Laser focusing system and laser processing device

Abstract

The present application relates to a laser focusing system and a laser processing device. The laser focusing system comprises: a focusing lens group, comprising a first lens with negative optical power, a second lens with positive optical power, and a third lens with positive optical power, the object side and image side of the first lens are both concave, the image side of the second lens is convex, and the object side of the third lens is convex; a field lens, comprising a fourth lens with negative optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with positive optical power, the object side of the fourth lens is concave, the image side is convex, the object side of the fifth lens is concave, the object side of the sixth lens is concave, the image side is convex, and the image side of the seventh lens is convex. The above-mentioned laser focusing system is conducive to improving the quality of the light spot, while reducing the complexity and difficulty of calibration, and simplifying the debugging process of the laser focusing system.

Description

Technical Field

[0001] The present application relates to the field of laser processing technology, and in particular to a laser focusing system and a laser processing device. Background Art

[0002] The laser focusing system usually includes a focusing lens group, a galvanometer and a field lens. The light passes through the focusing lens group, the galvanometer and the field lens and is projected onto the workpiece to be processed. Among them, the focusing lens group can move along the optical axis to change the focal length of the laser focusing system, thereby adjusting the focusing depth of the laser on the workpiece to be processed, and the galvanometer can polarize the light path to adjust the focusing position of the laser on the workpiece to be processed, thereby realizing three-dimensional processing of the workpiece to be processed. The field lens is used to converge the laser onto the workpiece to be processed and improve the quality of the light spot. Laser focusing systems are widely used in the field of laser micro-nano manufacturing, especially in scenarios where three-dimensional curved surfaces or complex shapes need to be accurately etched. However, the calibration of traditional laser focusing systems is difficult, the process is complicated, and the quality of the light spot is difficult to guarantee. Summary of the invention

[0003] Based on this, it is necessary to provide a laser focusing system and a laser processing device to address the problems that the calibration of traditional laser focusing systems is difficult, the process is complicated, and the quality of the light spot is difficult to guarantee.

[0004] A laser focusing system, comprising in sequence along the laser propagation direction:

[0005] A focusing lens group, comprising, in sequence along the laser propagation direction, a first lens with negative optical power, a second lens with positive optical power, and a third lens with positive optical power, wherein the object side surface and the image side surface of the first lens are both concave surfaces, the image side surface of the second lens is a convex surface, and the object side surface of the third lens is a convex surface, and at least a part of the focusing lens group can be moved along the optical axis to achieve a focusing function;

[0006] And, the field lens includes, along the laser propagation direction, a fourth lens with negative optical focal power, a fifth lens with negative optical focal power, a sixth lens with positive optical focal power, a seventh lens with positive optical focal power and an eighth lens with positive optical focal power, the object side surface of the fourth lens is concave, and the image side surface is convex, the object side surface of the fifth lens is concave, the object side surface of the sixth lens is concave, and the image side surface is convex, and the image side surface of the seventh lens is convex.

[0007] In the above-mentioned laser focusing system, the focal length and surface design of each lens can form a good match, effectively reduce the telecentric angle of the laser focusing system, and improve the consistency of the roundness of the light spot at each position of the working surface, which is beneficial to improving the light spot quality of the laser focusing system and improving the processing quality of scanning processing using the laser focusing system. At the same time, the good match of each lens is also beneficial to reducing the moving stroke of the focusing part of the focusing lens group when the same working distance changes, thereby improving the optical lever of the laser focusing system, which is beneficial to reducing the occupied space and cost of the focusing setting of the laser focusing system. In addition, in the above-mentioned laser focusing system, the focusing lens group and the field lens are designed and simulated as an optical system, so that the focusing lens group and the field lens can form a good match, jointly realize the focusing function and improve the effect of light spot quality. Therefore, when the focusing lens group and the field lens are assembled on the laser processing device, the cooperation between the focusing lens group and the field lens is more closely coordinated, which is beneficial to reduce the complexity and difficulty of calibration and simplify the debugging process of the laser focusing system.

