Telephoto lens

Abstract

The utility model discloses a telephoto lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from an object plane to an image plane along an optical axis, and the focal power of each lens meets the condition that phi 1 / phi is more than or equal to 0.35 and less than or equal to 0.67; phi 2 / phi is greater than or equal to-0.85 and less than or equal to-0.53; 1.14 < = phi 3 / phi < = 2.12; -1.83 < = [phi] 4 / [phi] < = 2.49; -1.03 < = phi 5 / phi < =-0.56; 1.06 < = phi 6 / phi < = 1.50. According to the telephoto lens provided by the embodiment of the utility model, only six lenses are used, the focal length of the telephoto lens can reach about 12mm, the aperture number F is less than or equal to 1.6, the total length TTL is less than or equal to 22mm through reasonably distributing the focal power of each lens, the telephoto lens has good imaging performance, and the telephoto lens is large in aperture, small in size and low in cost.

Description

Technical Field

[0001] The utility model relates to the technical field of optics, in particular to a telephoto lens. Background Art

[0002] In the security market, with the increasingly fierce competition, the performance requirements for lenses are getting higher and higher. Most of the lenses currently used in security systems have short focal lengths, making it difficult to achieve long-distance monitoring; and they have small apertures, large volumes, high costs, and are easily restricted by the installation space. Content of the Utility Model

[0003] The utility model provides a telephoto lens to achieve a telephoto lens with a large aperture, small volume and low cost.

[0004] The utility model provides a telephoto lens, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence from the object surface to the image surface along the optical axis;

[0005] The first lens has a positive optical power, the second lens has a negative optical power, the third lens has an optical power, the fourth lens has an optical power, the fifth lens has a negative optical power, and the sixth lens has a positive optical power;

[0006] The optical power of the telephoto lens is The optical power of the first lens is The optical power of the second lens is The optical power of the third lens is The optical power of the fourth lens is The optical power of the fifth lens is The optical power of the sixth lens is

[0007]

[0008]

[0009]

[0010] Optionally, the third lens has a negative optical power, and the fourth lens has a positive optical power.

[0011] Optionally, the third lens has a positive optical power, and the fourth lens has a negative optical power.

[0012] Optionally, the object side surface of the first lens is convex;

[0013] The object side surface of the second lens is convex, and the image side surface of the second lens is concave;

[0014] The object side of the third lens is convex;

[0015] The image side of the fourth lens is convex;

[0016] The object side of the fifth lens is concave, and the image side of the fifth lens is convex;

[0017] The object side of the sixth lens is convex, and the image side of the sixth lens is concave.

[0018] Optionally, the refractive index of the third lens is Nd3, and the Abbe number is Vd3; the refractive index of the fourth lens is Nd4, and the Abbe number is Vd4;

[0019] 1.47 ≤ Nd3 ≤ 1.84; 1.43 ≤ Nd4 ≤ 1.90;

[0020] 15.22 ≤ Vd3 ≤ 83.30; 23.21 ≤ Vd4 ≤ 95.00.

[0021] Optionally, the third lens and the fourth lens form a cemented lens group.

[0022] Optionally, the distance between the third lens and the fourth lens on the optical axis is greater than 0.

[0023] Optionally, the first lens, the third lens, and the fourth lens are all glass spherical lenses;

[0024] The second lens, the fifth lens, and the sixth lens are all plastic aspherical lenses.

[0025] Optionally, the telephoto lens further includes a diaphragm;

[0026] The diaphragm is located in the optical path between the first lens and the second lens.

[0027] Optionally, the total length of the telephoto lens is TTL, and TTL ≤ 22 mm.

[0028] The telephoto lens provided by the embodiment of the present invention only uses 6 lenses. By reasonably distributing the optical power of each lens, the focal length of the telephoto lens can reach about 12 mm, the aperture number F ≤ 1.6, the total length TTL ≤ 22 mm, and it has good imaging performance, thus realizing a telephoto lens with a large aperture, a small volume, and low cost.

