the light along the optical axis from the incident surface of the first reflecting element to the imaging surface), Fno represents the f-number of the optical lens, and IH represents the true image height corresponding to the maximum field of view angle of the optical lens. Meeting the above ranges, the optical lens has at least one or more advantages such as long focal length, miniaturization, large aperture, and large target surface.

[0071] In some embodiments, the lens material in the optical lens provided by the present invention may be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. When the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristic of the glass itself. The first reflective element, the second lens, the third reflective element, and the fourth lens provided by the present invention can be made of plastic material, which can make the structure of the lens more compact, can better achieve the balance between miniaturization of the lens and high image quality, and reduce costs.

[0072] In some embodiments, the second lens and the fourth lens may be spherical lenses or aspherical lenses. Compared with spherical structures, aspherical structures can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of lenses, and better realizing miniaturization of the lens. More specifically, the second lens and the fourth lens are both aspherical lenses.

[0073] In various embodiments of the present invention, when the lens and the reflective element are aspherical lenses, the shapes of the aspherical surfaces of the optical lens satisfy the following equations: ; Among them, z is the distance between the surface and the vertex of the surface in the direction of the optical axis, h is the distance from the optical axis to the surface, c is the curvature of the surface vertex, K is the quadratic surface coefficient, B, C, D, E, F, G, and H are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order surface coefficients respectively.

[0074] The present invention is further described below in multiple embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different. For specific differences, please refer to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any other changes, substitutions, combinations or simplifications that do not deviate from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0075] Example 1 See also Figure 1 , Figure 1 Schematic diagram of the structure of the optical lens 100 provided in Embodiment 1 of the present invention. The optical lens 100 includes, in order from the light propagation direction (from the object side to the imaging surface S11), an aperture ST, a first reflective element L1, a second lens L2, a third reflective element L3, a fourth lens L4 and a filter G1.

[0076] The first reflective element L1 has positive focal power, and includes an incident surface S1, a reflective surface R1, and an exit surface S2; the incident surface S1 is a convex surface, and the exit surface S2 is a convex surface; the incident surface S1 and the exit surface S2 are both aspherical surfaces, and the reflective surface R1 is a plane. The reflective surface R1 of the first reflective element L1 forms an angle of 45° with the optical axes of the incident surface S1 and the exit surface S2, respectively. It can be understood that the incident surface S1 faces the object side, and the exit surface S2 faces the second lens L2.

[0077] The second lens L2 has negative refractive power, its object-side surface S3 is concave, and its image-side surface S4 is concave; The third reflective element L3 has positive focal power, and includes an incident surface S5, a reflective surface R2, and an exit surface S6; the incident surface S5 is a convex surface, and the exit surface S6 is a concave surface; the incident surface S5 and the exit surface S6 are both aspherical surfaces, and the reflective surface R2 is a plane. The reflective surface R2 of the third reflective element L3 forms an angle of 45° with the optical axes of its incident surface S5 and the exit surface S6, respectively. It can be understood that its incident surface S5 faces the second lens L2, and its exit surface S6 faces the fourth lens L4.

[0078] The fourth lens L4 has negative refractive power, its object-side surface S7 is concave, and its image-side surface S8 is convex; The object side surface S9 and the image side surface S10 of the filter G1 are both planes; The imaging surface S11 is a plane.

[0079] The first reflective element L1 and the third reflective element L3 are integrally formed by injection molding and may adopt a folding-reflecting prism design, specifically a right-angle triangular prism.

[0080] The first reflective element L1 , the second lens L2 , the third reflective element L3 , and the fourth lens L4 are all plastic aspherical lenses.

[0081] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0082] Table 1-1 The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0083] Table 1-2 In this embodiment, the axial aberration curve, the magnification chromatic aberration curve, and the distortion curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 shown.

[0084] Figure 2The axial aberration curve of Example 1 is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ±0.05mm, indicating that the optical lens 100 can better correct the axial aberration.

[0085] Figure 3 The magnification chromatic aberration curve of Example 1 is shown, which represents the chromatic aberration of each wavelength relative to the central wavelength (550nm) at different image heights on the imaging surface, the horizontal axis represents the chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field angle. It can be seen from the figure that the chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±1μm, indicating that the optical lens 100 can correct chromatic aberration very well.

[0086] Figure 4 The distortion curve of Example 1 is shown, which represents the distortion of light of different wavelengths at different image heights on the imaging surface, with the horizontal axis representing the distortion value (unit: %) and the vertical axis representing the image height (unit: mm). It can be seen from the figure that the distortion of the optical lens is controlled within ±1%, indicating that the optical lens 100 can correct the distortion well.

[0087] Example 2 See also Figure 5 , shown is a schematic diagram of the structure of the optical lens 200 provided in Example 2 of the present invention. Compared with Example 1, the main differences of this embodiment are: the third reflective element L3 has negative optical focal length; the object side surface S3 of the second lens L2 is a convex surface; the incident surface S5 of the third reflective element L3 is a concave surface; the exit surface S6 of the third reflective element L3 is a convex surface; the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the lens material selection are different.

