Multi-standoff inner wall detection industrial lens

Abstract

The application discloses a multi- object distance inner wall detection industrial lens, which comprises a diaphragm, a first lens group, a second lens group, a third lens group and a fourth lens group arranged in sequence from an object side to an image side, wherein the first lens group comprises first to eighth lenses arranged in sequence, the third, fourth and fifth lenses form a three-cemented lens, the seventh and eighth lenses form a first double-cemented lens, the second lens group comprises ninth to eleventh lenses arranged in sequence, the tenth and eleventh lenses form a second double-cemented lens, the third lens group comprises twelfth and thirteenth lenses arranged in sequence, and the twelfth and thirteenth lenses form a third double-cemented lens. Compared with conventional focus adjustment, the floating focus technology can greatly reduce chromatic aberration from near and far distances, and good image quality can be obtained at different working object distances.

Description

Technical Field

[0001] This invention relates to the field of machine vision, and in particular to an industrial lens for multi-object distance inner wall detection. Background Technology

[0002] In recent years, with the development of the automation industry, machine vision has achieved rapid growth. The application fields of industrial lenses are becoming more and more extensive, and the market demand for the image quality of lenses is also getting higher and higher. Using fewer cameras to photograph every side of an object is a common requirement in the current machine vision market, and it is necessary to have good imaging effects at different working object distances.

[0003] Multi-distance internal wall inspection industrial lenses are used to simultaneously image the bottom and inner side of objects with holes, especially for the inspection of cylindrical or perforated objects such as medicine bottles, bottle caps, nuts, and mechanical parts. However, most industrial lenses on the market can hardly fully present the inner wall of the hole of the object being tested through a single shot, and their imaging effect varies greatly under different working distances. Therefore, a multi-distance internal wall inspection industrial lens is proposed to address the above problems. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] An industrial lens for multi-object distance inner wall inspection includes an aperture, a first group of lenses, a second group of lenses, a third group of lenses, and a fourth group of lenses arranged sequentially from the object side to the image side. The first group of lenses includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially. The third lens, the fourth lens, and the fifth lens form a cemented triplet lens, and the seventh lens and the eighth lens form a first cemented doublet lens.

[0006] The second group of lenses includes a ninth lens, a tenth lens and an eleventh lens arranged in sequence, with the tenth lens and the eleventh lens forming a second cemented doublet lens.

[0007] The third group of lenses includes a twelfth lens and a thirteenth lens arranged in sequence, and the twelfth lens and the thirteenth lens form a third cemented doublet lens;

[0008] The fourth group of lenses includes the fourteenth and fifteenth lenses arranged sequentially. The first, second, ninth, tenth, thirteenth and fourteenth lenses have positive optical power and a meniscus. The fifth, sixth and seventh lenses have positive optical power and a biconvex structure. The fourth and eighth lenses have negative optical power and a biconcave structure. The third, eleventh, twelfth and fifteenth lenses have negative optical power and a meniscus.

[0009] Preferably, the air gap between the first lens and the second lens is 0.1 mm, the air gap between the second lens and the third lens is 0.1 mm, the third lens, the fourth lens, and the fifth lens form a cemented triplet lens, the air gap between the fifth lens and the sixth lens is 0.2 mm, the air gap between the sixth lens and the seventh lens is 0.22 mm, the seventh lens and the eighth lens form a first cemented doublet lens, the air gap between the eighth lens and the ninth lens is 56 mm, the air gap between the ninth lens and the tenth lens is 0.1 mm, the tenth lens and the eleventh lens form a second cemented doublet lens, the air gap between the eleventh lens and the twelfth lens is 25 mm, the twelfth lens and the thirteenth lens form a third cemented doublet lens, the air gap between the thirteenth lens and the fourteenth lens is 3.2 mm, and the air gap between the fourteenth lens and the fifteenth lens is 0.1 mm.

