An imaging lens

Abstract

The present invention relates to an imaging lens, which sequentially includes a first lens group (1) with positive optical power, a diaphragm (2), and a second lens group (3) along the optical axis from the object side to the image side; the first lens group (1) is a fixed lens group, and the second lens group (3) is a focusing lens group that can reciprocally move along the optical axis direction; the first lens group (1) includes at least seven lenses, and the second lens group (3) includes four lenses. The lens of the present invention has more delicate imaging, a higher dynamic imaging range, a larger depth of field, good color and contrast, a wider application range, and at the same time, due to the smaller distortion characteristics of the lens itself, the lens has a wider field of view.

Description

Technical Field

[0001] The present invention relates to the field of optics, and particularly to an imaging lens. Background Art

[0002] Machine vision is a comprehensive technology, including image processing, mechanical engineering technology, control, electric light source illumination, optical imaging, sensors, analog and digital video technology, computer software and hardware technology (image enhancement and analysis algorithms, image cards, I / O cards, etc.). A typical machine vision application system includes image capture, light source system, image digitization module, digital image processing module, intelligent judgment and decision-making module, and mechanical control execution module.

[0003] With the development of the imaging lens industry, various imaging lenses have emerged. However, these imaging lenses have poor optical resolution and large imaging distortion. Although such imaging lenses have a wide shooting range, their imaging is not delicate enough, the dynamic range during imaging is not high, the color and contrast are not good enough, and at the same time, the transmittance deviation is relatively large. The application fields of such lenses are limited. Especially in the field of machine vision, their imaging performance is difficult to meet the corresponding technical requirements. Summary of the Invention

[0004] The purpose of the present invention is to provide an imaging lens to solve the problem of poor performance of imaging lenses.

[0005] To achieve the above purpose, the present invention provides an imaging lens, which sequentially includes a first lens group with positive optical power, a diaphragm, and a second lens group along the optical axis from the object side to the image side direction;

[0006] The first lens group is a fixed lens group, and the second lens group is a focusing lens group that can reciprocally move along the optical axis direction;

[0007] The first lens group includes at least seven lenses, and the second lens group includes four lenses.

[0008] According to one aspect of the present invention, among the lenses included in the first lens group, at least four lenses have negative optical power, and at least three lenses have positive optical power.

[0009] According to one aspect of the present invention, among the lenses included in the second lens group, one lens has negative optical power, and the remaining lenses have positive optical power.

[0010] According to one aspect of the present invention, the first lens group includes seven lenses or eight lenses.

[0011] According to one aspect of the present invention, along the optical axis from the object side to the image side direction, the first lens in the first lens group is a convex-concave lens with positive optical power, and its object side surface is a convex surface.

[0012] According to one aspect of the present invention, the lens with negative optical power in the first lens group is a meniscus lens.

[0013] According to one aspect of the present invention, along the optical axis from the object side to the image side, the object side surface of the second lens in the first lens group is a convex surface.

[0014] According to one aspect of the present invention, the first lens group has a cemented lens formed by cementing multiple lenses.

[0015] According to one aspect of the present invention, among the lenses with negative optical power in the first lens group, three lenses are meniscus lenses and one lens is a biconcave lens.

[0016] According to one aspect of the present invention, among the lenses included in the second lens group, there are three biconvex lenses and one biconcave lens.

[0017] According to one aspect of the present invention, the second lens group has a cemented lens formed by cementing multiple lenses.

[0018] According to one aspect of the present invention, if the focal length of the first lens group is F1 and the focal length of the imaging lens is F, then the following is satisfied: 1.0 ≤ F1 / F ≤ 14.4.

[0019] According to one aspect of the present invention, if the focal length of the second lens group is F2 and the focal length of the imaging lens is F, then the following is satisfied: -48.6 ≤ F2 / F ≤ 4.4.

[0020] According to one aspect of the present invention, if the total optical system length of the imaging lens is L and the focal length of the imaging lens is F, then the following is satisfied: 3.3 ≤ L / F ≤ 18.7.

