A zoom lens

Abstract

The application discloses a zoom lens, comprising, along an optical axis, a focusing lens group, a zoom lens group and a fixed lens group arranged in sequence from an object plane to an image plane, the focusing lens group having negative refractive power, the zoom lens group having positive refractive power, and the fixed lens group having positive refractive power, the focusing lens group comprising, from the object plane to the image plane, a first lens, a second lens, a third lens and a fourth lens arranged in sequence, the zoom lens group comprising, from the object plane to the image plane, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens and an eleventh lens arranged in sequence, and the fixed lens group comprising a twelfth lens. The zoom lens provided by the embodiment of the application adopts a three-group-element architecture to cooperate with precise arrangement of 12 lenses, the number of lenses in the three lens groups is set, and the refractive power of the three lens groups and the 12 lenses is further limited, so that a zoom lens with a large target surface, a large aperture, a high zoom ratio, high image quality, a small size and infrared confocal is realized.

Description

Technical Field

[0001] This invention relates to the field of optical device technology, and more particularly to a zoom lens. Background Technology

[0002] With the rapid development of security monitoring technology, zoom lenses, due to their advantages of both long-distance shooting and wide-angle coverage, are widely used in various security monitoring systems. At the same time, camera equipment is evolving towards miniaturization and high integration, which places more stringent requirements on zoom lenses, namely, achieving a smaller size while ensuring high image quality.

[0003] As technology iterates, the size of image sensors is constantly being upgraded. Currently, 1 / 1.2-inch (1 / 1.2″) sensors are gradually becoming the mainstream choice in the security field due to their good balance in pixel size, photosensitive area, and system integration, with increasingly wider application scenarios. However, traditional zoom lenses are still mainly adapted to smaller target surfaces such as 1 / 2.7-inch (1 / 2.7″), making it difficult to fully utilize the high-resolution advantage of the large target surface of 1 / 1.2″ sensors, thus limiting the overall improvement of image quality. In addition, traditional zoom lenses generally have problems such as large aperture values ​​(F-numbers) and non-confocal infrared, resulting in insufficient light intake in low-light environments, affecting image brightness and signal-to-noise ratio, and restricting their applicability in complex lighting conditions in all weather conditions. Summary of the Invention

[0004] One object of the present invention is to solve or at least alleviate some or all of the above-mentioned problems. To this end, one object of the present invention is to provide a zoom lens that achieves a large sensor size, large aperture, small size, infrared confocal focus, and high image quality compatible with a 1 / 1.2″ sensor.

[0005] This invention provides a zoom lens, comprising a focusing lens group, a zoom lens group, and a fixed lens group arranged sequentially along the optical axis from the object plane to the image plane;

[0006] The fixed lens group is fixedly installed, while the focusing lens group and the zoom lens group are movable along the optical axis.

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

[0008] The focusing lens group includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object plane to the image plane;

[0009] The zoom lens group includes a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged sequentially from the object plane to the image plane;

[0010] The fixed lens group includes a twelfth lens;

[0011] The first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has negative optical power;

[0012] 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, the ninth lens has positive optical power, the tenth lens has negative optical power, and the eleventh lens has negative optical power.

[0013] The twelfth lens has positive optical power.

[0014] Optionally, the sixth lens and the seventh lens form a first cemented lens group;

[0015] The eighth lens and the ninth lens together form the second cemented lens group.

[0016] Optionally, the first cemented lens group has positive optical power;

[0017] The second cemented lens group has positive optical power.

[0018] Optionally, the focal length of the first cemented lens group is F67, the focal length of the second cemented lens group is F89, and the focal length of the zoom lens group is F2q; 1.572≤F67 / F2q≤1.996, 3.660≤F89 / F2q≤5.201.

[0019] Optionally, the second lens, the fifth lens, the tenth lens, and the eleventh lens are all aspherical lenses;

[0020] The first lens, the third lens, the fourth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, and the twelfth lens are all spherical lenses.

[0021] Optionally, the zoom lens further includes an aperture stop located in the optical path between the focusing lens group and the zoom lens group.

[0022] Optionally, the object-side surface of the first lens is convex, and the image-side surface of the first lens is concave.

[0023] The object-side surface of the second lens is convex, and the image-side surface of the second lens is concave.

[0024] The object-side surface of the third lens is convex, and the image-side surface of the third lens is concave.

[0025] The object-side surface of the fourth lens is concave, and the image-side surface of the fourth lens is convex.

[0026] The object-side surface of the fifth lens is convex, and the image-side surface of the fifth lens is convex.

[0027] The object-side surface of the sixth lens is convex, and the image-side surface of the sixth lens is concave.

[0028] The object-side surface of the seventh lens is convex, and the image-side surface of the seventh lens is convex.

[0029] The object-side surface of the eighth lens is concave, and the image-side surface of the eighth lens is also concave.

[0030] The object-side surface of the ninth lens is convex, and the image-side surface of the ninth lens is convex.

[0031] The object-side surface of the tenth lens is convex, and the image-side surface of the tenth lens is concave.

[0032] The object-side surface of the eleventh lens is concave, and the optical axis region of the image-side surface of the eleventh lens is concave.

[0033] The object-side surface of the twelfth lens is convex, and the image-side surface of the twelfth lens is also convex.

[0034] Optionally, the focal length of the focusing lens group is F1q, the focal length of the zoom lens group is F2q, the focal length of the fixed lens group is F3q, and the focal length of the zoom lens at the wide-angle end is FW; -2.548≤F1q / FW≤-2.370; 0.985≤F2q / FW≤1.024; 1.365≤F3q / FW≤1.467.

[0035] Optionally, the total length of the zoom lens is TTL, and the maximum movable distance of the zoom lens group is ZOOM; 3.52≤TTL / ZOOM≤3.78.

[0036] Optionally, the refractive index of the second lens is nd2, and the Abbe number of the second lens is vd2; the refractive index of the fifth lens is nd5, and the Abbe number of the fifth lens is vd5; the refractive index of the tenth lens is nd10, and the Abbe number of the tenth lens is vd10; the refractive index of the eleventh lens is nd11, and the Abbe number of the eleventh lens is vd11; 1.439≤nd2≤1.555; 71.483≤vd2≤94.437; 1.439≤nd5≤1.555; 71.483≤vd5≤94.437; 1.856≤nd10≤1.888; 37.185≤vd10≤40.068; 1.518≤nd11≤1.595; 63.989≤vd11≤70.274.

[0037] Optionally, the refractive index of the first lens is nd1, and the Abbe number of the first lens is vd1; the refractive index of the seventh lens is nd7, and the Abbe number of the seventh lens is vd7; the refractive index of the ninth lens is nd9, and the Abbe number of the ninth lens is vd9; 1.961≤nd1≤2.060; 25.425≤vd1≤32.312; 1.438≤nd7≤1.498; 81.607≤vd7≤95.099; 2.000≤nd9≤2.012; 25.425≤vd9≤28.892.

[0038] Optionally, the refractive index of the twelfth lens is nd12, and the Abbe number of the twelfth lens is vd12; 1.878≤nd12≤2.039; 23.574≤vd12≤28.316.

