Lens

Abstract

The present invention relates to a lens which, in the direction from the object side to the image side along the optical axis, sequentially includes a first lens (1) with a negative optical power, a second lens (2) with a negative optical power, a third lens (3) with a positive optical power, a fourth lens (4) with a negative optical power, a fifth lens (5) with a positive optical power, a sixth lens (6) with a positive optical power, a seventh lens (7) with a negative optical power, and an eighth lens (8) with a positive optical power; the first lens (1), the second lens (2), the seventh lens (7), and the eighth lens (8) are plastic lenses, and at least three of the third lens (3), the fourth lens (4), the fifth lens (5), and the sixth lens (6) are glass lenses. The lens of the present invention has the characteristics of a large aperture and day-night confocal.

Description

Technical Field

[0001] The present invention relates to the technical field of optical system and device design, and particularly to a lens. Background Art

[0002] With the rapid development of technology, higher requirements have been put forward for optical lenses in various industries in aspects such as resolution, day-night confocal, and high-low temperature confocal. Generally, ordinary cameras do not have the day-night confocal function and are only suitable for places with good lighting conditions. However, in low-light conditions such as at night with low brightness or in dim light, the imaging effect is poor, or auxiliary light sources such as infrared fill lights and flashlights need to be added, resulting in a complex optical system structure and large volume, and at the same time, the imaging effect cannot be effectively guaranteed. In this case, developing a large-aperture lens that can ensure the imaging effect and has a simple structure under low-light conditions has become one of the current hotspots. Summary of the Invention

[0003] The purpose of the present invention is to solve the above problems and provide a lens with a large aperture.

[0004] To achieve the above purpose, the present invention provides a lens, which sequentially includes a first lens with a negative focal power, a second lens with a negative focal power, a third lens with a positive focal power, a fourth lens with a negative focal power, a fifth lens with a positive focal power, a sixth lens with a positive focal power, a seventh lens with a negative focal power, and an eighth lens with a positive focal power along the optical axis from the object side to the image side direction;

[0005] The first lens, the second lens, the seventh lens, and the eighth lens are plastic lenses, and at least three of the third lens, the fourth lens, the fifth lens, and the sixth lens are glass lenses.

[0006] According to an embodiment of the present invention, the lens further includes a diaphragm, and the diaphragm is located on the image side surface of the third lens, or between the third lens and the fourth lens, or on the object side surface of the fourth lens.

[0007] According to an embodiment of the present invention, the fourth lens and the fifth lens form a cemented lens group with a positive focal power.

[0008] According to an aspect of the present invention, along the object side to the image side direction, the first lens is a convex-concave lens, the second lens is a concave-concave lens or a concave-convex lens, the third lens is a convex-convex lens or a concave-convex lens, the fourth lens is a concave-concave lens or a convex-concave lens, the seventh lens is a concave-concave lens or a convex-concave lens, and the fifth lens, the sixth lens, and the eighth lens are all convex-convex lenses.

[0009] According to one aspect of the present invention, at least one of the third lens, the fourth lens, the fifth lens, and the sixth lens is a low-dispersion glass lens with an Abbe number Vd≥60.

[0010] According to one aspect of the present invention, the refractive index Nd≥1.6 of at least two of the first lens, the second lens, the third lens, the seventh lens, and the eighth lens.

[0011] According to one aspect of the present invention, the effective focal length of the first lens to the third lens is f1, and the effective focal length of the lens is f, satisfying the relationship: -11≤f1 / f≤-1.

[0012] According to one aspect of the present invention, the effective focal length of the fourth lens to the eighth lens is f2, and the effective focal length of the lens is f, satisfying the relationship: 1.6≤f2 / f≤2.

[0013] According to one aspect of the present invention, the distance from the center of the image side of the eighth lens to the image plane of the lens is d, and the distance from the object side of the first lens to the image plane of the lens is D, satisfying the relationship: d / D≥0.18.

