A machine vision lens

Abstract

The application discloses a machine vision lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens arranged in sequence along an optical axis from an object plane to an image plane; wherein the first lens is a positive focal length lens, the second lens is a negative focal length lens, the third lens is a negative focal length lens, the fourth lens is a positive focal length lens, the fifth lens is a positive focal length lens, the sixth lens is a negative focal length lens, the seventh lens is a positive focal length lens, the eighth lens is a negative focal length lens, the ninth lens is a negative focal length lens, the tenth lens is a positive focal length lens, the eleventh lens is a positive focal length lens, and the twelfth lens is a negative focal length lens. By reasonably setting the number of lenses and the focal length of the lenses in the machine vision lens, the machine vision lens with clear imaging and small distortion can be realized.

Description

Technical Field

[0001] The present invention relates to the field of optical device technology, and in particular to a machine vision lens. Background Technology

[0002] Machine vision lenses are widely used in manufacturing, quality inspection, logistics, medicine, scientific research and other fields. With the rapid development of industrial automation, machine vision lenses occupy an important position as the "eyes" of automated machines.

[0003] In order to meet more measurement needs, there is a general demand for a lens with a short focal length, short overall length, clear imaging, low distortion, and bright overall image. Summary of the Invention

[0004] This invention provides a machine vision lens that achieves the design of a low-cost machine vision lens that can meet both imaging requirements and low distortion.

[0005] This invention provides a machine vision lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, and a twelfth lens arranged sequentially along the optical axis from the object plane to the image plane; Wherein, the first lens is a positive power lens, the second lens is a negative power lens, the third lens is a negative power lens, the fourth lens is a positive power lens, the fifth lens is a positive power lens, the sixth lens is a negative power lens, the seventh lens is a positive power lens, the eighth lens is a negative power lens, the ninth lens is a negative power lens, the tenth lens is a positive power lens, the eleventh lens is a positive power lens, and the twelfth lens is a negative power lens.

[0006] Optionally, the fifth lens and the sixth lens are cemented together to form a first cemented lens.

[0007] Optionally, the seventh lens and the eighth lens form a second cemented lens; The seventh lens has a refractive index of Nd7 and an Abbe number of Vd7; the eighth lens has a refractive index of Nd8 and an Abbe number of Vd8. Among them, 0.17≤|Nd7-Nd8|≤0.63, 20.3≤|Vd7-Vd8|≤48.

[0008] Optionally, the ninth lens and the tenth lens form a third cemented lens.

[0009] Optionally, the eleventh lens and the twelfth lens form a fourth cemented lens; The eleventh lens has a refractive index of Nd11 and an Abbe number of Vd11; the twelfth lens has a refractive index of Nd12 and an Abbe number of Vd12. Among them, 0.2≤|Nd11-Nd12|≤0.6, 46≤|Vd11-Vd12|.

[0010] Optionally, the air gap on the optical axis between the image side of the third lens and the object side of the fourth lens is T34, and the total optical length of the machine vision lens system is TTL. Among them, 8.90≤TTL / T34≤17.1.

[0011] Optionally, the air gap on the optical axis between the image side of the eighth lens and the object side of the ninth lens is T89, the air gap on the optical axis between the image side of the ninth lens and the object side of the tenth lens is T910, the air gap on the optical axis between the image side of the tenth lens and the object side of the eleventh lens is T1011, the back focal length of the machine vision lens is BFL, and the total optical length of the system of the machine vision lens is TTL. Among them, 5.82≤TTL / (T89+T910+T1011+BFL) ≤7.40.

[0012] Optionally, the first lens includes a first object-side surface near the object plane and a first image-side surface near the image plane; the first object-side surface is convex, and the first image-side surface is concave; and the first lens is a meniscus lens. The second lens includes a second object-side surface near the object plane and a second image-side surface near the image plane; the second object-side surface is convex, and the second image-side surface is concave. The third lens includes a third object-side surface near the object plane and a third image-side surface near the image plane; the third object-side surface is a convex surface, a concave surface, or a plane, and the third image-side surface is a concave surface; The fourth lens includes a fourth object-side surface near the object plane and a fourth image-side surface near the image plane; the fourth object-side surface is a convex surface, a concave surface, or a plane, and the fourth image-side surface is a convex surface; The fifth lens includes a fifth object-side surface near the object plane and a fifth image-side surface near the image plane; the fifth object-side surface is concave and the fifth image-side surface is convex. The sixth lens includes a sixth object-side surface near the object plane and a sixth image-side surface near the image plane; the sixth object-side surface is concave and the sixth image-side surface is convex. The seventh lens includes a seventh object-side surface near the object plane and a seventh image-side surface near the image plane; the seventh object-side surface is concave and the seventh image-side surface is convex; and the seventh lens is a meniscus lens. The eighth lens includes an eighth object-side surface near the object plane and an eighth image-side surface near the image plane; the eighth object-side surface is concave and the eighth image-side surface is convex; and the eighth lens is a meniscus lens. The ninth lens includes a ninth object-side surface near the object plane and a ninth image-side surface near the image plane; the ninth object-side surface is convex, and the ninth image-side surface is concave; and the ninth lens is a meniscus lens. The tenth lens includes a tenth object-side surface near the object plane and a tenth image-side surface near the image plane; the tenth object-side surface is convex and the tenth image-side surface is convex. The eleventh lens includes an eleventh object-side surface near the object plane and an eleventh image-side surface near the image plane; the eleventh object-side surface is convex, and the eleventh image-side surface is convex. The twelfth lens includes a twelfth object-side surface near the object plane and a twelfth image-side surface near the image plane; the twelfth object-side surface is concave and the twelfth image-side surface is convex; and the second lens is a meniscus lens.

[0013] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens are all glass spherical lenses.

[0014] The machine vision lens provided in this invention comprises twelve lenses, with the optical powers of the first to twelfth lenses being positive, negative, negative, positive, positive, negative, positive, negative, negative, positive, positive, positive, and negative, respectively. By rationally setting the combination of optical powers of the lenses in the lens, more light can enter the optical system, thereby effectively increasing the field of view of the machine vision lens and reducing distortion, thus improving the imaging effect of the machine vision lens. Ultimately, this achieves the design of a low-cost machine vision lens that can balance imaging requirements and low distortion.