[0008] In one embodiment, the first lens is movable along the optical axis relative to the second lens to achieve a focusing function of the laser focusing system.

[0009] In one of the embodiments, the maximum movement distance of the first lens along the optical axis is 4 mm, and the working distance of the laser focusing system is 206.07 mm-246.07 mm.

[0010] In one embodiment, the object side surface of the second lens is convex, the image side surface of the fifth lens is convex, the object side surface of the seventh lens is concave, and the object side surface and image side surface of the eighth lens are both convex; and / or,

[0011] The laser focusing system also includes a galvanometer and a beam expander. The galvanometer is arranged between the focusing lens group and the field lens along the laser propagation direction, and the beam expander is arranged on the light incident side of the focusing lens group along the laser propagation direction.

[0012] In one embodiment, the laser focusing system satisfies the following condition:

[0013] 0.25≤|R11 / R12|≤0.37;

[0014] 1.4≤|R31 / R22|≤1.9;

[0015] 0.45≤|R41 / R42|≤0.6;

[0016] 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, R22 is the curvature radius of the image side surface of the second lens, R31 is the curvature radius of the object side surface of the third lens, R41 is the curvature radius of the object side surface of the fourth lens, and R42 is the curvature radius of the image side surface of the fourth lens.

[0017] In one embodiment, the laser focusing system satisfies the following condition:

[0018] -20mm≤R11≤-15mm; 54mm≤R12≤58mm; 202mm≤R21≤205mm;

[0019] -58mm≤R22≤-50mm; 85mm≤R31≤95mm; 45mm≤R41≤52mm;

[0020] -100mm≤R42≤-88mm; -158mm≤R51≤-151mm; -490mm≤R52≤-475mm;

[0021] -172mm≤R61≤-165mm; -124mm≤R62≤-108mm; -418mm≤R71≤-403mm;

[0022] -127mm≤R72≤-118mm; 890mm≤R81≤895mm; -527mm≤R82≤-518mm;

[0023] Among them, R21 is the curvature radius of the object side surface of the second lens, R51 is the curvature radius of the object side surface of the fifth lens, R52 is the curvature radius of the image side surface of the fifth lens, R61 is the curvature radius of the object side surface of the sixth lens, R62 is the curvature radius of the image side surface of the sixth lens, R71 is the curvature radius of the object side surface of the seventh lens, R72 is the curvature radius of the image side surface of the seventh lens, R81 is the curvature radius of the object side surface of the eighth lens, and R82 is the curvature radius of the image side surface of the eighth lens.

[0024] In one embodiment, the laser focusing system satisfies the following condition:

[0025] 1.2≤D45 / CT4≤1.9;

[0026] Wherein, D45 is the distance from the image side surface of the fourth lens to the object side surface of the fifth lens on the optical axis, and CT4 is the thickness of the fourth lens on the optical axis.

[0027] In one embodiment, the laser focusing system satisfies the following condition:

[0028] 1.3≤Nd1≤1.7; 1.1≤Nd2≤1.5; 1.5≤Nd3≤1.9; 1.4≤Nd4≤1.8;

[0029] 1.3≤Nd5≤1.7; 1.5≤Nd6≤1.9; 1.8≤Nd7≤2.2; 1.5≤Nd8≤1.9;

[0030] Among them, Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, Nd3 is the refractive index of the third lens, Nd4 is the refractive index of the fourth lens, Nd5 is the refractive index of the fifth lens, Nd6 is the refractive index of the sixth lens, Nd7 is the refractive index of the seventh lens, and Nd8 is the refractive index of the eighth lens.

[0031] In one embodiment, the laser focusing system satisfies the following condition:

[0032] 77≤Vd1≤83; 66≤Vd2≤72; 54≤Vd3≤60; 69≤Vd4≤74; 28≤Vd5≤34;

[0033] 24≤Vd6≤30; 13≤Vd7≤19; 29≤Vd8≤35;

[0034] Among them, 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 eighth lens.

