Low-distortion large-target-surface lens

Abstract

The utility model discloses a low-distortion large-target-surface lens, which sequentially comprises a first lens group, a diaphragm and a second lens group from an object side to an image side, and the first lens group sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens from the object side to the image side; the second lens group sequentially comprises a seventh lens, an eighth lens and a ninth lens from the object side to the image side; the first lens has positive focal power, the second lens has negative focal power, the third lens has negative focal power, the fourth lens has positive focal power, the fifth lens has positive focal power, the sixth lens has positive focal power, the seventh lens has positive focal power, the eighth lens has negative focal power, and the fifth lens has positive focal power. And the ninth lens has positive focal power. According to the utility model, the whole lens system can achieve the effect of low distortion, so that the lens can better gather light rays and project the light rays to a larger imaging side.

Description

Technical Field

[0001] The utility model relates to the technical field of lenses, in particular to a low-distortion large-image-plane lens. Background Art

[0002] However, the existing drone lenses on the market often fail to meet the requirements of 4K ultra-high-definition picture quality, a large imaging image plane, and low distortion at the same time. For example, the patent document (CN114994879A) proposes a drone lens. By optimizing the lens combination and focal length configuration, various aberrations of the optical lens can be fully corrected, which can improve the resolution of lens imaging, optimize distortion, and optimize optical performances such as the chief ray angle (CRA). However, it is difficult to adapt to ultra-high-definition picture quality. If the image field is enlarged, high-order aberrations are likely to be introduced. Due to its insufficient correction ability, the edge picture quality is likely to decline, resulting in low imaging quality. Summary of the Utility Model

[0003] The technical problem to be solved by the utility model is that the existing drone lenses often fail to meet the requirements of 4K ultra-high-definition picture quality, a large imaging image plane, and low distortion at the same time.

[0004] To solve the above technical problem, the utility model provides a low-distortion large-image-plane lens, which sequentially includes a first lens group, a diaphragm, and a second lens group from the object side to the image side. The first lens group sequentially includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens from the object side to the image side; the second lens group sequentially includes a seventh lens, an eighth lens, and a ninth lens from the object side to the image side; the first lens has a positive optical power, the second lens has a negative optical power, the third lens has a negative optical power, the fourth lens has a positive optical power, the fifth lens has a positive optical power, the sixth lens has a positive optical power, the seventh lens has a positive optical power, the eighth lens has a negative optical power, and the ninth lens has a positive optical power.

[0005] Further, the object side surface of the first lens is convex in the paraxial region, and its image side surface is concave in the paraxial region. The focal length of the first lens group is FL, the focal length of the first lens is F1, the refractive index of the first lens is N1, the Abbe number of the first lens is V1, and the thickness of the first lens is T1, and the following relational expressions are satisfied:

[0006] 2.8 < F1 / FL < 3.2;

[0007] 1.65 < N1 < 1.80;

[0008] 50 < V1 < 75;

[0009] 0.25 < T1 / FL < 0.3.

[0010] Further, the object side surface of the second lens is convex near the axis, and its image side surface is concave near the axis. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the second lens is F2, the refractive index of the second lens is N2, the Abbe number of the second lens is V2, the thickness of the second lens is T2, the distance between the first lens and the second lens is d1, and the following relational expressions are satisfied:

[0011] -1.3 < F2 / FL < -0.9;

[0012] 1.70 < N2 < 1.80;

[0013] 45 < V2 < 60;

[0014] 0.04 < T2 / FL < 0.075;

[0015] 0.02 < d1 / F < 0.05.

[0016] Further, the image side surface of the third lens is concave near the axis. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the third lens is F3, the refractive index of the third lens is N3, the thickness of the third lens is T3, the Abbe number of the third lens is V3, the distance between the second lens and the third lens is d2, and the following relational expressions are satisfied:

[0017] -1 < F3 / FL < -0.25;

[0018] 1.75 < N3 < 1.90;

[0019] 17 < V3 < 35;

[0020] 0.04 < T3 / FL < 0.075;

[0021] 0.32 < d2 / F < 0.55.

[0022] Further, the fourth lens and the fifth lens are cemented together to form a doublet lens. The object side surface of the fourth lens is convex near the axis. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the fourth lens is F4, the refractive index of the fourth lens is N4, the Abbe number of the fourth lens is V4, the thickness of the fourth lens is T4, the distance between the third lens and the fourth lens is d3, and the following relational expressions are satisfied:

[0023] 0.8 < F4 / FL < 1.2;

[0024] 1.85 < N4 < 2.00;

[0025] 17 < V4 < 25;

[0026] 0.2 < T4 / FL < 0.3;

[0027] 0.14 < d3 / F < 0.21.

[0028] Further, the image side surface of the fifth lens is convex in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the fifth lens is F5, the refractive index of the fifth lens is N5, the Abbe number of the fifth lens is V5, the thickness of the fifth lens is T5, the distance between the fifth lens and the sixth lens is d4, and the following relational expressions are satisfied:

[0029] 0.6 < F5 / FL < 1.1;

[0030] 1.45 < N5 < 1.60;

[0031] 45 < V5 < 60;

[0032] 0.4 < T5 / FL < 0.5;

[0033] 0.015 < d4 / F < 0.025.

