Large-target-surface large-aperture telephoto lens
By designing a large-aperture telephoto lens with a large target area, and employing an eight-element optical power distribution and an aspherical lens combination, the problem of image distortion in smartphones under low-light conditions was solved, achieving high-quality imaging effects and low-cost production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2026-03-24
AI Technical Summary
Traditional smartphones, due to limitations in body thickness and module space, struggle to achieve compatibility between large apertures and telephoto lenses, resulting in distorted image details in low-light conditions and reduced aperture affecting image quality.
Design a large-aperture telephoto lens with a large target area, using eight lens elements with positive-positive-negative-negative-positive-positive-negative configurations, combined with glass and plastic aspherical lenses, controlling the light throughput through an aperture stop, and optimizing the lens shape and power ratio to achieve imaging performance with a large aperture and large target area.
It achieves clear imaging under low-light conditions, reduces the number of lenses and manufacturing costs, improves imaging quality and stability, and adapts to imaging needs in different temperature environments.
Smart Images
Figure CN224035691U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of optical lens technology, and in particular to a large-aperture telephoto lens with a large target area. Background Technology
[0002] With the popularization and professionalization of smartphone photography functions, users' demand for telephoto imaging has increased significantly.
[0003] Traditional smartphones, limited by body thickness and module space, are forced to reduce the aperture to achieve telephoto capabilities, resulting in detail loss in low-light scenes. Furthermore, traditional telephoto lenses require a large image space to accommodate large-area sensors, but smartphones have compact internal layouts, and the module height is usually compressed, making it difficult to ensure compatibility between sensor size and telephoto optical path. Utility Model Content
[0004] This invention provides a large-aperture telephoto lens with a large target area to meet the increasingly high demands of modern smartphones for telephoto shooting capabilities.
[0005] In a first aspect, the present invention provides a large-aperture telephoto lens with a large target area, comprising, along the optical axis from the object side to the image side, a first lens with positive optical power, a second lens with positive optical power, a third lens with negative optical power, a fourth lens with negative optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power.
[0006] The first lens and the sixth lens are glass aspherical lenses, while the remaining lenses are plastic aspherical lenses.
[0007] Optionally, the object-side surface of the first lens is convex, and the image-side surface is convex.
[0008] The second lens has a convex object-side surface and a concave image-side surface;
[0009] The object side of the third lens is convex, and the image side is concave.
[0010] The fourth lens has a concave side and a convex side;
[0011] The object side of the fifth lens is concave, and the image side is also concave.
[0012] The object side of the sixth lens is convex, and the image side is also convex.
[0013] The object side of the seventh lens is convex, and the image side is also convex.
[0014] The object side of the eighth lens is concave, and the image side is also concave.
[0015] Optionally, each lens in the long-focus lens satisfies the following condition:
[0016]
[0017] wherein, respectively, focal power of the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens; is the focal power of the long-focus lens.
[0018] Optionally, the first lens, the second lens, the fourth lens and the fifth lens satisfy the following condition:
[0019]
[0020] wherein, respectively, focal power of the first lens, the second lens, the fourth lens and the fifth lens, is the focal power of the long-focus lens.
[0021] Optionally, the first lens satisfies the following condition: 1.854≤TTL / ΦL1≤1.924;
[0022] wherein, TTL is the total optical length of the long-focus lens, ΦL1 is the lens diameter of the first lens.
[0023] Optionally, the eighth lens satisfies the following condition: 1.185≤TTL / ΦL8≤1.206;
[0024] wherein, TTL is the total optical length of the long-focus lens, ΦL8 is the lens diameter of the eighth lens.
[0025] Optionally, the long-focus lens satisfies the following condition: 14.519≤TTL / BFL≤15.434;
[0026] wherein, BFL is the back focus of the long-focus lens, TTL is the total optical length of the long-focus lens.
[0027] Optionally, the long-focus lens satisfies the following condition:
[0028] 3.980<f6 / CT6<4.280;
[0029] -10.687<f8 / CT8<-10.095;
[0030] wherein, f6 is the focal length of the sixth lens, f8 is the focal length of the eighth lens, CT6 is the center thickness of the sixth lens, CT8 is the center thickness of the eighth lens.
