Optical lens

Abstract

The invention provides an optical lens. The optical lens sequentially comprises a front lens group and a reflecting element with focal power from an object side to an imaging surface, the front lens group is composed of three lenses, and the three lenses sequentially comprise a first lens with positive focal power, a second lens with negative focal power and a third lens with focal power from the object side to the imaging surface; the object side surface of the first lens is a convex surface; the object side surface of the third lens is a concave surface; the reflecting element comprises an incident surface, a reflecting surface and an emergent surface, and the emergent surface of the reflecting element is a concave surface; an included angle of 45 degrees is formed between the reflecting surface of the reflecting element and the optical axis of the incident surface and the optical axis of the emergent surface of the reflecting element; wherein the reflecting element adopts an integrally formed structure, and the refractive index Nd4 of the reflecting element meets the following conditions: 1.5 lt; nd4lt; Nd4lt; and 1.7. According to the optical lens, the scheme that the lens group is placed in front of the reflecting element is adopted, light can be shrunk to a greater extent, the light inlet amount is greatly improved, and the aperture is increased.

Description

Technical Field

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

[0002] In order to obtain farther and higher quality shooting effects on mobile terminals, periscope telephoto lenses have gradually become the standard lenses for imaging modules in mobile devices based on their own telephoto advantages. However, the conventional traditional periscope solution that uses ordinary right-angle prisms and other refractive elements to bend the light path at the light inlet before entering the optical system has great deficiencies and disadvantages; for example: the lens appearance is square, which affects the appearance; the prism size is relatively large, the lens cost is high, and the module volume is large; due to the thickness of the equipment, that is, the prism size cannot be increased, and the amount of light entering the lens cannot be increased; therefore, the conventional periscope solution with ordinary prisms in front cannot meet the development needs of lenses with large aperture, large light flux, and high-quality imaging effects. Summary of the invention

[0003] In view of the above problems, an object of the present invention is to provide an optical lens having the advantage of excellent imaging quality.

[0004] The technical solution adopted by the present invention is: An optical lens, comprising, from the object side to the imaging surface, a front lens group and a reflective element with optical power; The front lens group is composed of three lenses, which include, from the object side to the imaging surface, a first lens with positive optical power, a second lens with negative optical power, and a third lens with optical power; Wherein, the object side surface of the first lens is a convex surface; the object side surface of the third lens is a concave surface; The reflective element comprises an incident surface, a reflective surface and an exit surface, and the exit surface of the reflective element is a concave surface; the reflective surface of the reflective element forms an angle of 45° with the optical axes of the incident surface and the exit surface of the reflective element; The reflective element adopts an integrated structure, and the refractive index Nd4 of the reflective element satisfies: 1.5 <Nd4<1.7。

[0005] Further preferably, the incident surface and the exit surface of the reflective element are both aspherical surfaces, and the reflective surface of the reflective element is a plane; the distance TL1 between the object side surface of the first lens and the reflective surface of the reflective element on the optical axis and the distance TL2 between the reflective surface of the reflective element and the imaging surface on the optical axis satisfy: 0.73 <TL1 / TL2<0.88。

[0006] More preferably, the distance TL1 on the optical axis between the object side surface of the first lens and the reflecting surface of the reflecting element and the effective focal length f of the optical lens satisfy: 0.5 < TL1 / f < 0.55; the distance TL2 on the optical axis between the reflecting surface of the reflecting element and the imaging surface and the effective focal length f of the optical lens satisfy: 0.6 < TL2 / f < 0.72.

[0007] More preferably, the focal length f4 of the reflecting element and the effective focal length f of the optical lens satisfy: -2.2 < f4 / f < 1.5.

[0008] More preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: 0.5 < f1 / f < 1.15.

[0009] More preferably, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -1.5 < f2 / f < -0.75.

[0010] More preferably, the effective focal length f of the optical lens and the combined focal length f123 of the front lens group satisfy: -2.5 < f123 / f < 3.3.

[0011] More preferably, the effective aperture CM11 of the object side surface of the first lens and the effective aperture CM42 of the exit surface of the reflecting element satisfy: 1.1 < CM11 / CM42 < 1.3; the maximum effective aperture DM1 of the first lens, the maximum effective aperture DM2 of the second lens, the maximum effective aperture DM3 of the third lens and the maximum effective aperture DM4 of the reflecting element satisfy: DM1 > DM2 > DM3 > DM4.

