Optical system and industrial lens

Abstract

The application discloses an optical system and an industrial lens, wherein the optical system comprises a front group lens and a rear group lens; the front group lens comprises, from the object side to the image side, a biconvex positive lens L1, a biconvex positive lens L2, a biconcave negative lens L3, a biconvex positive lens L4 and a biconcave negative lens L5, wherein the biconvex positive lens L1 and the biconvex positive lens L2 are arranged at intervals; the rear group lens comprises, from the object side to the image side, a meniscus negative lens L6, a meniscus positive lens L7 and a biconvex positive lens L8, wherein the concave surface of the meniscus negative lens L6 faces the object side, and the concave surface of the meniscus positive lens L7 faces the object side; and a diaphragm AS is arranged between the biconcave negative lens L5 and the meniscus negative lens L6. Through reasonable distribution of the lenses in the optical system, when the optical system is applied to the industrial lens of the line scanning scheme, the advantages of high efficiency and low cost of the line scanning scheme can be obtained, and the requirements of high resolution and low distortion of the line scanning scheme can be met.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and in particular to an optical system and an industrial lens. Background Technology

[0002] The demand for inspection in the industrial sector is booming, which puts increasingly higher demands on industrial lenses in the field of machine vision, especially in the semiconductor industry, where the imaging performance directly determines the inspection efficiency of automated production lines.

[0003] When inspecting large-size products, area scan camera solutions are inefficient, and multi-area scan camera array solutions are too expensive. Line scan solutions have become the best choice. However, there are no industrial lenses and optical systems suitable for line scan solutions in the current technology. Using existing industrial lenses inevitably leads to problems such as insufficient resolution and large distortion.

[0004] Therefore, it is necessary to propose a brand-new optical system and industrial lens solution to achieve high detection efficiency and low cost of line scanning while possessing the advantages of high resolution and low distortion. Summary of the Invention

[0005] The main objective of this invention is to propose an optical system and industrial lens that aims to solve the problems of high cost, low detection efficiency, insufficient resolution, and large distortion in existing industrial lenses and optical systems.

[0006] To achieve the above objectives, the present invention proposes an optical system comprising:

[0007] The front lens group includes a biconvex positive lens L1, a biconvex positive lens L2, a biconcave negative lens L3, a biconvex positive lens L4, and a biconcave negative lens L5 arranged sequentially from the object side to the image side, wherein the biconvex positive lens L1 and the biconvex positive lens L2 are spaced apart.

[0008] The rear lens group includes a meniscus negative lens L6, a meniscus positive lens L7, and a biconvex positive lens L8 arranged sequentially from the object side to the image side. The concave surface of the meniscus negative lens L6 faces the object side, and the concave surface of the meniscus positive lens L7 faces the object side. An aperture stop AS is provided between the biconvex negative lens L5 and the meniscus negative lens L6.

[0009] In one embodiment, the biconvex positive lens L2 and the biconcave negative lens L3 are bonded together to form a first cemented group U1, the biconvex positive lens L4 and the biconcave negative lens L5 are bonded together to form a second cemented group U2, and the meniscus negative lens L6 and the meniscus positive lens L7 are bonded together to form a third cemented group U3.

[0010] In one embodiment, the aperture AS is a biconvex aperture AS, and one convex surface of the aperture AS is in contact with the concave surface of the biconcave negative lens L5 facing the image side, and the other convex surface of the aperture AS is in contact with the concave surface of the meniscus negative lens L6 facing the object side.

[0011] In one embodiment, the biconvex positive lens L1 has a thickness of 20 mm, a front surface radius of 218.560 mm, a rear surface radius of -1430.000 mm, and a refractive index of 1.762.

[0012] The radius of the first bonding surface of the first cemented assembly U1 is 137.300 mm, the thickness of the biconvex positive lens L2 is 11.300 mm, the refractive index is 1.595, the radius of the second bonding surface of the first cemented assembly U1 is -98.950 mm, the thickness of the biconcave negative lens L3 is 4.300 mm, the refractive index is 1.689, and the radius of the rear surface of the first cemented assembly U1 is 56.040 mm.