[0031] Optionally, the long-focus lens satisfies the condition: FNO≤1.397.
[0032] Wherein, FNO is the F-number of the long-focus lens.
[0033] Optionally, a diaphragm is further included, and the diaphragm is located on the object side of the first lens.
[0034] In the zoom lens provided by the embodiment of the present application, the first lens, the second lens, the sixth lens and the seventh lens have positive focal power, while the third lens, the fourth lens, the fifth lens and the eighth lens have negative focal power, which is actually to distribute the focal power of the eight lenses of positive-positive-negative-negative-negative-positive-positive-negative, so that the light can pass through the optical system relatively gently, the distribution of aberration is balanced, the light flux is controlled, the imaging surface is adjusted, and thus the imaging performance of a large aperture and a large target surface is realized. Moreover, the eight lenses are all aspherical lenses, which can utilize the aspherical surface type to better correct aberration, reduce distortion, increase illumination and reduce the number of lenses of the optical system. Furthermore, in the embodiment of the present application, the lens at the front end of the lens, i.e., the first lens, and the middle key lens at the waist, i.e., the sixth lens, are set as glass lenses, which can utilize the characteristics of glass material, on the one hand, realize a larger Abbe number, which is conducive to eliminating chromatic aberration, and on the other hand, can reduce the sensitivity of imaging to temperature and reduce the deformation degree of the lens at different temperatures, so that clear imaging can be ensured under high and low temperature environments; and the remaining six lenses except the first lens and the sixth lens are set as plastic lenses, i.e., when the aspherical lenses are prepared, the advantage of lower preparation difficulty of plastic lenses can be utilized, which is helpful to reduce the manufacturing cost and realize mass production, and has the advantages of low price, easy processing and light weight. BRIEF DESCRIPTION OF DRAWINGS
[0035] Figure 1 is a structure schematic view of a large-aperture long-focus lens with a large target surface provided by an embodiment of the present application;
[0036] Figure 2 is an axial aberration curve of the long-focus lens shown in FIG. 1; Figure 1
[0037] is a field curvature distortion graph of the long-focus lens shown in FIG. 1; Figure 3 Figure 1 is an axial aberration curve of the long-focus lens shown in FIG. 2;
[0038] Figure 4 Figure 1 is a field curvature distortion graph of the long-focus lens shown in FIG. 2;
[0039] Figure 5 is a structure schematic view of a large-aperture long-focus lens with a large target surface provided by an embodiment of the present application;
[0040] Figure 6 is a schematic view of the axial aberration curve of the long-focus lens shown in Figure 5
[0041] Figure 7 is a schematic view of the field curvature distortion graph of the long-focus lens shown in Figure 5
[0042] Figure 8 is a schematic view of the axial aberration curve of the long-focus lens shown in Figure 5
[0043] Figure 9 is a schematic view of the axial aberration curve of the long-focus lens shown in
[0044] Figure 10 is a schematic view of the field curvature distortion graph of the long-focus lens shown in Figure 9
[0045] Figure 11 is a schematic view of the field curvature distortion graph of the long-focus lens shown in Figure 9
[0046] Figure 12 is a schematic view of the field curvature distortion graph of the long-focus lens shown in Figure 9 DETAILED DESCRIPTION
[0047] The utility model will be further described in detail below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the utility model, and not to limit the utility model. In addition, it should be noted that in order to facilitate the description, only the part related to the utility model is shown in the drawings, not all structures.
[0048] The terms used in the embodiments of the utility model are only for the purpose of describing specific embodiments, and are not intended to limit the utility model. It should be noted that the "up", "down", "left", "right" and other orientation words described in the embodiments of the utility model are described with the angle shown in the drawings, and should not be understood as limiting the embodiments of the utility model. In addition, in the context, it should also be understood that when referring to an element formed "on" or "under" another element, it can be directly formed "on" or "under" another element, or indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second" and the like are only for the purpose of description, and do not represent any order, quantity or importance, but only to distinguish different components. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.
