A zoom lens

Abstract

The application provides a zoom lens, which comprises, in sequence from an object side to an image side along an optical axis, a focusing lens group with negative optical power, a diaphragm and a zoom lens group with positive optical power; the focusing lens group comprises a first lens with negative optical power, a second lens with negative optical power and a third lens with positive optical power; the zoom lens group comprises a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with negative optical power and an eighth lens with positive optical power; the first lens, the fifth lens and the sixth lens are spherical lenses, and the second lens, the third lens, the fourth lens, the seventh lens and the eighth lens are aspherical lenses. The embodiment of the application provides a zoom lens, which is small in size, large in aperture, high in infrared and low-temperature confocal and capable of cooperating with a 1 / 2.7" chip to realize high image quality.

Description

Technical Field

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

[0002] In the security field, zoom lenses have been widely used due to their advantages such as long shooting distance and wide shooting angle. With the development of technology, cameras are gradually moving towards miniaturization and refinement, which also puts forward more stringent requirements for mainstream zoom lenses.

[0003] Currently, 1 / 2.7″ chips are gradually becoming the mainstream chips on the market and have a wider range of applications, but traditional zoom lenses have defects such as small aperture, non-confocal infrared, and large size. Summary of the Invention

[0004] This invention provides a zoom lens that achieves a small size, large aperture, infrared high and low temperature confocal focusing, and high image quality zoom lens that can be used with a 1 / 2.7″ chip.

[0005] This invention provides a zoom lens, comprising a focusing lens group with negative optical power, an aperture stop, and a zoom lens group with positive optical power, arranged sequentially along the optical axis from the object side to the image side.

[0006] The focusing lens group includes a first lens with negative optical power, a second lens with negative optical power, and a third lens with positive optical power; the zoom lens group includes a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, and an eighth lens with positive optical power.

[0007] The first lens, the fifth lens, and the sixth lens are spherical lenses, while the second lens, the third lens, the fourth lens, the seventh lens, and the eighth lens are aspherical lenses.

[0008] Optionally, the first lens is a convex-concave lens, the second lens is a concave-concave lens, the third lens is a convex-convex lens, the fourth lens is a convex-convex lens, the fifth lens is a concave-concave lens, the sixth lens is a convex-convex lens, the seventh lens is a concave-concave lens, and the eighth lens is a convex-concave lens.

[0009] Optionally, the following conditions must be met:

[0010] -2.170≤F1 / FW≤-1.920, 2.300≤F2 / FW≤2.410;

[0011] Wherein, F1 is the focal length of the focusing lens group, F2 is the focal length of the zoom lens group, and FW is the focal length of the wide-angle end of the zoom lens.

[0012] Optionally, the following conditions must be met:

[0013] 0.15≤S2 / TTL≤0.165, 0.6≤S1 / BFLW≤1.530;

[0014] Wherein, S1 is the distance between the closest and farthest positions of the focusing lens group to the image plane during the movement, S2 is the distance between the closest and farthest positions of the zoom lens group to the image plane during the movement, TTL is the distance between the object-side vertex of the first lens and the image plane at the wide-angle end of the zoom lens, and BFLW is the distance between the image-side vertex of the eighth lens and the image plane at the wide-angle end of the zoom lens.

[0015] Optionally, the fifth lens and the sixth lens are cemented together to form a cemented lens group;

[0016] 8.000≤F56 / F2≤11.000;

[0017] Wherein, F2 is the focal length of the zoom lens group, and F56 is the focal length of the cemented lens group.

[0018] Optionally, the following conditions must be met:

[0019] 12.5≤TTL / EPD≤13.5, 0.18≤L1 / TTL≤0.22

[0020] 1.250≤(R1+R2) / (R1-R2) ≤1.330;

[0021] Wherein, TTL is the distance between the vertex of the object side of the first lens and the image plane at the wide-angle end of the zoom lens, EPD is the entrance pupil diameter of the zoom lens at the wide-angle end, and L1 is the light transmission aperture of the first lens.