[0014] According to one aspect of the present invention, the Abbe numbers of the fourth lens and the fifth lens are v4 and v5 respectively, satisfying the relationship: |v4 - v5|≥30.

[0015] According to one aspect of the present invention, the relative aperture FNO of the lens≤1.2.

[0016] For the lens of the present invention, by optimizing the positive and negative optical powers of each lens, the aberration is effectively corrected. Then, combined with the glass-plastic hybrid structure, the production cost is reduced. The infrared defocus amount of the lens of the present invention is within 0.006mm, and it can achieve day-night confocal (visible light and infrared light confocal), realize the large aperture of F1.0 of the lens, and at the same time, the resolution reaches the requirements of a 5M lens, ensuring high resolution under a large aperture. At the same time, the lens of the present invention can achieve no defocus within the temperature range of -40°C to 80°C, overcoming the difficulty that the plastic aspheric lens is prone to focus drift in high and low temperature environments due to its large expansion coefficient. In addition, the lens of the present invention includes a total of 8 lenses, with a small volume, and the total length of the lens is within 22.2mm. At the same time, the single part and assembly tolerance of the lens of the present invention are good, and it has good manufacturability. Brief Description of the Drawings

[0017] Figure 1 Schematic diagram showing the structure of the lens according to Embodiment 1 of the present invention;

[0018] Figure 2 Schematic diagram showing the MTF of the lens of Embodiment 1;

[0019] Figure 3 Schematically showing the Through-Focus-MTF graph of the lens in Example 1 with a frequency of 120 lp / mm;

[0020] Figure 4 Schematically showing the Through-Focus-MTF graph of the lens in Example 1 with an infrared frequency of 120 lp / mm;

[0021] Figure 5 Schematically showing the ray fan graph of the lens in Example 1;

[0022] Figure 6 Schematically showing the structural schematic diagram of the lens according to Example 2 of the present invention;

[0023] Figure 7 Schematically showing the MTF graph of the lens in Example 2;

[0024] Figure 8 Schematically showing the Through-Focus-MTF graph of the lens in Example 2 with a frequency of 120 lp / mm;

[0025] Figure 9 Schematically showing the Through-Focus-MTF graph of the lens in Example 2 with an infrared frequency of 120 lp / mm;

[0026] Figure 10 Schematically showing the ray fan graph of the lens in Example 2;

[0027] Figure 11 Schematically showing the structural schematic diagram of the lens according to Example 3 of the present invention;

[0028] Figure 12 Schematically showing the MTF graph of the lens in Example 3;

[0029] Figure 13 Schematically showing the Through-Focus-MTF graph of the lens in Example 3 with a frequency of 120 lp / mm;

[0030] Figure 14 Showing the Through-Focus-MTF graph of the lens in Example 3 with an infrared frequency of 120 lp / mm;

[0031] Figure 15 Schematically showing the ray fan graph of the lens in Example 3;

[0032] Figure 16 Schematically showing the structural schematic diagram of the lens according to Example 4 of the present invention;

[0033] Figure 17Schematic MTF diagram of the lens of Example 4;

[0034] Figure 18 Schematic Through-Focus-MTF diagram of the lens of Example 4 with a frequency of 120 lp / mm;

[0035] Figure 19 Through-Focus-MTF diagram of the lens of Example 4 with an infrared frequency of 120 lp / mm;

[0036] Figure 20 Schematic ray fan diagram of the lens of Example 4;

[0037] Figure 21 Schematic structural diagram of the lens according to Example 5 of the present invention;

[0038] Figure 22 Schematic MTF diagram of the lens of Example 5;

[0039] Figure 23 Schematic Through-Focus-MTF diagram of the lens of Example 5 with a frequency of 120 lp / mm;

[0040] Figure 24 Through-Focus-MTF diagram of the lens of Example 5 with an infrared frequency of 120 lp / mm;

[0041] Figure 25 Schematic ray fan diagram of the lens of Example 5. Detailed implementation manners

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for use in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0043] The present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation manners. The implementation manners cannot be elaborated one by one here, but the implementation manners of the present invention are not limited to the following implementation manners.

