Laser coaxial imaging lens and laser processing system

Abstract

The invention relates to a laser coaxial imaging lens and a laser processing system. The laser coaxial imaging lens sequentially comprises a first lens, a first cemented lens group, a fourth lens, a fifth lens and a second cemented lens group from an object side to an image side along an optical axis, the first lens has positive focal power, and the object side surface of the first lens is a convex surface. The first glued lens group has positive focal power and comprises a second lens and a third lens which are glued with each other, the second lens has positive focal power, and the third lens has negative focal power. The fourth lens has negative focal power, the object side face of the fourth lens is a concave face, the image side face of the fourth lens is a concave face, the fifth lens has negative focal power, and the image side face of the fifth lens is a convex face. The second cemented lens group has negative focal power and comprises a sixth lens and a seventh lens which are cemented with each other, the sixth lens has negative focal power, and the seventh lens has positive focal power. The laser coaxial imaging lens can be applied to a laser processing system to realize coaxial imaging monitoring, and has better imaging quality.

Description

Technical Field

[0001] The present application relates to the technical field of laser coaxial imaging, and in particular to a laser coaxial imaging lens and a laser processing system. Background Art

[0002] In the laser processing system, laser processing monitoring technology is the key link to ensure the quality, efficiency and safety of the laser processing process, and its monitoring accuracy is the key factor to ensure the processing quality, efficiency and controllability. Through high-precision monitoring technology, real-time optimization and control of the laser processing process can be achieved to ensure processing accuracy and efficiency.

[0003] The laser processing system in the related art usually adopts an independent observation system, which has a complex optical path, occupies a large space, and has limited monitoring accuracy. The imaging lens in the coaxial monitoring technology used in the related art usually has poor imaging quality and cannot accurately magnify the laser focus spot, so it is impossible to clearly and accurately monitor and locate the processing position during the laser processing process. Summary of the invention

[0004] Based on this, a laser coaxial imaging lens and a laser processing system are provided to realize coaxial imaging monitoring and have better imaging quality, and can clearly and accurately monitor and locate the processing position during the laser processing.

[0005] According to one aspect of the present application, a laser coaxial imaging lens is provided, and the laser coaxial imaging lens includes, in order from the object side to the image side along the optical axis:

[0006] A first lens having positive optical power, wherein the object side surface of the first lens is convex;

[0007] A first cemented lens group with positive power, the first cemented lens group comprises a second lens and a third lens cemented to each other, the second lens has positive power, the third lens has negative power, the object side surface of the second lens is convex, the image side surface is convex, the object side surface of the third lens is concave, and the image side surface is concave;

[0008] a fourth lens having negative optical power, wherein the object-side surface of the fourth lens is concave and the image-side surface is concave;

[0009] a fifth lens having negative optical power, wherein the image side surface of the fifth lens is a convex surface;

[0010] A second cemented lens group with negative optical power, wherein the second cemented lens group includes a sixth lens and a seventh lens cemented to each other, the sixth lens has negative optical power, the seventh lens has positive optical power, the object side surface of the sixth lens is concave, the image side surface is concave, the object side surface of the seventh lens is convex, and the image side surface is convex.

[0011] In one embodiment, the laser coaxial imaging lens satisfies the following condition:

[0012] 15mm≤R11≤35mm;

[0013] -470mm≤R12≤-440mm;

[0014] -25mm≤R41≤-10mm;

[0015] 10mm≤R42≤25mm;

[0016] -125mm≤R51≤-95mm;

[0017] -25mm≤R52≤-5mm;

[0018] Among them, R11 is the curvature radius of the object side surface of the first lens, R12 is the curvature radius of the image side surface of the first lens, and the image side surface of the first lens is concave; R41 is the curvature radius of the object side surface of the fourth lens, R42 is the curvature radius of the image side surface of the fourth lens; R51 is the curvature radius of the object side surface of the fifth lens, the object side surface of the fifth lens is concave, and R52 is the curvature radius of the image side surface of the fifth lens.

[0019] In one embodiment, the laser coaxial imaging lens satisfies the following condition:

[0020] ︱(R21-R32) / (R21+R32)︱≤0.4;

[0021] 15mm≤R21≤35mm;

[0022] -35mm≤R23≤-15mm;

[0023] 15mm≤R32≤35mm;

[0024] Wherein, R21 is the curvature radius of the object side surface of the second lens, R23 is the curvature radius of the cemented surface of the second lens and the third lens; R32 is the curvature radius of the image side surface of the third lens;

[0025] And / or, the laser coaxial imaging lens satisfies the following conditional formula:

[0026] ︱(R61-R72) / (R61+R72)︱≤0.82;

[0027] -25mm≤R61≤-5mm;

[0028] 15mm≤R67≤35mm;

[0029] -50mm≤R72≤-35mm;

[0030] Among them, R61 is the curvature radius of the object side surface of the sixth lens, R67 is the curvature radius of the bonding surface of the sixth lens and the seventh lens; and R72 is the curvature radius of the image side surface of the seventh lens.