[0049] The term "comprising" and its variations as used in this utility model are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".
[0050] It should be noted that the concepts of "first" and "second" mentioned in this utility model are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.
[0051] It should be noted that the terms "a" and "a plurality of" used in this utility model are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".
[0052] Figure 1 This is a schematic diagram of the structure of a large-aperture telephoto lens according to Embodiment 1 of this utility model, for reference. Figure 1 The telephoto lens includes, along the optical axis from the object side to the image side, a first lens 10 with positive optical power, a second lens 20 with positive optical power, a third lens 30 with negative optical power, a fourth lens 40 with negative optical power, a fifth lens 50 with negative optical power, a sixth lens 60 with positive optical power, a seventh lens 70 with positive optical power, and an eighth lens 80 with negative optical power.
[0053] Among them, the first lens 10 and the sixth lens 60 are glass aspherical lenses, and the remaining lenses are plastic aspherical lenses.
[0054] First, for optical lenses, optical power equals the difference between the image-side beam convergence and the object-side beam convergence; it characterizes the optical system's ability to deflect light. The larger the absolute value of optical power, the stronger the bending ability of light; the smaller the absolute value, the weaker the bending ability. When optical power is positive, the refraction of light is converging; when optical power is negative, the refraction of light is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system formed by multiple lenses (i.e., a lens group).
[0055] In the zoom lens provided in this embodiment, each lens can be fixed in a lens barrel. Figure 1 (not shown in the image) such as Figure 1As shown, the first lens 10, the second lens 20, the sixth lens 60 and the seventh lens 70 are set to have positive focal power, while the third lens 30, the fourth lens 40, the fifth lens 50 and the eighth lens 80 are set to have negative focal power, which is essentially to distribute the focal power of the eight lenses as positive-positive-negative-negative-negative-positive-positive-negative, so that the light can pass through the optical system more gently, balance the distribution of aberration, control the light flux, adjust the imaging surface, thereby realizing the imaging performance of large aperture and large target surface. In addition, the eight lenses are all aspherical lenses, which can utilize the aspherical surface type to better correct aberration, reduce distortion, increase illumination and reduce the number of lenses of the optical system.
[0056] Furthermore, in the embodiment of the present application, the lens at the front end of the lens, i.e. the first lens 10, and the middle key lens at the waist, i.e. the sixth lens 60, are set as glass lenses, which can utilize the characteristics of glass material, on the one hand to realize a larger Abbe number, which is conducive to eliminating chromatic aberration, and on the other hand to reduce the sensitivity of imaging to temperature and reduce the deformation degree of the lens at different temperatures, so as to ensure clear imaging in high and low temperature environments; and the remaining six lenses except the first lens 10 and the sixth lens 60 are set as plastic lenses, which can utilize the advantage of lower preparation difficulty of plastic lenses when preparing the aspherical lenses, which helps to reduce the manufacturing cost and realize mass production, and has the advantages of low price, easy processing and light weight.
[0057] Continuing to refer to Figure 1 In a specific embodiment, the telephoto lens further comprises a diaphragm 90, and the diaphragm 90 is located at the object side of the first lens 10.
[0058] The diaphragm 90 is used to limit the beam size in the optical system, which determines how much light passes through the lens into the photosensitive element, i.e. for controlling the light quantity of the lens, i.e. the diaphragm 90 directly determines the size of the aperture of the telephoto lens. The diaphragm 90 in the embodiment of the present application is arranged at the object side of the first lens 10, which directly controls the light quantity by using the first end position of the entire optical system, and on the basis of effectively limiting the size of the aperture of the optical system, ensures the amount of light passing through the diaphragm 90, and ensures the imaging brightness.
[0059] In a specific embodiment, the object side of the first lens 10 is a convex surface, and the image side is a convex surface; the object side of the second lens 20 is a convex surface, and the image side is a concave surface; the object side of the third lens 30 is a convex surface, and the image side is a concave surface; the object side of the fourth lens 40 is a concave surface, and the image side is a convex surface; the object side of the fifth lens 50 is a concave surface, and the image side is a concave surface; the object side of the sixth lens 60 is a convex surface, and the image side is a convex surface; the object side of the seventh lens 70 is a convex surface, and the image side is a convex surface; the object side of the eighth lens 80 is a concave surface, and the image side is a concave surface.