[0044] As Figure 1As shown in the figure, the present invention provides a lens which, along the optical axis from the object side to the image side, sequentially includes a first lens 1 with a negative optical power, a second lens 2 with a negative optical power, a third lens 3 with a positive optical power, a fourth lens 4 with a negative optical power, a fifth lens 5 with a positive optical power, a sixth lens 6 with a positive optical power, a seventh lens 7 with a negative optical power, and an eighth lens 8 with a positive optical power. And the first lens 1, the second lens 2, the seventh lens 7, and the eighth lens 8 are plastic lenses, and at least three of the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are glass lenses.

[0045] The lens of the present invention comprises a total of 8 lenses and has a small volume. By reasonably arranging the optical powers of each lens and adopting a scheme of using plastic lenses and glass lenses in combination, the lens of the present invention can achieve the function of day and night confocal, while achieving a large aperture, and the resolution reaches the requirements of a 5M lens. In addition, the combination of plastic lenses and glass lenses is also beneficial to reducing the production cost and ensuring no defocus within the range of high and low temperatures.

[0046] The lens of the present invention further includes a diaphragm S, and the diaphragm S is located on the image side surface of the third lens 3, or between the third lens 3 and the fourth lens 4, or on the object side surface of the fourth lens 4.

[0047] In the present invention, the fourth lens 4 and the fifth lens 5 form a cemented lens group with a positive optical power.

[0048] According to an embodiment of the present invention, along the object side to the image side direction, the first lens 1 is a convex-concave lens, the second lens 2 is a concave-concave lens or a concave-convex lens, the third lens 3 is a convex-convex lens or a concave-convex lens, the fourth lens 4 is a concave-concave lens or a convex-concave lens, the seventh lens 7 is a concave-concave lens or a convex-concave lens, and the fifth lens 5, the sixth lens 6, and the eighth lens 8 are all convex-convex lenses.

[0049] Among them, at least one of the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 is a low-dispersion glass lens with an Abbe number Vd≥60. At least two of the first lens 1, the second lens 2, the third lens 3, the seventh lens 7, and the eighth lens 8 have a refractive index Nd≥1.6.

[0050] For the lens of the present invention, the effective focal length of the first lens 1 to the third lens 3 is f1, and the effective focal length of the lens is f, satisfying the relationship: -11≤f1 / f≤-1. The effective focal length of the fourth lens 4 to the eighth lens 8 is f2, satisfying the relationship: 1.6≤f2 / f≤2.

[0051] For the lens of the present invention, the distance from the image side center of the eighth lens 8 to the image plane of the lens is d, and the distance from the object side of the first lens 1 to the image plane of the lens is D, satisfying the relationship: d / D≥0.18. The Abbe numbers of the fourth lens 4 and the fifth lens 5 are v4 and v5 respectively, satisfying the relationship: |v4 - v5|≥30.

[0052] The relative aperture FNO of the lens of the present invention is ≤1.2.

[0053] The plastic lens of the present invention is an aspherical lens. For the lens of the present invention, all aspherical surfaces satisfy:

[0054]

[0055] In the formula, z is the axial distance from the vertex of the curved surface at the position with a height h perpendicular to the optical axis along the optical axis direction; c represents the curvature at the vertex of the aspherical surface; k is the conic coefficient; A4, A6, A8, A10, A12, A14, A16··· respectively represent the aspherical coefficients of the fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order, sixteenth order···

[0056] In summary, the lens of the present invention is set according to the above limitations. By optimizing the positive and negative optical powers of each lens, the aberration is effectively corrected. Then, combined with the glass-plastic hybrid structure, the production cost is reduced, and the infrared defocus amount of the lens of the present invention is within 0.006 mm, which can achieve day-night confocal (visible light and infrared light confocal), realize the F1.0 large aperture of the lens, and at the same time the resolution meets the requirements of a 5M lens, ensuring high resolution under the large aperture. At the same time, the lens of the present invention can achieve no defocus within the temperature range of -40°C to 80°C, overcoming the difficulty that the plastic aspherical lens is prone to focus drift in high and low temperature environments due to its large expansion coefficient. In addition, the lens of the present invention includes a total of 8 lenses, with a small volume and the total length of the lens within 22.2 mm. At the same time, the single part and assembly tolerance of the lens of the present invention are good, and it has good manufacturability.