[0034] Further, the object side surface of the sixth lens is convex in the paraxial region, and its image side surface is concave in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the sixth lens is F6, the refractive index of the sixth lens is N6, the Abbe number of the sixth lens is V6, the thickness of the sixth lens is T6, the distance between the sixth lens and the diaphragm is d5, and the following relational expressions are satisfied:

[0035] 7.5 < F6 / FL < 10;

[0036] 1.45 < N6 < 1.65;

[0037] 60 < V6 < 80;

[0038] 0.2 < T6 / FL < 0.3;

[0039] 0.065 < d5 / F < 0.085.

[0040] Further, the seventh lens and the eighth lens are cemented together to form a doublet lens. The image side of the seventh lens is convex in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the second lens group is FB, the focal length of the seventh lens is F7, the refractive index of the seventh lens is N7, the Abbe number of the seventh lens is V7, the thickness of the seventh lens is T7, and the distance between the aperture stop and the seventh lens is d6, and the following relational expressions are satisfied:

[0041] 0.25 < F7 / FB < 0.5;

[0042] 1.5 < N7 < 1.65;

[0043] 65 < V7 < 70;

[0044] 0.15 < T7 / FB < 0.25;

[0045] 0.035 < d6 / F < 0.055.

[0046] Further, the object side of the eighth lens is concave in the paraxial region, and its image side is convex in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the second lens group is FB, the focal length of the eighth lens is F8, the refractive index of the eighth lens is N8, the Abbe number of the eighth lens is V8, the thickness of the eighth lens is T8, and the distance between the eighth lens and the ninth lens is d8, and the following relational expressions are satisfied:

[0047] -0.65 < F8 / FB < 0.43;

[0048] 1.70 < N8 < 1.85;

[0049] 17 < V8 < 35;

[0050] 0.03 < T8 / FB < 0.065;

[0051] 0.31 < d8 / F < 0.36.

[0052] Further, the object side of the ninth lens is convex in the paraxial region, and its image side is convex in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the second lens group is FB, the focal length of the ninth lens is F9, the refractive index of the ninth lens is N9, the Abbe number of the ninth lens is V9, the thickness of the ninth lens is T9, and the distance between the ninth lens and the imaging surface is d8, and the following relational expressions are satisfied:

[0053] 1.55 < F9 / FB < 2.10;

[0054] 1.65 < N9 < 1.80;

[0055] 45 < V9 < 65;

[0056] 0.15 < T9 / FB < 0.25;

[0057] 0.63 < d9 / F < 0.75.

[0058] Compared with the prior art, the beneficial effects of the low-distortion large target surface lens according to the embodiment of the present invention are as follows:

[0059] From the object side to the image side of the first lens group according to the embodiment of the present invention, the alternation of positive and negative optical powers (positive, negative, negative, positive, positive, positive) helps to balance distortion. The positive optical power of the first lens can initially focus light, and then the negative optical power lenses of the second and third lenses are used to correct distortion. Finally, the positive optical power lenses of the fourth, fifth, and sixth lenses adjust the light path again to ensure the geometric accuracy of the final image. The second lens group further optimizes distortion control through the arrangement of positive, negative, and positive optical powers, ensuring that the entire lens system can achieve the effect of low distortion. In addition, in this embodiment, by using multiple lenses, a more complex optical path design is realized, enabling the lens to better converge light and project it onto a larger imaging side without sacrificing imaging quality. Brief Description of the Drawings

[0060] Figure 1 is the structural schematic diagram of the low-distortion large target surface lens provided by Embodiment 1 of the present invention;

[0061] Figure 2 is the spot diagram of the imaging quality of the low-distortion large target surface lens provided by Embodiment 1 of the present invention;

[0062] Figure 3 is the optical distortion & field curvature diagram of the low-distortion large target surface lens provided by Embodiment 1 of the present invention;

[0063] Figure 4 is the lateral chromatic aberration diagram of the low-distortion large target surface lens provided by Embodiment 1 of the present invention;

[0064] Figure 5 is the relationship diagram between the field of view and the modulation transfer function MTF of the low-distortion large target surface lens provided by Embodiment 1 of the present invention;

[0065] Figure 6 is the relative illumination diagram of the low-distortion large target surface lens provided by Embodiment 1 of the present invention;

[0066] Figure 7 is the defocus curve diagram of the low-distortion large target surface lens provided by Embodiment 1 of the present invention at +20°C;

[0067] Figure 8It is the defocus curve graph at -40°C of the low-distortion large target surface lens provided by the first embodiment of the present utility model;

[0068] Figure 9 It is the defocus curve graph at +105°C of the low-distortion large target surface lens provided by the first embodiment of the present utility model;

[0069] Figure 10 It is the structural schematic diagram of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0070] Figure 11 It is the imaging quality spot diagram of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0071] Figure 12 It is the optical distortion & field curvature graph of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0072] Figure 13 It is the lateral chromatic aberration graph of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0073] Figure 14 It is the relationship graph between the field of view and the modulation transfer function MTF of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0074] Figure 15 It is the relative illumination graph of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0075] Figure 16 It is the defocus curve graph at +20°C of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0076] Figure 17 It is the defocus curve graph at -40°C of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0077] Figure 18 It is the defocus curve graph at +105°C of the low-distortion large target surface lens provided by the second embodiment of the present utility model;

[0078] Figure 19 It is the structural schematic diagram of the low-distortion large target surface lens provided by the third embodiment of the present utility model;

