An imaging lens

Abstract

This invention relates to an imaging lens, comprising a front fixed group (1), a focusing group (2), a rear fixed group (3), and a filter (4) arranged sequentially along the optical axis from the object side to the image side; the focusing group (2) is movable back and forth along the optical axis; the front fixed group (1) has negative optical power, the focusing group (2) has positive optical power, and the rear fixed group (3) has positive optical power. The imaging lens of this invention provides more detailed imaging, a higher dynamic range, greater depth of field, and better color and contrast, resulting in a wider range of applications. Furthermore, the lens's relatively low distortion characteristics contribute to a wider field of view and a better large field-of-view effect.

Description

Technical Field

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

[0002] Machine vision is a comprehensive technology that includes image processing, mechanical engineering, control, electric lighting, optical imaging, sensors, analog and digital video technology, and computer hardware and software technology (image enhancement and analysis algorithms, image cards, I / O cards, etc.). A typical machine vision application system includes image capture, a light source system, an image digitization module, a digital image processing module, an intelligent judgment and decision-making module, and a mechanical control and 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 images are not delicate enough, their dynamic range is not high, and their color and contrast are not good enough. At the same time, their transmittance deviation is large. Such lenses are severely limited in the application of some high-precision and high-tech fields. Summary of the Invention

[0004] One object of the present invention is to provide an imaging lens that solves the problem of poor image quality.

[0005] To achieve the above objectives, the present invention provides an imaging lens, comprising a front fixing group, a focusing group, a rear fixing group, and a filter arranged sequentially along the optical axis from the object side to the image side;

[0006] The focusing group can reciprocate along the optical axis;

[0007] The front fixed group has negative optical power, the focusing group has positive optical power, and the rear fixed group has positive optical power.

[0008] According to one aspect of the invention, the front fixed assembly includes at least two negative power lenses and at least two positive power lenses.

[0009] According to one aspect of the invention, the focusing group includes at least one biconvex lens.

[0010] According to one aspect of the invention, the rear fixation group comprises at least two positive power lenses.

[0011] According to one aspect of the invention, the front fixed assembly includes at least five lenses, wherein, along the object-to-image direction, the first and fifth lenses are positive power lenses, and the second and third lenses are negative power lenses.

[0012] According to one aspect of the invention, along the object-to-image direction, the first lens, the second lens, and the third lens are convex-concave lenses, and the fifth lens is a concave-convex lens or a biconvex lens.

[0013] According to one aspect of the invention, along the image-to-object direction, the first and second rear lenses in the rear fixed group are positive power lenses.

[0014] According to one aspect of the invention, one of the two positive power lenses is a biconvex lens and the other is a cemented lens.

[0015] According to one aspect of the invention, if the focal length of the imaging lens is F and the focal length of the front group of the front fixed group is F1, then -70° is satisfied. <F1 / F<-5。

[0016] According to one aspect of the invention, if the focal length of the imaging lens is F and the focal length of the focusing group is F2, then the following condition is satisfied: 1.5 <F2 / F≤3.0。

[0017] According to one aspect of the present invention, if the focal length of the imaging lens is F and the maximum image plane range of the imaging lens is Φi, then the following condition is satisfied: 1.0 < Φi / F < 1.8.

[0018] According to one aspect of the invention, the second rear lens group includes a cemented lens made of an anomalous dispersion glass material, and the Abbe number VD of the cemented lens satisfies: 61. <VD<96。

[0019] According to one aspect of the invention, it further includes an aperture stop located between the front fixing group and the focusing group.

[0020] According to one aspect of the present invention, the imaging lens of the present invention provides more delicate imaging, a higher dynamic imaging range, a greater depth of field, and better color and contrast, thus having a wider range of applications. In addition, the lens itself has relatively small distortion characteristics, resulting in a wider field of view and a better large field of view effect.