[0057] The following gives 5 specific embodiments according to the above settings of the present invention to specifically illustrate the lens according to the present invention. The lens of the present invention includes a total of 8 lenses, among which the fourth lens and the fifth lens 5 form a cemented lens group. Together with the filter and the imaging surface, there are a total of 18 optical surfaces. When the diaphragm S is located between the third lens 3 and the fourth lens 4, an additional diaphragm surface is added. Therefore, the fixed-focus lens of the present invention includes at most 19 optical surfaces. For the convenience of description, the 19 optical surfaces are numbered as S1 - S19 as needed.

[0058] The data of the five groups of embodiments are as follows in Table 1:

[0059] Conditional Implementation Case 1 Implementation Case 2 Implementation Case 3 Implementation Case 4 Implementation Case 5 -11 ≤ f1 / f ≤ -1 -10.95 -1.46 -2.39 -4.42 -3.2 1.6 ≤ f2 / f ≤ 2 1.93 1.65 1.93 1.81 1.85 d / D ≥ 0.18 0.21 0.23 0.18 0.24 0.21 |v4 - v5| ≥ 30 30.2 42.5 66.62 35.8 69.6

[0060] Table 1

[0061] Embodiment 1:

[0062] Figure 1 It schematically shows a lens structure diagram according to Embodiment 1 of the present invention.

[0063] In this embodiment, the total lens length TTL = 22.2 mm, FN0 = 1.0, the aperture S is located between the third lens 3 and the fourth lens 4. The third lens 3 is a plastic lens, the fourth lens 4 is a glass lens, the fifth lens 5 and the sixth lens 6 are low-dispersion glass lenses, and the refractive indices Nd of the third lens 3 and the seventh lens 7 are ≥ 1.6.

[0064] The following Table 2 lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0065]

[0066]

[0067] Table 2

[0068] Table 3 lists the aspherical coefficients of each aspherical lens in this embodiment. K is the conic constant of the surface, and A, B, C, D, E, and F are the aspherical coefficients of the fourth, sixth, eighth, tenth, twelfth, and fourteenth orders respectively.

[0069] Surface Serial Number K A B C D E S1 6.915E+00 -3.992E-04 0.000E+00 0.000E+00 0.000E+00 0.000E+00 S2 -8.996E-01 -1.356E-04 1.997E-04 -2.904E-05 1.932E-06 6.0414E-8 S3 -8.116E-01 1.132E-02 -4.609E-04 2.410E-05 -5.411E-07 1.7939E-08 S4 3.364E-01 8.392E-03 -9.941E-06 2.561E-06 -8.044E-09 -3.0668E-10 S5 -3.686E-02 -2.720E-03 1.979E-04 -1.273E-05 3.254E-07 -1.1087E-08 S6 -1.521E+00 -2.565E-03 1.772E-04 -1.035E-05 2.199E-07 1.1245E-08 S13 4.759E-01 -4.752E-03 2.280E-04 -7.637E-06 9.158E-08 2.7486E-09 S14 -1.307E-02 -6.073E-03 2.338E-04 -9.156E-06 1.096E-07 -2.9152E-08 S15 1.476E+00 -1.200E-03 -6.095E-05 1.088E-06 -2.608E-09 -8.0993E-09 S16 1.583E-01 9.726E-04 -2.997E-05 3.319E-07 1.847E-10 3.8623E-10

[0070] Table 3

[0071] Figures 2 - 5 They respectively schematically show the MTF diagram of the lens of Embodiment 1, the Through-Focus-MTF diagram with a frequency of 120 lp / mm, the Through-Focus-MTF diagram with an outer frequency of 120 lp / mm, and the ray fan diagram. It can be known from the accompanying drawings that for the lens obtained according to Embodiment 1 of the present invention, the aperture number can reach F1.0. At the same time, the infrared defocus amount of the lens is within 0.006 mm, and it can achieve day and night confocal, and there is no defocus within the temperature range of -40°C to 80°C.