[0079] Figure 20 It is the imaging quality spot diagram of the low-distortion large target surface lens provided by the third embodiment of the present utility model;

[0080] Figure 21 It is the optical distortion & field curvature graph of the low-distortion large target surface lens provided by the third embodiment of the present utility model;

[0081] Figure 22It is the lateral chromatic aberration diagram of the low-distortion large target surface lens provided in Embodiment 3 of the present utility model;

[0082] Figure 23 It is the relationship diagram between the field of view and the modulation transfer function MTF of the low-distortion large target surface lens provided in Embodiment 3 of the present utility model;

[0083] Figure 24 It is the relative illumination diagram of the low-distortion large target surface lens provided in Embodiment 3 of the present utility model;

[0084] Figure 25 It is the defocus curve diagram of the low-distortion large target surface lens at +20 °C provided in Embodiment 3 of the present utility model;

[0085] Figure 26 It is the defocus curve diagram of the low-distortion large target surface lens at -40 °C provided in Embodiment 3 of the present utility model;

[0086] Figure 27 It is the defocus curve diagram of the low-distortion large target surface lens at +105 °C provided in Embodiment 3 of the present utility model;

[0087] Figure 28 It is the structural schematic diagram of the low-distortion large target surface lens provided in Embodiment 4 of the present utility model;

[0088] Figure 29 It is the point spread function diagram of the imaging quality of the low-distortion large target surface lens provided in Embodiment 4 of the present utility model;

[0089] Figure 30 It is the optical distortion & field curvature diagram of the low-distortion large target surface lens provided in Embodiment 4 of the present utility model;

[0090] Figure 31 It is the lateral chromatic aberration diagram of the low-distortion large target surface lens provided in Embodiment 4 of the present utility model;

[0091] Figure 32 It is the relationship diagram between the field of view and the modulation transfer function MTF of the low-distortion large target surface lens provided in Embodiment 4 of the present utility model;

[0092] Figure 33 It is the relative illumination diagram of the low-distortion large target surface lens provided in Embodiment 4 of the present utility model;

[0093] Figure 34 It is the defocus curve diagram of the low-distortion large target surface lens at +20 °C provided in Embodiment 4 of the present utility model;

[0094] Figure 35 It is the defocus curve diagram of the low-distortion large target surface lens at -40 °C provided in Embodiment 4 of the present utility model;

[0095] Figure 36It is the defocus curve graph of the low-distortion large target surface lens provided in the fourth embodiment of the present utility model at +105°C;

[0096] In the figure, LF is the first lens group; L1 is the first lens; L2 is the second lens; L3 is the third lens; L4 is the fourth lens; L5 is the fifth lens; L6 is the sixth lens; LB is the second lens group; L7 is the seventh lens; L8 is the eighth lens; L9 is the ninth lens. Specific embodiments

[0097] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present utility model. The following embodiments are used to illustrate the present utility model, but are not used to limit the scope of the present utility model.

[0098] As Figure 1 shown, the present utility model provides a low-distortion large target surface lens, which sequentially includes a first lens group LF, a diaphragm, and a second lens group FB from the object side to the image side. The first lens group FL sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 from the object side to the image side; the second lens group LB sequentially includes a seventh lens L7, an eighth lens L8, and a ninth lens L9 from the object side to the image side; the first lens L1 has a positive optical power, the second lens L2 has a negative optical power, the third lens L3 has a negative optical power, the fourth lens L4 has a positive optical power, the fifth lens L5 has a positive optical power, the sixth lens L6 has a positive optical power, the seventh lens L7 has a positive optical power, the eighth lens L8 has a negative optical power, and the ninth lens L9 has a positive optical power.

[0099] Based on the above structure, from the object side to the image side of the first lens group LF, the alternation of positive and negative optical powers (positive, negative, negative, positive, positive, positive) helps to balance distortion. The positive optical power of the first lens L1 can initially focus light, and then the negative optical power lenses of the second lens L2 and the third lens L3 are used to correct distortion. Finally, the positive optical power lenses of the fourth lens L4, the fifth lens L5, and the sixth lens L6 readjust the light path to ensure the geometric accuracy of the final image. The second lens group LB further optimizes distortion control through the arrangement of positive, negative, and positive optical powers, ensuring that the entire lens system can achieve the effect of low distortion. In addition, in this embodiment, by using multiple lenses, a more complex optical path design is realized, enabling the lens to better converge light and project it onto a larger imaging side without sacrificing imaging quality.

[0100] It should be noted that in the attached drawings, S1 is the object side of the first lens L1, S2 is the image side of the first lens L1, S3 is the object side of the second lens L2, S4 is the image side of the second lens L2, S5 is the object side of the third lens L3, S6 is the image side of the third lens L3, S7 is the object side of the fourth lens L4, S8 is the image side of the fourth lens L4 (which is also the object side of the fifth lens L5), S9 is the image side of the fifth lens L5, S10 is the object side of the sixth lens L6, S11 is the image side of the sixth lens L6, S12 is the aperture stop, S13 is the object side of the seventh lens L7, S14 is the image side of the seventh lens L7 (which is also the object side of the eighth lens L8), S15 is the image side of the eighth lens L8, S16 is the object side of the ninth lens L9, and S17 is the image side of the ninth lens L9.

