Laser coaxial imaging lens and laser processing system

Abstract

The application relates to a laser coaxial imaging lens and a laser processing system. The laser coaxial imaging lens comprises, in sequence from the object side to the image side along the optical axis, a first lens, a first cemented lens group, a fourth lens, a fifth lens and a second cemented lens group. The first lens has positive refractive power, and the object side surface of the first lens is a convex surface. The first cemented lens group has positive refractive power and comprises a second lens and a third lens which are cemented with each other. The second lens has positive refractive power, and the third lens has negative refractive power. The fourth lens has negative refractive power, the object side surface of the fourth lens is a concave surface, the image side surface of the fourth lens is a concave surface, the fifth lens has negative refractive power, and the image side surface of the fifth lens is a convex surface. The second cemented lens group has negative refractive power and comprises a sixth lens and a seventh lens which are cemented with each other. The sixth lens has negative refractive power, and the seventh lens has positive refractive power. The laser coaxial imaging lens can be applied to the 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, in particular to a laser coaxial imaging lens and a laser processing system. BACKGROUND

[0002] In a laser processing system, laser processing monitoring technology is a key link to ensure the quality, efficiency and safety of the laser processing process, and its monitoring precision is a 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 realized to ensure the processing precision 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 is limited in monitoring precision. The imaging lens in the coaxial monitoring technology in the related art usually has poor imaging quality and cannot accurately magnify the laser focal spot, so it cannot clearly and accurately monitor and position the processing position during the laser processing process. SUMMARY

[0004] Therefore, a laser coaxial imaging lens and a laser processing system are provided to achieve coaxial imaging monitoring and have better imaging quality, so that the processing position can be clearly and accurately monitored and positioned during the laser processing process.

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

[0006] a first lens with positive focal power, the object side surface of the first lens being a convex surface;

[0007] a first cemented lens group with positive focal power, the first cemented lens group comprising a second lens and a third lens cemented to each other, the second lens having positive focal power, the third lens having negative focal power, the object side surface of the second lens being a convex surface, the image side surface of the second lens being a convex surface, the object side surface of the third lens being a concave surface, and the image side surface of the third lens being a concave surface;

[0008] a fourth lens with negative focal power, the object side surface of the fourth lens being a concave surface, and the image side surface of the fourth lens being a concave surface;

[0009] a fifth lens with negative focal power, the image side surface of the fifth lens being a convex surface;

[0010] a second cemented lens group with negative focal power, the second cemented lens group comprising a sixth lens and a seventh lens cemented to each other, the sixth lens having negative focal power, the seventh lens having positive focal power, the object side surface of the sixth lens being a concave surface, the image side surface of the sixth lens being a concave surface, the object side surface of the seventh lens being a convex surface, and the image side surface of the seventh lens being a convex surface.

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

[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] wherein 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, 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 conditional expression:

[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; and 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 expression:

[0026] | (R61-R72) / (R61+R72) |≤0.82;

[0027] -25mm≤R61≤-5mm;

[0028] 15mm≤R67≤35mm;

[0029] -50mm≤R72≤-35mm;

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

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

[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] wherein 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 conditional expressions:

[0039] 1.4

[0040] 1.4

[0041] 1.7

[0042] 1.6

[0043] 1.7

[0044] 1.6

[0045] 1.7

[0046] Wherein, 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 of the embodiments, the laser coaxial imaging lens further comprises a filter, which is arranged on the side of the seventh lens away from the sixth lens along the optical axis.

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

[0049] In one of the embodiments, the laser coaxial imaging lens satisfies the following conditional expressions:

[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] Wherein, Vd1 is the Abbe number of the first lens, Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, Vd4 is the Abbe number of the fourth lens, Vd5 is the Abbe number of the fifth lens, Vd6 is the Abbe number of the sixth lens, Vd7 is the Abbe number of the seventh lens, and Vd8 is the Abbe number of the filter.

