A high-definition industrial lens with large target surface and wide working distance

Abstract

The invention discloses a high-definition industrial lens with a large target surface and a wide working distance, comprising a first lens group G1 with a negative optical power and a second lens group G2 with a positive optical power arranged in sequence from the object plane to the image plane. When focusing, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 moves along the optical axis; the high-definition industrial lens with a large target surface and a wide working distance also meets the following conditions: 2.0≤|F1 / F2|≤6.0, ‑0.3≤f / F1≤0.1, wherein F1 is the focal length of the first lens group G1, F2 is the focal length of the second lens group G2, and f is the focal length of the optical system. The application meets the requirements of a large target surface with high pixels, a wide working distance range, good and stable analytical performance, small optical system distortion, and high imaging quality.

Description

Technical Field

[0001] The invention belongs to the technical field of optical lenses, and in particular relates to a high-definition industrial lens with a large target surface and a wide working distance. Background Art

[0002] With the continuous development of the machinery manufacturing industry, the precision requirements for large-scale machinery inspection equipment are getting higher and higher. CCD and CMOS image sensors with tens of millions of pixels are constantly emerging on the market, and the requirements for the pixels and distortion of their lenses are also getting higher and higher. Especially in some applications such as defect detection, positioning monitoring, and color sorting, the requirements for the optical distortion, applicable working distance range, and resolution of industrial lenses are relatively high; and the existing industrial lenses generally have different types or degrees of defects such as small target surface, low pixels, 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. Summary of the invention

[0003] The purpose of the present invention is to address the above-mentioned problems and propose a high-definition industrial lens with a large target surface and wide working distance, which meets the needs of high-pixel and large target surface, and has a wide working distance range, good and stable resolution performance, small optical system distortion, and high imaging quality.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] The present invention provides a high-definition industrial lens with a large target surface and a wide working distance, comprising a first lens group G1 with a negative optical power and a second lens group G2 with a positive optical power arranged in sequence from the object plane to the image plane. When focusing, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 moves along the optical axis;

[0006] The high-definition industrial lens with large target surface and wide working distance also meets the following conditions:

[0007] 2.0≤|F1 / F2|≤6.0

[0008] -0.3≤f / F1≤0.1

[0009] Wherein, F1 is the focal length of the first lens group G1, F2 is the focal length of the second lens group G2, and f is the focal length of the optical system.

[0010] Preferably, the first lens group G1 includes an optical element L having negative optical power. 11 , optical element L 11 It is the first lens close to the object plane and meets the following conditions:

[0011] 3.0≤|F 11 / F1|≤25

[0012] Among them, F 11 is the optical element L11 focal length.

[0013] Preferably, the first lens group G1 further includes an optical element L 12 , optical element L 12 It is a single lens or a cemented lens group and is located in the optical element L 11 image side.

[0014] Preferably, the first lens group G1 further includes an optical element L 13 , optical element L 13 It is a single lens or a cemented lens group and is located in the optical element L 12 image side.

[0015] Preferably, the optical element L 11 The following conditions must be met:

[0016] 1.90≤n d ≤1.98

[0017] Among them, n d is the refractive index at line d.

[0018] Preferably, the second lens group G2 includes a front lens group GF, an aperture stop ST and a rear lens group GB which are arranged in sequence from the object plane to the image plane. When focusing, the front lens group GF, the aperture stop ST and the rear lens group GB move synchronously along the optical axis.

[0019] Preferably, the rear lens group GB includes optical elements L arranged in sequence from the object plane to the image plane. 24 、Optical element L 25 and optical element L 26 , optical element L 24 It is a cemented lens group, optical element L 25 is a single lens with positive or negative optical power, the optical element L 26 It is a biconvex lens with positive optical power.

[0020] Preferably, the front lens group GF includes optical elements L arranged in sequence from the object plane to the image plane. 21 and optical element L 22 , optical element L 21 is a biconvex positive lens, and the optical element L 22 It is a single lens or a cemented lens group.

