Optical imaging lens and optical imaging device for collecting welding images

Abstract

The invention provides an optical imaging lens and an optical imaging device for collecting welding images. The optical imaging lens sequentially comprises an object side lens group, a filter and an image side lens group from the object side to the image side. The object-side lens group is sequentially 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 to form a first cemented lens. The first lens has positive focal power, and the first balsaming lens has negative focal power. The filter is a high-pass spatial filter and is used for filtering a low-frequency region corresponding to the welding background light, and the high-pass spatial filter is located on a diaphragm surface of the optical imaging lens. The image side lens group is sequentially 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 to form a second cemented lens. The second balsaming lens has negative focal power, and the sixth lens has positive focal power. The optical imaging lens can effectively restrain strong background light interference and is compact in structure.

Description

Technical Field

[0001] The invention relates to optical imaging equipment, and in particular to an optical imaging lens and an optical imaging device for collecting welding images. Background Art

[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. In view of the complex phenomena of sound, light, electricity, heat, magnetism, noise and high-frequency radiation in the welding process, the use of machine vision in automatic welding monitoring has obvious advantages such as intuitive welding image representation and rich feature information, which can meet the requirements of process control for real-time monitoring of the welding molten pool to a certain extent.

[0003] However, strong arc light is generated during the welding process. This strong arc light interference will make the image of the welding area blurred, making it difficult to clearly obtain detailed images such as the welding molten pool and weld. The existing industrial monitoring lenses are difficult to effectively filter the welding arc light and do not have the effect of suppressing strong background light. The actual collected molten pool imaging images cannot meet the needs of subsequent further feature analysis. At the same time, the above-mentioned industrial monitoring lenses are mostly telecentric lenses with large overall size and long working distance, which will interfere in welding scenarios with narrow monitoring space. Summary of the invention

[0004] The object of the present invention is to provide an optical imaging lens and an optical imaging device for collecting welding images, which can effectively suppress strong background light interference and have a compact structure.

[0005] One aspect of the present invention provides an optical imaging lens for collecting welding images, wherein the optical imaging lens comprises an object side lens group, a filter and an image side lens group in sequence from the object side to the image side; wherein the object side lens group and the image side lens group both have positive optical focal length; the object side lens group is composed of a first lens, a second lens and a third lens in sequence from the object side to the image side; the second lens and the third lens are glued together to form a first glued lens; the first lens has positive optical focal length, and the first glued lens has negative optical focal length; the filter is a high-pass spatial filter, and the high-pass spatial filter is located on the aperture surface of the optical imaging lens; the image side lens group is composed of a fourth lens, a fifth lens and a sixth lens in sequence from the object side to the image side; the fourth lens and the fifth lens are glued together to form a second glued lens; the second glued lens has a negative optical focal length, and the sixth lens has a positive optical focal length.

[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:

[0007]

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

[0009] In one embodiment, the distance from the front surface vertex of the first lens to the back surface vertex of the sixth lens and the focal length of the optical imaging lens satisfy:

[0010] |L / f|>0.5

[0011] Wherein, f is the focal length of the optical imaging lens, and L is the distance from the front surface vertex of the first lens to the rear surface vertex 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 and the focal length of the optical imaging lens satisfy:

[0013] |L BFL / f|<0.9

[0014] Wherein, f is the focal length of the optical imaging lens, L BFL is the optical back intercept from the vertex of the back 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:

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

[0017] Wherein, f is the focal length of the optical imaging lens, f G1 is 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:

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

[0020] Wherein, f is the focal length of the optical imaging lens, f U1 is 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:

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

[0023] Wherein, 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 and the focal length of the optical imaging lens are:

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

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

[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 lenses; wherein,

[0029] The first lens, the second lens, the fifth lens and the sixth lens are biconvex structures, and the third lens and the fourth lens are biconcave structures.

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

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

[0032]

[0033] Wherein, 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 the range of K is 0.085 <K≤0.099。

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

[0035] The optical imaging lens for collecting welding images of the present invention converges arc light carrying lower spectrum information on the central area of ​​the aperture surface through the object side lens group, filters out the low-frequency area corresponding to the welding background light through a high-pass spatial filter, and then restores the image size through the image side lens group to obtain an image after filtering out the welding arc spectrum information. The strong arc light in the welding process can be suppressed, and the detailed information such as the molten pool and the weld can be highlighted. The imaging clarity is high, thereby meeting the observation and monitoring requirements of the precision machining and manufacturing process. At the same time, the optical imaging lens of the present invention uses fewer lenses, has a more compact structure, and is smaller in size, thereby realizing the miniaturization of the welding collection lens, and can monitor the welding process in a welding scenario with limited space, and at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0038] Figure 2 yes Figure 1 Schematic diagram of a high-pass spatial filter of an optical imaging lens shown;

[0039] Figure 3a is the imaging result without using the optical imaging lens of 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 lens distortion curve of the optical imaging lens is shown. DETAILED DESCRIPTION

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

[0043] As used herein, the terms "first", "second", "third", "fourth", "fifth" and "sixth" may be used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of the respective components. The term "cemented lens" is an optical element in which two or more lenses are bonded together by optical glue.