[0035] A laser processing device comprises the laser processing device as described in any of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the structure of the laser processing device in some embodiments.

[0037] Figure 2 Schematic diagram of the optical path of the laser focusing system in some embodiments.

[0038] Figure 3 Schematic diagram of the optical path of the focusing lens assembly in three different focal length states in some embodiments.

[0039] Figure 4 Graphs showing telecentric angles of laser focusing systems at three different working distances in some embodiments.

[0040] Figure 5Graphs showing the circularity of the laser focusing system at three different working distances in some embodiments.

[0041] Figure 6 Graphs showing spot diameters of laser focusing systems at three different working distances in some embodiments.

[0042] Reference numerals:

[0043] 10. Laser processing device; 11. Laser; 20. Laser focusing system; 21. Beam expander; 22. Focusing lens group; L1. First lens; L2. Second lens; L3. Third lens; 23. Galvanometer; 24. Field lens; L4. Fourth lens; L5. Fifth lens; L6. Sixth lens; L7. Seventh lens; L8. Eighth lens; 25. Light-transmitting protection element. DETAILED DESCRIPTION

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] See also Figure 1 , Figure 1 The schematic diagram of the structure of the laser processing device 10 in some embodiments is shown. The laser processing device 10 provided in the present application includes but is not limited to being used in the field of laser micro-nano manufacturing, for example, in scenarios where three-dimensional curved surfaces or surfaces of objects with complex shapes need to be accurately etched. In some embodiments, the laser processing device 10 includes a laser 11 and a laser focusing system 20. The laser 11 is used to emit laser light. The type of the laser 11 and the laser wavelength band emitted by the laser 11 are not limited, and can be specifically designed according to the needs of the corresponding scene. The laser focusing system 20 includes a beam expander 21, a focusing lens group 22, a galvanometer 23, and a field lens 24 in sequence along the direction of laser propagation. The laser processing device 10 may also include a placement platform for placing the workpiece to be processed. The laser emitted by the laser 11 can be projected onto the workpiece to be processed on the placement platform after passing through the beam expander 21, the focusing lens group 22, the galvanometer 23, and the field lens 24 in sequence, and the workpiece to be processed is scanned and processed.

[0051] Among them, the beam expander 21 may include one or more lenses with optical focal length, which can collimate and / or expand the laser, and adjust the uniformity and aperture of the laser. At least part of the focusing lens group 22 can move along the optical axis to achieve the optical focusing function, that is, change the focal length and working distance of the laser focusing system 20, thereby changing the focusing position of the laser in the axial direction of the field lens 24 (hereinafter referred to as the Z-axis direction) to adapt to different processing positions of the surface of the workpiece to be processed in the Z-axis direction. The galvanometer 23 can adjust the emission angle of the laser after being reflected by the galvanometer 23 by rotating, thereby adjusting the focusing position of the laser in two mutually perpendicular directions (hereinafter referred to as the X-axis direction and the Y-axis direction) on the plane perpendicular to the axis of the field lens 24. The field lens 24 can adjust and converge the laser to the surface of the workpiece to be processed, improve the quality of the light spot, and thus improve the processing quality. It is understandable that the focusing lens group 22 adjusts the focusing position of the laser in the Z-axis direction, and the galvanometer 23 adjusts the focusing position of the laser in the X-axis direction and the Y-axis direction, so as to achieve a three-dimensional scanning effect on the workpiece being processed.