[0021] Preferably, the front lens group GF further includes an optical element L 23 , optical element L 23 It is a single lens or a cemented lens group and is located in the optical element L 22 image side.

[0022] Preferably, the high-definition industrial lens with large target surface and wide working distance also includes image plane protection glass CG.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) By controlling the focal length ratio of the first lens group G1 to the second lens group G2, and the focal length ratio of the first lens group to the optical system, the magnification of the focusing group is increased, a wider working distance can be achieved within a short stroke, the focusing speed is fast, and the post-focusing method is adopted, high-quality imaging can be achieved within a wide working distance range, meeting the requirements of 25 million pixels and 1.2-inch target surface, with high pixels, large target surface and small distortion;

[0025] 2) By controlling the focal length ratio of the first lens on the object side to the first lens group G1, the refractive index of the first lens, the position of the aperture stop ST and the focal power distribution of the second lens group G2, the optical distortion and image deformation are reduced during the imaging process, and the optical back focal length and the main ray angle are small, resulting in clearer imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the overall structure of the lens of Example 1 of the present application;

[0027] Figure 2 This is the MTF diagram of the lens of Example 1 of the present application when the working distance is 300 mm;

[0028] Figure 3 This is the MTF diagram of the lens in Example 1 of the present application when the working distance is 800 mm;

[0029] Figure 4 This is the MTF diagram of the lens of Example 1 of the present application when the working distance is 150 mm;

[0030] Figure 5 This is a schematic diagram of the overall structure of the lens of Example 2 of the present application;

[0031] Figure 6 This is the MTF diagram of the lens of Example 2 of the present application when the working distance is 300 mm;

[0032] Figure 7 This is the MTF diagram of the lens of Example 2 of the present application when the working distance is 800 mm;

[0033] Figure 8 This is the MTF diagram of the lens of Example 2 of the present application when the working distance is 150 mm;

[0034] Fig. 9 This is a schematic diagram of the overall structure of the lens of Example 3 of the present application;

[0035] Fig.10This is the MTF diagram of the lens in Example 3 of the present application when the working distance is 300 mm;

[0036] Fig.11 This is the MTF diagram of the lens of Example 3 of the present application when the working distance is 800 mm;

[0037] Fig.12 This is the MTF diagram of Example 3 of the present application when the lens working distance is 150 mm. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0039] The relevant symbols in this specification are defined as follows: F1 is the focal length of the first lens group G1, F2 is the focal length of the second lens group G2, f is the focal length of the optical system, F 11 is the optical element L 11 The focal length, S i is the surface number; R i is the radius of curvature; d i is the on-axis surface distance between the i-th surface and the i+1-th surface; n d is the refractive index; ν d is the Abbe number; Fno is the F number; θ is the half field angle, RED is the magnification; D(0) is the working distance, i.e., the distance from the object plane to the optical element L 11 The axial distance between the vertices of the side surface of the object surface; D(1) is the axial distance between the adjacent vertices of the first lens group G1 and the second lens group G2; D(2) is the axial distance between the adjacent vertices of the second lens group G2 and the protective glass CG; ∞ indicates that the surface is a plane. In the lens-related parameter data, the length unit is mm, and the unit will be omitted below.

[0040] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] A high-definition industrial lens with a large target surface and a wide working distance, comprising a first lens group G1 with negative optical power and a second lens group G2 with positive optical power arranged in sequence from the object plane to the image plane. When focusing, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 moves along the optical axis;

[0042] The high-definition industrial lens with large target surface and wide working distance also meets the following conditions:

[0043] 2.0≤|F1 / F2|≤6.0

[0044] -0.3≤f / F1≤0.1

[0045] Wherein, F1 is the focal length of the first lens group G1, F2 is the focal length of the second lens group G2, and f is the focal length of the optical system.