[0031] In one embodiment, the laser coaxial imaging lens satisfies the following condition:

[0032] 0.3≤D1 / D12≤2;

[0033] 0.5≤D2 / D3≤2;

[0034] 0.5≤D4 / D5≤2;

[0035] 0.2≤D6 / D7≤1.6;

[0036] 0.2≤(D2+D3) / D34≤1.67;

[0037] Among them, D1 is the size of the first lens on the optical axis, D12 is the distance from the image side surface of the first lens to the object side surface of the second lens on the optical axis, D2 is the size of the second lens on the optical axis, D3 is the size of the third lens on the optical axis, D4 is the size of the fourth lens on the optical axis, D5 is the size of the fifth lens on the optical axis, D6 is the size of the sixth lens on the optical axis, D7 is the size of the seventh lens on the optical axis, and D34 is the distance from the image side surface of the third lens to the object side surface of the fourth lens on the optical axis.

[0038] In one embodiment, the laser coaxial imaging lens satisfies the following condition:

[0039] 1.4<Nd1<2.2;

[0040] 1.4<Nd2<2.2;

[0041] 1.7<Nd3<2.2;

[0042] 1.6<Nd4<2.2;

[0043] 1.7<Nd5<2.2;

[0044] 1.6<Nd6<2.2;

[0045] 1.7<Nd7<2.2;

[0046] Among them, Nd1 is the material refractive index of the first lens, Nd2 is the material refractive index of the second lens, Nd3 is the material refractive index of the third lens, Nd4 is the material refractive index of the fourth lens, Nd5 is the material refractive index of the fifth lens, Nd6 is the material refractive index of the sixth lens, and Nd7 is the material refractive index of the seventh lens.

[0047] In one embodiment, the laser coaxial imaging lens further includes a filter, wherein the filter is disposed on a side of the seventh lens away from the sixth lens along the optical axis;

[0048] Along the optical axis, a distance D78 between the image side surface of the seventh lens and the filter on the optical axis satisfies 5mm≤D78≤15mm, a size D8 of the filter on the optical axis satisfies: 1≤D8≤3mm; a distance D89 between the filter and the image plane on the optical axis satisfies: 20mm≤D89≤40mm.

[0049] In one embodiment, the laser coaxial imaging lens satisfies the following condition:

[0050] 70<Vd1<85;

[0051] 70<Vd2<85;

[0052] 10<Vd3<25;

[0053] 45<Vd4<60;

[0054] 10<Vd5<25;

[0055] 45<Vd6<60;

[0056] 10<Vd7<25;

[0057] 61<Vd8<68;

[0058] Among them, Vd1 is the Abel coefficient of the first lens, Vd2 is the Abel coefficient of the second lens, Vd3 is the Abel coefficient of the third lens, Vd4 is the Abel coefficient of the fourth lens, Vd5 is the Abel coefficient of the fifth lens, Vd6 is the Abel coefficient of the sixth lens, Vd7 is the Abel coefficient of the seventh lens, and Vd8 is the Abel coefficient of the filter.

[0059] According to another aspect of the present application, a laser processing system is provided for processing a workpiece, comprising the laser coaxial imaging lens described in any one of the above embodiments, and the laser processing system further comprises:

[0060] A working light source, used for emitting working light;

[0061] A monitoring light source, used for emitting monitoring light;

[0062] A semi-transparent and semi-reflective mirror and a galvanometer mirror are sequentially arranged along the propagation direction of the working light, the working light is reflected by the semi-transparent and semi-reflective mirror to the galvanometer mirror, and then reflected by the galvanometer mirror to the workpiece;

[0063] The monitoring light source is disposed on a side of the workpiece facing the galvanometer, the monitoring light emitted by the monitoring light source is reflected by the workpiece to the galvanometer, and is reflected by the galvanometer and passes through the semi-transparent and semi-reflective mirror to the laser coaxial imaging lens; and

[0064] The camera is arranged on a side of the laser coaxial imaging lens away from the semi-transparent and semi-reflective mirror, so as to receive the monitoring light passing through the laser coaxial imaging lens.

[0065] In one embodiment, the laser processing system further includes a field lens, wherein the field lens is disposed between the galvanometer mirror and the workpiece.

[0066] In one embodiment, the laser processing system also includes an aperture, which is arranged between the galvanometer and the semi-transparent and semi-reflective mirror, and the distance D0 between the aperture and the semi-transparent and semi-reflective mirror on the optical axis satisfies: 20mm≤D0≤50mm, and the radius a of the spot formed by the monitoring light received by the camera satisfies: 2.246μm≤a≤5.569μm.

[0067] In the above-mentioned laser coaxial imaging lens, the first lens has a positive focal length, which can improve the light collection capability of the edge field of view while reducing the working aperture of the first lens. The object side is a convex surface, which can reduce the spherical aberration and aberration generated when the lenses are coupled, and reduce the angle of the light after it is incident on the lens. The first glued lens group and the second glued lens group are both glued, and by gluing lenses with different refractive indices and dispersion characteristics together, chromatic aberration can be effectively reduced. At the same time, the reflection loss between the lens surfaces can be reduced, the transmittance of light can be improved, the efficiency of the optical system can be improved, the assembly sensitivity of the laser coaxial imaging lens can be reduced, the assembly yield can be improved, and the total optical length of the laser coaxial imaging lens can be reduced. The first glued lens group has a positive focal length, which can cooperate with the first lens to converge the light, make the light transition smoothly, and improve the light quality. The cooperation of the second lens and the third lens in the first glued lens group can effectively correct the chromatic aberration of the laser coaxial imaging lens, balance the aberration of the laser coaxial imaging lens, reduce the eccentricity sensitivity of the laser coaxial imaging lens, and improve the imaging quality of the laser coaxial imaging lens. The cooperation of the sixth lens and the seventh lens in the second cemented lens group can effectively reduce chromatic aberration and spherical aberration, which is beneficial to improving the imaging quality of the laser coaxial imaging lens. The fourth lens and the fifth lens both have negative optical power, which is beneficial to increase the imaging area of ​​the laser coaxial imaging lens, and the two can cooperate with each other to diffuse the light, which is beneficial to diffuse the light while reducing the light deflection angle, allowing the light trend to transition smoothly, and improving the imaging quality of the laser coaxial imaging lens. And the surface design of the two is conducive to correcting the distortion and chromatic aberration caused by the refraction of light, while greatly reducing the spherical aberration and coma generated during the coupling between lenses, further improving the imaging quality. That is, the laser coaxial imaging lens of the present application has better imaging quality. When used in a laser processing system, it can clearly and accurately monitor and locate the processing position during the laser processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 The figure is a schematic diagram of the structure of a laser coaxial imaging lens in one embodiment of the present application.

