Zoom lens

Abstract

The zoom lens comprises a focusing lens group, a diaphragm and a zoom lens group which are sequentially arranged from an object plane to an image plane along an optical axis, the focusing lens group has negative focal power, the zoom lens group has positive focal power, and the focusing lens group comprises a first lens, a second lens and a third lens, the zoom lens group comprises a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens. The zoom lens group comprises at least one triplet lens group. According to the zoom lens provided by the embodiment of the invention, a two-component structure is adopted, nine lenses are used, the number of the lenses in the two lens groups is set, the focal power matching of the two lens groups and the nine lenses is further limited, and the triplet lens group is used behind the diaphragm, so that the zoom lens has high resolution under the 1 / 2.7 ''target surface and the wave band of 436-850 nm, and the resolution ratio of the zoom lens is greatly improved. And the use requirements of large aperture, high definition, small volume and infrared confocal are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical devices, and in particular to a zoom lens. BACKGROUND

[0002] In recent years, the demand for lenses in the monitoring market is increasingly diversified. In the field of security and protection, zoom lenses have been widely used due to their long shooting distance and large shooting angle. At the same time, with the development of technology, cameras are gradually developing towards miniaturization and refinement, which also puts forward more stringent requirements for zoom lenses as core components. An ideal zoom lens not only needs to have powerful image acquisition function, but also needs to realize large aperture zoom imaging in the full focal range under the condition of meeting high resolution and large target surface.

[0003] At present, in order to realize large aperture to ensure the amount of light, the conventional zoom lens will increase the diameter of the lens barrel, resulting in a large size of the lens. For some scenes with high volume requirements, the above-mentioned lens will be difficult to apply. At the same time, in order to improve the imaging quality of the zoom lens, the proportion of glass lenses will also be increased to a large extent, which is heavy and high in cost. In addition, in the day and night monitoring scene, the conventional zoom lens also has the problem of infrared non-axial focusing, which affects the reliability of monitoring and is difficult to meet the comprehensive needs of modern security monitoring for high-performance, large-aperture, small-size, low-cost, infrared-axial zoom lenses. SUMMARY

[0004] An object of the present application is to solve or at least alleviate part or all of the above problems. To this end, an object of the present application is to provide a zoom lens to realize a large-aperture, high-definition, small-size, infrared-axial zoom lens.

[0005] The present application provides a zoom lens, comprising, in order along an optical axis from an object plane to an image plane, a focusing lens group, a diaphragm and a zoom lens group;

[0006] The focusing lens group and the zoom lens group are movably arranged along the optical axis direction;

[0007] The focusing lens group has negative optical power, and the zoom lens group has positive optical power;

[0008] The focusing lens group comprises, in order from the object plane to the image plane, a first lens, a second lens and a third lens; the first lens has negative optical power, the second lens has negative optical power, and the third lens has positive optical power;

[0009] The variable magnification lens group comprises, in order from the object side to the image side, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens; the fourth lens has positive refractive power, the fifth lens has positive refractive power, the sixth lens has negative refractive power, the seventh lens has positive refractive power, the eighth lens has negative refractive power, and the ninth lens has positive refractive power.

[0010] The variable magnification lens group comprises at least one three-cemented lens group.

[0011] Optionally, the first lens, the fifth lens, the sixth lens and the seventh lens are glass spherical lenses, the second lens, the third lens, the eighth lens and the ninth lens are plastic aspherical lenses, and the fourth lens is a glass aspherical lens.

[0012] Optionally, the focal length of the focusing lens group is FG1, the focal length of the variable magnification lens group is FG2, and the focal length of the zoom lens at the wide-angle end is FW.

[0013] -1.93≤FG1 / FW≤-1.89; 2.33≤FG2 / FW≤2.35.

[0014] Optionally, the focal length of the focusing lens group is FG1, the focal length of the variable magnification lens group is FG2, and the focal length of the zoom lens at the telephoto end is FT.

[0015] -0.81≤FG1 / FT≤-0.80; 0.96≤FG2 / FT≤1.01.

[0016] Optionally, the maximum movable distance of the focusing lens group is S1, the maximum movable distance of the variable magnification lens group is S2, and 1.81≤S2 / S1≤1.85.

[0017] Optionally, the fifth lens, the sixth lens and the seventh lens form the three-cemented lens group.

[0018] Optionally, the combined focal length of the fifth lens, the sixth lens and the seventh lens is F567, the focal length of the variable magnification lens group is FG2, and 3.84≤F567 / FG2≤3.96.

[0019] The refractive index of the third lens is nd3, and the Abbe number of the third lens is vd3.

[0020] The refractive index of the fourth lens is nd4, and the Abbe number of the fourth lens is vd4.

[0021] The refractive index of the fifth lens is nd5, and the Abbe number of the fifth lens is vd5.

[0022] The refractive index of the seventh lens is nd7, and the Abbe number of the seventh lens is vd7;

[0023] 1.640≤nd3≤1.671; 19.276≤vd3≤23.503;

[0024] 1.437≤nd4≤1.497; 81.605≤vd4≤94.439;

[0025] 1.437≤nd5≤1.550; 75.496≤vd5≤95.109;

[0026] 1.437≤nd7≤1.550; 75.496≤vd7≤95.100.

[0027] Optionally, the focal length of the zoom lens at the wide-angle end is FW, and the focal length of the zoom lens at the telephoto end is FT;

[0028] 2.33≤FT / FW≤2.42.

[0029] Optionally, the total optical length of the zoom lens at the wide-angle end is TTL, and the maximum movable distance of the zoom lens group is S2; 5.91≤TTL / S2≤6.32.

[0030] The zoom lens provided by the embodiment of the present application adopts a two-group element structure, uses nine lenses, sets the number of lenses in the two lens groups, and further limits the focal power matching of the two lens groups and the nine lenses, so that the zoom lens meets the requirements of large aperture, high definition, small size, and infrared confocal use under the condition of 1 / 2.7″ target surface and in the wavelength range of 436nm to 850nm.