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

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

[0061] a monitoring light source configured to emit a monitoring light beam;

[0062] a half-transmissive half-reflective mirror and a galvanometer mirror arranged in sequence along a propagation direction of the working light beam, the working light beam being reflected by the half-transmissive half-reflective mirror to the galvanometer mirror and then being reflected by the galvanometer mirror to the workpiece;

[0063] the monitoring light source is arranged on a side of the workpiece facing the galvanometer mirror, the monitoring light beam emitted by the monitoring light source is reflected by the workpiece to the galvanometer mirror, and then is reflected by the galvanometer mirror and transmitted through the half-transmissive half-reflective mirror to the laser coaxial imaging lens; and

[0064] a camera arranged on a side of the laser coaxial imaging lens away from the half-transmissive half-reflective mirror, so as to receive the monitoring light beam transmitted through the laser coaxial imaging lens.

[0065] In one of the embodiments, the laser processing system further comprises a field lens arranged between the galvanometer mirror and the workpiece.

[0066] In one of the embodiments, the laser processing system further comprises a diaphragm arranged between the galvanometer mirror and the half-transmissive half-reflective mirror, and a distance D0 between the diaphragm and the half-transmissive half-reflective mirror on the optical axis satisfies: 20mm≤D0≤50mm, and a radius a of a light spot formed by the monitoring light beam received by the camera satisfies: 2.246μm≤a≤5.569μm.

[0067] The first lens has positive focal power, which can improve the edge field light collection ability while reducing the working aperture of the first lens. The object side is convex, which can reduce the spherical aberration and aberration generated when coupling between lenses, and reduce the angle of light incident to the lens after. The first cemented lens group and the second cemented lens group are both in the form of cementing, which can effectively reduce chromatic aberration by cementing lenses with different refractive indices and dispersion characteristics. At the same time, it can reduce the reflection loss between the lens surfaces, improve the light transmittance, improve the efficiency of the optical system, and also reduce the assembly sensitivity of the laser coaxial imaging lens, improve the assembly yield, and be conducive to reducing the total optical length of the laser coaxial imaging lens. The first cemented lens group has positive focal power, which can cooperate with the first lens to converge light, make the light transition smoothly, improve the light quality, and the cooperation of the second lens and the third lens in the first cemented 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 conducive to improving the imaging quality of the laser coaxial imaging lens. The fourth lens and the fifth lens both have negative focal power, which is conducive to increasing the imaging area of the laser coaxial imaging lens, and the two can cooperate with each other to diffuse light, which is conducive to diffusing light while reducing the light deflection angle, making the light trend 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 light refraction, while greatly reducing the spherical aberration and coma generated when coupling between lenses, further improving the imaging quality. That is, the laser coaxial imaging lens of the present application has better imaging quality, and when used in a laser processing system, it can clearly and accurately monitor and position the processing position during laser processing. BRIEF DESCRIPTION OF DRAWINGS

[0068] Figure 1 FIG. 1 is a structural schematic diagram of a laser coaxial imaging lens in an embodiment of the present application.

[0069] Figure 2 FIG. 3 is a structural schematic diagram of a laser processing system in an embodiment of the present application.

[0070] Figure 3 FIG. 5 is a spot diagram of a laser coaxial imaging lens in an embodiment of the present application.

[0071] Figure 4 FIG. 7 is a light fan diagram of a laser coaxial imaging lens in an embodiment of the present application.

[0072] Figure 5 FIG. 9 is a transfer function curve diagram of a laser coaxial imaging lens in an embodiment of the present application.

[0073] Figure 6 A field curvature and distortion curve diagram of the laser coaxial imaging lens in an embodiment of the present application.

[0074] BRIEF DESCRIPTION OF DRAWINGS

[0075] 10. The 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. The laser processing system;

[0078] 1. Work light source; 2. Monitoring light source; 3. Half-mirror; 4. Galvanometer; 5. Camera; 6. Field lens; 7. Diaphragm; 8. Workpiece. DETAILED DESCRIPTION

[0079] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced in a variety of ways beyond the specific embodiments described herein without departing from the spirit of the present application, and that the present application is not limited to the specific embodiments disclosed below.