[0046] The lens of the present application includes a first lens group G1 with negative focal power and a second lens group G2 with positive focal power arranged in sequence from the object plane to the image plane, and light passes through each lens in the first lens group G1 and the second lens group G2 in sequence to form an image on the image plane IMG. By controlling the focal length ratio of the first lens group G1 to the second lens group G2 and the focal length ratio of the first lens group G1 to the optical system within the range of 2.0≤|F1 / F2|≤6.0 and -0.3≤f / F1≤0.1, the type magnification of the focusing group, i.e., the second lens group G2, is increased, a wider working distance is achieved within a short stroke, the focusing speed is fast, and a post-focusing method is adopted, i.e., the first lens group G1 is fixed, and the second lens group G2 is moved along the optical axis for focusing, high-quality imaging can be achieved within a wide working distance range, meeting the requirements of 25 million pixels and a 1.2-inch target surface, the optical back focal length, the main light angle and the distortion change are small, and the imaging is clearer.

[0047] In one embodiment, the first lens group G1 includes an optical element L having negative optical power. 11 , optical element L 11 It is the first lens close to the object plane and meets the following conditions:

[0048] 3.0≤|F 11 / F1|≤25

[0049] Among them, F 11 is the optical element L 11 focal length.

[0050] Among them, L in the first lens group G1 11 The focal length ratio of the optical element and the first lens group G1 is controlled to be 3.0≤|F 11 In the range of / F1|≤25, while shortening the total optical length of the lens, it also ensures that the astigmatism and distortion are small under the large target surface, so that the lens has good off-axis field of view imaging quality.

[0051] In one embodiment, the first lens group G1 further includes an optical element L 12 , optical element L 12 It is a single lens or a cemented lens group and is located in the optical element L 11 image side.

[0052] Among them, through the optical element L 12 Realize the coordination of different optical powers, adjust the magnification, and correct various aberrations.

[0053] In one embodiment, the first lens group G1 further includes an optical element L 13 , optical element L 13 It is a single lens or a cemented lens group and is located in the optical element L 12 image side.

[0054] Among them, through the optical element L 13 It can further realize the coordination of different optical powers, adjust the magnification, and correct various aberrations.

[0055] It should be noted that the optical element L 12 and optical element L 13 They are all single lenses or cemented lens groups, and can be designed according to actual needs, such as lens size, processing difficulty or imaging quality, and the number of optical elements of the first lens group G1 can be increased or decreased for adjustment.

[0056] In one embodiment, the optical element L 11 The following conditions must be met:

[0057] 1.90≤n d ≤1.98

[0058] Among them, n d is the refractive index at line d.

[0059] Among them, the optical element L 11 The refractive index range is 1.90≤n d ≤1.98, which helps to increase the lens aperture and reduce spherical aberration by increasing the refractive index of the optical element material to achieve good imaging performance.

[0060] In one embodiment, the second lens group G2 includes a front lens group GF, an aperture stop ST and a rear lens group GB which are arranged in sequence from the object plane to the image plane. When focusing, the front lens group GF, the aperture stop ST and the rear lens group GB move synchronously along the optical axis.

[0061] Among them, by controlling the position of the aperture stop ST, the lens is allowed to keep the entrance pupil position consistent with the change in object distance when focusing, thereby ensuring the stability of relative illumination within a wide working distance.

[0062] In one embodiment, the rear lens group GB includes optical elements L arranged in sequence from the object plane to the image plane. 24 、Optical element L 25 and optical element L 26 , optical element L 24 It is a cemented lens group, optical element L 25 is a single lens with positive or negative optical power, the optical element L 26 It is a biconvex lens with positive optical power.

[0063] Among them, the optical element L through the cemented lens group 24 Correction of chromatic aberration after aperture stop ST and using biconvex positive lens optical element L 26 Further correction of aberrations such as coma and astigmatism and increase of the optical back intercept provide physical space for the use of large target surface lenses.

[0064] In one embodiment, the front lens group GF includes optical elements L arranged in sequence from the object plane to the image plane. 21 and optical element L 22 , optical element L 21 is a biconvex positive lens, and the optical element L 22 It is a single lens or a cemented lens group.

