Industrial lens

Abstract

The invention discloses an industrial lens which sequentially comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power and a fourth lens with negative focal power from an object side to an image side along an optical axis, the object side surface of the second lens is a convex surface; the third lens has negative focal power, and the image side surface of the third lens is a concave surface; the fourth lens has positive focal power; the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a concave surface; the sixth lens has positive focal power, and the image side surface of the sixth lens is a convex surface; the number of the lenses with focal power in the industrial lens is six; and the industrial lens satisfies the condition that fa / fb is greater than or equal to 1.61 and less than or equal to 4.22, fa is the combined effective focal length of the first lens to the third lens, and fb is the combined effective focal length of the fourth lens to the sixth lens.

Description

Technical Field

[0001] This application relates to the technical field of imaging lenses, and specifically, to an industrial lens. Background Art

[0002] Industrial lenses can be widely used in various barcode scans in fields such as parking management, payment, industry, and logistics management. As the application fields of industrial lenses become more and more extensive, the market demand for industrial lenses is also increasing. However, the existing industrial lenses generally have the disadvantage of complex lens structures, making it difficult to ensure low cost of the lenses, and at the same time, it is difficult to balance indicators such as a wide working object distance range, high resolution, low distortion, and high illuminance.

[0003] Therefore, in view of the above deficiencies of the prior art, the present invention provides an industrial lens with high cost performance that, on the basis of meeting a simple lens structure and low cost, still has a wide working object distance range, adapts to a large chip target surface, simultaneously balances high resolution and low distortion, and has high illuminance in each field of view within the working object distance range of 40 mm to infinity. Summary of the Invention

[0004] This application provides an industrial lens. Along the optical axis, the industrial lens sequentially includes from the object side to the image side: a first lens with positive optical power, whose object side is convex; a second lens with positive optical power, whose object side is convex; a third lens with negative optical power, whose image side is concave; a fourth lens with positive optical power; a fifth lens with negative optical power, whose object side is concave and image side is concave; a sixth lens with positive optical power, whose image side is convex; the number of lenses with optical power in the industrial lens is six; and the industrial lens satisfies: 1.61 ≤ fa / fb ≤ 4.22, where fa is the combined effective focal length of the first lens to the third lens, and fb is the combined effective focal length of the fourth lens to the sixth lens.

[0005] According to an exemplary embodiment of the present application, the image side of the first lens of the industrial lens is convex or concave or flat; the image side of the second lens is convex or concave or flat; the object side of the third lens is convex or concave or flat; the object side of the fourth lens is convex or concave or flat, and its image side is convex; the object side of the sixth lens is convex or concave or flat.

[0006] According to an exemplary embodiment of the present application, the industrial lens includes a diaphragm, and the diaphragm is located between the third lens and the fourth lens.

[0007] According to an exemplary embodiment of the present application, the industrial lens satisfies at least one of the following conditional expressions: 1.31 ≤ fa / f ≤ 2.78, 0.59 ≤ fb / f ≤ 0.90, where fa is the combined effective focal length of the first lens to the third lens, fb is the combined effective focal length of the fourth lens to the sixth lens, and f is the total effective focal length of the industrial lens.

[0008] According to an exemplary embodiment of the present application, the industrial lens satisfies at least one of the following conditional expressions: -9.55 mm ≤ (f2 + f3) * f23 / (f1 + f2 + f3) ≤ -2.77 mm, 0.53 ≤ ((nd1 + nd3) / nd2) * (f1 + f3) / fa ≤ 1.07, -1.01 ≤ f23 / fa ≤ -0.23, where fa is the combined effective focal length of the first lens to the third lens, f23 is the combined effective focal length of the second lens to the third lens, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, nd1 is the refractive index of the first lens, nd2 is the refractive index of the second lens, and nd3 is the refractive index of the third lens.

[0009] According to an exemplary embodiment of the present application, the industrial lens satisfies at least one of the following conditional expressions: 0.62 ≤ (f4 + f5 + f6) / fb ≤ 1.11, -2.26 ≤ (R32 / R51) * (f3 / f5) ≤ -0.13, -1.63 ≤ R5n / f5 ≤ -0.94, 0.36 ≤ TCbn_max / fbn ≤ 1.21, where f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, fb is the combined effective focal length of the fourth lens to the sixth lens, R32 is the radius of curvature of the image side of the third lens, R51 is the radius of curvature of the object side of the fifth lens, R5n is the minimum value of the absolute value of the radius of curvature of the object side or the image side of the fifth lens, TCbn_max is the maximum value of the center thickness of any one of the fourth lens, the fifth lens, and the sixth lens, and fbn is the minimum value of the absolute value of the effective focal length of any one of the fourth lens, the fifth lens, and the sixth lens.

[0010] According to an exemplary embodiment of the present application, the industrial lens satisfies at least one of the following conditional expressions: 1.20 ≤ (f1 + f6) / f ≤ 1.63, 4.61 ≤ (R11 + R21) * (f1 + f2) / |R62 * f6| ≤ 9.04, 6.32 mm -1 ≤ (vd4 + vd6) / f6 ≤ 10.05 mm -1, 0.11 ≤ (TCn_max - TCn_min) / TCn_sum ≤ 0.17, where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f6 is the effective focal length of the sixth lens, f is the total effective focal length of the industrial lens, R11 is the curvature radius of the object side surface of the first lens, R21 is the curvature radius of the object side surface of the second lens, R62 is the curvature radius of the image side surface of the sixth lens, vd4 is the Abbe number of the fourth lens, vd6 is the Abbe number of the sixth lens, TCn_max is the maximum value of the central thickness of any one of the first lens to the sixth lens, TCn_min is the minimum value of the central thickness of any one of the first lens to the sixth lens, and TCn_sum is the sum of the central thicknesses of the lenses from the first lens to the sixth lens.

[0011] According to an exemplary embodiment of the present application, the industrial lens satisfies at least one of the following conditional expressions: 10.03 mm ≤ fb*(TC4 + TC5 + TC6) / CTb ≤ 14.15 mm, 1.73 ≤ CTb / CTa ≤ 2.58, where fb is the combined effective focal length of the fourth lens to the sixth lens, TC4 is the central thickness of the fourth lens, TC5 is the central thickness of the fifth lens, TC6 is the central thickness of the sixth lens, CTa is the central distance from the object side surface of the first lens to the diaphragm surface, and CTb is the central distance from the diaphragm surface to the image side surface of the sixth lens.

