A low distortion industrial lens with high resolution and wide working distance

Abstract

The present invention belongs to the field of lens technology, and specifically relates to a low-distortion industrial lens with high resolution and wide working distance, comprising a mechanical device and an optical module installed inside the mechanical device, wherein the optical module is sequentially provided with a focusing group and a fixed group from the object side to the image side, and the focusing group comprises a first lens group, an aperture and a second lens group; the focal length f of the optical module, the focal length of the first lens group is f1, the focal length of the second lens group is f2, and the focal length of the fixed group is f3, 2.5<|f1 / f|<5.0; 1.0<|f2 / f|<2.0; 2.0<|f3 / f|<3.0. The focal length of the optical module of the lens of the present invention is 25mm, the maximum imaging surface is φ17.6mm, the resolution can reach 200lp / mm, and the optical distortion of the full field of view is less than 0.5%; the working distance is wide, and a floating focus method is adopted, and the imaging requirements can be met from 250mm to ∞.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial lenses, and in particular relates to a low-distortion industrial lens with high resolution and wide working distance. Background Art

[0002] Driven by industrial automation, industrial lenses are constantly developing. As application demands continue to increase, the requirements for industrial lenses are also getting higher and higher. Especially in some applications such as defect detection, positioning monitoring, and color sorting, the optical distortion, applicable working distance range, and resolution of industrial lenses are required to be high; and the existing industrial lenses in China generally have different types or degrees of defects such as small target surface, low pixel, narrow working distance, and large distortion. Therefore, the research and development of industrial lenses with high pixels, low distortion, and wide working distance is more urgent.

[0003] At present, the machine vision lenses on the market, such as the patent with the patent number "201710504554.9", have a circular target surface diameter of only 43mm, an optical distortion of 2%, and a resolution of only 6 million; another example is the patent with the patent number "201811365245.9", which has a clear image at a working distance of 300mm and a distortion rate of less than 0.5%; another example is the patent with the patent number "201820151902.9", which has an optical distortion of less than 0.1%, but its pixels are only 5 million. Summary of the invention

[0004] The purpose of the present invention is to develop a low-distortion industrial lens with high resolution, wide working distance and meet the needs of industrial development in view of the shortcomings of the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A low-distortion industrial lens with high resolution and wide working distance, comprising a mechanical device and an optical module installed inside the mechanical device, wherein the optical module is provided with a focus group and a fixed group S3 in sequence from the object side to the image side, and when the working distance changes, the air interval between the focus group and the fixed group S3 is changed to adjust the focus;

[0007] The focusing group includes a first lens group S1, an aperture and a second lens group S2;

[0008] The first lens group S1 includes a first lens G1 with negative power and a meniscus structure, a second lens G2 with positive power and a biconvex structure, a third lens G3 with positive power and a biconvex structure, and a fourth lens G4 with negative power and a biconcave structure.

[0009] The second lens group S2 includes a fifth lens G5 with negative optical power and a biconcave structure, a sixth lens G6 with positive optical power and a biconvex structure, and a seventh lens G7 with positive optical power and a biconvex structure;

[0010] The fixed group S3 includes an eighth lens G8 with negative optical power and a meniscus structure, and a ninth lens G9 with positive optical power and a biconvex structure;

[0011] The focal length f of the optical module, the focal length of the first lens group S1 is f1, the focal length of the second lens group S2 is f2, the focal length of the fixed group S3 is f3, the ratio of f1 to f satisfies the relationship: 2.5<|f1 / f|<5.0; the ratio of f2 to f satisfies the relationship: 1.0<|f2 / f|<2.0; the ratio of f3 to f satisfies the relationship: 2.0<|f3 / f|<3.0.

[0012] As an improvement of the high-resolution, wide-working-distance, low-distortion industrial lens described in the present invention, the distance from the ninth lens G9 of the optical module to the image plane, i.e., the optical back focus BFL, and the focal length f of the optical module satisfy the relationship: |BFL / f|<1.0.