[0012] More preferably, the distance TTL on the optical axis from the object side surface of the first lens to the imaging surface and the back focal length BFL of the optical lens satisfy: 2.5 < TTL / BFL < 2.8; the distance TTL on the optical axis from the object side surface of the first lens to the imaging surface and the effective focal length f of the optical lens satisfy: 1.1 < TTL / f < 1.3.

[0013] More preferably, the curvature radius R1 of the object side surface of the first lens and the curvature radius R8 of the exit surface of the reflecting element satisfy: 0.05 < R1 / R8 < 0.7; the effective aperture CM41 of the incident surface of the reflecting element and the effective aperture CM42 of the exit surface of the reflecting element satisfy: 0.92 < CM41 / CM42 < 1.02.

[0014] More preferably, the refractive index temperature coefficient dn / dt of the reflecting element in the temperature range of 0 - 20 °C satisfies: 55×10 -6 / ℃ <dn / dt<75×10 -6 / ℃.

[0015] The optical lens of the present invention adopts a combination of three lens groups and a reflective element. The refractive power of the reflective element itself has a good balancing effect on the aberrations in the optical system, so that the lens has one or more advantages such as miniaturization, lightness, large aperture, high-quality imaging, and periscope telephoto. The solution of placing the lens group in front of the reflective element can shrink the light to a greater extent, greatly increase the amount of light entering and increase the aperture; after the light is compressed and enters the reflective element, the size of the reflective element can be reduced, thereby reducing the difficulty and cost of manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 Schematic diagram of the structure of the optical lens in Example 1 of the present invention.

[0017] Figure 2 Graph showing the axial aberration of the optical lens in Example 1 of the present invention.

[0018] Figure 3 Graph showing the magnification chromatic aberration of the optical lens in Example 1 of the present invention.

[0019] Figure 4 Schematic diagram of the structure of the optical lens in Example 2 of the present invention.

[0020] Figure 5 Graph showing the axial aberration of the optical lens in Embodiment 2 of the present invention.

[0021] Figure 6 Graph showing the magnification chromatic aberration of the optical lens in Example 2 of the present invention.

[0022] Figure 7 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0023] Figure 8 Graph showing the axial aberration of the optical lens in Embodiment 3 of the present invention.

[0024] Fig. 9 Graph showing the magnification chromatic aberration of the optical lens in Example 3 of the present invention.

[0025] Fig.10 Schematic diagram of the structure of the optical lens in Example 4 of the present invention.

[0026] Fig.11 4 is an axial aberration curve diagram of the optical lens in Example 4 of the present invention.

[0027] Fig.12 4 is a graph showing the magnification chromatic aberration of the optical lens in Example 4 of the present invention.

[0028] Fig.13 Schematic diagram of the structure of the optical lens in Example 5 of the present invention.

[0029] Fig.14 Graph showing the axial aberration of the optical lens in Embodiment 5 of the present invention.

[0030] Fig.15 Graph showing the magnification chromatic aberration of the optical lens in Embodiment 5 of the present invention.

[0031] Fig.16 Schematic diagram of the structure of the optical lens in Example 6 of the present invention.

[0032] Fig.17 Graph showing the axial aberration of the optical lens in Embodiment 6 of the present invention.

[0033] Fig.18 Graph showing the magnification chromatic aberration of the optical lens in Example 6 of the present invention.

[0034] Fig.19 Schematic diagram of the structure of the optical lens in Example 7 of the present invention.

[0035] Fig. 20 Graph showing the axial aberration of the optical lens in Embodiment 7 of the present invention.

[0036] Fig.21 Graph showing the magnification chromatic aberration of the optical lens in Example 7 of the present invention.

[0037] Fig. 22 A schematic diagram of the light propagation path in an optical lens provided by an embodiment of the present invention.

[0038] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The optical lens provided by the embodiment of the present invention includes, from the object side to the imaging surface, a front lens group and a reflective element with optical power. The reflective element of the present invention is used to deflect light, and by changing the angle of the light, the direction of the emitted light is perpendicular to the arrangement direction of the front lens group, thereby reducing the overall thickness of the optical system and achieving the effect of a periscope-type long focal length lens.