[0072] Embodiment 2:

[0073] Figure 6 It schematically shows a lens structure diagram according to Embodiment 2 of the present invention.

[0074] In this embodiment, the total lens length TTL = 20.8 mm, FN0 = 1.2, the aperture stop S is located between the third lens 3 and the fourth lens 4. The third lens 3, the fourth lens 4 and the fifth lens are glass lenses, the sixth lens 6 is a plastic lens, and the third lens 3 and the fifth lens are low-dispersion glass lenses. The refractive indices Nd of the third lens 3 and the seventh lens 7 are ≥1.6.

[0075] The following Table 4 lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0076]

[0077]

[0078] Table 4

[0079] Table 5 lists the aspheric coefficients of each aspheric lens in this embodiment. K is the conic constant of the surface, and A, B, C, D, E, and F are the aspheric coefficients of the fourth, sixth, eighth, tenth, twelfth, and fourteenth orders respectively.

[0080] Surface Serial Number K A B C D E S1 0.0000E+00 1.3253E-03 -3.3478E-05 4.0058E-07 -5.2709E-10 -1.1245E-11 S2 0.0000E+00 -1.7862E-03 -1.3237E-04 7.1352E-06 2.6398E-06 -2.7486E-07 S3 -5.5614E-01 9.5534E-03 -9.4782E-04 -5.8180E-05 -2.0223E-06 2.9152E-08 S4 8.6906E+00 -1.1670E-02 -5.5974E-04 1.1557E-05 1.9681E-06 -8.9993E-08 S11 -2.4803E-01 -1.2252E-03 -2.6473E-05 -6.1043E-06 2.6688E-07 -1.8623E-09 S12 -7.2526E+00 3.5416E-03 5.5438E-05 3.0964E-06 -2.9056E-07 1.0441E-08 S13 -1.8828E+01 -1.8240E-03 -1.7410E-04 -9.9725E-06 1.2650E-07 -9.0414E-10 S14 -4.5645E-01 5.3961E-03 4.5219E-04 -1.6513E-05 -9.3842E-09 -1.7939E-08 S15 -4.3720E-01 -5.7458E-03 -3.9654E-04 3.4543E-06 -5.1092E-07 -2.0668E-08 S16 -2.6887E+00 1.9492E-03 -1.0917E-04 1.4904E-05 -8.7973E-07 1.1087E-08

[0081] Table 5

[0082] Figures 7 - 10 Schematically show the MTF graph of the lens of Embodiment 2, the Through-Focus-MTF graph with a frequency of 120 lp / mm, the Through-Focus-MTF graph with an outer frequency of 120 lp / mm, and the ray fan graph. It can be known from the accompanying drawings that for the lens obtained according to Embodiment 2 of the present invention, the aperture number can reach F1.0. At the same time, the infrared defocus amount of the lens is within 0.006 mm, and it can achieve day and night confocal, and there is no defocus within the temperature range of -40°C to 80°C.

[0083] Embodiment 3:

[0084] Figure 11 Schematically show the lens structure diagram according to Embodiment 3 of the present invention.

[0085] In this embodiment, the total lens length TTL = 22.2 mm, FN0 = 1.0, the aperture stop S is located on the image side of the third lens 3. The third lens 3, the fourth lens 4 and the fifth lens are glass lenses, the sixth lens 6 is a plastic lens, and the third lens 3 and the fifth lens 5 are low-dispersion glass lenses. The refractive indices Nd of the third lens 3 and the seventh lens 7 are ≥1.6.

