A high magnification and wide working distance line scan lens

Abstract

The present invention belongs to the field of lens technology, and specifically relates to a high-power wide working distance line scanning lens, comprising a mechanical system and an optical system installed inside the mechanical system, wherein the optical system sequentially arranges a first lens group S1, an aperture (1), and a second lens group S2 from the object side to the image side, and when the working distance changes, the first lens group S1, the aperture (1), and the second lens group S2 focus by moving back and forth. The present invention realizes a high-power wide working distance line scanning industrial lens, with a focal length of 116mm, a magnification of 0.425X-0.575X, an applicable working distance of 286mm-357mm, an image side F number of 4.8, a maximum imaging surface of φ82mm, a resolution of up to 100lp / mm, and a maximum optical distortion of the entire field of view of less than 0.035%.

Description

Technical Field

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

[0002] Driven by Industry 4.0, "automation" and "intelligence" have become the trend of modern industrial production. As an important part of "automation" and "intelligence", visual inspection systems have been widely used in various industries. Therefore, the application demand for industrial lenses, which are the core of visual inspection systems, is also increasing. In applications such as electronic manufacturing, LCD screen defect detection, printing detection, non-woven fabric detection, and smooth surface scratch and crack detection of mobile phone touch screens, the detection accuracy requirements are getting higher and higher, and it is necessary to rely on line scanning industrial lens imaging, especially in some online real-time detection projects. The performance of line scanning lenses directly affects the detection accuracy.

[0003] However, the optical performance of existing domestic line-scan industrial lenses always has shortcomings: large optical distortion, narrow working distance range, etc. Therefore, the research and development of line-scan industrial lenses with higher optical performance is more urgent.

[0004] At present, the machine vision lenses on the market, such as the patent with patent number "201710525728.X", support a working distance of 0.2m to infinity, but cannot meet the demand for closer working distances; another example is the patent with patent number "201621096764.6", which has a clear image at a working distance of 100mm-600mm, but its working distance range is too narrow; another example is the patent with patent number "201721433005.9", which has a working distance of 50mm-160mm, but its optical distortion is 0.05%, and the degree of distortion is relatively high. Summary of the invention

[0005] The purpose of the present invention is to develop a line scanning industrial lens with a resolution of 100lp / mm, low distortion, a large target surface, and good chromatic aberration correction capability in view of the shortcomings of the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A high-magnification, wide-working-distance line-scanning lens, comprising a mechanical system and an optical system installed inside the mechanical system, wherein the optical system sequentially arranges a first lens group S1, an aperture, and a second lens group S2 from the object side to the image side, and when the working distance changes, the first lens group S1, the aperture, and the second lens group S2 focus by moving forward and backward;

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

[0009] 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 meniscus structure;

[0010] The third lens G3 and the fourth lens G4 are cemented together to form a first cemented lens group U1 with negative optical power, and the fifth lens G5 and the sixth lens G6 are cemented together to form a second cemented lens group U2 with negative optical power;

[0011] The focal length of the optical system is f, and the focal length of the first cemented lens group U1 is f U1 , the focal length f of the second cemented lens group U2 U2 , f U1 The ratio of f satisfies the relationship: 0.50<|f U1 / f|<1.0;f U2 The ratio of f satisfies the relationship: 3.0<|f U2 / f|<5.0.

[0012] As an improvement of the high-magnification and wide-working-distance line-scan lens described in the present invention, the distance L between the vertex of the first lens G1 close to the object-side surface and the vertex of the seventh lens G7 close to the image-side surface and the focal length f of the optical system satisfy the relationship: 0.40<|L / f|.

[0013] As an improvement of the high-magnification and wide-working-distance line-scanning lens of the present invention, the distance from the seventh lens G7 of the optical system to the image plane, i.e., the optical back focus BFL, and the focal length f of the optical system satisfy the relationship: |BFL / f|<1.50.

[0014] As an improvement of the high-magnification and wide-working-distance line-scanning lens of the present invention, the half-image height y' of the optical system and the focal length f of the optical system satisfy the relationship: |y' / f|<0.50.

[0015] As an improvement of the high-magnification and wide-working-distance line-scanning lens system of the present invention, the refractive index of the first lens G1 is n1, and 1.40<n1<1.60.

[0016] As an improvement of the high-magnification and wide-working-distance line-scanning lens system of the present invention, the refractive index of the second lens G2 is n2, and 1.85<n2<1.95.

[0017] As an improvement of the high-magnification and wide-working-distance line-scanning lens of the present invention, the focal length of the third lens is f G3 , the focal length of the fourth lens is f G4 , f G3 and f U1 The ratio satisfies the relationship: 1.0<|f G3 / f U1 |<1.50,f G4 and f U1 The ratio satisfies the relationship: 0.35<|f G4 / f U1 |<0.60.