[0069] Figure 2 It is a schematic diagram of the structure of a laser processing system in one embodiment of the present application.

[0070] Figure 3 This is a spot diagram of a laser coaxial imaging lens in one embodiment of the present application.

[0071] Figure 4 This is a light fan diagram of a laser coaxial imaging lens in an embodiment of the present application.

[0072] Figure 5 This is a transfer function curve diagram of a laser coaxial imaging lens in an embodiment of the present application.

[0073] Figure 6 The field curvature and distortion curves of the laser coaxial imaging lens in one embodiment of the present application are shown in FIG.

[0074] Description of Figure Numbers:

[0075] 10. Laser coaxial imaging lens;

[0076] L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, filter;

[0077] 20. Laser processing system;

[0078] 1. Working light source; 2. Monitoring light source; 3. Semi-transparent and semi-reflective mirror; 4. Galvanometer; 5. Camera; 6. Field lens; 7. Aperture; 8. Workpiece. DETAILED DESCRIPTION

[0079] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0080] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0081] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0082] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0083] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0084] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0085] Laser has three characteristics, namely monochromaticity, directionality, and coherence, which enable laser to be focused into a very small spot and obtain extremely high power density. Since its advent in the 1960s, laser processing technology has experienced rapid development and wide application. At present, laser processing technology is widely used in precision manufacturing, biomedicine, semiconductors and other fields.

[0086] However, the monitoring method of the laser processing process in the related art usually adopts an independent observation system, which is to place an independent optical microscope next to the laser processing system and observe the workpiece through an auxiliary light source. It has the problems of complex optical path, large space occupation, and limited accuracy. In addition, the imaging lens in the coaxial monitoring technology used in the related art usually has poor imaging quality and cannot accurately magnify the light spot of the laser focus, so it is impossible to clearly and accurately monitor and locate the processing position during the laser processing process. It is difficult to achieve perfect coaxiality between the laser processing path and the monitoring observation light path, and there is a problem of reduced observation accuracy and thus affected processing accuracy. In addition, the existing coaxial imaging lenses generally have a short focal length and cannot magnify the light spot of the laser focus, so it is impossible to clearly and accurately monitor and locate the processing position during the laser processing process to ensure the accuracy and quality of laser processing, which limits the development of certain precision laser processing and microscopic observation applications.

[0087] Based on this, the present application provides a laser coaxial imaging lens and a laser processing system, which can monitor and observe the laser processing process of the processing device in real time. The pattern observed in the present application is completely coaxial with the focus of the laser beam, and can realize the "what you see is what you get" machine vision positioning laser processing. And while realizing coaxial imaging monitoring, it has better imaging quality. The laser coaxial imaging lens of the present application can reach a focal length of up to 300mm, the object field diameter of the laser coaxial imaging lens is 7mm, the F number is 21.46, the maximum distortion value is 0.1370%, and the root mean square spot radius (RMS radius) meets the range of 2.246μm to 5.569μm. It has a better imaging spot size, which is conducive to improving the imaging accuracy, and is more conducive to improving the coaxiality of the working light and the monitoring light, and can monitor and locate the processing position more clearly and accurately during the laser processing process.

[0088] See also Figure 1 As shown, Figure 1 The structure diagram of the laser coaxial imaging lens 10 in one embodiment of the present application. The laser coaxial imaging lens 10 provided in the present application includes a first lens L1, a first cemented lens group, a fourth lens L4, a fifth lens L5 and a second cemented lens group in order from the object side to the image side along the optical axis. The first lens L1 has a positive optical power, which can improve the light collection capability of the edge field of view while reducing the working aperture of the first lens L1, and the object side surface of the first lens L1 is a convex surface, which can reduce the spherical aberration or aberration generated when the lenses are coupled.

[0089] The first cemented lens group has positive focal length, and can cooperate with the first lens L1 to converge the light, so that the light transitions smoothly and the light quality is improved. The first cemented lens group includes a second lens L2 and a third lens L3 that are glued to each other, the second lens L2 has positive focal length, and the third lens L3 has negative focal length. By gluing lenses with different refractive indices and dispersion characteristics together, chromatic aberration can be effectively reduced. The object side surface of the second lens L2 is convex, and the image side surface is convex, and the object side surface of the third lens L3 is concave, and the image side surface is concave. The cooperation of the second lens L2 and the third lens L3 can effectively correct the chromatic aberration of the laser coaxial imaging lens 10, balance the aberration of the laser coaxial imaging lens 10, reduce the eccentricity sensitivity of the laser coaxial imaging lens 10, and improve the imaging quality of the laser coaxial imaging lens 10.