[0039] The zoom lens provided in this embodiment of the invention adopts a three-element architecture with a precise arrangement of 12 lenses. By setting the number of lenses in the three lens groups and further limiting the optical power matching of the three lens groups and 12 lenses, it meets high-performance indicators such as a large target area of ​​1 / 1.2″, a large aperture, 3.2x optical zoom, full-band confocal focal length from 436nm to 870nm, and high image quality, while keeping the total length of the lens within a compact range (e.g., ≤65.05mm). It achieves a balance between a large target area, a large aperture, a high zoom ratio, high image quality, small size, and infrared confocal focal length, and can also achieve good image quality at close range, which can meet the usage needs of security monitoring, intelligent vision, and many other applications.

[0040] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] 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;

[0043] 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;

[0044] Figure 3 This is a schematic diagram of another zoom lens at the wide-angle end provided in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of another zoom lens at the telephoto end provided in an embodiment of the present invention;

[0046] 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;

[0047] 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;

[0048] Figure 7 The modulation transfer function curve of the zoom lens provided in Embodiment 1 of the present invention at infinity object distance at the wide-angle end in the visible light band;

[0049] Figure 8 The modulation transfer function curve of the zoom lens provided in Embodiment 1 of the present invention at a wide-angle end with an object distance of 1.5 meters in the visible light band.

[0050] Figure 9 This is the defocus modulation transfer function curve of the zoom lens provided in Embodiment 1 of the present invention at infinity object distance in the near-infrared band at the wide-angle end;

[0051] Figure 10 The modulation transfer function curve of the zoom lens provided in Embodiment 1 of the present invention at infinity object distance at the telephoto end in the visible light band.

[0052] Figure 11 The modulation transfer function curve of the zoom lens provided in Embodiment 1 of the present invention at a telephoto end of 3 meters in the visible light band;

[0053] Figure 12 The defocus modulation transfer function curve of the zoom lens provided in Embodiment 1 of the present invention at infinity object distance at the telephoto end in the near-infrared band.

[0054] Figure 13 This is the modulation transfer function curve of the zoom lens provided in Embodiment 2 of the present invention at infinity object distance at the wide-angle end in the visible light band.

[0055] Figure 14 The modulation transfer function curve of the zoom lens provided in Embodiment 2 of the present invention at a wide-angle end with an object distance of 1.5 meters in the visible light band.

[0056] Figure 15 This is the defocus modulation transfer function curve of the zoom lens provided in Embodiment 2 of the present invention at infinity object distance in the near-infrared band at the wide-angle end;

[0057] Figure 16 The modulation transfer function curve of the zoom lens provided in Embodiment 2 of the present invention at infinity object distance at the telephoto end in the visible light band.

[0058] Figure 17 The modulation transfer function curve of the zoom lens provided in Embodiment 2 of the present invention at a distance of 3 meters at the telephoto end in the visible light band;

[0059] Figure 18 This is the defocus modulation transfer function curve of the zoom lens provided in Embodiment 2 of the present invention at infinity object distance in the near-infrared band;

[0060] Figure 19 The modulation transfer function curve of the zoom lens provided in Embodiment 3 of the present invention at infinity object distance at the wide-angle end in the visible light band;

[0061] Figure 20 The modulation transfer function curve of the zoom lens provided in Embodiment 3 of the present invention at a wide-angle end with an object distance of 1.5 meters in the visible light band.

[0062] Figure 21 This is the defocus modulation transfer function curve of the zoom lens provided in Embodiment 3 of the present invention at infinity object distance in the near-infrared band at the wide-angle end;

[0063] Figure 22 The modulation transfer function curve of the zoom lens provided in Embodiment 3 of the present invention at infinity object distance at the telephoto end in the visible light band;

[0064] Figure 23 The modulation transfer function curve of the zoom lens provided in Embodiment 3 of the present invention at a distance of 3 meters at the telephoto end in the visible light band;

[0065] Figure 24 The defocus modulation transfer function curve of the zoom lens provided in Embodiment 3 of the present invention at infinity object distance in the near-infrared band. Detailed Implementation

[0066] 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.

[0067] 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.

[0068] 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 as an embodiment of the present invention.

[0069] like Figures 1-6 As shown, the zoom lens provided in this embodiment of the invention includes a focusing lens group G1, a zoom lens group G2, and a fixed lens group G3 arranged sequentially along the optical axis from the object plane to the image plane.

[0070] The fixed lens group G3 is fixedly set, while the focusing lens group G1 and the zoom lens group G2 are moved along the optical axis.

[0071] The focusing lens group G1 has negative optical power, the zoom lens group G2 has positive optical power, and the fixed lens group G3 has positive optical power.

[0072] The focusing lens group G1 includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged sequentially from the object plane to the image plane.

[0073] The zoom lens group G2 includes the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11, arranged sequentially from the object plane to the image plane.

[0074] The fixed lens group G3 includes the twelfth lens L12.

[0075] The first lens L1 has positive optical power, the second lens L2 has negative optical power, the third lens L3 has positive optical power, and the fourth lens L4 has negative optical power.

[0076] 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, the ninth lens L9 has positive optical power, the tenth lens L10 has negative optical power, and the eleventh lens L11 has negative optical power.

[0077] The twelfth lens, L12, has positive optical power.

[0078] Specifically, the focusing lens group G1, the zoom lens group G2, and the fixed lens group G3 can be housed in a single lens barrel (not shown in the figure), but this is not the only option.

[0079] The focusing lens group G1 and the zoom lens group G2 can reciprocate along the optical axis in the lens barrel to achieve focusing and zoom functions respectively. 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 to meet the shooting needs in different scenarios.

[0080] It is understandable that in the process of zooming, the shortest focal length is at the wide-angle end and the longest focal length is at the telephoto end. At the wide-angle end and the telephoto end, the zoom lens has different focal lengths and optical powers.

[0081] The fixed lens group G3 is fixed in position in the lens barrel, so that the fixed lens group G3 does not move relative to the image plane. The fixed lens group G3 is used to converge light rays and finally form an image on the image plane.

[0082] 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).

[0083] In this embodiment, the focusing lens group G1 has a negative optical power, which can effectively reduce the height of the incident light and the angle of the principal ray. Especially at the wide-angle end, it can significantly compress the incident tilt of the edge field of view light, which is beneficial to suppress distortion and vignetting under large target surfaces (such as 1 / 1.2″) and provide the lens with a greater degree of freedom in adjusting the entrance pupil position, making it easier to achieve a large aperture design.

[0084] The zoom lens group G2 has positive optical power as a whole. By changing its spacing with the front and rear lens groups as it moves along the optical axis, it can achieve continuous focal length changes from the wide-angle end to the telephoto end (the zoom ratio can reach 3.2X).

[0085] The fixed lens group G3 has positive optical power and serves to converge the beam and stabilize the image plane. Because its position is fixed, it can accurately compensate for residual field curvature and higher-order aberrations throughout the zoom stroke, while maintaining the image plane position basically unchanged (i.e., achieving good parfocal performance). This avoids the need for additional compensation groups, which helps to simplify the mechanical structure and shorten the overall length.