[0101] Furthermore, the object side of the first lens L1 is convex in the paraxial region, its image side is concave in the paraxial region, the focal length of the first lens group LF is FL, the focal length of the first lens L1 is F1, the refractive index of the first lens L1 is N1, the Abbe number of the first lens L1 is V1, and the thickness of the first lens L1 is T1, and the following relational expressions are satisfied: 2.8 < F1 / FL < 3.2. The absolute value of the focal length of the first lens L1 is large, enabling light rays to be deflected quickly and enter subsequent propagation, which results in a large deflection angle of the light rays. The low projection height of the light rays on the first surface S3 of the second lens L2 is conducive to reducing the aperture of the second lens L2. 1.65 < N1 < 1.80, endowing it with a stronger refraction ability, which helps with a compact optical design while controlling chromatic dispersion. 50 < V1 < 75, making its chromatic dispersion smaller, which helps reduce chromatic aberration and improve the color reproduction of the image. 0.25 < T1 / FL < 0.3, making the thickness of the first lens L1 relatively thin, which helps reduce the size of the entire lens while controlling aberrations.

[0102] It should be noted that the first lens L1 in this embodiment is made of lanthanum crown glass, which has extremely high hardness and extremely low abrasion. Placed as the first lens in a low-distortion large-target surface lens, it plays a good protective role. In addition, since the positive optical power of the first lens L1 is located in the front, it can bear the distortion pressure of the system, which is the key to the system achieving low distortion.

[0103] Furthermore, the object side surface of the second lens L2 is convex in the paraxial region, and its image side surface is concave in the paraxial region. The focal length of the low-distortion large-target lens is F, the focal length of the first lens group LF is FL, the focal length of the second lens L2 is F2, the refractive index of the second lens L2 is N2, the Abbe number of the second lens L2 is V2, the thickness of the second lens L2 is T2, and the distance between the first lens L1 and the second lens L2 is d1, and the following relational expressions are satisfied: -1.3 < F2 / FL < -0.9. The second lens L2 serves to collect large-angle grazing light, allowing the light to enter subsequent propagation and playing the role of achieving a wide angle. In addition, the selection of the focal length of the second lens L2 can ensure that while the light diverges, the projection height on the object side surface S5 of the third lens L3 is relatively low. 1.70 < N2 < 1.80, enabling the second lens L2 to more effectively change the direction of the light. 45 < V2 < 60, which helps the second lens L2 control chromatic dispersion. 0.04 < T2 / FL < 0.075, which helps maintain the compactness and light weight of the lens while ensuring optical performance. 0.02 < d1 / F < 0.05. By reasonably controlling the values, it is ensured that under the premise of optimal performance, the abnormal central imaging caused by the zero distance due to the processing technology error does not occur.

[0104] Furthermore, the image side surface of the third lens L3 is concave in the paraxial region. The focal length of the low-distortion large-target lens is F, the focal length of the first lens group LF is FL, the focal length of the third lens L3 is F3, the refractive index of the third lens L3 is N3, the thickness of the third lens L3 is T3, the Abbe number of the third lens L3 is V3, and the distance between the second lens L2 and the third lens L3 is d2, and the following relational expressions are satisfied: -1 < F3 / FL < -0.25. The third lens L3 has a negative optical power and a relatively small absolute value of the focal length. When the second lens L2 limitedly improves the numerical aperture of the low-distortion large-target lens, it significantly increases the aperture value of the low-distortion large-target lens. While enhancing the light-gathering ability of the low-distortion large-target lens, the light projection height does not change sharply, allowing the propagated light to pass through the subsequent optical lenses smoothly, reducing system sensitivity, and decreasing the manufacturing, assembly, and alignment difficulty. 1.75 < N3 < 1.90, ensuring that while the second lens L2 controls the divergence of the light, the high refractive index also helps reduce the size of the entire lens system, making it more compact. 17 < V3 < 35. The Abbe number of this third lens L3 is relatively low, aiming to balance its chromatic dispersion characteristics with those of other lenses to achieve the best overall optical performance. 0.04 < T3 / FL < 0.075, which helps maintain the compactness of the lens and reduce the weight while maintaining optical performance. 0.32 < d2 / F < 0.55. By reasonably controlling the values, the processing technology of the second lens L2 can be simple and efficient, and there is enough margin for the spatial arrangement with the third lens L3.

[0105] Furthermore, the fourth lens L4 and the fifth lens L5 are cemented together to form a doublet lens, optimizing the optical performance and reducing chromatic aberration. By utilizing the dispersion characteristics of different materials to compensate each other, chromatic aberration can be significantly reduced, improving the image quality. The object side surface of the fourth lens L4 is convex in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group LF is FL, the focal length of the fourth lens L4 is F4, the refractive index of the fourth lens L4 is N4, the Abbe number of the fourth lens L4 is V4, the thickness of the fourth lens L4 is T4, and the distance between the third lens L3 and the fourth lens L4 is d3, and they satisfy the following relational expressions: 0.8 < F4 / FL < 1.2, this focal length helps to control the convergence point of light; 1.85 < N4 < 2.00, enabling it to have a strong ability to deflect light, which helps to more effectively control the light path within a limited space; 17 < V4 < 25, aiming to combine with the low dispersion characteristics of the fifth lens L5 to reduce chromatic aberration; 0.2 < T4 / FL < 0.3, helping to maintain the compactness of the lens while ensuring the mechanical strength and optical performance of the lens; 0.14 < d3 / F < 0.21, helping to control aberrations and also affecting the compactness and weight of the entire lens, as well as the difficulty of manufacturing and assembly.