[0090] The object side surface of the fourth lens L4 is concave, the image side surface is concave, and the image side surface of the fifth lens L5 is convex. The fourth lens L4 and the fifth lens L5 both have negative optical power, which is beneficial to increase the imaging area of ​​the laser coaxial imaging lens 10, and the two can cooperate with each other to diffuse the light, which is beneficial to diffuse the light while reducing the light deflection angle, so that the light trend transitions smoothly, and improves the imaging quality of the laser coaxial imaging lens 10.

[0091] The second cemented lens group has a negative optical focal length, and can further cooperate with the fourth lens L4 and the fifth lens L5 to diffuse the light, which is beneficial to reduce the light deflection angle and make the light transition smoothly. The second cemented lens group includes a sixth lens L6 and a seventh lens L7 that are glued to each other. The sixth lens L6 has a negative optical focal length, and the seventh lens L7 has a positive optical focal length. By gluing lenses with different refractive indices and dispersion characteristics together, chromatic aberration can be effectively reduced. The object side surface of the sixth lens L6 is a concave surface, and the image side surface is a concave surface. The object side surface of the seventh lens L7 is a convex surface, and the image side surface is a convex surface. Through the cooperation of the negative and positive optical focal lengths of the sixth lens L6 and the seventh lens L7, chromatic aberration and spherical aberration can be effectively reduced, which is beneficial to improving the imaging quality of the laser coaxial imaging lens 10.

[0092] Moreover, both the first glued lens group and the second glued lens group are glued together, which can reduce the reflection loss between the lens surfaces, improve the transmittance of light, improve the efficiency of the optical system, and also reduce the assembly sensitivity of the laser coaxial imaging lens 10, improve the assembly yield, and help reduce the total optical length of the laser coaxial imaging lens 10.

[0093] The laser coaxial imaging lens 10 of the present application makes the light transition smoothly through the design of the first lens L1, the first cemented lens group, the fourth lens L4, the fifth lens L5 and the second cemented lens group, and can greatly reduce the spherical aberration and aberration generated when the lenses are coupled, and at the same time greatly reduce the coma generated when the lenses are coupled, thereby improving the imaging quality of the laser coaxial imaging lens 10. It can also reduce the reflection loss between the lens surfaces, improve the transmittance of light, improve the efficiency of the optical system, reduce the assembly sensitivity of the laser coaxial imaging lens 10, improve the assembly yield, and reduce the total optical length of the laser coaxial imaging lens 10. That is, the laser coaxial imaging lens 10 of the present application has better imaging quality.

[0094] Table 1

[0095]

[0096] In some embodiments, refer to Table 1 above, which shows the parameters of each optical element in the laser coaxial imaging lens 10. The laser coaxial imaging lens 10 satisfies the following conditional formula: 15mm≤R11≤35mm; -470mm≤R12≤-440mm; -25mm≤R41≤-10mm; 10mm≤R42≤25mm; -125mm≤R51≤-95mm; -25mm≤R52≤-5mm. Among them, R11 is the radius of curvature of the object side of the first lens L1, and R12 is the radius of curvature of the image side of the first lens L1. The image side of the first lens L1 is convex, and its convex surface can help converge light, facilitate smooth transition of light, and reduce spherical aberration generated when light is focused. R41 is the curvature radius of the object side surface of the fourth lens L4, R42 is the curvature radius of the image side surface of the fourth lens L4, R51 is the curvature radius of the object side surface of the fifth lens L5, and the object side surface of the fifth lens L5 is concave to help disperse the light, further facilitate the smooth transition of the light, and improve the imaging quality. R52 is the curvature radius of the image side surface of the fifth lens L5.

[0097] Satisfying the above formula, the lenses in the laser coaxial imaging lens 10 all have a better surface shape, which is beneficial to the optimization of the spherical aberration of the lens, to the improvement of the imaging quality, to the reduction of the optical longitudinal length, to the miniaturization design of the laser coaxial imaging lens 10, and to the reduction of the difficulty of processing and manufacturing. That is, the above design is beneficial to the optimization of the lens.

[0098] In some embodiments, referring to Table 1 above, the laser coaxial imaging lens 10 satisfies the following conditional formula: |(R21-R32) / (R21+R32)|≤0.4, 15mm≤R21≤35mm, -35mm≤R23≤-15mm, 15mm≤R32≤35mm. Among them, R21 is the radius of curvature of the object side of the second lens L2, R23 is the radius of curvature of the cemented surface of the second lens L2 and the third lens L3; R32 is the radius of curvature of the image side of the third lens L3. Satisfying the above formula is beneficial to the first cemented lens group to correct axial chromatic aberration and spherical aberration, and to correct field curvature, while reducing the difficulty of processing.

[0099] In some embodiments, referring to Table 1 above, the laser coaxial imaging lens 10 satisfies the following conditional formula: |(R61-R72) / (R61+R72)|≤0.82, -25mm≤R61≤-5mm, 15mm≤R67≤35mm, -50mm≤R72≤-35mm. Among them, R61 is the radius of curvature of the object side of the sixth lens L6, R67 is the radius of curvature of the cemented surface of the sixth lens L6 and the seventh lens L7; R72 is the radius of curvature of the image side of the seventh lens L7. Satisfying the above formula is conducive to the second cemented lens group correcting axial chromatic aberration and spherical aberration, and at the same time helps to reduce the difficulty of processing.