[0013] The radius of the first bonding surface of the second cemented assembly U2 is 62.175 mm, the thickness of the biconvex positive lens L4 is 18.700 mm, and the refractive index is 1.678. The radius of the second bonding surface of the second cemented assembly U2 is -47.760 mm, the thickness of the biconcave negative lens L5 is 8.150 mm, and the refractive index is 1.613. The radius of the rear surface of the second cemented assembly U2 is 89.160 mm, and the thickness of the aperture AS is 9.998 mm.

[0014] The radius of the first cemented surface of the third cemented assembly U3 is -42.820 mm, the thickness of the meniscus negative lens L6 is 17.400 mm, and the refractive index is 1.743, the radius of the second cemented surface of the third cemented assembly U3 is -417.200 mm, the thickness of the meniscus positive lens L7 is 12.620 mm, and the refractive index is 1.569, and the radius of the rear surface of the third cemented assembly U3 is -61.480 mm.

[0015] The biconvex positive lens L8 has a thickness of 10.100 mm, a front surface radius of 1595.000 mm, a rear surface radius of -108.730 mm, and a refractive index of 1.749.

[0016] In one embodiment, the air distance between the biconvex positive lens L1 and the biconvex positive lens L2 is 68.458 mm; the air distance between the biconcave negative lens L3 and the biconvex positive lens L4 is 2.444 mm; the air distance between the biconcave negative lens L5 and the aperture AS is 4.955 mm; the air distance between the aperture AS and the meniscus negative lens L6 is 9.998 mm; the air distance between the meniscus positive lens L7 and the biconvex positive lens L8 is 0.409 mm; and the air distance between the biconvex positive lens L8 and the image side is 378.172 mm.

[0017] In one embodiment, the total focal length of the optical system is f, the focal length of the front lens is f1, and the focal length of the rear lens is f2, satisfying the following relationships: 1.5≤|f1 / f|≤2.0, 0.5≤|f2 / f|≤1.0.

[0018] In one embodiment, the total optical length of the optical system is TTL, and the total focal length of the optical system is f, both satisfying the following conditions: TTL / f≤2.5, specifically, TTL≤567.10mm, 235mm≤f≤236mm.

[0019] The present invention also provides an industrial lens, comprising a line scan camera, a pixel chip, and the aforementioned optical system.

[0020] In one embodiment, the pixel chip has a size of 5 μm, and the target surface size of the line scan camera is 80 mm.

[0021] In one embodiment, the maximum field of view of the industrial lens is FOV, and the principal ray angle of the industrial lens is CRA, which satisfies the following relationship: 3.5≤FOV / CRA≤4.0.

[0022] The technical solution of this invention arranges a biconvex positive lens L1, a biconvex positive lens L2, a biconcave negative lens L3, a biconvex positive lens L4, a biconcave negative lens L5, an aperture AS, a meniscus negative lens L6, a meniscus positive lens L7, and a biconvex positive lens L8 sequentially from the object side to the image side. Through the rational allocation of the positions of each lens within the optical system, low distortion is achieved while maintaining the optical performance of the optical system. Furthermore, the rational allocation of the positions of lenses with different optical powers ensures the high resolution and high definition of the optical system. By rationally allocating the lenses within the optical system, this invention enables the optical system, when applied to industrial lenses using line scanning solutions, to achieve both the high efficiency and low cost advantages of line scanning solutions while meeting the high resolution and low distortion requirements of line scanning. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of an optical system provided in an embodiment of the present invention;

[0025] Figure 2 MTF diagram of an optical system provided in an embodiment of the present invention;

[0026] Figure 3 A field curvature and distortion curve diagram of an optical system provided in an embodiment of the present invention;

[0027] Figure 4 An axial aberration curve of an optical system provided in an embodiment of the present invention;

[0028] Figure 5 The diagram shows the chromatic aberration curve of an optical system provided in an embodiment of the present invention.

[0029] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0032] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0033] When inspecting large-size products, area scan camera solutions are inefficient, and multi-area scan camera array solutions are too expensive. Line scan solutions have become the best choice. However, there are no industrial lenses and optical systems suitable for line scan solutions in the current technology. Using existing industrial lenses inevitably leads to problems such as insufficient resolution and large distortion.

[0034] To address the above problems, this invention proposes an optical system.