[0088] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0089] Table 2-1 The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0090] Table 2-2 In this embodiment, the axial aberration curve, the magnification chromatic aberration curve, and the distortion curve of the optical lens 200 are respectively as follows: Figure 6 , Figure 7 , Figure 8 shown.

[0091] from Figure 6It can be seen that the offset of the axial aberration is controlled within ±0.05 mm, indicating that the optical lens 200 can correct the axial aberration well.

[0092] from Figure 7 It can be seen that the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1 μm, indicating that the optical lens 200 can correct chromatic aberration very well.

[0093] from Figure 8 It can be seen that the distortion of the optical lens is controlled within ±0.5%, indicating that the optical lens 200 can correct the distortion well.

[0094] Example 3 See also Fig. 9 , shown is a schematic diagram of the structure of the optical lens 300 provided in Example 3 of the present invention. Compared with Example 1, the main differences of this embodiment are: the second lens L2 has positive optical power; the third reflective element L3 has negative optical power; the object side surface S3 of the second lens L2 is a convex surface; the image side surface S4 of the second lens L2 is a convex surface; the incident surface S5 of the third reflective element L3 is a concave surface; the exit surface S6 of the third reflective element L3 is a convex surface; the image side surface S8 of the fourth lens L4 is a concave surface; the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the lens material selection are different.

[0095] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0096] Table 3-1 The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0097] Table 3-2 In this embodiment, the axial aberration curve, the magnification chromatic aberration curve, and the distortion curve of the optical lens 300 are respectively as follows: Fig.10 , Fig.11 , Fig.12 shown.

[0098] from Fig.10 It can be seen that the offset of the axial aberration is controlled within ±0.05 mm, indicating that the optical lens 300 can correct the axial aberration well.

[0099] from Fig.11 It can be seen that the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1 μm, indicating that the optical lens 300 can correct chromatic aberration very well.

[0100] from Fig.12It can be seen that the distortion of the optical lens is controlled within ±1%, indicating that the optical lens 300 can correct the distortion well.

[0101] Example 4 See also Fig.13 , which is a schematic diagram of the structure of an optical lens 400 provided in Example 4 of the present invention. Compared with Example 1, this embodiment mainly differs in that: the object side surface S7 of the fourth lens L4 is a convex surface; the image side surface S8 of the fourth lens L4 is a concave surface; and the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the lens material selection are different.

[0102] The relevant parameters of each lens in the optical lens 400 in Example 4 are shown in Table 4-1.

[0103] Table 4-1 The surface parameters of the aspheric lens of the optical lens 400 in Example 4 are shown in Table 4-2.

[0104] Table 4-2 In this embodiment, the axial aberration curve, the magnification chromatic aberration curve, and the distortion curve of the optical lens 400 are respectively as follows: Fig.14 , Fig.15 , Fig.16 shown.

[0105] from Fig.14 It can be seen that the offset of the axial aberration is controlled within ±0.05 mm, indicating that the optical lens 400 can correct the axial aberration well.

[0106] from Fig.15 It can be seen that the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1 μm, indicating that the optical lens 400 can correct chromatic aberration very well.

[0107] from Fig.16 It can be seen that the distortion of the optical lens is controlled within ±1%, indicating that the optical lens 400 can correct the distortion well.

[0108] Example 5 See also Fig.17 , shown is a schematic diagram of the structure of the optical lens 500 provided in Example 5 of the present invention. Compared with Example 1, the main differences of this embodiment are: the image side surface S4 of the second lens L2 is a convex surface; the object side surface S5 of the third reflective element L3 is a concave surface; the image side surface S6 of the third reflective element L3 is a convex surface; the image side surface S8 of the fourth lens L4 is a concave surface; the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the lens material selection are different.

[0109] The relevant parameters of each lens in the optical lens 500 in Example 5 are shown in Table 5-1.

[0110] Table 5-1 The surface parameters of the aspheric lens of the optical lens 500 in Example 5 are shown in Table 5-2.

[0111] Table 5-2 In this embodiment, the axial aberration curve, the magnification chromatic aberration curve, and the distortion curve of the optical lens 500 are respectively as follows: Fig.18 , Fig.19 , Fig. 20 shown.

[0112] from Fig.18 It can be seen that the offset of the axial aberration is controlled within ±0.05 mm, indicating that the optical lens 500 can correct the axial aberration well.

[0113] from Fig.19 It can be seen that the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1.5 μm, indicating that the optical lens 500 can correct chromatic aberration very well.

[0114] from Fig. 20 It can be seen that the distortion of the optical lens is controlled within ±1%, indicating that the optical lens 500 can correct the distortion well.

[0115] Please refer to Table 6, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f of the optical lens, the sum of the optical distances TTL from the incident surface of the first reflective element to the imaging surface on the first optical axis and the second optical axis, the optical distance TL1 of the optical lens on the first optical axis, the optical distance TL2 of the optical lens on the second optical axis, the back focal length BFL of the optical lens, the aperture value Fno, the real image height IH corresponding to the maximum field of view angle of the optical lens, the maximum field of view angle FOV, and the numerical value corresponding to each conditional expression in each embodiment.