[0012] According to an exemplary embodiment of the present application, the industrial lens satisfies at least one of the following conditional expressions: 1.78 ≤ fa / fb ≤ 3.84, 1.45 ≤ fa / f ≤ 2.53, 0.65 ≤ fb / f ≤ 0.82, -0.92 ≤ f23 / fa ≤ -0.26, -8.69 mm ≤ (f2 + f3)*f23 / (f1 + f2 + f3) ≤ -3.07 mm, 0.68 ≤ (f4 + f5 + f6) / fb ≤ 0.94, -2.06 ≤ (R32 / R51)*(f3 / f5) ≤ -0.24, -1.44 ≤ R5n / f5 ≤ -1.00, 0.58 ≤ ((nd1 + nd3) / nd2)*(f1 + f3) / fa ≤ 0.98, 1.31 ≤ (f1 + f6) / f ≤ 1.48, 5.11 ≤ (R11 + R21)*(f1 + f2) / |R62*f6| ≤ 8.23, 11.23 mm ≤ fb*(TC4 + TC5 + TC6) / CTb ≤ 12.87 mm, 0.40 ≤ TCbn_max / fbn ≤ 1.11, 7.03 mm -1 ≤ (vd4 + vd6) / f6 ≤ 9.14 mm -1, 0.11 ≤ (TCn_max - TCn_min) / TCn_sum ≤ 0.16, 1.92 ≤ CTb / CTa ≤ 2.35, where fa is the combined effective focal length of the first lens to the third lens, fb is the combined effective focal length of the fourth lens to the sixth lens, f is the total effective focal length of the industrial lens, f23 is the combined effective focal length of the second lens to the third lens, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, R11 is the curvature radius of the object side surface of the first lens, R21 is the curvature radius of the object side surface of the second lens, R32 is the curvature radius of the image side surface of the third lens, R51 is the curvature radius of the object side surface of the fifth lens, R62 is the curvature radius of the image side surface of the sixth lens, R5n is the minimum value of the absolute value of the curvature radius of the object side surface or the image side surface of the fifth lens, nd1 is the refractive index of the first lens, nd2 is the refractive index of the second lens, nd3 is the refractive index of the third lens, vd4 is the Abbe number of the fourth lens, vd6 is the Abbe number of the sixth lens, TC4 is the central thickness of the fourth lens, TC5 is the central thickness of the fifth lens, TC6 is the central thickness of the sixth lens, TCbn_max is the maximum value of the central thickness of any one of the fourth lens, the fifth lens and the sixth lens, fbn is the minimum value of the absolute value of the effective focal length of any one of the fourth lens, the fifth lens and the sixth lens, TCn_max is the maximum value of the central thickness of any one of the first lens to the sixth lens, TCn_min is the minimum value of the central thickness of any one of the first lens to the sixth lens, TCn_sum is the sum of the central thicknesses of the lenses from the first lens to the sixth lens, CTa is the central distance from the object side surface of the first lens to the diaphragm surface, and CTb is the central distance from the diaphragm surface to the image side surface of the sixth lens.

[0013] The industrial lens of the present application has the characteristics of simple structure, low cost, and a wide working object distance range (WD ≥ 40 mm) by reasonably setting the number of lenses (for example, six) and reasonably distributing the relationships among the optical powers, lens surface types, and lens parameters of each lens, and can be adapted to a large chip target surface (1 / 1.8" chip). At the same time, it takes into account high resolution and low distortion (optical distortion |DIS| ≤ 0.65%), and has a relatively high relative illuminance in each field of view in the working object distance range from 40 mm to infinity (relative illuminance > 88%). Description of the Drawings

[0014] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objects, and advantages of the present application will become more apparent:

[0015] Figure 1It is a schematic structural diagram of an industrial lens according to Embodiment 1 of the present application;

[0016] Figure 2 It is a distortion curve graph of an industrial lens according to Embodiment 1 of the present application;

[0017] Figure 3 It is a schematic structural diagram of an industrial lens according to Embodiment 2 of the present application;

[0018] Figure 4 It is a distortion curve graph of an industrial lens according to Embodiment 2 of the present application;

[0019] Figure 5 It is a schematic structural diagram of an industrial lens according to Embodiment 3 of the present application;

[0020] Figure 6 It is a distortion curve graph of an industrial lens according to Embodiment 3 of the present application;

[0021] Figure 7 It is a schematic structural diagram of an industrial lens according to Embodiment 4 of the present application;

[0022] Figure 8 It is a distortion curve graph of an industrial lens according to Embodiment 4 of the present application. Detailed implementation manners

[0023] To better understand the present application, more detailed descriptions of various aspects of the present application will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the exemplary embodiments of the present application and do not limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0024] It should be noted that in this specification, the expressions such as first, second, and third are only used to distinguish one feature from another feature and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0025] In the accompanying drawings, for the sake of clarity, the thickness, size, and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn to an exact scale.

[0026] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object being photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0027] It should also be understood that terms such as "comprising", "having", "including", etc., when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features, rather than an individual element in the list. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0028] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0029] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0030] According to an exemplary embodiment of the present application, an industrial lens may sequentially include six lenses with optical power along the optical axis from the object side to the image side, namely, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens.

[0031] In an exemplary embodiment, the first lens of the industrial lens has a positive optical power. The object side surface of the first lens may be convex, and the image side surface may be convex, concave, or flat. Such a setting can effectively converge the incident light, can diverge the large field of view light entering the optical system to the rear optical system, can effectively increase the light transmission amount, and improve the illuminance of the optical system.

[0032] In an exemplary embodiment, the second lens of the industrial lens has positive optical power. The object side surface of the second lens may be convex, and the image side surface may be convex, concave or flat. The third lens of the industrial lens has negative optical power. The object side surface of the third lens may be convex, concave or flat, and the image side surface may be concave. The second lens and the third lens may form a doublet. Such an arrangement can reduce the incident angle of light on the second lens and the third lens, thereby effectively reducing the tolerance sensitivity between the second lens and the third lens, ensuring the production yield of the lens; at the same time, the light is smoothly transitioned, spherical aberration is effectively corrected, and axial chromatic aberration can also be corrected to improve the resolution of the lens.