[0047] Specifically, the front lens group is composed of three lenses, which include, from the object side to the imaging surface: a first lens with positive optical power, a second lens with negative optical power, and a third lens with optical power, and the optical power of the third lens can be negative optical power or positive optical power. Among them, the object side surface of the first lens is convex, and the image side surface of the first lens is concave or convex. The object side surface of the second lens can be concave or convex, and the image side surface of the second lens can be concave or convex. The object side surface of the third lens is concave, and the image side surface of the third lens can be concave or convex.

[0048] The reflective element includes an incident surface, a reflective surface and an exit surface. The incident surface of the reflective element may be a concave surface or a convex surface, and the exit surface of the reflective element is a concave surface. Both the incident surface and the exit surface of the reflective element are aspherical surfaces, and the reflective surface of the reflective element is a plane. The reflective surface of the reflective element forms an angle of 45° with the optical axes of the incident surface and the exit surface of the reflective element. It can be understood that the incident light passes through the front lens group along the optical axis direction, enters the reflective element from the incident surface of the reflective element, and is reflected by the reflective surface and then exits from the exit surface to the imaging surface.

[0049] In some embodiments, the reflective element may adopt a prism structure for deflecting light. Specifically, it may be a right-angle triangular prism, and the reflective surface of the prism forms an angle of 45° with the optical axes of the incident surface and the exit surface of the prism. It is understandable that its incident surface faces the object side, and its exit surface faces the imaging surface. The direction of the light path can be changed by setting a folding prism, and the light path can be bent at 90°, so that the direction of the exiting light is perpendicular to the arrangement direction of the multiple lenses in the front lens group, reducing the overall thickness of the optical system; at the same time, the angle of the incident light can be converged, which is conducive to achieving the effect of periscope-type long focal length of the lens.

[0050] In the embodiment of the present invention, the lens group is placed in front of the reflective turning element, that is, the optical element at the lens light entrance is a conventional lens group, which can easily increase the aperture of the optical system while ensuring that all lenses in the image module of the device have a uniform circular appearance, and realize a periscope lens with a larger aperture. Therefore, the periscope lens solution with the lens group placed in front and the reflective element placed in the light path can effectively solve the problems of lens appearance, miniaturization, thinness, large aperture, and large aperture.

[0051] In some embodiments, the optical lens may further include an aperture, and the aperture may be located between the object side and the first lens. It is understood that the aperture is used to limit the amount of incoming light to change the brightness of the image.

[0052] In some embodiments, the optical lens may further include a filter, which may be disposed between the reflective element and the imaging surface. The filter is used to filter out interference light to prevent the interference light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0053] In some embodiments, the refractive index Nd4 of the reflective element satisfies: 1.5 < Nd4 < 1.7. Meeting the above conditions allows the reflective element to be made of plastic material and enables the integral molding of the reflective element using an injection molding process, which is beneficial for reducing the weight and manufacturing cost of the reflective element and provides advantages for achieving larger prism anti-shake.

[0054] In some embodiments, the refractive index temperature coefficient dn / dt of the reflective element within the temperature range of 0 - 20 °C satisfies: 55×10 -6 / °C < dn / dt < 75×10 -6 / °C. Meeting the above conditions, by reasonably selecting the plastic material of the reflective element and using a plastic reflective element with diopter at the back, the size of the turning element itself can be effectively reduced, and while reducing the manufacturing difficulty and cost, a higher-quality periscope telephoto shooting effect can be achieved with fewer optical lenses.