[0086] The aforementioned "negative-positive-positive" optical power allocation scheme can effectively control the lens size and improve the imaging consistency across the entire field of view and wide band (such as 436nm to 870nm) while ensuring high zoom ratio, large target area coverage and large aperture performance. It is suitable for security monitoring application scenarios with high requirements for miniaturization, high image quality and environmental adaptability.

[0087] Furthermore, the focusing lens group G1 consists of four lenses, arranged sequentially from the object plane to the image plane: first lens L1, second lens L2, third lens L3, and fourth lens L4. The first lens L1, second lens L2, third lens L3, and fourth lens L4 employ a "positive-negative-positive-negative" optical power combination. This combination not only achieves clear imaging of close-range objects but also effectively corrects aberrations caused by large-angle incident light, contributing to improved edge imaging quality on the 1 / 1.2″ large target surface.

[0088] The zoom lens group G2 consists of seven lenses, arranged sequentially from the object plane to the image plane: lens L5 (fifth), lens L6 (sixth), lens L7 (seventh), lens L8 (eighth), lens L9 (ninth), lens L10 (tenth), and lens L11 (eleventh). Lenses L5 through L11 employ a "positive-negative-positive-negative-positive-negative-negative" optical power combination. This multi-lens alternating positive and negative optical structure achieves a smooth 3.2x zoom within a limited travel distance. Simultaneously, it effectively suppresses aberration fluctuations during zooming, ensuring stable image quality across the entire zoom range and contributing to good confocal performance across a wide wavelength range (e.g., 436nm to 870nm).

[0089] The fixed lens group G3 contains only one twelfth lens L12. The twelfth lens L12 has positive optical power, which can converge light to the image plane and perform final correction of lens aberrations to ensure sharp imaging.

[0090] In summary, the zoom lens provided in this embodiment of the invention adopts a three-element architecture with a precise arrangement of 12 lenses. By setting the number of lenses in the three lens groups and further limiting the optical power combination of the three lens groups and the 12 lenses, it meets high-performance indicators such as a large target area of ​​1 / 1.2″, a large aperture, 3.2x optical zoom, full-band confocal focal length from 436nm to 870nm, and high image quality, while keeping the total length of the lens within a compact range (e.g., ≤65.05mm). This achieves a balance between a large target area, a large aperture, a high zoom ratio, high image quality, small size, and infrared confocal focal length, and also achieves good image quality at close range, meeting the usage needs of security monitoring, intelligent vision, and many other applications.

[0091] As a possible implementation method, such as Figures 1-6 As shown, the sixth lens L6 and the seventh lens L7 form the first cemented lens group g1, and the eighth lens L8 and the ninth lens L9 form the second cemented lens group g2.

[0092] Specifically, such as Figures 1-6 As shown, in the zoom lens group G2, the sixth lens L6 with negative optical power and the seventh lens L7 with positive optical power are cemented together to form the first cemented lens group g1; the eighth lens L8 with negative optical power and the ninth lens L9 with positive optical power are cemented together to form the second cemented lens group g2. By cementing multiple lenses, aberrations at the rear of the lens can be corrected within a limited space, especially effectively suppressing chromatic aberration, spherical aberration, and astigmatism generated during zooming. This significantly reduces the aberration correction burden on other lens groups (such as the focusing lens group G1 and the fixed lens group G3) at different focal lengths. Combined with the aberration control of the lens group before the aperture stop STO, this ensures stable and excellent image quality throughout the entire zoom range.

[0093] As a possible implementation method, such as Figures 1-6 As shown, the first cemented lens group g1 has positive optical power; the second cemented lens group g2 has positive optical power.

[0094] By adopting a structural design of a double positive optical power cemented lens group, a reasonable distribution of optical power and coordinated aberration correction are achieved in the zoom lens group G2. This is beneficial to maintaining the stability of the lens image quality during zooming, especially in the wide band (436nm-870nm) range, effectively suppressing chromatic aberration and improving infrared confocal performance, which helps to meet the dual requirements of high-resolution imaging and small size design.

[0095] As a possible implementation method, such as Figures 1-6As shown, the focal length of the first cemented lens group g1 is F67, the focal length of the second cemented lens group g2 is F89, and the focal length of the zoom lens group G2 is F2q; 1.572≤F67 / F2q≤1.996, 3.660≤F89 / F2q≤5.201.

[0096] By controlling the ratio of the focal length of the first cemented lens group g1 and the second cemented lens group g2 to the focal length of the zoom lens group G2 within the aforementioned range, the optical power distribution of each lens group can be effectively coordinated during zooming. This allows for the correction of chromatic aberration and higher aberrations within the zoom lens group G2. This configuration not only facilitates stable infrared confocal performance across the entire 436nm-870nm wavelength range but also significantly reduces the aberration compensation pressure on other lens groups at different focal lengths, ensuring high image quality across the entire focal range while meeting the requirements of a compact structure and small size.

[0097] As a possible implementation method, such as Figures 1-6 As shown, the second lens L2, the fifth lens L5, the tenth lens L10 and the eleventh lens L11 are all aspherical lenses; the first lens L1, the third lens L3, the fourth lens L4, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9 and the twelfth lens L12 are all spherical lenses.

[0098] Among them, aspherical lenses have a high degree of freedom in surface shape and possess excellent advanced aberration correction capabilities.

[0099] In this embodiment, by arranging aspherical lenses at key locations, such as the second lens L2 in the focusing lens group G1, and the fifth lens L5, tenth lens L10, and eleventh lens L11 in the zoom lens group G2, higher-order aberrations when light enters the image plane can be further reduced, significantly improving the imaging quality of the edge field of view and meeting the imaging requirements of 4K and even higher resolution sensors. Simultaneously, in conjunction with aberration control of the lens group before the aperture stop STO, stable and excellent imaging quality can be ensured throughout the entire zoom range.

[0100] Furthermore, during zooming, the zoom lens group G2 plays a crucial role in changing the lens's focal length. By strategically arranging aspherical lenses (such as the fifth lens L5, the tenth lens L10, and the eleventh lens L11) within this group, chromatic aberration, spherical aberration, and other advanced aberrations caused by zooming can be effectively compensated. This design significantly reduces the aberration correction burden on the remaining lens groups (such as the focusing lens group G1 and the fixed lens group G3) at different focal lengths, thereby ensuring that the lens can achieve clear and stable focusing and imaging across the entire focal length range.

[0101] Furthermore, the first lens L1, the third lens L3, the fourth lens L4, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, and the twelfth lens L12 are all spherical lenses. Their processing technology is mature and the cost is controllable. They can effectively correct the basic aberrations of the lens and work in conjunction with the aforementioned aspherical lenses to achieve all-round correction and balance of aberrations.

[0102] As a possible implementation method, such as Figures 1-6 As shown, the zoom lens also includes an aperture stop STO, which is located in the optical path between the focusing lens group G1 and the zoom lens group G2.

[0103] Specifically, such as Figures 1-6 As shown, the aperture stop STO is located in front of the fifth lens L5, which has positive optical power.

[0104] In this embodiment, the aperture stop STO is mechanically linked to the zoom lens group G2 and moves along the optical axis together with the zoom lens group G2. Therefore, the position of the aperture stop STO relative to the zoom lens group G2 remains constant throughout the zoom process. This helps to maintain the stability of the lens pupil position at different focal lengths, thereby ensuring the consistency of aberration characteristics and illumination uniformity during zooming and improving imaging stability.