[0021] According to one aspect of the present invention, if the refractive index of one lens in the cemented lens of the second lens group is ND and the Abbe number is VD, then the following is satisfied: 1.43 ≤ ND ≤ 1.60, 66 ≤ VD ≤ 95.

[0022] According to one solution of the present invention, the imaging of the lens of the present invention is more delicate, the dynamic imaging range is higher, the depth of field is larger, the color and contrast are also good, its application range is wider, and at the same time, due to the relatively small distortion characteristic of the lens itself, the field of view of the lens is wider.

[0023] According to one embodiment of the present invention, the imaging lens of the present invention adopts a structure of two lens groups. Among them, the first lens group serves as a fixed group, which functions to bend the optical path and expand the aperture, enabling light to smoothly enter the imaging system while ensuring the aperture size, thereby reducing the tolerance sensitivity of the system. Additionally, in the way of matching multiple positive and negative lenses, the structure of the imaging lens of the present invention facilitates correcting the imaging performance of the system in high and low temperature environments, achieving excellent imaging performance of the imaging lens in different environments.

[0024] According to one embodiment of the present invention, the second lens group serves as a focusing lens group, which enables the imaging lens of the present invention to clearly image at different object distances, corrects the monochromatic aberration of the imaging lens, ensures the consistency of image quality under low distortion conditions, and simultaneously corrects chromatic aberration to ensure good color reproducibility.

[0025] According to one embodiment of the present invention, in the first lens group, by using a combination of lenses with multiple positive and negative optical powers, it is convenient to correct the imaging performance of the system in high and low temperature environments. At the same time, using multiple convex and concave lenses facilitates correcting the monochromatic aberration and distortion of the system, reduces the tolerance sensitivity of the imaging lens, and improves the image clarity.

[0026] According to one embodiment of the present invention, the second lens group is formed by combining the positive and negative optical powers of lenses and gluing multiple lenses to form a cemented lens, which is beneficial to correcting the monochromatic aberration and chromatic aberration of the entire second lens group, can effectively reduce the tolerance sensitivity of the optical system, and improve the imaging quality of the optical lens.

[0027] According to one embodiment of the present invention, the positive and negative optical powers and the magnitudes of the optical powers of the first lens group and the entire imaging lens are reasonably matched, which can better ensure the low distortion performance of the imaging lens and effectively ensure the reduction of the tolerance sensitivity of the imaging lens.

[0028] According to one embodiment of the present invention, the positive and negative optical powers and the magnitudes of the optical powers of the second lens group and the entire imaging lens are reasonably matched, which can better avoid the deterioration of the focusing performance at different object distances and is beneficial to reducing the tolerance sensitivity of the imaging lens.

[0029] According to one embodiment of the present invention, the effect of reasonably controlling the total length of the system is achieved, and the volume of the entire imaging lens can also be balanced to control costs, ensuring the imaging quality of the imaging lens and resulting in a high image quality contrast.

[0030] According to one embodiment of the present invention, one of the lenses forming the cemented lens in the second lens group uses a low-dispersion material, which is beneficial to correcting the overall chromatic aberration of the imaging lens, can also avoid the deterioration of the focusing performance at different object distances, and is easy to correct the high and low temperature performance of the imaging lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram showing the structure of an imaging lens according to Embodiment 1 of the present invention;

[0032] Figure 2 Schematic diagram showing the lens resolution of an imaging lens according to Embodiment 1 of the present invention;

[0033] Figure 3 Schematic diagram showing the lens distortion of an imaging lens according to Embodiment 1 of the present invention;

[0034] Figure 4 Schematic diagram showing the high-temperature defocus curve of an imaging lens according to Embodiment 1 of the present invention;

[0035] Figure 5 Schematic diagram showing the low-temperature defocus curve of an imaging lens according to Embodiment 1 of the present invention;

[0036] Figure 6 Schematic diagram showing the structure of an imaging lens according to Embodiment 2 of the present invention;

[0037] Figure 7 Schematic diagram showing the lens resolution of an imaging lens according to Embodiment 2 of the present invention;

[0038] Figure 8 Schematic diagram showing the lens distortion of an imaging lens according to Embodiment 2 of the present invention;