[0013] As an improvement of the high-resolution, wide-working-distance, low-distortion industrial lens of the present invention, the half-image height y' of the optical module and the focal length f of the optical module satisfy the relationship: |y' / f|<0.4.

[0014] As an improvement of the industrial lens with high resolution, wide working distance and low distortion described in the present invention, the refractive index of the first lens G1 is n1, and 1.45<n1<1.55.

[0015] As an improvement of the industrial lens with high resolution, wide working distance and low distortion described in the present invention, the refractive index of the second lens G2 is n2, and 1.75<n2<1.90.

[0016] As an improvement of the high-resolution, wide-working-distance, low-distortion industrial lens of the present invention, the third lens G3 and the fourth lens G4 are glued together to form a first glued lens group U1, and the focal length of the first glued lens group U1 is f u1 , f u1 The ratio of f1 satisfies the relationship: 0.5<|f u1 / f1|<1.0.

[0017] As an improvement of the high-resolution, wide-working-distance, low-distortion industrial lens of the present invention, the fifth lens G5 and the sixth lens G6 are glued together to form a second glued lens group U2, and the focal length of the second glued lens group U2 is f u2 , f u2The ratio of f2 satisfies the relationship: 1.0<|f u2 / f2|<1.5.

[0018] As an improvement of the high-resolution, wide-working-distance, low-distortion industrial lens of the present invention, the refractive index of the seventh lens G7 is n7, and 1.85<n7<1.95.

[0019] As an improvement of the high-resolution, wide-working-distance, low-distortion industrial lens of the present invention, the eighth lens G8 and the ninth lens G9 are cemented together to form a third cemented lens group U3, and the focal length of the eighth lens G8 is f G8 , the focal length of the ninth lens G9 is f G9 , f G8 The ratio of f3 satisfies the relationship: 0.3<|f G8 / f3|<0.45,f G9 The ratio of f3 satisfies the relationship: 0.3<|f G9 / f3|<0.45.

[0020] As an improvement of the low-distortion industrial lens with high resolution, wide working distance and low distortion described in the present invention, each of the lenses is a spherical mirror.

[0021] The beneficial effects of the present invention are as follows: an optical module of a low-distortion industrial lens with a focal length of 25 mm, high resolution, wide working distance, and a maximum imaging surface of φ17.6 mm is realized through the above structure, and its resolution can reach 200 lp / mm, the maximum pixel can reach 23 million pixels, and the full-field optical distortion is less than 0.5%; the working distance is wide, and a floating focus method is adopted, and the corresponding imaging requirements can be met from 250 mm to ∞, which can meet different application requirements, and its light aperture can also be flexibly adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1 It is a diagram of a lens optical module of an embodiment;

[0024] Figure 2 is a light path diagram of the lens optical module of an embodiment;

[0025] Figure 3 is an optical distortion curve diagram of the lens optical module of an embodiment;

[0026] In the figure: 1-aperture, 2-image plane, G1-first lens, G2-second lens, G3-third lens, G4-fourth lens, G5-fifth lens, G6-sixth lens, G7-seventh lens, G8-eighth lens, G9-ninth lens, U1-first cemented lens group, U2-second cemented lens group, U3-third cemented lens group, S1-first lens group, S2-second lens group, S3-fixed group. DETAILED DESCRIPTION

[0027] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect.

[0028] In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "horizontal", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings, but this is not intended to limit the present invention.

[0031] Example

[0032] like Figure 1 As shown, this embodiment provides a low-distortion industrial lens with high resolution and wide working distance, including a mechanical device and an optical module installed inside the mechanical device. The optical module is sequentially provided with a focus group and a fixed group S3 from the object side to the image side. When the working distance changes, the air gap between the focus group and the fixed group S3 is changed to adjust the focus;

[0033] The focusing group includes a first lens group S1, an aperture 1 and a second lens group S2;

[0034] The first lens group S1 includes a first lens G1 with negative power and a meniscus structure, a second lens G2 with positive power and a biconvex structure, a third lens G3 with positive power and a biconvex structure, and a fourth lens G4 with negative power and a biconcave structure.