[0033] In an exemplary embodiment, the fourth lens of the industrial lens has positive focal power. The object side of the fourth lens can be convex, concave or flat, and the image side is convex. Such a setting can effectively control the trend of light, make the light transition smoothly, effectively reduce the tolerance sensitivity of the lens, and improve the quality of the lens. At the same time, the fourth lens can be made of a glass lens material with a low Abbe number, which is matched with the third lens which is also made of a glass lens material with a low Abbe number, which is conducive to balancing astigmatism and improving the resolution performance of the lens.

[0034] In an exemplary embodiment, the fifth lens of the industrial lens has negative optical power. The object side of the fifth lens can be concave, and the image side can be concave. Such a setting is conducive to balancing the aberration of the peripheral field of view of the industrial lens, while correcting the distortion, and realizing the low distortion characteristics of the lens; at the same time, it also effectively controls the light trend, further raises the light, and helps to achieve a large target surface of the lens.

[0035] In an exemplary embodiment, the sixth lens of the industrial lens has positive focal power. The object side of the sixth lens can be convex, concave or flat, and the image side is convex. Such a setting effectively controls the trend of light, so that the light smoothly transitions to the image plane, and effectively controls the exit angle of light passing through the sixth lens, which is conducive to matching the chip CRA and helps to achieve a large target surface of the lens. At the same time, the sixth lens can use a glass lens material with a high Abbe number, which can be matched with the fifth lens using a glass lens material with a low Abbe number. By matching lens materials with high and low Abbe numbers, it is helpful to correct the chromatic aberration and field curvature of the optical system and improve the quality of the lens.

[0036] In the exemplary embodiment, since the curvature radii of the image side surface of the first lens, the image side surface of the second lens, the object side surface of the fourth lens, and the object side surface of the sixth lens are all relatively large, it is easy to change or fine-tune the convex surface, the flat surface, and the concave surface, which usually has little impact on the overall technical effect of the optical system. Those skilled in the art can use a larger curvature radius as the optimization boundary condition for the surface, which obviously does not require creative work.

[0037] In an exemplary embodiment, the industrial lens satisfies: 1.61 ≤ fa / fb ≤ 4.22, where fa is the combined effective focal length of the first lens to the third lens, and fb is the combined effective focal length of the fourth lens to the sixth lens. By reasonably allocating the ratio relationship between the combined effective focal length of the first lens to the third lens and the combined effective focal length of the fourth lens to the sixth lens, it is beneficial to reasonably configure the relationship between the combined effective focal lengths of the lenses before and after the aperture in the optical system, which helps to ensure that the industrial lens achieves a wide working object distance range, effectively reduces the chromatic aberration generated by the optical system, and at the same time can effectively correct distortion, so that the industrial lens achieves low distortion in all working object distance ranges from 40 mm to infinity, and can also take into account the high resolution of the lens. More specifically, the industrial lens can also satisfy 1.78 ≤ fa / fb ≤ 3.84.

[0038] In an exemplary embodiment, the industrial lens satisfies: 1.31 ≤ fa / f ≤ 2.78, where fa is the combined effective focal length of the first lens to the third lens, and f is the total effective focal length of the industrial lens. By reasonably controlling the ratio relationship between the combined effective focal length of the first lens to the third lens and the total effective focal length of the industrial lens, the trend of light is effectively controlled, the aberration generated when light passes through the first lens to the third lens of the optical system is balanced, and the imaging quality of the lens is improved; at the same time, it also helps to correct distortion, so that the industrial lens achieves the characteristics of low distortion and high resolution in all working object distance ranges from 40 mm to infinity. More specifically, the industrial lens can also satisfy 1.45 ≤ fa / f ≤ 2.53.

[0039] In an exemplary embodiment, the industrial lens satisfies: 0.59 ≤ fb / f ≤ 0.90, where fb is the combined effective focal length of the fourth lens to the sixth lens, and f is the total effective focal length of the industrial lens. By reasonably controlling the ratio relationship between the combined effective focal length of the fourth lens to the sixth lens and the total effective focal length of the industrial lens, the system chromatic aberration can be effectively reduced and the lens resolution can be improved; at the same time, it also helps to correct distortion, so that the industrial lens achieves the characteristics of low distortion and high resolution in all working object distance ranges from 40 mm to infinity. More specifically, the industrial lens can also satisfy 0.65 ≤ fb / f ≤ 0.82.

[0040] In an exemplary embodiment, the industrial lens satisfies: -1.01 ≤ f23 / fa ≤ -0.23, where fa is the combined effective focal length of the first lens to the third lens, and f23 is the combined effective focal length of the second lens to the third lens. By reasonably matching the ratio relationship between the combined effective focal length of the second lens to the third lens and the combined effective focal length of the first lens to the third lens, it is beneficial to control the light trend, make the light transition smoothly, effectively reduce the tolerance sensitivity between the lenses, and contribute to improving the production yield of the lens; at the same time, it can also balance the overall aberration and improve the lens quality. More specifically, the industrial lens may further satisfy -0.92 ≤ f23 / fa ≤ -0.26.

[0041] In an exemplary embodiment, the industrial lens satisfies: 0.53 ≤ ((nd1 + nd3) / nd2) * (f1 + f3) / fa ≤ 1.07, where f1 is the effective focal length of the first lens, f3 is the effective focal length of the third lens, fa is the combined effective focal length of the first lens to the third lens, nd1 is the refractive index of the first lens, nd2 is the refractive index of the second lens, and nd3 is the refractive index of the third lens. By satisfying the above conditional relationship, it is beneficial to control the light trend, make the light transition smoothly, and contribute to ensuring that the industrial lens can achieve a wide object distance range from 40 mm to infinity, effectively reducing the tolerance sensitivity between the lenses, and improving the production yield of the lens; at the same time, it can also balance the overall aberration and improve the lens quality. More specifically, the industrial lens may further satisfy 0.58 ≤ ((nd1 + nd3) / nd2) * (f1 + f3) / fa ≤ 0.98.

