CN209690608U - A low distortion lens - Google Patents

Abstract

The utility model discloses a low distortion lens, which comprises a front lens group (1), a middle lens group (2), a diaphragm (5), a rear lens group (3) and a focusing group (4) which are arranged in sequence from an object side to an image side along an optical axis; the focal length of the optical system is f, and the focal length of the front lens group (1) is f₁The focal length of the middle lens group (2) is f₂The focal length of the rear lens group (3) is f₃The focal length of the focusing group (4) is f₄Respectively satisfy the relational expressions: 1.5<|f₁/f|<4.0；0.5<|f₂/f|<1.5；1.0<|f₃/f|<2.0；5.0<|f₄/f|<10.0. The utility model has the characteristics of the distortion is low, can effectively reduce the distortion degree of image to adopt and floatThe focusing mode meets the imaging requirement of the working distance of more than 300mm and different application requirements, and meanwhile, the clear aperture of the focusing lens can be flexibly adjusted.

Description

A low distortion lens

technical field

The utility model belongs to the technical field of lenses, in particular to a low-distortion lens.

Background technique

Machine vision is the use of machines instead of human eyes for measurement and judgment. The machine vision system refers to converting the target information to be detected into image signals through the image capture device, and then the image processing system performs various operations on these signals to extract the target features, so as to realize the measurement, detection and recognition of the target. With the implementation of the Made in China 2025 strategy and the rapid development of industrial automation, machine vision is widely used in manufacturing, quality inspection, logistics, medicine, scientific research and other fields, and the lens as the "eye" of machine vision occupies an important position. In the application scenarios of electronic product manufacturing, such as liquid crystal screen defect detection, mobile phone touch screen circuit, etc., the requirements for high-quality lenses are getting higher and higher.

Among them, the Chinese patent literature discloses a lens (publication number: CN 107632376 A, comprising: a first lens group forming a fixed group and a second lens group forming a focusing group arranged in sequence along the optical axis from the object side to the image side , aperture and the third lens group; the first lens group is a negative power lens group; the second lens group and the third lens group are positive power lens groups; the first lens group consists of Three lenses are made up; the second lens group includes at least three lenses; the third lens group is made up of four lenses.Above-mentioned scheme can improve pixel to a certain extent, but there are following defects at least in this scheme: First, the structure is complex; second, the optical distortion is large, which cannot meet the needs of current visual lenses.

Utility model content

The purpose of the utility model is to provide a low-distortion lens with the characteristics of low distortion, which can effectively reduce the degree of distortion of the image, and adopt the floating focus mode to meet the imaging requirements of more than 300mm and different Application requirements, and its clear aperture can also be adjusted flexibly.

In order to achieve the above object, the utility model adopts the following technical solutions:

A low-distortion lens, comprising a front lens group, a middle lens group, a diaphragm, a rear lens group and a focusing group arranged sequentially along the optical axis from the object side to the image side;

The front lens group includes a first lens G1 with a positive power and a meniscus structure, a second lens G2 with a positive power and a meniscus structure, and a negative light lens arranged in sequence from the object side to the image side along the optical axis. Third lens G3 with focal power and meniscus structure;

The middle lens group includes the fourth lens G4 with negative refractive power and meniscus structure, the fifth lens G5 with positive refractive power and biconvex structure, and the fifth lens G5 with positive optical power arranged in sequence from the object side to the image side along the optical axis. The sixth lens G6 with high power and biconvex structure, and the seventh lens G7 with negative power and biconcave structure;

The rear lens group includes an eighth lens G8 with a positive refractive power and a meniscus structure, and a ninth lens G9 with a negative refractive power and a meniscus structure, arranged in sequence from the object side to the image side along the optical axis;

The focusing group includes a tenth lens G10 with positive refractive power and a biconvex structure, and an eleventh lens G11 with negative refractive power and a biconcave structure, arranged in sequence from the object side to the image side along the optical axis;

_The focal length of the optical system is _f , the focal length of the front lens group is f1, the focal length of the middle lens group is f2, the focal length of the rear lens group is _f3 , and the focal length of the focusing group is f ₄ , respectively satisfy the relation: 1.5<|f ₁ /f|<4.0;0.5<|f ₂ /f|<1.5;1.0<|f ₃ /f|<2.0;5.0<|f ₄ /f|< 10.0.

As an improvement of the low-distortion lens described in the present invention, the optical back focus of the optical system is BFL, which satisfies the relationship with the focal length f of the optical system: |BFL/f|<1.5.