[0080] In the description of the present application, it should be understood that if there are terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0081] In addition, if the terms "first", "second" appear, these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "multiple" appears, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0082] In the present application, unless specifically defined otherwise, if there is an appearance of the terms "installation", "connection", "connection", "fixation" and the like, these terms should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically defined. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0083] In the present application, unless specifically defined otherwise, if there is a description of the first feature "on" or "below" the second feature and the like, it can mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0084] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are only for illustrative purposes and do not represent the only implementation.

[0085] Laser has three characteristics, namely monochromaticity, directionality and coherence, which makes laser can be focused into very small spot and get very high power density. Since the emergence of laser processing technology in the 1960s, it has experienced rapid development and wide application. At present, laser processing technology is widely used in precision manufacturing, biological medicine, semiconductor and other fields.

[0086] However, the monitoring method of the laser processing process in the related art generally adopts an independent observation system, that is, an independent optical microscope is placed beside the laser processing system, and the workpiece is observed through an auxiliary light source. However, the optical path is complex, the space occupation is large, the precision is limited, and the like. Moreover, the imaging lens in the coaxial monitoring technology in the related art generally has poor imaging quality, and cannot accurately magnify the laser focal spot, so that the processing position cannot be clearly and accurately monitored and positioned during the laser processing process. It is difficult to realize the perfect coaxiality of the laser processing path and the observation light path for monitoring, and the observation precision is reduced, thereby affecting the processing precision. Moreover, the existing coaxial imaging lens generally has a short focal length, and cannot magnify the laser focal spot, so that the processing position cannot be clearly and accurately monitored and positioned during the laser processing process, and the accuracy and quality of the laser processing are ensured, which limits the development of some precise laser processing and microscopic observation applications.

[0087] Therefore, the laser coaxial imaging lens and the laser processing system are provided to realize real-time positioning and monitoring of the laser processing process of the processing device. The observation pattern of the laser coaxial imaging lens is coaxial with the laser beam focal point, and the machine vision positioning laser processing of "what you see is what you get" can be realized. Moreover, the laser coaxial imaging lens has better imaging quality, and can achieve a focal length of 300 mm, the object field diameter of the laser coaxial imaging lens is 7 mm, the F number is 21.46, the maximum distortion value is 0.1370%, the root mean square (RMS) radius satisfies the range of 2.246 μm to 5.569 μm, the imaging spot size is better, the imaging precision is improved, the coaxiality of the working light and the monitoring light is improved, and the processing position can be more clearly and accurately monitored and positioned during the laser processing process.

[0088] Referring to Figure 1 , Figure 1 The laser coaxial imaging lens 10 is a structure schematic view of an embodiment of the laser coaxial imaging lens 10. The laser coaxial imaging lens 10 provided by the application sequentially includes a first lens L1, a first cemented lens group, a fourth lens L4, a fifth lens L5, and a second cemented lens group along the optical axis from the object side to the image side. The first lens L1 has a positive focal power, can improve the edge field light collection capability 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 refractive power and can cooperate with the first lens L1 to converge light, so that the light is smoothly transitioned and the light quality is improved. The first cemented lens group includes the second lens L2 and the third lens L3 which are cemented with each other, the second lens L2 has positive refractive power, and the third lens L3 has negative refractive power. By cementing lenses with different refractive indices and dispersion characteristics together, chromatic aberration can be effectively reduced. The object side of the second lens L2 is a convex surface, and the image side is a convex surface. The object side of the third lens L3 is a concave surface, and the image side is a concave surface. 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 of the fourth lens L4 is a concave surface, and the image side is a concave surface. The image side of the fifth lens L5 is a convex surface. The fourth lens L4 and the fifth lens L5 both have negative refractive 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 light, which is beneficial to diffuse light while reducing the light deflection angle, so that the light trend is smoothly transitioned, and the imaging quality of the laser coaxial imaging lens 10 is improved.