[0022] Optionally, the following conditions must be met:

[0023] 0.350≤TTL_S / TTL≤ 0.390; 10.89≤CRAm≤12.92;

[0024] Wherein, TTL_S represents the distance from the vertex of the object side of the first lens to the aperture stop when the zoom lens is at the wide-angle end, TTL is the distance between the vertex of the object side of the first lens and the image plane when the zoom lens is at the wide-angle end, and CRAm represents the maximum angle of the principal rays in the full field of view at the wide-angle end of the zoom lens.

[0025] Optionally, the following conditions must be met:

[0026] |Fw×(Bc-Bg) / Vdmin|≤0.0009;

[0027] Wherein, FW is the focal length at the wide-angle end of the zoom lens, Bc is the axial distance from the focal point of the zoom lens at a wavelength of 656nm to the vertex of the side image of the eighth lens, Bg is the axial distance from the focal point of the zoom lens at a wavelength of 436nm to the vertex of the side image of the eighth lens, and Vdmin is the minimum Abbe number among the first lens to the eighth lens.

[0028] Optionally, the following conditions must be met:

[0029] 1.430≤Nd4≤1.560, 71.600≤Vd4≤94.530;

[0030] Wherein, Nd4 is the refractive index of the fourth lens, and Vd4 is the Abbe number of the fourth lens.

[0031] Optionally, the following conditions must be met:

[0032] FT / FW ≥ 2.3;

[0033] Wherein, FW is the focal length at the wide-angle end of the zoom lens, and FT is the focal length at the telephoto end of the zoom lens.

[0034] The dual-group structure is the simplest architecture for achieving zoom functionality with the fewest lens elements. This means the zoom lens is smaller and can meet the needs of a wider range of applications. Furthermore, with only eight lenses per lens group, material and coating costs can be better controlled, minimizing overall lens cost. It also provides good correction for aberrations, chromatic aberration, and sensitivity. Using this combination of optical power allows for a balance of flexibility across different magnifications, achieving an optimal solution in terms of performance and parameters, meeting a wider range of application requirements while controlling cost. This results in full-band confocal focusing within the 436nm-850nm wavelength range at a 1 / 2.7″ aperture, with a larger aperture and higher image quality, suitable for a wider range of applications. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the zoom lens at the wide-angle end provided in Embodiment 1 of the present invention;

[0036] Figure 2 This is a schematic diagram of the zoom lens at the telephoto end provided in Embodiment 1 of the present invention;

[0037] Figure 3 The lateral chromatic aberration curve of the zoom lens at the wide-angle end provided in Embodiment 1 of the present invention;

[0038] Figures 4-9 This is a ray fan diagram of the zoom lens at the wide-angle end provided in Embodiment 1 of the present invention;

[0039] Figure 10This is an axial aberration curve of the zoom lens at the wide-angle end provided in Embodiment 1 of the present invention;

[0040] Figure 11 This is a chromatic aberration curve of the zoom lens at the telephoto end provided in Embodiment 1 of the present invention.

[0041] Figures 12-17 This is a ray fan diagram of the zoom lens at the telephoto end provided in Embodiment 1 of the present invention;

[0042] Figure 18 This is an axial aberration curve of the zoom lens at the telephoto end provided in Embodiment 1 of the present invention.

[0043] Figure 19 This is a schematic diagram of the zoom lens at the wide-angle end provided in Embodiment 2 of the present invention;

[0044] Figure 20 This is a schematic diagram of the zoom lens at the telephoto end provided in Embodiment 2 of the present invention;

[0045] Figure 21 This is a chromatic aberration curve of the zoom lens at the wide-angle end provided in Embodiment 2 of the present invention;

[0046] Figures 22-27 This is a ray fan diagram of the zoom lens at the wide-angle end provided in Embodiment 2 of the present invention;

[0047] Figure 28 This is an axial aberration curve of the zoom lens at the wide-angle end provided in Embodiment 2 of the present invention;

[0048] Figure 29 This is a chromatic aberration curve of the zoom lens at the telephoto end provided in Embodiment 2 of the present invention;

[0049] Figures 30-35 This is a ray fan pattern of the zoom lens at the telephoto end provided in Embodiment 2 of the present invention;

[0050] Figure 36 This is an axial aberration curve of the zoom lens at the telephoto end provided in Embodiment 2 of the present invention;

[0051] Figure 37 This is a schematic diagram of the zoom lens at the wide-angle end provided in Embodiment 3 of the present invention;

[0052] Figure 38 This is a schematic diagram of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention;

[0053] Figure 39 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.