[0065] Among them, through the optical element L 21 and optical element L 22 It can achieve the coordination of different optical powers, adjust the magnification and correct various aberrations.

[0066] In one embodiment, the front lens group GF further includes an optical element L 23 , optical element L 23 It is a single lens or a cemented lens group and is located in the optical element L 22 image side.

[0067] Among them, through the optical element L 23 It can further realize the coordination of different optical powers, adjust the magnification, and correct various aberrations.

[0068] It should be noted that the optical element L 22 and optical element L 23 They are all single lenses or cemented lens groups, and can be designed according to actual needs, such as lens size, processing difficulty or imaging quality, and the number of optical elements of the front lens group GF can be increased or reduced for adjustment.

[0069] In one embodiment, the high-definition industrial lens with a large target surface and a wide working distance further includes an image plane protection glass CG.

[0070] Among them, the protective glass CG is used to protect the image surface from damage and extend the service life.

[0071] The lens increases the magnification of the focusing group by reasonably configuring the focal length ratio of the first lens group G1 to the second lens group G2, and the focal length ratio of the first lens group G1 to the optical system, and achieves a wider working distance within a short stroke, with a fast focusing speed and a post-focusing method. It can achieve high-quality imaging within a wide working distance range and meet the requirements of high pixels, large target surface, and low distortion; and by reasonably configuring the focal length ratio of the first lens on the object side to the first lens group G1, the first lens L 11 The refractive index, aperture stop ST position and the focal length distribution of the second lens group G2 achieve high-performance on-axis and off-axis imaging, so that it has smaller optical distortion and image deformation during the imaging process, and the optical back focal length and chief ray angle are small, and the imaging is clear.

[0072] Hereinafter, embodiments of the high-definition industrial lens with a large target surface and a wide working distance of the present application will be described in detail based on the accompanying drawings.

[0073] Embodiment 1:

[0074] like Figure 1-4 As shown, a high-definition industrial lens with a large target surface and wide working distance includes optical elements L arranged in sequence from the object plane to the image plane. 11 、Optical element L 12 、Optical element L 13 、Optical element L 21 、Optical element L 22 , aperture stop ST, optical element L 24 、Optical element L 25 、Optical element L 26 And image plane protection glass CG.

[0075] Specifically, Figure 1 As shown, L 11 is a biconcave lens, L 12 is a biconvex lens, L 13 It is a cemented lens group composed of a double concave lens and a double convex lens arranged in sequence from the object plane to the image plane. 21 is a biconvex positive lens, L 22 It is a cemented lens group composed of a negative meniscus lens and a positive meniscus lens arranged in sequence from the object plane to the image plane. 24 It is a cemented lens group composed of a negative meniscus lens and a double convex lens arranged in sequence from the object plane to the image plane. 25 is a biconcave lens, L 26 is a double convex lens, Figure 1 The middle arrow indicates that the second lens group G2 is a focusing group that can be moved along the optical axis for focusing. And |F1 / F2|=4.09, f / F1=-0.19, |F 11 / F1|=5.84, the parameters of the lens meet: f=24.97, Fno=2.75, 2θ=42°. The optical data parameters of each lens of the lens are as follows.

[0076]

[0077] In the above table, the surface number S i In this column, 0 represents the object plane, 21 (IMG) represents the image plane, and surface numbers 1 to 20 are the surfaces of each lens, aperture stop, and protective glass from the object plane to the image plane. It should be noted that the cemented surfaces of different lenses in the cemented lens group are represented as the same surface.

[0078] The focusing data parameters of this embodiment are shown in the following table.

[0079] D(0) 300 800 150 RED 0.08 0.03 0.16 f 24.97 24.8 25.3 D(1) 2.72 4.02 0.62 D(2) 8.26 6.95 10.35

[0080] Figure 2-4 As shown, the MTF diagrams of the lens of this embodiment at different working distances of 300mm, 800mm and 150mm respectively. It can be seen from the diagram that the lens of this embodiment can achieve high-quality imaging within a wide working distance range, meeting the requirements of high pixels, large target area and low distortion.