As an improvement of the low-distortion lens described in the present invention, the half-image height of the optical system is y', which satisfies the relationship with the focal length f of the optical system: |y'/f|<0.5 .

As an improvement of the low-distortion lens described in the present invention, the refractive index of the first lens G1 is n1, and the refractive index of the first lens G1 satisfies the relationship: 1.8<n1<2.1.

As an improvement of the low-distortion lens described in the present invention, the refractive index of the second lens G2 is n2, and the refractive index of the third lens G3 is n3, both of which satisfy the relational formula: 1.65< n2<1.9; 1.65<n3<1.9; the Abbe coefficient of the second lens G2 is v2, and the Abbe coefficient of the third lens G3 is v3, both of which satisfy the relationship: 20<v2<35; 40 <v3<60.

As an improvement of the low-distortion lens described in the present invention, the fourth lens G4 and the fifth lens G5 form a first cemented lens U1, and the sixth lens G6 and the seventh lens G7 forms the second cemented lens U2, the focal length of the first cemented lens U1 is f _U1 , the focal length of the second cemented lens U2 is f _U2 , the focal length of the first cemented lens U1 and the middle lens group The ratio of the focal length of the second cemented lens U2 satisfies the relational expression: 0.9<|f _U1 /f ₂ |<2.0, and the ratio of the focal length of the second cemented lens U2 to the focal length of the middle lens group satisfies the relational expression: 3.0<|f _U2 /f ₂ |<6.0.

As an improvement of the low-distortion lens described in the present invention, the focal length of the tenth lens G10 is f _G10 , the focal length of the eleventh lens G11 is f _G11 , and the focal length of the tenth lens G10 is The ratio to the focal length of the focusing group and the ratio of the eleventh lens G11 to the focal length of the focusing group satisfy the relationship: 0.05<|f _G10 /f ₄ |<0.2;0.05<|f _G11 /f ₄ |<0.2.

As an improvement of the low-distortion lens described in the present invention, the eighth lens G8 and the ninth lens G9 form a third cemented lens U3.

As an improvement of the low-distortion lens described in the present invention, the refractive index of the eighth lens G8 is n8, and the refractive index of the ninth lens G9 is n9, both of which satisfy the relationship: 1.7< n8<2.1; 1.7<n9<2.1; the Abbe coefficient of the eighth lens G8 is v8, and the Abbe coefficient of the ninth lens G9 is v9, both of which satisfy the relationship: 40<v8<60; 20 <v9<35.

As an improvement of the low distortion lens described in the present invention, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7, the eighth lens G8, the ninth lens G9, the tenth lens G10 and the eleventh lens G11 are all spherical mirrors.

The beneficial effect of the utility model is that the utility model comprises a front lens group, a middle lens group, a diaphragm, a rear lens group and a focusing group which are sequentially arranged along the optical axis from the object side to the image side; The first lens G1 with positive refractive power and a meniscus structure, the second lens G2 with positive refractive power and a meniscus structure, and the lens G2 with negative refractive power and a meniscus structure are arranged in sequence from the object side to the image side. The third lens G3; the middle lens group includes the fourth lens G4 with negative refractive power and meniscus structure arranged in sequence along the optical axis from the object side to the image side, and the fifth lens with positive refractive power and biconvex structure G5, the sixth lens G6 with positive refractive power and biconvex structure, and the seventh lens G7 with negative refractive power and biconcave structure; the rear lens group includes sequentially arranged along the optical axis from the object side to the image side The eighth lens G8 with positive refractive power and meniscus structure, and the ninth lens G9 with negative refractive power and meniscus structure; The tenth lens G10 with focal power and double-convex structure, and the eleventh lens G11 with negative refractive power and double-concave structure; the focal length of the optical system is f, and the focal length of the front lens group is f ₁ , so The focal length of the above-mentioned lens group is f ₂ , the focal length of the rear lens group is f ₃ , and the focal length of the focusing group is f ₄ , which respectively satisfy the relationship: 1.5<|f ₁ /f|<4.0;0.5< |f ₂ /f|<1.5;1.0<|f ₃ /f|<2.0;5.0<|f ₄ /f|<10.0. Through the above structure, the optical system of a low-distortion lens with a focal length of 75mm, high pixels and wide working distance is realized, and the maximum imaging surface is Its resolution can reach 140lp/mm, the highest pixel can reach 70 million pixels, and the optical distortion of the whole field of view is less than 0.03%. Different application requirements, and its clear aperture can also be flexibly adjusted. The utility model has the characteristics of low distortion, can effectively reduce the degree of image distortion, effectively improve the detection accuracy, and adopts a floating focusing method to meet the imaging requirements of more than 300mm and different application requirements, and its clear aperture can also be flexibly adjusted.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the light path figure of the utility model;

Fig. 3 is the transfer function diagram of the present utility model;

Fig. 4 is the optical distortion curve figure of the present utility model;

Among them: 1-front lens group; 2-middle lens group; 3-rear lens group; 4-focusing group; 5-stop.

