Optical imaging lens and optical imaging device for collecting welding image

Abstract

The application provides an optical imaging lens and an optical imaging device for collecting a welding image. The optical imaging lens comprises, in sequence from an object side to an image side, an object side lens group, a filter and an image side lens group. The object side lens group comprises, in sequence from the object side to the image side, a first lens, a second lens and a third lens. The second lens and the third lens are cemented to form a first cemented lens. The first lens has positive refractive power, and the first cemented lens has negative refractive power. The filter is a high-pass spatial filter for filtering out a low-frequency region corresponding to welding background light, and the high-pass spatial filter is located on a stop surface of the optical imaging lens. The image side lens group comprises, in sequence from the object side to the image side, a fourth lens, a fifth lens and a sixth lens. The fourth lens and the fifth lens are cemented to form a second cemented lens. The second cemented lens has negative refractive power, and the sixth lens has positive refractive power. The optical imaging lens can effectively suppress strong background light interference and has a compact structure.

Description

Technical Field

[0001] This invention relates to optical imaging equipment, and more particularly to an optical imaging lens and optical imaging device for acquiring welding images. Background Technology

[0002] With the gradual development of welding automation and intelligent control technology, traditional visual monitoring methods are increasingly unable to meet the requirements of real-time sensing and closed-loop control of welding quality. Addressing the complex acoustic, optical, electrothermal, magnetic, noise, and high-frequency radiation phenomena during welding, the application of machine vision to automatic welding monitoring offers significant advantages, such as intuitive welding image representation and rich feature information, and can, to a certain extent, meet the process control requirements for real-time monitoring of the weld pool.

[0003] However, the welding process generates intense arc light, which can blur the image of the welding area, making it difficult to clearly capture detailed images of the weld pool and weld seam. Currently available industrial monitoring lenses struggle to effectively filter welding arc light and lack the ability to suppress strong background light, resulting in weld pool images that do not meet the requirements for further feature analysis. Furthermore, most of these industrial monitoring lenses are telecentric lenses, with large overall dimensions and long working distances, leading to interference in welding scenarios with limited monitoring space. Summary of the Invention

[0004] The purpose of this invention is to provide an optical imaging lens and optical imaging device for acquiring welding images, which can effectively suppress strong background light interference and has a compact structure.

[0005] One aspect of the present invention provides an optical imaging lens for acquiring welding images, the optical imaging lens comprising, from the object side to the image side, an object-side lens group, a filter, and an image-side lens group; wherein, both the object-side lens group and the image-side lens group have positive optical power; the object-side lens group is composed of a first lens, a second lens, and a third lens from the object side to the image side; the second lens and the third lens are cemented together to form a first cemented lens; the first lens has positive optical power, and the first cemented lens has negative optical power; the filter is a high-pass spatial filter located at the aperture plane of the optical imaging lens; the image-side lens group is composed of a fourth lens, a fifth lens, and a sixth lens from the object side to the image side; the fourth lens and the fifth lens are cemented together to form a second cemented lens; the second cemented lens has negative optical power, and the sixth lens has positive optical power.

[0006] In one embodiment, the focal length of the optical imaging lens, the focal length of the object-side lens group, and the focal length of the image-side lens group satisfy the following:

[0007]

[0008] Where f is the focal length of the optical imaging lens, f s1 f is the focal length of the object-side lens group. s2 The focal length of the image-side lens group is given.

[0009] In one embodiment, the distance from the vertex of the front surface of the first lens to the vertex of the rear surface of the sixth lens satisfies the following condition with respect to the focal length of the optical imaging lens:

[0010] |L / f|>0.5

[0011] Where f is the focal length of the optical imaging lens, and L is the distance from the vertex of the front surface of the first lens to the vertex of the rear surface of the sixth lens.

[0012] In one embodiment, the optical back intercept from the vertex of the rear surface of the sixth lens to the image side satisfies the following condition:

[0013] |L BFL / f|<0.9

[0014] Where f is the focal length of the optical imaging lens, and L BFL The optical back intercept from the vertex of the rear surface of the sixth lens to the image side.

[0015] In one embodiment, the focal length of the first lens and the focal length of the optical imaging lens satisfy the following:

[0016] 0.8<|f G1 / f|<1

[0017] Where f is the focal length of the optical imaging lens, f G1 Let be the focal length of the first lens.

[0018] In one embodiment, the focal length of the first cemented lens and the focal length of the optical imaging lens satisfy the following:

[0019] 3<|f U1 / f|<5

[0020] Where f is the focal length of the optical imaging lens, f U1 Let be the focal length of the first cemented lens.