[0081] Embodiment 2:

[0082] like Figure 5-8 As shown, a high-definition industrial lens with a large target surface and wide working distance includes optical elements L arranged in sequence from the object plane to the image plane. 11 、Optical element L 12 、Optical element L 21 、Optical element L 22 , aperture stop ST, optical element L 24 、Optical element L 25 、Optical element L 26 And image plane protection glass CG.

[0083] Specifically, Figure 5 As shown, L 11 is a biconcave lens, L 12 It is a cemented lens group composed of a negative meniscus lens and a double convex lens arranged in sequence from the object plane to the image plane. 21 is a biconvex positive lens, L 22 It is a cemented lens group composed of a double convex lens and a double concave lens arranged in sequence from the object plane to the image plane. 24 It is a cemented lens group composed of a double concave lens and a double convex lens arranged in sequence from the object plane to the image plane. 25 is a plano-convex lens, L 26 is a double convex lens, Figure 5The middle arrow indicates that the second lens group G2 is a focusing group that can be moved along the optical axis for focusing. And |F1 / F2|=2.77, f / F1=-0.28, |F 11 / F1|=4.70, the parameters of the lens satisfy: f=24.75, Fno=2.8, 2θ=38°. The optical data parameters of each lens in the lens of this embodiment are shown in the following table.

[0084]

[0085]

[0086] In the above table, the surface number S i In this column, 0 represents the object plane, 19 (IMG) represents the image plane, and surface numbers 1 to 18 are the surfaces of each lens, aperture stop, and protective glass from the object plane to the image plane. It should be noted that the cemented surfaces of different lenses in the cemented lens group are represented as the same surface.

[0087] The focusing data parameters of this embodiment are shown in the following table.

[0088] D(0) 300 800 150 RED 0.08 0.03 0.16 f 24.75 24.44 25.29 D(1) 2.88 4.26 0.54 D(2) 13.04 11.66 15.38

[0089] Figure 6-8 As shown, the MTF diagrams of the lens of this embodiment at different working distances of 300mm, 800mm and 150mm respectively. It can be seen from the diagram that the lens of this embodiment can achieve high-quality imaging within a wide working distance range, meeting the requirements of high pixels, large target area and low distortion.

[0090] Embodiment 3:

[0091] like Figure 9-12 As shown, a high-definition industrial lens with a large target surface and wide working distance includes optical elements L arranged in sequence from the object plane to the image plane. 11 、Optical element L 12 、Optical element L 13 、Optical element L 21 、Optical element L 22 、Optical element L 23 , aperture stop ST, optical element L 24 、Optical element L 25 、Optical element L 26 And image plane protection glass CG.

[0092] Specifically, Fig. 9 As shown, L 11 is a biconcave lens, L 12 It is a cemented lens group composed of a double convex lens and a double concave lens arranged in sequence from the object plane to the image plane. 13 is a biconvex lens, L 21 is a biconvex positive lens, L22 is a biconvex lens, L 23 It is a cemented lens group composed of a double convex lens and a double concave lens arranged in sequence from the object plane to the image plane. 24 It is a cemented lens group composed of a double concave lens and a double convex lens arranged in sequence from the object plane to the image plane. 25 is a negative meniscus lens, L 26 is a double convex lens, Fig. 9 The middle arrow indicates that the second lens group G2 is a focusing group that can be moved along the optical axis for focusing. And |F1 / F2|=2.84, f / F1=-0.26, |F 11 / F1|=4.21, the parameters of the lens satisfy: f=25.97, Fno=4.0, 2θ=40.7°.

[0093] The optical data parameters of each lens in the lens of this embodiment are shown in the following table.