[0060] In this embodiment, the specific shapes of the front and rear surfaces of each lens are limited to convex or concave to control various aberrations by utilizing the specific morphology of each lens surface. For example, by setting the object-side surface of the first lens 10 to convex and the image-side surface of the eighth lens 80 to concave, i.e., adopting a front-convex and rear-concave structure, the convex front surface can be used to quickly focus light, reducing the size of the rear lens group, while avoiding the decrease in edge resolution due to beam divergence. The concave rear surface can be used to quickly converge the beam, shortening the physical length and reducing the overall optical length and volume. As another example, by setting the front surfaces of the second lens 20 and the third lens 30 in the front group to be convex and the rear surfaces to be concave, the strong refraction at the edges of the convex surface can easily cause spherical aberration, which can be partially offset by the concave surface, thereby achieving a balance of spherical aberration.
[0061] In one specific embodiment, optionally, the lenses in the telephoto lens satisfy the following conditions:
[0062]
[0063] in, The optical powers of the first lens 10, the third lens 30, the fourth lens 40, the fifth lens 50, the sixth lens 60, the seventh lens 70, and the eighth lens 80 are respectively. This refers to the optical focal length of a telephoto lens.
[0064] Specifically, optical power determines the ability of an optical system to deflect light. In this embodiment, the optical power range of each lens is designed to meet the specific proportional distribution mentioned above, which can simultaneously achieve a large aperture and a large target surface; ensure the balance of the incident angle of the front and rear lenses to reduce the sensitivity of the lenses to manufacturing tolerances; and also help reduce distortion and improve the stability of the lens.
[0065] In one specific embodiment, the first lens 10, the second lens 20, the fourth lens 40, and the fifth lens 50 may further satisfy the following conditions:
[0066]
[0067] in, The optical powers of the first lens 10, the second lens 20, the fourth lens 40, and the fifth lens 50 are respectively. This refers to the optical focal length of a telephoto lens.
[0068] In this system, the first lens 10 and the second lens 20 are both positive lenses, which converge light rays. The fourth lens 40 and the fifth lens 50 are negative lenses, which diverge light rays. By properly setting the optical power of the first lens 10, the second lens 20, the fourth lens 40, and the fifth lens 50, it is beneficial to improve image quality, reduce tolerance sensitivity, and increase the yield rate of manufactured products.
[0069] In a specific embodiment, optionally, the first lens 10 satisfies the following condition: 1.854≤TTL / ΦL1≤1.924; wherein TTL is the total optical length of the telephoto lens, and ΦL1 is the lens diameter of the first lens 10.
[0070] In a specific embodiment, optionally, the eighth lens 80 satisfies the following condition: 1.185≤TTL / ΦL8≤1.206; wherein TTL is the total optical length of the telephoto lens, and ΦL8 is the lens diameter of the eighth lens 80.
[0071] In the above two embodiments, by reasonably setting the ratio range of the lens diameter and the total optical length of the first lens 10 and the eighth lens 80, the volume of the entire lens can be effectively controlled, so that the lens meets the miniaturization requirement. In addition, the lens diameter of the first lens 10 and the eighth lens 80 is reasonably selected, which is beneficial to realize a larger field of view and a larger target surface, and improve the light intake.
[0072] In a specific embodiment, optionally, the telephoto lens satisfies the following condition:
[0073] 14.519≤TTL / BFL≤15.434; wherein BFL is the back focus of the telephoto lens, and TTL is the total optical length of the telephoto lens.
[0074] In this embodiment, by reasonably setting the ratio range of the back focus and the total optical length of the telephoto lens, the eighth lens 80, which is the last lens, can have a longer distance from the image surface, thereby reserving sufficient space for the installation of the bottom optical sensor and the flat color filter.