[0015] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a machine vision lens at the main working distance according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of a machine vision lens at the closest working object distance according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the structure of a machine vision lens at the farthest working object distance according to Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the main working object distance, provided in Embodiment 1 of the present invention. Figure 5 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the main working object distance, provided in Embodiment 1 of the present invention. Figure 8 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the closest working object distance, provided in Embodiment 1 of the present invention; Figure 9 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the farthest working object distance, provided in Embodiment 1 of the present invention. Figure 10 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the main working object distance, provided in Embodiment 1 of the present invention. Figure 11 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 1 of the present invention; Figure 12 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 1 of the present invention. Figure 13 This is a schematic diagram of the structure of a machine vision lens at the main working distance according to Embodiment 2 of the present invention; Figure 14This is a schematic diagram of the structure of a machine vision lens at the closest working object distance according to Embodiment 2 of the present invention; Figure 15 This is a schematic diagram of the structure of a machine vision lens at the farthest working object distance according to Embodiment 2 of the present invention; Figure 16 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the main working distance, provided in Embodiment 2 of the present invention. Figure 17 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 2 of the present invention. Figure 18 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 2 of the present invention; Figure 19 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the main working object distance, provided in Embodiment 2 of the present invention. Figure 20 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the closest working object distance, provided in Embodiment 2 of the present invention; Figure 21 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the farthest working object distance, provided in Embodiment 2 of the present invention. Figure 22 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the main working object distance, provided in Embodiment 2 of the present invention. Figure 23 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 2 of the present invention; Figure 24 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 2 of the present invention. Figure 25 This is a schematic diagram of the structure of a machine vision lens at the main working distance according to Embodiment 3 of the present invention; Figure 26 This is a schematic diagram of the structure of a machine vision lens at the closest working object distance provided in Embodiment 3 of the present invention; Figure 27 This is a schematic diagram of the structure of a machine vision lens at the farthest working object distance provided in Embodiment 3 of the present invention; Figure 28 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the main working distance, provided in Embodiment 3 of the present invention. Figure 29 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 3 of the present invention; Figure 30This is a schematic diagram of the spherical aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 3 of the present invention; Figure 31 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the main working object distance, provided in Embodiment 3 of the present invention. Figure 32 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the closest working object distance, provided in Embodiment 3 of the present invention; Figure 33 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the farthest working object distance, provided in Embodiment 3 of the present invention. Figure 34 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the main working object distance, provided in Embodiment 3 of the present invention; Figure 35 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 3 of the present invention; Figure 36 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 3 of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0019] Example 1 Figure 1 This is a schematic diagram of the structure of a machine vision lens at the main working distance according to Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the structure of a machine vision lens at the closest working object distance according to Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the structure of a machine vision lens at its farthest working object distance, according to Embodiment 1 of the present invention. Figures 1 to 3 The working object distances differ, specifically in the distance from the image side of the third lens to the object side of the fourth lens. (Combined with...) Figure 1 , Figure 2 and Figure 3As shown, the machine vision lens provided in Embodiment 1 of the present invention includes a first lens 111, a second lens 112, a third lens 113, a fourth lens 114, a fifth lens 115, a sixth lens 116, a seventh lens 117, an eighth lens 118, a ninth lens 119, a tenth lens 120, an eleventh lens 121, and a twelfth lens 122 arranged sequentially along the optical axis from the object plane to the image plane. The first lens 111 is a positive power lens, the second lens 112 is a negative power lens, the third lens 113 is a negative power lens, the fourth lens 114 is a positive power lens, the fifth lens 115 is a positive power lens, the sixth lens 116 is a negative power lens, the seventh lens 117 is a positive power lens, the eighth lens 118 is a negative power lens, the ninth lens 119 is a negative power lens, the tenth lens 120 is a positive power lens, the eleventh lens 121 is a positive power lens, and the twelfth lens 122 is a negative power lens.

[0020] Optical power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam; it characterizes the ability of an optical system to deflect light rays. The larger the absolute value of the optical power, the stronger the bending ability of light rays; the smaller the absolute value, the weaker the bending ability. When the optical power is positive, the refraction of light rays is converging; when the optical power is negative, the refraction of light rays is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system formed by multiple lenses (i.e., a lens group).

[0021] Specifically, the first lens 111 is a positive power lens, the second lens 112 is a negative power lens, and the third lens 113 is a negative power lens. This combination of positive-negative-negative power lenses effectively deflects large-angle incident light, ensuring more light enters the optical system and thus effectively increasing the field of view of the machine vision lens, guaranteeing the optical system has wide-angle characteristics. Furthermore, the fourth lens 114, the fifth lens 115, and the sixth lens 116 are all positive power lenses. This combination of positive-positive-negative power lenses converges the relatively divergent light entering from the first lens 111, second lens 112, and third lens 113, allowing the light to better enter the subsequent optical system.

[0022] Furthermore, the fourth lens 114 is set as a positive optical power lens and the ninth lens 119 is set as a negative optical power lens. The combination of positive optical power and negative optical power formed by the fourth lens 114 and the ninth lens 119 can reduce imaging distortion and improve imaging effect.

[0023] Furthermore, the first lens 111, the second lens 112, the third lens 113, the fourth lens 114, the fifth lens 115, and the sixth lens 116 form a combination of positive optical power-negative optical power-negative optical power-positive optical power-positive optical power-negative optical power, and the seventh lens 117, the eighth lens 118, the ninth lens 119, the tenth lens 120, the eleventh lens 121, and the twelfth lens 122 form a combination of positive optical power-negative optical power-negative optical power-positive optical power-positive optical power-negative optical power. That is, the first lens 111 to the sixth lens 116 and the seventh lens 117 to the twelfth lens 122 form an approximately symmetrical optical system, and the first lens 111 to the twelfth lens 122 form a double Gaussian optical system. This is beneficial for reducing imaging distortion and improving imaging effect.

[0024] In summary, the machine vision lens provided by the embodiments of the present invention facilitates the entry of more light into the optical system, thereby effectively increasing the field of view of the machine vision lens, reducing lens distortion, improving the imaging effect of the machine vision lens, and ultimately realizing the design of a low-cost machine vision lens that can meet imaging requirements and reduce distortion.

[0025] Continue to refer to Figures 1-3 As shown, based on the above embodiment, the fifth lens 115 and the sixth lens 116 are cemented together to form a first cemented lens.