[0054] Figures 40-45This is a ray fan diagram of the zoom lens at the wide-angle end provided in Embodiment 3 of the present invention;

[0055] Figure 46 This is an axial aberration curve of the zoom lens at the wide-angle end provided in Embodiment 3 of the present invention;

[0056] Figure 47 This is a chromatic aberration curve of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention;

[0057] Figures 48-53 This is the ray fan pattern of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention;

[0058] Figure 54 This is the axial aberration curve of the zoom lens at the telephoto end provided in Embodiment 3 of the present invention. Detailed Implementation

[0059] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0060] Example 1

[0061] Figure 1 This is a schematic diagram of the zoom lens at the wide-angle end provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the zoom lens at the telephoto end according to Embodiment 1 of the present invention; see reference. Figure 1 and Figure 2 The zoom lens includes a focusing lens group G1 with negative optical power, an aperture stop STO, and a zoom lens group G2 with positive optical power, arranged sequentially from the object side to the image side along the optical axis. The focusing lens group G1 includes a first lens L1 with negative optical power, a second lens L2 with negative optical power, and a third lens L3 with positive optical power. The zoom lens group G2 includes a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, a sixth lens L6 with positive optical power, a seventh lens L7 with negative optical power, and an eighth lens L8 with positive optical power. The first lens L1, the fifth lens L5, and the sixth lens L6 are spherical lenses, while the second lens L2, the third lens L3, the fourth lens L4, the seventh lens L7, and the eighth lens L8 are aspherical lenses.

[0062] The aperture stop STO is fixedly placed within the entire zoom lens. By changing the positions of the focusing lens group G1 and the zoom lens group G2 on the optical axis, the zoom lens can switch between the wide-angle and telephoto ends.

[0063] The dual-group structure is the simplest architecture for achieving zoom functionality with the fewest lens elements. This means the zoom lens is smaller and can meet the needs of a wider range of applications. Furthermore, with only eight lenses per lens group, material and coating costs can be better controlled, minimizing overall lens cost. It also provides good correction for aberrations, chromatic aberration, and sensitivity. Using this combination of optical power allows for a balance of flexibility across different magnifications, achieving an optimal solution in terms of performance and parameters, meeting a wider range of application requirements while controlling cost. This results in full-band confocal focusing within the 436nm-850nm wavelength range at a 1 / 2.7″ aperture, with a larger aperture and higher image quality, suitable for a wider range of applications.

[0064] For example, the eighth lens L8 exhibits inversion. During zooming, the movement trajectory of the eighth lens L8 is not monotonically forward or backward, but rather it first moves in one direction and then "reverses" a portion of its path, ultimately forming a non-linear motion curve with an inflection point. This is used for non-linear compensation of optical aberrations in zoom lenses.

[0065] Optionally, the first lens L1 is a convex-concave lens, the second lens L2 is a concave-concave lens, the third lens L3 is a convex-convex lens, the fourth lens L4 is a convex-convex lens, the fifth lens L5 is a concave-concave lens, the sixth lens L6 is a convex-convex lens, the seventh lens L7 is a concave-concave lens, and the eighth lens L8 is a convex-concave lens. In a convex-concave lens, the object-side face is convex towards the object, and the image-side face is concave towards the image. A concave-concave lens is also called a biconcave lens, where both the object-side and image-side face are concave towards the image. A convex-convex lens is also called a biconvex lens, where both the object-side and image-side face are convex towards the image.

[0066] Optionally, the zoom lens satisfies the following parameters: -2.170≤F1 / FW≤-1.920, 2.300≤F2 / FW≤2.410; where F1 is the focal length of the focusing lens group G1, F2 is the focal length of the zoom lens group G2, and FW is the focal length at the wide-angle end of the zoom lens. Using this lens configuration achieves a reasonable balance of optical power, allowing light to pass through the zoom lens more smoothly and significantly correcting the impact of advanced aberrations of the zoom lens on image quality.