[0042] In an exemplary embodiment, the industrial lens satisfies: -9.55 mm ≤ (f2 + f3) * f23 / (f1 + f2 + f3) ≤ -2.77 mm, where f23 is the combined effective focal length of the second lens to the third lens, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, and f3 is the effective focal length of the third lens. By satisfying the above conditional relationship, it is beneficial to control the light trend, make the light transition smoothly, effectively reduce the tolerance sensitivity between the lenses, and contribute to improving the production yield of the lens; at the same time, it can also effectively balance the aberration of the optical system, correct the chromatic aberration, improve the color reproducibility of the lens, and ensure the high quality of the lens. More specifically, the industrial lens may further satisfy -8.69 mm ≤ (f2 + f3) * f23 / (f1 + f2 + f3) ≤ -3.07 mm.

[0043] In an exemplary embodiment, the industrial lens satisfies: 0.62 ≤ (f4 + f5 + f6) / fb ≤ 1.11, where f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, and fb is the combined effective focal length of the fourth lens to the sixth lens. By satisfying the above conditional relationship, it is beneficial to control the light path, make the light transition smoothly, effectively balance the aberration of the optical system, and improve the resolution performance of the lens; at the same time, it also makes the light transition smoothly to the image plane, effectively controls the exit angle of the light passing through the fourth lens to the sixth lens, is beneficial to matching the chip CRA, and helps to achieve a large target surface of the lens. More specifically, the industrial lens may further satisfy 0.68 ≤ (f4 + f5 + f6) / fb ≤ 0.94.

[0044] In an exemplary embodiment, the industrial lens satisfies: -2.26 ≤ (R32 / R51)*(f3 / f5) ≤ -0.13, where R32 is the radius of curvature of the image side of the third lens, R51 is the radius of curvature of the object side of the fifth lens, f3 is the effective focal length of the third lens, and f5 is the effective focal length of the fifth lens. By satisfying the above conditional relationship, it is beneficial to adjust the incident angle and exit angle of the light passing through the lenses before and after the aperture, effectively control the light path, reduce the tolerance sensitivity, and improve the lens quality. More specifically, the industrial lens may further satisfy -2.06 ≤ (R32 / R51)*(f3 / f5) ≤ -0.24.

[0045] In an exemplary embodiment, the industrial lens satisfies: -1.63 ≤ R5n / f5 ≤ -0.94, where R5n is the minimum value of the absolute value of the radius of curvature of the object side or image side of the fifth lens, and f5 is the effective focal length of the fifth lens. By controlling the ratio relationship between the minimum value of the absolute value of the radius of curvature of the object side or image side of the fifth lens and the effective focal length of the fifth lens, it is possible to effectively control the light path, balance the aberration of the peripheral field of view, and improve the resolution performance of the industrial lens within all working object distance ranges from 40 mm to infinity; at the same time, it can further raise the light, which helps to achieve a large target surface of the lens. More specifically, the industrial lens may further satisfy -1.44 ≤ R5n / f5 ≤ -1.00.

[0046] In an exemplary embodiment, the industrial lens satisfies: 10.03 mm ≤ fb*(TC4 + TC5 + TC6) / CTb ≤ 14.15 mm, where fb is the combined effective focal length of the fourth lens to the sixth lens, TC4 is the central thickness of the fourth lens, TC5 is the central thickness of the fifth lens, TC6 is the central thickness of the sixth lens, and CTb is the central distance from the diaphragm plane to the image side surface of the sixth lens. By satisfying the above conditional relationship, the high-order aberrations generated when light passes through the first lens to the third lens can be effectively corrected, the field curvature and chromatic aberration can be corrected, and the image resolution quality of the lens can be improved; at the same time, it is also helpful to achieve a large target surface for the lens. More specifically, the industrial lens can also satisfy 11.23 mm ≤ fb*(TC4 + TC5 + TC6) / CTb ≤ 12.87 mm.

[0047] In an exemplary embodiment, the industrial lens satisfies: 0.36 ≤ TCbn_max / fbn ≤ 1.21, where TCbn_max is the maximum value of the central thickness of any one of the fourth lens, the fifth lens, and the sixth lens, and fbn is the minimum value of the absolute value of the effective focal length of any one of the fourth lens, the fifth lens, and the sixth lens. By satisfying the above conditional relationship, it is beneficial to correct the chromatic aberration and field curvature of the optical system, and at the same time, it can effectively control the light path, reduce the tolerance sensitivity, and improve the production yield of the lens. More specifically, the industrial lens can also satisfy 0.40 ≤ TCbn_max / fbn ≤ 1.11.

[0048] In an exemplary embodiment, the industrial lens satisfies: 1.20 ≤ (f1 + f6) / f ≤ 1.63, where f1 is the effective focal length of the first lens, f6 is the effective focal length of the sixth lens, and f is the total effective focal length of the industrial lens. By reasonably controlling the ratio relationship between the sum of the effective focal lengths of the two lenses, the first lens and the sixth lens, of the optical system and the effective focal length of the system, the incident angle and the exit angle of light can be effectively controlled, so that the light can reach the image plane smoothly within the range of all working object distances from 40 mm to infinity for this industrial lens, which helps to increase the light transmission amount of the optical system and achieve high illuminance of the lens; at the same time, it helps to balance the astigmatism of the optical system and reduce the distortion, and achieve the characteristics of high image resolution and low distortion of the lens. More specifically, the industrial lens can also satisfy 1.31 ≤ (f1 + f6) / f ≤ 1.48.

[0049] In an exemplary embodiment, the industrial lens satisfies: 4.61 ≤ (R11 + R21) * (f1 + f2) / |R62 * f6| ≤ 9.04, where R11 is the radius of curvature of the object side of the first lens, R21 is the radius of curvature of the object side of the second lens, R62 is the radius of curvature of the image side of the sixth lens, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, and f6 is the effective focal length of the sixth lens. By satisfying the above conditional relationship, it is beneficial to adjust the incident angle and the exit angle of the light passing through the lenses before and after the aperture, effectively control the light trend, reduce the tolerance sensitivity, and improve the lens quality. More specifically, the industrial lens may further satisfy 5.11 ≤ (R11 + R21) * (f1 + f2) / |R62 * f6| ≤ 8.23.