[0029] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0030] To more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 Structural schematic diagram of a telephoto lens provided by an embodiment of the present utility model;

[0032] Figure 2 Structural schematic diagram of another telephoto lens provided by an embodiment of the present utility model;

[0033] Figure 3 Structural schematic diagram of yet another telephoto lens provided by an embodiment of the present utility model;

[0034] Figure 4 Spherical aberration curve graph of the telephoto lens provided by Embodiment 1 of the present utility model;

[0035] Figure 5 Spherical aberration curve graph of the telephoto lens provided by Embodiment 2 of the present utility model;

[0036] Figure 6 Spherical aberration curve graph of the telephoto lens provided by Embodiment 3 of the present utility model. Specific embodiments

[0037] In order to enable those skilled in the art to better understand the solutions of the present utility model, the following will clearly and completely describe the technical solutions in the embodiments of the present utility model in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only some, rather than all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0038] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present utility model are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present utility model described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily limit to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0039] Figure 1 The structural schematic diagram of a telephoto lens provided by an embodiment of the present utility model Figure 2 The structural schematic diagram of another telephoto lens provided by an embodiment of the present utility model Figure 3 The structural schematic diagram of still another telephoto lens provided by an embodiment of the present utility model. As Figures 1-3 shown, the telephoto lens provided by the embodiment of the present utility model includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and a sixth lens L6 arranged in sequence from the object plane to the image plane along the optical axis. The first lens L1 has a positive optical power, the second lens L2 has a negative optical power, the third lens L3 has an optical power, the fourth lens L4 has an optical power, the fifth lens L5 has a negative optical power, and the sixth lens L6 has a positive optical power. The optical power of the telephoto lens is The optical power of the first lens L1 is The optical power of the second lens L2 is The optical power of the third lens L3 is The optical power of the fourth lens L4 is The optical power of the fifth lens L5 is The optical power of the sixth lens L6 is Wherein:

[0040]

[0041]

[0042]

[0043] Specifically, the optical power is equal to the difference between the convergence of the image-space light beam and the convergence of the object-space light beam, and it characterizes the ability of an optical system to deflect light rays. The greater the absolute value of the optical power, the stronger the bending ability of the light rays; the smaller the absolute value of the optical power, the weaker the bending ability of the light rays. When the optical power is positive, the refraction of the light rays is convergent; when the optical power is negative, the refraction of the light rays is divergent. The optical power can be used to characterize a certain refracting surface of a lens (i.e., one surface of the lens), can be used to characterize a certain lens, or can be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0044] In the telephoto lens provided in this embodiment, each lens can be fixed in a lens barrel ( Figure 1 not shown in the figure), but it is not limited to this.

[0045] Among them, the first lens L1 has a positive optical power and can play a role in gathering light rays, thereby controlling the angle of the light rays entering the subsequent lenses, which is beneficial to reducing the influence of aberration.

[0046] The second lens L2 has a negative optical power and can help correct the aberration caused by the first lens L1.

[0047] Among them, setting the optical power of the first lens L1 and the optical power of the second lens L2 to satisfy the conditional formula while effectively controlling the incident angle of the light rays entering the subsequent lenses, helps to correct the field curvature. In the case of a long focal length, a relatively flat image plane and a clear image can also be obtained, thereby improving the imaging quality of the telephoto lens.

[0048] The third lens L3 can have a positive optical power or a negative optical power; the fourth lens L4 can have a positive optical power or a negative optical power.

[0049] Among them, setting the optical power of the third lens L3 and the optical power of the fourth lens L4 to satisfy the conditional formula can effectively contract the light rays and help the light rays to better converge on the image plane. At the same time, through reasonable optical power distribution, it helps to reduce the dependence on the accuracy of a single lens, reduce the error accumulation during the assembly process, thereby reducing the negative impact caused by assembly tolerances and improving the production yield.

[0050] The fifth lens L5 has a negative optical power and is used to diverge the light rays, which helps to correct the off-axis aberration.

[0051] The sixth lens L6 has a positive optical power and is used to focus the light rays, which helps to optimize the principal ray angle and reduce distortion.

[0052] Among them, the optical power of the fifth lens L5 is set and the optical power of the sixth lens L6 satisfy the conditional formula which can correct off-axis aberration, optimize the chief ray angle, reduce distortion, and can also optimize the back focal distance, reduce the total length of the telephoto lens, and is beneficial to realizing a miniaturized lens design.