[0026] The fifth lens 115 and the sixth lens 116 are cemented together to form a cemented lens, which can be understood as the image-side surface of the fifth lens 115 being cemented to the object-side surface of the sixth lens 116. Cemented lenses can be used to minimize or eliminate chromatic aberration. Using cemented lenses in fixed-focus lenses can improve image quality and reduce light energy reflection loss, thereby enhancing the sharpness of the lens image. Furthermore, the use of cemented lenses can simplify the assembly process in lens manufacturing, improving equipment efficiency. For example, the cemented lens composed of the fifth lens 115 and the sixth lens 116 can help eliminate the effects of chromatic aberration and reduce tolerance sensitivity; at the same time, the cemented lens can also balance the overall chromatic aberration of the optical system. The cementation of the lenses eliminates the air gap between the two lenses, making the overall optical system compact and meeting the requirements of system miniaturization. Moreover, the cementation of the lenses reduces tolerance sensitivity issues such as tilting / eccentricity that occur during the assembly of lens units. Furthermore, the fifth lens 115 and the sixth lens 116 can be supported by a gasket or glued together. This utility model does not limit the specific arrangement of the glued lenses.

[0027] Continue to refer to Figures 1-3As shown, based on the above embodiment, the seventh lens 117 and the eighth lens 118 form a second cemented lens; the refractive index of the seventh lens 117 is Nd7 and the Abbe number is Vd7; the refractive index of the eighth lens 118 is Nd8 and the Abbe number is Vd8; wherein, 0.17≤|Nd7-Nd8|≤0.63, 20.3≤|Vd7-Vd8|≤48.

[0028] Specifically, the seventh lens 117 and the eighth lens 118 are cemented together to form a cemented lens, which can be understood as the image-side surface of the seventh lens 117 being cemented to the object-side surface of the eighth lens 118. Cemented lenses can be used to minimize or eliminate chromatic aberration. Using cemented lenses in fixed-focus lenses can improve image quality and reduce light energy reflection loss, thereby enhancing the sharpness of the lens image. Furthermore, the use of cemented lenses can simplify the assembly process in lens manufacturing, improving equipment efficiency. For example, the cemented lens composed of the seventh lens 117 and the eighth lens 118 can help eliminate the effects of chromatic aberration and reduce tolerance sensitivity; at the same time, the cemented lens can also balance the overall chromatic aberration of the optical system. The cementation of the lenses eliminates the air gap between the two lenses, making the overall optical system compact and meeting the requirements for system miniaturization. Moreover, the cementation of the lenses reduces tolerance sensitivity issues such as tilting / eccentricity that occur during the assembly of lens units. Furthermore, the seventh lens 117 and the eighth lens 118 can be supported by a gasket or glued together. This utility model does not limit the specific arrangement of the glued lenses.

[0029] Furthermore, the refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium, mainly used to describe a material's ability to refract light; different materials have different refractive indices. The Abbe number is an index used to represent the dispersion ability of a transparent medium; the more severe the dispersion, the smaller the Abbe number; conversely, the less severe the dispersion, the larger the Abbe number. By setting the refractive index Nd7 of the seventh lens 117 and the refractive index Nd8 of the eighth lens 118 to satisfy 0.17 ≤ |Nd7 - Nd8| ≤ 0.63, and the Abbe number Vd7 of the seventh lens 117 and the Abbe number Vd8 of the eighth lens 118 to satisfy 20.3 ≤ |Vd7 - Vd8| ≤ 48, the parameter control in the second cemented lens ensures the refraction effect of the second cemented lens and the control effect of image chromatic aberration.

[0030] Based on the above embodiment, the ninth lens 119 and the tenth lens 120 form a third cemented lens.

[0031] Specifically, the ninth lens 119 and the tenth lens 120 are cemented together to form a cemented lens, which can be understood as the image-side surface of the ninth lens 119 being cemented to the object-side surface of the tenth lens 120. Cemented lenses can be used to minimize or eliminate chromatic aberration. Using cemented lenses in fixed-focus lenses can improve image quality and reduce light energy reflection loss, thereby enhancing the sharpness of the lens image. Furthermore, the use of cemented lenses can simplify the assembly process in lens manufacturing, improving equipment efficiency. For example, the cemented lens composed of the ninth lens 119 and the tenth lens 120 can help eliminate the effects of chromatic aberration and reduce tolerance sensitivity; at the same time, the cemented lens can also balance the overall chromatic aberration of the optical system. The cementation of the lenses eliminates the air gap between the two lenses, making the overall optical system compact and meeting the requirements of system miniaturization. Moreover, the cementation of the lenses reduces tolerance sensitivity issues such as tilting / eccentricity that occur during the assembly of lens units. Furthermore, since the ninth lens 119 is a negative power lens and the tenth lens 120 is a positive power lens, the cemented lens formed by the two lenses with negative light penetration and positive power can further reduce axial chromatic aberration and improve the imaging effect of the optical system. Furthermore, the ninth lens 119 and the tenth lens 120 can be supported by a gasket or bonded together with adhesive; this invention does not limit the specific arrangement of the cemented lens.

[0032] Continue to refer to Figures 1-3 As shown, based on the above embodiment, the eleventh lens 121 and the twelfth lens 122 form a fourth cemented lens; the refractive index of the eleventh lens is Nd11 and the Abbe number is Vd11; the refractive index of the twelfth lens is Nd12 and the Abbe number is Vd12; wherein, 0.2≤|Nd11-Nd12|≤0.6, 46≤|Vd11-Vd12|.

[0033] Specifically, the eleventh lens 121 and the twelfth lens 122 are cemented together to form a cemented lens, which can be understood as the image-side surface of the eleventh lens 121 being cemented to the object-side surface of the twelfth lens 122. Cemented lenses can be used to minimize or eliminate chromatic aberration. Using cemented lenses in fixed-focus lenses can improve image quality and reduce light energy reflection loss, thereby enhancing the sharpness of the lens image. Furthermore, the use of cemented lenses can simplify the assembly process in lens manufacturing, improving equipment efficiency. For example, the cemented lens composed of the eleventh lens 121 and the twelfth lens 122 can help eliminate the effects of chromatic aberration and reduce tolerance sensitivity; at the same time, the cemented lens can also balance the overall chromatic aberration of the optical system. The cementation of the lenses eliminates the air gap between the two lenses, making the overall optical system compact and meeting the requirements of system miniaturization. Moreover, the cementation of the lenses reduces tolerance sensitivity issues such as tilting / eccentricity that occur during the assembly of lens units. Furthermore, the eleventh lens 121 and the twelfth lens 122 can be supported by a gasket or glued together. This utility model does not limit the specific arrangement of the glued lenses.