[0106] Furthermore, the image side surface of the fifth lens L5 is convex in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group LF is FL, the focal length of the fifth lens L5 is F5, the refractive index of the fifth lens L5 is N5, the Abbe number of the fifth lens L5 is V5, the thickness of the fifth lens L5 is T5, and the distance between the fifth lens L5 and the sixth lens L6 is d4, and they satisfy the following relational expressions: 0.6 < F5 / FL < 1.1, which has a converging effect on light and the focal length is close to that of the first lens group LF, this helps to maintain the focused state of light in the entire lens system; 1.45 < N5 < 1.60, to effectively change the light path; 45 < V5 < 60, making its dispersion smaller, which helps to reduce chromatic aberration and improve the accuracy and clarity of image color; 0.4 < T5 / FL < 0.5, helping to ensure the mechanical stability of the lens while maintaining the necessary light control in the optical design, helping to reduce aberrations; 0.015 < d4 / F < 0.025, helping the smooth transition of light between the two lenses while controlling aberrations and ensuring that the image quality is not affected.

[0107] It should be noted that the fourth lens L4 and the fifth lens L5 are cemented with optical glue. The large difference in the Abbe numbers of the two can well correct the chromatic aberration of the system. The combined focal length of the fourth lens L4 and the fifth lens L5 is a positive optical power and the absolute value is small, ensuring that the system length will not be too long and affecting the compatibility with other platforms. In addition, the relatively long distance between S7 - S9 ensures that the deflection angle of light during propagation is not too large, causing a sharp change in image quality.

[0108] Further, the object side of the sixth lens L6 is convex in the paraxial region, and its image side is concave in the paraxial region. The focal length of the low-distortion large target surface lens is F, the focal length of the first lens group LF is FL, the focal length of the sixth lens L6 is F6, the refractive index of the sixth lens L6 is N6, the Abbe number of the sixth lens L6 is V6, the thickness of the sixth lens L6 is T6, and the distance between the sixth lens L6 and the diaphragm is d5, and the following relational expressions are satisfied: 7.5 < F6 / FL < 10, which helps to control the light path and reduce aberrations; 1.45 < N6 < 1.65, which can bend light more effectively but may also introduce chromatic aberration at the same time; 60 < V6 < 80, making it have less dispersion; 0.2 < T6 / FL < 0.3, avoiding mechanical problems or optical defects caused by being too thick or too thin; 0.065 < d5 / F < 0.085, reasonably controlling the value, ensuring that there is enough edge break margin and clear aperture on the second surface S11 of the sixth lens L6, and the aperture size of the diaphragm surface can be well controlled during the structural design, so as to effectively ensure the true accuracy of the working F# of the system.

[0109] It should be noted that the sixth lens L6 uses glass with the ratio of material property parameters dn / dt < -5.0*E -6 to ensure the high and low temperature performance. The curvature of the second optical surface S11 of the sixth lens L6 is positive and bends towards the diaphragm surface, which helps to correct the spherical aberration of the low-distortion large target surface lens.

[0110] Placing the diaphragm at a position far from the first surface (i.e., S1) of the optical path system combined by the above multiple lenses is beneficial to reducing the aberrations of the entire system.

[0111] Further, the seventh lens L7 and the eighth lens L8 are cemented together to form a doublet lens, which can effectively reduce chromatic aberration and other aberrations, and at the same time enhance the overall performance of the optical system. The image side of the seventh lens L7 is convex in the paraxial region. The focal length of the low-distortion large target surface lens is F, the focal length of the second lens group LB is FB, the focal length of the seventh lens L7 is F7, the refractive index of the seventh lens L7 is N7, the Abbe number of the seventh lens L7 is V7, the thickness of the seventh lens L7 is T7, and the distance between the diaphragm and the seventh lens L7 is d6, and the following relational expressions are satisfied: 0.25 < F7 / FB < 0.5, which helps to effectively converge light while controlling aberrations; 1.5 < N7 < 1.65, which helps to control the light path and reduce aberrations at the same time; 65 < V7 < 70, which helps to reduce chromatic aberration and improve image quality; 0.15 < T7 / FB < 0.25, ensuring that the thickness of the lens is appropriate, which can not only ensure the optical performance but also not introduce additional aberrations due to being too thick; 0.035 < d6 / F < 0.055, which helps to control the incident angle of light, reduce aberrations, and at the same time ensure that the light can smoothly transition to the next lens group.

[0112] It should be noted that the seventh lens L7 uses ultra-low dispersion glass with a dn / dt ratio of the material performance parameters < -5.0*E -6 to ensure the high and low temperature performance. At the same time, it is glued with the eighth lens L8 using optical glue to effectively correct the chromatic aberration of the system. The curvature of the first optical surface of the seventh lens L7, i.e., S13, is negative and bends towards the diaphragm surface, which helps to correct the spherical aberration of this low distortion large target surface lens.