[0053] The telephoto lens provided by the embodiment of the present utility model only uses 6 lenses. By reasonably distributing the optical powers of each lens, the focal length of the telephoto lens can reach about 12 mm, the aperture number F ≤ 1.6, and the total length TTL ≤ 22 mm, and it has good imaging performance, thus realizing a telephoto lens with a large aperture, a small volume, and a low cost.

[0054] As Figure 1 and Figure 3 shown, as a feasible implementation manner, the third lens L3 has a negative optical power, and the fourth lens L4 has a positive optical power.

[0055] Among them, the third lens L3 is set to have a negative optical power for diverging light rays, which helps to compensate for the aberration caused by the front first lens L1. At the same time, it can also help reduce the burden on the subsequent lenses, making it easier for the entire lens to achieve the required optical performance.

[0056] The fourth lens L4 has a positive optical power, which can effectively converge the light rays and help the light rays to better converge on the image plane.

[0057] It should be noted that continuously using lenses with strong positive or strong negative optical powers may cause the light rays to be severely deflected at a certain point, which will not only increase the aberration but also may cause energy loss in the optical path.

[0058] In this embodiment, the third lens L3 has a negative optical power and the fourth lens L4 has a positive optical power, which can make the propagation process of the light rays in the telephoto lens more stable, and the light rays will not have too large a deflection on a certain surface, thereby avoiding introducing larger aberrations. At the same time, it can also make the distribution of the optical powers between the lenses more uniform, which helps to reduce the dependence on the accuracy of a single lens, reduce the error accumulation during the assembly process, thereby reducing the negative impact caused by the assembly tolerance, improving the production yield, and reducing the production cost.

[0059] In addition, the third lens L3 has a negative optical power, the fourth lens L4 has a positive optical power, and is combined with the fifth lens L5 having a negative optical power and the sixth lens L6 having a positive optical power, so as to adopt a negative-positive-negative-positive optical power combination, which is beneficial to reducing the total length of the entire telephoto lens while making the propagation process of the light rays in the telephoto lens more stable, thereby realizing a miniaturized lens design.

[0060] As Figure 2As shown, as a feasible implementation, the third lens L3 has positive refractive power, and the fourth lens L4 has negative refractive power.

[0061] Among them, setting the third lens L3 to adopt positive optical focal length can effectively shrink light and help improve image clarity and contrast.

[0062] The fourth lens L4 adopts negative optical power, which helps to correct off-axis aberrations. At the same time, it can also help reduce the burden on subsequent lenses, making it easier for the entire telephoto lens to achieve the required optical performance indicators.

[0063] It should be noted that the continuous use of lenses with strong positive or negative power may cause drastic deflection of light at a certain point, which will not only increase aberrations but also cause energy loss in the optical path.

[0064] In this embodiment, the third lens L3 adopts positive focal power, and the fourth lens L4 adopts negative focal power, which can make the propagation process of light in the telephoto lens more stable, and the light will not be deflected too much on a certain surface, thereby avoiding the introduction of larger aberrations. At the same time, it can also make the focal power distribution between lenses more uniform, help reduce the dependence on the accuracy of a single lens, reduce the error accumulation in the assembly process, thereby reducing the negative impact caused by assembly tolerance, improving production yield, and reducing production costs.

[0065] Continue to refer Figures 1-3 As a feasible implementation, the object side surface of the first lens L1 is convex. The object side surface of the second lens L2 is convex, and the image side surface of the second lens L2 is concave. The object side surface of the third lens L3 is convex. The image side surface of the fourth lens L4 is convex. The object side surface of the fifth lens L5 is concave, and the image side surface of the fifth lens L5 is convex. The object side surface of the sixth lens L6 is convex, and the image side surface of the sixth lens L6 is concave.

[0066] Among them, the surface shape of the lens affects the propagation direction of light and determines how the light bends when passing through the lens, which in turn affects the maximum aperture and light transmittance of the lens, as well as the quality and characteristics of the imaging.

[0067] In this embodiment, by reasonably matching the surface shapes of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6, while meeting the requirements of the focal power of each lens and achieving the required optical performance indicators (such as long focal length, large aperture, and small volume), it is beneficial to further reduce the total length of the entire telephoto lens, thereby realizing a miniaturized lens design. In addition, while ensuring a large aperture, the path of light passing through the entire telephoto lens is made smoother, reducing unnecessary reflections and absorption, thereby further improving the light throughput and imaging quality while achieving a large aperture and high image quality.