[0021] According to one aspect of the present invention, the imaging lens of the present invention adopts a three-group structure, which better ensures that the imaging lens obtains high image quality close to the diffraction limit and uniform image quality; the front fixed group and the rear fixed group are positive and negative lens combinations, and the focusing group adopts at least one biconvex lens. The first lens of the front fixed group adopts a convex-concave lens with positive optical power, the second lens adopts a convex-concave lens with negative optical power, and the third lens adopts a convex-concave lens with negative optical power. This overall lens configuration is beneficial for reversing the optical path, achieving low distortion, easily ensuring a large image area, and balancing optical power.

[0022] According to one aspect of the present invention, by rationally matching the positive and negative optical power and the magnitude of optical power of the front fixed group and the entire imaging lens, it is possible to effectively avoid the degradation of focusing performance under different object distances and to easily reduce tolerance sensitivity.

[0023] According to one aspect of the present invention, by rationally matching the positive and negative optical power and the magnitude of optical power of the focusing group and the entire imaging lens, the degradation of focusing performance under different object distances can be effectively avoided and the tolerance sensitivity can be easily reduced.

[0024] According to one aspect of the present invention, the imaging lens of the present invention is guaranteed to have a larger image plane, thereby making the image more delicate, the dynamic imaging range higher, the color and contrast better, and the shallow depth of field effect better.

[0025] According to one aspect of the present invention, the rear fixed assembly employs a cemented lens on the image side and uses an aberrant dispersion material, which is beneficial for correcting chromatic aberration, while avoiding the deterioration of focusing performance at different object distances and facilitating the correction of high and low temperature performance. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the structure of an imaging lens according to Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the lens resolution of the imaging lens according to Embodiment 1 of the present invention;

[0028] Figure 3 This is a schematic representation of the lens lateral chromatic aberration diagram of the imaging lens according to Embodiment 1 of the present invention;

[0029] Figure 4 This is a schematic diagram illustrating the lens distortion of the imaging lens according to Embodiment 1 of the present invention;

[0030] Figure 5 This is a schematic diagram illustrating the defocus curve of the imaging lens according to Embodiment 1 of the present invention;

[0031] Figure 6 This is a schematic diagram illustrating the structure of the imaging lens according to Embodiment 2 of the present invention;

[0032] Figure 7 This is a schematic diagram illustrating the lens resolution of the imaging lens according to Embodiment 2 of the present invention;

[0033] Figure 8 This is a schematic representation of the lens lateral chromatic aberration diagram of the imaging lens according to Embodiment 2 of the present invention;

[0034] Figure 9 This is a schematic diagram illustrating the lens distortion of the imaging lens according to Embodiment 2 of the present invention;

[0035] Figure 10 This is a schematic diagram illustrating the defocus curve of the imaging lens according to Embodiment 2 of the present invention;

[0036] Figure 11 This is a schematic diagram illustrating the structure of the imaging lens according to Embodiment 3 of the present invention;

[0037] Figure 12 This is a schematic diagram illustrating the lens resolution of the imaging lens according to Embodiment 3 of the present invention;

[0038] Figure 13 This is a schematic representation of the lens lateral chromatic aberration diagram of the imaging lens according to Embodiment 3 of the present invention;

[0039] Figure 14 This is a schematic diagram illustrating the lens distortion of the imaging lens according to Embodiment 3 of the present invention;

[0040] Figure 15 This is a schematic diagram illustrating the defocus curve of the imaging lens according to Embodiment 3 of the present invention;

[0041] Figure 16 This is a schematic diagram illustrating the structure of the imaging lens according to Embodiment 4 of the present invention;

[0042] Figure 17 This is a schematic diagram illustrating the lens resolution of the imaging lens according to Embodiment 4 of the present invention;

[0043] Figure 18 This is a schematic representation of the lens lateral chromatic aberration diagram of the imaging lens according to Embodiment 4 of the present invention;

[0044] Figure 19 This is a schematic diagram illustrating the lens distortion of the imaging lens according to Embodiment 4 of the present invention;

