Machine vision prime lens with focal length of 25mm

Abstract

The utility model discloses a machine vision prime lens with a focal length of 25mm, which comprises a first lens, a second lens arranged on the right side of the first lens, a third lens arranged on the right side of the second lens, a fourth lens arranged on the right side of the third lens, a diaphragm arranged between the fourth lens and the third lens, and an imaging surface arranged on the right side of the fourth lens. The focal length of the first lens is G1, the focal length of the fourth lens is G4, the focal length of the lens is f, and the optical system meets the relational expression 0.7 lt; g1 / flt; 1, 1.1, 0.4 lt; g4 / flt; and 0.6. The utility model has the advantages of novel design, simple structure, simple and convenient assembly, low cost, good optical performance, clear imaging and high resolution, and can realize the change of the object distance from 0.1 m to infinity.

Description

Technical Field

[0001] The utility model relates to the technical field of lenses, in particular to a machine vision fixed-focus lens with a focal length of 25 mm. Background Art

[0002] With the rapid development of industrial automation, fixed-focus machine vision lenses are widely used in automated production equipment. To meet the accuracy and measurement precision of automated production, inspection, and measurement, machine vision lenses must provide clear and stable imaging, low distortion, a wide working distance, and a large field of view. Traditional machine vision lenses mostly have a resolution of one million or two million pixels, which lacks clarity and has distortion greater than 1%.

[0003] The patent number is ZL 201921712856.6, and the patent name is: A Chinese utility model patent for a 25mm machine vision fixed-focus lens. It discloses the following technical solutions, specifically:

[0004] A 25mm machine vision fixed-focus lens comprises an aperture, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens, wherein the second lens is mounted on one side of the first lens, the third lens is mounted on one side of the second lens, the fourth lens is mounted on one side of the third lens, the aperture is mounted on one side of the fourth lens, the fifth lens is mounted on one side of the aperture, the sixth lens is mounted on one side of the fifth lens, the seventh lens is mounted on one side of the sixth lens, the eighth lens is mounted on one side of the seventh lens, and the ninth lens is mounted on one side of the eighth lens.

[0005] It should be pointed out that the above-mentioned lens adopts a multi-lens combination, which has a complex structure, resulting in difficulty in assembly and high production cost. Moreover, it can only achieve clear imaging within an object distance of 0.2m to infinity, and cannot achieve changes from 0.1m to infinity. Utility Model Content

[0006] The purpose of the utility model is to provide a machine vision fixed-focus lens with a focal length of 25mm to address the deficiencies of the existing technology. The machine vision fixed-focus lens with a focal length of 25mm has a novel design, a simple structure, easy assembly, low cost, good optical performance, and can achieve clear imaging and high resolution, and can realize a change in object distance from 0.1m to infinity.

[0007] In order to achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions.

[0008] A machine vision fixed-focus lens with a focal length of 25 mm includes a first lens, a second lens is installed on the right side of the first lens, a third lens is installed on the right side of the second lens, a fourth lens is installed on the right side of the third lens, an aperture is installed between the fourth lens and the third lens, an imaging surface is installed on the right side of the fourth lens, the focal length of the first lens is G1, the focal length of the fourth lens is G4, the focal length of the lens is f, and the optical system satisfies the relationship 0.7<|G1 / f|<1.1, 0.4<|G4 / f|<0.6.

[0009] The first lens, the second lens, the third lens, the fourth lens and the aperture form a movable lens group.

[0010] The lens surfaces of the first lens, the second lens, the third lens and the fourth lens are all spherical.

[0011] The aperture of the diaphragm is Adjustable.

[0012] The refractive indices of the first lens to the fourth lens are n1, n2, n3, and n4, respectively, and the Abbe numbers of the first lens to the fourth lens are v1, v2, v3, and v4, respectively, satisfying the following relationship 1.5 <n1<1.7,59.22<v1<61.07;1.5<n2<1.7,62.88<v2<64.15;1.6<n3<1.8,26.91<v3<28.32;1.6<n4<1.8,50.17<v4<52.09。

[0013] The beneficial effects of the present invention are as follows: the machine vision fixed-focus lens with a focal length of 25 mm described in the present invention includes a first lens, a second lens is installed on the right side of the first lens, a third lens is installed on the right side of the second lens, a fourth lens is installed on the right side of the third lens, and an aperture is installed between the fourth lens and the third lens, an imaging surface is installed on the right side of the fourth lens, the focal length of the first lens is G1, the focal length of the fourth lens is G4, the focal length of the lens is f, and the optical system satisfies the relationship 0.7<|G1 / f|<1.1, 0.4<|G4 / f|<0.6. The utility model uses a movable lens group composed of the first lens to the fourth lens to perform reciprocating motion along the optical axis driven by the lens mechanical structure, and the imaging surface floats and changes between 12.24mm and 19.53mm, while the remaining intervals and the optical back focal length remain unchanged. The lens can achieve a change in object distance from 0.1m to infinity; the utility model has the advantages of novel design, simple structure, easy assembly, low cost, good optical performance, clear imaging and high resolution, and can achieve a change in object distance from 0.1m to infinity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention.

[0015] Figure 1 It is a structural diagram of the utility model;

[0016] Figure 2 This is a light diagram of the present invention.