[0113] Furthermore, the object side of the eighth lens L8 is concave near the axis, and its image side is convex near the axis. The focal length of the low distortion large target surface lens is F, the focal length of the second lens group LB is FB, the focal length of the eighth lens L8 is F8, the refractive index of the eighth lens L8 is N8, the Abbe number of the eighth lens L8 is V8, the thickness of the eighth lens L8 is T8, and the distance between the eighth lens L8 and the ninth lens L9 is d8, and the following relationships are satisfied: -0.65 < F8 / FB < 0.43, which helps to balance the convergence and divergence of light and control aberrations; 1.70 < N8 < 1.85, making the deflection ability of the eighth lens L8 for light stronger, which helps to control the light path and reduce aberrations; 17 < V8 < 35, which is used in the doublet lens to cooperate with the seventh lens L7 to reduce chromatic aberration; 0.03 < T8 / FB < 0.065, ensuring that the thickness of the lens is sufficient to support its optical performance, and at the same time, no additional aberrations or weights are introduced due to excessive thickness; 0.31 < d8 / F < 0.36, which helps the smooth transition of light between the two lenses, reduces aberrations, and ensures that light can be transmitted to the next lens along an ideal path.

[0114] It should be noted that the seventh lens L7 and the eighth lens L8 are glued with optical glue. The combined focal length of the seventh lens L7 and the eighth lens L8 has a positive optical power and a large absolute value, ensuring the back intercept length of the optical system, i.e., the distance of S17 - S18, and ensuring that the far and near focusing ranges do not interfere with the mechanical structure.

[0115] Further, the object side of the ninth lens L9 is convex in the paraxial region, and its image side is convex in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the second lens group LB is FB, the focal length of the ninth lens L9 is F9, the refractive index of the ninth lens L9 is N9, the Abbe number of the ninth lens L9 is V9, the thickness of the ninth lens L9 is T9, and the distance between the ninth lens L9 and the imaging surface is d8, and the following relational expressions are satisfied: 1.55 < F9 / FB < 2.10, which helps to control the convergence of light and reduce aberration; 1.65 < N9 < 1.80, which helps to reduce aberration and ensure that light can be focused in the expected manner; 45 < V9 < 65, which helps to reduce chromatic aberration and ensure that light of different wavelengths can be focused at the same point simultaneously, thereby improving image quality; 0.15 < T9 / FB < 0.25, which ensures that the thickness of the lens is suitable for its optical function, neither resulting in insufficient mechanical strength due to being too thin nor introducing additional aberration due to being too thick; 0.63 < d9 / F < 0.75, which helps to reduce aberration and ensure the clarity of the image.

[0116] The ninth lens L9 in this embodiment functions to control the imaging target surface of the low distortion large target surface lens to match the CCD, not be too large, and enable the CRA of each field of view of the low distortion large target surface lens to correspond well to the CCD. At the same time, it reduces the light propagation length and controls the overall length of the assembly of each lens combination.

[0117] The following will illustrate the low distortion large target surface lens of the present invention with examples. The symbols recorded in each example are as follows. The unit of the spherical radius and the lens interval is mm.

[0118] Combined with Figures 1 to 9 , Table 1 shows the design data of the low distortion large target surface lens according to the first embodiment of the present invention.

[0119]

Table 1

[0120] Surface number Surface type Spherical radius R Interval Nd Vd S1 Spherical surface 11.812 2.500 1.759 56.685 S2 Spherical surface 25.564 0.200 S3 Spherical surface 7.200 0.600 1.755 54.322 S4 Spherical surface 3.779 2.157 S5 Spherical surface 61.086 0.600 1.827 26.784 S6 Spherical surface 3.194 0.870 S7 Spherical surface 8.835 2.000 1.943 18.896 S8 Spherical surface -81.567 3.800 1.589 58.041 S9 Spherical surface -4.615 0.100 S10 Spherical surface 4.252 2.000 1.583 69.342 S11 Spherical surface 3.520 0.375 S12 (diaphragm) Spherical surface Infinity 0.240 S13 Spherical surface -109.503 2.000 1.593 69.342 S14 Spherical surface -2.357 0.600 1.785 27.720 S15 Spherical surface -5.648 1.718 S16 Spherical surface 36.585 2.000 1.743 56.833 S17 Spherical surface -24.251 3.310 S18 (image plane) Image plane Infinity

[0121] Among them, the equivalent focal length F of the optical system is 4.95 mm, the working F# is 2.5, the total length defined as the system length from S1 to S18 is less than 25.5 mm, DFOV is 80°, the imaging circle diameter is D8.2 mm, the absolute value of the maximum optical distortion is less than 1.4%, and the maximum outer diameter of the first lens L1 is less than D14 mm.

[0122] Among them, Figure 2 is the spot diagram of the imaging quality of the first embodiment. The center of its spot diagram of the imaging quality is smaller than the pixel size of the CCD used for 4K picture quality, and the spot diagrams of the imaging quality of the peripheral fields of view also meet the requirements.

[0123] Figure 3It is the optical distortion & field curvature diagram of Embodiment 1, and the resulting field curvature is less than 0.05 mm. The field curvatures of the off-axis meridional and sagittal planes are effectively corrected.

[0124] Figure 4 It is the lateral chromatic aberration diagram of Embodiment 1. The maximum lateral chromatic aberration is less than 4 μm. In the wavelength range of 436 nm to 656 nm, the blue-violet edge overflow phenomenon of the system can be effectively suppressed, making the imaging picture closer to the natural light color.

[0125] Figure 5 It is the relationship diagram between the field of view and the transfer function MTF of Embodiment 1. The fluctuations of the transfer function MTF in each field of view are not significant. It can be seen that the resolution capabilities of each field of view of the system are consistent, all meeting the requirements of 4K imaging, and the high and low frequencies of the optical system are relatively concentrated, corresponding to excellent resolution capabilities and contrast of the system.