[0021] In one embodiment, the focal length of the second cemented lens and the focal length f of the optical imaging lens satisfy the following:

[0022] 1.5<|f U2 / f|<2

[0023] Where f is the focal length of the optical imaging lens, f U2is the focal length of the second cemented lens.

[0024] In one embodiment, the focal length of the sixth lens is the same as the focal length of the optical imaging lens:

[0025] 0.9<|f G6 / f|<1.1

[0026] Where f is the focal length of the optical imaging lens, f G6 The focal length of the sixth lens is given.

[0027] In one embodiment, the first lens, the second lens, the fifth lens, and the sixth lens have positive optical power, and the third lens and the fourth lens have negative optical power; and / or

[0028] The first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical mirrors; wherein,

[0029] The first lens, the second lens, and the sixth lens are biconvex lenses, the third lens is a biconcave lens, the fourth lens is a negative meniscus lens, and the fifth lens is a positive meniscus lens.

[0030] In one embodiment, the high-pass spatial filter is a circular light-shielding structure.

[0031] In one embodiment, the area of ​​the high-pass spatial filter satisfies:

[0032]

[0033] Where S is the area of ​​the high-pass spatial filter, f is the focal length of the optical imaging lens, F is the aperture size corresponding to the lens during imaging, and K ranges from 0.085. <K≤0.099。

[0034] Another aspect of the present invention provides an optical imaging device, including the optical imaging lens for acquiring welding images as described in any of the above embodiments.

[0035] The optical imaging lens of this invention for acquiring welding images focuses the arc light carrying low-frequency spectral information onto the central region of the aperture plane through an object-side lens group. After filtering out the low-frequency region corresponding to the welding background light through a high-pass spatial filter, the image size is restored through an image-side lens group to obtain an image after filtering out the welding arc light spectral information. This can suppress the strong arc light in the welding process, highlight details such as the molten pool and weld seam, and achieve high imaging clarity, thus meeting the observation and monitoring needs of precision manufacturing processes. At the same time, the optical imaging lens of this invention uses fewer lenses, has a more compact structure, and a smaller size, realizing the miniaturization of the welding acquisition lens. It can monitor the welding process in welding scenarios with limited space and at a lower cost. Attached Figure Description

[0036] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0037] Figure 1 This is a schematic diagram of an embodiment of an optical imaging lens according to the present invention;

[0038] Figure 2 yes Figure 1 A schematic diagram of the high-pass spatial filter of the optical imaging lens shown;

[0039] Figure 3a The imaging result is that of an optical imaging lens that does not employ the present invention;

[0040] Figure 3b Is adopted Figure 1 The imaging result of the optical imaging lens of the present invention is shown;

[0041] Figure 4 yes Figure 1 The image shows the lens distortion curve of the optical imaging lens. Detailed Implementation

[0042] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the invention and not to limit it. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the invention without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, the invention is intended to cover these modifications and variations that fall within the scope of the appended claims and their equivalents.

[0043] As used herein, the terms “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components. The term “glued lens” is an optical element in which two or more lenses are bonded together by optical adhesive.

[0044] Figure 1 The structure of the optical imaging lens 4 of the present invention is shown. The optical imaging lens 4 of the present invention for acquiring welding images includes, from the object side 5 to the image side 6, an object-side lens group 1, a filter, and an image-side lens group 2. Both the object-side lens group 1 and the image-side lens group 2 have positive optical power. The object-side lens group 1, from the object side 5 to the image side 6, is composed of a first lens G1, a second lens G2, and a third lens G3. The second lens G2 and the third lens G3 are cemented together to form a first cemented lens U1. The first lens G1 has positive optical power, and the first cemented lens U1 has negative optical power.

[0045] The filter is a high-pass spatial filter 3, used to filter out the low-frequency region corresponding to the welding background light. The high-pass spatial filter 3 is located at the aperture plane of the optical imaging lens 4. The image-side lens group 2 consists of a fourth lens G4, a fifth lens G5, and a sixth lens G6 sequentially from the object side 5 to the image side 6. The fourth lens G4 and the fifth lens G5 are cemented together to form a second cemented lens U2. The second cemented lens U2 has negative optical power, and the sixth lens G6 has positive optical power.