[0068] It should be noted that, as Figures 1-3 shown, the object side surface of the third lens L3 is convex, and the image side surface of the fourth lens L4 is convex, which can make the overall structure of the third lens L3 and the fourth lens L4 more symmetrical, help to eliminate field curvature, enable the telephoto lens to obtain clearer imaging throughout the entire field of view, and optimize the image quality.

[0069] As a feasible implementation manner, the refractive index of the third lens L3 is Nd3, and the Abbe number is Vd3; the refractive index of the fourth lens L4 is Nd4, and the Abbe number is Vd4. Among them:

[0070] 1.47 ≤ Nd3 ≤ 1.84; 1.43 ≤ Nd4 ≤ 1.90;

[0071] 15.22 ≤ Vd3 ≤ 83.30; 23.21 ≤ Vd4 ≤ 95.00.

[0072] Among them, the refractive index is the ratio of the propagation speed of light in a vacuum to the propagation speed of light in this medium, which is mainly used to describe the refractive ability of the material to light, and the refractive indices of different materials are different.

[0073] The Abbe number is an index used to represent the dispersion ability of a transparent medium. The more severe the medium dispersion is, the smaller the Abbe number; on the contrary, the milder the medium dispersion is, the larger the Abbe number.

[0074] In this embodiment, the third lens L3 and the fourth lens L4 are combined with materials having different Abbe numbers and different refractive indices, which can make the dispersions of the third lens L3 and the fourth lens L4 compensate each other, achieve the purpose of eliminating chromatic aberration, and are beneficial to improving the imaging performance of the telephoto lens.

[0075] Continue to refer to Figure 2 and Figure 3 , as a feasible implementation manner, the third lens L3 and the fourth lens L4 form a cemented lens group G1.

[0076] Among them, as Figure 2 and Figure 3 shown, the third lens L3 and the fourth lens L4 are cemented to form a cemented lens group G1, which can minimize or eliminate chromatic aberration to fully correct the chromatic aberration of the telephoto lens. At the same time, it can also effectively reduce the air gap between the third lens L3 and the fourth lens L4, thereby further reducing the overall length of the lens.

[0077] In addition, the third lens L3 and the fourth lens L4 are glued together, which can also reduce the assembly components between the third lens L3 and the fourth lens L4, simplify the assembly procedure in the lens manufacturing process, reduce costs, and reduce the impact of tolerances such as tilt / eccentricity generated during the assembly process on the telephoto lens, thereby improving the stability of the telephoto lens.

[0078] Furthermore, by setting the object side surface of the third lens L3 to be convex and the image side surface of the fourth lens L4 to be convex, and in combination with the gluing of the third lens L3 and the fourth lens L4, the overall structure of the third lens L3 and the fourth lens L4 can be made more symmetrical, which helps to further optimize chromatic aberration and improve the color accuracy of imaging.

[0079] Among them, the third lens L3 and the fourth lens L4 can be bonded together with glue, which helps to simplify the assembly process, but is not limited to this.

[0080] Continue to refer to Figure 1 , as a feasible implementation manner, the distance between the third lens L3 and the fourth lens L4 on the optical axis is greater than 0.

[0081] Among them, there is an air gap between the third lens L3 and the fourth lens L4, which provides more design freedom and allows the distance between the lenses to be adjusted according to actual needs to optimize the optical performance.

[0082] At the same time, glued lenses may not be able to provide a large optical power, which is not sufficient to effectively control the light and direct it in the correct direction. In this embodiment, the third lens L3 and the fourth lens L4 are not glued together, which helps to achieve good convergence of light, making the structure of the telephoto lens more compact and lightweight.

[0083] In addition, if one of the lenses needs to be repaired or replaced, the air gap design can make the replacement process simpler.

[0084] Among them, the third lens L3 and the fourth lens L4 can be supported by a spacer washer, eliminating the need for special glue, which is beneficial to reducing the manufacturing cost.

[0085] As a feasible implementation manner, the first lens L1, the third lens L3, and the fourth lens L4 are all glass spherical lenses, and the second lens L2, the fifth lens L5, and the sixth lens L6 are all plastic aspherical lenses.