Detailed ways

Certain terms are used, for example, in the description and claims to refer to particular components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in name as a way to distinguish components, but use the difference in function of components as a criterion for distinguishing. As mentioned throughout the specification and claims, "comprising" 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 technical problems within a certain error range and basically achieve technical effects.

In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", horizontal" etc. are based on the attached The orientation or positional relationship shown in the figure is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as Limitations on the Invention.

In the utility model, unless otherwise clearly stipulated and limited, the terms "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present utility model according to specific situations.

The utility model will be described in further detail below in conjunction with the accompanying drawings, but not as a limitation to the utility model.

As shown in Figures 1 to 4, a low-distortion lens includes a front lens group 1, a middle lens group 2, a diaphragm 5, a rear lens group 3 and a focusing group 4 arranged in sequence along the optical axis from the object side to the image side ;

The front lens group 1 includes a first lens G1 with positive refractive power and a meniscus structure, a second lens G2 with positive refractive power and a meniscus structure, and a lens with negative focal power arranged in sequence from the object side to the image side along the optical axis. The third lens G3 with degree and meniscus structure;

The middle lens group 2 includes the fourth lens G4 with negative refractive power and meniscus structure, the fifth lens G5 with positive refractive power and biconvex structure, and the fifth lens G5 with positive refractive power arranged in sequence from the object side to the image side along the optical axis. And the sixth lens G6 with biconvex structure, and the seventh lens G7 with negative refractive power and biconcave structure;

The rear lens group 3 includes an eighth lens G8 with a positive refractive power and a meniscus structure, and a ninth lens G9 with a negative refractive power and a meniscus structure, arranged in sequence along the optical axis from the object side to the image side;

The focusing group 4 includes a tenth lens G10 with positive power and a biconvex structure, and an eleventh lens G11 with negative power and a biconcave structure, which are arranged sequentially along the optical axis from the object side to the image side;

The focal length of the optical system is f, the focal length of the front lens group 1 is f ₁ , the focal length of the middle lens group 2 is f ₂ , the focal length of the rear lens group 3 is f ₃ , and the focal length of the focusing group 4 is f ₄ , respectively satisfying the relationship Formula: 1.5<|f ₁ /f|<4.0;0.5<|f ₂ /f|<1.5;1.0<|f ₃ /f|<2.0;5.0<|f ₄ /f|<10.0.

Preferably, the optical back focus of the optical system is BFL, which satisfies the relationship with the focal length f of the optical system: |BFL/f|<1.5.

Preferably, the half-image height of the optical system is y', which satisfies the relationship with the focal length f of the optical system: |y'/f|<0.5.

Preferably, the refractive index of the first lens G1 is n1, and the refractive index of the first lens G1 satisfies the relationship: 1.8<n1<2.1.

Preferably, the refractive index of the second lens G2 is n2, and the refractive index of the third lens G3 is n3, both of which satisfy the relationship: 1.65<n2<1.9; 1.65<n3<1.9; the Abbe coefficient of the second lens G2 is v2, and the Abbe coefficient of the third lens G3 is v3, both of which satisfy the relational expressions: 20<v2<35; 40<v3<60.

Preferably, the eighth lens G8 and the ninth lens G9 form a third cemented lens U3.

Preferably, the refractive index of the eighth lens G8 is n8, and the refractive index of the ninth lens G9 is n9, both of which satisfy the relational formula: 1.7<n8<2.1; 1.7<n9<2.1; the Abbe coefficient of the eighth lens G8 is v8, and the Abbe coefficient of the ninth lens G9 is v9, both of which satisfy the relational expressions: 40<v8<60; 20<v9<35.

Preferably, the fourth lens G4 and the fifth lens G5 form the first cemented lens U1, the sixth lens G6 and the seventh lens G7 form the second cemented lens U2, the focal length of the first cemented lens U1 is f _U1 , and the second The focal length of the cemented lens U2 is f _U2 , the ratio of the focal length of the first cemented lens U1 to the focal length of the middle lens group 2 satisfies the relation: 0.9<|f _U1 /f ₂ |<2.0, the focal length of the second cemented lens U2 and the middle lens group The ratio of the focal length of the lens group 2 satisfies the relationship: 3.0<|f _U2 /f ₂ |<6.0.