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

[0092] The first cemented lens group and the second cemented lens group are both cemented, which can reduce the reflection loss between the lens surfaces, improve the light transmittance, 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 optical total length of the laser coaxial imaging lens 10.

[0093] The laser coaxial imaging lens 10 of the present application can make the light transition gently, and can greatly reduce the spherical aberration and aberration generated when coupling between lenses, and at the same time greatly reduce the coma generated when coupling between lenses, and improve the imaging quality of the laser coaxial imaging lens 10. And can reduce the reflection loss between the lens surfaces, improve the light transmittance, 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, referring to Table 1 shown above, Table 1 is the parameter of each optical element in the laser coaxial imaging lens 10. The laser coaxial imaging lens 10 satisfies the following conditional expressions: 15mm≤R11≤35mm; -470mm≤R12≤-440mm; -25mm≤R41≤-10mm; 10mm≤R42≤25mm; -125mm≤R51≤-95mm; -25mm≤R52≤-5mm. Wherein, R11 is the curvature radius of the object side surface of the first lens L1, R12 is the curvature radius of the image side surface of the first lens L1, the image side surface of the first lens L1 is convex, which can help converge light, which is beneficial to make the light transition gently and reduce the spherical aberration generated when focusing light. 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, the object side surface of the fifth lens L5 is concave, which can help disperse light, further benefit the light transition gently, and improve the imaging quality, and R52 is the curvature radius of the image side surface of the fifth lens L5.

[0097] Satisfying the above expressions, the lenses in the laser coaxial imaging lens 10 all have better surface shapes, which is beneficial to the optimization of lens spherical aberration, and is beneficial to improve the imaging quality, reduce the optical length, facilitate the miniaturization design of the laser coaxial imaging lens 10, and at the same time reduce 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 expression: |(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 L2, R23 is the curvature radius of the cemented surface of the second lens L2 and the third lens L3; R32 is the curvature radius of the image side surface of the third lens L3. Satisfying the above expression is conducive to correcting the axial chromatic aberration and spherical aberration of the first cemented lens group, and is conducive to correcting the field curvature, and is conducive to reducing the processing difficulty.

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

[0100] In some embodiments, referring to Table 1 above, the laser coaxial imaging lens 10 satisfies the following conditional expression: 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, 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. Satisfying the above expression is moderate in lens center thickness, small in lens gap, compact in structure, and short in total length of the laser coaxial imaging lens 10.

[0101] Continuing to refer to Table 1, in some embodiments, the laser coaxial imaging lens 10 further satisfies the following conditional expressions: 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 on the optical axis from the image side surface of the fourth lens L4 to the object side surface of the fifth lens L5, and D56 is the distance on the optical axis from the image side surface of the fifth lens L5 to the object side surface of the sixth lens L6. Satisfying the above expressions, the center thickness 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 are all not 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 expressions: 1.4

[0103] In some embodiments, referring to Table 1, the laser coaxial imaging lens 10 further satisfies the following conditional expressions: 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 on the optical axis from the image side surface of the fourth lens L4 to the object side surface of the fifth lens L5, and D56 is the distance on the optical axis from the image side surface of the fifth lens L5 to the object side surface of the sixth lens L6. Satisfying the above expressions, the center thickness 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 are all not less than 2 mm, which is beneficial to the molding and mass production of each lens. Figure 1 In some embodiments, referring to Table 1, the laser coaxial imaging lens 10 further satisfies the following conditional expressions: 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 on the optical axis from the image side surface of the fourth lens L4 to the object side surface of the fifth lens L5, and D56 is the distance on the optical axis from the image side surface of the fifth lens L5 to the object side surface of the sixth lens L6. Satisfying the above expressions, the center thickness 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 are all not less than 2 mm, which is beneficial to the molding and mass production of each lens.

[0104] In some embodiments, referring to 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, 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 plane on the optical axis satisfies: 20mm≤D89≤40mm. Satisfying the above formula, the filter L8 has a smaller width, and the distance between the filter L8 and the seventh lens L7 is smaller, which is beneficial to the miniaturization design of the laser coaxial imaging lens 10.