[0086] Among them, aspherical lenses can significantly reduce aberrations such as spherical aberration and coma, improving the imaging quality of the entire telephoto lens.

[0087] In this embodiment, the second lens L2, the fifth lens L5, and the sixth lens L6 are aspherical lenses, and the aspherical lenses are arranged at relatively critical positions in the telephoto lens, which helps to control light more effectively, reduce aberration, and thus improve the imaging performance of the entire telephoto lens.

[0088] Moreover, due to the good aberration correction ability of the above-mentioned aspherical lenses, it is beneficial to reduce the total number of lenses required in the telephoto lens, thereby simplifying the lens design, reducing the weight, and shrinking the volume.

[0089] Furthermore, the above-mentioned aspherical lenses can be made of plastic materials. Compared with glass lenses, plastic lenses can achieve lower costs, and plastic lenses are easier to be made into complex aspherical shapes.

[0090] Meanwhile, the first lens L1, the third lens L3, and the fourth lens L4 are spherical lenses, which helps to reduce costs and is easy to manufacture.

[0091] Furthermore, the above-mentioned spherical lenses can be glass spherical lenses. Among them, glass lenses have higher transmittance, can reduce the loss of light energy, and enable the imaging chip to receive higher light energy. In this embodiment, the first lens L1, the third lens L3, and the fourth lens L4 are glass spherical lenses, which is beneficial to make the telephoto lens have better imaging effects in low-light environments.

[0092] Meanwhile, glass lenses have the advantages of high hardness, strong wear resistance, long service life, and are not easily deformed by temperature, which can further make the performance of the telephoto lens more stable.

[0093] In addition, when the third lens L3 and the fourth lens L4 are cemented, the third lens L3 and the fourth lens L4 are glass lenses, which helps to further optimize chromatic aberration and improve the color accuracy of imaging.

[0094] It should be noted that in this embodiment, a combination of 3 glass spherical lenses and 3 plastic aspherical lenses is used, and with the cooperation of focal power distribution and material matching, a telephoto lens with a large aperture, a small volume, and low costs is realized. Further, by reasonably distributing the positions of the aspherical lenses and the spherical lenses, the optical quality of the telephoto lens can be significantly improved, while controlling the cost and weight, making it a high-performance and economical telephoto lens product.

[0095] Continue to refer to Figures 1-3 , as a feasible implementation manner, the telephoto lens further includes a diaphragm STO, and the diaphragm STO is located in the optical path between the first lens L1 and the second lens L2.

[0096] Among them, the diaphragm STO can determine the aperture size of the telephoto lens, and the setting position of the diaphragm STO will affect the generation and control of aberrations such as astigmatism and coma.

[0097] In this embodiment, the aperture STO is disposed in the optical path between the first lens L1 and the second lens L2, so that the aperture STO is set closer to the front end of the telephoto lens, thereby optimizing astigmatism and coma by controlling the light distribution entering the subsequent lenses, reducing the influence of astigmatism and coma while achieving a large aperture, and improving the imaging quality.

[0098] Continue to refer to Figures 1-3 , as a feasible implementation manner, the total length of the telephoto lens is TTL, and TTL ≤ 22 mm.

[0099] Among them, the total length TTL of the telephoto lens refers to the distance from the optical axis center of the object side of the first lens L1 to the image plane.

[0100] The telephoto lens provided in this embodiment has a total length TTL less than or equal to 22 mm, is structurally compact, and has good imaging performance, solving the problem that the telephoto lens is easily restricted by the installation space.

[0101] Continue to refer to Figures 1-3 , as a feasible implementation manner, the telephoto lens further includes a filter P, and the filter P is located on the image side of the sixth lens L6. Among them, the filter P can filter out unnecessary stray light, thereby further improving the image quality of the telephoto lens. At the same time, the filter P can also protect the imaging chip.

[0102] The following further describes a specific embodiment of the telephoto lens applicable to the above embodiment with reference to the accompanying drawings.

[0103] Embodiment 1

[0104] As Figure 1 shown, the telephoto lens provided in Embodiment 1 of the present invention includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 arranged in sequence along the optical axis from the object plane to the image plane.

[0105] The first lens L1 has a positive optical power, the second lens L2 has a negative optical power, the third lens L3 has a negative optical power, the fourth lens L4 has a positive optical power, the fifth lens L5 has a negative optical power, and the sixth lens L6 has a positive optical power.