[0035] The second lens group S2 includes a fifth lens G5 with negative power and a biconcave structure, a sixth lens G6 with positive power and a biconvex structure, and a seventh lens G7 with positive power and a biconvex structure;

[0036] The fixed group S3 includes an eighth lens G8 with negative optical power and a meniscus structure, and a ninth lens G9 with positive optical power and a biconvex structure;

[0037] The focal length f of the optical module, the focal length of the first lens group S1 is f1, the focal length of the second lens group S2 is f2, the focal length of the fixed group S3 is f3, the ratio of f1 to f satisfies the relationship: 2.5<|f1 / f|<5.0; the ratio of f2 to f satisfies the relationship: 1.0<|f2 / f|<2.0; the ratio of f3 to f satisfies the relationship: 2.0<|f3 / f|<3.0.

[0038] Furthermore, the distance from the ninth lens G9 of the optical module to the image plane 2, ie, the optical back focus BFL, and the focal length f of the optical module satisfy the relationship: |BFL / f|<1.0.

[0039] Furthermore, the half image height y' of the optical module and the focal length f of the optical module satisfy the relationship: |y' / f|<0.4.

[0040] Furthermore, the refractive index of the first lens G1 is n1, and 1.45<n1<1.55.

[0041] Furthermore, the refractive index of the second lens G2 is n2, and 1.75<n2<1.90.

[0042] Furthermore, the third lens G3 and the fourth lens G4 are cemented together to form a first cemented lens group U1. The focal length of the first cemented lens group U1 is f u1 , f u1 The ratio of f1 satisfies the relationship: 0.5<|f u1 / f1|<1.0.

[0043] Furthermore, the fifth lens G5 and the sixth lens G6 are cemented together to form a second cemented lens group U2. The focal length of the second cemented lens group U2 is f u2 , f u2The ratio of f2 satisfies the relationship: 1.0<|f u2 / f2|<1.5.

[0044] Furthermore, the refractive index of the seventh lens G7 is n7, and 1.85<n7<1.95.

[0045] Furthermore, the eighth lens G8 and the ninth lens G9 are cemented together to form a third cemented lens group U3, and the focal length of the eighth lens G8 is f G8 , the focal length of the ninth lens G9 is f G9 , f G8 The ratio of f3 satisfies the relationship: 0.3<|f G8 / f3|<0.45,f G9 The ratio of f3 satisfies the relationship: 0.3<|f G9 / f3|<0.45.

[0046] Furthermore, each lens is a spherical mirror.

[0047] The specific optical module data are as follows:

[0048]

[0049]

[0050] In this embodiment, the focal length f of the optical module is 25 mm, the maximum aperture is F#=2.8, the focal length f1 of the first lens group S1 is 86.4 mm, the focal length f2 of the second lens group S2 is 36.1 mm, the focal length f3 of the fixed group S3 is 58.6 mm, and the focal length f of the first cemented lens group U1 is U1 =83.9mm, the focal length of the second cemented lens group U2 is f U2 =-44.7mm, the focal length of the eighth lens G8 is f G8 =-25.7mm, the focal length of the ninth lens G9 is f G9 =17.9mm, optical back focus BFL=13.6mm, half image height y'=8.8mm.

[0051] Relational equations: |f1 / f|=3.45; |f2 / f|=1.44; |f3 / f|=2.34; |BFL / f|=0.54; |y' / f|=0.35; |f U1 / f1|=0.97;|f U2 / f2|=1.23;|f G8 / f3|=0.43;|f G9 / f3|=0.1.

[0052] Satisfy the relationship: 2.5<|f1 / f|<5.0; 1.0<|f2 / f|<2.0; 2.0<|f3 / f|<3.0; |BFL / f|<1.0; |y' / f|<0.4; 0.5<|f U1 / f1|<1.0;1.0<|f U2 / f2|<1.5;0.3<|f G8 / f3|、|f G9 / f3|<0.45.