[0034] Furthermore, by setting the refractive index Nd11 of the eleventh lens 121 and the refractive index Nd12 of the twelfth lens 122 to satisfy 0.2≤|Nd11-Nd12|≤0.6, and the Abbe number Vd11 of the eleventh lens 121 and the Abbe number Vd12 of the twelfth lens 122 to satisfy 46≤|Vd11-Vd12|, the parameter control in the fourth cemented lens ensures the refraction effect of the fourth cemented lens on light and the control effect of imaging chromatic aberration.

[0035] Based on the above embodiment, the air gap on the optical axis between the image side of the third lens 113 and the object side of the fourth lens 114 is T34, and the total optical length of the machine vision lens system is TTL; wherein, 8.90≤TTL / T34≤17.1. By adjusting the air gap T34 on the optical axis between the image side of the third lens 113 and the object side of the fourth lens 114, it is easier to determine the optimal imaging position and improve the imaging quality.

[0036] Based on the above embodiment, the air gap on the optical axis between the image side of the eighth lens 118 and the object side of the ninth lens 119 is T89, the air gap on the optical axis between the image side of the ninth lens 119 and the object side of the tenth lens 120 is T910, and the air gap on the optical axis between the image side of the tenth lens 120 and the object side of the eleventh lens 121 is T1011. The back focal length of the machine vision lens is BFL, and the total optical length of the machine vision lens system is TTL; wherein, 5.82≤TTL / (T89+T910+T1011+BFL) ≤7.40. This configuration allows for a relatively small focal length of the entire optical system, for example, around 4mm, achieving a short-focal-length machine vision lens that meets the short-focal-length requirements of machine vision lenses.

[0037] Based on the above embodiments, the first lens 111 includes a first object-side surface near the object plane and a first image-side surface near the image plane; the first object-side surface is convex, and the first image-side surface is concave; and the first lens is a meniscus lens; the second lens 112 includes a second object-side surface near the object plane and a second image-side surface near the image plane; the second object-side surface is convex, and the second image-side surface is concave; the third lens 113 includes a third object-side surface near the object plane and a third image-side surface near the image plane; the third object-side surface is convex, concave, or flat, and the third image-side surface is concave. The fourth lens 114 includes a fourth object-side surface near the object plane and a fourth image-side surface near the image plane; the fourth object-side surface is convex, concave, or flat, and the fourth image-side surface is convex; the fifth lens 115 includes a fifth object-side surface near the object plane and a fifth image-side surface near the image plane; the fifth object-side surface is concave, and the fifth image-side surface is convex; the sixth lens 116 includes a sixth object-side surface near the object plane and a sixth image-side surface near the image plane; the sixth object-side surface is concave, and the sixth image-side surface is convex; the seventh lens 117 includes a fourth object-side surface near the object plane and a sixth image-side surface near the image plane; the sixth object-side surface is concave, and the sixth image-side surface is convex; the seventh lens 117 includes a fourth object-side surface near the object plane and a sixth image-side surface near the image plane. The seventh object-side surface on one side of the object plane and the seventh image-side surface on the side closer to the image plane; the seventh object-side surface is concave, and the seventh image-side surface is convex; and the seventh lens 117 is a meniscus lens; the eighth lens 118 includes an eighth object-side surface on the side closer to the object plane and an eighth image-side surface on the side closer to the image plane; the eighth object-side surface is concave, and the eighth image-side surface is convex; and the eighth lens is a meniscus lens; the ninth lens 119 includes a ninth object-side surface on the side closer to the object plane and a ninth image-side surface on the side closer to the image plane; the ninth object-side surface is convex, and the ninth image-side surface is concave; and the ninth lens is a meniscus lens. The tenth lens 120 includes a tenth object-side surface near the object plane and a tenth image-side surface near the image plane; the tenth object-side surface is convex and the tenth image-side surface is convex. The eleventh lens 121 includes an eleventh object-side surface near the object plane and an eleventh image-side surface near the image plane; the eleventh object-side surface is convex and the eleventh image-side surface is convex. The twelfth lens 122 includes a twelfth object-side surface near the object plane and a twelfth image-side surface near the image plane; the twelfth object-side surface is concave and the twelfth image-side surface is convex; and the twelfth lens is a meniscus lens.