[0039] Figure 9 Schematic diagram showing the high-temperature defocus curve of an imaging lens according to Embodiment 2 of the present invention;

[0040] Figure 10 Schematic diagram showing the low-temperature defocus curve of an imaging lens according to Embodiment 2 of the present invention;

[0041] Figure 11 Schematic diagram showing the structure of an imaging lens according to Embodiment 3 of the present invention;

[0042] Figure 12 Schematic diagram showing the lens resolution of an imaging lens according to Embodiment 3 of the present invention;

[0043] Figure 13 Schematic diagram showing the lens distortion of an imaging lens according to Embodiment 3 of the present invention;

[0044] Figure 14 Schematic diagram showing the high-temperature defocus curve of an imaging lens according to Embodiment 3 of the present invention;

[0045] Figure 15 Schematic diagram showing the low-temperature defocus curve of an imaging lens according to Embodiment 3 of the present invention;

[0046] Figure 16 Schematic structural diagram of an imaging lens according to Embodiment 4 of the present invention;

[0047] Figure 17 Schematic resolution force diagram of an imaging lens according to Embodiment 4 of the present invention;

[0048] Figure 18 Schematic distortion diagram of an imaging lens according to Embodiment 4 of the present invention;

[0049] Figure 19 Schematic high-temperature defocus curve diagram of an imaging lens according to Embodiment 4 of the present invention;

[0050] Figure 20 Schematic low-temperature defocus curve diagram of an imaging lens according to Embodiment 4 of the present invention;

[0051] Figure 21 Schematic structural diagram of an imaging lens according to Embodiment 5 of the present invention;

[0052] Figure 22 Schematic resolution force diagram of an imaging lens according to Embodiment 5 of the present invention;

[0053] Figure 23 Schematic distortion diagram of an imaging lens according to Embodiment 5 of the present invention;

[0054] Figure 24 Schematic high-temperature defocus curve diagram of an imaging lens according to Embodiment 5 of the present invention;

[0055] Figure 25 Schematic low-temperature defocus curve diagram of an imaging lens according to Embodiment 5 of the present invention. Detailed implementation manners

[0056] 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 drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0057] The present invention will be described in detail below in conjunction with the 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.

[0058] As Figure 1As shown, according to an embodiment of the present invention, in the imaging lens of the present invention, along the optical axis from the object side to the image side, it sequentially includes a first lens group 1 with positive optical power, a diaphragm 2, and a second lens group 3. In this embodiment, the first lens group 1 is a fixed lens group, and the second lens group 3 is a focusing lens group that can reciprocally move along the optical axis direction; the first lens group 1 includes at least seven lenses, and the second lens group 3 includes four lenses. In this embodiment, when imaging from infinity to a short distance, the second lens group 3 moves along the optical axis direction for focusing.

[0059] As Figure 1 shown, according to an embodiment of the present invention, among the lenses included in the first lens group 1, at least four lenses have negative optical power, and at least three lenses have positive optical power.

[0060] As Figure 1 shown, according to an embodiment of the present invention, among the lenses included in the second lens group 3, one lens has negative optical power, and the remaining lenses have positive optical power.

[0061] According to an embodiment of the present invention, the first lens group 1 includes seven lenses or eight lenses.

[0062] Through the above settings, the imaging lens of the present invention adopts a two-group structure, where the first lens group 1 serves as a fixed group, playing the role of turning the optical path and expanding the aperture, enabling light to smoothly enter the imaging system while ensuring the aperture size, thereby reducing the tolerance sensitivity of the system. Additionally, in the way of matching multiple positive and negative lenses, the structure of the imaging lens of the present invention facilitates correcting the imaging performance of the system in high and low temperature environments, achieving excellent imaging performance of the imaging lens in different environments.

[0063] Furthermore, the second lens group 3 serves as a focusing lens group, enabling the imaging lens of the present invention to clearly image at different object distances, correcting the monochromatic aberration of the imaging lens, ensuring the consistency of image quality under low distortion conditions, and simultaneously correcting chromatic aberration to ensure good color reproducibility.