[0105] In terms of optical configuration, in front of the aperture STO is the focusing lens group G1 with negative optical power, and immediately behind it is the fifth lens L5 with positive optical power. This gives the light passing through the aperture STO a larger beam diameter, thereby effectively reducing the lens's F number (increasing the aperture) and increasing the amount of light transmitted. This allows the lens to maintain good image brightness and signal-to-noise ratio even in low light conditions, meeting the usage needs of all-weather, multi-light environments in scenarios such as security monitoring.

[0106] In this embodiment, by reasonably controlling the aperture of the stop STO and its linkage mechanism with the zoom lens group G2, the lens can maintain a large effective light-gathering aperture at different focal lengths, thereby achieving a large aperture at both the wide-angle and telephoto ends. Specifically, the lens's F-number FNOW at the wide-angle end can meet FNOW=1.7, and the F-number FNOT at the telephoto end can meet FNOT=3.2, ensuring that the lens can still obtain sufficient light in low-light environments, significantly improving low-light imaging performance and visibility range, and meeting the usage requirements under various lighting conditions such as security monitoring and night shooting.

[0107] As a possible implementation method, such as Figures 1-6As shown, the object-side surface of the first lens L1 is convex, and the image-side surface of the first lens L1 is concave; the object-side surface of the second lens L2 is convex, and the image-side surface of the second lens L2 is concave; the object-side surface of the third lens L3 is convex, and the image-side surface of the third lens L3 is concave; the object-side surface of the fourth lens L4 is concave, and the image-side surface of the fourth lens L4 is convex; the object-side surface of the fifth lens L5 is convex, and the image-side surface of the fifth lens L5 is convex; the object-side surface of the sixth lens L6 is convex, and the image-side surface of the sixth lens L6 is concave; the seventh lens L7... The object-side surface of the seventh lens L7 is convex, and the image-side surface of the eighth lens L8 is concave; the object-side surface of the ninth lens L9 is convex, and the image-side surface of the ninth lens L9 is convex; the object-side surface of the tenth lens L10 is convex, and the image-side surface of the tenth lens L10 is concave; the object-side surface of the eleventh lens L11 is concave, and the optical axis region of the image-side surface of the eleventh lens L11 is concave; the object-side surface of the twelfth lens L12 is convex, and the image-side surface of the twelfth lens L12 is convex.

[0108] The object-side or image-side surface of a lens can be divided into different regions depending on its location, including the optical axis region and the peripheral region. The optical axis region refers to the central area of ​​the lens surface near the optical axis, usually corresponding to the paraxial region of the lens. The angle of incidence of light in this region is small, and it is mainly used to control the basic correction of aberrations and the formation of the main imaging optical path. The peripheral region refers to the peripheral area of ​​the lens surface away from the optical axis, usually corresponding to the area where light rays pass through the edge of the lens's large field of view or large aperture. The surface morphology of this region has a significant impact on aberrations such as astigmatism, field curvature, and distortion.

[0109] The size of the optical axis region and the edge region can be defined according to actual needs. For example, the optical axis region refers to the area on the lens surface that is no more than 50% of the maximum effective half-aperture of the surface (i.e., the radius of the intersection of the light rays corresponding to the entrance pupil or the maximum field of view of the lens on the surface). This region mainly affects paraxial rays and small field of view imaging performance, and plays a dominant role in low-order aberrations such as spherical aberration and axial chromatic aberration. The edge region refers to the annular area on the lens surface that is more than 50% of the maximum effective half-aperture of the surface, up to 100% of the maximum effective half-aperture. This region mainly affects off-axis rays incident at large angles and has a significant regulating effect on high-order aberrations such as coma, astigmatism, distortion, and vignetting, but it is not limited to this.

[0110] The maximum effective half-aperture can be determined based on the actual incident height of the principal ray or edge field ray on the lens surface under the most demanding conditions at the wide-angle end, telephoto end, or intermediate focal length. It is usually the maximum value among the three.

[0111] The above-mentioned area definition can be understood in conjunction with the curvature change trend of the lens surface. If the surface curvature shows different signs near the optical axis and near the edge (such as changing from convex to concave or from concave to convex), then the surface has a mixed curvature. For example, the image side of the eleventh lens L11 is concave in the optical axis region and convex in the circumferential region. The mixed curvature surface type adopted by the eleventh lens L11 (the curvature of the optical axis region and the edge region are opposite) can optimize the aberration correction and image surface flatness of the edge field of view, which helps to further balance the aberration distribution under different fields of view and improve the full-frame imaging quality.

[0112] Furthermore, the shape of the lens affects the direction of light propagation, determining how light bends as it passes through the lens, which in turn affects the lens's maximum aperture and light transmission, as well as the quality and characteristics of the image.

[0113] In this embodiment, by rationally matching the surface shapes of each lens, while meeting the optical power requirements of each lens and achieving the necessary optical performance indicators (such as large target surface, large aperture, high zoom ratio, high image quality, small size, and infrared confocality), 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.

[0114] As a possible implementation method, such as Figures 1-6 As shown, the focal length of the focusing lens group G1 is F1q, the focal length of the zoom lens group G2 is F2q, the focal length of the fixed lens group G3 is F3q, and the focal length of the zoom lens at the wide-angle end is FW; -2.548≤F1q / FW≤-2.370; 0.985≤F2q / FW≤1.024; 1.365≤F3q / FW≤1.467.

[0115] By controlling the ratio of the focal length of each lens group to the focal length at the wide-angle end of the lens within the aforementioned range, a reasonable distribution of optical power can be achieved, making the propagation of light in the lens smoother. The coordinated work of each lens group can effectively suppress the accumulation of advanced aberrations (such as spherical aberration, coma, astigmatism, etc.), thereby maintaining excellent imaging quality across the entire focal length range while achieving high zoom ratio, large aperture and large target surface adaptation.

[0116] As a possible implementation method, such as Figures 1-6 As shown, the total length of the zoom lens is TTL, and the maximum movable distance of the zoom lens group G2 is ZOOM; 3.52≤TTL / ZOOM≤3.78.

[0117] 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).

[0118] The maximum movable distance refers to the maximum physical displacement of the lens group along the optical axis from one extreme position (such as the closest focusing position or the wide-angle end position) to another extreme position (such as the infinity focusing position or the telephoto end position) when the lens is working normally. This distance is usually expressed as a linear distance (in millimeters) along the optical axis, without taking into account assembly tolerances and mechanical clearances.

[0119] Specifically, the maximum movable distance ZOOM of the zoom lens group G2 refers to the maximum travel distance of the zoom lens group G2 along the optical axis during the zoom process from the wide-angle end to the telephoto end (or vice versa).

[0120] In this embodiment, by controlling the TTL / ZOOM within the aforementioned range, the space utilization of the zoom lens group G2 can be significantly improved while ensuring zoom range and imaging performance, thereby effectively compressing the overall length of the lens and achieving a compact structure. Specifically, a smaller TTL / ZOOM value means that the zoom lens group G2 has more room to move within the same overall length, which is beneficial for achieving a higher zoom ratio and good image quality. By reasonably controlling this ratio, the overall length of the lens and zoom capability can be balanced, ultimately achieving a miniaturized design with an overall length of only about 62mm to 65mm within the 3.2x zoom range, meeting the requirements of security and other fields for lightweight and highly integrated lenses.