[0052] Furthermore, combined with Figure 2 and Figure 3 As shown, in some embodiments, the focusing lens group 22 includes a first lens L1 with negative optical power, a second lens L2 with positive optical power, and a third lens L3 with positive optical power in sequence along the laser propagation direction. The object side surface and the image side surface of the first lens L1 are both concave surfaces, the image side surface of the second lens L2 is convex, and the object side surface of the third lens L3 is convex. The field lens 24 includes a fourth lens L4 with negative optical power, a fifth lens L5 with negative optical power, a sixth lens L6 with positive optical power, a seventh lens L7 with positive optical power, and an eighth lens L8 with positive optical power in sequence along the laser propagation direction. The object side surface of the fourth lens L4 is concave and the image side surface is convex, the object side surface of the fifth lens L5 is concave, the object side surface of the sixth lens L6 is concave and the image side surface is convex, and the image side surface of the seventh lens L7 is convex.

[0053] In the above-mentioned laser focusing system 20, the focal length and surface design of each lens can form a good match, effectively reduce the telecentric angle of the laser focusing system 20, and improve the consistency of the roundness of the light spot at each position of the working surface, which is conducive to improving the light spot quality of the laser focusing system 20 and improving the processing quality of scanning processing using the laser focusing system 20. Specifically, the negative focal length and biconcave surface design of the first lens L1 can diverge the laser and adjust the propagation angle of the laser beam, so that the laser beam has a more suitable divergence state before entering the subsequent lens, which is conducive to the precise focusing of the subsequent lens. The focal length and surface design of the second lens L2 can initially focus the light, and with the focal length and surface design of the third lens L3, a high-precision focusing effect can be achieved, improving the accuracy and efficiency of laser processing. The negative focal length and concave-convex surface design of the fourth lens L4, in combination with the negative focal length and surface design of the fifth lens L5, can diverge the laser beam, improve the coverage of the laser beam, and meet the requirements of different processing area sizes. The coordination of the optical power and surface design of the sixth lens L6, the seventh lens L7 and the eighth lens L8 is conducive to converging the laser beam so as to project the laser beam onto the workpiece to form a light spot. It is also conducive to optimizing the light spot and improving the quality of the light plate so that parameters such as the light spot shape, energy density and uniformity can meet the laser processing requirements.

[0054] At the same time, the good coordination of the lenses is also beneficial to reducing the moving stroke of the focusing part of the focusing lens group 22 when the same working distance changes, thereby improving the optical lever of the laser focusing system 20, which is beneficial to reducing the occupied space and cost of the focusing setting of the laser focusing system 20, such as reducing the space occupied by the focusing moving stroke of the first lens L1, and the weight and volume of the driving element used to drive the first lens L1 to move.

[0055] In addition, in the above-mentioned laser focusing system 20, the focusing lens group 22 and the field lens 24 are designed and simulated as an optical system, so that the focusing lens group 22 and the field lens 24 can form a good cooperation, and jointly realize the focusing function and improve the effect of the quality of the light spot. Therefore, compared with the traditional laser focusing system in which the focusing lens group and the field lens are designed separately, and the focusing function of the focusing lens group and the adjustment function of the field lens on the light spot are relatively independent, when the focusing lens group 22 and the field lens 24 are assembled on the laser processing device 10, the cooperation between the focusing lens group 22 and the field lens 24 is more closely coordinated, which is conducive to reducing the complexity and difficulty of calibration and simplifying the debugging process of the laser focusing system 20.

[0056] In some embodiments, the first lens L1 can move along the optical axis relative to the second lens L2 to achieve the focusing function of the laser focusing system 20, and the mobile focusing of the first lens L1 can be achieved by any suitable driving mechanism such as a voice coil motor. The focusing function of the laser focusing system 20 is achieved by driving the first lens L1 located at the front end of the focusing lens group 22 and having a negative optical focal length to move, and the adjustment effect of the optical focal length and surface design of each lens of the laser focusing system 20 on the laser beam can be combined. The laser focusing system 20 can have a good light spot under different working distances, which is beneficial to improving the quality of laser processing, and is also beneficial to increasing the optical lever of the laser focusing system 20, which is beneficial to reducing the space occupied and cost of the laser focusing system 20, and increasing the scanning range of the laser beam to meet the scanning requirements of workpieces of different sizes.