[0038] Specifically, the first object-side surface of the first lens 111 is convex, and the first image-side surface is concave. That is, the object-side surface of the first lens 111 convexes towards the object plane, and the image-side surface is concave towards the image plane; in other words, the first lens 111 is a lens with a convex-concave structure. Furthermore, the first lens 111 is a meniscus lens. This structure is beneficial for light collection, ensuring a large field of view for the machine vision lens and achieving a wide-angle characteristic. Similarly, the second object-side surface of the second lens 112 is convex, and the second image-side surface is concave. That is, the object-side surface of the second lens 112 convexes towards the object plane, and the image-side surface is concave towards the image plane; in other words, the second lens 112 is a lens with a convex-concave structure. Furthermore, the second lens 112 is a meniscus lens. This structure is beneficial for light collection, ensuring a large field of view for the machine vision lens and achieving a wide-angle characteristic. The third object-side surface of the third lens 113 is convex, concave, or flat, while the third image-side surface is concave. That is, the object-side surface of the third lens 113 convexes, concaves, or remains flat towards the object surface, while the image-side surface is concave towards the image surface. In other words, the third lens 113 is a convex-concave lens, a biconcave lens, or a plano-concave lens. The fourth object-side surface of the fourth lens 114 is convex, concave, or flat, while the fourth image-side surface is convex. That is, the object-side surface of the fourth lens 114 convexes, concaves, or remains flat towards the object surface, while the image-side surface convex towards the image surface. In other words, the fourth lens 114 is a biconvex lens, a concave-convex lens, or a plano-convex lens. The fifth object-side surface of the fifth lens 115 is concave, while the fifth image-side surface is convex. That is, the object-side surface of the fifth lens 115 is concave towards the object surface, while the image-side surface convex towards the image surface. In other words, the fifth lens 115 is a concave-convex lens. The sixth object-side surface of the sixth lens 116 is concave, and the sixth image-side surface is convex. That is, the object-side surface of the sixth lens 116 is concave towards the object plane, and the image-side surface is convex towards the image plane; therefore, the sixth lens 116 is a concave-convex lens. The seventh object-side surface of the seventh lens 117 is concave, and the seventh image-side surface is convex. That is, the object-side surface of the seventh lens 117 is concave towards the object plane, and the image-side surface is convex towards the image plane; therefore, the seventh lens 117 is a lens with a concave-convex structure. Furthermore, the seventh lens 117 is a meniscus lens, a structure that facilitates the coupling of more light rays into the seventh lens 117. The eighth object-side surface of the eighth lens 118 is concave, and the eighth image-side surface is convex. That is, the object-side surface of the eighth lens 118 is concave towards the object plane, and the image-side surface is convex towards the image plane; therefore, the eighth lens 118 is a lens with a concave-convex structure. Furthermore, the eighth lens 118 is a meniscus lens, a structure that facilitates the coupling of more light rays into the eighth lens 118. The ninth object-side surface of the ninth lens 119 is convex, and the ninth image-side surface is concave. That is, the object-side surface of the ninth lens 119 convexes towards the object plane, and the image-side surface is concave towards the image plane. In other words, the ninth lens 119 is a lens with a convex-concave structure. Furthermore, the ninth lens 119 is a meniscus lens. This structure facilitates the coupling of more light rays into the ninth lens 119.The tenth object-side surface of the tenth lens 120 is convex, and the tenth image-side surface is also convex. That is, the object-side surface of the tenth lens 120 convexes towards the object plane, and the image-side surface convexes towards the image plane; thus, the tenth lens 120 is a biconvex lens. The eleventh lens 121 also has an eleventh object-side surface and an eleventh image-side surface; that is, the object-side surface of the eleventh lens 121 convexes towards the object plane, and the image-side surface convexes towards the image plane; thus, the eleventh lens 121 is a biconvex lens. The twelfth lens 122 has a twelfth object-side surface and a twelfth image-side surface convex. That is, the object-side surface of the twelfth lens 122 is concave towards the object plane, and the image-side surface convex towards the image plane; thus, the twelfth lens 122 is a concave-convex lens. Furthermore, the twelfth lens 122 is a meniscus lens, which facilitates the coupling of more light rays into the twelfth lens 122. The shapes of the various lenses are arranged in this manner to facilitate the correction of monochromatic aberrations, while also ensuring a compact overall machine vision lens structure and high integration.

[0039] Based on the above embodiments, the first lens 111, the second lens 112, the third lens 113, the fourth lens 114, the fifth lens 115, the sixth lens 116, the seventh lens 117, the eighth lens 118, the ninth lens 119, the tenth lens 120, the eleventh lens 121 and the twelfth lens 122 are all glass spherical lenses.

[0040] Specifically, a spherical lens is characterized by a constant curvature from its center to its periphery, ensuring a simple lens setup. Therefore, the first lens 111 to the twelfth lens 122 are all spherical lenses, and spherical lenses simplify the optical system setup. Furthermore, the spherical lens setup can balance high and low temperatures. When the ambient temperature of the machine vision lens varies significantly, it helps maintain the focal length stability of the machine vision lens, for example, ensuring stable optical performance between -40℃ and 85℃. Moreover, the first lens 111 to the twelfth lens 122 can be glass spherical lenses.

[0041] Based on the above embodiments, the machine vision lens also includes an aperture stop 123 and a filter 124; the aperture stop 123 is disposed in the optical path between the sixth lens 116 and the seventh lens 117; the filter 124 is disposed in the optical path between the twelfth lens 122 and the image plane.

[0042] Specifically, by setting the aperture stop 123, the propagation direction of the light beam can be adjusted, which is beneficial to improving image quality. Furthermore, in this machine vision lens, the aperture stop 123 can be located in the optical path between the sixth lens 116 and the seventh lens 117. Positioning the aperture stop 123 in the middle of the machine vision lens ensures that the front and rear apertures of the lens are minimized. Further, the filter 124 is positioned in the optical path between the twelfth lens 122 and the image plane. The filter 124 can filter out stray spectra, ensuring image quality. Furthermore, the machine vision lens may also include a flat glass plate, which serves to protect the lens and the image sensor.

[0043] As a feasible implementation method, the parameters of each lens in the machine vision lens will be explained next.

[0044] Table 1. Optical design values ​​for the machine vision lens in Example 1 Table 2. T34 Interval Distances Corresponding to Different Object Distances for Machine Vision Lenses Table 3 Design values ​​for a machine vision lens In Table 3 above, the surface numbers are assigned according to the surface order of each lens. "S1" represents the object-side surface of the first lens, "S2" represents the image-side surface of the first lens, and so on. "STO" represents the aperture stop of the lens. The radius of curvature represents the curvature of the lens surface; a positive value indicates that the surface bends towards the object plane, and a negative value indicates that the surface bends towards the image plane. "Infinite" indicates that the surface is flat and the radius of curvature is infinite. Thickness represents the central axial distance between the current surface and the next surface. Nd represents the refractive index, which represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current position is air with a refractive index of 1. Vd represents the Abbe constant, which represents the dispersion characteristics of the material between the current surface and the next surface. A blank space indicates that the current position is air. S23 represents the total thickness of the protective glass and the filter. The specific parameters of the machine vision lens corresponding to the above embodiment one are as follows: Focal length f: 3.920mm; Aperture: F#2.8; Total optical length (TTL): 55.9mm; Optimal working distance: 300mm.

[0045] Furthermore, Figure 4This is a schematic diagram of the spherical aberration curve of a machine vision lens at the main working object distance according to Embodiment 1 of the present invention. The vertical direction represents the normalized aperture, 0 indicates that it is on the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focal point, in millimeters (mm). Different linear curves in the figure represent different wavelengths of system imaging (e.g., 0.449μm, 0.510μm, 0.540μm, 0.570μm, 0.600μm, 0.640μm, and 0.680μm), which are determined by... Figure 4 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0046] Figure 5 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the closest object distance, provided in Embodiment 1 of the present invention. Figure 5 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0047] Figure 6 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 1 of the present invention. Figure 6 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0048] Figure 7 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the main working object distance, provided in Embodiment 1 of the present invention. In the coordinate system on the left side of the figure, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc distortion; Figure 7 It can be seen that the lens provided in this embodiment effectively controls the field curvature from light with wavelengths from 436nm to 656nm, meaning that during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 7 As can be seen, the imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the lens distortion has been well corrected and the difference between the image and the actual object is small.