[0116] Table 6 Based on the above embodiments, the beneficial effects of the optical lens provided by the present invention are as follows: (1) Two refractive prisms with refractive power are used as optical path turning elements, so that the optical path is turned twice to achieve periscope telephoto, while effectively reducing the number of lenses (only two additional lenses are needed to achieve high-performance imaging effects). The size of the lens is greatly compressed in the horizontal and vertical directions, which can effectively solve the problem of small size, large aperture, and large target surface of periscope telephoto lenses.

[0117] (2) By properly matching the materials used for lenses and reflective elements, the periscope telephoto lens has the ability to correct the purple fringing effect, effectively suppressing the purple fringing aperture effect caused by purple light in actual telephoto shooting (see the aberration curve with a wavelength of 435nm in the performance curve diagram).

[0118] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0119] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An optical lens, characterized in that: It is composed of two reflecting elements and two lenses, and successively includes from the object side to the imaging surface: A first reflecting element with positive optical power, the first reflecting element includes an incident surface, a reflecting surface and an exit surface, the incident surface of the first reflecting element is convex, and the exit surface of the first reflecting element is convex; the reflecting surface of the first reflecting element forms an angle of 45° with the optical axes of the incident surface and the exit surface of the first reflecting element respectively; A second lens with optical power; A third reflecting element with optical power, the third reflecting element includes an incident surface, a reflecting surface and an exit surface; the reflecting surface of the third reflecting element forms an angle of 45° with the optical axes of the incident surface and the exit surface of the third reflecting element respectively; A fourth lens with negative optical power; Wherein, the first reflecting element and the third reflecting element adopt an integrally formed structure; The optical axis of the optical lens includes a first optical axis and a second optical axis, the first optical axis is in the direction from the incident surface of the first reflecting element or the reflecting surface of the third reflecting element to the imaging surface, and the second optical axis is in the direction from the reflecting surface of the first reflecting element to the reflecting surface of the third reflecting element; The optical distance TL1 of the optical lens on the first optical axis satisfies: 12mm < TL1 < 15mm; the optical distance TL1 of the optical lens on the first optical axis and the sum TTL of the optical distances of the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.52 < TL1 / TTL < 0.

6.

2. The optical lens according to claim 1, characterized in that: The incident surfaces and the exit surfaces of the first reflecting element and the third reflecting element are both aspherical surfaces, and the reflecting surfaces of the first reflecting element and the third reflecting element are both flat surfaces; the optical distance TL2 of the optical lens on the second optical axis and the sum TTL of the optical distances of the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.4 < TL2 / TTL < 0.

48.

3. The optical lens according to claim 1, characterized in that: The back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.05 < BFL / f < 0.12; the back focal length BFL of the optical lens and the sum TTL of the optical distances of the incident surface of the first reflecting element to the imaging surface on the first optical axis and the second optical axis satisfy: 0.03 < BFL / TTL < 0.

1.

4. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f1 of the first reflecting element satisfy: 0.3 < f1 / f < 1.

5. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: -9 < f4 / f < -0.

3.

6. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the combined focal length f123 of the first reflecting element, the second lens and the third reflecting element satisfy: 0.65 < f123 / f < 1.

1.

7. The optical lens according to claim 1, characterized in that: The combined focal length f123 of the first reflecting element, the second lens and the third reflecting element and the focal length f4 of the fourth lens satisfy: -2 < f123 / f4 < -0.

1.

8. The optical lens according to claim 1, characterized in that: The radius of curvature R1 of the incident surface of the first reflecting element and the effective focal length f of the optical lens satisfy: 0.5 < R1 / f < 0.8; the radius of curvature R2 of the exit surface of the first reflecting element and the effective focal length f of the optical lens satisfy: -1.2 < R2 / f < -0.

2.

9. The optical lens according to claim 1, characterized in that: The sum ΣCT of the propagation length of light on the optical axis of the first reflecting element, the central thickness of the second lens, the propagation length of light on the optical axis of the third reflecting element, and the central thickness of the fourth lens and the optical distance sum TTL between the incident surface of the first reflecting element and the imaging surface on the first optical axis and the second optical axis satisfy: 0.8 < ΣCT / TTL < 0.

9.

10. The optical lens according to claim 1, characterized in that: The effective aperture DM11 of the incident surface of the first reflecting element and the effective aperture DM42 of the image side surface of the fourth lens satisfy: 0.72 < DM11 / DM42 < 0.

9.

11. The optical lens according to claim 1, characterized in that: The optical distance sum TTL between the incident surface of the first reflecting element and the imaging surface on the first optical axis and the second optical axis and the effective focal length f of the optical lens satisfy: 1.25 < TTL / f < 1.4; the optical distance sum TTL between the incident surface of the first reflecting element and the imaging surface on the first optical axis and the second optical axis and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.9 < TTL / IH < 2.2.

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