[0057] For example, in some embodiments, the maximum movement stroke of the first lens L1 along the optical axis is 4 mm, and the working distance of the laser focusing system 20 is 206.07 mm-246.07 mm, then the optical lever of the laser focusing system 20 is 1:10, which can effectively compress the movement stroke of the first lens L1 under the same working distance change. Figure 3 , from top to bottom, respectively, schematic diagrams of optical paths of the focusing lens group 22 in three different focal length states are shown, wherein, in the second state relative to the first state, the first lens L1 moves 2 mm along the optical axis in a direction away from the second lens L2, and the working distance is reduced by 20 mm, and in the third state relative to the first state, the first lens L1 moves 2 mm along the optical axis in a direction close to the second lens L2, and the working distance is increased by 20 mm. It can be seen that when the moving stroke of the first lens L1 relative to the second lens L2 is ±2 mm, a variation range of ±20 mm in the working distance can be achieved, effectively improving the optical leverage of the laser focusing system 20.

[0058] In some embodiments, the object side surface of the second lens L2 is convex, the image side surface of the fifth lens L5 is convex, the object side surface of the seventh lens L7 is concave, and the object side surface and image side surface of the eighth lens L8 are both convex. In combination with other optical power and surface design of each lens, it is beneficial to improve the quality of the light spot, so that the laser focusing system 20 has good processing quality under different working distances.

[0059] In some embodiments, the laser focusing system 20 satisfies the conditional formula: 0.25≤|R11 / R12|≤0.37; wherein R11 is the radius of curvature of the object side surface of the first lens L1, and R12 is the radius of curvature of the image side surface of the first lens L1. For example, |R11 / R12| can be 0.25, 0.27, 0.29, 0.33, 0.35, and 0.37. When the above conditional formula is met, the ratio of the radius of curvature of the object side surface and the image side surface of the first lens L1 can be reasonably configured, thereby reasonably controlling the divergence degree of the light passing through the first lens L1, which is conducive to balancing various aberrations and improving the quality of the focused light spot.

[0060] In some embodiments, the laser focusing system 20 satisfies the conditional formula: 1.4≤|R31 / R22|≤1.9; wherein R22 is the radius of curvature of the image side surface of the second lens L2, and R31 is the radius of curvature of the object side surface of the third lens L3. For example, |R31 / R22| can be: 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9. When the above conditional formula is met, the ratio of the radius of curvature of the object side surface of the third lens L3 to the image side surface of the second lens L2 can be reasonably configured, thereby reasonably controlling the transition of light between the second lens L2 and the third lens L3, which is beneficial to improving the light spot quality and focusing accuracy.

[0061] In some embodiments, the laser focusing system 20 satisfies the conditional formula: 0.45≤|R41 / R42|≤0.6; wherein R41 is the radius of curvature of the object side surface of the fourth lens L4, and R42 is the radius of curvature of the image side surface of the fourth lens L4. For example, |R41 / R42| can be: 0.45, 0.5, 0.54, 0.59 or 0.6. When the above conditional formula is met, the ratio of the radius of curvature of the object side surface and the image side surface of the fourth lens L4 can be reasonably configured, which is conducive to reasonably controlling the divergence of light in the fourth lens L4, balancing the aberrations of field curvature and astigmatism, thereby improving the uniformity of the light spot and improving the consistency and reliability of laser processing.

[0062] In some embodiments, the laser focusing system 20 satisfies the conditional formula: 1.2≤D45 / CT4≤1.9; 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 CT4 is the thickness of the fourth lens L4 on the optical axis. For example, D45 / CT4 can be: 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9. When the above conditional formula is met, the divergence angle of the laser beam in the fourth lens L4 and the spatial distance of divergence between the fourth lens L4 and the fifth lens L5 can be reasonably configured, which is conducive to reasonably controlling the divergence degree of the light, correcting aberrations such as field curvature, improving the uniformity of the light spot, and thus helping to improve the quality of laser processing.