[0050] In an exemplary embodiment, the industrial lens satisfies: 6.32 mm -1 ≤ (vd4 + vd6) / f6 ≤ 10.05 mm -1 , where vd4 is the Abbe number of the fourth lens, vd6 is the Abbe number of the sixth lens, and f is the total effective focal length of the industrial lens. Reasonably allocating the ratio relationship between the sum of the Abbe numbers of the glass materials of the fourth lens and the sixth lens and the effective focal length of the sixth lens is beneficial to correcting chromatic aberration while effectively controlling the exit angle of the light, making the light reach the image plane smoothly, and facilitating large target surface imaging. Exemplarily, the industrial lens may further satisfy 7.03 mm -1 ≤ (vd4 + vd6) / f6 ≤ 9.14 mm -1 .

[0051] In an exemplary embodiment, the industrial lens satisfies: 0.11 ≤ (TCn_max - TCn_min) / TCn_sum ≤ 0.17, where TCn_max is the maximum value of the central thickness of any one of the first lens to the sixth lens, TCn_min is the minimum value of the central thickness of any one of the first lens to the sixth lens, and TCn_sum is the sum of the central thicknesses of the lenses from the first lens to the sixth lens. By satisfying the above conditional relationship, while achieving high resolution, it is also possible to compress the lens volume to a certain extent, reduce the weight of the lens, and realize the feature of lens miniaturization. Exemplarily, the industrial lens may further satisfy 0.11 ≤ (TCn_max - TCn_min) / TCn_sum ≤ 0.16.

[0052] In an exemplary embodiment, the industrial lens satisfies: 1.73 ≤ CTb / CTa ≤ 2.58, where CTa is the central distance from the object side surface of the first lens to the diaphragm surface, and CTb is the central distance from the diaphragm surface to the image side surface of the sixth lens. Reasonably controlling the ratio relationship between the central distance from the diaphragm surface to the image side surface of the sixth lens and the central distance from the object side surface of the first lens to the diaphragm surface helps ensure that the industrial lens achieves a wide working object distance range, can better balance the aberrations generated in the working object distance range from 40 mm to infinity, minimizes the overall diameter of the circle of confusion, and thus optimizes the resolution. Exemplarily, the industrial lens may also satisfy 1.92 ≤ CTb / CTa ≤ 2.35.

[0053] In an exemplary embodiment, each of the first lens to the sixth lens included in the industrial lens of the present application may be a spherical lens or an aspherical lens. As needed, the present application does not specifically limit the specific number of spherical lenses and aspherical lenses. When focusing on reflecting the imaging quality, the number of aspherical lenses can be increased, and even all lenses can be aspherical lenses. The characteristic of an aspherical lens is that the curvature continuously changes from the center to the periphery of the lens. Different from a spherical lens with a constant curvature from the center to the periphery of the lens, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate the aberrations that occur during imaging as much as possible, thereby improving the imaging quality of the lens. However, those skilled in the art should understand that without departing from the technical solution claimed in the present application, the lens surface types constituting the industrial lens can be changed to obtain the various results and advantages described in this specification. As an example, all of the first lens to the sixth lens in the present application are spherical lenses.

[0054] Those skilled in the art should understand that the refractive index temperature coefficient dn / dt and abnormal dispersion of plastics are relatively large. Reasonably matching an appropriate amount of plastic material is beneficial for high and low temperature balance, but too many plastic lenses are not conducive to system stability. The optical lens made of glass can suppress the shift of the back focal length of the optical lens with temperature change to improve system stability; at the same time, using glass material can avoid the problem that the imaging of the lens is blurred due to the high and low temperature changes in the use environment, which affects the normal use of the lens. Using glass material is beneficial for the lens to achieve athermalization. In addition, using glass material can also better correct the chromatic aberration of the system, improve the resolution of the lens, and at the same time reduce the generation of ghost images. As an example, all of the first lens to the sixth lens in the present application use glass material, which is beneficial for balancing the high and low temperature performance of the industrial lens and achieving high imaging quality within the range of -30°C to +70°C; at the same time, it is beneficial for controlling the light path, reducing the tolerance sensitivity, and achieving large target surface imaging.

[0055] The industrial lens of the present application may further include a diaphragm for restricting light beams. The diaphragm is beneficial to converging the light rays entering the optical lens, reducing the maximum clear aperture of the optical lens, and reducing the assembly sensitivity of the optical system. At the same time, it effectively balances the overall aberration, especially the balance of spherical aberration and coma, so as to further improve the imaging quality of the optical lens. It should be noted that the diaphragm can be set at any position between or on one side of any lenses according to actual needs. Exemplarily, the diaphragm is set between the third lens and the fourth lens.

[0056] The industrial lens of the present application may also include a filter having an object side and an image side and / or a protective glass having an object side and an image side. The filter can be used to correct color deviation, and the protective glass can be used to protect the image sensing chip located at the imaging surface.

[0057] The image height H corresponding to the maximum field of view angle of the industrial lens of the present application may satisfy: 8.81 mm ≤ H ≤ 9.6 mm. It can match the 1 / 1.8" chip size to achieve large target surface imaging of the lens.

[0058] The working object distance range of the industrial lens of the present application may satisfy: WD ≥ 40 mm. It can achieve a wide working object distance range of the lens.

[0059] The industrial lens of the present application has excellent resolution. When the spatial frequency is 125 lp / mm, the MTF values of the central field of view at all working object distances are above 0.26; the relative illuminance values of the entire field of view at all working object distances are above 88%.

[0060] However, those skilled in the art should understand that without departing from the technical solutions claimed in the present application, the number of lenses constituting the industrial lens can be changed to obtain the various results and advantages described in this specification. For example, although six lenses are described as an example in the embodiment, the industrial lens is not limited to including six lenses. If necessary, the industrial lens may also include other numbers of lenses.

[0061] The following further describes specific embodiments of the industrial lens applicable to the above embodiments with reference to the drawings.

[0062] Embodiment 1

[0063] Figure 1 A schematic structural diagram of the industrial lens according to Embodiment 1 of the present application is shown. As Figure 1 shown, the industrial lens sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 along the optical axis from the object side to the image side.

[0064] The first lens L1 has a positive optical power. Its object side S1 is a convex surface, and its image side S2 is a concave surface.

[0065] The second lens L2 has a positive optical power, its object side S3 is convex, and its image side S4 is concave.

[0066] The third lens L3 has a negative optical power, its object side S4 is convex, and its image side S5 is concave.

[0067] The fourth lens L4 has a positive optical power, its object side S6 is convex, and its image side S7 is convex.

[0068] The fifth lens L5 has a negative optical power, its object side S8 is concave, and its image side S9 is concave.