[0067] Optionally, the zoom lens satisfies: 0.15 ≤ S2 / TTL ≤ 0.165, 0.6 ≤ S1 / BFLW ≤ 1.530; where S1 is the distance between the closest and farthest positions of the focusing lens group G1 and the image plane during movement, S2 is the distance between the closest and farthest positions of the zoom lens group G2 and the image plane during movement, TTL is the distance between the vertex of the object side of the first lens L1 and the image plane at the wide-angle end of the zoom lens, and BFLW is the distance between the vertex of the image side of the eighth lens L8 and the image plane at the wide-angle end of the zoom lens. By controlling the position of the zoom lens group G2, the reciprocating motion of the focusing lens group G1 can be indirectly controlled, greatly reducing the size of the zoom lens and achieving a larger magnification, thus expanding the application scenarios of the zoom lens.

[0068] Optionally, both the focusing lens group G1 and the zoom lens group G2 contain at least two plastic aspherical lenses; and the zoom lens group G2 contains a cemented lens group consisting of at least two glass spherical lenses. For example, the fifth lens L5 and the sixth lens L6 are cemented together to form a cemented lens group; 8.000≤F56 / F2≤11.000; where F2 is the focal length of the zoom lens group G2 and F56 is the focal length of the cemented lens group. One of the main factors affecting the image quality of a zoom lens is the aberration of the zoom lens itself. In a zoom lens, because the lens groups need to move relative to each other, controlling the aberration of only one state is insufficient. Adding aspherical lenses to each lens group can make the aberration of each configuration of the zoom lens more balanced, and overall correction of the zoom lens can achieve clear imaging across the entire wavelength range.

[0069] Furthermore, glass and plastic can compensate for each other's weaknesses. Using a combination of glass and plastic lenses in zoom lenses can effectively balance the lens's resolution under high and low temperatures, ensuring good resolution within the range of -40 to 80°C. At the same time, using a suitable combination of glass lenses also has a good corrective effect on aberrations in zoom lenses. In addition, when light passes through the STO (Side Stop) aperture, certain higher aberrations will occur. Cemented lens groups also have a certain suppressive effect on higher aberrations, especially chromatic aberration. Using cemented lens groups after the STO aperture can prevent excessive aberrations that cannot be corrected when light propagates to the rear of the zoom lens, thus ensuring the relative illumination and image quality of the zoom lens.

[0070] Optionally, the zoom lens satisfies the following: 12.5≤TTL / EPD≤13.5, 0.18≤L1 / TTL≤0.22, 1.250≤(R1+R2) / (R1-R2) ≤1.330; where TTL is the distance between the vertex of the object side of the first lens L1 and the image plane at the wide-angle end of the zoom lens, EPD is the entrance pupil diameter of the zoom lens at the wide-angle end, and L1 is the light-transmitting aperture of the first lens L1. By controlling the relationship between the total length of the lens (i.e., TTL) and the entrance pupil diameter, the zoom lens can be guaranteed to have the largest possible aperture, meeting the needs of use in dark conditions; in addition, controlling the relationship between the position of the incident light rays at the edge of the first lens L1 and the total length of the lens, as well as the radius of curvature of the first lens L1, also ensures the maximum aperture that can be passed through in the structure, improving the light incident range of the zoom lens and enhancing the image quality of the zoom lens.