[0046] The optical imaging lens 4 of the present invention for acquiring welding images focuses the arc light carrying low-frequency information onto the central region of the aperture plane through the object-side lens group 1. After filtering out the low-frequency region corresponding to the welding background light through the high-pass spatial filter 3, the image size is restored through the image-side lens group 2 to obtain the image after filtering out the welding arc light spectrum information. This can suppress the strong arc light in the welding process, highlight the details of the molten pool, weld seam, etc., and achieve high imaging clarity, thereby meeting the observation and monitoring needs of precision machining and manufacturing processes.

[0047] Meanwhile, the optical imaging lens 4 of the present invention uses fewer lenses, has a more compact structure, and is smaller in size, realizing the miniaturization of the welding acquisition lens, enabling the monitoring of the welding process in welding scenarios with limited space, and at a lower cost.

[0048] Furthermore, the first lens G1, the second lens G2, the fifth lens G5, and the sixth lens G6 have positive optical power, while the third lens G3 and the fourth lens G4 have negative optical power. The first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, and the sixth lens G6 are all spherical mirrors. Specifically, the first lens G1, the second lens G2, and the sixth lens G6 are biconvex lenses, the third lens G3 is a biconcave lens, the fourth lens G4 is a negative meniscus lens, and the fifth lens G5 is a positive meniscus lens.

[0049] In one embodiment, the focal length of the optical imaging lens 4, the focal length of the object-side lens group 1, and the focal length of the image-side lens group 2 satisfy the following:

[0050]

[0051] In equation (1), f is the focal length of the optical imaging lens 4, f s1 f is the focal length of object-side lens group 1. s2 This is the focal length of the image-side lens group 2.

[0052] In one embodiment, the distance from the vertex of the front surface of the first lens G1 to the vertex of the rear surface of the sixth lens G6 satisfies the following condition with respect to the focal length of the optical imaging lens 4:

[0053] |L / f|>0.5 (2)

[0054] In equation (2), f is the focal length of the optical imaging lens 4, and L is the distance from the vertex of the front surface of the first lens G1 to the vertex of the rear surface of the sixth lens G6.

[0055] In one embodiment, the optical back intercept from the vertex of the rear surface of the sixth lens G6 to the image side 6 satisfies the following condition:

[0056] |L BFL / f|<0.9 (3)

[0057] In equation (3), f is the focal length of the optical imaging lens 4, and L BFL It is the optical back intercept from the vertex of the back surface of the sixth lens G6 to the image side 6.

[0058] In one embodiment, the focal length of the first lens G1 and the focal length of the optical imaging lens 4 satisfy the following:

[0059] 0.8<|f G1 / f|<1 (4)

[0060] In equation (4), f is the focal length of the optical imaging lens 4. G1 Let G be the focal length of the first lens G1.

[0061] In one embodiment, the focal length of the first cemented lens U1 and the focal length of the optical imaging lens 4 satisfy the following:

[0062] 3<|f U1 / f|<5 (5)

[0063] In equation (5), f is the focal length of the optical imaging lens 4, f U1 Let be the focal length of the first cemented lens U1.

[0064] In one embodiment, the focal length of the second cemented lens U2 and the focal length f of the optical imaging lens 4 satisfy the following:

[0065] 1.5<|f U2 / f|<2 (6)

[0066] In equation (6), f is the focal length of the optical imaging lens 4. U2 Let be the focal length of the second cemented lens U2.

[0067] In one embodiment, the focal length of the sixth lens G6 is the same as the focal length of the optical imaging lens 4:

[0068] 0.9<|f G6 / f|<1.1 (7)

[0069] In equation (7), f is the focal length of the optical imaging lens 4, f G6 This is the focal length of the sixth lens, G6.

[0070] In one embodiment, the high-pass spatial filter 3 is a circular light-shielding structure. Compared to a teardrop-shaped filter, the circular shape of the high-pass spatial filter 3 of the present invention simplifies the design process, makes it more convenient to use, and reduces lens costs.

[0071] Based on the above embodiments, the area of ​​the high-pass spatial filter 3 satisfies:

[0072]

[0073] In equation (8), S is the area of ​​the high-pass spatial filter 3, f is the focal length of the optical imaging lens 4, F is the aperture size corresponding to the lens during imaging, and K ranges from 0.085. <K≤0.099。

[0074] The value range of K can be obtained from simulation experiments and is an empirical range. If K exceeds the above range, the high-pass spatial filter 3 will fail.