[0064] As Figure 1 shown, according to an embodiment of the present invention, along the optical axis from the object side to the image side, the first lens L1 in the first lens group 1 is a convex-concave lens with positive optical power, and the object side surface of the first lens group 1 is a convex surface. That is, the first lens group 1 of the present invention has a convex-concave lens with positive optical power, which is arranged at the position closest to the object side of the imaging lens, and the surface close to the object side is a convex surface.

[0065] As Figure 1 shown, according to an embodiment of the present invention, one lens with negative optical power in the first lens group 1 is a convex-concave lens.

[0066] AsFigure 1 As shown, according to an embodiment of the present invention, along the optical axis from the object side to the image side direction, the object side surface of the second lens L2 in the first lens group 1 is a convex surface.

[0067] As Figure 1 shown, according to an embodiment of the present invention, the first lens group 1 has a cemented lens formed by cementing multiple lenses.

[0068] As Figure 1 shown, according to an embodiment of the present invention, among the lenses with negative optical power in the first lens group 1, three lenses are meniscus lenses and one lens is a biconcave lens.

[0069] Through the above settings, in the first lens group 1, by using lenses with multiple positive and negative optical powers in combination, it is convenient to correct the imaging performance of the system in high and low temperature environments. At the same time, using multiple convex and concave lenses is convenient for correcting the monochromatic aberration and distortion of the system, reducing the tolerance sensitivity of the imaging lens, and improving the picture clarity.

[0070] As Figure 1 shown, according to an embodiment of the present invention, among the lenses included in the second lens group 3, there are three biconvex lenses and one biconcave lens.

[0071] As Figure 1 shown, according to an embodiment of the present invention, the second lens group 3 has a cemented lens formed by cementing multiple lenses.

[0072] Through the above settings, in the second lens group 3, by combining the positive and negative optical powers of the lenses and forming a cemented lens by cementing multiple lenses, it is beneficial to correct the monochromatic aberration and chromatic aberration of the entire second lens group 3, can effectively reduce the tolerance sensitivity of the optical system, and improve the imaging quality of the optical lens.

[0073] As Figure 1 shown, according to an embodiment of the present invention, if the focal length of the first lens group 1 is F1 and the focal length of the imaging lens is F, then it satisfies: 1.0 ≤ F1 / F ≤ 14.4.

[0074] Through the above settings, a reasonable combination of the positive and negative optical powers and the magnitudes of the optical powers of the first lens group 1 and the entire imaging lens is achieved, which can better ensure the low distortion performance of the imaging lens and effectively ensure the reduction of the tolerance sensitivity of the imaging lens.

[0075] As Figure 1 shown, according to an embodiment of the present invention, if the focal length of the second lens group 3 is F2 and the focal length of the imaging lens is F, then it satisfies: -48.6 ≤ F2 / F ≤ 4.4.

[0076] Through the above settings, the positive and negative optical powers and the magnitudes of the optical powers of the second lens group 3 and the entire imaging lens are reasonably matched, which can better avoid the deterioration of the focusing performance at different object distances and is beneficial to reducing the tolerance sensitivity of the imaging lens.

[0077] As Figure 1 shown, according to an embodiment of the present invention, the total optical length of the optical system of the imaging lens is L, and the focal length of the imaging lens is F, then it satisfies: 3.3 ≤ L / F ≤ 18.7.

[0078] Through the above settings, the effect of reasonably controlling the total optical length of the system is achieved, and the volume of the entire imaging lens can be balanced to control costs, ensuring the imaging quality of the imaging lens and making the image quality contrast high.

[0079] As Figure 1 shown, according to an embodiment of the present invention, the refractive index of one lens in the cemented lens of the second lens group 3 is ND, and the Abbe number is VD, then it satisfies: 1.43 ≤ ND ≤ 1.60, 66 ≤ VD ≤ 95.

[0080] Through the above settings, one of the lenses constituting the cemented lens in the second lens group 3 uses a low-dispersion material, which is beneficial to correcting the overall chromatic aberration of the imaging lens. At the same time, it can also avoid the deterioration of the focusing performance at different object distances and is easy to correct the high and low temperature performance of the imaging lens.