[0071] Optionally, the zoom lens satisfies: 0.350≤TTL_S / TTL≤ 0.390; 10.89≤CRAm≤12.92; where TTL_S represents the distance from the vertex of the object side of the first lens L1 to the aperture stop STO at the wide-angle end of the zoom lens, TTL is the distance between the vertex of the object side of the first lens L1 and the image plane at the wide-angle end of the zoom lens, and CRAm represents the maximum principal ray angle of the zoom lens in the full field of view at the wide-angle end. By controlling the ratio of the distance from the vertex of the first lens L1 to the aperture stop STO at the wide-angle end of the zoom lens to the axial distance from the vertex of the first lens L1 to the center of the image plane at the wide-angle end of the zoom lens, the overall aperture can be compressed and the optical power of the front and rear lens groups can be balanced to achieve the purpose of aberration correction; at the same time, controlling the maximum principal ray angle of the zoom lens can ensure the matching between the zoom lens and the chip, prevent other imaging problems such as vignetting, and improve the imaging quality of the zoom lens while meeting the requirements of a compact structure.

[0072] Optionally, the zoom lens satisfies: |Fw×(Bc-Bg) / Vdmin|≤0.0009; where Fw is the focal length at the wide-angle end of the zoom lens, Bc is the axial distance from the focal point of the zoom lens at a wavelength of 656nm to the vertex of the image side of the eighth lens L8, Bg is the axial distance from the focal point of the zoom lens at a wavelength of 436nm to the vertex of the image side of the eighth lens L8, and Vdmin is the minimum Abbe number among the first lens L1 to the eighth lens L8. When the zoom lens meets the above condition, it can ensure that the zoom lens can produce clear images across the entire focal length range, minimize chromatic aberration, and further improve the image quality of the zoom lens.

[0073] Optionally, at least one glass aspherical lens is included in the zoom lens group G2. For example, the fourth lens L4 is a glass aspherical lens. The second lens L2, third lens L3, seventh lens L7, and eighth lens L8 are plastic aspherical lenses. The zoom lens satisfies: 1.430≤Nd4≤1.560, 71.600≤Vd4≤94.530; where Nd4 is the refractive index of the fourth lens L4, and Vd4 is the Abbe number of the fourth lens L4. The glass aspherical lens combines the high and low temperature stability of glass lenses with the aberration correction capability of plastic lenses. After light passes through the aperture stop STO, it first passes through the glass aspherical lens, which can prevent excessive and difficult-to-eliminate high-order aberrations and chromatic aberrations from appearing at the rear of the zoom lens; it improves the image quality of the zoom lens while ensuring its high and low temperature performance, meeting the needs of use in complex environments.

[0074] Optionally, the zoom lens satisfies: FT / FW ≥ 2.3; where FW is the focal length at the wide-angle end of the zoom lens, and FT is the focal length at the telephoto end. By controlling the focal length ratio at the wide-angle and telephoto ends of the lens, the zoom range and focal length range of the lens can be controlled to meet the usage needs under more conditions.

[0075] For example, the zoom lens may further include a flat glass CG, which is located on the side of the eighth lens L8 away from the first lens L1 and on the side of the eighth lens L8 near the image plane, to protect the photosensitive chip in the imaging sensor. The photosensitive chip is used to convert the light signals collected by the zoom lens into electrical signals, thereby ensuring the imaging effect of the zoom lens.

[0076] In a zoom lens, the focusing lens group G1 and the zoom lens group G2 can be housed in a single lens barrel. Figure 1 , Figure 2 (Not shown in the image). The focusing lens group G1 and the zoom lens group G2 can reciprocate along the optical axis within the lens barrel. Through the combined movement of the focusing lens group G1 and the zoom lens group G2, the focal length of the zoom lens can be continuously changed from short focal length to long focal length, ensuring high image quality at all focal points.

[0077] Understandably, during the zoom process achieved by moving the focusing lens group G1 and the zoom lens group G2, the zoom lens is at its shortest focal length, i.e., at the wide-angle end, and at its longest focal length, i.e., at the telephoto end. At the wide-angle end and the telephoto end, the zoom lens has different focal lengths and optical powers, and also different shapes.

[0078] Table 1. Design values ​​for a zoom lens in Example 1.