[0121] As a possible implementation method, such as Figures 1-6 As shown, the refractive index of the second lens L2 is nd2, and the Abbe number of the second lens L2 is vd2; 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 tenth lens L10 is nd10, and the Abbe number of the tenth lens L10 is vd10; the refractive index of the eleventh lens L11 is nd11, and the Abbe number of the eleventh lens L11 is vd11; 1.439≤nd2≤1.555; 71.483≤vd2≤94.437; 1.439≤nd5≤1.555; 71.483≤vd5≤94.437; 1.856≤nd10≤1.888; 37.185≤vd10≤40.068; 1.518≤nd11≤1.595; 63.989≤vd11≤70.274.

[0122] 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.

[0123] 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.

[0124] In this embodiment, in order to ensure that the zoom lens can achieve stable imaging across the entire focal length, independent chromatic aberration correction and aberration control are performed on each lens group.

[0125] Specifically, the second lens L2 uses the aforementioned refractive index and Abbe number to effectively control the residual aberrations and chromatic aberrations carried in the light entering the focusing lens group G1, preventing these aberrations from being excessively amplified and difficult to correct during subsequent zoom movements, thus improving the image quality stability during the zoom process.

[0126] Meanwhile, the second lens L2 and the fifth lens L5 use high Abbe number glass aspherical lenses, which can effectively suppress chromatic aberration and control chromatic aberration and spherical aberration at a low level before light enters the zoom lens group G2, so as to avoid excessive aberration accumulation and difficulty in correction during subsequent zooming and focusing.

[0127] In the zoom lens group G2, the fifth lens L5, the tenth lens L10, and the eleventh lens L11 use the above-mentioned refractive index and Abbe number to correct the chromatic aberration and aberration produced by the entire lens in the zoom lens group G2. They control the light within a reasonable range before it enters the image plane, ensuring image plane stability and image clarity across the entire focal length.

[0128] As a possible implementation method, such as Figures 1-6 As shown, the refractive index of the first lens L1 is nd1, and the Abbe number of the first lens L1 is vd1; the refractive index of the seventh lens L7 is nd7, and the Abbe number of the seventh lens L7 is vd7; the refractive index of the ninth lens L9 is nd9, and the Abbe number of the ninth lens L9 is vd9; 1.961≤nd1≤2.060; 25.425≤vd1≤32.312; 1.438≤nd7≤1.498; 81.607≤vd7≤95.099; 2.000≤nd9≤2.012; 25.425≤vd9≤28.892.

[0129] High-refractive-index materials can utilize a gentler curvature at the same optical power, significantly reducing spherical aberration. In this embodiment, the first lens L1 of the focusing lens group G1 uses the aforementioned combination of refractive index and Abbe number, which can effectively control aberration changes during focusing movement. Furthermore, high-refractive-index materials allow for thinner lenses at the same optical power, helping to reduce the weight of the focusing lens group G1 and lower drive power consumption.

[0130] For the zoom lens group G2, after the light passes through the focusing lens group G1, the overall chromatic aberration of the light is still relatively large, even with the correction of the aspherical lens in front. In order to eliminate chromatic aberration, the seventh lens L7 uses a high Abbe number material to further eliminate chromatic aberration after the light passes through the fifth lens L5, suppressing the accumulation of chromatic aberration in the zoom lens group G2, thereby reducing the impact of the zoom lens group G2 on the overall lens chromatic aberration.

[0131] According to the achromatic conditions of cemented doublets, a cemented doublet with a certain optical power can only achieve achromatic effect when two different types of glass are used (the Abbe number of the front lens of the cemented doublet is not equal to the Abbe number of the rear lens). Furthermore, to minimize the difference in optical power between the front and rear lenses of the cemented doublet, the difference in the Abbe numbers of the two types of glass should be as large as possible.

[0132] Therefore, in this embodiment, the sixth lens L6 and the seventh lens L7, as well as the eighth lens L8 and the ninth lens L9, are made of two different types of glass, such as crown glass and flint glass, with the former having a large Abbe number and the latter having a small Abbe number.

[0133] Thus, the seventh lens L7 uses crown glass with a high Abbe number, which creates a large Abbe number difference with the sixth lens L6 (if using a medium-low Abbe number material). This combination can efficiently correct axial chromatic aberration while keeping the overall optical power of the first cemented lens group g1 positive, which is beneficial to the image plane stability during the zoom process.

[0134] The ninth lens L9 uses low Abbe number flint glass, which complements the eighth lens L8 (if using medium to high Abbe number material). This combination can correct magnification chromatic aberration and further balance residual axial chromatic aberration, helping to achieve full-band confocal focusing from 436nm to 870nm.

[0135] As a possible implementation method, such as Figures 1-6 As shown, the refractive index of the twelfth lens L12 is nd12, and the Abbe number of the twelfth lens L12 is vd12; 1.878≤nd12≤2.039; 23.574≤vd12≤28.316.

[0136] In this phase, the lens is already at its end position just before the light reaches the image plane, and the aberration correction effect of the lens at this point directly determines the final image quality. Because aberrations are cumulative during lens transmission, the lens group at the end has the strongest ability to compensate for residual aberrations in the preceding group, and any aberration correction performed at this point will receive the greatest impact weight.

[0137] In this embodiment, the twelfth lens L12 in the fixed lens group G3 is made of a high refractive index, low Abbe number material, which can effectively compensate for the residual aberrations generated by the front lens group (especially the negative optical power focusing lens group G1), making the on-axis and off-axis image quality more balanced. Even when the focusing lens group G1 moves over a wide range, the high refractive index fixed lens group G3 can still maintain a stable image plane position and imaging quality, ensuring image sharpness across the entire focal length, and is also conducive to matching with most 1 / 1.2” chips.

[0138] As a feasible implementation method, the focal length of the zoom lens at the telephoto end is FT, and the focal length of the zoom lens at the wide-angle end is FW; FT / FW=3.2.

[0139] By rationally configuring the optical power distribution and movement trajectory of the focusing lens group G1, the zoom lens group G2, and the fixed lens group G3, the zoom lens in this embodiment possesses an optical zoom capability of no less than 3.2x. It can provide a wide field of view at the wide-angle end and achieve detailed capture of distant targets at the telephoto end, thus adapting to the shooting needs of multiple scenes and distances in security monitoring. This high zoom ratio is achieved while maintaining a large target surface, a large aperture, and a compact size, demonstrating the excellent balance between optical performance and structural compactness in this design.

[0140] 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 twelfth lens L12. 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 lens.

[0141] 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.

[0142] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the zoom lens applicable to the above-described embodiments.

[0143] Example 1

[0144] 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, a zoom lens group G2, and a fixed lens group G3 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, a third lens L3, and a fourth lens L4 arranged sequentially from the object plane to the image plane.

[0146] The zoom lens group G2 includes the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11, arranged sequentially from the object plane to the image plane.

[0147] The fixed lens group G3 includes the twelfth lens L12.

[0148] The aperture stop STO is located in the optical path between the focusing lens group G1 and the zoom lens group G2, and the plane glass CG is located on the image side of the twelfth lens L12.