[0100] In some embodiments, referring to Table 1, the laser coaxial imaging lens 10 satisfies the following conditional formula: 0.3≤D1 / D12≤2, 0.5≤D2 / D3≤2, 0.5≤D4 / D5≤2, 0.2≤D6 / D7≤1.6, 0.2≤(D2+D3) / D34≤1.67. Wherein, D1 is the size of the first lens L1 on the optical axis, D12 is the distance from the image side surface of the first lens L1 to the object side surface of the second lens L2 on the optical axis, D2 is the size of the second lens L2 on the optical axis, D3 is the size of the third lens L3 on the optical axis, D4 is the size of the fourth lens L4 on the optical axis, D5 is the size of the fifth lens L5 on the optical axis, D6 is the size of the sixth lens L6 on the optical axis, D7 is the size of the seventh lens L7 on the optical axis, and D34 is the distance from the image side surface of the third lens L3 to the object side surface of the fourth lens L4 on the optical axis. The above formula is satisfied, the center thickness of the lens is moderate, the gap between the lenses is small, the structure is compact, and the total length of the laser coaxial imaging lens 10 is short.

[0101] Continuing to refer to Table 1, in some embodiments, the laser coaxial imaging lens 10 further satisfies the following conditional formula: 3 mm ≤ D1 ≤ 10 mm, 5 mm ≤ D12 ≤ 10 mm, 5 mm ≤ D2 ≤ 10 mm, 5 mm ≤ D3 ≤ 10 mm, 30 mm ≤ D34 ≤ 45 mm, 5 mm ≤ D4 ≤ 10 mm, 5 mm ≤ D45 ≤ 10 mm, 5 mm ≤ D5 ≤ 10 mm, 5 mm ≤ D56 ≤ 10 mm, 2 mm ≤ D6 ≤ 8 mm, 5 mm ≤ D7 ≤ 10 mm, 5 mm ≤ D78 ≤ 15 mm. Wherein, D45 is the distance from the image side surface of the fourth lens L4 to the object side surface of the fifth lens L5 on the optical axis, and D56 is the distance from the image side surface of the fifth lens L5 to the object side surface of the sixth lens L6 on the optical axis. If the above formula is satisfied, the center thicknesses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 will not be less than 2 mm, which is beneficial to the molding and mass production of each lens.

[0102] In some embodiments, referring to Table 1, the laser coaxial imaging lens 10 satisfies the following conditional formula: 1.4<Nd1<2.2, 1.4<Nd2<2.2, 1.7<Nd3<2.2, 1.6<Nd4<2.2, 1.7<Nd5<2.2, 1.6<Nd6<2.2, 1.7<Nd7<2.2. Wherein, Nd1 is the material refractive index of the first lens L1, Nd2 is the material refractive index of the second lens L2, Nd3 is the material refractive index of the third lens L3, Nd4 is the material refractive index of the fourth lens L4, Nd5 is the material refractive index of the fifth lens L5, Nd6 is the material refractive index of the sixth lens L6, and Nd7 is the material refractive index of the seventh lens L7. When the above formula is satisfied, the materials between the multiple lenses can be better matched, the degree of freedom of material selection and matching is high, and the chromatic aberration can be better reduced.

[0103] In some embodiments, see Figure 1 The laser coaxial imaging lens 10 further includes a filter L8, which is disposed on the side of the seventh lens L7 away from the sixth lens L6 along the optical axis. It is used to filter out light of unnecessary wavelengths. For example, the filter can be an infrared cutoff filter, which is used to weaken or filter out at least part of the infrared light. This reduces background noise and interference, enhances image contrast, and improves imaging quality.

[0104] In some embodiments, as shown in Table 1 above, along the optical axis, the distance D78 between the image side surface of the seventh lens L7 and the filter L8 on the optical axis satisfies 5mm≤D78≤15mm, and the size D8 of the filter L8 on the optical axis satisfies: 1≤D8≤3mm. The distance D89 between the filter L8 and the image surface on the optical axis satisfies: 20mm≤D89≤40mm. Satisfying the above formula, the filter L8 has a smaller width and a smaller spacing with the seventh lens L7, which is conducive to the miniaturization design of the laser coaxial imaging lens 10.

[0105] In some embodiments, in combination with the above-mentioned Table 1, the laser coaxial imaging lens 10 satisfies the following conditional formula: 70<Vd1<85, 70<Vd2<85, 10<Vd3<25, 45<Vd4<60, 10<Vd5<25, 45<Vd6<60, 10<Vd7<25, 61<Vd8<68. Wherein, Vd1 is the Abel coefficient of the first lens L1, or the dispersion coefficient. Vd2 is the Abel coefficient of the second lens L2, Vd3 is the Abel coefficient of the third lens L3, Vd4 is the Abel coefficient of the fourth lens L4, Vd5 is the Abel coefficient of the fifth lens L5, Vd6 is the Abel coefficient of the sixth lens L6, Vd7 is the Abel coefficient of the seventh lens L7, and Vd8 is the Abel coefficient of the filter L8. To satisfy the above formula, the first lens L1 is made of a material with a high dispersion coefficient, which is beneficial for the lens to receive light with a larger field angle, while the third lens L3, the fifth lens L5 and the seventh lens L7 are made of a material with a low dispersion coefficient, which is beneficial for optimizing the aberration of the laser coaxial imaging lens 10.