[0018] As an improvement of the high-magnification and wide-working-distance line-scanning lens of the present invention, the focal length of the fifth lens is f G5 , the focal length of the sixth lens is f G6 , f G5 and f G6 The ratio satisfies the relationship: 0.55<|f G5 / f G6 |<0.90.

[0019] As an improvement of the high-magnification and wide-working-distance line-scanning lens system described in the present invention, the refractive index of the seventh lens G7 is n7, and 1.85<n7<1.95.

[0020] As an improvement of the high-magnification and wide-working-distance line-scanning lens described in the present invention, each of the lenses is a spherical mirror, the aperture of the diaphragm is a circular hole, and the aperture of the diaphragm is adjustable within the range of F4.8 to F32.

[0021] The beneficial effects of the present invention are as follows: the above structure realizes a line scanning lens with a high magnification, wide working distance and a focal length of 116 mm, a focal length of 116 mm, a magnification of 0.425X-0.575X, an applicable working distance of 286mm-357mm, an image side F number of 4.8, a maximum imaging surface of φ82mm, and a resolution of up to 100lp / mm, that is, when the corresponding maximum imaging chip is used, its pixels can reach 16K pixels, and the maximum optical distortion of the full field of view is less than 0.035%; by adopting the whole group focusing method, 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 the lens optical system of the first embodiment;

[0024] Figure 2 is an optical distortion curve diagram of the lens optical system of Example 1;

[0025] 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; U1-first cemented lens group; U2-second cemented lens group. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] This embodiment provides a high-magnification and wide-working-distance line scanning lens, comprising a mechanical system and an optical system installed inside the mechanical system, wherein the optical system sequentially arranges a first lens group S1, an aperture 1, and a second lens group S2 from the object side to the image side, and when the working distance changes, the first lens group S1, the aperture 1, and the second lens group S2 focus by moving forward and backward;

[0031] The first lens group S1 includes a first lens G1 with positive power and a meniscus structure, a second lens G2 with positive power and a meniscus structure, a third lens G3 with positive power and a meniscus structure, and a fourth lens G4 with negative power and a meniscus structure.

[0032] 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 meniscus structure;

[0033] The third lens G3 and the fourth lens G4 are cemented together to form a first cemented lens group U1 with negative power, and the fifth lens G5 and the sixth lens G6 are cemented together to form a second cemented lens group U2 with negative power;

[0034] The focal length of the optical system is f, and the focal length of the first cemented lens group U1 is f U1 , the focal length f of the second cemented lens group U2 U2 , f U1 The ratio of f satisfies the relationship: 0.50<|f U1 / f|<1.0;f U2 The ratio of f satisfies the relationship: 3.0<|f U2 / f|<5.0.

[0035] Furthermore, a distance L between a vertex of the first lens G1 close to the object-side surface and a vertex of the seventh lens G7 close to the image-side surface and a focal length f of the optical system satisfy the relationship: 0.40<|L / f|.

[0036] Furthermore, the distance from the seventh lens G7 of the optical system to the image plane 2, that is, the optical back focus BFL and the focal length f of the optical system satisfy the relationship: |BFL / f|<1.50.

[0037] Furthermore, the half-image height y' of the optical system and the focal length f of the optical system satisfy the relationship: |y' / f|<0.50.

[0038] Furthermore, the refractive index of the first lens G1 is n1, and 1.40<n1<1.60.

[0039] Furthermore, the refractive index of the second lens G2 is n2, and 1.85<n2<1.95.

[0040] Furthermore, the focal length of the third lens is f G3 , the focal length of the fourth lens is f G4 , f G3 and f U1 The ratio satisfies the relationship: 1.0<|f G3 / f U1 |<1.50,fG4 and f U1 The ratio satisfies the relationship: 0.35<|f G4 / f U1 |<0.60.

[0041] Furthermore, the focal length of the fifth lens is f G5 , the focal length of the sixth lens is f G6 , f G5 and f G6 The ratio satisfies the relationship: 0.55<|f G5 / f G6 |<0.90.

[0042] Furthermore, the refractive index of the seventh lens G7 is n7, and 1.85<n7<1.95.

[0043] Furthermore, each lens is a spherical mirror, the aperture of the diaphragm 1 is a circular hole, and the aperture of the diaphragm 1 is adjustable within the range of F4.8 to F32.