[0069] The sixth lens L6 has a positive optical power, its object side S10 is convex, and its image side S11 is convex.

[0070] Among them, the second lens L2 and the third lens L3 form a doublet lens.

[0071] The industrial lens further includes a diaphragm STO, and the diaphragm STO can be disposed between the third lens L3 and the fourth lens L4. It should be noted that the surfaces S1 to S11 are not shown in Figure 1 herein.

[0072] Table 1 shows the basic parameter table of the industrial lens of Embodiment 1, wherein the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0073] Table 1

[0074]

[0075]

[0076] In Embodiment 1, the object sides and the image sides of all the lenses from the first lens to the sixth lens are spherical surfaces.

[0077] For the industrial lens of this Embodiment 1, when the spatial frequency is 125 lp / mm, the MTF values of the central field of view under the working object distances from 40 mm to infinity are all above 0.28, and the MTF curve decreases uniformly and smoothly from the center to the edge field of view, indicating that the industrial lens has good imaging quality and good detail resolution ability; and, under the working object distances from 40 mm to infinity, the minimum relative illumination of the industrial lens is 90%, indicating that the industrial lens has a high relative illumination.

[0078] Figure 2 shows the distortion curve graph of the industrial lens of Embodiment 1, which represents the maximum optical distortion corresponding to the working object distances from 40 mm to infinity. It can be seen from the figure that the absolute value of the optical distortion of the edge field of view of this Embodiment 1 is 0.53% (the reference wavelength is 0.546 nm). According to Figure 2It can be seen that the industrial lens given in Embodiment 1 has the characteristic of low distortion and can achieve good imaging quality.

[0079] Embodiment 2

[0080] Figure 3 Fig. shows a schematic structural diagram of the industrial lens according to Embodiment 2 of the present application. As Figure 3 shown, the industrial lens sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 along the optical axis from the object side to the image side.

[0081] The first lens L1 has a positive optical power, its object side surface S1 is a convex surface, and its image side surface S2 is a concave surface.

[0082] The second lens L2 has a positive optical power, its object side surface S3 is a convex surface, and its image side surface S4 is a concave surface.

[0083] The third lens L3 has a negative optical power, its object side surface S4 is a convex surface, and its image side surface S5 is a concave surface.

[0084] The fourth lens L4 has a positive optical power, its object side surface S6 is a convex surface, and its image side surface S7 is a convex surface.

[0085] The fifth lens L5 has a negative optical power, its object side surface S8 is a concave surface, and its image side surface S9 is a concave surface.

[0086] The sixth lens L6 has a positive optical power, its object side surface S10 is a convex surface, and its image side surface S11 is a convex surface.

[0087] Among them, the second lens L2 and the third lens L3 form a doublet lens.

[0088] The industrial lens further includes a diaphragm STO, and the diaphragm STO can be disposed between the third lens L3 and the fourth lens L4. It should be noted that the surfaces S1 to S11 are not shown in Figure 3 herein.

[0089] Table 2 shows the basic parameter table of the industrial lens of Embodiment 2, wherein the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0090] Table 2

[0091]

[0092] In Embodiment 2, the object side surfaces and the image side surfaces of all the lenses from the first lens to the sixth lens are spherical surfaces.

[0093] In this Example 2, when the spatial frequency of the industrial lens is 125 lp / mm, the MTF values of the central field of view at the working object distances from 40 mm to infinity are all above 0.30, and the MTF curve decreases uniformly and smoothly from the center to the edge field of view, indicating that the industrial lens has good imaging quality and good detail resolution ability; moreover, at the working object distances from 40 mm to infinity, the minimum relative illumination of the industrial lens is 91%, indicating that the industrial lens has a high relative illumination.

[0094] Figure 4 The distortion curve graph of the industrial lens of Example 2 is shown, which represents the maximum optical distortion corresponding at the working object distances from 40 mm to infinity. It can be seen from the figure that the absolute value of the optical distortion of the edge field of view of this Example 2 is 0.65% (the reference wavelength is 0.546 nm). According to Figure 4 it can be known that the industrial lens given in Example 2 has the characteristic of low distortion and can achieve good imaging quality.

[0095] Example 3

[0096] Figure 5 The structural schematic diagram of the industrial lens of Embodiment 3 of the present application is shown. As Figure 5 shown, the industrial lens sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 along the optical axis from the object side to the image side.

[0097] The first lens L1 has a positive optical power, its object side surface S1 is a convex surface, and its image side surface S2 is a concave surface.

[0098] The second lens L2 has a positive optical power, its object side surface S3 is a convex surface, and its image side surface S4 is a convex surface.

[0099] The third lens L3 has a negative optical power, its object side surface S4 is a concave surface, and its image side surface S5 is a concave surface.

[0100] The fourth lens L4 has a positive optical power, its object side surface S6 is a concave surface, and its image side surface S7 is a convex surface.

[0101] The fifth lens L5 has a negative optical power, its object side surface S8 is a concave surface, and its image side surface S9 is a concave surface.

[0102] The sixth lens L6 has a positive optical power, its object side surface S10 is a concave surface, and its image side surface S11 is a convex surface.

[0103] Among them, the second lens L2 and the third lens L3 form a doublet lens.

[0104] The industrial lens further includes a stop STO, and the stop STO can be arranged between the third lens L3 and the fourth lens L4. It should be noted that the surfaces S1 to S11 are inFigure 5 is not shown.

[0105] Table 3 shows the basic parameter table of the industrial lens of Example 3, where the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0106] Table 3

[0107]

[0108] In Example 3, the object side and the image side of all the lenses from the first lens to the sixth lens are spherical surfaces.

[0109] For the industrial lens of this Example 3, when the spatial frequency is 125 lp / mm, the MTF values of the central field of view under the working object distances from 40 mm to infinity are all above 0.28, and during the process from the center to the edge field of view, the MTF curve decreases uniformly and smoothly, indicating that the industrial lens has good imaging quality and good detail resolution ability; moreover, under the working object distances from 40 mm to infinity, the minimum relative illumination of the industrial lens is 92%, indicating that the industrial lens has a high relative illumination.