[0031] 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 application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0033] Figure 1 A structural schematic diagram of a zoom lens provided by the embodiment of the present application at the wide-angle end;

[0034] Figure 2 A structure schematic view of a zoom lens at a long focal end provided by an embodiment of the present application;

[0035] Figure 3 A structure schematic view of another zoom lens at a wide angle end provided by an embodiment of the present application;

[0036] Figure 4 A structure schematic view of another zoom lens at a long focal end provided by an embodiment of the present application;

[0037] Figure 5 A structure schematic view of another zoom lens at a wide angle end provided by an embodiment of the present application;

[0038] Figure 6 A structure schematic view of another zoom lens at a long focal end provided by an embodiment of the present application;

[0039] Figure 7 A vertical axis chromatic aberration curve of the zoom lens at a wide angle end provided by the embodiment one of the present application;

[0040] Figure 8 A vertical axis chromatic aberration curve of the zoom lens at a long focal end provided by the embodiment one of the present application;

[0041] Figure 9 An axial aberration curve of the zoom lens at a wide angle end provided by the embodiment one of the present application;

[0042] Figure 10 An axial aberration curve of the zoom lens at a long focal end provided by the embodiment one of the present application;

[0043] Figure 11 A ray fan diagram of the zoom lens at a wide angle end provided by the embodiment one of the present application;

[0044] Figure 12 A ray fan diagram of the zoom lens at a long focal end provided by the embodiment one of the present application;

[0045] Figure 13 A vertical axis chromatic aberration curve of the zoom lens at a wide angle end provided by the embodiment two of the present application;

[0046] Figure 14 A vertical axis chromatic aberration curve of the zoom lens at a long focal end provided by the embodiment two of the present application;

[0047] Figure 15 An axial aberration curve of the zoom lens at a wide angle end provided by the embodiment two of the present application;

[0048] Figure 16 An axial aberration curve of the zoom lens at a long focal end provided by the embodiment two of the present application;

[0049] Figure 17 This is a ray fan diagram of the zoom lens at the wide-angle end provided in Embodiment 2 of the present invention;

[0050] Figure 18 This is a ray fan pattern of the zoom lens at the telephoto end provided in Embodiment 2 of the present invention;

[0051] Figure 19 This is a diagram showing the lateral chromatic aberration curve of a zoom lens at the wide-angle end, as provided in Embodiment 3 of the present invention.

[0052] Figure 20 This is a chromatic aberration curve of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention;

[0053] Figure 21 This is an axial aberration curve of the zoom lens at the wide-angle end provided in Embodiment 3 of the present invention;

[0054] Figure 22 This is an axial aberration curve of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention;

[0055] Figure 23 This is a ray fan diagram of the zoom lens at the wide-angle end provided in Embodiment 3 of the present invention;

[0056] Figure 24 This is a light fan pattern of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention. Detailed Implementation

[0057] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0058] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0059] Figure 1 This is a schematic diagram of the structure of a zoom lens at the wide-angle end according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a zoom lens at the telephoto end, provided by an embodiment of the present invention; Figure 3 This is a schematic diagram of another zoom lens at the wide-angle end provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of another zoom lens at the telephoto end provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of another zoom lens at the wide-angle end provided in an embodiment of the present invention. Figure 6 This is a schematic diagram of the structure of another zoom lens at the telephoto end provided in an embodiment of the present invention; as shown. Figures 1-6 As shown, the zoom lens provided in this embodiment of the invention includes a focusing lens group G1, an aperture stop STO, and a zoom lens group G2 arranged sequentially along the optical axis from the object plane to the image plane. The focusing lens group G1 and the zoom lens group G2 are movable along the optical axis. The focusing lens group G1 has negative optical power, and the zoom lens group G2 has positive optical power. The focusing lens group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged sequentially from the object plane to the image plane. The first lens L1 has negative optical power, the second lens L2 has negative optical power, and the third lens L3 has positive optical power. The zoom lens group G2 includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9 arranged sequentially from the object plane to the image plane. The fourth lens L4 has positive optical power, the fifth lens L5 has positive optical power, the sixth lens L6 has negative optical power, the seventh lens L7 has positive optical power, the eighth lens L8 has negative optical power, and the ninth lens L9 has positive optical power. The zoom lens group G2 also includes at least one cemented triplet lens group g1.

[0060] Specifically, the focusing lens group G1 and the zoom lens group G2 can be housed in a single lens barrel (not shown in the figure), but this is not a limitation.

[0061] In this invention, the aperture stop STO is fixed in position within the lens barrel, ensuring that it remains stationary relative to the image plane. This embodiment employs a fixed aperture design, with the STO positioned between the third lens L3 and the fourth lens L4. This design, by placing a negative optical power focusing lens group G1 at the front of the STO, causes incident light to diverge before passing through the STO, thus creating a larger effective light-gathering aperture at the STO. This achieves a large aperture of f / 1.3 at the wide-angle end and f / 2.5 at the telephoto end without increasing the physical diameter of the lens barrel, significantly improving the lens's light-gathering capability and meeting usage requirements under various conditions. Simultaneously, the fixed aperture design simplifies the structure, facilitating overall lens miniaturization.

[0062] The focusing lens group G1 and the zoom lens group G2 can reciprocate along the optical axis within the lens barrel. Moving the focusing lens group G1 enables focusing, while the zoom lens group G2, with its overall positive optical power, undertakes the lens's main light-gathering and zoom functions. By changing the relative positions of the focusing lens group G1 and the zoom lens group G2 on the optical axis, continuous zoom from the wide-angle end to the telephoto end can be achieved, meeting the shooting needs of different scenarios. It can be understood that during the zoom process, the lens is at the wide-angle end when the focal length is shortest and at the telephoto end when the focal length is longest; at the wide-angle and telephoto ends, the zoom lens has different focal lengths and optical powers.

[0063] Furthermore, optical power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam; it characterizes the ability of an optical system to deflect light rays. The larger the absolute value of the optical power, the stronger the bending ability of light rays; the smaller the absolute value, the weaker the bending ability. When the optical power is positive, the refraction of light rays is converging; when the optical power is negative, the refraction of light rays 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).

[0064] In embodiments of the present invention, such as Figures 1-6 As shown, the focusing lens group G1 consists of a first lens L1, a second lens L2, and a third lens L3. The negative optical power of the first lens L1 helps to diverge incident light, providing a larger effective aperture for the subsequent aperture stop (STO). The second lens L2 works in conjunction with the first lens L1 to further control the degree of light divergence; its negative optical power effectively corrects the large field-of-view aberrations unique to wide-angle lenses, helping to ensure image sharpness and edge sharpness at the wide-angle end. The positive optical power of the third lens L3 acts to converge light, forming a negative-negative-positive optical power combination with the first lens L1 and the second lens L2. This combination effectively balances and corrects the aberrations introduced by the first lens L1 and the second lens L2.