[0044] Embodiment 1: Figure 1 As shown, the above structure realizes a high-magnification and wide-working-distance line-scanning industrial lens, with a focal length of 116mm, a magnification of 0.425X-0.575X, an applicable working distance of 286mm-357mm, an image-side F number of 4.8, a maximum imaging surface of φ82mm, and a resolution of up to 100lp / mm, that is, when the corresponding maximum imaging chip is used, its pixels can reach 16K pixels, and the maximum optical distortion of the full field of view is less than 0.035%; the whole-group focusing method is adopted, and its aperture can also be flexibly adjusted. The specific optical system data are as follows:

[0045] surface Radius(mm) Thickness(mm) Refractive Index G1 front surface 62.1 4.6 1.45 G1 rear surface 455.0 0.1 G2 front surface 54.8 7.1 1.90 G2 rear surface 73.2 0.1 U1 front surface 37.5 4.1 1.45 U1 Gluing Surface 90.0 10.0 1.80 U1 rear surface 26.7 11.2 Aperture flat 9.6 U2 front surface -38.6 10.0 1.70 U2 glue surface 78.0 8.1 1.80 U2 rear surface -56.9 0.1 G7 front surface -5551.0 4.0 1.90 G7 rear surface -120.9 123.3 Image plane flat

[0046] In Example 1, the focal length f of the optical system is 116 mm, the maximum aperture is F#=4.8, and the focal length f of the first cemented lens group is U1 =-101.1mm, the focal length of the second cemented lens group is f U2 =-464.6mm, the distance L from the front surface vertex of the first lens G1 to the back surface vertex of the seventh lens G7 = 69.9mm, the optical back focus BFL = 123.3mm, the half image height y' = 41.0mm, the focal length f of the third lens G3 G3 =125.9mm, the focal length of the fourth lens G4 is f G4 =-50.3mm, the focal length of the fifth lens G5 is f G5 =-32.7mm, the focal length of the sixth lens G6 is f G6 =42.0mm

[0047] Each relation: |f U1 / f|=0.87;|f U2 / f|=4.01;|L / f|=0.60;

[0048] |BFL / f|=1.06; |y' / f|=0.35; |f G3 / f U1 |=1.25;|f G4 / f U1 |=0.50

[0049] |f G5 / f G6 |=0.78

[0050] Satisfy the relationship: 0.50<|f U1 / f|<1.0;3.0<|f U2 / f|<5.0;0.40<|L / f|

[0051] |BFL / f|<1.50; |y' / f|<0.50; 1.0<|f G3 / f U1 |<1.50;

[0052] 0.35<|f G4 / f U1 |<0.60;0.55<|f G5 / f G6 |<0.90.

[0053] Figure 2 The optical distortion curve of this embodiment is shown, and the maximum optical distortion in the whole field of view is less than 0.035%;

[0054] 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 magnification and wide working distance line scan lens, characterized in that: The invention comprises a mechanical system and an optical system installed inside the mechanical system, wherein the optical system is provided with a first lens group S1, an aperture (1), and a second lens group S2 in sequence from the object side to the image side, and when the working distance changes, the first lens group S1, the aperture (1), and the second lens group S2 focus by moving forward and backward; The first lens group S1 includes a first lens G1 with positive focal power and a meniscus structure, a second lens G2 with positive focal power and a meniscus structure, a third lens G3 with positive focal power and a meniscus structure, and a fourth lens G4 with negative focal power and a meniscus structure; 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 meniscus structure; The third lens G3 and the fourth lens G4 are cemented together to form a first cemented lens group U1 with negative optical power, and the fifth lens G5 and the sixth lens G6 are cemented together to form a second cemented lens group U2 with negative optical power; The focal length of the optical system is f, and the focal length of the first cemented lens group U1 is f U1 , the focal length f of the second cemented lens group U2 U2 , f U1 The ratio of f satisfies the relationship: 0.50<|f U1 / f|<1.0;f U2 The ratio of f satisfies the relationship: 3.0<|f U2 / f|<5.0; A distance L between the vertex of the first lens G1 close to the object-side surface and the vertex of the seventh lens G7 close to the image-side surface and a focal length f of the optical system satisfy the relationship: 0.40<|L / f|; The distance between the seventh lens G7 of the optical system and the image plane (2), i.e., the optical back focus BFL, and the focal length f of the optical system satisfy the relationship: |BFL / f|<1.50 The half image height y' of the optical system and the focal length f of the optical system satisfy the relationship: |y' / f|<0.50; The focal length of the third lens is f G3 , the focal length of the fourth lens is f G4 , f G3 and f U1 The ratio satisfies the relationship: 1.0<|f G3 / f U1 |<1.50,f G4 and f U1 The ratio satisfies the relationship: 0.35<|f G4 / f U1 |<0.60; The focal length of the fifth lens is f G5 , the focal length of the sixth lens is f G6 , f G5 and f G6 The ratio satisfies the relationship: 0.55<|f G5 / f G6 |<0.

90.

2. The high-magnification and wide-working-distance line-scanning lens according to claim 1, characterized in that: The refractive index of the first lens G1 is n1, and 1.40<n1<1.

60.

3. The high-magnification and wide-working-distance line-scanning lens according to claim 1, characterized in that: The refractive index of the second lens G2 is n2, and 1.85<n2<1.

95.

4. The high-magnification and wide-working-distance line-scanning 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-magnification and wide-working-distance line-scanning lens according to claim 1, characterized in that: Each of the lenses is a spherical mirror, the aperture of the diaphragm (1) is a circular hole, and the aperture of the diaphragm (1) is adjustable within the range of F4.8 to F32.

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