[0049] Figure 8 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the closest working object distance, provided in Embodiment 1 of the present invention. Figure 8 It can be seen that the lens provided in this embodiment effectively controls the field curvature of light from wavelength 436nm to 656nm. That is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small. The imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the distortion of the lens has been well corrected and the difference between the image and the actual object is small.

[0050] Figure 9 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the farthest working object distance, provided in Embodiment 1 of the present invention. Figure 9 It can be seen that the lens provided in this embodiment effectively controls the field curvature of light from wavelength 436nm to 656nm. That is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small. The imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the distortion of the lens has been well corrected and the difference between the image and the actual object is small.

[0051] Figure 10 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the primary working object distance, provided in Embodiment 1 of the present invention. The vertical direction represents the image height, in mm; the horizontal direction represents the offset of different wavelengths from the optical axis at the image plane after passing through the system, in micrometers (μm). Different linear curves in the figure represent different wavelengths of the system imaging; the curves in the vertical direction on both sides of the figure are Airy disks, formed by... Figure 10 It can be seen that most of the wavelengths in the 450nm~640nm range remain within the Airy disk, indicating that the lens has good control over chromatic aberration at each wavelength, which can meet the application requirements of a wide spectrum.

[0052] Figure 11 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 1 of the present invention. Figure 11 It can be seen that most of the wavelengths in the 450nm~640nm range remain within the Airy disk, indicating that the lens has good control over chromatic aberration at each wavelength, which can meet the application requirements of a wide spectrum.

[0053] Figure 12 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 1 of the present invention. Figure 12 It can be seen that most of the wavelengths in the 450nm~640nm range remain within the Airy disk, indicating that the lens has good control over chromatic aberration at each wavelength, which can meet the application requirements of a wide spectrum.

[0054] In summary, the machine vision lens provided by the embodiments of the present invention, by reasonably setting parameters such as the optical power, surface shape, Abbe number, refractive index, total optical length, and lens type of different lenses, ultimately achieves the design of a low-cost machine vision lens that can balance imaging requirements and small distortion. The machine vision lens has a maximum aperture of 2.8, a total optical length of 55mm, and can be matched with a maximum 1 / 1.8″ sensor chip. Its overall performance meets the requirements of the sensor used.

[0055] Example 2 Figure 13 This is a schematic diagram of the structure of a machine vision lens at the main working object distance according to Embodiment 2 of the present invention. Figure 14 This is a schematic diagram of the structure of a machine vision lens at the closest working object distance according to Embodiment 2 of the present invention. Figure 15 This is a schematic diagram of the structure of a machine vision lens at its farthest working object distance, provided in Embodiment 2 of the present invention. Figures 13 to 15 The working object distances differ, specifically in the distance from the image side of the third lens to the object side of the fourth lens. (Combined with...) Figure 13 , Figure 14 and Figure 15 As shown, the machine vision lens provided in Embodiment 2 of the present invention includes a first lens 111, a second lens 112, a third lens 113, a fourth lens 114, a fifth lens 115, a sixth lens 116, a seventh lens 117, an eighth lens 118, a ninth lens 119, a tenth lens 120, an eleventh lens 121, and a twelfth lens 122 arranged sequentially along the optical axis from the object plane to the image plane. The first lens 111 is a positive power lens, the second lens 112 is a negative power lens, the third lens 113 is a negative power lens, the fourth lens 114 is a positive power lens, the fifth lens 115 is a positive power lens, the sixth lens 116 is a negative power lens, the seventh lens 117 is a positive power lens, the eighth lens 118 is a negative power lens, the ninth lens 119 is a negative power lens, the tenth lens 120 is a positive power lens, the eleventh lens 121 is a positive power lens, and the twelfth lens 122 is a negative power lens.

[0056] The lens setup is the same as in Embodiment 3, and will not be repeated here.

[0057] As another feasible implementation method, the specific parameters of the machine vision lens are explained below.

[0058] Table 4. Optical design values ​​for the machine vision lens in Example 2. Table 5. T34 spacing distances corresponding to different object distances for machine vision lenses. Table 6 Design values ​​for a machine vision lens In Table 6 above, the surface numbers are assigned according to the surface order of each lens. "S1" represents the object-side surface of the first lens, "S2" represents the image-side surface of the first lens, and so on. "STO" represents the aperture stop of the lens. The radius of curvature represents the curvature of the lens surface; a positive value indicates that the surface bends towards the object plane, and a negative value indicates that the surface bends towards the image plane. "Infinite" indicates that the surface is flat and the radius of curvature is infinite. Thickness represents the central axial distance between the current surface and the next surface. nd represents the refractive index, which represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current location is air with a refractive index of 1. vd represents the Abbe constant, which represents the dispersion characteristics of the material between the current surface and the next surface. A blank space indicates that the current location is air. S23 represents the total thickness of the protective glass and the filter.

[0059] The specific parameters of the machine vision lens corresponding to the above embodiment two are as follows: Focal length f: 4.208mm; Aperture: F#2.8; Total optical length (TTL): 55.9mm; Optimal working distance: 300mm.

[0060] Furthermore, Figure 16 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the main working object distance, provided in Embodiment 2 of the present invention. The vertical direction represents the normalized aperture, 0 indicates on the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focal point, in millimeters (mm). Different linear curves in the figure represent different wavelengths of system imaging (e.g., 0.449μm, 0.510μm, 0.540μm, 0.570μm, 0.600μm, 0.640μm, and 0.680μm), which are determined by... Figure 16 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0061] Figure 17 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 2 of the present invention. Figure 17 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0062] Figure 18 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 2 of the present invention. Figure 18 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0063] Figure 19 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the main working object distance, provided in Embodiment 2 of the present invention. In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc distortion; Figure 19 It can be seen that the lens provided in this embodiment effectively controls the field curvature from light with wavelengths from 436nm to 656nm, meaning that during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 19 As can be seen, the imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the lens distortion has been well corrected and the difference between the image and the actual object is small.

[0064] Figure 20 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the closest working object distance, provided in Embodiment 2 of the present invention. Figure 20 It can be seen that the lens provided in this embodiment effectively controls the field curvature of light from wavelength 436nm to 656nm. That is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small. The imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the distortion of the lens has been well corrected and the difference between the image and the actual object is small.

[0065] Figure 21 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the farthest working object distance, provided in Embodiment 2 of the present invention. Figure 21 It can be seen that the lens provided in this embodiment effectively controls the field curvature of light from wavelength 436nm to 656nm. That is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small. The imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the distortion of the lens has been well corrected and the difference between the image and the actual object is small.