[0010] Preferably, when the working object distance changes, the air gap between the thirteenth lens and the fourteenth lens is adjusted for focusing. When the working object distance is 13mm, the air gap between the thirteenth lens and the fourteenth lens is 3.2mm; when the working object distance is 50mm, the air gap between the thirteenth lens and the fourteenth lens is 4mm; and when the working object distance is 8mm, the air gap between the thirteenth lens and the fourteenth lens is 2.4mm.

[0011] Preferably, the focal length of the lens's optical system is set to f, and the system focal lengths shared by the first group lens, the second group lens, the third group lens, and the fourth group lens are fA, fB, fC, and fD, respectively, where f satisfies the following condition: 6mm. <fA <10mm;26mm<fB<40mm;-20mm<fC<-150mm;10mm<fD<20mm。

[0012] Compared with the prior art, the beneficial effects of the present invention are: (1) The multi-object distance inner wall detection industrial lens of the present invention has the characteristics of non-contact and no need to place the lens inside the hole.

[0013] The multi-object distance inner wall inspection industrial lens of this invention adopts floating focus technology. Compared with conventional back focus adjustment, it can significantly reduce chromatic aberration from near to far distances and obtain better image quality at different working object distances.

[0014] The present invention provides an industrial lens for multi-object distance inner wall detection. By using a combination of multiple lens groups with matching positive and negative optical power, the lens has a reasonable structure and solves the problems of insufficient clarity, small field of view, and complex structure of existing industrial lenses. Attached Figure Description

[0015] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the lens optical path structure of the present invention;

[0017] Figure 2 For the present invention Figure 1 Schematic diagram of structure A in the middle;

[0018] Figure 3 For the present invention Figure 1 Schematic diagram of structure B in the middle;

[0019] Figure 4 For the present invention Figure 1 Schematic diagram of the C-structure;

[0020] Figure 5 For the present invention Figure 1 Schematic diagram of the D-structure;

[0021] Figure 6 This is the MTF curve of the present invention at a workpiece distance of 13mm;

[0022] Figure 7 This is a field curvature and distortion diagram of the present invention at a working distance of 13mm.

[0023] The reference numerals in the diagram are as follows: aperture S, first lens group A, second lens group B, third lens group C, fourth lens group D, first lens G1, second lens G2, third lens G3, fourth lens G4, fifth lens G5, sixth lens G6, seventh lens G7, eighth lens G8, ninth lens G9, tenth lens G10, eleventh lens G11, twelfth lens G12, thirteenth lens G13, fourteenth lens G14, fifteenth lens G15, cemented triplet lens U1, first cemented doublet lens U2, second cemented doublet lens U3, third cemented doublet lens U4. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Please see Figure 1-7 This invention provides an embodiment of an industrial lens for multi-object distance inner wall inspection, comprising an aperture stop S, a first lens group A, a second lens group B, a third lens group C, and a fourth lens group D arranged sequentially from the object side to the image side. The first lens group A includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, and an eighth lens G8 arranged sequentially. The third lens G3, the fourth lens G4, and the fifth lens G5 form a cemented triplet lens U1, and the seventh lens G7 and the eighth lens G8 form a first cemented doublet lens U2. The second lens group B includes a ninth lens G9, a tenth lens G10, and an eleventh lens G11 arranged sequentially. The tenth lens G10 and the eleventh lens G11 form a second cemented doublet lens U3. The third lens group... C includes a twelfth lens G12 and a thirteenth lens G13 arranged sequentially. The twelfth lens G12 and the thirteenth lens G13 form a third cemented doublet lens U4. The fourth group of lenses D includes a fourteenth lens G14 and a fifteenth lens G15 arranged sequentially. The first lens G1, the second lens G2, the ninth lens G9, the tenth lens G10, the thirteenth lens G13 and the fourteenth lens G14 have positive optical power and a meniscus. The fifth lens G5, the sixth lens G6 and the seventh lens G7 have positive optical power and a biconvex structure. The fourth lens G4 and the eighth lens G8 have negative optical power and a biconcave structure. The third lens G3, the eleventh lens G11, the twelfth lens G12 and the fifteenth lens G15 have negative optical power and a meniscus. The third lens G3 and the fourth lens G4 have negative optical power and a biconcave structure.