[0094]

[0095] In the above table, the surface number S i In this column, 0 represents the object plane, 23 (IMG) represents the image plane, and surface numbers 1 to 22 are the surfaces of each lens, aperture stop, and protective glass from the object plane to the image plane. It should be noted that the cemented surfaces of different lenses in the cemented lens group are represented as the same surface.

[0096] The focusing data parameters of this embodiment are shown in the following table.

[0097] D(0) 300 800 150 RED 0.08 0.03 0.17 f 25.97 25.68 26.47 D(1) 2.70 4.18 0.25 D(2) 18.37 16.90 20.83

[0098] Figure 10-12 As shown, the MTF diagrams of the lens of this embodiment at different working distances of 300mm, 800mm and 150mm respectively. It can be seen from the diagram that the lens of this embodiment can achieve high-quality imaging within a wide working distance range, meeting the requirements of high pixels, large target area and low distortion.

[0099] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The above-described embodiments only express the more specific and detailed embodiments described in this application, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of this application, which all belong to the protection scope of this application. Therefore, the protection scope of the patent in this application shall be based on the attached claims.

Claims

1. A high-definition industrial lens with a large target surface and wide working distance, characterized by: The large target surface and wide working distance high-definition industrial lens comprises a first lens group G1 with negative optical power and a second lens group G2 with positive optical power arranged in sequence from the object plane to the image plane. When focusing, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 moves along the optical axis; The high-definition industrial lens with large target surface and wide working distance also meets the following conditions: 2.0≤|F1 / F2|≤6.0 -0.3≤f / F1≤0.1 Wherein, F1 is the focal length of the first lens group G1, F2 is the focal length of the second lens group G2, and f is the focal length of the optical system; The first lens group G1 includes an optical element L having negative optical power. 11 , the optical element L 11 It is the first lens close to the object plane and meets the following conditions: 3.0≤|F 11 / F1|≤25 Among them, F 11 The optical element L 11 focal length; The second lens group G2 includes a front lens group GF, an aperture stop ST and a rear lens group GB which are sequentially arranged from the object plane to the image plane. When focusing, the front lens group GF, the aperture stop ST and the rear lens group GB move synchronously along the optical axis.

2. The high-definition industrial lens with large target surface and wide working distance as claimed in claim 1, characterized in that: The first lens group G1 further includes an optical element L 12 , the optical element L 12 It is a single lens or a cemented lens group and is located at the optical element L 11 image side.

3. The high-definition industrial lens with large target surface and wide working distance as claimed in claim 2, characterized in that: The first lens group G1 further includes an optical element L 13 , the optical element L 13 It is a single lens or a cemented lens group and is located at the optical element L 12 image side.

4. The high-definition industrial lens with a large target surface and wide working distance according to any one of claims 1 to 3, characterized in that: The optical element L 11 The following conditions must be met: 1.90≤n d ≤1.98 Among them, n d is the refractive index at line d.

5. The high-definition industrial lens with large target surface and wide working distance as claimed in claim 1, characterized in that: The rear lens group GB includes optical elements L arranged in sequence from the object plane to the image plane 24 、Optical element L 25 and optical element L 26 , the optical element L 24 The optical element L is a cemented lens group. 25 is a single lens with positive or negative optical power, the optical element L 26 It is a biconvex lens with positive optical power.

6. The high-definition industrial lens with a large target surface and wide working distance as claimed in claim 5, characterized in that: The front lens group GF includes optical elements L arranged in sequence from the object plane to the image plane. 21 and optical element L 22 , the optical element L 21 is a biconvex positive lens, the optical element L 22 It is a single lens or a cemented lens group.

7. The high-definition industrial lens with large target surface and wide working distance as claimed in claim 6, characterized in that: The front lens group GF also includes an optical element L 23 , the optical element L 23 It is a single lens or a cemented lens group and is located at the optical element L 22 image side.

8. The high-definition industrial lens with large target surface and wide working distance as claimed in claim 1, characterized in that: The large target surface and wide working distance high-definition industrial lens also includes image plane protection glass CG.

Images