[0017] exist Figure 1 These include:

[0018] 1——first lens 2——second lens

[0019] 3 - the third lens 4 - the fourth lens

[0020] 5——Aperture 6——Imaging surface. DETAILED DESCRIPTION

[0021] The present invention will be described below in conjunction with specific implementation methods.

[0022] like Figure 1 As shown, a machine vision fixed-focus lens with a focal length of 25 mm includes a first lens 1, a second lens 2 is installed on the right side of the first lens 1, a third lens 3 is installed on the right side of the second lens 2, a fourth lens 4 is installed on the right side of the third lens 3, and an aperture 5 is installed between the fourth lens 4 and the third lens 3. An imaging surface 6 is installed on the right side of the fourth lens 4, the focal length of the first lens 1 is G1, the focal length of the fourth lens 4 is G4, the focal length of the lens is f, and the optical system satisfies the relationship 0.7<|G1 / f|<1.1, 0.4<|G4 / f|<0.6.

[0023] As preferred in this embodiment, the first lens 1 , the second lens 2 , the third lens 3 , the fourth lens 4 and the aperture 5 form a movable lens group A.

[0024] As preferred in this embodiment, the lens surfaces of the first lens 1 , the second lens 2 , the third lens 3 , and the fourth lens 4 are all spherical.

[0025] As a preferred embodiment of the present invention, the aperture of the diaphragm 5 is Adjustable.

[0026] As a preferred embodiment of the present invention, the refractive indices of the first lens 1 to the fourth lens 4 are n1, n2, n3, and n4, respectively, and the Abbe numbers of the first lens 1 to the fourth lens 4 are v1, v2, v3, and v4, respectively, satisfying the following relationship 1.5 <n1<1.7,59.22<v1<61.07;1.5<n2<1.7,62.88<v2<64.15;1.6<n3<1.8,26.91<v3<28.32,1.6<n4<1.8,50.17<v4<52.09。

[0027] The present embodiment provides a machine vision fixed-focus lens with a focal length of 25 mm. Table 1 below lists the relevant parameters of each lens, including surface type, curvature radius, thickness, refractive index of the material, and Abbe number:

[0028]

[0029] Table 1

[0030] Among them, the optical system surfaces in Table 1 are arranged in sequence according to the serial number. The surface on the object side is called the front surface of the lens, and the surface on the image side is called the back surface of the lens. Among them, S1 and S2 are the front surface and back surface of the first lens; S3 and S4 are the front surface and back surface of the second lens; S5 and S6 are the front surface and back surface of the third lens; S7 and S8 are the aperture surface; S9 are the front surface and back surface of the fourth lens. A positive curvature radius value indicates that the center of curvature is on the image side, and a negative curvature radius value indicates that the center of curvature is on the object side. The thickness value indicates the distance between the intersection of the current optical surface and the next surface on the optical axis. The refractive index indicates the refractive index of the medium between the current surface and the next surface. When the refractive index is a space, it indicates the refractive index of air.

[0031] Further explanation is needed. In the present invention, the movable lens group A composed of the first lens 1 to the fourth lens 4 is driven by the lens mechanical structure to reciprocate along the optical axis, and floats with the imaging surface 6 between 12.24mm and 19.53mm, and the remaining intervals and the optical back focal length remain unchanged. The lens can achieve a change in object distance from 0.1m to infinity; the present invention has the advantages of novel design, simple structure, easy assembly, low cost, good optical performance, clear imaging and high resolution, and a change in object distance from 0.1m to infinity.

[0032] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there may be changes in the specific implementation methods and application scope. The content of this specification should not be understood as limiting the present invention.

Claims

1. A machine vision fixed-focus lens with a focal length of 25 mm, characterized by: The optical system comprises a first lens (1), a second lens (2) is arranged on the right side of the first lens (1), a third lens (3) is arranged on the right side of the second lens (2), a fourth lens (4) is arranged on the right side of the third lens (3), a stop (5) is arranged between the fourth lens (4) and the third lens (3), an imaging surface (6) is arranged on the right side of the fourth lens (4), the focal length of the first lens (1) is G1, the focal length of the fourth lens (4) is G4, the focal length of the lens is f, and the optical system satisfies the relationship 0.7<|G1 / f|<1.1, 0.4<|G4 / f|<0.

6.

2. The machine vision fixed-focus lens with a focal length of 25 mm according to claim 1, characterized in that: The first lens (1), the second lens (2), the third lens (3), the fourth lens (4) and the aperture (5) form a movable lens group (A).

3. The machine vision fixed-focus lens with a focal length of 25 mm according to claim 1, characterized in that: The lens surfaces of the first lens (1), the second lens (2), the third lens (3) and the fourth lens (4) are all spherical.

4. The machine vision fixed-focus lens with a focal length of 25 mm according to claim 1, characterized in that: The aperture of the diaphragm (5) is adjustable between ∅6.3 mm and ∅1.1 mm.

5. The machine vision fixed-focus lens with a focal length of 25 mm according to claim 1, characterized in that: The refractive indices of the first lens (1) to the fourth lens (4) are n1, n2, n3, and n4, respectively, and the Abbe numbers of the first lens (1) to the fourth lens (4) are v1, v2, v3, and v4, respectively, satisfying the following relationship 1.5 <n1<1.7 ,59.22<v1<61.07;1.5<n2<1.7,62.88<v2<64.15;1.6<n3<1.8 ,26.91<v3<28.32,1.6<n4<1.8, 50.17<v4<52.09。

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