[0065] The zoom lens group G2 consists of a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9. The fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8, and ninth lens L9 employ a positive-positive-negative-positive-negative-positive optical power combination. Through the alternating arrangement of positive and negative lenses, a reasonable distribution and balance of optical power is achieved within the zoom lens group G2. This helps control the propagation of light within the zoom lens group G2, reduces aberrations caused by excessive concentration of optical power, and makes the image quality more stable throughout the zoom process.

[0066] Furthermore, such as Figures 1-6As shown, the zoom lens group G2 includes at least one cemented triplet lens group g1, which is a composite lens assembly formed by tightly bonding three independent lens elements together with optical adhesive. In this embodiment of the invention, the cemented triplet lens group g1 is located in the middle and rear section of the optical path, which can effectively correct residual aberrations introduced by the front lens, significantly improve the image sharpness and uniformity in the edge areas of the image, and ensure high resolution across the entire field of view. At the same time, in conjunction with the focusing lens group G1 in front of the aperture stop STO, various aberrations can be continuously corrected during continuous zooming, effectively avoiding drastic fluctuations in image quality caused by changes in focal length, and enabling the lens to maintain stable image quality across the entire focal length range.

[0067] Furthermore, a cemented triplet lens group g1 is employed after the STO aperture. This g1 group combines a positive-power lens with a negative-power lens using a specific material combination. By utilizing the dispersive properties of different optical materials, it achieves chromatic aberration complementarity, powerfully correcting axial chromatic aberration in visible and near-infrared light. This allows the lens to achieve clear imaging across the entire 436nm to 850nm wavelength range, achieving infrared confocal focusing and ensuring continuous clarity of day and night monitoring images without the need for refocusing. Simultaneously, as a single optical unit, the g1 group has no internal air interfaces, allowing it to control its own residual chromatic aberration to an extremely low level. It also uses residual chromatic aberration to balance and compensate for chromatic aberration introduced by the STO aperture-front focusing lens group G1 and other optical components during zooming. This ensures that various aberrations in the zoom lens are fully corrected, improving imaging performance.

[0068] Using a cemented lens group g1 behind the STO aperture can significantly reduce the air gap between the lenses, helping to compress the overall optical length and achieve lens miniaturization and compact structure. At the same time, it can also improve resolution, optimize optical performance such as distortion, and reduce light loss caused by reflections between lenses, thereby improving illumination, thus improving image quality and enhancing the sharpness of the lens image.

[0069] Understandably, after light passes through the STO aperture, the use of the cemented triplet lens group g1 effectively corrects chromatic aberration, preventing its accumulation at the rear of the lens. This avoids the need for rear-end optical components to use large amounts of high Abbe number, high-cost optical materials to compensate for residual chromatic aberration. Furthermore, it effectively reduces chromatic aberration, achieving confocal imaging in both the visible and near-infrared bands with clear image quality. Simultaneously, using a single cemented triplet lens group g1 within the zoom lens group G2 allows for extreme chromatic aberration correction, eliminating purple and green fringing and ensuring accurate color reproduction.

[0070] In summary, the zoom lens provided in this embodiment of the invention adopts a two-element structure and uses nine lenses. By setting the number of lenses in the two lens groups and further limiting the optical power matching of the two lens groups and the nine lenses, and using a triplex lens group behind the aperture stop, the zoom lens meets the requirements of large aperture, high definition, small size, and infrared confocal focus at a 1 / 2.7″ target surface and in the 436nm to 850nm wavelength range.

[0071] As one possible implementation method, please refer to [reference]. Figures 1-6 The object-side surface of the first lens L1 is convex, and the image-side surface is concave; the object-side surface of the second lens L2 is concave, and the image-side surface is concave; the object-side surface of the third lens L3 is convex, and the image-side surface is convex; the object-side surface of the fourth lens L4 is convex, and the image-side surface is convex; the object-side surface of the fifth lens L5 is convex, and the image-side surface is either concave or convex; the object-side surface of the sixth lens L6 is either convex or concave, and the image-side surface is concave; the object-side surface of the seventh lens L7 is convex, and the image-side surface is convex; the object-side surface of the eighth lens L8 is concave, and the image-side surface is convex; the object-side surface of the ninth lens L9 is convex, and the image-side surface is concave.

[0072] The shape of the lens affects the direction of light propagation, determining how light bends when passing through the lens, which in turn affects the lens's maximum aperture and light transmission, as well as the image quality and characteristics.

[0073] In this embodiment, by rationally matching the surface shapes of each lens, while meeting the optical power requirements of each lens and achieving the required optical performance indicators (such as large aperture, high resolution, small size, and infrared confocal focus), it is beneficial to further reduce the overall optical length of the zoom lens, thereby achieving a miniaturized lens design. Furthermore, while ensuring a large aperture, it also makes the light path smoother as it passes through the entire zoom lens, reducing unnecessary reflections and absorption, which helps improve light transmission and image quality.

[0074] As one feasible implementation, the first lens L1, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are glass spherical lenses, the second lens L2, the third lens L3, the eighth lens L8 and the ninth lens L9 are plastic aspherical lenses, and the fourth lens L4 is a glass aspherical lens.

[0075] Among them, the second lens L2 and the third lens L3 in the focusing lens group G1 use aspherical lenses, which can effectively correct distortion and spherical aberration at the wide-angle end, ensuring the geometric accuracy of the image and the high definition of the central area under the wide-angle field of view.

[0076] The fourth lens L4 (glass aspherical), the eighth lens L8, and the ninth lens L9 (plastic aspherical) in the zoom lens group G2 work together to correct spherical aberration and astigmatism at the telephoto end, ensuring image sharpness at the edges and uniformity across the entire field of view.

[0077] Among them, aspherical lenses have a good ability to control higher aberrations of the lens. The use of an aspherical lens for the fourth lens L4 can further reduce higher aberrations after light passes through the aperture stop STO, thereby improving the image quality of the lens.

[0078] Furthermore, glass lenses are not sensitive to temperature. The fourth lens, L4, uses a glass aspherical lens, which allows for more consistent lens performance under different temperature conditions, exhibiting stable performance at both high and low temperatures. The introduction of glass aspherical lenses also significantly corrects chromatic aberration and advanced aberrations. Compared to plastic aspherical lenses, there is a wider range of optical materials to choose from, providing greater freedom in optical design, enabling more diverse structural solutions, and enhancing the lens's market competitiveness.