[0035] Please see Figure 1 The optical system of this embodiment includes a front lens group and a rear lens group. The front lens group includes a biconvex positive lens L1, a biconvex positive lens L2, a biconcave negative lens L3, a biconvex positive lens L4, and a biconcave negative lens L5 arranged sequentially from the object side to the image side, wherein the biconvex positive lens L1 and the biconvex positive lens L2 are spaced apart. The rear lens group includes a meniscus negative lens L6, a meniscus positive lens L7, and a biconvex positive lens L8 arranged sequentially from the object side to the image side, wherein the concave surface of the meniscus negative lens L6 faces the object side, and the concave surface of the meniscus positive lens L7 faces the object side. An aperture AS is provided between the biconcave negative lens L5 and the meniscus negative lens L6.

[0036] The technical solution of this invention arranges a biconvex positive lens L1, a biconvex positive lens L2, a biconcave negative lens L3, a biconvex positive lens L4, a biconcave negative lens L5, an aperture AS, a meniscus negative lens L6, a meniscus positive lens L7, and a biconvex positive lens L8 sequentially from the object side to the image side. Through the rational allocation of the positions of each lens within the optical system, low distortion is achieved while maintaining the optical performance of the optical system. Furthermore, the rational allocation of the positions of lenses with different optical powers ensures the high resolution and high definition of the optical system. By rationally allocating the lenses within the optical system, this invention enables the optical system, when applied to industrial lenses using line scanning solutions, to achieve both the high efficiency and low cost advantages of line scanning solutions while meeting the high resolution and low distortion requirements of line scanning. Meanwhile, the present invention uses conventional structure lenses (biconvex positive lens, biconcave negative lens, meniscus lens), which have high manufacturing maturity and do not require special complex aspherical lenses or composite lenses, greatly reducing costs and manufacturing difficulty. While achieving high performance, it also meets the needs of industrial mass production, making the cost of the optical system much lower than that of multi-faceted camera array solutions.

[0037] In one embodiment, a biconvex positive lens L2 and a biconcave negative lens L3 are bonded together to form a first cemented group U1, a biconvex positive lens L4 and a biconcave negative lens L5 are bonded together to form a second cemented group U2, and a meniscus negative lens L6 and a meniscus positive lens L7 are bonded together to form a third cemented group U3.

[0038] By employing three sets of adhesive groups, chromatic aberration is suppressed and its accumulation is reduced, thereby optimizing optical performance, reducing the overall imaging chromatic aberration of the optical system, achieving an achromatic aberration effect, and thus enabling the entire optical system to obtain high-quality imaging capabilities with low chromatic aberration, high definition, and suitability for line scanning schemes.

[0039] In one embodiment, the aperture AS is a biconvex aperture AS, and one side of the convex surface of the aperture AS is in contact with the concave surface of the biconcave negative lens L5 facing the image side, and the other side of the convex surface of the aperture AS is in contact with the concave surface of the meniscus negative lens L6 facing the object side.

[0040] By bonding the biconvex stop AS with the biconcave negative lens L5 and the meniscus negative lens L6 respectively, a structure with continuous curvature and compound optical effect is formed, which improves the uniformity of light and helps to improve the overall optical performance of the optical system.

[0041] In one embodiment, the biconvex positive lens L1 has a thickness of 20 mm, a front surface radius of 218.560 mm, a rear surface radius of -1430.000 mm, and a refractive index of 1.762.

[0042] The radius of the first cemented surface of the first cemented assembly U1 is 137.300 mm, the thickness of the biconvex positive lens L2 is 11.300 mm, the refractive index is 1.595, the radius of the second cemented surface of the first cemented assembly U1 is -98.950 mm, the thickness of the biconcave negative lens L3 is 4.300 mm, the refractive index is 1.689, and the radius of the rear surface of the first cemented assembly U1 is 56.040 mm.

[0043] The radius of the first cemented surface of the second cemented assembly U2 is 62.175 mm, the thickness of the biconvex positive lens L4 is 18.700 mm, the refractive index is 1.678, the radius of the second cemented surface of the second cemented assembly U2 is -47.760 mm, the thickness of the biconcave negative lens L5 is 8.150 mm, the refractive index is 1.613, the radius of the rear surface of the second cemented assembly U2 is 89.160 mm, and the thickness of the aperture AS is 9.998 mm.