[0027] The air gap between the first lens G1 and the second lens G2 is 0.1 mm, the air gap between the second lens G2 and the third lens G3 is 0.1 mm. The third lens G3, the fourth lens G4 and the fifth lens G5 form a triple cemented lens U1. The air gap between the fifth lens G5 and the sixth lens G6 is 0.2 mm, the air gap between the sixth lens G6 and the seventh lens G7 is 0.22 mm. The seventh lens G7 and the eighth lens G8 form a first doublet lens U2. The air gap between the eighth lens G8 and the ninth lens G9 is 56 mm, the air gap between the ninth lens G9 and the tenth lens G10 is 0.1 mm. The tenth lens G10 and the eleventh lens G11 form a second doublet lens U3. The air gap between the eleventh lens G11 and the twelfth lens G12 is 25 mm. The twelfth lens G12 and the thirteenth lens G13 form a third doublet lens U4. The air gap between the thirteenth lens G13 and the fourteenth lens G14 is 3.2 mm, and the air gap between the fourteenth lens G14 and the fifteenth lens G15 is 0.1 mm.

[0028] When the object distance changes, the air gap between the thirteenth lens G13 and the fourteenth lens G14 is adjusted for focusing. When the object distance is 13 mm, the air gap between the thirteenth lens G13 and the fourteenth lens G14 is 3.2 mm; when the object distance is 50 mm, the air gap between the thirteenth lens G13 and the fourteenth lens G14 is 4 mm; when the object distance is 8 mm, the air gap between the thirteenth lens G13 and the fourteenth lens G14 is 2.4 mm.

[0029] The focal length of the optical system of the lens is set as f, and the system focal lengths shared by the first group of lenses A, the second group of lenses B, the third group of lenses C, and the fourth group of lenses D are fA, fB, fC, and fD respectively, where f satisfies the following conditions: 6 mm < fA < 10 mm; 26 mm < fB < 40 mm; -20 mm < fC < -150 mm; 10 mm < fD < 20 mm. By reasonably distributing the optical power of the optical system according to the above ratio, the aberrations of the optical system in the wavelength range of 400 - 700 nm are reasonably corrected and balanced.

[0030] As can be seen from the above, by adopting the floating focusing technology in group D, the chromatic aberration can be greatly reduced from near to far distances, making the imaging effect consistent. By reasonably distributing the focal lengths of each lens, the depth of field of the imaging system is large and the clarity is high. Through the optical system composed of the above lenses, the inner wall of the hole of the measured object can be completely presented only by single shooting, reducing costs and improving the detection efficiency. The optical back focus of the lens is large, and it can be used in cooperation with cameras with various interfaces.

[0031] The parameters of each lens are shown in the following table:

[0032]

[0033] The technical specifications of the optical system provided in this embodiment are as follows:

[0034] (1) Focal length: f = -3.46 mm;

[0035] (2) Relative aperture: D / f = 1: 7.69;

[0036] (3) Field of view: 2w ≥ 100°;

[0037] (4) Depth of field: ≥4mm;

[0038] (5) The total length of the optical path ∑=130mm, and the optical back intercept L'≥11mm;

[0039] (6) Applicable spectral range: 400nm~700nm.

[0040] In summary, the multi-object distance inner wall inspection industrial lens provided by this invention has the characteristics of being non-contact and not requiring the lens to be placed inside the hole. It adopts floating focusing technology, which can significantly reduce chromatic aberration from near to far distances, and can obtain good image quality and large depth of field at different working object distances.