[0126] Figure 6 It is the relative illumination diagram of Embodiment 1. The illumination of the maximum field of view is greater than 30%, meeting the usage requirements. There will be no vignetting in the picture, affecting the usage efficiency of the maximum imaging circle, and fully releasing the performance of the system.

[0127] Figure 7 It is the defocus curve diagram of +20 °C of Embodiment 1. The MTF value of the central field of view is greater than 0.8, the curve is concentrated, and the MTF of each field of view is consistent.

[0128] Figure 8 It is the defocus curve diagram of -40 °C of Embodiment 1. In the environment of low temperature -40 °C, compared with Figure 7 it is considered that the defocus amount of the system is small in the low-temperature environment and does not affect the picture clarity.

[0129] Figure 9 It is the defocus curve diagram of +105 °C of Embodiment 1. In the environment of high temperature +105 °C, compared with Figure 7 it is considered that the defocus amount of the system is small in the high-temperature environment and does not affect the picture clarity.

[0130] Combined with Figures 10 to 18 , Table 2 shows the design data of the low-distortion large target surface lens of the second embodiment of the present invention.

[0131]

Table 2

[0132]

[0133]

[0134] The implementation parameters of Embodiment 2 vary little within the value ranges of L1-L9 optical lenses and T, d of S1-S18. These variations can be seen by those skilled in the art from the attached pictures and tables.

[0135] Combined with Figures 19 to 27 , Table 3 shows the design data of the low-distortion large target surface lens of the third embodiment of the present invention.

[0136]

Table 3

[0137] Surface number Surface type Spherical radius R Interval Nd Vd S1 Spherical surface 13.537 2.500 1.769 52.685 S2 Spherical surface 32.566 0.200 S3 Spherical surface 7.777 0.600 1.715 52.322 S4 Spherical surface 3.746 2.212 S5 Spherical surface -67.899 0.600 1.827 23.784 S6 Spherical surface 3.690 0.855 S7 Spherical surface 9.453 2.000 2.001 25.426 S8 Spherical surface -26.675 4.400 1.519 58.041 S9 Spherical surface -4.691 0.100 S10 Spherical surface 4.252 2.000 1.622 52.539 S11 Spherical surface 4.252 0.332 S12 (diaphragm) Spherical surface Infinity 0.651 S13 Spherical surface -67.969 2.400 1.533 66.342 S14 Spherical surface -2.178 0.600 1.745 23.720 S15 Spherical surface -7.625 0.637 S16 Spherical surface 26.846 2.000 1.745 54.322 S17 Spherical surface -18.392 3.335 S18 (image plane) Image plane Infinity

[0138] The implementation parameters of the third embodiment vary little within the value ranges of T and d of the L1-L9 optical lenses and S1-S18, and these variations can be seen by those skilled in the art from the attached pictures and tables.

[0139] Combined with Figures 28 to 36 , Table 4 shows the design data of the low-distortion large target surface lens of the fourth embodiment of the present invention.

[0140]

Table 4

[0141] Surface number Surface type Spherical radius R Interval Nd Vd S1 Spherical surface 13.335 2.400 1.749 54.685 S2 Spherical surface 31.909 0.200 S3 Spherical surface 6.400 0.600 1.785 58.322 S4 Spherical surface 3.619 2.187 S5 Spherical surface 85.786 0.600 1.827 27.784 S6 Spherical surface 3.311 0.878 S7 Spherical surface 9.248 2.000 1.953 18.896 S8 Spherical surface -56.929 3.900 1.529 52.041 S9 Spherical surface -4.337 0.100 S10 Spherical surface 4.060 2.000 1.543 68.342 S11 Spherical surface 3.652 0.376 S12 (diaphragm) Spherical surface Infinity 0.294 S13 Spherical surface -102.551 1.900 1.583 68.342 S14 Spherical surface -2.270 0.600 1.785 23.720 S15 Spherical surface -6.289 1.741 S16 Spherical surface 34.913 2.000 1.743 56.833 S17 Spherical surface -21.368 3.334 S18 (image plane) Image plane Infinity

[0142] The implementation parameters of the fourth embodiment vary little within the value ranges of T and d of the L1-L9 optical lenses and S1-S18, and these variations can be seen by those skilled in the art from the attached pictures and tables.

[0143] In summary, the embodiments of the present invention provide a low-distortion large target surface lens. The selected lens materials and their distribution positions enable the incident light to transition smoothly without generating excessive light deflection angles, resulting in a low sensitivity of the overall light system and a large tolerance redundancy, greatly improving the yield of actual production and further reducing costs.

[0144] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and substitutions can be made, and these improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A low-distortion large target surface lens, characterized in that, It sequentially includes a first lens group, a diaphragm, and a second lens group from the object side to the image side. The first lens group sequentially includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens from the object side to the image side; the second lens group sequentially includes a seventh lens, an eighth lens, and a ninth lens from the object side to the image side; the first lens has a positive optical power, the second lens has a negative optical power, the third lens has a negative optical power, the fourth lens has a positive optical power, the fifth lens has a positive optical power, the sixth lens has a positive optical power, the seventh lens has a positive optical power, the eighth lens has a negative optical power, and the ninth lens has a positive optical power.