[0081] The following gives 5 specific embodiments according to the above settings of the present invention to specifically illustrate the imaging lens according to the present invention

[0082] The data of the five groups of embodiments are as follows in Table 1:

[0083] Conditional Example 1 Example 2 Example 3 Example 4 Example 5 1.0 ≤ F1 / F ≤ 14.4 2.9 1.0 2.2 14.4 7.5 -48.6 ≤ F2 / F ≤ 4.4 1.8 0.8 -48.6 3.8 4.4 3.3 ≤ L / F ≤ 18.7 9.6 3.3 7.0 18.7 6.6 1.43 ≤ ND ≤ 1.60 1.43 1.50 1.50 1.49 1.60 66 ≤ VD ≤ 95 95 81 81 70 66

[0084] Table 1

[0085] Embodiment 1:

[0086] As Figure 1As shown in the figure, the imaging lens of the present invention comprises a total of 11 lenses. Among them, the first lens group 1 has 7 lenses (i.e., the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7), and the second lens group 3 has 4 lenses (i.e., the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11). In this embodiment, there is a cemented lens formed by gluing two lenses in the first lens group 1, and a cemented lens formed by gluing three lenses in the second lens group. A filter A and an image plane are further provided on the image side of the second lens group. Furthermore, the imaging system constituted by this imaging lens comprises a total of 23 optical surfaces. For the convenience of description, they are sequentially numbered as S1 - S23, where S14 is replaced by the aperture stop STO, and S23 is represented by Φi.

[0087] In this embodiment, the parameters of the imaging lens of the present invention are as follows:

[0088] Focal length f = 6.8 mm;

[0089] Aperture value FNO = 2.0.

[0090] The following Table 2 lists the relevant parameters of each lens in this embodiment, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0091]

[0092]

[0093] Table 2

[0094] Combined with the attached Figures 2 - 5 It can be known that according to the imaging lens of this embodiment, adopting the structure of the front and rear lens groups and 11 lenses, an aperture of F2.0 can be achieved, and the effects of correcting monochromatic aberration and chromatic aberration on the image side can be achieved; at the same time, in the high and low temperature environment of -40°C to +80°C, high-resolution imaging can be satisfied without refocusing. In addition, the advantages of small lens size, large aperture, low tolerance sensitivity, high image quality contrast, etc. are also achieved, and it is applicable to more different conditions of scenarios.

[0095] Embodiment 2:

[0096] As Figure 6As shown in the figure, the imaging lens of the present invention comprises a total of 11 lenses. Among them, the first lens group 1 has 7 lenses (i.e., the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7), and the second lens group 3 has 4 lenses (i.e., the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11). In this embodiment, there is a cemented lens formed by gluing three lenses in the first lens group 1, and there is a cemented lens formed by gluing three lenses in the second lens group 3. A filter A and an image plane are further provided on the image side of the second lens group. Furthermore, the imaging system constituted by this imaging lens comprises a total of 22 optical surfaces. For the convenience of description, they are sequentially numbered as S1 - S22, where S13 is replaced by the aperture stop STO, and S22 is represented by Φi.

[0097] In this embodiment, the parameters of the imaging lens of the present invention are as follows:

[0098] The focal length f = 15.3 mm;

[0099] The aperture value FNO = 2.4.

[0100] The following Table 3 lists the relevant parameters of each lens in this embodiment, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0101]

[0102]

[0103] Table 3

[0104] Combined with the attached Figures 7 - 10 It can be known that according to the imaging lens of this embodiment, adopting the structure of the front and rear lens groups and 11 lenses, an aperture of F2.4 can be achieved, and the effects of correcting monochromatic aberration and chromatic aberration can be achieved; at the same time, in the high and low temperature environment of -40°C to +80°C, high-resolution imaging can be satisfied without refocusing. In addition, the advantages of small lens size, large aperture, low tolerance sensitivity, high image quality contrast, etc. are achieved, and it is suitable for more different condition scenarios.