[0079] The zoom lens utilizes a total of five aspherical lenses in its focusing lens group G1 and zoom lens group G2. This greatly enhances the lens's ability to control aberrations, allowing for full and dynamic correction of various aberrations throughout the entire zoom range, from wide-angle to telephoto. This results in excellent resolution, contrast, and sharpness across the entire field of view and focal length, from the center to the edge of the image, and from wide-angle to telephoto.

[0080] Understandably, using more aspherical lenses can reduce the total number of lenses required for the entire lens while maintaining performance. Every time light passes through a lens, it undergoes weak reflection and scattering, leading to glare, ghosting, and decreased contrast. Therefore, reducing the total number of lenses can reduce the likelihood of these harmful effects and improve the clarity and overall contrast of the image.

[0081] Furthermore, the eighth lens L8 and the ninth lens L9 at the end of the zoom lens group G2, through their aspherical design, can not only effectively eliminate advanced aberrations, but also improve the overall image quality while expanding the imaging target size supported by the lens. This allows the zoom lens to be adapted to higher resolution image sensors and meet the usage requirements in more situations.

[0082] Furthermore, the second lens L2, the third lens L3, the eighth lens L8, and the ninth lens L9 are made of plastic lenses, which can reduce lens costs and lighten lens weight.

[0083] The first lens L1, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are spherical lenses made of glass, which can achieve higher transmittance, reduce light energy loss, and improve imaging performance in low-light environments. At the same time, glass lenses have the advantages of high hardness, strong wear resistance, long service life, and are not easily deformed by temperature, which makes the zoom lens performance more stable.

[0084] Among them, the combination of glass lenses and plastic lenses can also utilize the mutual compensation effect of these two materials. By using glass lenses or plastic lenses at specific positions, the resolution of the lens can be better balanced.

[0085] As a feasible implementation method, the aperture number of the zoom lens at the wide-angle end is FNO1, and the aperture number of the zoom lens at the telephoto end is FNO2; FNO1≤1.30; FNO2≤2.50.

[0086] The zoom lens provided in this embodiment of the invention can achieve a super-large aperture of F1.3 at the wide-angle end and a large aperture of F2.5 at the telephoto end, ensuring that the lens has good light-gathering ability throughout the entire zoom range. Even at the telephoto end, it can collect sufficient light, improving the imaging performance of the lens in low-light environments (such as at night or in dimly lit indoor scenes), and meeting the requirements of security monitoring for all-weather high-definition imaging.

[0087] Furthermore, zoom lenses maintain a fixed aperture throughout the zoom process, simplifying the lens's mechanical structure and drive system. This avoids the complexity and potential failure points associated with variable aperture mechanisms, improving the lens's reliability and durability. Simultaneously, a fixed aperture provides greater stability during zooming, resulting in smoother changes in image brightness and contributing to a more seamless transition in the captured image.

[0088] As a feasible implementation, the focal length of the focusing lens group G1 is FG1, the focal length of the zoom lens group G2 is FG2, and the focal length of the zoom lens at the wide-angle end is FW; -1.93≤FG1 / FW≤-1.89; 2.33≤FG2 / FW≤2.35.

[0089] By limiting the ratio of the optical power of the focusing lens group G1 and the zoom lens group G2 to the wide-angle focal length FW of the zoom lens, a reasonable combination of optical power is achieved, allowing light to pass through the lens more smoothly. This effectively controls the incident angle and refraction angle of light on each lens surface, avoiding drastic light deflection caused by excessive or insufficient optical power. This not only reduces the aberration increment caused by large-angle incident light but also reduces reflection and scattering losses on the lens surface, improving light energy utilization and image clarity, and is beneficial for correcting the impact of advanced aberrations on image quality.

[0090] As a feasible implementation, the focal length of the focusing lens group G1 is FG1, the focal length of the zoom lens group G2 is FG2, and the focal length of the zoom lens at the telephoto end is FT; -0.81≤FG1 / FT≤-0.80; 0.96≤FG2 / FT≤1.01.

[0091] Specifically, by limiting the ratio of the optical power of the focusing lens group G1 and the zoom lens group G2 to the focal length FT at the telephoto end of the zoom lens, a reasonable combination of optical power is achieved, allowing light to pass through the lens more smoothly. This effectively controls the angle of incidence and angle of refraction of light on each lens surface, avoiding drastic light deflection caused by excessive or insufficient optical power. It also effectively controls the problem of large-angle incident light at the telephoto end, reduces the generation of advanced aberrations, and helps to correct the impact of advanced aberrations on image quality, allowing the light beam to converge on the image plane in the best possible state.

[0092] It should be noted that the aforementioned ratio of the optical power of the focusing lens group G1 and the zoom lens group G2 to the focal length FT at the telephoto end of the zoom lens works in conjunction with the ratio of the optical power of the focusing lens group G1 and the zoom lens group G2 to the focal length FW at the wide-angle end of the zoom lens. This ensures stable performance across the entire focal length range, guaranteeing a smooth and continuous transition in the distribution of optical power and the correction of aberrations throughout the zoom process from the wide-angle end to the telephoto end. This results in high-resolution, high-contrast, and high-stability imaging across the entire focal length range and throughout the entire process.

[0093] As a feasible implementation, the maximum movable distance of the focusing lens group G1 is S1, and the maximum movable distance of the zoom lens group G2 is S2; 1.81≤S2 / S1≤1.85.

[0094] The maximum movable distance along the optical axis of the focusing lens group G1 during zooming is S1, and the maximum movable distance along the optical axis of the zoom lens group G2 during zooming is S2. By controlling the movable distances of the focusing lens group G1 and the zoom lens group G2, the volume and range of motion of the focusing lens group G1 can be significantly reduced, which is beneficial to reducing the size of the lens.

[0095] As one feasible implementation, the fifth lens L5, the sixth lens L6, and the seventh lens L7 form a cemented triplet lens group g1.

[0096] Among them, the fifth lens L5, the sixth lens L6 and the seventh lens L7 can be glued together with optical glue to form a three-layer glued lens group g1.

[0097] The triple-cemented lens group g1 is positioned after the aperture stop STO. By cementing the positive power lens (fifth lens L5 and seventh lens L7) with the negative power lens (sixth lens L6), the chromatic aberration can be complemented by utilizing the dispersion characteristics of different optical materials. The chromatic aberration generated by the positive and negative lenses cancels each other out, which can effectively reduce the generation of chromatic aberration. In particular, it can strongly correct the focus shift between visible light (such as 436nm) and near-infrared light (such as 850nm), ensuring that the lens can achieve clear imaging in the entire spectral range and realize infrared confocal imaging.