[0110] Figure 6 shows the distortion curve graph of the industrial lens of Example 3, which represents the maximum optical distortion corresponding to the working object distances from 40 mm to infinity. It can be seen from the figure that the absolute value of the optical distortion of the edge field of view of this Example 3 is 0.59% (the reference wavelength is 0.546 nm). According to Figure 6 it can be known that the industrial lens given in Example 3 has the characteristic of low distortion and can achieve good imaging quality.

[0111] Example 4

[0112] Figure 7 shows the structural schematic diagram of the industrial lens of Embodiment 4 of the present application. As Figure 7 shown, the industrial lens sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 along the optical axis from the object side to the image side.

[0113] The first lens L1 has a positive optical power, its object side S1 is a convex surface, and its image side S2 is a concave surface.

[0114] The second lens L2 has a positive optical power, its object side S3 is a convex surface, and its image side S4 is a convex surface.

[0115] The third lens L3 has a negative optical power, its object side S4 is a concave surface, and its image side S5 is a concave surface.

[0116] The fourth lens L4 has a positive optical power, its object side S6 is a convex surface, and its image side S7 is a convex surface.

[0117] The fifth lens L5 has a negative optical power, its object side S8 is concave, and its image side S9 is concave.

[0118] The sixth lens L6 has a positive optical power, its object side S10 is convex, and its image side S11 is convex.

[0119] Among them, the second lens L2 and the third lens L3 form a doublet lens.

[0120] The industrial lens further includes a diaphragm STO, and the diaphragm STO can be disposed between the third lens L3 and the fourth lens L4. It should be noted that the surfaces S1 to S11 are not shown in Figure 7 herein.

[0121] Table 4 shows the basic parameter table of the industrial lens of Embodiment 4, wherein the units of the radius of curvature and the thickness / distance are both millimeters (mm).

[0122] Table 4

[0123]

[0124] In Embodiment 4, the object sides and the image sides of all the lenses from the first lens to the sixth lens are spherical surfaces.

[0125] For the industrial lens of this Embodiment 4, when the spatial frequency is 125 lp / mm, the MTF values of the central field of view under the working object distances from 40 mm to infinity are all above 0.28, and the MTF curve uniformly and smoothly decreases during the process from the center to the edge field of view, indicating that the industrial lens has good imaging quality and good detail resolution ability; and, under the working object distances from 40 mm to infinity, the minimum relative illumination of the industrial lens is 91%, indicating that the industrial lens has a high relative illumination.

[0126] Figure 8 shows the distortion curve graph of the industrial lens of Embodiment 4, which represents the maximum optical distortion corresponding to the working object distances from 40 mm to infinity. It can be seen from the figure that the absolute value of the optical distortion of the edge field of view of this Embodiment 4 is 0.58% (the reference wavelength is 0.546 nm). According to Figure 8 it can be known that the industrial lens given in Embodiment 4 has the characteristic of low distortion and can achieve good imaging quality.

[0127] In summary, the industrial lenses in Embodiments 1 to 4 respectively satisfy the relationships shown in Table 5. Among them, in Table 5, the parameters nd1, nd2, nd3, vd4, and vd6 have no units, and the units of the remaining parameters are millimeters (mm).

[0128] Table 5

[0129] Conditional / Example 1 2 3 4 f 21.890 21.950 21.950 21.950 fa / fb 3.835 1.784 3.232 3.306 fa / f 2.526 1.454 2.179 2.249 fb / f 0.659 0.815 0.674 0.680 f23 / fa -0.261 -0.919 -0.302 -0.302 (f2 + f3) * f23 / (f1 + f2 + f3) -3.500 -8.682 -3.073 -3.097 (f4 + f5 + f6) / fb 0.845 0.684 0.939 0.906 (R32 / R51) * (f3 / f5) -0.558 -2.059 -0.243 -0.329 R5n / f5 -1.251 -1.436 -1.040 -1.094 ((nd1 + nd3) / nd2) * (f1 + f3) / fa 0.585 0.974 0.680 0.674 (f1 + f6) / f 1.329 1.478 1.382 1.369 (R11 + R21) * (f1 + f2) / |R62 * f6| 6.506 8.221 5.119 5.606 fb * (TC4 + TC5 + TC6) / CTb 11.563 12.863 11.235 11.410 TCbn_max / fbn 0.773 1.102 0.483 0.565 (vd4 + vd6) / f6 9.137 8.667 7.025 7.449 (TCn_max - TCn_min) / TCn_sum 0.141 0.155 0.119 0.132 CTb / CTa 1.927 2.347 2.020 2.029

[0130] The above description is only a preferred embodiment of the present application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) disclosed in the present application that have similar functions.

Claims

1. Industrial lens, characterized in that, It includes, in order from the object side to the image side along the optical axis: A first lens with positive optical power, whose object side is convex; A second lens with positive optical power, whose object side is convex; A third lens with negative optical power, whose image side is concave; A fourth lens with positive optical power; A fifth lens with negative optical power, whose object side is concave and image side is concave; A sixth lens with positive optical power, whose image side is convex; The number of lenses with optical power in the industrial lens is six; and The industrial lens satisfies: 1.61 ≤ fa / fb ≤ 4.22, where fa is the combined effective focal length of the first lens to the third lens, and fb is the combined effective focal length of the fourth lens to the sixth lens.

2. The industrial lens according to claim 1, wherein The image side of the first lens is convex or concave or flat; The image side of the second lens is convex or concave or flat; The object side of the third lens is convex or concave or flat; The object side of the fourth lens is convex or concave or flat, and the image side is convex; The object side of the sixth lens is convex or concave or flat.

3. The industrial lens according to claim 1, characterized in that The industrial lens includes a diaphragm, and the diaphragm is located between the third lens and the fourth lens.

4. The industrial lens according to claim 1 or 2, characterized in that, The industrial lens satisfies at least one of the following conditional expressions: 1.31 ≤ fa / f ≤ 2.78, 0.59 ≤ fb / f ≤ 0.90, where fa is the combined effective focal length of the first lens to the third lens, fb is the combined effective focal length of the fourth lens to the sixth lens, and f is the total effective focal length of the industrial lens.

5. The industrial lens according to claim 1 or 2, characterized in that, The industrial lens satisfies at least one of the following conditional expressions: -1.01 ≤ f23 / fa ≤ -0.23, -9.55 mm ≤ (f2 + f3) * f23 / (f1 + f2 + f3) ≤ -2.77 mm, 0.53 ≤ ((nd1 + nd3) / nd2) * (f1 + f3) / fa ≤ 1.07, where fa is the combined effective focal length of the first lens to the third lens, f23 is the combined effective focal length of the second lens to the third lens, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, nd1 is the refractive index of the first lens, nd2 is the refractive index of the second lens, and nd3 is the refractive index of the third lens.