[0086] The following Table 6 lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0087] Surface Serial Number Surface Type R Value Thickness Refractive Index Abbe Number S1 Aspherical Surface 200.498 0.6 1.53 56.1 S2 Aspherical Surface 3.75 2.04 S3 Aspherical Surface -19.001 0.6 1.52 54.2 S4 Aspherical Surface 21.11 1.22 S5 Spherical Surface -7.194 3.19 1.62 63.4 S6(STO) Spherical Surface -6.181 0.6 S7 Spherical Surface 8.7 3.5 1.92 24.0 S8 Spherical Surface 6.451 1.73 1.46 90.62 S9 Spherical Surface -16.719 0.1 S10 Aspherical Surface 5.629 2.02 1.53 56.1 S11 Aspherical Surface -75.174 0.16 S12 Aspherical Surface -9.03 0.6 1.63 23.5 S13 Aspherical Surface 7.374 0.23 S14 Aspherical Surface 3.583 1.61 1.53 56.1 S15 Aspherical Surface -20.349 3 S16 Spherical Surface Infinity 0.8 1.52 64.2 S17 Spherical Surface Infinity 0.2 S18(IMA) Spherical Surface Infinity

[0088] Table 6

[0089] Table 7 lists the aspheric coefficients of each aspheric lens in this embodiment. K is the conic constant of the surface, and A, B, C, D, E, and F are the aspheric coefficients of the fourth, sixth, eighth, tenth, twelfth, and fourteenth orders, respectively.

[0090]

[0091]

[0092] Table 7

[0093] Figures 12 - 15 Schematically show the MTF diagram of the lens of Embodiment 3, the Through-Focus-MTF diagram with a frequency of 120 lp / mm, the Through-Focus-MTF diagram with an outer frequency of 120 lp / mm, and the ray fan diagram. It can be seen from the accompanying drawings that for the lens obtained according to Embodiment 3 of the present invention, the aperture number can reach F1.0, and at the same time, the infrared defocus amount of the lens is within 0.006 mm, enabling day and night confocal, and at the same time, there is no defocus within the temperature range of -40°C to 80°C.

[0094] Embodiment 4:

[0095] Figure 16 Schematically shows the lens structure diagram according to Embodiment 4 of the present invention.

[0096] In this embodiment, the total lens length TTL = 22.2 mm, FN0 = 1.0, the diaphragm S is located on the object side surface of the fourth lens 4, the third lens 3 is a plastic lens, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are glass lenses, and the fifth lens 5 and the sixth lens 6 are low-dispersion glass lenses. The refractive indices Nd of the third lens 3 and the seventh lens 7 are ≥1.6.

[0097] The following Table 8 lists the relevant parameters of each lens in this embodiment, including the surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0098] Surface Serial Number Surface Type R Value Thickness Refractive Index Abbe Number S1 Aspherical Surface 195.973 0.6 1.50 56.1 S2 Aspherical Surface 3.527 3.28 S3 Aspherical Surface -14.335 0.51 1.50 56.1 S4 Aspherical Surface 5.901 0.33 S5 Aspherical Surface 7.624 2.5 1.63 20.9 S6 Aspherical Surface -23.425 0.61 S7(STO) Spherical Surface -11.618 0.48 1.69 31.2 S8 Spherical Surface 4.622 2.43 1.59 67.0 S9 Spherical Surface -10.01 0.09 S10 Spherical Surface 7.143 2.39 1.46 90.2 S11 Spherical Surface -9.971 0.1 S12 Aspherical Surface 7.784 0.5 1.60 25.5 S13 Aspherical Surface 3.601 0.19 S14 Aspherical Surface 3.822 2.82 1.53 56.1 S15 Aspherical Surface -16.339 4.37 S16 Spherical Surface Infinity 0.8 1.52 64.2 S17 Spherical Surface Infinity 0.2 S18(IMA) Spherical Surface Infinity

[0099] Table 8

[0100] Table 9 lists the aspheric coefficients of each aspheric lens in this embodiment. K is the conic constant of the surface, and A, B, C, D, E, and F are the aspheric coefficients of the fourth, sixth, eighth, tenth, twelfth, and fourteenth orders, respectively.