[0075] In a specific embodiment, optionally, the telephoto lens satisfies the following condition: 3.980<f6 / CT6<4.280; -10.687<f8 / CT8<-10.095; wherein f6 is the focal length of the sixth lens 60, f8 is the focal length of the eighth lens 80, CT6 is the center thickness of the sixth lens 60, and CT8 is the center thickness of the eighth lens 80.
[0076] In this embodiment, by reasonably setting the ratio range of the core thickness and the focal length of the sixth lens 60 and the eighth lens 80, the core thickness is matched with the focal length, which can control the wavefront difference between light beams to a certain extent, avoid excessive wavefront phase difference, and achieve the effect of optimizing the imaging quality.
[0077] In a specific embodiment, optionally, the telephoto lens satisfies the following condition: FNO≤1.397; wherein FNO is the aperture number of the telephoto lens.
[0078] Wherein, the F-number can be used to measure the light amount, and smaller F-number will bring more light amount, by setting FNO to meet the above condition, it indicates that the long-focus lens can have a large aperture, which is very beneficial to clear imaging.
[0079] In conclusion, the embodiment of the utility model discloses a combination of two glass aspheric lenses and six plastic aspheric lenses, and the optimization of parameters such as optical power, shape and assembly gap, which can improve the light throughput of the entire optical system, realize large aperture, large target surface, high image quality and low distortion imaging capability, and ultimately realize a long-focus lens with a focal length of 13mm, an optical total length of 18mm, an F-number of FNO 1.4 and a target surface of 16.2mm.
[0080] Based on the same concept, the utility model provides three different specific embodiments, and the optical power relationship and related physical optical parameter design range are shown in Table 1:
[0081] Table 1 related physical optical parameters in each embodiment
[0082]
[0083] In the first embodiment of the utility model, reference Figure 1 It can be known that the structure of each element of the system and the shape and position of each element are very important to the system. As shown in the figure, the optical system is composed of eight optical lenses, wherein the diaphragm 90 is located at the object side of the first lens 10. A plane glass 100 is arranged from the object plane to the image plane; the plane glass 100 is located on the image side surface of the eighth lens 80, and the plane glass 100 can protect the photosensitive chip in the imaging sensor, wherein the imaging chip is used to convert the optical signal collected by the long-focus lens into an electrical signal, thereby ensuring the imaging effect of the long-focus lens. Specifically, in the first embodiment, the focal length f of the long-focus lens is 12.921, the FNO (i.e. the F-number) is 1.394, the total length is 17.988mm, and the image size is 16.200mm.
[0084] As Figure 1 The parameter design value of each lens in the long-focus lens of the first embodiment is shown in Table 2:
[0085]
[0086]
[0087] The surface numbers in Table 2 are assigned according to the surface sequence of each lens. For example, surface S1 represents the object side of the first lens 10, and surface S2 represents the image side of the first lens 10. “STOP” represents the aperture stop 90° of the lens; the radius of curvature represents the degree of curvature of the corresponding lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. “Infinity” indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; and a blank space indicates that the current position is air.
[0088] The aspherical lenses in Table 2 satisfy the following formula:
[0089]
[0090] Where Z is the sag of the aspherical surface, c is the fundamental curvature at the vertex, k is the conic section constant, r is the radial coordinate perpendicular to the optical axis, and a i a is the coefficient of the higher-order term. i r 2i For aspherical surfaces, there are multiple terms.
[0091] The coefficient values of each aspherical surface in the above embodiment 1 are shown in Table 3:
[0092]
[0093]
[0094] Where 1.032E-04 indicates that the coefficient a2 of surface number S1 is 1.032 * 10^6. -4 And so on.
[0095] Figure 2 for Figure 1 The diagram shows the axial aberration curves of a telephoto lens. The vertical direction represents the normalized aperture, with 0 indicating the maximum pupil radius at the vertical vertex on the optical axis. The horizontal direction represents the offset relative to the ideal focus, expressed in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system image, derived from... Figure 2 It can be seen that the axial aberrations of the normalized apertures for different visible light wavelengths from 0 to 1.0 are all controlled within a certain range, indicating that the spherical aberration of the optical system is well controlled at each wavelength.