[0106] Combined with reference Figure 2 As shown, Figure 2 It is a schematic diagram of the structure of a laser processing system in one embodiment of the present application.

[0107] The present application also provides a laser processing system 20 for processing a workpiece 8, comprising the laser coaxial imaging lens 10 in any of the above embodiments. The laser processing system 20 also includes a working light source 1, a monitoring light source 2, a semi-transparent and semi-reflecting mirror 3, a galvanometer 4 and a camera 5. The working light source 1 is used to emit working light, and the monitoring light source 2 is used to emit monitoring light. The semi-transparent and semi-reflecting mirror 3 and the galvanometer 4 are arranged in sequence along the propagation direction of the working light. The working light is reflected to the galvanometer 4 through the semi-transparent and semi-reflecting mirror 3, and then reflected to the workpiece 8 through the galvanometer 4. The monitoring light source 2 is arranged on the side of the workpiece 8 facing the galvanometer 4. The monitoring light emitted by the monitoring light source 2 is irradiated to the working surface of the workpiece 8. The position of the working light on the working surface surface coincides with the position of the light spot of the monitoring light on the working surface surface. The monitoring light is then reflected to the galvanometer 4 through the workpiece 8, and is reflected by the galvanometer 4 and passes through the semi-transparent and semi-reflecting mirror 3 to the laser coaxial imaging lens 10. The camera 5 is arranged on the side of the laser coaxial imaging lens 10 away from the semi-transparent and semi-reflecting mirror 3 to receive the monitoring light passing through the laser coaxial imaging lens 10.

[0108] It can be understood that both the working light and the monitoring light pass through the semi-transparent and semi-reflective mirror 3 and the galvanometer 4 to achieve coaxial propagation, so that the processing process of the working light on the workpiece 8 can be observed in real time through the monitoring light, and the coaxial imaging mode of the monitoring light and the working light can be achieved. The coaxial design ensures the precise alignment between the laser processing path and the observation path, and can monitor and locate the processing position more clearly and accurately during the laser processing process. At the same time, it is conducive to simplifying the components in the laser processing system 20 and saving space. The laser coaxial imaging lens 10 can correct the aberration of the optical system, improve the imaging quality of the monitoring light, and further improve the clarity and accuracy of the monitoring. Compared with the shorter focal length of the coaxial imaging lens in the related art, the laser coaxial imaging lens 10 of the present application has a longer focal length of up to 300 mm, achieving a small size and a large focal length. This is especially important for the laser processing system 20 that requires a larger working space, avoiding the risk of collision between the lens and the workpiece 8. The reduction in the space occupied is conducive to space saving, facilitating the operation and maintenance of the laser processing system 20, and the imaging quality is better, making the monitoring of the laser processing system 20 more accurate, which has significant advantages.

[0109] In some embodiments, the monitoring light source 2 is a green light source, and the wavelength range of the emitted monitoring light is 522nm to 542nm, with a central wavelength of 532nm. The working light source 1 is a near-infrared light source, with a central wavelength of 1064nm. Selecting a green light source with a wavelength of 532nm can reduce potential interference with the processing light, because the difference between 532nm (green) and 1064nm (near infrared) ensures that the spectral overlap is small, and the 1064nm laser will not significantly affect the coaxial monitoring light. At the same time, the 532nm green light source can maintain sufficient visibility on various workpiece 8 materials to achieve clear observation.

[0110] It can be understood that only a green light source is used as the monitoring light source 2, so that the laser coaxial imaging lens 10 is a single-wavelength imaging, which avoids the chromatic aberration and spectral interference that may occur in the laser coaxial imaging lens 10 during multi-wavelength imaging, and ensures the clarity and accuracy of the image. The single-wavelength design also simplifies the optical design of the laser processing system 20, reduces the cost and improves the stability of the laser processing system 20.

[0111] In some embodiments, the camera 5 may be a CCD camera to obtain precise and clear images.

[0112] In some embodiments, the laser processing system 20 further includes a field lens 6, which is disposed between the galvanometer 4 and the workpiece 8. By setting the field lens 6 and the laser coaxial imaging lens 10, a double telecentric design is realized. No matter how the workpiece 8 moves within the focal depth range, the magnification of the monitoring light remains constant, and the size and shape of the final image will not change, which simplifies the image processing and measurement process without the need for complex geometric correction. In addition, the fixed magnification and telecentric optical path design can make the image have a stable magnification within a certain focal depth range, which is beneficial for operators to observe tiny details and make precise adjustments to processing parameters.

[0113] The laser coaxial imaging lens 10 can cooperate with the field lens 6 to correct the aberration of the field lens 6 itself. The cooperation between the laser coaxial imaging lens 10 and the field lens 6 optimizes the optical performance of the system, reduces aberrations, and maximizes the imaging quality and the monitoring resolution. The use of high-quality optical components can ensure clear and sharp images for reliable process monitoring. This can further improve the resolution of observation while providing a stable and consistent magnification.