[0101] Surface Serial Number K A B C D E S1 0.0000E+00 2.3692E-04 3.0607E-06 -5.1584E-10 -1.1245E-11 -5.2709E-11 S2 0.0000E+00 -1.3408E-04 -8.3404E-05 2.9147E-06 1.6576E-06 4.5722E-08 S3 -1.5298E+01 -1.0483E-03 -6.0721E-05 -2.0514E-06 -5.1194E-07 -2.5634E-09 S4 -6.7423E-01 -1.4519E-04 -5.9789E-06 2.0581E-06 -9.8037E-08 1.9601E-09 S5 0.0000E+00 -1.2355E-03 9.9494E-06 2.6502E-07 3.2726E-07 5.9228E-08 S6 -3.2148E-01 -4.1490E-03 -8.7129E-06 -3.0100E-07 2.3035E-07 -7.0648E-08 S12 3.6513E-01 -3.4459E-03 -6.7679E-06 1.2560E-07 9.2484E-08 2.1808E-09 S13 -8.5142E+00 -1.1599E-03 -2.1059E-05 2.7324E-08 9.1696E-08 1.1902E-10 S14 -6.7289E+00 -2.8463E-03 3.7495E-04 -4.9025E-07 -2.3276E-08 -5.1353E-10 S15 5.0000E+01 -8.7957E-04 -2.9256E-04 -8.9082E-07 1.1272E-08 -8.7955E-10

[0102] Table 9

[0103] Figures 17 - 20 Schematically show the MTF graph of the lens of Embodiment 4, the Through-Focus-MTF graph with a frequency of 120 lp / mm, the Through-Focus-MTF graph with an outer frequency of 120 lp / mm, and the ray fan graph. It can be known from the accompanying drawings that for the lens obtained according to Embodiment 4 of the present invention, the aperture number can reach F1.0, and at the same time, the infrared defocus amount of the lens is within 0.006 mm, enabling day and night confocal, and at the same time, there is no defocus within the temperature range of -40°C to 80°C.

[0104] Embodiment Five:

[0105] Figure 21 Schematically shows the lens structure diagram according to Embodiment 5 of the present invention.

[0106] In this embodiment, the total length of the lens TTL = 22.2 mm, FN0 = 1.0, the aperture stop S is located between the third lens 3 and the fourth lens 4. The third lens 3 is a plastic lens, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are glass lenses, and the fifth lens 5 and the sixth lens 6 are low-dispersion glass lenses. The refractive indices Nd of the third lens 3 and the seventh lens 7 are ≥ 1.6.

[0107] The following Table 10 lists the relevant parameters of each lens in this embodiment, including the surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0108]

[0109]

[0110] Table 10

[0111] Table 11 lists the aspheric coefficients of each aspheric lens in this embodiment. K is the conic constant of the surface, and A, B, C, D, E, and F are the aspheric coefficients of the fourth, sixth, eighth, tenth, twelfth, and fourteenth orders, respectively.

[0112] Surface Serial Number K A B C D E S1 -2.5851E+01 -7.9013E-04 4.5134E-05 -1.2980E-06 1.8830E-08 9.4149E-10 S2 -3.8443E-01 -2.9300E-03 -9.4775E-05 1.9493E-05 -2.0219E-06 -1.0109E-07 S3 -2.0288E+00 -9.6133E-04 2.2139E-05 0.0000E+00 0.0000E+00 0.0000E+00 S4 -1.1032E+00 4.1411E-03 -1.0009E-04 1.2900E-05 -1.7653E-07 -8.8266E-09 S5 3.0658E+01 -1.0082E-03 5.6836E-05 -9.4815E-07 -1.2732E-07 -6.3658E-09 S6 7.5393E+00 -2.8145E-04 3.5594E-05 -6.8417E-07 -9.0029E-08 -4.5014E-09 S13 2.4306E+00 -2.1930E-03 1.2970E-04 -8.0836E-06 1.5715E-07 7.8575E-09 S14 -2.7363E-01 -2.2812E-03 4.0937E-05 -4.7335E-06 -1.3582E-07 -6.7909E-09 S15 -5.8977E-01 3.2580E-04 -8.8243E-05 1.9353E-06 -1.4068E-07 -7.0338E-09 S16 -1.2603E+01 1.0384E-03 -4.7128E-05 -8.7143E-07 1.1979E-07 5.9897E-09