[0098] Meanwhile, the triplet lens group g1 not only has extremely small chromatic aberration, but the residual chromatic aberration it produces can also be used to actively balance and compensate for the chromatic aberration introduced by the focusing lens group G1 at the front of the aperture stop and other optical components during zooming. This allows all kinds of aberrations to be fully corrected throughout the entire zoom lens and the entire field of view. Under the premise of compact structure, it can improve resolution, optimize optical performance such as distortion, and comprehensively improve image quality.

[0099] The triplet lens group g1 cements three lenses together into a single unit, which reduces the number of reflections and scatterings of light between the lenses, reduces the loss of light flux, and improves the overall illumination of the lens, thereby improving image quality and enhancing the sharpness of the lens image.

[0100] Furthermore, the triplet lens group g1 compresses the spacing between the fifth lens L5, the sixth lens L6, and the seventh lens L7 to zero, effectively reducing the air gap between the fifth lens L5, the sixth lens L6, and the seventh lens L7, and shortening the physical length of the zoom lens group G2. Thus, while ensuring optical performance, the total optical length (TTL) of the entire lens is significantly reduced.

[0101] As a feasible implementation, the combined focal length of the fifth lens L5, the sixth lens L6 and the seventh lens L7 is F567, and the focal length of the zoom lens group G2 is FG2; 3.84≤F567 / FG2≤3.96.

[0102] Specifically, by limiting the ratio of the combined focal length F567 of the fifth lens L5, the sixth lens L6, and the seventh lens L7 to the focal length FG2 of the zoom lens group G2 within the range of 3.84 to 3.96, the fifth lens L5, the sixth lens L6, and the seventh lens L7 can effectively exert their chromatic aberration compensation capabilities, and the residual chromatic aberration they produce can effectively balance the chromatic aberration of other parts of the system, thereby achieving global optimization of the chromatic aberration of the entire lens and avoiding over- or under-correction.

[0103] Furthermore, under the aforementioned proportional constraints, the sensitivity to manufacturing tolerances (such as center thickness, spacing, and surface shape error) of the fifth lens L5, the sixth lens L6, and the seventh lens L7 is relatively low. Even with minor processing errors in mass production, the overall imaging performance of the lens can remain stable, which helps to improve the yield and consistency of the lens.

[0104] As a feasible implementation, the refractive index of the third lens L3 is nd3, and the Abbe number of the third lens L3 is vd3; the refractive index of the fourth lens L4 is nd4, and the Abbe number of the fourth lens L4 is vd4; the refractive index of the fifth lens L5 is nd5, and the Abbe number of the fifth lens L5 is vd5; the refractive index of the seventh lens L7 is nd7, and the Abbe number of the seventh lens L7 is vd7; 1.640≤nd3≤1.671; 19.276≤vd3≤23.503; 1.437≤nd4≤1.497; 81.605≤vd4≤94.439; 1.437≤nd5≤1.550; 75.496≤vd5≤95.109; 1.437≤nd7≤1.550; 75.496≤vd7≤95.100.

[0105] The refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium. It is mainly used to describe a material's ability to refract light, and different materials have different refractive indices.

[0106] The Abbe number is an index used to represent the dispersion ability of a transparent medium. The more severe the dispersion of the medium, the smaller the Abbe number; conversely, the less severe the dispersion of the medium, the larger the Abbe number.

[0107] In this embodiment, by reasonably limiting the refractive index and Abbe number of the third lens L3, the fourth lens L4, the fifth lens L5 and the seventh lens L7, spherical aberration and higher-order aberrations can be corrected to a greater extent, which is beneficial to eliminating distortion in the telephoto end image and maintaining the geometric shape of the image.

[0108] In this embodiment of the invention, the correction of chromatic aberration and advanced aberrations of the zoom lens mainly relies on the triplet lens group g1 and the aspherical lens. Therefore, the selection of materials for the third lens L3 located in front of the aperture stop STO, the fourth lens L4 located behind the aperture stop STO, and the fifth lens L5 and the seventh lens L7 of the triplet lens group g1 are crucial.

[0109] In this embodiment, introducing aspherical lenses before and after the aperture stop STO can effectively improve the chromatic aberration of the light passing through the aperture stop STO. At the same time, the fourth lens L4, which has a high Abbe number, also plays an effective role in correcting the chromatic aberration of the light after the aperture stop STO.

[0110] The fifth lens L5 and the seventh lens L7 of the triplex lens group g1 are made of high Abbe number material, which can correct chromatic aberration and advanced aberrations generated at the rear of the lens.

[0111] As a feasible implementation method, the focal length of the zoom lens at the wide-angle end is FW, and the focal length of the zoom lens at the telephoto end is FT; 2.33≤FT / FW≤2.42.

[0112] By controlling the focal length ratio between the wide-angle and telephoto ends of the lens, the zoom range and focal length range of the lens can be controlled. This allows for more effective correction of various aberrations generated during the entire zoom process from the wide-angle end to the telephoto end, and can meet the usage needs under more conditions.

[0113] As a feasible implementation method, the total optical length of the zoom lens at the wide-angle end is TTL, and the maximum movable distance of the zoom lens group G2 is S2; 5.91≤TTL / S2≤6.32.

[0114] The total length TTL of the zoom lens refers to the distance from the center of the optical axis on the object side of the first lens L1 at the wide-angle end of the zoom lens to the image plane (the TTL at the wide-angle end is the longest during the zoom stroke of the zoom lens).

[0115] In this embodiment, by limiting the ratio between the total optical length TTL and the maximum movable distance S2 of the zoom lens group G2, the lens space can be compressed, and the miniaturization and weight reduction of the lens can be achieved while meeting the requirements of imaging quality and zoom level.

[0116] As a possible implementation method, such as Figures 1-6 As shown, the zoom lens may also include a flat glass CG, which is located on the image side of the ninth lens L9. The flat glass CG can be used to protect the photosensitive chip in the imaging sensor, which is used to convert the light signals collected by the zoom lens into electrical signals, thereby ensuring the imaging effect of the zoom optical system.

[0117] In some cases, flat glass CG can also be used to correct specific aberrations or filter out unwanted light, but this embodiment of the invention does not specifically limit this.

[0118] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the zoom lens applicable to the above-described embodiments.

[0119] Example 1

[0120] like Figure 1 and Figure 2 As shown, the zoom lens provided in Embodiment 1 of the present invention includes a focusing lens group G1, an aperture stop STO, and a zoom lens group G2 arranged sequentially along the optical axis from the object plane to the image plane.