[0075] A specific embodiment of the present invention will be described using the following specific parameters as an example. The physical parameters of each lens and each cemented lens assembly are shown in Table 1 below:

[0076] Table 1 Physical parameters of the optical imaging lens design of the present invention

[0077] surface Radius (mm) Thickness (mm) Refractive index surface flat 100 G1 front surface 23.4 3 1.9 G1 rear surface -256.9 0.8 U1 front surface 11.5 3.9 1.6 U1 Adhesive Surface -1900 0.58 1.8 U1 rear surface 10.2 3.1 Aperture plane (S) flat 4 U2 front surface -11.3 1.8 1.7 U2 adhesive surface -173.4 2.5 1.6 U2 rear surface -17.4 1.1 G6 front surface 33.7 3.5 1.6 G6 rear surface -33.7 11.9 Image flat

[0078] In this embodiment, the focal length of the optical imaging lens is f = 25mm, the aperture is D / f = 1 / 2.8, and the focal length of the object-side lens group is f S1 =23.5mm, focal length f of the image-side lens group S2 =39.7mm, the distance L from the vertex of the front surface of the first lens G1 to the vertex of the rear surface of the sixth lens G6 is 24.3mm, and the optical back intercept L BFL =11.9mm, the focal length of the first cemented lens U1 is f U1 = -98.6mm, the focal length of the first lens G1 is f G1 =23.4mm, the focal length of the second cemented lens U2 is f U2 = -46.9mm, the focal length of the sixth lens G6 is f G6 =26.1mm.

[0079] The specific parameters in the above embodiments are shown in Table 2:

[0080] Table 2 Specific Parameters of the Embodiments

[0081] Relationship scope Specific parameters |L / f| |L / f|>0.5 0.96 <![CDATA[|L BFL / f|]]> <![CDATA[|L BFL / f|<0.9]]> 0.48 <![CDATA[|f S1 / f|]]> <![CDATA[0.85<|f S1 / f|<1.15]]> 0.94 <![CDATA[|f S2 / f|]]> <![CDATA[1.4<|f S2 / f|<1.7]]> 1.58 <![CDATA[|f U1 / f|]]> <![CDATA[3<|f U1 / f|<5]]> 3.94 <![CDATA[|f G1 / f|]]> <![CDATA[0.8<|f G1 / f|<1]]> 0.93 <![CDATA[|f U2 / f|]]> <![CDATA[1.5<|f U2 / f|<2]]> 1.87 <![CDATA[|f G6 / f|]]> <![CDATA[0.9<|f G6 / f|<1.1]]> 1.04

[0082] The high-pass spatial filter of the lens aperture surface mounting design in the above embodiments is as follows: Figure 2 As shown.

[0083] Figure 3a This is an unprocessed image, i.e., an image of the welding process taken without using the optical imaging lens of this invention. The current lens focal length is 25mm, the imaging stop is set to the maximum F=2.8, K is selected as 0.09, and the high-pass spatial filter area is calculated to be S=11.2mm². 2 .like Figure 3a As shown, the intense arc light generated during the welding process severely interferes with the imaging of details such as the weld pool and weld seam, resulting in problems such as halo, shadows, and overexposure.

[0084] Will Figure 3a In simulation software, the light source is input into the optical imaging lens of the above-described specific embodiment of the present invention, and the spatially filtered imaging result of the weld pool is as follows: Figure 3b As shown. In Figure 3b In the middle, the brightness of areas with strong background light is significantly reduced, and the contrast of details such as weld seams is improved.

[0085] The optical imaging lens of the present invention has fewer lenses, an overall length of 24.3 mm, and a simpler and more compact overall structure.

[0086] The optical imaging lens of this invention, when applied to welding applications with strong background light, achieves low distortion during close-range imaging through reasonable optimization and matching of lens parameters. Figure 3b The image shown was analyzed, and the analysis results are as follows: Figure 4 As shown. In Figure 4 In the graph, the horizontal axis represents the percentage of distortion, and the vertical axis represents the image height. From... Figure 4 It can be seen that the maximum optical distortion is less than 0.1% across the entire field of view, resulting in low imaging distortion and enabling a more realistic reproduction of the welding scene.

[0087] The optical imaging device of the present invention includes an optical imaging lens for acquiring welding images as described in any of the above embodiments.

[0088] In summary, the optical imaging lens of the present invention can overcome the interference of strong background light on existing welding process acquisition cameras, effectively reduce the impact of strong background light on the imaging of the weld pool, have the highest possible resolution, high imaging clarity, highlight details such as the weld pool and weld seam, improve imaging quality, and reduce imaging distortion, thereby meeting the observation and monitoring needs of precision manufacturing processes and the application requirements of different welding scenarios.