[0066] Figure 22This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the main working object distance according to Embodiment 2 of the present invention. The vertical direction represents the image height in mm; the horizontal direction represents the offset of different wavelengths from the optical axis at the image plane after passing through the system in micrometers (μm). Different linear curves in the figure represent different wavelengths of the system imaging; the curves in the vertical direction on both sides of the figure are Airy disks. Figure 8 It can be seen that the transverse chromatic aberration of different wavelengths is mostly kept within the Airy disk, indicating that the lens has good control over chromatic aberration at various wavelengths and can meet the application requirements of a wide spectrum.

[0067] Figure 23 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 2 of the present invention. Figure 23 It can be seen that most of the wavelengths in the 450nm~640nm range remain within the Airy disk, indicating that the lens has good control over chromatic aberration at each wavelength, which can meet the application requirements of a wide spectrum.

[0068] Figure 24 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 2 of the present invention. Figure 24 It can be seen that most of the wavelengths in the 450nm~640nm range remain within the Airy disk, indicating that the lens has good control over chromatic aberration at each wavelength, which can meet the application requirements of a wide spectrum.

[0069] In summary, the machine vision lens provided by the embodiments of the present invention, by reasonably setting parameters such as the optical power, surface shape, Abbe number, refractive index, total optical length, and lens type of different lenses, ultimately achieves the design of a low-cost machine vision lens that can balance imaging requirements and small distortion. The machine vision lens has a maximum aperture of 2.8, a total optical length of 55mm, and can be matched with a maximum 1 / 1.8″ sensor chip. Its overall performance meets the requirements of the sensor used.

[0070] Example 3 Figure 25 This is a schematic diagram of the structure of a machine vision lens at the main working distance according to Embodiment 3 of the present invention. Figure 26 This is a schematic diagram of the structure of a machine vision lens at the closest working object distance according to Embodiment 3 of the present invention. Figure 27 This is a schematic diagram of the structure of a machine vision lens at its farthest working object distance, provided in Embodiment 3 of the present invention. Figures 25 to 27 The working object distances differ, specifically in the distance from the image side of the third lens to the object side of the fourth lens. (Combined with...) Figure 25 , Figure 26 and Figure 27As shown, the machine vision lens provided in Embodiment 3 of the present invention includes a first lens 111, a second lens 112, a third lens 113, a fourth lens 114, a fifth lens 115, a sixth lens 116, a seventh lens 117, an eighth lens 118, a ninth lens 119, a tenth lens 120, an eleventh lens 121, and a twelfth lens 122 arranged sequentially along the optical axis from the object plane to the image plane. The first lens 111 is a positive power lens, the second lens 112 is a negative power lens, the third lens 113 is a negative power lens, the fourth lens 114 is a positive power lens, the fifth lens 115 is a positive power lens, the sixth lens 116 is a negative power lens, the seventh lens 117 is a positive power lens, the eighth lens 118 is a negative power lens, the ninth lens 119 is a negative power lens, the tenth lens 120 is a positive power lens, the eleventh lens 121 is a positive power lens, and the twelfth lens 122 is a negative power lens.

[0071] The lens setup is the same as in Embodiment 1, and will not be repeated here.

[0072] As another feasible implementation method, the specific parameters of the machine vision lens are explained below.

[0073] Table 7. Optical design values ​​for the machine vision lens in Example 3. Table 8. T34 Interval Distances Corresponding to Different Object Distances for Machine Vision Lenses Table 9 Design values ​​for a machine vision lens In Table 9 above, the surface numbers are assigned according to the surface order of each lens. "S1" represents the object-side surface of the first lens, "S2" represents the image-side surface of the first lens, and so on. "STO" represents the aperture stop of the lens. The radius of curvature represents the curvature of the lens surface; a positive value indicates that the surface bends towards the object plane, and a negative value indicates that the surface bends towards the image plane. "Infinite" indicates that the surface is flat and the radius of curvature is infinite. Thickness represents the central axial distance between the current surface and the next surface. nd represents the refractive index, which represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current position is air with a refractive index of 1. vd represents the Abbe constant, which represents the dispersion characteristics of the material between the current surface and the next surface. A blank space indicates that the current position is air. S22 represents the total thickness of the protective glass and the filter. The specific parameters of the machine vision lens corresponding to Embodiment 3 above are as follows: Focal length f: 3.974mm; Aperture: F#2.8; Total optical length (TTL): 53.1 mm; Optimal working distance: 300mm.

[0074] Furthermore, Figure 28 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the main working object distance, provided in Embodiment 3 of the present invention. The vertical direction represents the normalized aperture, 0 indicates on the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focal point, in millimeters (mm). Different linear curves in the figure represent different wavelengths of system imaging (e.g., 0.449μm, 0.510μm, 0.540μm, 0.570μm, 0.600μm, 0.640μm, and 0.680μm), which are determined by... Figure 28 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0075] Figure 29 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the closest object distance, provided in Embodiment 3 of the present invention. Figure 29 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0076] Figure 30 This is a schematic diagram of the spherical aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 3 of the present invention. Figure 30 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens is well controlled at each wavelength, which can meet the requirements of wide-spectrum applications.

[0077] Figure 31 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the main working object distance, provided in Embodiment 3 of the present invention. In the coordinate system on the left side of the figure, the horizontal axis represents the magnitude of the field curvature in mm; the vertical axis represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc distortion; Figure 31 As can be seen, the lens provided in this embodiment effectively controls the field curvature from light with wavelengths from 436nm to 656nm, meaning that during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 31As can be seen, the imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the lens distortion has been well corrected and the difference between the image and the actual object is small.

[0078] Figure 32 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the closest working object distance, provided in Embodiment 3 of the present invention. Figure 32 It can be seen that the lens provided in this embodiment effectively controls the field curvature of light from wavelength 436nm to 656nm. That is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small. The imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the distortion of the lens has been well corrected and the difference between the image and the actual object is small.

[0079] Figure 33 This is a schematic diagram of the field curvature distortion curve of a machine vision lens at the farthest working object distance, provided in Embodiment 3 of the present invention. Figure 33 It can be seen that the lens provided in this embodiment effectively controls the field curvature of light from wavelength 436nm to 656nm. That is, during imaging, the difference between the image quality in the center and the image quality in the periphery is small. The imaging distortion of the lens provided in this embodiment is less than 5%, indicating that the distortion of the lens has been well corrected and the difference between the image and the actual object is small.