[0055] In some embodiments, the distance TL1 between the object side surface of the first lens and the reflective surface of the reflective element on the optical axis and the distance TL2 between the reflective surface of the reflective element and the imaging surface on the optical axis satisfy: 0.73 < TL1 / TL2 < 0.88. Meeting the above conditions, by reasonably setting the distance relationship between the optical lens on the first and second optical axes, it has obvious advantages in compressing the size of the lens and the volume of the module, and 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. It can be understood that in the present invention, the first optical axis (in the direction from the object side surface of the first lens to the reflective surface of the reflective element) and the second optical axis (in the direction from the reflective surface of the reflective element to the imaging surface) are perpendicular to each other; specifically, refer to Fig. 22 , in the figure, the incident light enters the front lens group along the first optical axis OX1, enters the reflective element from the incident surface of the reflective element, is refracted by 90° at the reflective surface and then exits from the exit surface along the second optical axis OX2 to the imaging surface, and the first optical axis OX1 and the second optical axis OX2 are perpendicular to each other. When the optical lens of the present invention is mounted on an imaging device, the first optical axis OX1 is parallel to the thickness direction of the imaging device, and the second optical axis OX2 is perpendicular to the thickness direction of the imaging device.

[0056] In some embodiments, the distance TL1 between the object side surface of the first lens and the reflective surface of the reflective element on the optical axis and the effective focal length f of the optical lens satisfy: 0.5 < TL1 / f < 0.55. Meeting the above conditions can effectively reduce the thickness of the lens group in the direction of the first optical axis (the thickness of the imaging device), which is beneficial for realizing the miniaturization and thinness of the lens and better meeting the mounting requirements of thin and light electronic devices.

[0057] In some embodiments, the distance TL2 between the reflecting surface of the reflecting element and the imaging surface on the optical axis and the effective focal length f of the optical lens satisfy: 0.6 < TL2 / f < 0.72. Meeting the above conditions, by reasonably controlling the propagation distance of light on the second optical axis, while ensuring the realization of the long focal length performance of the lens, the lens can be made much shorter than the traditional periscope scheme in the second optical axis direction, better meeting the mounting requirements of thin and light electronic devices.

[0058] In some embodiments, the focal length f4 of the reflecting element and the effective focal length f of the optical lens satisfy: -2.2 < f4 / f < 1.5. Meeting the above conditions, the reflecting element can turn the light to a large extent, better realizing the folding of the optical system. At the same time, the reflecting element has a large refractive power, which can realize the refraction of light and act as a lens, effectively improving the imaging quality of the lens. Therefore, by reasonably setting the optical power of the reflecting element, the size of the turning element itself can be effectively reduced, reducing the manufacturing difficulty and cost, and at the same time, a higher-quality periscope telephoto shooting effect can be achieved with fewer optical lenses.

[0059] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: 0.5 < f1 / f < 1.15. Meeting the above conditions, by setting the first lens to have a large positive refractive power, the incident light can be converged to a large extent, which is beneficial to realizing the long focal length characteristic of the lens and also beneficial to increasing the light input of the system and realizing a large aperture of the lens.

[0060] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -1.5 < f2 / f < -0.75. Meeting the above conditions, by setting the second lens to have a large negative refractive power, the incident light can be diverged to a large extent, thereby effectively increasing the height of the light entering the imaging surface and better realizing the large target surface imaging of the lens.

[0061] In some embodiments, the effective focal length f of the optical lens and the combined focal length f123 of the front lens group satisfy: -2.5 < f123 / f < 3.3. Meeting the above conditions, the front lens group can have a large refractive power, can contract the light to a large extent, greatly improve the light input and increase the aperture, and make the light enter the reflecting element with a smaller aperture more gently, better realizing the periscope telephoto performance and large aperture of the lens.

[0062] In some embodiments, the effective aperture CM11 of the object side surface of the first lens and the effective aperture CM42 of the exit surface of the reflective element satisfy: 1.1 < CM11 / CM42 < 1.3; the maximum effective aperture DM1 of the first lens, the maximum effective aperture DM2 of the second lens, the maximum effective aperture DM3 of the third lens, and the maximum effective aperture DM4 of the reflective element satisfy: DM1 > DM2 > DM3 > DM4. By satisfying the above conditions and reasonably setting the aperture relationships of the first and last lenses and elements, the lens can have a smaller head size while having a larger imaging surface, better meeting the balance of miniaturization and high pixels.