[0105] In some embodiments, referring to Table 1 above, 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 Abbe number, or the dispersion coefficient, of the first lens L1. Vd2 is the Abbe number of the second lens L2, Vd3 is the Abbe number of the third lens L3, Vd4 is the Abbe number of the fourth lens L4, Vd5 is the Abbe number of the fifth lens L5, Vd6 is the Abbe number of the sixth lens L6, Vd7 is the Abbe number of the seventh lens L7, and Vd8 is the Abbe number of the filter L8. Satisfying the above formula, the first lens L1 adopts a material with a high dispersion coefficient, which is beneficial to the lens to accommodate light with a larger field of view, while the third lens L3, the fifth lens L5 and the seventh lens L7 adopt a material with a low dispersion coefficient, which is beneficial to the optimization of the aberration of the laser coaxial imaging lens 10.

[0106] Referring to Figure 2 , Figure 2 is a structural schematic diagram of a laser processing system in an embodiment of the present application.

[0107] The 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 further comprises a working light source 1 for emitting working light, a monitoring light source 2 for emitting monitoring light, a half-mirror 3, a galvanometer 4, and a camera 5. The half-mirror 3 and the galvanometer 4 are sequentially arranged along the propagation direction of the working light. The working light is reflected by the half-mirror 3 to the galvanometer 4, and then reflected by the galvanometer 4 to the workpiece 8. 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 irradiates the working surface of the workpiece 8, and the position of the working light on the working surface coincides with the spot position of the monitoring light on the working surface. The monitoring light is reflected by the workpiece 8 to the galvanometer 4, and then reflected by the galvanometer 4 and transmitted through the half-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 half-mirror 3, for receiving the monitoring light passing through the laser coaxial imaging lens 10.

[0108] It can be understood that the working light and the monitoring light both pass through the half-mirror 3 and the galvanometer 4, achieving coaxial propagation, so that the processing process of the workpiece 8 by the monitoring working light can be observed in real time through the monitoring light, and the coaxial imaging mode of the monitoring light and the working light is achieved. The coaxial design ensures accurate alignment between the laser processing path and the observation path, which can more clearly and accurately monitor and position the processing position during laser processing. At the same time, it is beneficial to simplify the components in the laser processing system 20 and save the occupied space. The laser coaxial imaging lens 10 can correct the aberration of the optical system and improve the imaging quality of the monitoring light, further improving the clarity and accuracy of the monitoring. Compared with the short focal length of the coaxial imaging lens in the related art, the laser coaxial imaging lens 10 has a longer focal length of up to 300 mm, achieving small size and long focal length, which is particularly important for laser processing systems 20 that require a larger working space, avoiding the risk of collision between the lens and the workpiece 8, and reducing the occupied space, which is beneficial to save space and facilitate operation and maintenance of the laser processing system 20. Moreover, the imaging quality is better, making the laser processing system 20 monitoring more accurate, which has significant advantages.

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

[0110] It can be understood that, by using only a green light source as the monitoring light source 2, the laser coaxial imaging lens 10 is designed for single-wavelength imaging, avoiding chromatic aberration and spectral interference that may occur in the laser coaxial imaging lens 10 when multiple wavelengths are used, ensuring the clarity and accuracy of the image. The single-wavelength design also simplifies the optical design of the laser processing system 20, reduces costs, and improves the stability of the laser processing system 20.

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

[0112] In some embodiments, the laser processing system 20 further includes a field lens 6 disposed between the galvanometer 4 and the workpiece 8. Through the arrangement of the field lens 6 and the laser coaxial imaging lens 10, a double-telecentric design is achieved, and the magnification of the monitoring light remains constant regardless of how the workpiece 8 moves within the focal depth range, and the size and shape of the final image do not change, which simplifies the image processing and measurement process and eliminates the need for complex geometric correction. The constant magnification and telecentric optical path design can provide a stable magnification for the image within a certain focal depth range, which is beneficial for operators to observe small details and make precise processing parameter adjustments.