2. The low distortion large target surface lens according to claim 1, characterized in that, The object side surface of the first lens is convex in the paraxial region, and its image side surface is concave in the paraxial region. The focal length of the first lens group is FL, the focal length of the first lens is F1, the refractive index of the first lens is N1, the Abbe number of the first lens is V1, the thickness of the first lens is T1, and the following relational expressions are satisfied: 2.8 < F1 / FL < 3.2; 1.65<N1<1.80； 50<V1<75； 0.25 < T1 / FL < 0.

3.

3. The low distortion large target surface lens according to claim 1, characterized in that, The object side surface of the second lens is convex in the paraxial region, and its image side surface is concave in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the second lens is F2, the refractive index of the second lens is N2, the Abbe number of the second lens is V2, the thickness of the second lens is T2, and the distance between the first lens and the second lens is d1, and the following relational expressions are satisfied: -1.3 < F2 / FL < -0.9; 1.70<N2<1.80； 45<V2<60； 0.04 < T2 / FL < 0.075; 0.02 < d1 / F < 0.

05.

4. The low distortion large target surface lens according to claim 1, wherein, The image side surface of the third lens is concave in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the third lens is F3, the refractive index of the third lens is N3, the thickness of the third lens is T3, the Abbe number of the third lens is V3, and the distance between the second lens and the third lens is d2, and the following relational expressions are satisfied: -1 < F3 / FL < -0.25; 1.75<N3<1.90； 17<V3<35； 0.04 < T3 / FL < 0.075; 0.32 < d2 / F < 0.

55.

5. The low-distortion large target surface lens according to claim 1, wherein The fourth lens and the fifth lens are cemented together to form a doublet lens. The object side surface of the fourth lens is convex in the paraxial region. The focal length of the low distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the fourth lens is F4, the refractive index of the fourth lens is N4, the Abbe number of the fourth lens is V4, the thickness of the fourth lens is T4, and the distance between the third lens and the fourth lens is d3, and the following relational expressions are satisfied: 0.8 < F4 / FL < 1.2; 1.85<N4<2.00； 17<V4<25； 0.2 < T4 / FL < 0.3; 0.14 < d3 / F < 0.

21.

6. The low distortion large target surface lens according to claim 5, characterized in that The image side of the fifth lens is convex in the paraxial region. The focal length of the low-distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the fifth lens is F5, the refractive index of the fifth lens is N5, the Abbe number of the fifth lens is V5, the thickness of the fifth lens is T5, and the distance between the fifth lens and the sixth lens is d4, and the following relational expressions are satisfied: 0.6 < F5 / FL < 1.1; 1.45<N5<1.60； 45<V5<60； 0.4 < T5 / FL < 0.5; 0.015 < d4 / F < 0.

025.

7. The low distortion large target surface lens according to claim 1, wherein The object side of the sixth lens is convex in the paraxial region, and its image side is concave in the paraxial region. The focal length of the low-distortion large target surface lens is F, the focal length of the first lens group is FL, the focal length of the sixth lens is F6, the refractive index of the sixth lens is N6, the Abbe number of the sixth lens is V6, the thickness of the sixth lens is T6, and the distance between the sixth lens and the diaphragm is d5, and the following relational expressions are satisfied: 7.5 < F6 / FL < 10; 1.45<N6<1.65； 60<V6<80； 0.2 < T6 / FL < 0.3; 0.065 < d5 / F < 0.

085.

8. The low-distortion large target surface lens according to claim 1, wherein The seventh lens and the eighth lens are cemented to form a doublet lens. The image side of the seventh lens is convex in the paraxial region. The focal length of the low-distortion large target surface lens is F, the focal length of the second lens group is FB, the focal length of the seventh lens is F7, the refractive index of the seventh lens is N7, the Abbe number of the seventh lens is V7, the thickness of the seventh lens is T7, and the distance between the diaphragm and the seventh lens is d6, and the following relational expressions are satisfied: 0.25 < F7 / FB < 0.5; 1.5<N7<1.65； 65<V7<70； 0.15 < T7 / FB < 0.25; 0.035 < d6 / F < 0.

055.

9. The low distortion large target surface lens according to claim 8, characterized in that The object side of the eighth lens is concave in the paraxial region, and its image side is convex in the paraxial region. The focal length of the low-distortion large target surface lens is F, the focal length of the second lens group is FB, the focal length of the eighth lens is F8, the refractive index of the eighth lens is N8, the Abbe number of the eighth lens is V8, the thickness of the eighth lens is T8, and the distance between the eighth lens and the ninth lens is d8, and the following relational expressions are satisfied: -0.65 < F8 / FB < 0.43; 1.70<N8<1.85； 17<V8<35； 0.03 < T8 / FB < 0.065; 0.31 < d8 / F < 0.

36.

10. The low distortion large target surface lens according to claim 1, characterized in that, The object side of the ninth lens is convex in the paraxial region, and its image side is convex in the paraxial region. The focal length of the low-distortion large target surface lens is F, the focal length of the second lens group is FB, the focal length of the ninth lens is F9, the refractive index of the ninth lens is N9, the Abbe number of the ninth lens is V9, the thickness of the ninth lens is T9, and the distance between the ninth lens and the imaging surface is d9, and the following relational expressions are satisfied: 1.55 < F9 / FB < 2.10; 1.65<N9<1.80； 45<V9<65； 0.15 < T9 / FB < 0.25; 0.63 < d9 / F < 0.75.

Images