[0053] Figure 3 The optical distortion curve of this embodiment is shown, and the maximum optical distortion in the whole field of view is less than 0.5%.

[0054] The above structure realizes an optical module of a low-distortion industrial lens with a focal length of 25mm, high resolution, wide working distance, and a maximum imaging surface of φ17.6mm. The resolution can reach 200lp / mm, the maximum pixel can reach 23 million pixels, and the full-field optical distortion is less than 0.5%. The working distance is wide and a floating focus method is adopted. The corresponding imaging requirements can be met from 250mm to ∞, which can meet different application requirements. At the same time, the light aperture can also be flexibly adjusted.

[0055] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not depart from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A high-resolution, wide-working-distance, low-distortion industrial lens, characterized in that: It comprises a mechanical device and an optical module installed inside the mechanical device, wherein the optical module is provided with a focus group and a fixed group S3 in sequence from the object side to the image side, and when the working distance changes, the air interval between the focus group and the fixed group S3 is changed to adjust the focus; The focusing group comprises a first lens group S1, an aperture (1) and a second lens group S2; The first lens group S1 includes a first lens G1 with negative power and a meniscus structure, a second lens G2 with positive power and a biconvex structure, a third lens G3 with positive power and a biconvex structure, and a fourth lens G4 with negative power and a biconcave structure. The second lens group S2 includes a fifth lens G5 with negative optical power and a biconcave structure, a sixth lens G6 with positive optical power and a biconvex structure, and a seventh lens G7 with positive optical power and a biconvex structure; The fixed group S3 includes an eighth lens G8 with negative optical power and a meniscus structure, and a ninth lens G9 with positive optical power and a biconvex structure; The focal length f of the optical module, the focal length of the first lens group S1 is f1, the focal length of the second lens group S2 is f2, the focal length of the fixed lens group S3 is f3, the ratio of f1 to f satisfies the relationship: 2.5<|f1 / f|<5.0; the ratio of f2 to f satisfies the relationship: 1.0<|f2 / f|<2.0; the ratio of f3 to f satisfies the relationship: 2.0<|f3 / f|<3.0; The distance between the ninth lens G9 of the optical module and the image plane (2), i.e., the optical back focus BFL, and the focal length f of the optical module satisfy the relationship: |BFL / f|<1.0; The half image height y' of the optical module and the focal length f of the optical module satisfy the relationship: |y' / f|<0.4; The third lens G3 and the fourth lens G4 are cemented together to form a first cemented lens group U1. The focal length of the first cemented lens group U1 is f u1 , f u1 The ratio of f1 satisfies the relationship: 0.5<|f u1 / f1|<1.0; The fifth lens G5 and the sixth lens G6 are cemented together to form a second cemented lens group U2. The focal length of the second cemented lens group U2 is f u2 , f u2 The ratio of f2 satisfies the relationship: 1.0<|f u2 / f2|<1.5; The eighth lens G8 and the ninth lens G9 are cemented together to form a third cemented lens group U3. The focal length of the eighth lens G8 is f G8 , the focal length of the ninth lens G9 is f G9 , f G8 The ratio of f3 satisfies the relationship: 0.3<|f G8 / f3|<0.45,f G9 The ratio of f3 satisfies the relationship: 0.3<|f G9 / f3|<0.

45.

2. The high-resolution, wide-working-distance, low-distortion industrial lens according to claim 1, characterized in that: The refractive index of the first lens G1 is n1, and 1.45<n1<1.

55.

3. The high-resolution, wide-working-distance, low-distortion industrial lens according to claim 1, characterized in that: The refractive index of the second lens G2 is n2, and 1.75<n2<1.

90.

4. The high-resolution, wide-working-distance, low-distortion industrial lens according to claim 1, characterized in that: The refractive index of the seventh lens G7 is n7, and 1.85<n7<1.

95.

5. The high-resolution, wide-working-distance, low-distortion industrial lens according to claim 1, characterized in that: Each of the lenses is a spherical mirror.

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