[0045] Figure 20 This is a schematic diagram illustrating the defocus curve of the imaging lens according to Embodiment 4 of the present invention;

[0046] Figure 21 This is a schematic diagram illustrating the structure of the imaging lens according to Embodiment 5 of the present invention;

[0047] Figure 22 This is a schematic diagram illustrating the lens resolution of the imaging lens according to Embodiment 5 of the present invention;

[0048] Figure 23 This is a schematic representation of the lens lateral chromatic aberration diagram of the imaging lens according to Embodiment 5 of the present invention;

[0049] Figure 24 This is a schematic diagram illustrating the lens distortion of the imaging lens according to Embodiment 5 of the present invention;

[0050] Figure 25 This is a schematic diagram illustrating the defocus curve of the imaging lens according to Embodiment 5 of the present invention; Detailed Implementation

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0052] When describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" express orientations or positional relationships based on the orientations or positional relationships shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on the present invention.

[0053] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0054] like Figure 1 As shown, an imaging lens according to the present invention includes a front fixed group 1, a focusing group 2, a rear fixed group 3, and a filter 4 arranged sequentially along the optical axis from the object side to the image side. In this embodiment, the focusing group 2 is reciprocating along the optical axis. In this embodiment, the front fixed group 1 has negative optical power, the focusing group 2 has positive optical power, and the rear fixed group 3 has positive optical power. In this embodiment, the positions of the front fixed group 1 and the rear fixed group 3 are fixed, and the focusing group 2 moves back and forth to focus the imaging lens of the present invention at different object distances.

[0055] like Figure 1 As shown, according to one embodiment of the present invention, the front fixed assembly 1 includes at least two negative power lenses and at least two positive power lenses.

[0056] like Figure 1 As shown, according to one embodiment of the present invention, the focusing group 2 includes at least one biconvex lens.

[0057] like Figure 1 As shown, according to one embodiment of the present invention, the rear fixed assembly 3 includes at least two positive power lenses.

[0058] like Figure 1As shown, according to one embodiment of the present invention, one of the two positive power lenses in the rear fixed group 3 is a biconvex lens and the other is a cemented lens.

[0059] With the above configuration, the rear fixing group 3 uses a biconvex lens with positive optical power and a cemented lens, which is beneficial for correcting chromatic aberration and can avoid the deterioration of focusing performance under different object distances, and is easy to correct the high and low temperature performance of the present invention.

[0060] like Figure 1 As shown, according to one embodiment of the present invention, the front fixed assembly 1 includes at least five lenses, wherein, along the object-to-image direction, the first lens L1 and the fifth lens L5 are positive power lenses, and the second lens L2 and the third lens L3 are negative power lenses. In this embodiment, along the object-to-image direction, the first lens L1, the second lens L2, and the third lens L3 are convex-concave lenses, and the fifth lens L5 is a concave-convex lens or a biconvex lens.

[0061] With the above configuration, the imaging lens of the present invention adopts a three-group structure, which better ensures that the imaging lens obtains high image quality close to the diffraction limit and uniform image quality. The front fixed group and the rear fixed group are combined with positive and negative lenses, and the focusing group uses at least one biconvex lens. The first lens of the front fixed group is a convex-concave lens with positive optical power, the second lens is a convex-concave lens with negative optical power, and the third lens is a convex-concave lens with negative optical power. This overall lens configuration is beneficial for reversing the optical path, achieving low distortion, easily ensuring a large image area, and balancing optical power.

[0062] like Figure 1 As shown, according to one embodiment of the present invention, along the image-to-object direction, the first rear lens group and the second rear lens group in the rear fixed group 3 are positive power lenses.

[0063] With the above configuration, the lens closest to the image plane in the rear fixed group 3 (i.e., the first rear group lens along the direction from the image side to the object side) is a positive power lens, which is beneficial for correcting chromatic aberration and can avoid the deterioration of focusing performance under different object distances, and is easy to correct the high and low temperature performance of the present invention.