[0063] In some embodiments, the laser focusing system 20 further includes an aperture, which is disposed on the light-entering side of the first lens L1. The aperture is provided to limit the cross-sectional size of the laser beam entering the laser focusing system 20, and to control the energy and power density of the beam to meet different processing requirements. In some embodiments, the laser focusing system 20 further includes a light-transmitting protective element 25 disposed on the light-exiting side of the eighth lens L8. The light-transmitting protective element 25 includes but is not limited to a glass plate, etc. The light-transmitting protective element 25 can provide protection for the field lens 24, so that the field lens 24 is protected from dust, scratches and other environmental factors.

[0064] In some embodiments, the object side and image side of each lens are both spherical, that is, the radius of curvature of the object side and image side of each lens is equal. Of course, in other embodiments, the object side and image side of each lens may also be aspherical, or a combination of spherical and aspherical surfaces. The material of each lens includes but is not limited to any suitable material such as glass or plastic.

[0065] In some embodiments, various parameters of the laser focusing system 20 are given in the following Table 1, wherein the first row of each lens corresponds to the light incident surface of the lens, and the second row corresponds to the light exit surface of the lens.

[0066] Table 1

[0067]

[0068] As shown in Table 1, in some embodiments, the laser focusing system 20 satisfies the following conditions: -20mm≤R11≤-15mm; 54mm≤R12≤58mm; 202mm≤R21≤205mm; -58mm≤R22≤-50mm; 85mm≤R31≤95mm; 45mm≤R41≤52mm; -100mm≤R42≤-88mm; -158mm≤R51≤-151mm; -490mm≤R52≤-475mm; -172mm≤R61≤-165mm; -124mm≤R62≤-108mm; -418mm≤R71≤-403mm; -127 mm≤R72≤-118mm;890mm≤R81≤895mm;-527mm≤R82≤-518mm;wherein, R21 is the radius of curvature of the object side surface of the second lens L2, R51 is the radius of curvature of the object side surface of the fifth lens L5, R52 is the radius of curvature of the image side surface of the fifth lens L5, R61 is the radius of curvature of the object side surface of the sixth lens L6, R62 is the radius of curvature of the image side surface of the sixth lens L6, R71 is the radius of curvature of the object side surface of the seventh lens L7, R72 is the radius of curvature of the image side surface of the seventh lens L7, R81 is the radius of curvature of the object side surface of the eighth lens L8, and R82 is the radius of curvature of the image side surface of the eighth lens L8. When the above conditional formula is met, the radius of curvature of the object side surface and the image side surface of each lens can be reasonably designed, so that each lens cooperates well, and the spot quality can be effectively improved, thereby improving the laser processing quality.

[0069] As shown in Table 1, in some embodiments, the laser focusing system 20 satisfies the conditional formula: 1.3≤Nd1≤1.7; 1.1≤Nd2≤1.5; 1.5≤Nd3≤1.9; 1.4≤Nd4≤1.8; 1.3≤Nd5≤1.7; 1.5≤Nd6≤1.9; 1.8≤Nd7≤2.2; 1.5≤Nd8≤1.9; 77≤Vd1≤83; 66≤Vd2≤72; 54≤Vd3≤60; 69≤Vd4≤74; 28≤Vd5≤34; 24≤Vd6≤30; 13≤Vd7≤19; 29≤Vd8≤35; wherein Nd1 is the refractive index of the first lens L1, N d2 is the refractive index of the second lens L2, Nd3 is the refractive index of the third lens L3, Nd4 is the refractive index of the fourth lens L4, Nd5 is the refractive index of the fifth lens L5, Nd6 is the refractive index of the sixth lens L6, Nd7 is the refractive index of the seventh lens L7, Nd8 is the refractive index of the eighth lens L8, Vd1 is the Abbe number 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 eighth lens L8. When the above conditional expressions are met, the refractive index and Abbe number of each lens can be reasonably configured, which is beneficial to correct various aberrations such as chromatic aberration, spherical aberration, coma, etc., and improve the quality of the light spot. It is also beneficial to adapt to the corresponding laser wavelength. For example, when the laser processing device 10 uses the near-infrared band for laser processing, through the reasonable configuration of each lens, the laser focusing system 20 can provide good light spot quality for the near-infrared band, such as providing good light spot quality for near-infrared light with a wavelength of 1064nm, thereby improving the quality of laser processing.