[0105] Embodiment 3:

[0106] As Figure 11As shown in the figure, the imaging lens of the present invention comprises a total of 12 lenses. Among them, the first lens group 1 has 8 lenses (i.e., the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8), and the second lens group 3 has 4 lenses (i.e., the ninth lens L9, the tenth lens L10, the eleventh lens L11, and the twelfth lens L12). In this embodiment, there is a cemented lens formed by gluing two lenses in the first lens group 1, and there is a cemented lens formed by gluing three lenses in the second lens group 3. A filter A and an image plane are also provided on the image side of the second lens group. Furthermore, the imaging system composed of this imaging lens has a total of 25 optical surfaces. For the convenience of description, they are sequentially numbered as S1 - S25, where S16 is the aperture stop replaced by STO, and S25 is represented by Φi.

[0107] In this embodiment, the parameters of the imaging lens of the present invention are as follows:

[0108] The focal length f = 7.4 mm;

[0109] The aperture value FNO = 2.3.

[0110] The following Table 4 lists the relevant parameters of each lens in this embodiment, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0111]

[0112]

[0113] Table 4

[0114] Combined with the attached Figures 12 - 15 It can be known that according to the imaging lens of this embodiment, adopting the structure of the front and rear lens groups and 11 lenses, an aperture of F2.3 can be achieved, and the effects of correcting monochromatic lateral and chromatic aberrations can be achieved; at the same time, in the high and low temperature environment of -40°C to +80°C, high-resolution imaging can be satisfied without refocusing. In addition, it also has the advantages of small lens size, large aperture, low tolerance sensitivity, high image quality contrast, etc., and is suitable for more different condition scenarios.

[0115] Embodiment 4:

[0116] As Figure 16As shown in the figure, the imaging lens of the present invention comprises a total of 12 lenses. Among them, the first lens group 1 has 8 lenses (i.e., the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8), and the second lens group 3 has 4 lenses (i.e., the ninth lens L9, the tenth lens L10, the eleventh lens L11, and the twelfth lens L12). In this embodiment, there is a cemented lens formed by gluing two lenses in the first lens group 1, and there is a cemented lens formed by gluing two lenses in the second lens group 3. A filter A and an image plane are also provided on the image side of the second lens group. Furthermore, the imaging system constituted by this imaging lens comprises a total of 26 optical surfaces. For the convenience of description, they are sequentially numbered as S1 - S26, where S16 is the aperture stop replaced by STO, and S26 is represented by Φi.

[0117] In this embodiment, the parameters of the imaging lens of the present invention are as follows:

[0118] Focal length f = 4.8 mm;

[0119] Aperture value FNO = 2.2.

[0120] The following Table 5 lists the relevant parameters of each lens in this embodiment, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0121]

[0122]

[0123] Table 5

[0124] Combined with the attached Figures 17 - 20 It can be known that according to the imaging lens of this embodiment, adopting the structure of front and rear lens groups and 11 lenses, an aperture of F2.2 can be achieved, and the effects of correcting monochromatic lateral aberration and chromatic aberration can be achieved; at the same time, in the high and low temperature environment of -40°C to +80°C, high-resolution imaging can be satisfied without refocusing. In addition, the advantages of small lens size, large aperture, low tolerance sensitivity, high image quality contrast, etc. are achieved, and it is suitable for more different conditions of scenarios.

[0125] Embodiment Five:

[0126] As Figure 21As shown in the figure, the imaging lens of the present invention comprises a total of 11 lenses. Among them, the first lens group 1 has 7 lenses (i.e., the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7), and the second lens group 3 has 4 lenses (i.e., the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11). In this embodiment, there is a cemented lens formed by gluing two lenses in the first lens group 1, and there is a cemented lens formed by gluing two lenses in the second lens group 3. A filter A and an image plane are also provided on the image side of the second lens group. Furthermore, the imaging system constituted by this imaging lens comprises a total of 24 optical surfaces. For the convenience of description, they are sequentially numbered as S1 - S24, where S14 is the aperture stop replaced by STO, and S24 is represented by Φi.

[0127] In this embodiment, the parameters of the imaging lens of the present invention are as follows:

[0128] Focal length f = 8.1 mm;

[0129] Aperture value FNO = 2.0.