[0079]

[0080] Table 1 shows one design value for the zoom lens in Embodiment 1. The specific values ​​can be adjusted according to product requirements and are not intended to limit the embodiments of the present invention. The zoom lens shown in Table 1 can be... Figure 1 and Figure 2 As shown in Table 1, a lens typically consists of two surfaces, each serving as a refractive surface. The surface numbers in Table 1 are assigned based on the surfaces of each lens. Surface number 1 represents the front surface (object side) of the first lens L1, surface number 2 represents the rear surface (image side) of the first lens L1, and so on. The radius of curvature represents the degree of curvature of the lens surface. A positive radius of curvature value indicates that the center of curvature is on the side of the surface closer to the image plane IMA; a negative radius of curvature value indicates that the center of curvature is on the side of the surface farther from the image plane IMA. "Inf" in the radius of curvature column indicates that the surface is planar with an infinite radius of curvature, expressed in mm. The value in the thickness column represents the axial distance between the centers of the current surface and the next surface, expressed in mm. The refractive index column represents the refractive index of the medium between the current and next surfaces, representing the material's ability to deflect light between them. The blank space in the refractive index column represents the refractive index of air, which is 1. The Abbe number represents the dispersion characteristics of light by the material between the current surface and the next surface; a blank space indicates that the current location is air.

[0081] Table 2. Zoom interval design values ​​for the zoom lens in Example 1

[0082] Wide-angle end telephoto end Zoom interval 1 4.825 1.749 Zoom interval 2 4.218 -0.860 Zoom interval 3 4.000 9.082

[0083] In Table 2, the zoom interval is the value between the wide-angle and telephoto ends of the zoom lens. In Table 1, zoom interval 1 is 4.825mm at the wide-angle end and 1.749mm at the telephoto end. Similarly, zoom intervals 2 and 3 will not be described further.

[0084] For example, an aspherical lens (including a glass aspherical lens) satisfies the following formula:

[0085] in, Along the optical axis, perpendicular to the optical axis at a height of The axial distance from the surface at the location of the point to the vertex of the surface is the axial sagitta in the Z direction of the aspherical surface. The height of the aspherical surface; It represents the curvature at the vertex of an aspherical surface, and is numerically the reciprocal of the radius of curvature; To fit the conic coefficients; These are the higher-order aspheric coefficients corresponding to the second, fourth, sixth, eighth, tenth, twelfth, and fourteenth orders of aspheric surfaces.

[0086] Table 3. Design values ​​of aspherical coefficient for zoom lenses in Example 1.

[0087]

[0088] The meaning of "Face Number" in Table 3 is consistent with that in Table 1. In the embodiments of this invention, "E" represents a base-10 exponent.

[0089] For example, in Embodiment 1, the maximum achievable image diameter of the zoom lens at both the wide-angle and telephoto ends is 6.609 mm. The focal length of the zoom lens at the wide-angle end is 3.170 mm, and the focal length at the telephoto end is 7.430 mm. The zoom lens is suitable for wavelengths from 436 nm to 850 nm at both the wide-angle and telephoto ends. The total optical length of the zoom lens at both the wide-angle and telephoto ends is 31.65 mm.

[0090] Figure 3 This diagram illustrates the transverse chromatic aberration curve at infinity object distance at the wide-angle end of a zoom lens; the vertical axis represents the field of view, 0 indicates being on the optical axis, and the vertex of the vertical axis represents the maximum image height; the dominant wavelength is 546 nm, and the horizontal axis represents the offset relative to the dominant wavelength, in micrometers (μm). Figure 3 It can be seen that the transverse chromatic aberration of different wavelengths is controlled within a small range, indicating that the transverse chromatic aberration of the zoom lens is well controlled at the wide-angle end, which can meet the application requirements under normal conditions.

[0091] Ray fan diagrams are one of the commonly used evaluation methods by optical designers. Figures 4-9 This is a fan plot of light rays at infinity at the wide-angle end of the zoom lens, under different fields of view. In a single plot, the horizontal axis represents the normalized beam aperture in the x and y directions, and the vertical axis represents the transverse aberration. Ideally, each curve should completely coincide with the horizontal axis, at which point all rays in that field of view focus 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 fan plot not only reflects monochromatic aberrations at different wavelengths but also indicates the magnitude of transverse chromatic aberration. Figures 4-9 It can be seen that this zoom lens does not have obvious abrupt changes in visible light and infrared wavelengths at the wide-angle end, and the curves of each color do not have obvious dispersion. This indicates that this zoom lens also has good correction for chromatic aberration and transverse aberration at the wide-angle end, which meets the usage requirements of this zoom lens.