[0044] The radius of the first cemented surface of the third cemented assembly U3 is -42.820 mm, the thickness of the meniscus negative lens L6 is 17.400 mm, and the refractive index is 1.743. The radius of the second cemented surface of the third cemented assembly U3 is -417.200 mm, the thickness of the meniscus positive lens L7 is 12.620 mm, and the refractive index is 1.569. The radius of the rear surface of the third cemented assembly U3 is -61.480 mm.

[0045] The thickness of the biconvex positive lens L8 is 10.100mm, its front surface radius is 1595.000mm, its rear surface radius is -108.730mm, and its refractive index is 1.749.

[0046] Understandably, the above-mentioned radii are radii of curvature. The radius of curvature of the convex surface facing the object side is positive, and the radius of curvature of the convex surface facing the image side is negative.

[0047] In one embodiment, the air distance between the biconvex positive lens L1 and the biconvex positive lens L2 is 68.458 mm; the air distance between the biconcave negative lens L3 and the biconvex positive lens L4 is 2.444 mm; the air distance between the biconcave negative lens L5 and the aperture AS is 4.955 mm; the air distance between the aperture AS and the meniscus negative lens L6 is 9.998 mm; the air distance between the meniscus positive lens L7 and the biconvex positive lens L8 is 0.409 mm; and the air distance between the biconvex positive lens L8 and the image side is 378.172 mm.

[0048] Please combine Figures 2 to 5 By using the lens settings described above, the overall imaging effect can be referenced. Figure 2 MTF chart, Figure 3 Field curvature and distortion curves Figure 4 Axial aberration curves and Figure 5The chromatic aberration curve shows that the final imaging effect of the industrial lens using the optical system in this embodiment is achieved through... Figure 2 The MTF chart evaluation shows that at 100 lp / mm, the MTF > 0.4 and is close to the diffraction limit, with the overall curve smoothly decreasing, indicating that this industrial lens has good imaging performance across the entire field of view; from Figure 3 The field curvature and distortion diagrams show that the maximum distortion of this industrial lens does not exceed 0.2%; from Figure 4 Axial aberration curves and Figure 5 The vertical axis color difference curve shows that its color difference correction is good, meeting the needs of high-precision and fast scanning in the industrial field.

[0049] In one embodiment, the total focal length of the optical system is f, the focal length of the front lens is f1, and the focal length of the rear lens is f2, satisfying the following relationships: 1.5≤|f1 / f|≤2.0, 0.5≤|f2 / f|≤1.0.

[0050] By rationally setting the ratio between the focal length of the front lens, the focal length of the rear lens, and the total focal length of the optical system, the requirement for high resolution was achieved.

[0051] In one embodiment, the total optical length of the optical system is TTL, and the total focal length of the optical system is f, both satisfying the following condition: TTL / f ≤ 2.5. Specifically, TTL ≤ 567.10 mm, 235 mm ≤ f ≤ 236 mm.

[0052] The present invention also provides an industrial lens, including a line scan camera, a pixel chip, and the aforementioned optical system. The specific structure of the optical system is as described in the above embodiments. This industrial lens combines a line scan camera and a pixel chip with the aforementioned optical system, achieving the advantages of low cost and high efficiency of a line scan camera while adapting to the optical requirements of the line scan camera. This results in the industrial lens exhibiting high resolution, low distortion, and achromatic aberration when using this optical system.

[0053] In one embodiment, the pixel chip has a size of 5 μm, and the target surface size of the line scan camera is 80 mm.

[0054] When the target surface size of the line scan camera is 80mm, it can be adapted to the inspection of more and larger products, while the 5μm pixel chip is adapted to the line scan camera with a large target surface size. By adopting the above parameters, the optical system resolution is 100 lp / mm.

[0055] In one embodiment, the maximum field of view of the industrial lens is FOV, and the principal ray angle of the industrial lens is CRA, which satisfies the following relationship: 3.5≤FOV / CRA≤4.0.

[0056] By properly setting the ratio between FOV and CRA, industrial lenses can maintain high resolution performance on high-pixel-density line scan sensors, while reducing distortion and improving linear measurement accuracy.