[0080] Figure 34 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the main working object distance, provided in Embodiment 3 of the present invention. The vertical direction represents the image height, in mm; the horizontal direction represents the offset of different wavelengths from the optical axis at the image plane after passing through the system, in micrometers (μm). Different linear curves in the figure represent different wavelengths of the system imaging; the curves in the vertical direction on both sides of the figure are Airy disks, formed by... Figure 34 It can be seen that the transverse chromatic aberration of different wavelengths is mostly kept within the Airy disk, indicating that the lens has good control over chromatic aberration at various wavelengths and can meet the application requirements of a wide spectrum.

[0081] Figure 35 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the closest working object distance, provided in Embodiment 3 of the present invention. Figure 35 It can be seen that most of the wavelengths in the 450nm~640nm range remain within the Airy disk, indicating that the lens has good control over chromatic aberration at each wavelength, which can meet the application requirements of a wide spectrum.

[0082] Figure 36 This is a schematic diagram of the chromatic aberration curve of a machine vision lens at the farthest working object distance, provided in Embodiment 3 of the present invention. Figure 36It can be seen that most of the wavelengths in the 450nm~640nm range remain within the Airy disk, indicating that the lens has good control over chromatic aberration at each wavelength, which can meet the application requirements of a wide spectrum.

[0083] In summary, the machine vision lens provided by the embodiments of the present invention, by reasonably setting parameters such as the optical power, surface shape, Abbe number, refractive index, total optical length, and lens type of different lenses, ultimately achieves the design of a low-cost machine vision lens that can balance imaging requirements and small distortion. The machine vision lens has a maximum aperture of 2.8, a total optical length of 55mm, and can be matched with a maximum 1 / 1.8″ sensor chip. Its overall performance meets the requirements of the sensor used.

[0084] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A machine vision lens, characterized in that, It includes the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, tenth lens, eleventh lens and twelfth lens arranged sequentially along the optical axis from the object plane to the image plane; Wherein, the first lens is a positive optical power lens, the second lens is a negative optical power lens, the third lens is a negative optical power lens, the fourth lens is a positive optical power lens, the fifth lens is a positive optical power lens, the sixth lens is a negative optical power lens, the seventh lens is a positive optical power lens, the eighth lens is a negative optical power lens, the ninth lens is a negative optical power lens, the tenth lens is a positive optical power lens, the eleventh lens is a positive optical power lens, and the twelfth lens is a negative optical power lens; the machine vision lens contains twelve lenses with optical power. The fifth lens and the sixth lens are cemented together to form a first cemented lens; The seventh lens and the eighth lens form a second cemented lens; The eleventh lens and the twelfth lens form the fourth cemented lens; The third lens includes a third image-side surface near the image plane, and the fourth lens includes a fourth object-side surface near the object plane; the air gap between the third image-side surface and the fourth object-side surface on the optical axis is T34, and the total optical length of the machine vision lens system is TTL. Among them, 8.90≤TTL / T34≤17.1; The eighth lens includes an eighth image-side surface near the image plane; the ninth lens includes a ninth object-side surface near the object plane and a ninth image-side surface near the image plane; the tenth lens includes a tenth object-side surface near the object plane and a tenth image-side surface near the image plane; the eleventh lens includes an eleventh object-side surface near the object plane; the air gap between the eighth image-side surface and the ninth object-side surface on the optical axis is T89; the air gap between the ninth image-side surface and the tenth object-side surface on the optical axis is T910; the air gap between the tenth image-side surface and the eleventh object-side surface on the optical axis is T1011; and the back focal length of the machine vision lens is BFL. Among them, 5.82≤TTL / (T89+T910+T1011+BFL) ≤7.

40.

2. The machine vision lens according to claim 1, characterized in that, The seventh lens has a refractive index of Nd7 and an Abbe number of Vd7; the eighth lens has a refractive index of Nd8 and an Abbe number of Vd8. Among them, -0.39≤Nd7-Nd8≤-0.37, 20.3≤Vd7-Vd8≤48.

3. The machine vision lens according to claim 1, characterized in that, The eleventh lens has a refractive index of Nd11 and an Abbe number of Vd11; the twelfth lens has a refractive index of Nd12 and an Abbe number of Vd12. Among them, -0.6≤Nd11-Nd12≤-0.2, 46≤Vd11-Vd12≤74.

7.

4. The machine vision lens according to claim 1, characterized in that, The first lens includes a first object-side surface near the object plane and a first image-side surface near the image plane; the first object-side surface is convex, and the first image-side surface is concave; and the first lens is a meniscus lens. The second lens includes a second object-side surface near the object plane and a second image-side surface near the image plane; the second object-side surface is convex, and the second image-side surface is concave. The third lens also includes a third object-side surface near the object surface; the third object-side surface is a convex surface, a concave surface, or a plane, and the third image-side surface is a concave surface; The fourth lens also includes a fourth image-side surface near the image plane; the fourth image-side surface is a convex surface, a concave surface, or a plane, and the fourth image-side surface is a convex surface; The fifth lens includes a fifth object-side surface near the object plane and a fifth image-side surface near the image plane; the fifth object-side surface is concave and the fifth image-side surface is convex. The sixth lens includes a sixth object-side surface near the object plane and a sixth image-side surface near the image plane; the sixth object-side surface is concave and the sixth image-side surface is convex. The seventh lens includes a seventh object-side surface near the object plane and a seventh image-side surface near the image plane; the seventh object-side surface is concave and the seventh image-side surface is convex; and the seventh lens is a meniscus lens. The eighth lens also includes an eighth object-side surface near the object surface; the eighth object-side surface is concave, and the eighth image-side surface is convex; and the eighth lens is a meniscus lens; The ninth object side is convex, and the ninth image side is concave; and the ninth lens is a meniscus lens; The tenth object side surface is convex, and the tenth image side surface is convex; The eleventh lens also includes an eleventh image-side surface near the image plane; the eleventh object-side surface is convex, and the eleventh image-side surface is convex. The twelfth lens includes a twelfth object-side surface near the object plane and a twelfth image-side surface near the image plane; the twelfth object-side surface is concave and the twelfth image-side surface is convex; and the twelfth lens is a meniscus lens.

5. The machine vision lens according to claim 1, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens are all glass spherical lenses.

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