[0149] 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.

[0150] Table 1 Design values ​​of optical physical parameters for zoom lenses

[0151]

[0152] The surface numbers in Table 1 are assigned according to the surface order of each lens. "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. A positive value means that the surface bends towards the image plane, and a negative value means that the surface bends towards the object plane. "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, which represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current position is air and the refractive index is 1. The material (vd) is the Abbe number, which represents the dispersion characteristics of the material between the current surface and the next surface. A blank space indicates that the current position is air.

[0153] Table 2 shows the zoom interval values ​​for the zoom lens at the wide-angle and telephoto ends in Table 1.

[0154] Table 2 Design values ​​for zoom interval of zoom lenses

[0155]

[0156] In Table 2, the zoom intervals are the different interval values ​​for the zoom lens at the wide-angle end and the telephoto end.

[0157] In this embodiment, the aspherical lens of the zoom lens can satisfy the following formula:

[0158] ;

[0159] in, Along the optical axis, perpendicular to the optical axis at a height of The axial distance from the vertex of the surface at the location of the surface; Indicates the curvature at the vertex of an aspherical surface; , , , and These are the higher-order aspheric coefficients corresponding to the fourth, sixth, eighth, tenth, and twelfth orders of aspheric surfaces. These can be combined to form higher-order terms for the corresponding aspherical surfaces.

[0160] For example, Table 3 details the aspherical coefficients of each lens in this embodiment one by way of a feasible implementation.

[0161] Table 3 Design values ​​of aspherical coefficients for various lenses in zoom lenses

[0162]

[0163] The zoom lens in this embodiment can achieve the following technical specifications:

[0164] Table 4 Technical Specifications of Zoom Lenses

[0165]

[0166] Figure 7 The curve shows the modulation transfer function (MTF) of the zoom lens provided in Embodiment 1 of this invention at infinity object distance in the visible light band at the wide-angle end. This curve reflects the imaging performance of the lens when shooting at a long distance. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value across the entire field of view (1 field of view) is greater than 0.4, indicating that the zoom lens has good resolution and imaging quality at the wide-angle end, meeting the requirements of 4K cameras.

[0167] Figure 8The curve shows the modulation transfer function (MTF) of the zoom lens provided in Embodiment 1 of this invention at a wide-angle end of 1.5 meters in the visible light band. This curve reflects the imaging performance of the lens during close-up shooting. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, measured in lines pairs per millimeter (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with a dominant wavelength set at 546nm. The figure shows that the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 lines pairs / mm, the MTF value within a 0.8 field of view is greater than 0.55, indicating that the zoom lens has good resolution and imaging quality at the wide-angle end, meeting the requirements of 4K cameras.

[0168] Figure 9 This figure shows the defocus modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 1 of the present invention at an infinity object distance in the near-infrared band at the wide-angle end. The curve is simulated for a spatial frequency of 120 line pairs / mm (cycles / mm). The vertical axis represents the MTF value (dimensionless), and the horizontal axis represents the defocus amount (unit: mm). The near-infrared band used in the simulation ranges from 830nm to 870nm, with a dominant wavelength of 850nm. As can be seen from the figure, the defocus amount at this frequency is controlled within a reasonable range at different fields of view. Specifically, at the 0 field of view (optical axis) position, the defocus amount is less than 0.005mm, and the MTF is greater than 0.2 on all other field-of-view axes. This indicates that the zoom lens has good resolution and image quality at the wide-angle end, meeting the requirements of 4K cameras.

[0169] Figure 10 The curve shows the modulation transfer function (MTF) of the zoom lens provided in Embodiment 1 of this invention at infinity object distance in the visible light band. This curve reflects the imaging performance of the lens when shooting at long distances. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value across the entire field of view (1 field of view) is greater than 0.45, indicating that the zoom lens has good resolution and imaging quality at the telephoto end, meeting the requirements of 4K cameras.

[0170] Figure 11This figure shows the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 1 of the present invention at a telephoto distance of 3 meters in the visible light band. This curve reflects the imaging performance of the lens when shooting at close range at the telephoto end. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value within a 0.8 field of view is greater than 0.55, indicating that the zoom lens has good resolution and imaging quality at the telephoto end, meeting the requirements of 4K cameras.

[0171] Figure 12 This figure shows the defocus modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 1 of the present invention at an infinity object distance in the near-infrared band. The curve is simulated for a spatial frequency of 120 line pairs / mm (cycles / mm). The vertical axis represents the MTF value (dimensionless), and the horizontal axis represents the defocus amount (unit: mm). The near-infrared band used in the simulation ranges from 830nm to 870nm, with a dominant wavelength of 850nm. As can be seen from the figure, the defocus amount at this frequency is controlled within a reasonable range under different fields of view. Specifically, at the 0 field of view (optical axis) position, the defocus amount is less than 0.005mm, and the MTF is greater than 0.2 on all other field-of-view axes. This indicates that the zoom lens has good resolution and image quality at the telephoto end, meeting the requirements of 4K cameras.

[0172] Example 2

[0173] 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, a zoom lens group G2, and a fixed lens group G3 arranged sequentially along the optical axis from the object plane to the image plane.

[0174] The focusing lens group G1 includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged sequentially from the object plane to the image plane.

[0175] The zoom lens group G2 includes the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11, arranged sequentially from the object plane to the image plane.

[0176] The fixed lens group G3 includes the twelfth lens L12.

[0177] The aperture stop STO is located in the optical path between the focusing lens group G1 and the zoom lens group G2, and the plane glass CG is located on the image side of the twelfth lens L12.

[0178] 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.

[0179] Table 5 Design values ​​of optical physical parameters for zoom lenses

[0180]

[0181] The surface numbers in Table 5 are assigned according to the surface sequence of each lens. "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. A positive value means that the surface bends towards the image plane, and a negative value means that the surface bends towards the object plane. "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, which represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current position is air and the refractive index is 1. The material (vd) is the Abbe number, which represents the dispersion characteristics of the material between the current surface and the next surface. A blank space indicates that the current position is air.

[0182] Table 6 shows the zoom interval values ​​for the zoom lens at the wide-angle and telephoto ends in Table 5.

[0183] Table 6 Design values ​​for zoom interval of zoom lenses

[0184]

[0185] In Table 6, the zoom intervals are the different interval values ​​for the zoom lens at the wide-angle end and the telephoto end.

[0186] In this embodiment, the aspherical lens of the zoom lens can satisfy the following formula:

[0187] ;

[0188] in, Along the optical axis, perpendicular to the optical axis at a height of The axial distance from the surface at the location to the vertex of that surface; Indicates the curvature at the vertex of an aspherical surface; , , , and These are the higher-order aspheric coefficients corresponding to the fourth, sixth, eighth, tenth, and twelfth orders of aspheric surfaces. These can be combined to form higher-order terms for the corresponding aspherical surfaces.

[0189] For example, Table 7 details the aspherical coefficients of each lens in this second embodiment with a feasible implementation.