[0070] In some embodiments, the focal length of the field lens 24 is 167 mm, which can effectively converge the laser from the focusing lens group 22 and the galvanometer 23 onto the workpiece to be processed to meet the scanning requirements. In some embodiments, the entrance pupil diameter of the laser focusing system 20 is 5 mm, the maximum working range is 80 mm (X-axis direction) * 80 mm (Y-axis direction) * 40 mm (Z-axis direction), and the maximum focusing stroke of the first lens L1 along the optical axis is 4 mm. By effectively increasing the optical lever of the laser focusing system 20, a larger range of working distances can be achieved through a smaller focusing stroke of the first lens L1, meeting the scanning requirements of different depths, and improving the zoom capability and flexibility of the laser focusing system 20. The focusing spot diameter of the laser focusing system 20 is less than 35 um, which can meet the diameter and energy required for laser scanning.

[0071] Combination Figure 4 , Figure 5 and Figure 6 As shown, Figure 4From left to right, the telecentric angle diagrams of the laser focusing system 20 when the working distances are 226.07 mm, 206.07 mm, and 246.07 mm are shown respectively. Figure 4 It can be seen that the maximum telecentric angle in the entire scanning field is 1°, which can improve the consistency of the processing effects at the edge and in the middle, thereby helping to improve the laser processing accuracy and quality. Figure 5 From left to right, the circularity diagrams of the laser focusing system 20 when the working distances are 226.07 mm, 206.07 mm, and 246.07 mm are shown respectively. Figure 5 It can be seen that when the working distance is 226.07mm, the roundness of the focused spot is between 0.985 and 1.015; when the working distance is 206.07mm and 246.07mm, the roundness of the focused spot is between 0.95 and 1.05, and the change in the roundness of the focused spot in the three-dimensional scanning field is within 5%, with good spot quality. Figure 6 From left to right, they are the spot diameter diagrams of the laser focusing system 20 when the working distances are 226.07 mm, 206.07 mm, and 246.07 mm. Figure 6 It can be seen that the focus spot diameter meets the data in Table 2 below, the focus spot diameter variation is less than 1.4um, and the processing consistency is good.

[0072] Table 2

[0073] Working distance / mm 226.07 206.07 246.07 Minimum spot diameter of the inscribed circle in the scanning field / μm 32.38 33.36 32.31 Maximum spot diameter of the inscribed circle in the scanning field / μm 33.08 34.68 33.56 Maximum change of spot diameter / μm 0.70 1.32 1.25

[0074] 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.

[0075] 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 focusing system, characterized in that: Along the direction of laser propagation, it includes: A focusing lens group, comprising, in sequence along the laser propagation direction, a first lens with negative optical power, a second lens with positive optical power, and a third lens with positive optical power, wherein the object side surface and the image side surface of the first lens are both concave surfaces, the image side surface of the second lens is a convex surface, and the object side surface of the third lens is a convex surface, and at least a part of the focusing lens group can be moved along the optical axis to achieve a focusing function; And, the field lens includes, along the laser propagation direction, a fourth lens with negative optical focal power, a fifth lens with negative optical focal power, a sixth lens with positive optical focal power, a seventh lens with positive optical focal power and an eighth lens with positive optical focal power, the object side surface of the fourth lens is concave, and the image side surface is convex, the object side surface of the fifth lens is concave, the object side surface of the sixth lens is concave, and the image side surface is convex, and the image side surface of the seventh lens is convex.

2. The laser focusing system according to claim 1, characterized in that: The first lens can move along the optical axis relative to the second lens to achieve a focusing function of the laser focusing system.