[0113] Table 11

[0114] Figures 22 - 25Schematically show the MTF diagram of the lens of Embodiment 5, the Through-Focus-MTF diagram with a frequency of 120 lp / mm, the Through-Focus-MTF diagram with an outer frequency of 120 lp / mm, and the ray fan diagram respectively. It can be known from the accompanying drawings that for the lens obtained according to Embodiment 5 of the present invention, the aperture number can reach F1.0, and at the same time, the infrared defocus amount of the lens is within 0.006 mm, enabling day and night confocal, and at the same time, there is no defocus within the temperature range of -40°C to 80°C.

[0115] The above description is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lens, along the optical axis from the object side to the image side direction, successively includes a first lens (1) with negative optical power, a second lens (2) with negative optical power, a third lens (3) with positive optical power, a fourth lens (4) with negative optical power, a fifth lens (5) with positive optical power, a sixth lens (6) with positive optical power, a seventh lens (7) with negative optical power, and an eighth lens (8) with positive optical power; It is characterized in that The first lens (1), the second lens (2), the seventh lens (7), and the eighth lens (8) are plastic lenses, and at least three of the third lens (3), the fourth lens (4), the fifth lens (5), and the sixth lens (6) are glass lenses; The effective focal length from the first lens (1) to the third lens (3) is f1, and the effective focal length of the lens is f, satisfying the relation: -2.39 ≤ f1 / f ≤ -1; The effective focal length from the fourth lens (4) to the eighth lens (8) is f2, and the effective focal length of the lens is f, satisfying the relation: 1.6 ≤ f2 / f ≤ 1.

93.

2. The lens according to claim 1, characterized in that, The lens further includes a diaphragm (S), and the diaphragm (S) is located on the image side surface of the third lens (3), or between the third lens (3) and the fourth lens (4), or on the object side surface of the fourth lens (4).

3. The lens according to claim 2, characterized in that, The fourth lens (4) and the fifth lens (5) form a cemented lens group with positive optical power.

4. The lens according to claim 1, characterized in that, Along the object side to the image side direction, the first lens (1) is a convex-concave lens, the second lens (2) is a concave-concave lens or a concave-convex lens, the third lens (3) is a convex-convex lens or a concave-convex lens, the fourth lens (4) is a concave-concave lens or a convex-concave lens, the seventh lens (7) is a concave-concave lens or a convex-concave lens, and the fifth lens (5), the sixth lens (6), and the eighth lens (8) are all convex-convex lenses.

5. The lens according to any one of claims 1-4, characterized in that, At least one of the third lens (3), the fourth lens (4), the fifth lens (5), and the sixth lens (6) is a low-dispersion glass lens with an Abbe number Vd ≥ 60.

6. The lens according to any one of claims 1-4, characterized in that, At least two of the first lens (1), the second lens (2), the third lens (3), the seventh lens (7), and the eighth lens (8) have a refractive index Nd ≥ 1.

6.

7. The lens according to any one of claims 1-4, characterized in that, The distance from the center of the image side surface of the eighth lens (8) to the image plane of the lens is d, and the distance from the object side surface of the first lens (1) to the image plane of the lens is D, satisfying the relation: d / D ≥ 0.

18.

8. The lens according to any one of claims 1 to 4, characterized in that, The Abbe numbers of the fourth lens (4) and the fifth lens (5) are v4 and v5 respectively, satisfying the relation: |v4 - v5| ≥ 30.

9. The lens according to any one of claims 1-4, characterized in that, The relative aperture of the lens FNO ≤ 1.2.

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