[0064] like Figure 1 As shown, according to one embodiment of the present invention, the focal length of the imaging lens is F, and the focal length of the front group 1 of the front fixed group is F1, then the following condition is satisfied: -70 <F1 / F<-5。

[0065] By setting up the above parameters and properly matching the positive and negative optical power and the magnitude of the optical power of the front fixed group and the entire imaging lens, it is possible to effectively avoid the degradation of focusing performance at different object distances and easily reduce tolerance sensitivity.

[0066] like Figure 1As shown, according to an embodiment of the present invention, the focal length of the imaging lens is F, and the focal length of the focusing group 2 is F2, then the following is satisfied: 1.5 < F2 / F ≤ 3.0.

[0067] Through the above settings, by reasonably matching the positive and negative optical powers and the magnitudes of the optical powers of the focusing group and the entire imaging lens, it is possible to well avoid the deterioration of the focusing performance at different object distances and easily reduce the tolerance sensitivity.

[0068] As Figure 1 shown, according to an embodiment of the present invention, the focal length of the imaging lens is F, and the maximum image plane range of the imaging lens is Φi, then the following is satisfied: 1.0 < Φi / F < 1.8.

[0069] Through the above settings, it is ensured that the imaging lens of the present invention has imaging with a larger image plane, thereby making the imaging more delicate, the dynamic imaging range higher, the color and contrast better, and the shallow depth-of-field effect better.

[0070] As Figure 1 shown, according to an embodiment of the present invention, the second rear lens group includes a cemented sub-lens made of an anomalous dispersion glass material, and the Abbe number VD of the cemented sub-lens satisfies: 61 < VD < 96. In this embodiment, the cemented sub-lens is arranged on the image side of the second rear lens group.

[0071] Through the above settings, the use of a cemented sub-lens arranged on the image side and an anomalous dispersion material in the rear fixed group is beneficial to correcting chromatic aberration, and at the same time can avoid the deterioration of the focusing performance at different object distances and is easy to correct the high and low temperature performance.

[0072] As Figure 1 shown, according to an embodiment of the present invention, an imaging lens of the present invention further includes an aperture 5, and the aperture 5 is located between the front fixed group 1 and the focusing group 2.

[0073] [[ID=...]] The following uses five groups of examples to specifically illustrate the imaging lens according to the present invention. The data in the five groups of examples are shown in Table 1 below:

[0074] Conditional expression Example 1 Example 2 Example 3 Example 4 Example 5 -70<F1 / F<-5 -18.6 -68.4 -8.73 -7.55 -6.18 1.5<F2 / F≤3.0 2.4 2.7 1.86 1.9 3.0 1.0<Φi / F<1.8 1.43 1.77 1.06 1.06 1.49 61<VD<96 62 70 82 90 95

[0075] Table 1 [[ID=...]]

[0076] As can be seen from Table 1, according to the settings of the various parameters in the five groups of examples of the imaging lens of the present invention, the requirements for the various parameter conditions of the imaging lens of the present invention are satisfied.

[0077] Figure 1 is a schematic diagram showing the structure of the imaging lens according to Embodiment 1 of the present invention. As Figure 1As shown, in this embodiment, the front fixed group 1 of the imaging lens includes six lenses, the focusing group 2 includes one lens, and the rear fixed group 3 includes four lenses. For ease of description, the optical surfaces are numbered according to the number of lenses. Since the lens is a cemented lens composed of multiple lenses bonded together, each cemented surface is numbered. Therefore, in this embodiment, they are numbered S1-S12 and S14-S21. Furthermore, the imaging system using the imaging lens of the present invention also includes an aperture stop surface STO and filter surfaces S22 and S24.

[0078] In this embodiment, the imaging lens of the present invention has a focal length F = 6.3 mm, a working distance WD = 50 mm to infinite, an aperture value FNO = 2.0, and a half field of view ω = 40°. Table 2 below lists the relevant parameters of each lens, including radius of curvature, thickness, material refractive index, and material Abbe number:

[0079]

[0080]

[0081] Table 2

[0082] It should be noted that S15 in the table is movable, which represents the movement of the focusing group.