[0121] The focusing lens group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged sequentially from the object plane to the image plane. The zoom lens group G2 includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9 arranged sequentially from the object plane to the image plane.

[0122] The flat glass CG is located on the image side of the ninth lens L9.

[0123] Table 1 details the specific optical physical parameters of each lens in the zoom lens provided in Embodiment 1 of the present invention at infinity object distance, according to a feasible implementation method. The zoom lens in Table 1 corresponds to... Figure 1 and Figure 2 The zoom lens shown.

[0124] Table 1 Design values ​​of optical physical parameters for zoom lenses

[0125]

[0126] The surface numbers in Table 1 are assigned according to the surface sequence of each lens, where "1" represents the object side of the first lens, "2" represents the image side of the first lens, and so on; "STO" represents the aperture stop of the lens; IMA represents the image plane; the radius of curvature represents the 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, where "INF" 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 material (nd) is the refractive index, representing the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the material (vd) is the Abbe number, representing the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air.

[0127] Table 2 shows the zoom interval values ​​for the zoom lens at the wide-angle and telephoto ends in Table 1.

[0128] Table 2 Design values ​​for zoom interval of zoom lenses

[0129]

[0130] In Table 2, the zoom intervals are the different interval values ​​for the zoom lens at the wide-angle end and the telephoto end.

[0131] In this embodiment, the aspherical lens of the zoom lens can satisfy the following formula:

[0132] ;

[0133] Where Z is the axial distance from the vertex of the surface at a position perpendicular to the optical axis and at a height of r along the optical axis; c represents the curvature at the vertex of the aspherical surface; To fit the conic coefficients; , , , , , and These are the higher-order aspheric coefficients corresponding to the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders of aspheric surfaces. These can be combined to form higher-order terms for the corresponding aspherical surfaces.

[0134] For example, Table 3 details the aspherical coefficients of each lens in this embodiment one by way of a feasible implementation.

[0135] Table 3 Design values ​​of aspherical coefficients for various lenses in zoom lenses

[0136]

[0137] The zoom lens in this embodiment can achieve the following technical specifications:

[0138] Table 4 Technical Specifications of Zoom Lenses

[0139]

[0140] Figure 7 This is a chromatic aberration curve of the zoom lens at the wide-angle end provided in Embodiment 1 of the present invention. Figure 8 This is a chromatic aberration curve of the zoom lens at the telephoto end provided in Embodiment 1 of the present invention. The vertical direction represents the normalization of the field of view, 0 represents the optical axis, and the vertex of the vertical direction represents the maximum field of view. The dominant wavelength is 546.07nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 7 and Figure 8 The maximum field of view is 3.3050 mm. (By...) Figure 7 and Figure 8 It can be seen that the chromatic aberration along the vertical axis is controlled within a small range for different wavelengths, indicating that the zoom lens has achieved good control of the chromatic aberration along the vertical axis at both the wide-angle and telephoto ends, which can meet the application requirements under normal conditions.

[0141] Figure 9 This is an axial aberration curve of the zoom lens at the wide-angle end provided in Embodiment 1 of the present invention. Figure 10The image shows the axial aberration curve of the zoom lens at the telephoto end provided in Embodiment 1 of the present invention. The vertical direction represents the normalization of the aperture, 0 represents the optical axis, the vertex of the vertical axis represents the maximum pupil radius, the dominant wavelength is 546.07nm, and the horizontal direction represents the offset relative to the image plane, in millimeters (mm). Figure 9 The radius of the intermediate pupil is 1.2845 mm. Figure 10 The radius of the intermediate pupil is 1.5986 mm. Figure 9 and Figure 10 It can be seen that the axial aberrations of different wavelengths (0.3–1.0 normalized aperture) are all controlled within a reasonable range, indicating that the axial aberrations of this zoom optical system are well controlled at both the wide-angle and telephoto ends, meeting the usage requirements. Furthermore, at pupil positions of 0.5–0.9, there is no significant chromatic aberration between visible and infrared light, meeting the basic requirement of clear imaging at night and achieving clear imaging across the entire wavelength range.

[0142] Figure 11 This is the ray fan pattern of the zoom lens at the wide-angle end provided in Embodiment 1 of the present invention. Figure 12 This is a ray fan plot of a zoom lens at the telephoto end, provided in Embodiment 1 of the present invention. The ray fan plot is a commonly used evaluation method by optical designers. In a single plot, the horizontal axis represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should completely coincide with the horizontal axis, at which point all rays in the field of view are focused at the same point on the image plane. The vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The ray fan plot can reflect not only monochromatic aberrations at different wavelengths but also the magnitude of transverse chromatic aberration. Figure 11 and Figure 12 It can be seen that this zoom lens closely approximates the horizontal axis at all wavelengths in both the wide-angle and telephoto ends, indicating that the transverse aberrations of each wavelength are well corrected. Furthermore, the curves for each color do not show significant dispersion, indicating that this zoom lens also provides good correction for chromatic aberration, meeting the requirements for zoom lens use.

[0143] Example 2

[0144] like Figure 3 and Figure 4 As shown, the zoom lens provided in Embodiment 2 of the present invention includes a focusing lens group G1, an aperture stop STO, and a zoom lens group G2 arranged sequentially along the optical axis from the object plane to the image plane.

[0145] The focusing lens group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged sequentially from the object plane to the image plane. The zoom lens group G2 includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9 arranged sequentially from the object plane to the image plane.

[0146] The flat glass CG is located on the image side of the ninth lens L9.

[0147] Table 5 details the specific optical physical parameters of each lens in the zoom lens provided in Embodiment 2 of the present invention at infinity object distance, according to a feasible implementation method. The zoom lens in Table 5 corresponds to... Figure 3 and Figure 4 The zoom lens shown.

[0148] Table 5 Design values ​​of optical physical parameters for zoom lenses

[0149]

[0150] The surface numbers in Table 5 are assigned according to the surface sequence of each lens, where "1" represents the object side of the first lens, "2" represents the image side of the first lens, and so on; "STO" represents the aperture stop of the lens; IMA represents the image plane; the radius of curvature represents the 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, where "INF" 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 material (nd) is the refractive index, representing the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the material (vd) is the Abbe number, representing the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air.

[0151] Table 6 shows the zoom interval values ​​for the zoom lens at the wide-angle and telephoto ends in Table 5.