[0063] In some embodiments, the distance TTL from the object side surface of the first lens to the imaging surface on the optical axis and the back focal length BFL of the optical lens satisfy: 2.5 < TTL / BFL < 2.8; the distance TTL from the object side surface of the first lens to the imaging surface on the optical axis and the effective focal length f of the optical lens satisfy: 1.1 < TTL / f < 1.3. BFL represents the optical back focal length of the optical lens, that is, the shortest distance from the exit surface of the reflective element to the imaging surface. By satisfying the above conditions, it is beneficial to achieve the miniaturization of the lens. At the same time, the lens has a relatively large back focal length, reducing the interference during the assembly of the lens and the imaging chip and improving the assembly yield. It can be understood that the sum of the propagation paths of the light rays on the first optical axis and the second optical axis of the optical lens is the distance TTL from the object side surface of the first lens to the imaging surface on the optical axis.

[0064] In some embodiments, the curvature radius R1 of the object side surface of the first lens and the curvature radius R8 of the exit surface of the reflective element satisfy: 0.05 < R1 / R8 < 0.7. By satisfying the above conditions, it is beneficial to better converge the light rays, shorten the distance for the light rays to reach the imaging surface, and is beneficial to reducing the total length of the optical lens and achieving the miniaturization of the lens.

[0065] In some embodiments, the effective aperture CM41 of the incident surface of the reflective element and the effective aperture CM42 of the exit surface of the reflective element satisfy: 0.92 < CM41 / CM42 < 1.02. By satisfying the above conditions, by setting the incident surface and the exit surface of the reflective element to have relatively close apertures, it is beneficial to the processing of the reflective element while ensuring good light ray turning and achieving the periscope telephoto effect of the lens.

[0066] In some embodiments, the distance TL1 on the optical axis between the object side surface of the first lens and the reflecting surface of the reflecting element and the distance TTL on the optical axis from the object side surface of the first lens to the imaging surface satisfy: 0.4 < TL1 / TTL < 0.48; the distance TL2 on the optical axis between the reflecting surface of the reflecting element and the imaging surface and the distance TTL on the optical axis from the object side surface of the first lens to the imaging surface satisfy: 0.52 < TL2 / TTL < 0.6. Meeting the above conditions is conducive to the miniaturization and thinning of the lens while achieving the periscope telephoto shooting effect of the lens.

[0067] In some embodiments, the distance TTL on the optical axis from the object side surface of the first lens to the imaging surface and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.8 < TTL / IH < 2.2. Meeting the above conditions can better achieve the miniaturization of the lens, while ensuring that the lens has a large image plane and can match a large-size imaging chip to achieve high-definition imaging.

[0068] 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: 0.5 < IH / f < 0.7. Meeting the above conditions is conducive to realizing the telephoto characteristics of the lens and facilitating the realization of a large image plane of the lens, thereby improving the imaging quality of the optical lens.

[0069] In some embodiments, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: -3.5 < f2 / f3 < 3.5. Meeting the above conditions is conducive to the smooth transition of light and simultaneously corrects various aberrations of the optical lens, improving the imaging quality of the optical lens.

[0070] In some embodiments, the radius of curvature R8 of the exit surface of the reflecting element and the effective focal length f of the optical lens satisfy: 0.6 < R8 / f < 3.5. Meeting the above conditions, by reasonably setting the curvature of the exit surface of the reflecting element, the height of the light entering the imaging plane can be effectively increased, achieving large-image-plane imaging of the lens, while ensuring that the reflecting element is easy to process and improving the yield of injection molding.

[0071] In some embodiments, the maximum effective aperture DM1 of the first lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 0.75 < DM1 / IH < 0.9. Meeting the above conditions can make the lens have a smaller aperture and a larger image plane, and can better balance the miniaturization and high-quality imaging of the lens.

[0072] In some embodiments, the central thickness CT1 of the first lens and the central thickness CT2 of the second lens satisfy: 2.5 < CT1 / CT2 < 5.5. Meeting the above conditions is conducive to the processing and molding of the lens and improves the product yield.

[0073] In some embodiments, the optical lens satisfies the following conditional expressions: 12mm < f < 15mm; 30° < FOV < 37°; 14.5mm < TTL < 17.5mm; 1.9 < Fno < 2.1; 8.1mm < IH < 8.3mm. 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 distance from the object side of the first lens to the imaging plane on the optical axis (i.e., the length of the propagation path of light along the optical axis from the object side of the first lens to the imaging plane), Fno represents the aperture value 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 image plane.