[0106] The distance between the third lens L3 and the fourth lens L4 on the optical axis is greater than 0.

[0107] The aperture STO is located in the optical path between the first lens L1 and the second lens L2, and the filter P is located on the image side of the sixth lens L6.

[0108] Table 1 details the specific optical physical parameters of each lens in the telephoto lens provided in the first embodiment of the present utility model in a feasible implementation manner. The telephoto lens in Table 1 corresponds to Figure 1 the telephoto lens shown.

[0109] Table 1 Design values of the optical physical parameters of the telephoto lens

[0110]

[0111]

[0112] The surface numbers in Table 1 are numbered according to the surface order of each lens. Among them, "S1" represents the object side of the first lens, "S2" represents the image side of the first lens, and so on; "STO" represents the aperture stop of the telephoto lens. "IMA" represents the image plane of the telephoto lens; the radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface bends towards the image side, and a negative value represents that the surface bends towards the object side. Among them, "Infinity" represents that the surface is a plane and the radius of curvature is infinite, and the distance is infinite; the thickness represents the central axial distance from the current surface to the next surface; the refractive index Nd represents the ability of the material between the current surface and the next surface to deflect light, and a space represents that the current position is air and the refractive index is 1; the Abbe number Vd represents the dispersion characteristics of the material between the current surface and the next surface to light, and a space represents that the current position is air; the semi-diameter represents the effective diameter of the light of the lens; the k value represents the numerical value of the conic coefficient of the aspherical surface.

[0113] In this embodiment, the aspherical conic coefficient of the aspherical lens in the telephoto lens can be defined by the following aspherical formula, but is not limited to the following representation methods:

[0114]

[0115] where z is the axial sagittal height in the Z direction of the aspherical surface; r is the height of the aspherical surface; c is the curvature of the fitted spherical surface, numerically the reciprocal of the radius of curvature; k is the fitted conic coefficient; A - G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial respectively.

[0116] Exemplarily, Table 2 details the aspherical coefficients of each lens in this embodiment in a feasible implementation manner.

[0117] Table 2 Design values of the aspherical coefficients of each lens in the telephoto lens

[0118]

[0119] For the telephoto lens provided in the first embodiment, its overall optical length TTL is 21.83 mm.

[0120] Figure 4 This is the spherical aberration curve graph of the telephoto lens provided in the first embodiment of the present invention. Among them, the vertical direction in the figure represents the normalization of the aperture, 0 represents on the optical axis, and the vertex in the vertical direction represents the maximum pupil radius; the horizontal direction is the spherical aberration of different wavelengths, with the unit of millimeter (mm); different linear curves in the figure represent different wavelengths of the telephoto lens imaging. As Figure 4 It can be seen that the pupil radius is 3.7451 mm, and the axial aberrations at different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm) are all controlled within the range of (-0.05 mm, +0.05 mm), indicating that the spherical aberration of the telephoto lens at each wavelength is well controlled and can meet the requirements of wide-spectrum applications.

[0121] Embodiment 2

[0122] As Figure 2 shown, the telephoto lens provided in the second embodiment of the present invention includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 arranged in sequence along the optical axis from the object plane to the image plane.

[0123] The first lens L1 has a positive optical power, the second lens L2 has a negative optical power, the third lens L3 has a positive optical power, the fourth lens L4 has a negative optical power, the fifth lens L5 has a negative optical power, and the sixth lens L6 has a positive optical power.

[0124] The third lens L3 and the fourth lens L4 form a cemented lens group G1.

[0125] The aperture stop STO is located in the optical path between the first lens L1 and the second lens L2, and the filter P is located on the image side of the sixth lens L6.

[0126] Table 3 details the specific optical physical parameters of each lens in the telephoto lens provided in the second embodiment of the present invention in a feasible implementation manner. The telephoto lens in Table 3 corresponds to Figure 2 the shown telephoto lens.