[0152] Table 6 Design values ​​for zoom interval of zoom lenses

[0153]

[0154] In Table 6, the zoom intervals are the different interval values ​​for the zoom lens at the wide-angle end and the telephoto end.

[0155] In this embodiment, the aspherical lens of the zoom lens can satisfy the following formula:

[0156] ;

[0157] Where Z is the axial distance from the vertex of the surface at a position perpendicular to the optical axis and at a height of r along the optical axis; c represents the curvature at the vertex of the aspherical surface; To fit the conic coefficients; , , , , , and These are the higher-order aspheric coefficients corresponding to the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders of aspheric surfaces. These can be combined to form higher-order terms for the corresponding aspherical surfaces.

[0158] For example, Table 7 details the aspherical coefficients of each lens in this second embodiment with a feasible implementation.

[0159] Table 7 Design values ​​of aspherical coefficients for various lenses in zoom lenses

[0160]

[0161] The zoom lens in this second embodiment can achieve the following technical specifications:

[0162] Table 8 Technical Specifications of Zoom Lenses

[0163]

[0164] Figure 13 This is a chromatic aberration curve of the zoom lens at the wide-angle end provided in Embodiment 2 of the present invention. Figure 14 This is a chromatic aberration curve of the zoom lens at the telephoto end provided in Embodiment 2 of the present invention. The vertical direction represents the normalization of the field of view, 0 represents the optical axis, and the vertex of the vertical direction represents the maximum field of view. The dominant wavelength is 546.07nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 13 and Figure 14 The maximum field of view is 3.3050 mm. (By...) Figure 13 and Figure 14 It can be seen that the chromatic aberration along the vertical axis is controlled within a small range for different wavelengths, indicating that the zoom lens has achieved good control of the chromatic aberration along the vertical axis at both the wide-angle and telephoto ends, which can meet the application requirements under normal conditions.

[0165] Figure 15 This is an axial aberration curve of the zoom lens at the wide-angle end provided in Embodiment 2 of the present invention. Figure 16 This is an axial aberration curve of the zoom lens at the telephoto end provided in Embodiment 2 of the present invention. The vertical direction represents the normalization of the aperture, 0 represents the optical axis, the vertex of the vertical axis represents the maximum pupil radius, the dominant wavelength is 546.07nm, and the horizontal direction represents the offset relative to the image plane, in millimeters (mm). Figure 15 The radius of the intermediate pupil is 1.2611 mm. Figure 16 The radius of the intermediate pupil is 1.5516 mm. Figure 15 and Figure 16It can be seen that the axial aberrations of different wavelengths (0.3–1.0 normalized aperture) are all controlled within a reasonable range, indicating that the axial aberrations of this zoom optical system are well controlled at both the wide-angle and telephoto ends, meeting the usage requirements. Furthermore, at pupil positions of 0.5–0.9, there is no significant chromatic aberration between visible and infrared light, meeting the basic requirement of clear imaging at night and achieving clear imaging across the entire wavelength range.

[0166] Figure 17 This is the ray fan pattern of the zoom lens at the wide-angle end provided in Embodiment 2 of the present invention. Figure 18 This is a ray fan plot of a zoom lens at the telephoto end provided in Embodiment 2 of the present invention. The ray fan plot is one of the commonly used evaluation methods by optical designers. In a single plot, the horizontal axis represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should completely coincide with the horizontal axis, at which point all rays in the field of view are focused at the same point on the image plane. The vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The ray fan plot can not only reflect monochromatic aberrations of different wavelengths but also the magnitude of transverse chromatic aberration. Figure 17 and Figure 18 It can be seen that this zoom lens closely approximates the horizontal axis at all wavelengths in both the wide-angle and telephoto ends, indicating that the transverse aberrations of each wavelength are well corrected. Furthermore, the curves for each color do not show significant dispersion, indicating that this zoom lens also provides good correction for chromatic aberration, meeting the requirements for zoom lens use.

[0167] Example 3

[0168] like Figure 5 and Figure 6 As shown, the zoom lens provided in Embodiment 3 of the present invention includes a focusing lens group G1, an aperture stop STO, and a zoom lens group G2 arranged sequentially along the optical axis from the object plane to the image plane.

[0169] The focusing lens group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged sequentially from the object plane to the image plane. The zoom lens group G2 includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9 arranged sequentially from the object plane to the image plane.

[0170] The flat glass CG is located on the image side of the ninth lens L9.

[0171] Table 9 details the specific optical physical parameters of each lens in the zoom lens provided in Embodiment 3 of the present invention at infinity object distance, according to a feasible implementation method. The zoom lens in Table 9 corresponds to... Figure 5 and Figure 6 The zoom lens shown.

[0172] Table 9 Design values ​​of optical physical parameters for zoom lenses

[0173]

[0174] The surface numbers in Table 9 are assigned according to the surface order of each lens, where "1" represents the object side of the first lens, "2" represents the image side of the first lens, and so on; "STO" represents the aperture stop of the lens; IMA represents the image plane; the radius of curvature represents the 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, where "INF" 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 material (nd) is the refractive index, representing the ability of the material between the current surface and the next surface to deflect light, with a blank space indicating that the current position is air and the refractive index is 1; the material (vd) is the Abbe number, representing the dispersion characteristics of the material between the current surface and the next surface, with a blank space indicating that the current position is air.

[0175] Table 10 shows the zoom interval values ​​for the zoom lens at the wide-angle and telephoto ends in Table 9.

[0176] Table 10 Design values ​​for zoom interval of zoom lenses

[0177]

[0178] In Table 10, the zoom intervals are the different interval values ​​of the zoom lens at the wide-angle end and the telephoto end.

[0179] In this embodiment, the aspherical lens of the zoom lens can satisfy the following formula:

[0180] ;

[0181] Where Z is the axial distance from the vertex of the surface at a position perpendicular to the optical axis and at a height of r along the optical axis; c represents the curvature at the vertex of the aspherical surface; To fit the conic coefficients; , , , , , and These are the higher-order aspheric coefficients corresponding to the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders of aspheric surfaces. These can be combined to form higher-order terms for the corresponding aspherical surfaces.

[0182] For example, Table 11 details the aspherical coefficients of each lens in this embodiment three according to a feasible implementation.