[0044] Figure 1The structure of the optical imaging lens 4 of the present invention is shown. The optical imaging lens 4 for collecting welding images of the present invention includes an object side lens group 1, a filter and an image side lens group 2 from the object side 5 to the image side 6. Among them, the object side lens group 1 and the image side lens group 2 both have positive optical focal length. The object side lens group 1 is composed of a first lens G1, a second lens G2 and a third lens G3 from the object side 5 to the image side 6. The second lens G2 and the third lens G3 are glued to form a first glued lens U1. The first lens G1 has a positive optical focal length, and the first glued lens U1 has a negative optical focal length.

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

[0046] The optical imaging lens 4 for collecting welding images of the present invention converges arc light carrying lower spectrum information on the central area of ​​the aperture surface through the object side lens group 1, filters out the low-frequency area corresponding to the welding background light through the high-pass spatial filter 3, and then restores the image size through the image side lens group 2 to obtain an image after filtering out the welding arc spectrum information. This can suppress the strong arc light in the welding process, highlight the detailed information such as the molten pool and the weld, and has high imaging clarity, thereby being able to meet the observation and monitoring needs of the precision machining and manufacturing process.

[0047] At the same time, the optical imaging lens 4 of the present invention uses fewer lenses, has a more compact structure, and is smaller in size, thereby realizing the miniaturization of the welding collection lens, being able to monitor 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 power, and the third lens G3 and the fourth lens G4 have negative 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 lenses. Among them, the first lens G1, the second lens G2, the fifth lens G5 and the sixth lens G6 are biconvex structures, and the third lens G3 and the fourth lens are biconcave structures.

[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:

[0050]

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

[0052] In one embodiment, the distance from the front surface vertex of the first lens G1 to the back surface vertex of the sixth lens G6 and the focal length of the optical imaging lens 4 satisfy:

[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 front vertex of the first lens G1 to the back vertex 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 and the focal length of the optical imaging lens 4 satisfy:

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

[0057] In equation (3), f is the focal length of the optical imaging lens 4, L BFL It is the optical back intercept from the back surface vertex 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:

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

[0060] In equation (4), f is the focal length of the optical imaging lens 4, and f G1 is 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:

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

[0063] In equation (5), f is the focal length of the optical imaging lens 4, f U1 is 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:

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

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

[0067] In one embodiment, the focal length of the sixth lens G6 and the focal length of the optical imaging lens 4 are:

[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 is the focal length of the sixth lens G6.

[0070] In one embodiment, the high-pass spatial filter 3 is in the shape of a circular light-shielding structure. Compared with a filter in a water droplet-shaped structure, the high-pass spatial filter 3 of the present invention is in the shape of a circle, which can make the design process simpler, more convenient to use, and reduce the lens cost.

[0071] Based on the above embodiment, 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 the range of K is 0.085 <K≤0.099。

[0074] The value range of K can be obtained according to simulation experiments and belongs to the empirical value range. If K exceeds the above range, the high-pass spatial filter 3 fails.

[0075] A specific embodiment of the present invention is described by taking the following specific parameters as an example. The physical parameters of each lens and each cemented lens group 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 Physical 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 glued surface -1900 0.58 1.8 U1 rear surface 10.2 3.1 Aperture surface (S) flat 4 U2 front surface -11.3 1.8 1.7 U2 glue 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 plane flat

[0078] In this embodiment, the focal length of the optical imaging lens is f=25 mm, 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 of image side lens group f S2 =39.7mm, the distance L from the front vertex of the first lens G1 to the back vertex of the sixth lens G6 = 24.3mm, and the optical back focus 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 fG1 =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 embodiment are shown in Table 2:

[0080] Table 2 Specific parameters of the embodiment

[0081] Relational 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 designed for mounting the lens aperture surface in the above embodiment is as follows: Figure 2 shown.

[0083] Figure 3a It is an unprocessed image, that is, an image of the welding process taken without using the optical imaging lens of the present invention. The current lens focal length is 25mm, the imaging aperture is set to the maximum F=2.8, K is selected to be 0.09, and the high-pass spatial filter area S is calculated to be 11.2mm 2 .like Figure 3a As shown in the figure, the strong arc light generated by the welding process seriously interferes with the imaging of details such as the welding pool and weld, resulting in problems such as halo, shadow and overexposure.