[0127] Table 3 Design values of the optical physical parameters of the telephoto lens

[0128]

[0129]

[0130] The surface numbers in Table 3 are numbered according to the surface order of each lens. Among them, "S1" represents the object side of the first lens, "S2" represents the image side of the first lens, and so on; "STO" represents the aperture of the telephoto lens. "IMA" represents the image plane of the telephoto lens; the radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface bends towards the image plane side, and a negative value represents that the surface bends towards the object plane side. Among them, "Infinity" represents that the surface is a plane, the radius of curvature is infinite, and the distance is infinite; the thickness represents the central axial distance from the current surface to the next surface; the refractive index Nd represents the ability of the material between the current surface and the next surface to deflect light, and a space represents that the current position is air and the refractive index is 1; the Abbe number Vd represents the dispersion characteristics of the material between the current surface and the next surface to light, and a space represents that the current position is air; the semi-diameter represents the effective diameter of the light of the lens; the k value represents the numerical value of the conic coefficient of the aspherical surface.

[0131] In this embodiment, the aspherical conic coefficient of the aspherical lens in the telephoto lens can be defined by the following aspherical formula, but is not limited to the following representation:

[0132]

[0133] Among them, z is the axial sagittal height in the Z direction of the aspherical surface; r is the height of the aspherical surface; c is the curvature of the fitted spherical surface, which is numerically the reciprocal of the radius of curvature; k is the fitted conic coefficient; A - G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspherical polynomial respectively.

[0134] Exemplarily, Table 4 details the aspherical coefficients of each lens in the second embodiment in a feasible implementation manner.

[0135] Table 4 Design values of aspherical coefficients of each lens in the telephoto lens

[0136]

[0137] For the telephoto lens provided in the second embodiment, its overall optical length TTL is 21.98 mm.

[0138] Figure 5 This is the spherical aberration curve graph of the telephoto lens provided in the second embodiment of the present invention. Among them, the vertical direction in the graph represents the normalization of the aperture, 0 represents on the optical axis, and the vertex in the vertical direction represents the maximum pupil radius; the horizontal direction is the spherical aberration of different wavelengths, with the unit of millimeter (mm); the different linear curves in the graph represent the different wavelengths of the telephoto lens imaging. As Figure 5It can be seen that the pupil radius is 3.7025 mm, and the axial aberrations at different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm) are all controlled within the range of (-0.05 mm, +0.05 mm), indicating that the spherical aberration of this telephoto lens at each wavelength is well controlled and can meet the requirements of wide-spectrum applications.

[0139] Embodiment III

[0140] As Figure 3 shown, the telephoto lens provided in Embodiment III of the present utility model includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 arranged in sequence along the optical axis from the object plane to the image plane.

[0141] The first lens L1 has a positive optical power, the second lens L2 has a negative optical power, the third lens L3 has a negative optical power, the fourth lens L4 has a positive optical power, the fifth lens L5 has a negative optical power, and the sixth lens L6 has a positive optical power.

[0142] The third lens L3 and the fourth lens L4 form a cemented lens group G1.

[0143] The aperture stop STO is located in the optical path between the first lens L1 and the second lens L2, and the filter P is located on the image side of the sixth lens L6.

[0144] Table 5 details the specific optical and physical parameters of each lens in the telephoto lens provided in Embodiment III of the present utility model in a feasible implementation manner. The telephoto lens in Table 5 corresponds to Figure 3 the shown telephoto lens.

[0145] Table 5 Design values of the optical and physical parameters of the telephoto lens

[0146]

[0147] The surface numbers in Table 5 are numbered according to the surface order of each lens. Among them, "S1" represents the object side of the first lens, "S2" represents the image side of the first lens, and so on; "STO" represents the aperture of the telephoto lens. "IMA" represents the image plane of the telephoto lens; the radius of curvature represents the degree of curvature of the lens surface. A positive value represents that the surface bends towards the image side, and a negative value represents that the surface bends towards the object side. Among them, "Infinity" represents that the surface is a plane, the radius of curvature is infinite, and the distance is infinite; the thickness represents the central axial distance from the current surface to the next surface; the refractive index Nd represents the ability of the material between the current surface and the next surface to deflect light, and a space represents that the current position is air and the refractive index is 1; the Abbe number Vd represents the dispersion characteristics of the material between the current surface and the next surface to light, and a space represents that the current position is air; the semi-diameter represents the effective diameter of the light of the lens; the k value represents the numerical value of the conic coefficient of the aspheric surface.