[0114] In some embodiments, the laser processing system 20 further includes an aperture 7, which is disposed between the galvanometer 4 and the semi-transparent and semi-reflective mirror 3, and the aperture 7 may be a light inlet of the mechanical housing of the galvanometer 4. The spacing D0 between the aperture 7 and the semi-transparent and semi-reflective mirror 3 on the optical axis satisfies: 20mm≤D0≤50mm, and the radius a of the light spot formed by the monitoring light received by the camera 5 satisfies: 2.246μm≤a≤5.569μm. Thus, there is a small interval between the aperture 7 and the semi-transparent and semi-reflective mirror 3, which is conducive to the miniaturization design of the laser processing system 20. In addition, the aperture 7 limits the size of the light, limits the lateral propagation of the light, controls the intensity, distribution and direction of the light, greatly reduces the dark angle that often occurs in the system with a separate optical path, ensures uniform illumination and imaging in the entire field of view, is conducive to obtaining a light spot with a better size, is conducive to improving the processing effect of the working light on the workpiece 8, and at the same time, is conducive to improving the quality of the light spot formed by the monitoring light on the camera 5, and is conducive to improving the monitoring accuracy.

[0115] In some embodiments, the size x of the semi-transparent and semi-reflective mirror 3 on the optical axis satisfies: 20≤x≤40mm, and the spacing y between the image side surface of the semi-transparent and semi-reflective mirror 3 and the object side surface of the first lens L1 on the optical axis satisfies: 5≤y≤20mm. Thus, the semi-transparent and semi-reflective mirror 3 can have a better spacing with the first lens L1 while transmitting the monitoring light and reflecting the working light, which is beneficial to the optimization of the laser processing system 20.

[0116] The laser coaxial imaging lens 10 and the laser processing system 20 of the present application have better imaging quality. Figure 3 As shown, Figure 3 This is a spot diagram of the laser coaxial imaging lens 10 in one embodiment of the present application. It can be seen that most of the diffuse spots are concentrated within the Airy disk, indicating that the imaging quality of the laser coaxial imaging lens 10 is relatively good. Figure 4 This is a light fan diagram of the laser coaxial imaging lens 10 in one embodiment of the present application. It shows the aberration correction of the laser coaxial imaging lens 10. It can be seen from the figure that the aberrations such as spherical aberration, coma and astigmatism of the laser coaxial imaging lens 10 are effectively corrected. Figure 5 The transfer function curve of the laser coaxial imaging lens 10 in one embodiment of the present application is shown in the figure. As can be seen from the figure, the laser coaxial imaging lens 10 has a high resolution and clarity, and a good imaging quality. Figure 6 The field curvature and distortion curve of the laser coaxial imaging lens 10 in one embodiment of the present application is shown. The field curvature and distortion of the laser coaxial imaging lens 10 are shown. As can be seen from the figure, the ideal image plane and the actual image plane are almost completely overlapped, and the laser coaxial imaging lens 10 has better anti-distortion capability, thereby having better imaging quality.

[0117] The present application can realize the coaxial imaging of the working light path and the monitoring light path through the design of the laser coaxial imaging lens 10, the semi-transparent and semi-reflective mirror 3, the galvanometer 4, the field lens 6, the working light source 1 and the monitoring light source 2, which is conducive to real-time monitoring of the working state of the working light source 1 on the workpiece 8, and is conducive to improving the accuracy of monitoring. In addition, the laser coaxial imaging lens 10 is conducive to reducing aberrations, spherical aberrations and field curvatures through the coordinated design of multiple lenses, and can correct chromatic aberrations, and has better imaging quality, which is conducive to further improving the accuracy of monitoring, and can clearly and accurately monitor and locate the processing position during the laser processing process. At the same time, the laser coaxial imaging lens 10 adopts a glued lens group, and the size of multiple lenses and the spacing between adjacent lenses are designed, which is conducive to reducing the size of the laser coaxial imaging lens 10 and facilitating miniaturization design.

[0118] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A laser coaxial imaging lens, characterized in that: The laser coaxial imaging lens includes, in order from the object side to the image side along the optical axis: A first lens having positive optical power, wherein the object side surface of the first lens is convex; A first cemented lens group with positive power, the first cemented lens group comprises a second lens and a third lens cemented to each other, the second lens has positive power, the third lens has negative power, the object side surface of the second lens is convex, the image side surface is convex, the object side surface of the third lens is concave, and the image side surface is concave; a fourth lens having negative optical power, wherein the object-side surface of the fourth lens is concave and the image-side surface is concave; a fifth lens having negative optical power, wherein the image side surface of the fifth lens is a convex surface; A second cemented lens group with negative optical power, wherein the second cemented lens group includes a sixth lens and a seventh lens cemented to each other, the sixth lens has negative optical power, the seventh lens has positive optical power, the object side surface of the sixth lens is concave, the image side surface is concave, the object side surface of the seventh lens is convex, and the image side surface is convex.

2. The laser coaxial imaging lens according to claim 1, characterized in that: The laser coaxial imaging lens satisfies the following conditional formula: 15mm≤R11≤35mm; -470mm≤R12≤-440mm; -25mm≤R41≤-10mm; 10mm≤R42≤25mm; -125mm≤R51≤-95mm; -25mm≤R52≤-5mm; Among them, R11 is the curvature radius of the object side surface of the first lens, R12 is the curvature radius of the image side surface of the first lens, and the image side surface of the first lens is concave; R41 is the curvature radius of the object side surface of the fourth lens, R42 is the curvature radius of the image side surface of the fourth lens; R51 is the curvature radius of the object side surface of the fifth lens, the object side surface of the fifth lens is concave, and R52 is the curvature radius of the image side surface of the fifth lens.