[0096] Figure 3 for Figure 1The field curvature distortion chart of the long-focus lens is shown in the figure, wherein, in the left coordinate system, the horizontal coordinate represents the size of the field curvature, with unit of mm; the vertical coordinate represents the normalized image height without unit; in the right coordinate system, the horizontal coordinate represents the size of the distortion (F-Tan(Theta)), with unit of %; and the vertical coordinate represents the normalized image height without unit. Figure 3 It can be seen that the long-focus lens provided by the embodiment effectively controls the field curvature from light with wavelength of 0.435 μm to light with wavelength of 0.650 μm, that is, the difference between the best imaging planes of the central field of view and the edge field of view is small when imaging; the F-Tan(Theta) distortion of the long-focus lens is within 5%, the imaging distortion is reasonable, and general requirements are met.
[0097] Figure 4 For Figure 1 The axial chromatic aberration chart of the long-focus lens is shown in the figure, wherein, the vertical direction represents the normalized aperture, 0 represents on the optical axis, and the axial direction vertex represents the maximum pupil radius; the main wavelength uses 555 nm, and the horizontal direction represents the offset amount relative to the main wavelength, with unit of microns (um). From Figure 4 It can be seen that the axial chromatic aberration of different wavelengths is controlled within a reasonable range, which shows that the axial chromatic aberration of the long-focus lens is well controlled and can meet the application requirements of the visible light band.
[0098] Figure 5 It is a structure schematic diagram of a large-target large-aperture long-focus lens provided by the embodiment two of the utility model, in the embodiment two of the utility model, referring to Figure 5 It can be known that the optical system is also composed of 8 optical lenses, wherein, the diaphragm 90 is located at the fourth lens 40 object side position. A plane glass 100 is further arranged along the object plane to the image plane; the plane glass 100 is located on one side of the image surface of the eighth lens 80, and the plane glass 100 can protect the photosensitive chip in the imaging sensor, wherein, the imaging chip is used to convert the optical signal collected by the long-focus lens into an electrical signal, thereby ensuring the imaging effect of the long-focus lens. Specifically, in the embodiment one, the focal length f of the long-focus lens is 13.231, the FNO (i.e. the aperture number) is 1.397, the total length is 18.292 mm, and the image plane size
[0099] As Figure 5 The parameter design value of each lens in the long-focus lens of the embodiment two is shown in table 4:
[0100]
[0101]
[0102] The surface numbers in Table 4 are assigned according to the surface sequence of each lens. For example, surface S1 represents the object side of the first lens 10, and surface S2 represents the image side of the first lens 10. “STOP” represents the aperture stop 90° of the lens; the radius of curvature represents the degree of curvature of the corresponding lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. “Infinity” indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; and a blank space indicates that the current position is air.
[0103] The aspherical lenses in Table 4 satisfy the following formula:
[0104]
[0105] Where Z is the sag of the aspherical surface, c is the fundamental curvature at the vertex, k is the conic section constant, r is the radial coordinate perpendicular to the optical axis, and a i a is the coefficient of the higher-order term. i r 2i For aspherical surfaces, there are multiple terms.
[0106] The coefficient values of each aspherical surface in the above embodiment 1 are shown in Table 5:
[0107]
[0108]
[0109] Where 1.163E-04 indicates that the coefficient a2 of surface number S1 is 1.163 * 10^6. -4 And so on.
[0110] Figure 6 for Figure 5 The diagram shows the axial aberration curves of a telephoto lens. The vertical direction represents the normalized aperture, with 0 indicating the maximum pupil radius at the vertical vertex on the optical axis. The horizontal direction represents the offset relative to the ideal focus, expressed in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system image, derived from... Figure 6 It can be seen that the axial aberrations of the normalized apertures for different visible light wavelengths from 0 to 1.0 are all controlled within a certain range, indicating that the spherical aberration of the optical system is well controlled at each wavelength.