[0083] Table 3 below lists the performance parameters obtained in this embodiment based on Table 1:

[0084] -70<F1 / F<-5 1.5<F2 / F≤3.0 1.0<Φi / F<1.8 61<VD<96 -18.6 2.4 1.43 62

[0085] Table 3

[0086] As can be seen from Tables 1, 2 and 3, in this embodiment, the settings of the relevant parameters of each lens meet the requirements of the imaging lens of the present invention. Figures 2-5 These are schematic diagrams illustrating the lens resolution, transverse chromatic aberration, lens distortion, and defocus curve of the imaging lens according to Embodiment 1 of the present invention. Figures 2-5 It can be seen that by arranging the imaging lens of the present invention according to the relevant parameters of each lens in Embodiment 1, the imaging lens of the present invention can have the characteristics of low distortion, large image size, and the advantages of being able to correct chromatic aberration and having excellent high and low temperature performance.

[0087] Figure 6 This is a schematic diagram illustrating the structure of the wide-angle end of the imaging lens according to Embodiment 2 of the present invention. Figure 6As shown, in this embodiment, the front fixed group 1 of the imaging lens includes six lenses, the focusing group 2 includes one lens, and the rear fixed group 3 includes four lenses. For ease of description, the optical surfaces are numbered according to the number of lenses. Since the lens is a cemented lens composed of multiple lenses bonded together, each cemented surface is numbered. Therefore, in this embodiment, they are numbered S1-S12 and S14-S21. Furthermore, the imaging system using the imaging lens of the present invention also includes an aperture stop surface STO and filter surfaces S22 and S24.

[0088] In this embodiment, the imaging lens of the present invention has a focal length F = 5.1 mm, a working distance WD = 50 mm to infinite, an aperture value FNO = 2.0, and a half field of view ω = 40°. Table 4 below lists the relevant parameters of each lens, including radius of curvature, thickness, material refractive index, and material Abbe number:

[0089]

[0090]

[0091] Table 4

[0092] Table 5 below lists the performance parameters obtained in this embodiment based on Table 1:

[0093] -70<F1 / F<-5 1.5<F2 / F≤3.0 1.0<Φi / F<1.8 61<VD<96 -68.4 2.7 1.77 70

[0094] Table 5

[0095] As can be seen from Tables 1, 4 and 5, in this embodiment, the settings of the relevant parameters of each lens meet the requirements of the imaging lens of the present invention. Figures 7-10 These are schematic diagrams illustrating the lens resolution, transverse chromatic aberration, lens distortion, and defocus curve of the imaging lens according to Embodiment 2 of the present invention. Figures 7-10 It can be seen that by arranging the imaging lens of the present invention according to the relevant parameters of each lens in Embodiment 2, the imaging lens of the present invention can have the characteristics of low distortion, large image size, and the advantages of being able to correct chromatic aberration and excellent high and low temperature performance.

[0096] Figure 11 This is a schematic diagram illustrating the structure of the wide-angle end of the imaging lens according to Embodiment 3 of the present invention. Figure 11As shown, in this embodiment, the front fixed group 1 of the imaging lens includes six lenses, the focusing group 2 includes one lens, and the rear fixed group 3 includes four lenses. For ease of description, the optical surfaces are numbered according to the number of lenses. Since the lens is a cemented lens composed of multiple lenses bonded together, each cemented surface is numbered. Therefore, in this embodiment, they are numbered S1-S12 and S14-S21. Furthermore, the imaging system using the imaging lens of the present invention also includes an aperture stop surface STO and filter surfaces S22 and S24.