3. The laser coaxial imaging lens according to claim 1, characterized in that: The laser coaxial imaging lens satisfies the following conditional formula: ︱(R21-R32) / (R21+R32)︱≤0.4; 15mm≤R21≤35mm; -35mm≤R23≤-15mm; 15mm≤R32≤35mm; Wherein, R21 is the curvature radius of the object side surface of the second lens, R23 is the curvature radius of the cemented surface of the second lens and the third lens; R32 is the curvature radius of the image side surface of the third lens; And / or, the laser coaxial imaging lens satisfies the following conditional formula: ︱(R61-R72) / (R61+R72)︱≤0.82; -25mm≤R61≤-5mm; 15mm≤R67≤35mm; -50mm≤R72≤-35mm; Among them, R61 is the curvature radius of the object side surface of the sixth lens, R67 is the curvature radius of the bonding surface of the sixth lens and the seventh lens; and R72 is the curvature radius of the image side surface of the seventh lens.

4. The laser coaxial imaging lens according to claim 1, characterized in that: The laser coaxial imaging lens satisfies the following conditional formula: 0.3≤D1 / D12≤2; 0.5≤D2 / D3≤2; 0.5≤D4 / D5≤2; 0.2≤D6 / D7≤1.6; 0.2≤(D2+D3) / D34≤1.67; Among them, D1 is the size of the first lens on the optical axis, D12 is the distance from the image side surface of the first lens to the object side surface of the second lens on the optical axis, D2 is the size of the second lens on the optical axis, D3 is the size of the third lens on the optical axis, D4 is the size of the fourth lens on the optical axis, D5 is the size of the fifth lens on the optical axis, D6 is the size of the sixth lens on the optical axis, D7 is the size of the seventh lens on the optical axis, and D34 is the distance from the image side surface of the third lens to the object side surface of the fourth lens on the optical axis.

5. The laser coaxial imaging lens according to claim 1, characterized in that: The laser coaxial imaging lens satisfies the following conditional formula: 1.4<Nd1<2.2; 1.4<Nd2<2.2; 1.7<Nd3<2.2; 1.6<Nd4<2.2; 1.7<Nd5<2.2; 1.6<Nd6<2.2; 1.7<Nd7<2.2; Among them, Nd1 is the material refractive index of the first lens, Nd2 is the material refractive index of the second lens, Nd3 is the material refractive index of the third lens, Nd4 is the material refractive index of the fourth lens, Nd5 is the material refractive index of the fifth lens, Nd6 is the material refractive index of the sixth lens, and Nd7 is the material refractive index of the seventh lens.

6. The laser coaxial imaging lens according to claim 1, characterized in that: The laser coaxial imaging lens further comprises a filter, and the filter is arranged on a side of the seventh lens away from the sixth lens along the optical axis; Along the optical axis, a distance D78 between the image side surface of the seventh lens and the filter on the optical axis satisfies 5mm≤D78≤15mm, a size D8 of the filter on the optical axis satisfies: 1≤D8≤3mm; a distance D89 between the filter and the image plane on the optical axis satisfies: 20mm≤D89≤40mm.

7. The laser coaxial imaging lens according to claim 6, characterized in that: The laser coaxial imaging lens satisfies the following conditional formula: 70<Vd1<85; 70<Vd2<85; 10<Vd3<25; 45<Vd4<60; 10<Vd5<25; 45<Vd6<60; 10<Vd7<25; 61<Vd8<68; Among them, Vd1 is the Abel coefficient of the first lens, Vd2 is the Abel coefficient of the second lens, Vd3 is the Abel coefficient of the third lens, Vd4 is the Abel coefficient of the fourth lens, Vd5 is the Abel coefficient of the fifth lens, Vd6 is the Abel coefficient of the sixth lens, Vd7 is the Abel coefficient of the seventh lens, and Vd8 is the Abel coefficient of the filter.

8. A laser processing system for processing a workpiece, characterized in that: The laser coaxial imaging lens according to any one of claims 1 to 7, wherein the laser processing system further comprises: A working light source, used for emitting working light; A monitoring light source, used for emitting monitoring light; A semi-transparent and semi-reflective mirror and a galvanometer mirror are sequentially arranged along the propagation direction of the working light, the working light is reflected by the semi-transparent and semi-reflective mirror to the galvanometer mirror, and then reflected by the galvanometer mirror to the workpiece; The monitoring light source is disposed on a side of the workpiece facing the galvanometer, the monitoring light emitted by the monitoring light source is reflected by the workpiece to the galvanometer, and is reflected by the galvanometer and passes through the semi-transparent and semi-reflective mirror to the laser coaxial imaging lens; and The camera is arranged on a side of the laser coaxial imaging lens away from the semi-transparent and semi-reflective mirror, so as to receive the monitoring light passing through the laser coaxial imaging lens.

9. The laser processing system according to claim 8, characterized in that: The laser processing system further comprises a field lens, and the field lens is arranged between the galvanometer mirror and the workpiece.

10. The laser processing system according to claim 8, characterized in that: The laser processing system also includes an aperture, which is arranged between the galvanometer and the semi-transparent and semi-reflective mirror. The distance D0 between the aperture and the semi-transparent and semi-reflective mirror on the optical axis satisfies: 20mm≤D0≤50mm, and the radius a of the spot formed by the monitoring light received by the camera satisfies: 2.246μm≤a≤5.569μm.

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