[0084] Will Figure 3a In the simulation software, the light source is input into the optical imaging lens of the above specific embodiment of the present invention, and the welding pool imaging result after spatial filtering is as follows: Figure 3b As shown. Figure 3b In the image, the brightness of the strong background light area is significantly reduced, and the contrast of details such as welds 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] Under the premise that the optical imaging lens of the present invention is suitable for the application scenario of welding strong background light imaging, by reasonably optimizing and matching the lens parameters, it can ensure that the close-range imaging has low distortion. Figure 3b The image shown in the figure is analyzed and the analysis results are as follows Figure 4 As shown. Figure 4 In the figure, the horizontal axis is the distortion percentage and the vertical axis is the image height. Figure 4 It can be obtained that the maximum optical distortion in the entire field of view is less than 0.1%, the imaging distortion is low, and the welding scene can be restored more realistically.

[0087] The optical imaging device of the present invention comprises the optical imaging lens for capturing welding images as described in any one of the above embodiments.

[0088] In summary, the optical imaging lens of the present invention can overcome the interference of strong background light on the existing welding process acquisition camera, effectively reduce the influence of strong background light on the imaging of the welding molten pool, have the highest possible resolution, high imaging clarity, highlight the detailed information of the molten pool, weld, etc., improve the imaging quality, and reduce the imaging distortion, thereby being able to meet the observation and monitoring needs of the precision machining and manufacturing process 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, thereby realizing a miniaturized design of the welding collection lens. It can collect images at the closest possible working distance and take clear images of the welding process in a limited space, thus solving the problem of interference in defects caused by narrow monitoring space.

[0090] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. An optical imaging lens for collecting welding images, characterized in that: The optical imaging lens comprises an object side lens group, a filter and an image side lens group in sequence from the object side to the image side; wherein, The object side lens group and the image side lens group both have positive refractive power; The object side lens group is composed of a first lens, a second lens and a third lens in sequence 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 power, and the first cemented lens has negative power; The filter is a high-pass spatial filter, and the high-pass spatial filter is located on the aperture surface of the optical imaging lens; The image side lens group is composed of a fourth lens, a fifth lens and a sixth lens in sequence 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 power, and the sixth lens has positive power.

2. The optical imaging lens according to claim 1, wherein: 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: Wherein, f is the focal length of the optical imaging lens, f s1 is the focal length of the object side lens group, f s2 is the focal length of the image side lens group.

3. The optical imaging lens according to claim 2, wherein: The distance from the front surface vertex of the first lens to the back surface vertex of the sixth lens and the focal length of the optical imaging lens satisfy: |L / f|>0.5 Wherein, f is the focal length of the optical imaging lens, and L is the distance from the front surface vertex of the first lens to the rear surface vertex of the sixth lens.

4. The optical imaging lens according to claim 2, wherein: The optical back intercept from the vertex of the rear surface of the sixth lens to the image side and the focal length of the optical imaging lens satisfy: |L BFL / f|<0.9 Wherein, f is the focal length of the optical imaging lens, L BFL is the optical back intercept from the vertex of the back surface of the sixth lens to the image side.

5. The optical imaging lens according to claim 2, wherein: The focal length of the first lens and the focal length of the optical imaging lens satisfy: 0.8<|f G1 / f|<1 Wherein, f is the focal length of the optical imaging lens, f G1 is the focal length of the first lens.

6. The optical imaging lens according to claim 2, wherein: The focal length of the first cemented lens and the focal length of the optical imaging lens satisfy: 3<|f U1 / f|<5 Wherein, f is the focal length of the optical imaging lens, f U1 is the focal length of the first cemented lens.

7. The optical imaging lens according to claim 2, wherein: The focal length of the second cemented lens and the focal length f of the optical imaging lens satisfy: 1.5<|f U2 / f|<2 Wherein, f is the focal length of the optical imaging lens, f U2 is the focal length of the second cemented lens.

8. The optical imaging lens according to claim 2, wherein: The focal length of the sixth lens and the focal length of the optical imaging lens: 0.9<|f G6 / f|<1.1 Wherein, f is the focal length of the optical imaging lens, f G6 is the focal length of the sixth lens.

9. The optical imaging lens according to claim 2, wherein: 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 lenses; wherein, The first lens, the second lens, the fifth lens and the sixth lens are biconvex structures, and the third lens and the fourth lens are biconcave structures.

10. The optical imaging lens according to any one of claims 1 to 9, wherein: The high-pass spatial filter is in the shape of a circular light-shielding structure.

11. The optical imaging lens according to claim 10, wherein: The area of ​​the high-pass spatial filter satisfies: Wherein, 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 the range of K is 0.085 <K≤0.099。 12. An optical imaging device, characterized in that: It comprises an optical imaging lens for capturing welding images as described in any one of claims 1-11.

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