[0089] While achieving the above-mentioned effects, the optical imaging lens of the present invention uses fewer lenses, has a simple and compact structure, and a small lens shape, realizing a miniaturized design for welding acquisition lenses. It can acquire images at the closest possible working distance and capture clear images of the welding process in a limited space, solving the problem of interference caused by the narrow monitoring space.

[0090] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. An optical imaging lens for acquiring welding images, characterized in that, The optical imaging lens, from the object side to the image side, sequentially includes an object-side lens group, a filter, and an image-side lens group; wherein... Both the object-side lens group and the image-side lens group have positive optical power; The object-side lens group consists of a first lens, a second lens, and a third lens sequentially from the object side to the image side. The second lens and the third lens are cemented together to form a first cemented lens; The first lens has positive optical power, and the first cemented lens has negative optical power; The filter is a high-pass spatial filter, and the high-pass spatial filter is located at the aperture plane of the optical imaging lens; The image-side lens group consists of a fourth lens, a fifth lens, and a sixth lens sequentially from the object side to the image side; The fourth lens and the fifth lens are cemented together to form a second cemented lens; The second cemented lens has negative optical power, and the sixth lens has positive optical power; The object-side lens group focuses the arc light carrying low-frequency information into the central region of the aperture surface, and the high-pass spatial filter filters out the low-frequency region corresponding to the welding background light. The focal length of the optical imaging lens, the focal length of the object-side lens group, and the focal length of the image-side lens group satisfy the following: Where f is the focal length of the optical imaging lens, f s1 f is the focal length of the object-side lens group. s2 The focal length of the image-side lens group is given.

2. The optical imaging lens as described in claim 1, characterized in that, The distance from the vertex of the front surface of the first lens to the vertex of the rear surface of the sixth lens satisfies the following condition with respect to the focal length of the optical imaging lens: |L / f|>0.5 Where f is the focal length of the optical imaging lens, and L is the distance from the vertex of the front surface of the first lens to the vertex of the rear surface of the sixth lens.

3. The optical imaging lens as described in claim 1, characterized in that, The optical back intercept from the vertex of the rear surface of the sixth lens to the image side satisfies the following condition: |L BFL / f|<0.9 Where f is the focal length of the optical imaging lens, and L BFL The optical back intercept from the vertex of the rear surface of the sixth lens to the image side.

4. The optical imaging lens as described in claim 1, characterized in that, The focal length of the first lens and the focal length of the optical imaging lens satisfy the following: 0.8<|f G1 / f|<1 Where f is the focal length of the optical imaging lens, f G1 Let be the focal length of the first lens.

5. The optical imaging lens as described in claim 1, characterized in that, The focal length of the first cemented lens and the focal length of the optical imaging lens satisfy the following: 3<|f U1 / f|<5 Where f is the focal length of the optical imaging lens, f U1 Let be the focal length of the first cemented lens.

6. The optical imaging lens as described in claim 1, characterized in that, The focal length of the second cemented lens and the focal length f of the optical imaging lens satisfy the following: 1.5<|f U2 / f|<2 Where f is the focal length of the optical imaging lens, f U2 is the focal length of the second cemented lens.

7. The optical imaging lens as described in claim 1, characterized in that, The focal length of the sixth lens and the focal length of the optical imaging lens are: 0.9<|f G6 / f|<1.1 Where f is the focal length of the optical imaging lens, f G6 The focal length of the sixth lens is given.

8. The optical imaging lens as described in claim 1, characterized in that, The first lens, the second lens, the fifth lens, and the sixth lens have positive optical power, and the third lens and the fourth lens have negative optical power; and / or The first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical mirrors; wherein, The first lens, the second lens, and the sixth lens are biconvex lenses, the third lens is a biconcave lens, the fourth lens is a negative meniscus lens, and the fifth lens is a positive meniscus lens.

9. The optical imaging lens as described in any one of claims 1 to 8, characterized in that, The high-pass spatial filter has a circular light-shielding structure.

10. The optical imaging lens as described in claim 9, characterized in that, The area of ​​the high-pass spatial filter satisfies: Where S is the area of ​​the high-pass spatial filter, f is the focal length of the optical imaging lens, F is the aperture size corresponding to the lens during imaging, and K ranges from 0.

085. <K≤0.099。 11. An optical imaging device, characterized in that, Includes an optical imaging lens for acquiring welding images as described in any one of claims 1-10.

Images