[0190] Table 7 Design values ​​of aspherical coefficients for various lenses in zoom lenses

[0191]

[0192] The zoom lens in this second embodiment can achieve the following technical specifications:

[0193] Table 8 Technical Specifications of Zoom Lenses

[0194]

[0195] Figure 13 This is the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 2 of the present invention at infinity object distance in the visible light band at the wide-angle end. This curve reflects the imaging performance of the lens when shooting at a long distance. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranges from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value across the entire field of view (1 field of view) is greater than 0.4, indicating that the zoom lens has good resolution and imaging quality at the wide-angle end, meeting the requirements of 4K cameras.

[0196] Figure 14 This is the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 2 of the present invention at a wide-angle end with an object distance of 1.5 meters in the visible light band. This curve reflects the imaging performance of the lens when shooting at close range. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value within a 0.8 field of view is greater than 0.5, indicating that the zoom lens has good resolution and imaging quality at the wide-angle end, meeting the requirements of 4K cameras.

[0197] Figure 15 This figure shows the defocus modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 2 of the present invention at infinity object distance in the near-infrared band at the wide-angle end. The curve is simulated for a spatial frequency of 120 line pairs / mm (cycles / mm). The vertical axis represents the MTF value (dimensionless), and the horizontal axis represents the defocus amount (unit: mm). The near-infrared band used in the simulation ranges from 830nm to 870nm, with a dominant wavelength of 850nm. As can be seen from the figure, the defocus amount at this frequency is controlled within a reasonable range at different fields of view. Specifically, at the 0 field of view (optical axis) position, the defocus amount is less than 0.005mm, and the MTF is greater than 0.2 on all other field-of-view axes. This indicates that the zoom lens has good resolution and image quality at the wide-angle end, meeting the requirements of 4K cameras.

[0198] Figure 16 This is the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 2 of the present invention at infinity object distance in the visible light band. This curve reflects the imaging performance of the lens during long-distance shooting. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value across the entire field of view (1 field of view) is greater than 0.5, indicating that the zoom lens has good resolution and imaging quality at the telephoto end, meeting the requirements of 4K cameras.

[0199] Figure 17 This is the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 2 of the present invention at a telephoto distance of 3 meters in the visible light band. This curve reflects the imaging performance of the lens when shooting at close range at the telephoto end. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value within a 0.8 field of view is greater than 0.6, indicating that the zoom lens has good resolution and imaging quality at the telephoto end, meeting the requirements of 4K cameras.

[0200] Figure 18This figure shows the defocus modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 2 of the present invention at an infinity object distance in the near-infrared band. The curve is simulated for a spatial frequency of 120 line pairs / mm (cycles / mm). The vertical axis represents the MTF value (dimensionless), and the horizontal axis represents the defocus amount (unit: mm). The near-infrared band used in the simulation ranges from 830nm to 870nm, with a dominant wavelength of 850nm. As can be seen from the figure, the defocus amount at this frequency is controlled within a reasonable range under different fields of view. Specifically, at the 0 field of view (optical axis) position, the defocus amount is less than 0.005mm, and the MTF on all other field-of-view axes is greater than 0.25. This indicates that the zoom lens has good resolution and image quality at the telephoto end, meeting the requirements of 4K cameras.

[0201] Example 3

[0202] 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, a zoom lens group G2, and a fixed lens group G3 arranged sequentially along the optical axis from the object plane to the image plane.

[0203] The focusing lens group G1 includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged sequentially from the object plane to the image plane.

[0204] The zoom lens group G2 includes the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11, arranged sequentially from the object plane to the image plane.

[0205] The fixed lens group G3 includes the twelfth lens L12.

[0206] The aperture stop STO is located in the optical path between the focusing lens group G1 and the zoom lens group G2, and the plane glass CG is located on the image side of the twelfth lens L12.

[0207] 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.

[0208] Table 9 Design values ​​of optical physical parameters for zoom lenses

[0209]

[0210] The surface numbers in Table 9 are assigned according to the surface sequence of each lens. "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. A positive value means that the surface bends towards the image plane, and a negative value means that the surface bends towards the object plane. "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, which represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current position is air and the refractive index is 1. The material (vd) is the Abbe number, which represents the dispersion characteristics of the material between the current surface and the next surface. A blank space indicates that the current position is air.

[0211] Table 10 shows the zoom interval values ​​for the zoom lens at the wide-angle and telephoto ends in Table 9.

[0212] Table 10 Design values ​​for zoom interval of zoom lenses

[0213]

[0214] In Table 10, the zoom intervals are the different interval values ​​of the zoom lens at the wide-angle end and the telephoto end.

[0215] In this embodiment, the aspherical lens of the zoom lens can satisfy the following formula:

[0216] ;

[0217] in, Along the optical axis, perpendicular to the optical axis at a height of The axial distance from the vertex of the surface at the location of the surface; Indicates the curvature at the vertex of an aspherical surface; , , , and These are the higher-order aspheric coefficients corresponding to the fourth, sixth, eighth, tenth, and twelfth orders of aspheric surfaces. These can be combined to form higher-order terms for the corresponding aspherical surfaces.

[0218] For example, Table 11 details the aspherical coefficients of each lens in this embodiment three according to a feasible implementation.

[0219] Table 11 Design values ​​of aspherical coefficients for various lenses in zoom lenses

[0220]

[0221] The zoom lens in this third embodiment can achieve the following technical specifications:

[0222] Table 12 Technical Specifications of Zoom Lenses

[0223]

[0224] Figure 19 This is the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 3 of the present invention at infinity object distance in the visible light band at the wide-angle end. This curve reflects the imaging performance of the lens when shooting at a long distance. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranges from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value across the entire field of view (1 field of view) is greater than 0.5, indicating that the zoom lens has good resolution and imaging quality at the wide-angle end, meeting the requirements of 4K cameras.

[0225] Figure 20 This is the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 3 of the present invention at a wide-angle end of 1.5 meters in the visible light band. This curve reflects the imaging performance of the lens when shooting at close range. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value within a 0.8 field of view is greater than 0.55, indicating that the zoom lens has good resolution and imaging quality at the wide-angle end, meeting the requirements of 4K cameras.

[0226] Figure 21 This figure shows the defocus modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 3 of the present invention at infinity object distance in the near-infrared band at the wide-angle end. The curve is simulated for a spatial frequency of 120 line pairs / mm (cycles / mm). The vertical axis represents the MTF value (dimensionless), and the horizontal axis represents the defocus amount (unit: mm). The near-infrared band used in the simulation ranges from 830nm to 870nm, with a dominant wavelength of 850nm. As can be seen from the figure, the defocus amount at this frequency is controlled within a reasonable range at different fields of view. Specifically, at the 0 field of view (optical axis) position, the defocus amount is less than 0.005mm, and the MTF on all other field-of-view axes is greater than 0.25. This indicates that the zoom lens has good resolution and image quality at the wide-angle end, meeting the requirements of 4K cameras.

[0227] Figure 22 This is the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 3 of the present invention at an infinity object distance in the visible light band. This curve reflects the imaging performance of the lens when shooting at a long distance. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranges from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value across the entire field of view (1 field of view) is greater than 0.4, indicating that the zoom lens has good resolution and imaging quality at the telephoto end, meeting the requirements of 4K cameras.