[0041] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An industrial lens for multi-object distance inner wall inspection, characterized in that: It includes an aperture stop (S), a first group of lenses (A), a second group of lenses (B), a third group of lenses (C), and a fourth group of lenses (D) arranged sequentially from the object side to the image side. The first group of lenses (A) includes a first lens (G1), a second lens (G2), a third lens (G3), a fourth lens (G4), a fifth lens (G5), a sixth lens (G6), a seventh lens (G7), and an eighth lens (G8) arranged sequentially. The third lens (G3), the fourth lens (G4), and the fifth lens (G5) form a cemented triplet lens (U1), and the seventh lens (G7) and the eighth lens (G8) form a first cemented doublet lens (U2). The second group of lenses (B) includes a ninth lens (G9), a tenth lens (G10) and an eleventh lens (G11) arranged in sequence, wherein the tenth lens (G10) and the eleventh lens (G11) form a second cemented doublet lens (U3); The third group of lenses (C) includes a twelfth lens (G12) and a thirteenth lens (G13) arranged in sequence, and the twelfth lens (G12) and the thirteenth lens (G13) form a third cemented doublet lens (U4); The fourth group of lenses (D) includes a fourteenth lens (G14) and a fifteenth lens (G15) arranged sequentially. The first lens (G1), the second lens (G2), the ninth lens (G9), the tenth lens (G10), the thirteenth lens (G13), and the fourteenth lens (G14) have positive optical power and a meniscus. The fifth lens (G5), the sixth lens (G6), and the seventh lens (G7) have positive optical power and a biconvex structure. The fourth lens (G4) and the eighth lens (G8) have negative optical power and a biconcave structure. The third lens (G3), the eleventh lens (G11), the twelfth lens (G12), and the fifteenth lens (G15) have negative optical power and a meniscus.

2. The industrial lens for multi-object distance inner wall detection according to claim 1, characterized in that: The air gap between the first lens (G1) and the second lens (G2) is 0.1 mm, the air gap between the second lens (G2) and the third lens (G3) is 0.1 mm, the third lens (G3), the fourth lens (G4), and the fifth lens (G5) form a cemented triplet lens (U1), the air gap between the fifth lens (G5) and the sixth lens (G6) is 0.2 mm, the air gap between the sixth lens (G6) and the seventh lens (G7) is 0.22 mm, the seventh lens (G7) and the eighth lens (G8) form a first cemented doublet lens (U2), and the air gap between the eighth lens (G8) and the ninth lens (G9) is... The air gap is 56mm. The air gap between the ninth lens (G9) and the tenth lens (G10) is 0.1mm. The tenth lens (G10) and the eleventh lens (G11) form the second cemented doublet (U3). The air gap between the eleventh lens (G11) and the twelfth lens (G12) is 25mm. The twelfth lens (G12) and the thirteenth lens (G13) form the third cemented doublet (U4). The air gap between the thirteenth lens (G13) and the fourteenth lens (G14) is 3.2mm. The air gap between the fourteenth lens (G14) and the fifteenth lens (G15) is 0.1mm.

3. The industrial lens for multi-object distance inner wall detection according to claim 2, characterized in that: When the working object distance changes, adjust the air gap between the thirteenth lens (G13) and the fourteenth lens (G14) for focusing. When the working object distance is 13mm, the air gap between the thirteenth lens (G13) and the fourteenth lens (G14) is 3.2mm; when the working object distance is 50mm, the air gap between the thirteenth lens (G13) and the fourteenth lens (G14) is 4mm; when the working object distance is 8mm, the air gap between the thirteenth lens (G13) and the fourteenth lens (G14) is 2.4mm.

4. The industrial lens for multi-object distance inner wall detection according to claim 3, characterized in that: Let the focal length of the lens's optical system be f. The system focal lengths shared by the first group lens (A), the second group lens (B), the third group lens (C), and the fourth group lens (D) are fA, fB, fC, and fD, respectively, where f satisfies the following condition: 6mm. <fA <10mm;26mm<fB<40mm;-20mm<fC<-150mm;10mm<fD<20mm。

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