[0057] The above are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An optical system, characterized in that, The optical system consists of a front lens group and a rear lens group. The front lens group consists of a biconvex positive lens L1, a biconvex positive lens L2, a biconcave negative lens L3, a biconvex positive lens L4, and a biconcave negative lens L5 arranged sequentially from the object side to the image side, wherein the biconvex positive lens L1 and the biconvex positive lens L2 are spaced apart. The rear lens group comprises a meniscus negative lens L6, a meniscus positive lens L7, and a biconvex positive lens L8 arranged sequentially from the object side to the image side, wherein the concave surface of the meniscus negative lens L6 faces the object side, and the concave surface of the meniscus positive lens L7 faces the object side; an aperture AS is provided between the biconvex negative lens L5 and the meniscus negative lens L6. The biconvex positive lens L2 and the biconcave negative lens L3 are bonded together to form a first cemented group U1, the biconvex positive lens L4 and the biconcave negative lens L5 are bonded together to form a second cemented group U2, and the meniscus negative lens L6 and the meniscus positive lens L7 are bonded together to form a third cemented group U3. The biconvex positive lens L1 has a thickness of 20 mm, a front surface radius of 218.560 mm, a rear surface radius of -1430.000 mm, and a refractive index of 1.

762. The radius of the first bonding surface of the first cemented assembly U1 is 137.300 mm, the thickness of the biconvex positive lens L2 is 11.300 mm, the refractive index is 1.595, the radius of the second bonding surface of the first cemented assembly U1 is -98.950 mm, the thickness of the biconcave negative lens L3 is 4.300 mm, the refractive index is 1.689, and the radius of the rear surface of the first cemented assembly U1 is 56.040 mm. The radius of the first bonding surface of the second cemented assembly U2 is 62.175 mm, the thickness of the biconvex positive lens L4 is 18.700 mm, and the refractive index is 1.

678. The radius of the second bonding surface of the second cemented assembly U2 is -47.760 mm, the thickness of the biconcave negative lens L5 is 8.150 mm, and the refractive index is 1.

613. The radius of the rear surface of the second cemented assembly U2 is 89.160 mm, and the thickness of the aperture AS is 9.998 mm. The radius of the first cemented surface of the third cemented assembly U3 is -42.820 mm, the thickness of the meniscus negative lens L6 is 17.400 mm, and the refractive index is 1.743, the radius of the second cemented surface of the third cemented assembly U3 is -417.200 mm, the thickness of the meniscus positive lens L7 is 12.620 mm, and the refractive index is 1.569, and the radius of the rear surface of the third cemented assembly U3 is -61.480 mm. The biconvex positive lens L8 has a thickness of 10.100 mm, a front surface radius of 1595.000 mm, a rear surface radius of -108.730 mm, and a refractive index of 1.

749.

2. The optical system as described in claim 1, characterized in that, The aperture AS is a biconvex aperture AS, and one side of the convex surface of the aperture AS is in contact with the concave surface of the biconcave negative lens L5 facing the image side, and the other side of the convex surface of the aperture AS is in contact with the concave surface of the meniscus negative lens L6 facing the object side.

3. The optical system as described in any one of claims 1 to 2, characterized in that, The total focal length of the optical system is f, the focal length of the front lens is f1, and the focal length of the rear lens is f2, satisfying the following relationships: 1.5≤|f1 / f|≤2.0, 0.5≤|f2 / f|≤1.

0.

4. The optical system as described in any one of claims 1 to 2, characterized in that, The total optical length of the optical system is TTL, and the total focal length of the optical system is f, satisfying the relationship: TTL / f≤2.5, specifically, TTL≤567.10mm, 235mm≤f≤236mm.

5. An industrial lens, characterized in that, It includes a line scan camera, a pixel chip, and an optical system as described in any one of claims 1 to 4.

6. The industrial lens as described in claim 5, characterized in that, The pixel chip has a size of 5μm, and the target surface size of the line scan camera is 80mm.

7. The industrial lens as described in claim 6, characterized in that, The maximum field of view of the industrial lens is FOV, and the principal ray angle of the industrial lens is CRA, which satisfies the following relationship: 3.5≤FOV / CRA≤4.0.

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