[0111] Figure 7 for Figure 5The field curvature distortion chart of the long-focus lens is shown in the figure, wherein, in the left coordinate system, the horizontal coordinate represents the size of the field curvature, with unit of mm; the vertical coordinate represents the normalized image height without unit; in the right coordinate system, the horizontal coordinate represents the size of the distortion (F-Tan(Theta)), with unit of %; and the vertical coordinate represents the normalized image height without unit. Figure 7 It can be seen that the long-focus lens provided by the embodiment effectively controls the field curvature from light with wavelength of 0.435 μm to light with wavelength of 0.650 μm, that is, the difference between the best imaging planes of the central field of view and the edge field of view is small when imaging; the F-Tan(Theta) distortion of the long-focus lens is within 5%, the imaging distortion is reasonable, and general requirements are met.
[0112] Figure 8 For Figure 5 The axial chromatic aberration chart of the long-focus lens is shown in the figure, wherein, the vertical direction represents the normalized aperture, 0 represents on the optical axis, and the axial direction top represents the maximum pupil radius; the main wavelength uses 555 nm, and the horizontal direction represents the offset amount relative to the main wavelength, with unit of micrometers (um). From Figure 8 It can be seen that the axial chromatic aberration of different wavelengths is controlled within a reasonable range, which indicates that the axial chromatic aberration of the long-focus lens is well controlled and can meet the application requirements of the visible light band.
[0113] Figure 9 It is a structure schematic diagram of a large-target large-aperture long-focus lens provided by the embodiment three of the utility model, in the embodiment three of the utility model, referring to Figure 9 It can be known that the optical system is also composed of 8 optical lenses, wherein, the diaphragm 90 is located at the fourth lens 40 object side position. A plane glass 100 is further arranged along the object plane to the image plane; the plane glass 100 is located on the image side surface of the eighth lens 80, and the plane glass 100 can protect the photosensitive chip in the imaging sensor, wherein, the imaging chip is used to convert the optical signal collected by the long-focus lens into an electrical signal, thereby ensuring the imaging effect of the long-focus lens. Specifically, in the embodiment one, the focal length f of the long-focus lens is 13.190, the FNO (i.e. the aperture number) is 1.393, the total length is 18.288, and the image plane size
[0114] As Figure 9 The parameter design values of each lens in the long-focus lens of the embodiment three are shown in table 6:
[0115]
[0116]
[0117] The surface numbers in Table 6 are assigned according to the surface sequence of each lens. For example, surface S1 represents the object side of the first lens 10, and surface S2 represents the image side of the first lens 10. “STOP” represents the aperture stop 90° of the lens; the radius of curvature represents the degree of curvature of the corresponding lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. “Infinity” indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface; the refractive index represents the ability of the material between the current surface and the next surface to deflect light; and a blank space indicates that the current position is air.
[0118] The aspherical lenses in Table 6 satisfy the following formula:
[0119]
[0120] Where Z is the sag of the aspherical surface, c is the fundamental curvature at the vertex, k is the conic section constant, r is the radial coordinate perpendicular to the optical axis, and a i a is the coefficient of the higher-order term. i r 2i For aspherical surfaces, there are multiple terms.
[0121] The coefficient values of each aspherical surface in the above embodiment 1 are shown in Table 7:
[0122]
[0123]
[0124] Where 1.098E-04 indicates that the coefficient a2 of surface number S1 is 1.098 * 10^6. -4 And so on.
[0125] Figure 10 for Figure 9 The diagram shows the axial aberration curves of a telephoto lens. The vertical direction represents the normalized aperture, with 0 indicating the maximum pupil radius at the vertical vertex on the optical axis. The horizontal direction represents the offset relative to the ideal focus, expressed in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system image, derived from... Figure 10 It can be seen that the axial aberrations of the normalized apertures for different visible light wavelengths from 0 to 1.0 are all controlled within a certain range, indicating that the spherical aberration of the optical system is well controlled at each wavelength.