Preferably, the focal length of the tenth lens G10 is f _G10 , the focal length of the eleventh lens G11 is f _G11 , the ratio of the focal length of the tenth lens G10 to the focal length of the focusing group 4 and the ratio of the focal length of the eleventh lens G11 to the focusing group 4 The ratio of the focal length, while satisfying the relationship: 0.05<|f _G10 /f ₄ |<0.2;0.05<|f _G11 /f ₄ |<0.2.

Preferably, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7, the eighth lens G8, the ninth lens G9, the tenth lens Both the lens G10 and the eleventh lens G11 are spherical mirrors.

Specific optical system data are as follows:

surface radius thickness refraction G1 front surface 61.5 5.8 2.0 G1 posterior surface 239.1 0.1 G2 front surface 40.6 3.6 1.7 G2 back surface 49.4 4.2 G3 front surface 586.8 2.2 1.8 G3 back surface 28.7 21.3 U1 front surface 259.9 2.2 1.7 U1 glued surface 34.0 11.0 1.7 U1 back surface -119.8 0.1 U2 front surface 53.7 6.1 1.9 U2 glued surface -32.0 3.5 1.8 U2 rear surface 45.6 5.1 aperture Infinity 11.5 U3 front surface -177.3 4.4 1.7 U3 glued surface -23.2 3.3 2.0 U3 back surface -43.5 16.8 G10 front table 109.4 4.8 1.8 G10 rear table -109.4 4.9 G11 front table -66.9 2.2 1.6 G11 rear table 66.9 35.8 Image surface Infinity

The focal length f of the optical system in the embodiment is 75mm, the maximum aperture is F#=2.8, the focal length f 1 of the front lens group ₁ =-206.1mm, the focal length f 2 of the middle lens group ₂ =76.2mm, and the focal length f of the rear lens group 3 ₃ =114.1mm, focal length f ₄ of focusing group 4 =-623.8mm, focal length f U1 of the first cemented lens group _U1 =103.1mm, focal length f _{U2 of the second cemented lens group U2} =377.2mm, tenth lens G10 The focal length f _G10 =65.8mm, the focal length f _G11 of the eleventh lens G11 =−53.3mm, the optical back focus BFL=35.8mm, and the half-image height y′=22mm.

Each relationship:

|f ₁ /f|=2.7; |f ₂ /f|=1.0; |f ₃ /f|=1.5; |f ₄ /f|=8.3

|BFL/f|=0.5; |y'/f|=0.3; |f _U1 /f ₂ |=1.3; |f _U2 /f ₂ |=4.9;

|f _G10 /f ₄ | = 0.1; |f _G11 /f ₄ | = 0.08.

satisfy the relation:

1.5<|f ₁ /f|<4.0;0.5<|f ₂ /f|<1.5;1.0<|f ₃ /f|<2.0;5.0<|f ₄ /f|<10.0;

|BFL/f|<1.5;|y'/f|<0.5;0.9<|f _U1 /f ₂ |<2.0;3.0<|f _U2 /f ₂ |<6.0;

0.05<|f _G10 /f ₄ |<0.2;0.05<|f _G11 /f ₄ |<0.2.

Figure 3 shows the transfer function curve. The MTF value of the full field of view at 140lp/mm is >0.3, and the theoretical resolution accuracy can reach 3.5 microns, realizing high-resolution imaging of the optical system.

Figure 4 shows the optical distortion curve, the maximum optical distortion in the whole field of view is less than 0.03%;

Through the above structure, the optical system of a low-distortion lens with a focal length of 75mm, high pixels and wide working distance is realized, and the maximum imaging surface is Its resolution can reach 140lp/mm, the highest pixel can reach 70 million pixels, and the optical distortion of the whole field of view is less than 0.03%. Different application requirements, and its clear aperture can also be flexibly adjusted.

According to the disclosure and teaching of the above specification, those skilled in the art to which the present utility model belongs can also change and modify the above embodiment. Therefore, the utility model is not limited to the above specific implementation manners, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the utility model shall belong to the protection scope of the utility model. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present utility model.