[0074] In some embodiments, the lens material in the optical lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. On the other hand, 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 lens, second lens, third lens, and reflection element provided by the present invention can adopt plastic materials, which can make the structure of the lens relatively compact, and can better achieve the balance of lens miniaturization and high image quality, and reduce costs. Preferably, the refractive index of the materials of the first lens, second lens, third lens, and reflection element provided by the present invention is between 1.5 and 1.7. By reasonably matching the materials selected for the lens and the reflection element, the periscope telephoto lens can simultaneously have the ability to correct the purple fringing effect and effectively suppress the influence of the purple fringing aperture caused by purple light in actual telephoto shooting (see the aberration curve with a wavelength of 435nm in the performance curve graph).

[0075] In some embodiments, the reflection element adopts an aspherical prism, the reflection surface of the reflection element is a plane, the first lens, second lens, and third lens can adopt spherical lenses or aspherical lenses. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. More specifically, the incident surface and / or the exit surface of the reflection element of the present invention can be aspherical, and the first lens, second lens, and third lens all adopt aspherical lenses.

[0076] In various embodiments of the present invention, when the lens and the reflection element adopt aspherical lenses, the shapes of the aspherical surfaces of the optical lens satisfy the following equations: ; where z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the quadratic surface coefficient, and B, C, D, E, F, G, H are the surface coefficients of the fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order, and sixteenth order respectively.

[0077] 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.

[0078] 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), an aperture ST, a front lens group, a reflective element L4, and a filter G1; the front lens group has positive optical power and includes, in order from the object side to the imaging surface along the optical axis, a first lens L1, a second lens L2, and a third lens L3. It can be understood that the surface of each lens where the light enters is called the object side surface of the lens, and the surface where the light exits is called the image side surface of the lens.

[0079] The first lens L1 has positive refractive power, its object side surface S1 is convex, and its image side surface S2 is concave; The second lens L2 has negative refractive power, its object side surface S3 is concave, and its image side surface S4 is convex; The third lens L3 has positive refractive power, its object-side surface S5 is concave, and its image-side surface S6 is convex; The reflective element L4 has a negative optical focal length. The reflective element L4 adopts a folding prism design, which can be a right-angle triangular prism, including an incident surface S7, a reflective surface R0 and an exit surface S8; its incident surface S7 is a convex surface, and its exit surface S8 is a concave surface; its incident surface S7 and exit surface S8 are both aspherical surfaces, and the reflective surface R0 is a plane. The reflective surface R0 of the reflective element L4 forms an angle of 45° with the optical axes of its incident surface S7 and exit surface S8 respectively. It can be understood that its incident surface S7 faces the object side, and its exit surface S8 faces the imaging surface.

[0080] 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.

[0081] The first lens L1, the second lens L2, the third lens L3, and the reflective element L4 are all plastic aspheric lenses, and the reflective element L4 is an injection-molded integrated structure.

[0082] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0083] Table 1-1 The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0084] Table 1-2 In this embodiment, the axial aberration curve and the magnification chromatic aberration curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 shown.

[0085] Figure 2 The 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.

[0086] 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.

[0087] Example 2 See also Figure 4 , 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 reflective element L4 has positive focal length; 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 and the magnification chromatic aberration curve of the optical lens 200 are respectively as follows: Figure 5 , Figure 6 shown.

[0091] from Figure 5 It 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 6 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] Example 3 See also Figure 7 , 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 incident surface S7 of the reflective element 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.

[0094] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0095] Table 3-1 The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0096] Table 3-2 In this embodiment, the axial aberration curve and the magnification chromatic aberration curve of the optical lens 300 are respectively as follows: Figure 8 , Fig. 9 shown.

[0097] from Figure 8 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.

[0098] from Fig. 9 It can be seen that the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±2 μm, indicating that the optical lens 300 can correct chromatic aberration very well.

[0099] Example 4 See also Fig.10, shown is a schematic diagram of the structure of the optical lens 400 provided in Example 4 of the present invention. Compared with Example 1, the main differences of this embodiment are: the front lens group has negative optical focal length; the third lens L3 has negative optical focal length; the reflective element L4 has positive optical focal length; the image side surface S2 of the first lens L1 is a convex surface; 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 concave surface; the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the lens material selection are different.