3. The laser focusing system according to claim 2, characterized in that: The maximum movement distance of the first lens along the optical axis is 4 mm, and the working distance of the laser focusing system is 206.07 mm-246.07 mm.

4. The laser focusing system according to claim 1, characterized in that: The object side surface of the second lens is convex, the image side surface of the fifth lens is convex, the object side surface of the seventh lens is concave, and both the object side surface and the image side surface of the eighth lens are convex; and / or, The laser focusing system further comprises a galvanometer and a beam expander. The galvanometer is arranged between the focusing lens group and the field lens along the laser propagation direction, and the beam expander is arranged on the light incident side of the focusing lens group along the laser propagation direction.

5. The laser focusing system according to claim 1, characterized in that: The laser focusing system satisfies the following conditional formula: 0.25≤|R11 / R12|≤0.37; 1.4≤|R31 / R22|≤1.9; 0.45≤|R41 / R42|≤0.6; 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, R22 is the curvature radius of the image side surface of the second lens, R31 is the curvature radius of the object side surface of the third lens, R41 is the curvature radius of the object side surface of the fourth lens, and R42 is the curvature radius of the image side surface of the fourth lens.

6. The laser focusing system according to claim 5, characterized in that: The laser focusing system satisfies the following conditional formula: -20mm≤R11≤-15mm; 54mm≤R12≤58mm; 202mm≤R21≤205mm; -58mm≤R22≤-50mm; 85mm≤R31≤95mm; 45mm≤R41≤52mm; -100mm≤R42≤-88mm; -158mm≤R51≤-151mm; -490mm≤R52≤-475mm; -172mm≤R61≤-165mm; -124mm≤R62≤-108mm; -418mm≤R71≤-403mm; -127mm≤R72≤-118mm; 890mm≤R81≤895mm; -527mm≤R82≤-518mm; Among them, R21 is the curvature radius of the object side surface of the second lens, R51 is the curvature radius of the object side surface of the fifth lens, R52 is the curvature radius of the image side surface of the fifth lens, R61 is the curvature radius of the object side surface of the sixth lens, R62 is the curvature radius of the image side surface of the sixth lens, R71 is the curvature radius of the object side surface of the seventh lens, R72 is the curvature radius of the image side surface of the seventh lens, R81 is the curvature radius of the object side surface of the eighth lens, and R82 is the curvature radius of the image side surface of the eighth lens.

7. The laser focusing system according to claim 1, characterized in that: The laser focusing system satisfies the following conditional formula: 1.2≤D45 / CT4≤1.9; Wherein, D45 is the distance from the image side surface of the fourth lens to the object side surface of the fifth lens on the optical axis, and CT4 is the thickness of the fourth lens on the optical axis.

8. The laser focusing system according to claim 1, characterized in that: The laser focusing system satisfies the following conditional formula: 1.3≤Nd1≤1.7; 1.1≤Nd2≤1.5; 1.5≤Nd3≤1.9; 1.4≤Nd4≤1.8; 1.3≤Nd5≤1.7; 1.5≤Nd6≤1.9; 1.8≤Nd7≤2.2; 1.5≤Nd8≤1.9; Among them, Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, Nd3 is the refractive index of the third lens, Nd4 is the refractive index of the fourth lens, Nd5 is the refractive index of the fifth lens, Nd6 is the refractive index of the sixth lens, Nd7 is the refractive index of the seventh lens, and Nd8 is the refractive index of the eighth lens.

9. The laser focusing system according to claim 1, characterized in that: The laser focusing system satisfies the following conditional formula: 77≤Vd1≤83; 66≤Vd2≤72; 54≤Vd3≤60; 69≤Vd4≤74; 28≤Vd5≤34; 24≤Vd6≤30; 13≤Vd7≤19; 29≤Vd8≤35; Among them, 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 eighth lens.

10. A laser processing device, characterized in that: It comprises the laser processing device as described in any one of claims 1 to 9.

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