[0126] Figure 11 for Figure 9The field curvature distortion chart of the long-focus lens is shown in the figure, wherein, in the left coordinate system, the horizontal coordinate represents the size of the field curvature, with unit of mm; the vertical coordinate represents the normalized image height without unit; in the right coordinate system, the horizontal coordinate represents the size of the distortion (F-Tan(Theta)), with unit of %; the vertical coordinate represents the normalized image height without unit. Figure 11 It can be seen that the long-focus lens provided by the embodiment is effectively controlled in the field curvature from light with wavelength of 0.435 μm to light with wavelength of 0.650 μm, that is, the difference between the best imaging planes of the central field of view and the edge field of view is small when imaging; the F-Tan(Theta) distortion of the long-focus lens is within 5%, the imaging distortion is reasonable, and the general requirements are met.
[0127] Figure 12 For Figure 9 The axial chromatic aberration chart of the long-focus lens is shown in the figure, wherein, the vertical direction represents the normalized aperture, 0 represents on the optical axis, and the vertex in the axial direction represents the maximum pupil radius; the main wavelength uses 555 nm, the horizontal direction represents the offset amount relative to the main wavelength, with unit of micrometers (um). From the figure, Figure 12 It can be seen that the axial chromatic aberration of different wavelengths is controlled within a reasonable range, which shows that the axial chromatic aberration of the long-focus lens is well controlled, and the application requirements in the visible light band can be met.
[0128] It should be noted that the above is only a preferred embodiment of the present application and the technical principle applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, re-adjustments, mutual combinations and substitutions without departing from the protection scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and more other equivalent embodiments can be included without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.
Claims
1. A large-aperture telephoto lens with a large focal length, characterized in that, Along the optical axis from the object side to the image side, it includes, in sequence, a first lens with positive optical power, a second lens with positive optical power, a third lens with negative optical power, a fourth lens with negative optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power. The first lens and the sixth lens are glass aspherical lenses, while the remaining lenses are plastic aspherical lenses.
2. The telephoto lens according to claim 1, characterized in that: The object-side surface of the first lens is convex, and the image-side surface is also convex. The second lens has a convex object-side surface and a concave image-side surface; The object side of the third lens is convex, and the image side is concave. The fourth lens has a concave side and a convex side; The object side of the fifth lens is concave, and the image side is also concave. The object side of the sixth lens is convex, and the image side is also convex. The object side of the seventh lens is convex, and the image side is also convex. The object side of the eighth lens is concave, and the image side is also concave.
3. The telephoto lens according to claim 1, characterized in that, Each lens in the telephoto lens satisfies the following condition: in, The optical power of the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are respectively. The optical power of the telephoto lens is given.
4. The telephoto lens according to claim 3, characterized in that, The first lens, the second lens, the fourth lens, and the fifth lens satisfy the following conditions: in, The optical power of the first lens, the second lens, the fourth lens, and the fifth lens are respectively. The optical power of the telephoto lens is given.
5. The telephoto lens according to claim 1, characterized in that, The first lens satisfies the following condition: 1.854≤TTL / ΦL1≤1.924; Wherein, TTL is the total optical length of the telephoto lens, and ΦL1 is the lens diameter of the first lens.
6. The telephoto lens according to claim 1, characterized in that, The eighth lens satisfies the following condition: 1.185≤TTL / ΦL8≤1.206; Wherein, TTL is the total optical length of the telephoto lens, and ΦL8 is the lens diameter of the eighth lens.
7. The telephoto lens according to claim 1, characterized in that, The telephoto lens satisfies the following condition: 14.519≤TTL / BFL≤15.434; Wherein, BFL is the rear focal length of the telephoto lens, and TTL is the total optical length of the telephoto lens.
8. The telephoto lens according to claim 1, characterized in that, The telephoto lens satisfies the following conditions: 3.980 <f6 / CT6<4.280; -10.687 <f8 / CT8<-10.095; Where f6 is the focal length of the sixth lens, f8 is the focal length of the eighth lens, CT6 is the center thickness of the sixth lens, and CT8 is the center thickness of the eighth lens.
9. The telephoto lens according to claim 1, characterized in that, The telephoto lens satisfies the following condition: FNO≤1.397; Wherein, FNO is the aperture number of the telephoto lens.
10. The telephoto lens according to claim 1, characterized in that, It also includes an aperture stop, which is located on the object side of the first lens.