[0148] In this embodiment, the aspheric conic coefficient of the aspheric lens in the telephoto lens can be defined by the following aspheric formula, but is not limited to the following representation:

[0149]

[0150] Among them, z is the axial sagittal height in the Z direction of the aspheric surface; r is the height of the aspheric surface; c is the curvature of the fitted spherical surface, which is numerically the reciprocal of the radius of curvature; k is the fitted conic coefficient; A - G are the coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspheric polynomial respectively.

[0151] Exemplarily, Table 6 details the aspheric coefficients of each lens in the third embodiment in a feasible implementation manner.

[0152] Table 6 Design values of the aspheric coefficients of each lens in the telephoto lens

[0153]

[0154] For the telephoto lens provided in the third embodiment, its overall optical length TTL is 21.82 mm.

[0155] Figure 6 This is the spherical aberration curve graph of the telephoto lens provided in the third embodiment of the present invention. Among them, the vertical direction in the graph represents the normalization of the aperture, 0 represents on the optical axis, and the vertex in the vertical direction represents the maximum pupil radius; the horizontal direction is the spherical aberration of different wavelengths, with the unit of millimeter (mm); the different linear curves in the graph represent the different wavelengths of the imaging of the telephoto lens. As Figure 6It can be seen that the pupil radius is 3.6710 mm, and the axial aberrations at different wavelengths (0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm) are all controlled within the range of (-0.05 mm, +0.05 mm), indicating that the spherical aberration of the telephoto lens at each wavelength is well controlled and can meet the requirements of wide-spectrum applications.

[0156] To illustrate the above embodiments more clearly, Table 7 details the specific optical physical parameters of each lens in the telephoto lenses provided in Embodiments 1 to 3 of the present invention.

[0157] Table 7 Design values of the optical physical parameters of the telephoto lens

[0158]

[0159] The above specific implementation manners do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A telephoto lens, characterized in that: It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are arranged in sequence from the object plane to the image plane along the optical axis; The first lens has positive optical power, the second lens has negative optical power, the third lens has optical power, the fourth lens has optical power, the fifth lens has negative optical power, and the sixth lens has positive optical power; The focal power of the telephoto lens is φ, the focal power of the first lens is φ1, the focal power of the second lens is φ2, the focal power of the third lens is φ3, the focal power of the fourth lens is φ4, the focal power of the fifth lens is φ5, and the focal power of the sixth lens is φ6; 0.35≤φ1 / φ≤0.67; -0.85≤φ2 / φ≤-0.53; -1.14≤φ3 / φ≤2.12; -1.83≤φ4 / φ≤2.49; -1.03≤φ5 / φ≤-0.56; 1.06≤φ6 / φ≤1.

50.

2. The telephoto lens according to claim 1, characterized in that: The third lens has negative refractive power, and the fourth lens has positive refractive power.

3. The telephoto lens according to claim 1, characterized in that: The third lens has positive refractive power, and the fourth lens has negative refractive power.

4. The telephoto lens according to claim 1, wherein: The object side surface of the first lens is a convex surface; The object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; The object side surface of the third lens is a convex surface; The image side surface of the fourth lens is a convex surface; The object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface; The object-side surface of the sixth lens is convex, and the image-side surface of the sixth lens is concave.

5. The telephoto lens according to claim 1, characterized in that: The refractive index of the third lens is Nd3, and the Abbe number is Vd3; the refractive index of the fourth lens is Nd4, and the Abbe number is Vd4; 1.47≤Nd3≤1.84; 1.43≤Nd4≤1.90; 15.22≤Vd3≤83.30; 23.21≤Vd4≤95.

00.

6. The telephoto lens according to claim 1, wherein: The third lens and the fourth lens form a cemented lens group.

7. The telephoto lens according to claim 1, wherein: The distance between the third lens and the fourth lens on the optical axis is greater than 0.

8. The telephoto lens according to claim 1, wherein: The first lens, the third lens and the fourth lens are all glass spherical lenses; the second lens, the fifth lens and the sixth lens are all plastic aspherical lenses.

9. The telephoto lens according to claim 1, wherein: The telephoto lens also includes an aperture; The aperture stop is located in the optical path between the first lens and the second lens.

10. The telephoto lens according to claim 1, wherein: The total length of the telephoto lens is TTL, TTL≤22mm.

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