[0092] Lens axial aberration curves can effectively represent the spherical aberration and other parameters of zoom lenses under different wavelength conditions, such as... Figure 10As shown; the vertical direction in the figure represents the normalized aperture, 0 indicates on the optical axis, and the vertex represents the maximum pupil radius; the dominant wavelength is 546nm, and the horizontal direction represents the offset relative to the imaging plane, in millimeters (mm). Figure 10 It can be seen that the axial aberrations of different wavelengths are all within a reasonable range across the entire normalized aperture, and there is no obvious color difference between visible light and infrared light, achieving the effect of forming a clear image across the entire wavelength range.

[0093] Figure 11 This is a graph showing the transverse chromatic aberration at infinity at the telephoto end of a zoom lens; from Figure 11 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 good control over the chromatic aberration along the vertical axis at the telephoto end, which can meet the application requirements under normal conditions.

[0094] Figures 12-17 This is a fan-shaped diagram of the light rays at infinity at the telephoto end of a zoom lens, under different fields of view. Figures 12-17 It can be seen that at the telephoto end, there are no obvious abrupt changes in the visible light and infrared wavelengths of this zoom lens; the curves of each color are also not obviously dispersed, indicating that this zoom lens also has good correction for chromatic aberration and transverse aberration at the telephoto end, which meets the usage requirements of this zoom lens.

[0095] Figure 18 This is a graph showing the axial aberration of a zoom lens at the telephoto end; from Figure 18 It can be seen that under full pupil, there is no obvious aberration between visible light and infrared light, which meets the basic requirement of clear imaging at night and achieves the effect of clear imaging across the entire spectrum.

[0096] Example 2

[0097] Similarities to the above embodiments will not be repeated here.

[0098] Table 4. Design values ​​for the zoom lens in Example 2.

[0099]

[0100] Table 4 shows one design value for the zoom lens in Embodiment 2. The specific values ​​can be adjusted according to product requirements and are not intended to limit the embodiments of the present invention. The zoom lens shown in Table 4 can be... Figure 19 and Figure 20 As shown in the image.

[0101] Table 5. Zoom interval design values ​​for the zoom lens in Example 2.

[0102] Wide-angle end telephoto end Zoom interval 1 5.378 0.972 Zoom interval 2 4.371 -0.600 Zoom interval 3 1.909 6.880

[0103] Table 6. Design values ​​of aspherical coefficient for zoom lenses in Example 2.

[0104]

[0105] For example, in Embodiment 2, the maximum achievable diameter of the image plane at both the wide-angle and telephoto ends of the zoom lens is 6.609 mm. The focal length of the zoom lens at the wide-angle end is 3.004 mm, and the focal length at the telephoto end is 7.510 mm. The zoom lens is suitable for wavelengths from 436 nm to 850 nm at both the wide-angle and telephoto ends. The total optical length of the zoom lens at both the wide-angle and telephoto ends is 31.65 mm.

[0106] Figures 21-36 The descriptions of transverse chromatic aberration, ray fan, and axial aberration are related to... Figures 3-18 Similarly, I will not elaborate further here.

[0107] Example 3

[0108] Similarities to the above embodiments will not be repeated here.

[0109] Table 7. One design value for the zoom lens in Example 3.

[0110]

[0111] Table 7 shows one design value for the zoom lens in Embodiment 3. The specific values ​​can be adjusted according to product requirements and are not intended to limit the embodiments of the present invention. The zoom lens shown in Table 7 can be... Figure 37 and Figure 38 As shown in the image.

[0112] Table 8. Zoom interval design values ​​for the zoom lens in Example 3.

[0113] Wide-angle end telephoto end Zoom interval 1 4.791 0.891 Zoom interval 2 4.096 -0.791 Zoom interval 3 2.204 7.091

[0114] Table 9. Design values ​​of aspherical coefficient for zoom lenses in Example 3.