Claims (10)

1. a kind of low distortion camera lens, it is characterised in that: including be arranged successively along optical axis from object side to image side front lens group (1), Middle lens group (2), diaphragm (5), rear lens group (3) and focusing group (4)；

The front lens group (1) includes the with positive light coke and bent moon structure being arranged successively along optical axis from object side to image side One lens G1, the second lens G2 with positive light coke and bent moon structure and the third with negative power and bent moon structure Lens G3；

The middle lens group (2) includes the with negative power and bent moon structure being arranged successively along optical axis from object side to image side Four lens G4, the 5th lens G5 with positive light coke and biconvex structure, the 6th lens with positive light coke and biconvex structure G6 and the 7th lens G7 with negative power and double-concave structure；

The rear lens group (3) includes the with positive light coke and bent moon structure being arranged successively along optical axis from object side to image side Eight lens G8 and the 9th lens G9 with negative power and bent moon structure；

The focusing group (4) includes the ten with positive light coke and biconvex structure being arranged successively along optical axis from object side to image side Lens G10 and the 11st lens G11 with negative power and double-concave structure；

The focal length of optical system is f, and the focal length of the front lens group (1) is f₁, the focal length of the middle lens group (2) is f₂, described The focal length of rear lens group (3) is f₃, the focal length of the focusing group (4) is f₄, meet relational expression respectively: 1.5 < | f₁/f|<4.0； 0.5<|f₂/f|<1.5；1.0<|f₃/f|<2.0；5.0<|f₄/f|<10.0。

2. a kind of low distortion camera lens as described in claim 1, it is characterised in that: the optics rear cut-off distance of the optical system is The focal length f of BFL, it and the optical system meet relational expression: | BFL/f | < 1.5.

3. a kind of low distortion camera lens as claimed in claim 1 or 2, it is characterised in that: half image height of the optical system is The focal length f of y ', it and the optical system meet relational expression: | y '/f | < 0.5.

4. a kind of low distortion camera lens as described in claim 1, it is characterised in that: the refractive index of the first lens G1 is n1, The refractive index of the first lens G1 meets relational expression: 1.8 < n1 < 2.1.

5. a kind of low distortion camera lens as described in claim 1, it is characterised in that: the refractive index of the second lens G2 is n2, The refractive index of the third lens G3 is n3, and the two meets relational expression: 1.65 < n2 < 1.9 simultaneously；1.65 < n3 < 1.9；Institute The Abbe number for stating the second lens G2 is v2, and the Abbe number of the third lens G3 is v3, and the two meets relational expression respectively: 20 < v2 < 35；40 < v3 < 60.

6. a kind of low distortion camera lens as claimed in claim 1 or 2, it is characterised in that: the 4th lens G4 and the described 5th Lens G5 group is shaped to the first balsaming lens U1, the 6th lens G6 and the 7th lens G7 group is shaped to the second gluing thoroughly The focal length of mirror U2, the first balsaming lens U1 are f_U1, the focal length of the second balsaming lens U2 is f_U2, described first is glued The ratio of the focal length of lens U1 and the focal length of the middle lens group (2) meets relational expression: 0.9 < | f _U1/ f₂| < 2.0, it is described The ratio of the focal length of second balsaming lens U2 and the focal length of the middle lens group (2) meets relational expression: 3.0 < | f _U2/ f₂| < 6.0。

7. a kind of low distortion camera lens as claimed in claim 1 or 2, it is characterised in that: the focal length of the tenth lens G10 is f_G10, the focal length of the 11st lens G11 is f_G11, the focal length of the focal length of the tenth lens G10 and the focusing group (4) The ratio of ratio and the 11st lens G11 and the focal length of the focusing group (4), while meeting relational expression: 0.05 < | f _G10/ f₄| < 0.2；0.05 < | f _G11/ f₄| < 0.2.

8. a kind of low distortion camera lens as described in claim 1, it is characterised in that: the 8th lens G8 and the 9th lens G9 group is shaped to third balsaming lens U3.

9. a kind of low distortion camera lens as claimed in claim 1 or 8, it is characterised in that: the refractive index of the 8th lens G8 is The refractive index of n8, the 9th lens G9 are n9, and the two meets relational expression: 1.7 < n8 < 2.1 simultaneously；1.7 < n9 < 2.1；Institute The Abbe number for stating the 8th lens G8 is v8, and the Abbe number of the 9th lens G9 is v9, and the two meets relational expression respectively: 40 < v8 < 60；20 < v9 < 35.

10. a kind of low distortion camera lens as described in claim 1, it is characterised in that: the first lens G1, second lens G2, the third lens G3, the 4th lens G4, the 5th lens G5, the 6th lens G6, the 7th lens G7, the 8th lens G8, the 9th lens G9, the tenth lens G10 and the 11st lens G11 are spherical surface Mirror.