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

[0114] In some embodiments, the laser processing system 20 further comprises a diaphragm 7, which is arranged between the galvanometer 4 and the half-transmission half-reflection mirror 3, and can be an entrance light port of the mechanical housing of the galvanometer 4. The distance D0 between the diaphragm 7 and the half-transmission half-reflection 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, the diaphragm 7 and the half-transmission half-reflection mirror 3 have a small interval, which is beneficial to the miniaturization design of the laser processing system 20. Moreover, the diaphragm 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 often occurring in the system with a separate light path, ensures uniform illumination and imaging in the entire field of view, is beneficial to obtaining a light spot with a better size, is beneficial to improving the processing effect of the working light on the workpiece 8, and at the same time, is beneficial to improving the quality of the light spot formed by the monitoring light on the camera 5, and is beneficial to improving the monitoring accuracy.

[0115] In some embodiments, the size x of the half-transmission half-reflection mirror 3 on the optical axis satisfies: 20≤x≤40mm, and the interval y between the image side of the half-transmission half-reflection mirror 3 and the object side of the first lens L1 on the optical axis satisfies: 5≤y≤20mm. Thus, the half-transmission half-reflection mirror 3 can have a better interval with the first lens L1 while realizing the transmission of the monitoring light and the reflection of 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 have a better imaging quality. Referring to Figure 3 , Figure 3 which is the spot diagram of the laser coaxial imaging lens 10 in an embodiment of the present application. It can be seen that most of the diffraction spots are concentrated within the Airy disk, which indicates that the imaging quality of the laser coaxial imaging lens 10 is better. Figure 4 which is the light fan diagram of the laser coaxial imaging lens 10 in an embodiment of the present application. The aberration correction of the laser coaxial imaging lens 10 is shown. It can be seen from the diagram that the spherical aberration, coma and astigmatism of the laser coaxial imaging lens 10 are effectively corrected. Figure 5 which is the transfer function curve of the laser coaxial imaging lens 10 in an embodiment of the present application. It can be seen from the diagram that the laser coaxial imaging lens 10 has a higher resolution and clarity, and has a better imaging quality. Figure 6 which is the field curvature and distortion curve of the laser coaxial imaging lens 10 in an embodiment of the present application. The field curvature and distortion of the laser coaxial imaging lens 10 are shown. It can be seen from the diagram that the ideal image plane and the actual image plane almost completely coincide, the laser coaxial imaging lens 10 has a better anti-distortion ability, and thus has a better imaging quality.

[0117] The application can realize coaxial imaging of the working light path and the monitoring light path by the design of the laser coaxial imaging lens 10, the half-transmission half-reflection mirror 3, the galvanometer 4, the field lens 6, the working light source 1 and the monitoring light source 2, is beneficial to real-time monitoring of the working state of the working light source 1 on the workpiece 8, and is beneficial to improving the monitoring accuracy. Moreover, the laser coaxial imaging lens 10 is beneficial to reducing aberration, spherical aberration and field curvature, and can correct chromatic aberration, has better imaging quality, thereby being beneficial to further improving the monitoring accuracy, and can clearly and accurately monitor and position the processing position in the laser processing process. Meanwhile, the laser coaxial imaging lens 10 adopts a cemented lens group, and the size of the multiple lenses and the spacing of the adjacent lenses are designed, which is beneficial to reducing the size of the laser coaxial imaging lens 10 and is beneficial to miniaturization design.