[0130] The following Table 6 lists the relevant parameters of each lens in this embodiment, including the radius of curvature, thickness, refractive index of the material, and Abbe number:

[0131]

[0132]

[0133] Table 6

[0134] Combined with the attached Figures 22 - 25 It can be known that according to the imaging lens of this embodiment, adopting the structure of front and rear lens groups and 11 lenses, an aperture of F2.0 can be achieved, and the effects of correcting monochromatic aberration on the image side and chromatic aberration can be achieved; at the same time, in the high and low temperature environment of -40°C to +80°C, high-resolution imaging can be satisfied without refocusing. In addition, the advantages of small lens size, large aperture, low tolerance sensitivity, high image quality contrast, etc. are also achieved, and it is suitable for more different condition scenarios.

[0135] 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. An imaging lens, characterized in that along the optical axis from the object side to the image side, it sequentially includes a first lens group (1) with positive optical power, a diaphragm (2), and a second lens group (3), totaling two lens groups; the first lens group (1) is a fixed lens group, and the second lens group (3) is a focusing lens group that can reciprocally move along the optical axis direction; the first lens group (1) only contains seven lenses. Along the optical axis from the object side to the image side, the optical powers of the first lens group (1) are positive, negative, negative, positive, negative, positive, and negative respectively; or the first lens group (1) only contains eight lenses. Along the optical axis from the object side to the image side, the optical powers of the first lens group (1) are positive, negative, negative, negative, positive, negative, positive, and negative respectively; the second lens group (3) only contains four lenses. Along the optical axis from the object side to the image side, the optical powers of the lenses in the second lens group (3) are positive, negative, positive, and positive respectively.

2. The imaging lens according to claim 1, characterized in that along the optical axis from the object side to the image side, the first lens (L1) in the first lens group (1) is a convex-concave lens with positive optical power.

3. The imaging lens according to claim 2, characterized in that when the first lens group (1) only contains seven lenses, the second lens and the seventh lens in the first lens group (1) along the optical axis from the object side to the image side are convex-concave lenses; or, when the first lens group (1) only contains eight lenses, the second lens, the third lens, and the eighth lens in the first lens group (1) along the optical axis from the object side to the image side are convex-concave lenses.

4. The imaging lens according to claim 3, characterized in that two lenses in the first lens group (1) are cemented to form a doublet lens, or three lenses in the first lens group (1) are cemented to form a triplet lens.

5. The imaging lens according to claim 4, characterized in that when the first lens group (1) only contains seven lenses, the third lens in the first lens group (1) along the optical axis from the object side to the image side is a biconcave lens, the fifth lens is a convex-concave lens, and the sixth lens is a biconvex lens; or, when the first lens group (1) only contains eight lenses, the fourth lens in the first lens group (1) along the optical axis from the object side to the image side is a biconcave lens, the sixth lens is a convex-concave lens, and the seventh lens is a biconvex lens.

6. The imaging lens according to claim 1, characterized in that among the lenses included in the second lens group (3), along the optical axis from the object side to the image side, the second lens is a biconcave lens, and the other three lenses are biconvex lenses.

7. The imaging lens according to claim 6, characterized in that two lenses in the second lens group (3) are cemented to form a doublet lens, or three lenses in the second lens group (3) are cemented to form a triplet lens.

8. The imaging lens according to claim 1, characterized in that If the focal length of the first lens group (1) is F1 and the focal length of the imaging lens is F, then the following condition is satisfied: 1.0 ≤ F1 / F ≤ 14.

4.

9. The imaging lens according to claim 1, wherein, if the focal length of the second lens group (3) is F2 and the focal length of the imaging lens is F, then the following condition is satisfied: -48.6 ≤ F2 / F ≤ 4.

4.

10. The imaging lens according to claim 1, wherein, if the total optical length of the imaging lens is L and the focal length of the imaging lens is F, then the following condition is satisfied: 3.3 ≤ L / F ≤ 18.

7.

11. The imaging lens according to claim 7, wherein, if the refractive index of one of the lenses in the cemented lens of the second lens group (3) is ND and the Abbe number is VD, then the following conditions are satisfied: 1.43 ≤ ND ≤ 1.60, 66 ≤ VD ≤ 95.

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