[0183] Table 11 Design values ​​of aspherical coefficients for various lenses in zoom lenses

[0184]

[0185] The zoom lens in this third embodiment can achieve the following technical specifications:

[0186] Table 12 Technical Specifications of Zoom Lenses

[0187]

[0188] Figure 19 This is a chromatic aberration curve of the zoom lens at the wide-angle end provided in Embodiment 3 of the present invention. Figure 20 This is a chromatic aberration curve of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention. The vertical direction represents the normalization of the field of view, 0 represents the optical axis, and the vertex of the vertical direction represents the maximum field of view. The dominant wavelength is 546.07nm, and the horizontal direction represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 19 and Figure 20 The maximum field of view is 3.3050 mm. (By...) Figure 19 and Figure 20 It can be seen that the chromatic aberration along the vertical axis is controlled within a small range for different wavelengths, indicating that the zoom lens has achieved good control of the chromatic aberration along the vertical axis at both the wide-angle and telephoto ends, which can meet the application requirements under normal conditions.

[0189] Figure 21 This is an axial aberration curve of the zoom lens at the wide-angle end provided in Embodiment 3 of the present invention. Figure 22 This is an axial aberration curve of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention. The vertical direction represents the normalization of the aperture, 0 represents the optical axis, the vertex of the vertical axis represents the maximum pupil radius, the dominant wavelength is 546.07nm, and the horizontal direction represents the offset relative to the image plane, in millimeters (mm). Figure 21 The radius of the intermediate pupil is 1.2663 mm. Figure 22 The radius of the intermediate pupil is 1.5563 mm. Figure 21 and Figure 22 It can be seen that the axial aberrations of different wavelengths (0.3–1.0 normalized aperture) are all controlled within a reasonable range, indicating that the axial aberrations of this zoom optical system are well controlled at both the wide-angle and telephoto ends, meeting the usage requirements. Furthermore, at pupil positions of 0.5–0.9, there is no significant chromatic aberration between visible and infrared light, meeting the basic requirement of clear imaging at night and achieving clear imaging across the entire wavelength range.

[0190] Figure 23 This is the ray fan pattern of the zoom lens at the wide-angle end provided in Embodiment 3 of the present invention. Figure 24This is a ray fan plot of a zoom lens at the telephoto end provided in Embodiment 3 of the present invention. The ray fan plot is one of the commonly used evaluation methods by optical designers. In a single plot, the horizontal axis represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should completely coincide with the horizontal axis, at which point all rays in the field of view are focused at the same point on the image plane. The vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The ray fan plot can not only reflect monochromatic aberrations at different wavelengths but also the magnitude of transverse chromatic aberration. Figure 23 and Figure 24 It can be seen that this zoom lens closely approximates the horizontal axis at all wavelengths in both the wide-angle and telephoto ends, indicating that the transverse aberrations of each wavelength are well corrected. Furthermore, the curves for each color do not show significant dispersion, indicating that this zoom lens also provides good correction for chromatic aberration, meeting the requirements for zoom lens use.

[0191] To provide a clearer explanation of the above embodiments, Table 13 details the specific optical physical parameters of each lens in the zoom lens provided in Embodiments 1 to 3 of the present invention.

[0192] Table 13 Design values ​​of optical physical parameters for zoom lenses

[0193]

[0194] The specific embodiments described above do not constitute a limitation on the scope of protection of this 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 principles of this invention should be included within the scope of protection of this invention.

Claims

1. A zoom lens, characterized in that, It includes a focusing lens group, an aperture stop, and a zoom lens group arranged sequentially along the optical axis from the object plane to the image plane; The focusing lens group and the zoom lens group are movable along the optical axis; The focusing lens group has negative optical power, and the zoom lens group has positive optical power; The focusing lens group includes a first lens, a second lens, and a third lens arranged sequentially from the object plane to the image plane; the first lens has negative optical power, the second lens has negative optical power, and the third lens has positive optical power; The zoom lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially from the object plane to the image plane; the fourth lens has positive optical power, the fifth lens has positive optical power, the sixth lens has negative optical power, the seventh lens has positive optical power, the eighth lens has negative optical power, and the ninth lens has positive optical power. The zoom lens group includes at least one cemented triplet lens group.

2. The zoom lens according to claim 1, characterized in that, The first lens, the fifth lens, the sixth lens, and the seventh lens are glass spherical lenses; the second lens, the third lens, the eighth lens, and the ninth lens are plastic aspherical lenses; and the fourth lens is a glass aspherical lens.

3. The zoom lens according to claim 1, characterized in that, The focal length of the focusing lens group is FG1, the focal length of the zoom lens group is FG2, and the focal length of the zoom lens at the wide-angle end is FW; -1.93≤FG1 / FW≤-1.89; 2.33≤FG2 / FW≤2.

35.

4. The zoom lens according to claim 1, characterized in that, The focal length of the focusing lens group is FG1, the focal length of the zoom lens group is FG2, and the focal length of the zoom lens at the telephoto end is FT; -0.81≤FG1 / FT≤-0.80; 0.96≤FG2 / FT≤1.

01.

5. The zoom lens according to claim 1, characterized in that, The maximum movable distance of the focusing lens group is S1, and the maximum movable distance of the zoom lens group is S2; 1.81≤S2 / S1≤1.

85.

6. The zoom lens according to claim 1, characterized in that, The fifth lens, the sixth lens, and the seventh lens constitute the cemented triplet lens group.

7. The zoom lens according to claim 1, characterized in that, The combined focal length of the fifth lens, the sixth lens, and the seventh lens is F567, and the focal length of the zoom lens group is FG2; 3.84≤F567 / FG2≤3.

96.

8. The zoom lens according to claim 1, characterized in that, The refractive index of the third lens is nd3, and the Abbe number of the third lens is vd3; the refractive index of the fourth lens is nd4, and the Abbe number of the fourth lens is vd4; the refractive index of the fifth lens is nd5, and the Abbe number of the fifth lens is vd5; the refractive index of the seventh lens is nd7, and the Abbe number of the seventh lens is vd7; 1.640≤nd3≤1.671; 19.276≤vd3≤23.503; 1.437≤nd4≤1.497; 81.605≤vd4≤94.439; 1.437≤nd5≤1.550; 75.496≤vd5≤95.109; 1.437≤nd7≤1.550; 75.496≤vd7≤95.

100.

9. The zoom lens according to claim 1, characterized in that, The zoom lens has a focal length of FW at the wide-angle end and a focal length of FT at the telephoto end; 2.33≤FT / FW≤2.

42.

10. The zoom lens according to claim 1, characterized in that, The total optical length of the zoom lens at the wide-angle end is TTL, and the maximum movable distance of the zoom lens group is S2; 5.91≤TTL / S2≤6.32.

Images