[0118] The technical features of the above-described embodiments can be combined arbitrarily, and to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0119] The above-described embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it should not be understood as the limitation of the patent application scope. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A laser coaxial imaging lens, characterized in that, The laser coaxial imaging lens comprises, in sequence from the object side to the image side along the optical axis: a first lens with positive refractive power, the object side surface of the first lens being convex, and the image side surface being convex; a first cemented lens group with positive refractive power, the first cemented lens group comprising a second lens and a third lens cemented with each other, the second lens having positive refractive power, the third lens having negative refractive power, the object side surface of the second lens being convex, and the image side surface being convex, the object side surface of the third lens being concave, and the image side surface being concave; a fourth lens with negative refractive power, the object side surface of the fourth lens being concave, and the image side surface being concave; a fifth lens with negative refractive power, the image side surface of the fifth lens being convex, and the object side surface being concave; a second cemented lens group with negative refractive power, the second cemented lens group comprising a sixth lens and a seventh lens cemented with each other, the sixth lens having negative refractive power, the seventh lens having positive refractive power, the object side surface of the sixth lens being concave, and the image side surface being concave, the object side surface of the seventh lens being convex, and the image side surface being convex; there are seven lenses in the laser coaxial imaging lens; the laser coaxial imaging lens satisfies the following conditional expression: | (R21-R32) / (R21+R32) | ≤ 0.4; and / or, the laser coaxial imaging lens satisfies the following conditional expression: | (R61-R72) / (R61+R72) | ≤ 0.

82. 2.The laser coaxial imaging lens according to claim 1, wherein, the laser coaxial imaging lens satisfies the following conditional expression: 15mm ≤ R11 ≤ 35mm; -470mm ≤ R12 ≤ -440mm; -25mm ≤ R41 ≤ -10mm; 10mm ≤ R42 ≤ 25mm; -125mm ≤ R51 ≤ -95mm; -25mm ≤ R52 ≤ -5mm; wherein 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, the image side surface of the first lens being 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 being 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, when the laser coaxial imaging lens satisfies the following conditional expression: | (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; and R32 is the curvature radius of the image side surface of the third lens; when the laser coaxial imaging lens satisfies the following conditional expression: | (R61-R72) / (R61+R72) | ≤ 0.82; -25mm ≤ R61 ≤ -5mm; 15mm ≤ R67 ≤ 35mm; -50mm ≤ R72 ≤ -35mm; Wherein, R61 is the radius of curvature of the object side of the sixth lens, R67 is the radius of curvature of the cemented surface of the sixth lens and the seventh lens; R72 is the radius of curvature of the image side 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 expression: 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 on the optical axis, D12 is the distance from the image side of the first lens to the object side 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 of the third lens to the object side 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 expression: 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, 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, which is arranged on the side of the seventh lens away from the sixth lens along the optical axis; Along the optical axis, the distance D78 between the image side of the seventh lens and the filter on the optical axis satisfies 5mm≤D78≤15mm, the size D8 of the filter on the optical axis satisfies: 1≤D8≤3mm; and the 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 expression: 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 Abbe number of the first lens, Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, Vd4 is the Abbe number of the fourth lens, Vd5 is the Abbe number of the fifth lens, Vd6 is the Abbe number of the sixth lens, Vd7 is the Abbe number of the seventh lens, and Vd8 is the Abbe number of the filter.

8. A laser processing system for processing a workpiece, characterized by, The laser processing system further comprises: a work light source configured to emit a work light; a monitoring light source configured to emit a monitoring light; a half-transmission half-reflection mirror and a galvanometer arranged in sequence along a propagation direction of the work light, the work light being reflected by the half-transmission half-reflection mirror to the galvanometer and then being reflected by the galvanometer to the workpiece; the monitoring light source is arranged 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 then is reflected by the galvanometer and transmitted through the half-transmission half-reflection mirror to the laser coaxial imaging lens; and a camera arranged on a side of the laser coaxial imaging lens away from the half-transmission half-reflection mirror, so as to receive the monitoring light transmitted through the laser coaxial imaging lens.

9. The laser processing system of claim 8, wherein, The laser processing system further comprises a field lens arranged between the galvanometer and the workpiece.

10. The laser processing system of claim 8, wherein, The laser processing system further comprises a diaphragm arranged between the galvanometer and the half-transmission half-reflection mirror, and a distance D0 between the diaphragm and the half-transmission half-reflection mirror on the optical axis satisfies 20mm≤D0≤50mm, and a radius a of a light spot formed by the monitoring light received by the camera satisfies 2.246μm≤a≤5.569μm.

Images