[0097] In this embodiment, the imaging lens of the present invention has a focal length F = 8.5 mm, a working distance WD = 50 mm to infinite, an aperture value FNO = 2.0, and a half field of view ω = 40°. Table 6 below lists the relevant parameters of each lens, including radius of curvature, thickness, material refractive index, and material Abbe number:

[0098]

[0099]

[0100] Table 6

[0101] Table 7 below lists the performance parameters obtained in this embodiment based on Table 1:

[0102] -70<F1 / F<-5 1.5<F2 / F≤3.0 1.0<Φi / F<1.8 61<VD<96 -8.73 1.86 1.06 82

[0103] Table 7

[0104] As can be seen from Tables 1, 6, and 7, in this embodiment, the settings of the relevant parameters of each lens meet the requirements of the imaging lens of the present invention. Figures 12-15 These are schematic diagrams illustrating the lens resolution, transverse chromatic aberration, lens distortion, and defocus curve of the imaging lens according to Embodiment 3 of the present invention. Figures 12-15 It can be seen that by arranging the imaging lens of the present invention according to the relevant parameters of each lens in Embodiment 3, the imaging lens of the present invention can have the characteristics of low distortion, large image area, and the advantages of being able to correct chromatic aberration and excellent high and low temperature performance.

[0105] Figure 16 This is a schematic diagram illustrating the structure of the wide-angle end of the imaging lens according to Embodiment 4 of the present invention. Figure 16As shown, in this embodiment, the front fixed group 1 of the imaging lens includes six lenses, the focusing group 2 includes one lens, and the rear fixed group 3 includes four lenses. For ease of description, the optical surfaces are numbered according to the number of surfaces. Since the lens is a cemented lens composed of multiple lenses bonded together, each cemented surface is numbered. Therefore, in this embodiment, they are numbered S1-S12 and S14-S22. Furthermore, the imaging system using the imaging lens of the present invention also includes an aperture stop surface STO and filter surfaces S23 and S24.

[0106] In this embodiment, the imaging lens of the present invention has a focal length F = 6.0 mm, a working distance WD = 50 mm to infinity, an aperture FNO = 2.0, and a half field of view ω = 40°. Table 8 below lists the relevant parameters of each lens, including radius of curvature, thickness, material refractive index, and material Abbe number:

[0107]

[0108]

[0109]

[0110] Table 8

[0111] Table 9 below lists the performance parameters obtained in this embodiment based on Table 1:

[0112] -70<F1 / F<-5 1.5<F2 / F≤3.0 1.0<Φi / F<1.8 61<VD<96 -7.55 1.9 1.06 90

[0113] Table 9

[0114] As can be seen from Tables 1, 8 and 9, in this embodiment, the settings of the relevant parameters of each lens meet the requirements of the imaging lens of the present invention. Figures 17-20 These are schematic diagrams illustrating the lens resolution, transverse chromatic aberration, lens distortion, and defocus curve of the imaging lens according to Embodiment 4 of the present invention. Figures 17-20 It can be seen that by arranging the imaging lens of the present invention according to the relevant parameters of each lens in Embodiment 4, the imaging lens of the present invention can have the characteristics of low distortion, large image area, and the advantages of being able to correct chromatic aberration and excellent high and low temperature performance.

[0115] Figure 21 This is a schematic diagram illustrating the structure of the imaging lens according to Embodiment 5 of the present invention. Figure 21As shown, in this embodiment, the front fixed group 1 of the imaging lens includes six lenses, the focusing group 2 includes two lenses, and the rear fixed group 3 includes four lenses. For ease of description, the optical surfaces are numbered according to the number of surfaces. Since the lens is a cemented lens composed of multiple lenses bonded together, each cemented surface is numbered. Therefore, in this embodiment, they are numbered S1-S12 and S14-S23. Furthermore, the imaging system using the imaging lens of the present invention also includes an aperture stop surface STO and filter surfaces S24 and S25.