[0100] The relevant parameters of each lens in the optical lens 400 in Example 4 are shown in Table 4-1.

[0101] Table 4-1 The surface parameters of the aspheric lens of the optical lens 400 in Example 4 are shown in Table 4-2.

[0102] Table 4-2 In this embodiment, the axial aberration curve and the magnification chromatic aberration curve of the optical lens 400 are respectively as follows: Fig.11 , Fig.12 shown.

[0103] from Fig.11 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.

[0104] from Fig.12 It can be seen that the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±2 μm, indicating that the optical lens 400 can correct chromatic aberration very well.

[0105] Example 5 See also Fig.13 , 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 front lens group has negative optical focal length; the third lens L3 has negative optical focal length; the reflective element L4 has positive optical focal length; the image side surface S6 of the third lens L3 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.

[0106] The relevant parameters of each lens in the optical lens 500 in Example 5 are shown in Table 5-1.

[0107] Table 5-1 The surface parameters of the aspheric lens of the optical lens 500 in Example 5 are shown in Table 5-2.

[0108] Table 5-2 In this embodiment, the axial aberration curve and the magnification chromatic aberration curve of the optical lens 500 are respectively as follows: Fig.14 , Fig.15 shown.

[0109] 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 500 can correct the axial aberration well.

[0110] from Fig.15 It can be seen that the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±2 μm, indicating that the optical lens 500 can correct chromatic aberration very well.

[0111] Example 6 See also Fig.16 , shown is a schematic diagram of the structure of the optical lens 600 provided in Example 6 of the present invention. Compared with Example 1, the main differences of this embodiment are: the front lens group has negative optical focal length; the third lens L3 has negative optical focal length; the reflective element L4 has positive optical focal length; the image side surface S2 of the first lens L1 is a convex surface; 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 concave surface; the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the lens material selection are different.

[0112] The relevant parameters of each lens in the optical lens 600 in Example 6 are shown in Table 6-1.

[0113] Table 6-1 The surface parameters of the aspheric lens of the optical lens 600 in Example 6 are shown in Table 6-2.

[0114] Table 6-2 In this embodiment, the axial aberration curve and the magnification chromatic aberration curve of the optical lens 600 are respectively as follows: Fig.17 , Fig.18 shown.

[0115] from Fig.17 It can be seen that the offset of the axial aberration is controlled within ±0.05 mm, indicating that the optical lens 600 can correct the axial aberration well.

[0116] from Fig.18 It can be seen that the chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±2μm, indicating that the optical lens 600 can correct chromatic aberration very well.

[0117] Example 7 See also Fig.19 , shown is a schematic diagram of the structure of the optical lens 700 provided in Example 7 of the present invention. Compared with Example 1, the main differences of this embodiment are: the front lens group has negative optical focal length; the third lens L3 has negative optical focal length; the reflective element L4 has positive optical focal length; the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the lens material selection are different.

[0118] The relevant parameters of each lens in the optical lens 700 in Example 7 are shown in Table 7-1.

[0119] Table 7-1 The surface parameters of the aspheric lens of the optical lens 700 in Example 7 are shown in Table 7-2.

[0120] Table 7-2 In this embodiment, the axial aberration curve and the magnification chromatic aberration curve of the optical lens 700 are respectively as follows: Fig. 20 , Fig.21 shown.

[0121] from Fig. 20 It can be seen that the offset of the axial aberration is controlled within ±0.05 mm, indicating that the optical lens 700 can correct the axial aberration well.

[0122] from Fig.21 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 700 can correct chromatic aberration very well.

[0123] Please refer to Table 8, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f of the optical lens, the distance TTL from the object side of the first lens to the imaging surface on the optical axis, TL1 represents the distance between the object side of the first lens and the reflecting surface of the reflecting element on the optical axis, TL2 represents the distance between the reflecting surface of the reflecting element and the imaging surface on the optical axis, BFL represents the back focal length of the optical lens, that is, the shortest distance from the exit surface of the reflecting element to the imaging surface, 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.

[0124] Table 8 Based on the above embodiments, the beneficial effects of the optical lens provided by the present invention are as follows: (1) The optical lens of the present invention has one or more advantages such as miniaturization, lightness, large aperture, high-quality imaging, and periscope telephoto.