6. The industrial lens according to claim 1 or 2, characterized in that, The industrial lens satisfies at least one of the following conditional expressions: 0.62 ≤ (f4 + f5 + f6) / fb ≤ 1.11, -2.26 ≤ (R32 / R51) * (f3 / f5) ≤ -0.13, -1.63 ≤ R5n / f5 ≤ -0.94, 0.36 ≤ TCbn_max / fbn ≤ 1.21, Wherein, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, fb is the combined effective focal length of the fourth lens to the sixth lens, R32 is the curvature radius of the image side surface of the third lens, R51 is the curvature radius of the object side surface of the fifth lens, R5n is the minimum value of the absolute value of the curvature radius of the object side surface or the image side surface of the fifth lens, TCbn_max is the maximum value of the center thickness of any one of the fourth lens, the fifth lens, and the sixth lens, and fbn is the minimum value of the absolute value of the effective focal length of any one of the fourth lens, the fifth lens, and the sixth lens.

7. The industrial lens according to claim 1 or 2, characterized in that The industrial lens satisfies at least one of the following conditional expressions: 1.20 ≤ (f1 + f6) / f ≤ 1.63, 4.61 ≤ (R11 + R21)*(f1 + f2) / |R62*f6| ≤ 9.04, 6.32 mm -1 ≤ (vd4 + vd6) / f6 ≤ 10.05 mm -1 , 0.11 ≤ (TCn_max - TCn_min) / TCn_sum ≤ 0.17, Wherein, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f6 is the effective focal length of the sixth lens, f is the total effective focal length of the industrial lens, R11 is the curvature radius of the object side surface of the first lens, R21 is the curvature radius of the object side surface of the second lens, R62 is the curvature radius of the image side surface of the sixth lens, vd4 is the Abbe number of the fourth lens, vd6 is the Abbe number of the sixth lens, TCn_max is the maximum value of the center thickness of any one of the first lens to the sixth lens, TCn_min is the minimum value of the center thickness of any one of the first lens to the sixth lens, and TCn_sum is the sum of the center thicknesses of the lenses from the first lens to the sixth lens.

8. The industrial lens according to claim 3, characterized in that, The industrial lens satisfies at least one of the following conditional expressions: 10.03 mm ≤ fb*(TC4 + TC5 + TC6) / CTb ≤ 14.15 mm, 1.73 ≤ CTb / CTa ≤ 2.58, Wherein, fb is the combined effective focal length of the fourth lens to the sixth lens, TC4 is the center thickness of the fourth lens, TC5 is the center thickness of the fifth lens, TC6 is the center thickness of the sixth lens, CTa is the center distance from the object side surface of the first lens to the diaphragm surface, and CTb is the center distance from the diaphragm surface to the image side surface of the sixth lens.

9. The industrial lens according to claim 1 or 2, characterized in that, The industrial lens satisfies at least one of the following conditional expressions: 1.78 ≤ fa / fb ≤ 3.84, 1.45 ≤ fa / f ≤ 2.53, 0.65 ≤ fb / f ≤ 0.82, -0.92 ≤ f23 / fa ≤ -0.26, -8.69 mm ≤ (f2 + f3)*f23 / (f1 + f2 + f3) ≤ -3.07 mm, 0.68 ≤ (f4 + f5 + f6) / fb ≤ 0.94, -2.06 ≤ (R32 / R51)*(f3 / f5) ≤ -0.24, -1.44 ≤ R5n / f5 ≤ -1.00, 0.58 ≤ ((nd1 + nd3) / nd2) * (f1 + f3) / fa ≤ 0.98, 1.31 ≤ (f1 + f6) / f ≤ 1.48, 5.11 ≤ (R11 + R21) * (f1 + f2) / |R62 * f6| ≤ 8.23, 0.40 ≤ TCbn_max / fbn ≤ 1.11, 7.03 mm -1 ≤ (vd4 + vd6) / f6 ≤ 9.14 mm -1 , 0.11 ≤ (TCn_max - TCn_min) / TCn_sum ≤ 0.16, Wherein, fa is the combined effective focal length of the first lens to the third lens, fb is the combined effective focal length of the fourth lens to the sixth lens, f is the total effective focal length of the industrial lens, f23 is the combined effective focal length of the second lens to the third lens, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, R11 is the curvature radius of the object side surface of the first lens, R21 is the curvature radius of the object side surface of the second lens, R32 is the curvature radius of the image side surface of the third lens, R51 is the curvature radius of the object side surface of the fifth lens, R62 is the curvature radius of the image side surface of the sixth lens, R5n is the minimum value of the absolute value of the curvature radius of the object side surface or the image side surface of the fifth lens, nd1 is the refractive index of the first lens, nd2 is the refractive index of the second lens, nd3 is the refractive index of the third lens, vd4 is the Abbe number of the fourth lens, vd6 is the Abbe number of the sixth lens, TCbn_max is the maximum value of the center thickness of any one of the fourth lens, the fifth lens and the sixth lens, fbn is the minimum value of the absolute value of the effective focal length of any one of the fourth lens, the fifth lens and the sixth lens, TCn_max is the maximum value of the center thickness of any one of the first lens to the sixth lens, TCn_min is the minimum value of the center thickness of any one of the first lens to the sixth lens, and TCn_sum is the sum of the center thicknesses of the lenses from the first lens to the sixth lens.

10. The industrial lens according to claim 3, characterized in that, The industrial lens satisfies at least one of the following conditional expressions: 11.23 mm ≤ fb * (TC4 + TC5 + TC6) / CTb ≤ 12.87 mm, 1.92 ≤ CTb / CTa ≤ 2.35, Wherein, fb is the combined effective focal length of the fourth lens to the sixth lens, TC4 is the center thickness of the fourth lens, TC5 is the center thickness of the fifth lens, TC6 is the center thickness of the sixth lens, CTa is the center distance from the object side surface of the first lens to the diaphragm surface, and CTb is the center distance from the diaphragm surface to the image side surface of the sixth lens.

Images