[0115]

[0116] For example, in Embodiment 3, the maximum achievable diameter of the image plane at both the wide-angle and telephoto ends of the zoom lens is 6.609 mm. The focal length at the wide-angle end is 3.058 mm, and the focal length at the telephoto end is 7.400 mm. The zoom lens is suitable for wavelengths from 436 nm to 850 nm at both the wide-angle and telephoto ends. The total optical length of the zoom lens at both the wide-angle and telephoto ends is 31.65 mm.

[0117] Figures 39-54 The descriptions of transverse chromatic aberration, ray fan, and axial aberration are related to... Figures 3-18Similarly, I will not elaborate further here.

[0118] Table 10 Parameter design values ​​for each embodiment

[0119]

[0120] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A zoom lens, characterized in that, It consists of a focusing lens group with negative optical power, an aperture, and a zoom lens group with positive optical power, arranged sequentially from the object side to the image side along the optical axis. The focusing lens group includes three lenses: a first lens with negative optical power, a second lens with negative optical power, and a third lens with positive optical power. The zoom lens group includes five lenses: a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, and an eighth lens with positive optical power. The first lens, the fifth lens, and the sixth lens are spherical lenses, while the second lens, the third lens, the fourth lens, the seventh lens, and the eighth lens are aspherical lenses. ， ； Wherein, F1 is the focal length of the focusing lens group, F2 is the focal length of the zoom lens group, and FW is the focal length of the wide-angle end of the zoom lens.

2. The zoom lens according to claim 1, characterized in that, The first lens is a convex-concave lens, the second lens is a concave-concave lens, the third lens is a convex-convex lens, the fourth lens is a convex-convex lens, the fifth lens is a concave-concave lens, the sixth lens is a convex-convex lens, the seventh lens is a concave-concave lens, and the eighth lens is a convex-concave lens.

3. The zoom lens according to claim 1, characterized in that, satisfy: ， ； Wherein, S1 is the distance between the closest and farthest positions of the focusing lens group to the image plane during the movement, S2 is the distance between the closest and farthest positions of the zoom lens group to the image plane during the movement, TTL is the distance between the object-side vertex of the first lens and the image plane at the wide-angle end of the zoom lens, and BFLW is the distance between the image-side vertex of the eighth lens and the image plane at the wide-angle end of the zoom lens.

4. The zoom lens according to claim 1, characterized in that, The fifth lens and the sixth lens are cemented together to form a cemented lens group; ； Wherein, F56 is the focal length of the cemented lens group.

5. The zoom lens according to claim 1, characterized in that, satisfy: ， ， ； Wherein, TTL is the distance between the vertex of the object side of the first lens and the image plane at the wide-angle end of the zoom lens, EPD is the entrance pupil diameter of the zoom lens at the wide-angle end, L1 is the light-transmitting aperture of the first lens, R1 is the radius of curvature of the object side of the first lens, and R2 is the radius of curvature of the image side of the first lens.

6. The zoom lens according to claim 1, characterized in that, satisfy: ； ； Wherein, TTL_S represents the distance from the vertex of the object side of the first lens to the aperture stop when the zoom lens is at the wide-angle end, TTL is the distance between the vertex of the object side of the first lens and the image plane when the zoom lens is at the wide-angle end, and CRAm represents the maximum angle of the principal rays in the full field of view at the wide-angle end of the zoom lens.

7. The zoom lens according to claim 1, characterized in that, satisfy: ； Wherein, Bc is the axial distance from the focal point of the zoom lens at a wavelength of 656nm to the vertex of the side image of the eighth lens, Bg is the axial distance from the focal point of the zoom lens at a wavelength of 436nm to the vertex of the side image of the eighth lens, and Vdmin is the minimum Abbe number among the first lens to the eighth lens.

8. The zoom lens according to claim 1, characterized in that, satisfy: ， ； Wherein, Nd4 is the refractive index of the fourth lens, and Vd4 is the Abbe number of the fourth lens.

9. The zoom lens according to claim 1, characterized in that, satisfy: ； Wherein, FT is the focal length at the telephoto end of the zoom lens.

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