[0125] (2) Placing the lens group in front of the reflective element can shrink the light to a greater extent, greatly increase the amount of light entering and increase the aperture; after the light is compressed, it enters the reflective element, which can reduce the size of the reflective element, thereby reducing the manufacturing difficulty and cost.

[0126] (3) Compared with the conventional prism-front periscope solution in the prior art, the reflective element in the present invention is rear-positioned, which can make the reflective element (prism) of the optical lens smaller, and the manufacturing difficulty and cost will be lower, because the front lens group compresses the light.

[0127] (4) 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).

[0128] 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.

[0129] 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: From the object side to the imaging surface, it sequentially includes: a front lens group and a reflective element with a focal power. The front lens group consists of three lenses, and sequentially includes from the object side to the imaging surface: a first lens with a positive focal power, a second lens with a negative focal power, and a third lens with a focal power. Among them, the object side surface of the first lens is convex; the object side surface of the third lens is concave. The reflective element includes an incident surface, a reflective surface, and an exit surface. The exit surface of the reflective element is concave; the reflective surface of the reflective element forms a 45° angle with the optical axes of the incident surface and the exit surface of the reflective element. Among them, the reflective element adopts an integrally formed structure, and the refractive index Nd4 of the reflective element satisfies: 1.5 < Nd4 < 1.

7.

2. The optical lens according to claim 1, characterized in that: Both the incident surface and the exit surface of the reflective element are aspherical surfaces, and the reflective surface of the reflective element is a plane; the distance TL1 on the optical axis between the object side surface of the first lens and the reflective surface of the reflective element and the distance TL2 on the optical axis between the reflective surface of the reflective element and the imaging surface satisfy: 0.73 < TL1 / TL2 < 0.

88.

3. The optical lens according to claim 1, characterized in that: The distance TL1 on the optical axis between the object side surface of the first lens and the reflective surface of the reflective element and the effective focal length f of the optical lens satisfy: 0.5 < TL1 / f < 0.55; the distance TL2 on the optical axis between the reflective surface of the reflective element and the imaging surface and the effective focal length f of the optical lens satisfy: 0.6 < TL2 / f < 0.

72.

4. The optical lens according to claim 1, characterized in that: The focal length f4 of the reflective element and the effective focal length f of the optical lens satisfy: -2.2 < f4 / f < 1.

5.

5. 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 lens satisfy: 0.5 < f1 / f < 1.

15.

6. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -1.5 < f2 / f < -0.

75.

7. 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 front lens group satisfy: -2.5 < f123 / f < 3.

3.

8. The optical lens according to claim 1, characterized in that: The effective aperture CM11 of the object side surface of the first lens and the effective aperture CM42 of the exit surface of the reflective element satisfy: 1.1 < CM11 / CM42 < 1.3; the maximum effective aperture DM1 of the first lens, the maximum effective aperture DM2 of the second lens, the maximum effective aperture DM3 of the third lens, and the maximum effective aperture DM4 of the reflective element satisfy: DM1 > DM2 > DM3 > DM4.

9. The optical lens according to claim 1, characterized in that: The distance TTL on the optical axis from the object side surface of the first lens to the imaging surface and the back focal length BFL of the optical lens satisfy: 2.5 < TTL / BFL < 2.8; the distance TTL on the optical axis from the object side surface of the first lens to the imaging surface and the effective focal length f of the optical lens satisfy: 1.1 < TTL / f < 1.

3.

10. The optical lens according to claim 1, characterized in that: The radius of curvature R1 of the object side surface of the first lens and the radius of curvature R8 of the exit surface of the reflecting element satisfy: 0.05 < R1 / R8 < 0.7; the effective aperture CM41 of the incident surface of the reflecting element and the effective aperture CM42 of the exit surface of the reflecting element satisfy: 0.92 < CM41 / CM42 < 1.

02.

11. The optical lens according to claim 1, characterized in that: The refractive index temperature coefficient dn / dt of the reflective element in the temperature range of 0-20°C satisfies: 55×10 -6 / ℃ <dn / dt<75×10 -6 / ℃.

Images