[0116] In this embodiment, the imaging lens of the present invention has a focal length F = 6mm, a working distance WD = 50mm to infinity, an aperture value FNO = 2.0, and a half field of view ω = 40°. Table 10 below lists the relevant parameters of each lens, including radius of curvature, thickness, material refractive index, and material Abbe number:

[0117]

[0118]

[0119] Table 10

[0120] Table 11 below lists the performance parameters obtained in this embodiment based on Table 1:

[0121] -70<F1 / F<-5 1.5<F2 / F≤3.0 1.0<Φi / F<1.8 61<VD<96 -6.18 3.0 1.49 95

[0122] Table 11

[0123] As can be seen from Tables 1, 10, and 11, in this embodiment, the settings of the relevant parameters of each lens meet the requirements of the imaging lens of the present invention. Figures 22-25 These are schematic diagrams illustrating the lens resolution, transverse chromatic aberration, lens distortion, and defocus curve of the imaging lens according to Embodiment 5 of the present invention. Figures 22-25 It can be seen that by arranging the imaging lens of the present invention according to the relevant parameters of each lens in Embodiment 5, the imaging lens of the present invention can have the characteristics of low distortion, large image size, and the advantages of being able to correct chromatic aberration and excellent high and low temperature performance.

[0124] The above description is merely an example of a specific solution of the present invention. For any devices and structures not described in detail herein, it should be understood that they are implemented using common devices and methods already available in the art.

[0125] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An imaging lens, characterized in that, It includes a front fixed group (1), a focusing group (2), a rear fixed group (3), and a filter (4) arranged sequentially along the optical axis from the object side to the image side, for a total of three lens groups; The focusing group (2) can reciprocate along the optical axis; The front fixed group (1) has negative optical power, the focusing group (2) has positive optical power, and the rear fixed group (3) has positive optical power. The front fixed group (1) consists of six lenses, with the optical powers of each lens being positive, negative, negative, negative, positive, and positive in sequence; the focusing group (2) consists of one lens with positive optical power or two lenses with positive optical power; the rear fixed group (3) consists of four lenses, with the optical powers of each lens being positive, negative, positive, and positive in sequence; or The front fixed group (1) consists of six lenses, with the optical power of each lens being positive, negative, negative, positive, positive, and negative in sequence; the focusing group (2) consists of one lens with positive optical power; and the rear fixed group (3) consists of four lenses, with the optical power of each lens being positive, negative, positive, and positive in sequence.

2. The imaging lens according to claim 1, characterized in that, The last lens in the focusing group (2) is a biconvex lens.

3. The imaging lens according to claim 1, characterized in that, Along the object-to-image direction, the first lens (L1), the second lens (L2), and the third lens (L3) in the front fixed group (1) are convex and concave lenses, and the fifth lens (L5) is a concave-convex lens or a biconvex lens.

4. The imaging lens according to claim 1, characterized in that, Along the image-to-object direction, the first three lenses in the rear fixed group (3) form the first rear lens group, and the last lens in the rear fixed group (3) forms the second rear lens group. The first rear lens group and the second rear lens group are positive power lenses.

5. The imaging lens according to claim 4, characterized in that, The first rear lens group is a cemented lens.

6. The imaging lens according to any one of claims 1 to 5, characterized in that, The focal length of the imaging lens is F, and the focal length of the front group of the front fixed group (1) is F1, then the following condition is met: -70 <F1 / F<-5。 7. The imaging lens according to any one of claims 1 to 5, characterized in that, The focal length of the imaging lens is F, and the focal length of the focusing group (2) is F2, then the following condition is met: 1.5 <F2 / F≤3.0。 8. The imaging lens according to any one of claims 1 to 5, characterized in that, The focal length of the imaging lens is F, and the maximum image plane range of the imaging lens is Φi, which satisfies: 1.0 < Φi / F < 1.

8.

9. The imaging lens according to claim 4 or 5, characterized in that, The first rear lens group includes a cemented lens made of an anomalous dispersion glass material, and the Abbe number VD of the cemented lens satisfies:

61. <VD<96。 10. The imaging lens according to claim 1, characterized in that, It also includes an aperture (5) located between the front fixed group (1) and the focusing group (2).

Images