[0228] Figure 23 This is the modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 3 of the present invention at a telephoto distance of 3 meters in the visible light band. This curve reflects the imaging performance of the lens when shooting at close range at the telephoto end. The vertical axis represents the MTF value (dimensionless); the horizontal axis represents the spatial frequency, with units of line pairs / millimeters (cycles / mm). The visible light band used in the simulation ranged from 436nm to 656nm, with the dominant wavelength set at 546nm. As can be seen from the figure, the MTF values ​​at various frequencies under different fields of view are all controlled within a reasonable range. Specifically, when the spatial frequency reaches 120 line pairs / millimeters, the MTF value within a 0.8 field of view is greater than 0.5, indicating that the zoom lens has good resolution and imaging quality at the telephoto end, meeting the requirements of 4K cameras.

[0229] Figure 24 This figure shows the defocus modulation transfer function (MTF) curve of the zoom lens provided in Embodiment 3 of the present invention at an infinity object distance in the near-infrared band. The curve is simulated for a spatial frequency of 120 line pairs / mm (cycles / mm). The vertical axis represents the MTF value (dimensionless), and the horizontal axis represents the defocus amount (unit: mm). The near-infrared band used in the simulation ranges from 830nm to 870nm, with a dominant wavelength of 850nm. As can be seen from the figure, the defocus amount at this frequency is controlled within a reasonable range at different fields of view. Specifically, at the 0 field of view (optical axis) position, the defocus amount is less than 0.005mm, and the MTF is greater than 0.2 on all other field-of-view axes. This indicates that the zoom lens has good resolution and image quality at the telephoto end, meeting the requirements of 4K cameras.

[0230] It should be noted that, Figures 7-24The black dashed line (Diff. Limit) represents the diffraction limit curve. F1 to F7 are different field-of-view numbers, corresponding to different image heights (from the center to the edge). T and R represent the tangential and radial MTF curves, respectively. RIH (Right Image Height) indicates the image height (unit: mm) corresponding to the field of view. Figures 7-24 As shown, under each field of view (F1 to F7), the MTF curves in both the tangential (T) and radial (R) directions are close to the diffraction limit, indicating that the lens provided by this invention has good aberration control and approaches ideal optical performance. The above results demonstrate that the zoom lens provided by this invention can achieve high-contrast, high-resolution imaging at both the wide-angle and telephoto ends, meeting the requirements of 4K ultra-high-definition cameras for image clarity and detail reproduction, and possesses good practical value and application prospects.

[0231] 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.

[0232] Table 13 Design values ​​of optical physical parameters for zoom lenses

[0233]

[0234] 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, a zoom lens group, and a fixed lens group arranged sequentially along the optical axis from the object plane to the image plane; The fixed lens group is fixedly installed, while the focusing lens group and the zoom lens group are movable along the optical axis. The focusing lens group has negative optical power, the zoom lens group has positive optical power, and the fixed lens group has positive optical power; The zoom lens has 12 lenses with optical power. The focusing lens group includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object plane to the image plane; The zoom lens group includes a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged sequentially from the object plane to the image plane; The fixed lens group includes a twelfth lens; The first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has negative 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, the ninth lens has positive optical power, the tenth lens has negative optical power, and the eleventh lens has negative optical power. The twelfth lens has positive optical power; The focal length of the focusing lens group is F1q, the focal length of the zoom lens group is F2q, the focal length of the fixed lens group is F3q, and the focal length of the zoom lens at the wide-angle end is FW; -2.548≤F1q / FW≤-2.370; 0.985≤F2q / FW≤1.024; 1.365≤F3q / FW≤1.

467.

2. The zoom lens according to claim 1, characterized in that, The sixth lens and the seventh lens together form the first cemented lens group; The eighth lens and the ninth lens together form the second cemented lens group.

3. The zoom lens according to claim 2, characterized in that, The first cemented lens group has positive optical power; The second cemented lens group has positive optical power.

4. The zoom lens according to claim 2, characterized in that, The focal length of the first cemented lens group is F67, the focal length of the second cemented lens group is F89, and the focal length of the zoom lens group is F2q. 1.572≤F67 / F2q≤1.996, 3.660≤F89 / F2q≤5.

201.

5. The zoom lens according to claim 1, characterized in that, The second lens, the fifth lens, the tenth lens, and the eleventh lens are all aspherical lenses; The first lens, the third lens, the fourth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, and the twelfth lens are all spherical lenses.

6. The zoom lens according to claim 1, characterized in that, The zoom lens also includes an aperture stop, which is located in the optical path between the focusing lens group and the zoom lens group.

7. The zoom lens according to claim 1, characterized in that, The object-side surface of the first lens is convex, and the image-side surface of the first lens is concave. The object-side surface of the second lens is convex, and the image-side surface of the second lens is concave. The object-side surface of the third lens is convex, and the image-side surface of the third lens is concave. The object-side surface of the fourth lens is concave, and the image-side surface of the fourth lens is convex. The object-side surface of the fifth lens is convex, and the image-side surface of the fifth lens is convex. The object-side surface of the sixth lens is convex, and the image-side surface of the sixth lens is concave. The object-side surface of the seventh lens is convex, and the image-side surface of the seventh lens is convex. The object-side surface of the eighth lens is concave, and the image-side surface of the eighth lens is also concave. The object-side surface of the ninth lens is convex, and the image-side surface of the ninth lens is convex. The object-side surface of the tenth lens is convex, and the image-side surface of the tenth lens is concave. The object-side surface of the eleventh lens is concave, and the optical axis region of the image-side surface of the eleventh lens is concave. The object-side surface of the twelfth lens is convex, and the image-side surface of the twelfth lens is also convex.

8. The zoom lens according to claim 1, characterized in that, The total length of the zoom lens is TTL, and the maximum movable distance of the zoom lens group is ZOOM; 3.52≤TTL / ZOOM≤3.

78.

9. The zoom lens according to claim 1, characterized in that, The refractive index of the second lens is nd2, and the Abbe number of the second lens is vd2; the refractive index of the fifth lens is nd5, and the Abbe number of the fifth lens is vd5; the refractive index of the tenth lens is nd10, and the Abbe number of the tenth lens is vd10; the refractive index of the eleventh lens is nd11, and the Abbe number of the eleventh lens is vd11; 1.439≤nd2≤1.555; 71.483≤vd2≤94.437; 1.439≤nd5≤1.555; 71.483≤vd5≤94.437; 1.856≤nd10≤1.888; 37.185≤vd10≤40.068; 1.518≤nd11≤1.595; 63.989≤vd11≤70.

274.

10. The zoom lens according to claim 1, characterized in that, The first lens has a refractive index of nd1 and an Abbe number of vd1; the seventh lens has a refractive index of nd7 and an Abbe number of vd7; the ninth lens has a refractive index of nd9 and an Abbe number of vd9; 1.961≤nd1≤2.060; 25.425≤vd1≤32.312; 1.438≤nd7≤1.498; 81.607≤vd7≤95.099; 2.000≤nd9≤2.012; 25.425≤vd9≤28.

892.

11. The zoom lens according to claim 1, characterized in that, The refractive index of the twelfth lens is nd12, and the Abbe number of the twelfth lens is vd12; 1.878≤nd12≤2.039; 23.574≤vd12≤28.316.

Images